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Oil & gas industry of Ukraine geology
www.naftogaz.com/naftogaz_galuz
5/2013
Prediction of non‐structural hydrocarbon traps in Upper Visean stratum on the slopes of near‐axial troughs of DDD Yevdoshchuk M.I., Bartashchuk L.O.
Concerning the problem of development of methane hydrate potential of the Black Sea Kychka O.A., Koval A.M., Tyshchenko A.P., Dovzhok T.Y., Korovnachenko Y.Y.
On some problematic issues of the current efficiency of oil exploration work Zyuzkevych M.P.
17th International Forum of Oil and Gas Industry Oil and Gas 2013
On 22 – 24 October 2013 Kyiv hosted the 17th International Forum of Oil and Gas Industry, Oil & Gas 2013,
which organized an international exhibition.
The opening of the forum was attended by the Deputy Minister of Energy and Coal Industry of Ukraine Andriy Bondarenko, deputy chairman of the National Joint Stock Company Naftogaz of Ukraine Vadym Chuprun, representatives of the Cabinet of Ministers of Ukraine, the Verkhovna Rada of Ukraine, diplomats, heads of industrial establishments and companies.
During the Forum opening, the Deputy Minister of Energy and Coal Industry of Ukraine Andriy Bondarenko said that our country is now at the center of the European energy routes, which determines its particular importance in provision of the European market with natural gas and oil, and the Ukrainian oil and gas forum is one of the most important actions in Eastern Europe, which aims at familiarizing the community with the situation in the oil and gas industry, its further development strategy, highlighting the role of Ukraine in the international fuel and energy market, presenting the achievements of companies and enterprises of the oil and gas industry as well as creating the new and developing the existing mutually beneficial relationships with foreign partners.
An integral part of the Oil and Gas forum was an international scientific conference Oil and Gas Complex of
Ukraine - Development Strategy."
Oil and Gas Forum is a great opportunity for effective business communication at the highest level, the results of which will become the basis for development of a long-term program of international cooperation and conclusion of strategic contracts.
This year it was attended by more than 130 companies from 16 countries, including Denmark, Russia, Austria, Canada, Italy, China, Switzerland, Germany and others.
The participants demonstrated the advanced equipment and technology for the exploration, production, transportation, processing and storage of oil and gas as well as systems for automation and monitoring of processes, security tools and services for the industry and so on.
General Meeting of the Ukrainian Oil and Gas Academy and the 9th International Scientific Practical Conference
Oil and Gas of Ukraine 2013
From 4 to 6 September 2013 Yaremche hosted the ordinary General Meeting of the Ukrainian Oil and Gas Academy (UOGA) and the 9th International Scientific and Practical Conference Oil and Gas of Ukraine – 2013 confined thereto. They were dedicated to the 20th anniversary of the UOGA and discussion of achievements and challenges of oil and gas prospects and evaluation of oil and gas industry of Ukraine in the future.
At the meeting 20 UOGA members were awarded a commemorative jubilee gold medal in honor of the 20th anniversary of the Academy, another 17
people were awarded diplomas or gratitude and gifts, i.e. books edited by the Candidate of Technical Sciences, UOGA Academician, Z.P. Osinchuk, Oil and Gas Industry of Ukraine: Progress and Personalities.
The conference discussed the current problems of the oil and gas complex of Ukraine, examined the performance of the research organizations and enterprises of oil and gas complex of Ukraine, an exchange of information on the use of new technologies and diversification of hydrocarbons in Ukraine, as well as the prospects of oil and gas industry in Ukraine for the future development of hydrocarbon resources of little-permeable reservoirs, shale gas and gas hydrates.
33 reports were presented, and the particular interest was evoked by report of the Professor of the University of Texas, Y.F. Makogon on the Black Sea Gas Hydrates on the history of opening and current state of the gas hydrates research in the world, as well as the prospects for the development of gas hydrates in the Black Sea.
The results of the UOGA general meeting and conference became the basis of a joint decision, which envisages the preparation of the text of appeal to the public and the authorities with scientifically sound information about the need to develop the non-conventional types of hydrocarbon resources, including shale gas, tight rock gas, coal rock methane, and gas hydrates to develop the evidence-based proposals for prudent use of hydrocarbon resources, efficient and environmentally sound operation of oil and gas as well as energy saving technologies in Ukraine, to publish them in the media and send to the executive agencies and leading companies within the industry. In order to maintain the capacity and productive work of the institution of higher education, it was proposed to support the initiative of the team of Drogobych College of Oil and Gas on its affiliation to Ivano-Frankivsk National Technical University of Oil and Gas as a legal entity. It also was decided to ask the leading oil and gas companies and private institutions eligible for subsoil use under special permits to provide the geological and geological-industrial information required to produce a second enlarged issue of the Atlas of Oil and Gas Fields and prepare the oil and gas encyclopedia.
Chief academic secretary of UNGA,
Candidate of Geological Sciences, А.М. Koval
In Memoriam of М.P. Kovalko
Our destiny is special. On the verge of millennia. We struggled and loved. Every day and every moment
On November 19, 2013 a memorial plate Mykhaylo Petrovych Kovalko (1944–2012) a renowned specialist of the industry, Doctor of Technical Sciences, people’s deputy of Ukraine of two convocations, the Honored Industrial Employee of Ukraine, the Laureat of the State Award of Ukraine for Science and Technology, was solemnly placed on the front wall of Drogobych College of Oil and Gas. He graduated from this establishment in 1962.
Mr. Kovalko was born in a large rural family in the village of Livchytsi, Gorodok district, Lviv oblast. He graduated from the 7 years’ school magna cum laude and continued his studies in the Oil and Gas Institute of the Academy of National Economy at the USSR Council of Ministers.
Mr. Kovalko started his labor as a gas production operator, later on he worked as a deputy director of Shebelynka Gas Mining Administration, chief engineer, the director of Poltava gas industrial administration, chief engineer of Ukrgasprom association, chairman of the State Committee of Ukraine for Oil and Gas, chairman of the State Committee of Ukraine for energy preservation, headed the Committee of Verkhovna Rada of Ukraine for fuel and energy, nuclear policy and nuclear safety.
М.P. Kovalko is an organizer and an active participant of implementation of numerous innovating technologies in oil and gas industry, in particular the cycling process technologies, effective means of struggling with carbon dioxide attack, new drilling equipment, the author of more than 90 publications and 35 inventions, as well as 10 collections of poems and many music plates. He is the initiator of the structures redesign of the oil and gas complex, elaboration of the state programs for development of oil and gas industry of Ukraine and energy saving, Ukraine’s accession to the International Gas Union and Global Oil Congress.
М. Kovalko Tehe event of commemoration of the memory of Mykhaylo Kovalko gathered the delegations of the technical school graduates from Kyiv, Boryslav, Dolyna, Nadvirna, Drogobych and other regions of Ukraine, the specialists who personally knew and worked with Mykhaylo. The speakers stressed an outstanding talent of Mr. Kovalko as an industrialist, scientist, organizer of the oil and gas complex of Ukraine, underlining his significant contribution to the industry development and improvement of our state authority in the world.
The labor path and achievements of Mykhaylo Kovalko (will serve a good example for the young generation, the college graduates who are to create the future of our industry and state.
Publication name
Oil and Gas Industry of Ukraine
Scientific and production magazine. Published once in 2 months
Co-founders
National Joint-Stock Company Naftogaz of Ukraine
Ivano-Frankivsk National Technical University of Oil and Gas
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E. M. Bakulin
5/2013
(5) September – October
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Recommended for publishing by the Scientific and Technical Board of National joint-stock company Naftogaz of Ukraine
CONTENTS OIL AND GAS GEOLOGY
YEVDOSHCHUK M.I., BARTASHCHUK L.O.
Prediction of non-structural hydrocarbon traps in Upper Visean stratum on the slopes of near-axial troughs of DDD…………………………………………………………………………………………………………………………………………….. 3
VLADYKA V.M., PUSH A.O., NESTERENKO M.Yu., BALATSKYI R.S.
Trends of changing reservoir properties of Sarmatian stage rocks of the northwestern part of Bilche-Volytske area under different facial conditions of sedimentation........................................................ ……………………………………………………........................................11
KOVAL Ya.M.
Improvement of geophysical well logging data interpretation by constructing rock distribution patterns according to the cement type..................................................................... ………………………………………………………............................................................15
ZIUZKEVYCH M.P.
On some problematic issues of the current efficiency of oil exploration work......................................... ..........................................................20
IVANYSHYN V.A., KOPCHALIUK A.Y.
Paleotectonics of Yaroshivska area..................................................................................................... ...............................................................22
MACHUZHAK M.I., LYZANETS A.V., TYKHOMYROV A.S.
New areas of focus for finding large deposits of hydrocarbons in DDD...................................... .....................................................................31
kYCHKA O.A., KOVAL A.M., TYSHCHENKO A.P., DOVZHOK T.Ye., KOROVNYCHENKO Ye.Ye.
Concerning the problem of development of methane hydrate potential of the Black Sea........................ ………...........................................37
OIL AND GAS PRODUCTION
VOITENKO Yu.I.
The effectiveness of strong methods of stimulation of oil and gas production and the prospects of their use for unconventional reservoirs............................................................................................................... ........................................... ................................................43
OIL AND GAS TRANSPORTATION AND STORAGE
PIANYLO Ya.D., VAVRYCHUK P.H.
Diffusion of gases in porous media taking into account the convective component........................................................ ...................................46
INDUSTRY EXPERTS
Marukhniak M. Y.................................................................................................................................................................................................10
Kozak F. V. ............................................................................................ ............................................................................................................14
Information................................................................................. ..... .................................................................................................9,16,41,45,49
Oil & Gas Industry of Ukraine Editor-in-chief
Ievhen Mykolayovych Bakulin - Chairman of the National Joint Stock Company "Naftogaz of Ukraine"
Deputy chief editors
Vadim Prokopovych Chuprun - Deputy Chairman of the National Joint Stock Company "Naftogaz of Ukraine"
Ievstakhiy Ivanovych Kryzhanivskyy - Doctor of Engineering Sciences, professor, corresponding member of The National Academy of Sciences of Ukraine, the Rector of Ivano-Frankivsk National Technical University of Oil and Gas
Editorial board
Oleg Maksimovych Adamenko - Doctor of Geologo-Mineralogical Sciences
Yurii Volodymyrovych Banakhevych - Doctor of Engineering Sciences
Serhii Valeriyovych Bojchenko - Doctor of Engineering Sciences
Mykhailo Mykhailovych Bratychak - Doctor of Chemical Sciences
Frants Frantsovych Butynets - Doctor of Economic Sciences
Hennadiy Borysovych Varlamov - Doctor of Engineering Sciences
Volodymyr Mykhailovych Vasyliuk - Candidate of Engineering Sciences
Yurii Oleksandrovych Venhertsev - Doctor of Philosophical Sciences, Candidate of Engineering Sciences
Serhiy Andriiovych Vyzhva - Doctor of Geological Sciences
Yaroslav Stepanovych Vytvytskyi - Doctor of Economic Sciences
Mykhailo Davydovych Hinzburh - Doctor of Engineering Sciences
Vasyl Vasylovych Hladun - Doctor of Geological Sciences
Petro Fedosiiovych Hozhyk - Doctor of Geological Sciences, member of The National Academy of Sciences of Ukraine
Liliana Tarasivna Horal - Doctor of Economic Sciences
Oleksandr Ivanovych Hrytsenko - Doctor of Engineering Sciences, corresponding member of Russian Academy of Sciences
Volodymyr Yaroslavovych Hrudz - Doctor of Engineering Sciences, professor
Mykola Oleksiiovych Danyliuk - Doctor of Economic Sciences
Tetiana Yevhenivna Dovzhok - Candidate of Geological Sciences
Volodymyr Mykhailovych Doroshenko - Doctor of Engineering Sciences
Oksana Teodorivna Drahanchuk - Doctor of Engineering Sciences
Dmytro Oleksandrovych Yeher - Doctor of Engineering Sciences, corresponding member of The National Academy of Sciences of Ukraine
Yurii Oleksandrovych Zarubin - Doctor of Engineering Sciences
Oleksandr Yuriiovych Zeikan - Candidate of Geological Sciences
Ihor Mykolaiovych Karp - Doctor of Engineering Sciences, member of The National Academy of Sciences of Ukraine
Oleh Mykhailovych Karpash - Doctor of Engineering Sciences
Oleksii Mykolaiovych Karpenko - Doctor of Geological Sciences
Ihor Stepanovych Kisil - Doctor of Engineering Sciences
Volodymyr Pavlovych Kobolev - Doctor of Geological Sciences
Yurii Petrovych Kolbushkin - Doctor of Economic Sciences
Roman Mykhailovych Kondrat - Doctor of Engineering Sciences
Mykhailo Dmytrovych Krasnozhon - Doctor of Geological Sciences
Ihor Mykolaiovych Kurovets - Candidate of Geologo-Mineralogical Sciences
Mykola Volodymyrovych Lihotskyi - Candidate of Engineering Sciences
Oleksandr Yukhymovych Lukin - Doctor of Geologo-Mineralogical Sciences, member of The National Academy of Sciences of Ukraine
Borys Yosypovych Maievskyi - Doctor of Geologo-Mineralogical Sciences
Yurii Fedorovych Makohon - Doctor of Engineering Sciences (University of Texas, USA)
Mykhailo Ivanovych Machuzhak - Candidate of Geologo-Mineralogical Sciences
Oleksandr Oleksandrovych Orlov - Doctor of Geologo-Mineralogical Sciences
Zynovii Petrovych Osinchuk - Candidate of Engineering Sciences
Myroslav Ivanovych Pavliuk - Doctor of Geologo-Mineralogical Sciences, corresponding member of The National Academy of Sciences of Ukraine
Viktor Pavlovych Petrenko - Doctor of Economic Sciences
Oleksandr Pavlovych Petrovskyi - Doctor of Geological Sciences
Viktor Mykhailovych Svitlytskyi - Doctor of Engineering Sciences
Mariia Dmytrivna Serediuk - Doctor of Engineering Sciences
Orest Yevhenovych Serediuk - Doctor of Engineering Sciences
Vitalii Ivanovych Starostenko - Doctor of Physico-mathematical Sciences,member of The National Academy of Sciences of Ukraine
Serhii Oleksandrovych Storchak - Doctor of Engineering Sciences
Leonid Mykhailovych Unihovskyi - Doctor of Engineering Sciences
Dmytro Dmytrovych Fedoryshyn - Doctor of Geological Sciences
Illia Mykhailovych Fyk - Doctor of Engineering Sciences
Pavlo Mykolaiovych Khomyk
Ihor Ivanovych Chudyk - Doctor of Engineering Sciences
Anatolii Petrovych Chukhlib - Candidate of Economic Sciences
Eduard Anatoliiovych Shvydkyi - Candidate of Economic Sciences
Oleh Anatoliiovych Shvydkyi - Director of "Naukanaftogaz"
Anatolii Stepanovych Shevchuk - Candidate of Engineering Sciences
Contributors to this issue
Management of Science and Technology Policy
National Joint Stock Company "Naftogaz of Ukraine" Department of the publication organization of scientific and practical journal
Head of Department
T.P. Umuschenko
Editor N.H. Vorona
Delivered on 01.10.2013. Published: 05/11/2013 Format 205 × 285. Paper coated. Offset printing.
OIL AND GAS GEOLOGY
Forecast of hydrocarbons non-folded traps in Upper Visean deposits of Dnipro-Donets depression
UDK 550.8/553.98(477)
© M.I. Yevdoschuk
Doctor of Geological Science
L.O. Bartaschuk
Institute of Geological Sciences of National Academy of Science of Ukraine
Favorable geological preconditions for accumulation of accumulative sand bodies–reservoirs were studied and conditions of formation of related to them lithological, stratigraphic and combined oil and gas traps on the slopes of large near-axial troughs. Features of the geological structure of Upper Visean deposits on the northern slope of Ordaniv trough were investigated. A complex methodology of detecting non-anticlinal hydrocarbon traps, which includes paleotectonic, paleogeographic methods, detailed correlation of natural reservoirs by logging data and 3D seismic prospecting, as well as attributive analysis of the wavefield . The case of peripheral part of the West Solohivske gas-condensate field (GCF) shows the effectiveness of the new complex methodology. The hydrocarbon potential of Upper Visean terrigenous deposits was assessed for the area of Ordaniv trough northern slope in the area of West Solohivske structure.
Key words: forecast, reservoir, hydrocarbons, non-anticlinal traps, depression, Dnipro-Donets depression, Visean deposits
Despite the fact that all the known anticlinal structures have been already known, it is possible to find at their periphery new non-folded traps of hydrocarbons (HC). As estimated, these traps contain over 75% residual resources of hydrocarbons of Dnipro-Donets depression (DDD) [1]. So, the forecast and discovery of these traps is very important for increase of the resource base of the gas industry of Ukraine.
For this purpose we developed the complex methodology based on paleotectonic, paleogeographical methods, lithofacies analysis, detailed correlation of its sand tylosis reservoirs according to data of borehole geophysics (BGP) and high precision 3D seismic survey.
A new method was successfully tested in the West Solohivske Structure which had been well surveyed by drilling and had the detailed 3D seismic survey. The structure is located in the DDD axial zone and associated with the Solokha-Dykan anticlinal trap. In oil and gas relation the West Solohivske Structure belongs to Glynsk-Rozbyshiv oil and gas area.
The Upper Visean stage terrigenous deposits are regionally oil and gas bearing in the DDD axial zone [2].
Fig.1. Overview map (fragment of DDD structural tectonic map, С1v2)
Fig. 2. Paleotectonic reconstruction of Upper Visean Deposits along the line of wells 69-82-107
The industrial deposits of Upper Visean formations from B-14 through B-18 are found in the structures of Solokha-Dykan trap. The majority of deposits are associated with folded lithologically limited traps, a part of which has tectonic and stratigraphical shielding, i.e. the lithographical factor of these deposits plays the key role in formation of oil and gas deposits [3].
In the West Solohivske deposit of the Upper Visean Productive Complex (XII microfaunal bed) there are combined, lithographic and tectonic shielding gas-condensate field (GCF) associated with terrigenous deposits of coastal-maritime genesis. The productive beds are formed by sand layers of the depth from 1 m to 24-30 m, the effective porosity is 7-14% according to laboratory surveys.
The favorable conditions for formation of sand accumulative bodies with which the non-folded Upper Visean traps on DDD axial downfolds may be associated are considered in some scientists works (L.N.Botvinkina, V.S. Yablokov, 1963; A.P. Feofilova, M.L. Levenstein, 1963; I.V.Vysochansky, 1986., M.I. Machujak, 1989, O.V. Bartaschuk, 1994; etc.). According to these surveys, when the DDD axial part in late Visean time started to fold down the sea covered the central part of the Dnipro Graben where the marine conditions with alteration of regressive and transgress phases of sedimentation were formed [4]. Within its limits, especially at peripheral parts of structures, in Visean paleobasin there were formed the accumulative bodies of coastal-maritime genesis:
longitudinal shore banks, banks of internals seas and bars. (V.F. Shulga, 1981; V.I. Yakymovych, 1985; J.G. Lazarchuk, 1994; O.V. Bartaschuk, 1996). During the periods of marine transgressions and related temporary periods of growth cessation of anticlinical structures the more deep-sea open marine clay sediments covered the accumulative sand bodies on downfolds resulting in the situation when the prospective reservoirs of accumulative bodies were covered up by thick clay caprocks. Thus, a number of clinoform bodies which created conditions for formation of non-folded Upper Visean traps [5].
Geological characteristics of survey area
The reinterpretation of geo-physical materials of previous years in West Solohivske deposit (O.M. Tyapkina, L.O. Bartaschuk, 2011) contributed to specify the structural tectonic model of the reflection horizon area from base of deposits of Lower Visean stage Vв3-п (C1v1) to base of deposits of Bashkirian Stage Vб2
3-п (C2b) including, delineate the salt body and restore the conditions of sedimentation under the results of paleotectonic survey.
Concerning tectonic characteristics, the West Solohivske deposit is located in the Central Part of the Dnipro Graben (fig. 1) featured by the considerable depth of burial of crystalline basement (9–11 km), high power of sediment cover and manifestation of salt tectonics.
The deposits of lower vise– ХІV microfaunal horizon (Vв3-п) the West Solohivske anticlinal structure is the fold of organogenic structure in the deposits of the XV microfaunal horizon which was formed on the bench of the western part during Tournaisian period and was burned in the lower Visean Deposits of ХІV Microfaunal Horizon. It is proved by transgress covering the organogenic deposits of XIV microfaunal horizon, reduction of thickness of folding and increase of thickness in the central part of the area due to salt outflow in Bakeyrian boss and formation of compensative sinking basin.
Behind the Upper Visean Deposits (XI, XII, XIIa microfaunal horizon) the West Solohivske structure is not manifested as closed, it is covered by Anteupper Visean surface of misalignment and it corresponds to a spacious north-western plunge of the Great Solohivske fold. The West Solohivske structure is separated from Solohivske fold by the system of transverse dumped deposits along all the horizons of carbon in the area of Bakeyrian boss. The western flank dips along the structure axe in Upper Visean section are gradually reduced: from 10– 12° – near Bakeyrian boss, upto 4–5° – in central part of structure.
Thus, there are two basic phases of formation of West Solohivske structure – Turne-Lower Visean and Upper Visean Serpukhiv. At the ancient stage of development in conditions of local compensative basin there were formed the deep marine dark terrigenous carbon deposits with high content of organic substance. At the second phase on the basin place there is continuous periclinal of Solokhivske anticlinal structure. During this period there was, primarily, coastal marine sedimentation characterizing by terrigenous complex of deposits – alternation of aleurolite-siltstone and clayed bands.
In wavefield of Upper Visean deposits (XII, XI) on peripheral parts of West Solokhivske structure there are fixed clinoform objects. They may be associated with transgress imbedded sand bands of producing horizon from В-20 through В-14. These geological features are favorable for formation of non-folded UV traps on structure slopes.
Traps definition methods
The main object of studies was producing horizon В -17 of XI microfaunal horizon of Upper Visean substage. Lithographically the horizon В-17 is represented by quartz sandstone of 5 - 24 m depth. The deepest are wells 107, 111, 62 (see Fig. 2 and 3). It was tested in well 107 ( К п – 7–9%, Кнг-85-93, Неф-16,6), where there was received the gas influx at the rate of 101,2 thousand m3/day; it located on southern wing of structural high. In well 64 located in apical part of structure, there was not formation fluid influx from this horizon. In many other wells the horizon В-17 was BGP picked, generally as sealed with porosity below the limit value for visean rocks – 7%, only in well 69 it has porosity 7,1–7,4%, but it is characterized as water inundated. In other wells the horizon В-17 was not BGP picked and was not tested.
Fig. 3. Paleotectonic reconstruction of Upper Visean Deposits along line of well 100–66–107–62–111–61
There was conducted the detailed correlation of producing horizons where a particular attention was paid to producing horizon В-17 [6]. It was found a complex structure of these lithologic bands: it consists of several aleurolite-siltstone layers, having rather non-sustained character of development in section and area. As a result of detailed correlation there was established the stratigraphic belonging of productive object found in well 107 to the upper layer, namely the sand layer B-17A (Fig. 2 and 3).
Then, in the area of each well we observed the wave field for its stratigraphic correlation. Within the stratigraphic horizons there was executed the detailed BGP association, namely gamma ray log curve GK, to the wave pattern of productive sandstone and B-17 (see Fig. 2 and 3) in the time dimension using vertical seismic profiling (VSP). For each well there was mapped and analyzed the GC curves with wave pattern (see Fig. 2 and 3) and identified axle-phase, which is associated with stratum B-17A in the well 107. The sizes of the detected seismic object ranged from 10 to 25 ms, which is within one phase.
The seismic phase belonging to stratum B-17A in well 107 has excellent features compared with other parts of the section in other wells within the range of interlayer B-17A and is defined as positive with high amplitudes (see Fig. 2 and 3). On “Inline 80” it is clearly showed how seismic phase extends as bright spot from south to north in the vicinity of the folded “Xline 335”, where polarity changes and amplitude decreases (Fig. 4). “Xline 261” presents the bright positive phase extending from west to east to “Inline 117” where polarity changes and dynamic reflective characteristics decrease (Fig. 5).
Based on the correlation there was built time and depth maps productive stratum B-17A of West Solohivske area. Also there was drawn a map of the thickness of layers B-17A in all wells of the field. Based on the time card within the time window of length of 15ms up and down from time-correlated surface layer of B-17A built wave field attributes - RMS (Root Mean Square) of mean square amplitude of the wave field. For clarity all these constructions are combined into a single map (see Fig. 6 and 7). These attributes of the wave field have enabled to define the accumulative body, which is clearly distinguished by high values of RMS amplitude. The map shows the accumulative body popular in South Western Part of West Solokhivske Periclinal. Behind the sandstone of В-17A it is seen that its most part are concentrated in South Western Part of Structure with tendency of increase of depth from 8 m in North East and up to 23 m – on South West in the direction of Ordaniv depression. It proves the high dynamics and intensive accumulation of terrigenous material in this part of West Solokhivske structure.
Fig. 4 Section of PreStack of time migrated cube “Inline 80” through well 107
Fig. 5. Section of PreStack of time migrated cube “Xline 261” through well 107
According to data of laboratory studies of drill sample in well 107 in the sampling interval 4565–4573 m (l – 3,2 m), which stratigraphically belongs to horizon В-16 в-г, the rock is: 2,5 m – dark grey mudstone carbonaceous, in clearly defined layers - calcareous, interbedded with 5 cm microgranular limestone with fine organic detritus, slaty rock, splitted, medium and low strength, split by subhorizontal planes, easily turns into gravel; 0,7 m – light gray siltstone with interbedded carbonaceous subhorizontal planes, at the bottom of layer with a layer of light-gray fine-grained durable thick limestone of 0.15 m; rock is strongly cemented, splitted in subhorizontal planes by platy parting.
In the sampling interval 4676-4678 m (l - 0,7 m), which is stratigraphically belongs to horizon B-18, the rock is represented as follows: mudstone is dark gray to black, fine micaceous, split by subhorizontal planes. In the middle part, the sandstone layer (0.2 m) is light gray, fine-grained, strongly cemented, fine micaceous; rock with existing bedding, split by sub-horizontal planes, 0.6 m - sandstone is light gray, fine-grained, strongly cemented with millimeter layers and different amplitude suturo-stylolite seams, filled with char-micaceous and micaceous substance; subhorizontal bedding and under ∟25–30°; 6,4 m – mudstone is dark gray to black, thin-micaceous with rare prints and rare plant detritus millimeter sandstone layers described above.
Drill sample selected from water saturated parts of horizon B-17 in wells 62, 66 and from sealing parts in wells 61, 65, 102. From the saturated parts the drill samples are gray and dark gray quartz sandstone, fine-grained, fractured, dense, sometimes clay with thicknesses of individual layers and layers of 0,2-7,3 m. The sandstone is alternated with black claystone of 1,2–4,2 m and thick micaceous dack gray silt stone of 0,8 m. The effective porosity of sandstone 1,8–9,4% (in average 5,5%), openness 0–9,76×10-15 m2 (in average 2,95×10-15m2). From the sealed parts in drill sample there are claystone which are dark grey to black, micaceous, sealed, with horizontal lenticular bedding of 0,4–4,5 m, with particular layers of sandstone which are grey, fine-grained, dense. In wells 61, 102 the drill sample was not studies because of reservoir absence, and in well 65 one sample of sandstone has effective porosity of 1,4 % and openness 0.
The data of analysis of drill sample proves that in Upper Visean period, especially during formation of horizons В-18, В-17 and В-16, there were primarily coastal marine conditions of sedimentation with rhythmic alteration of coastal marine and open marine facies as coastal banks, banks of inland seas, coastal spits walls, beaches and behind-bank lagoons.
Fig. 6. Structural map, thickness and root-mean-square amplitude of wave field RMS (Root Mean Square) of sublayer В-17а
According to results of analysis of characteristics of GK curve and analysis of morphology of sand body [7] there was established the facial nature of sandstone producing layer B-17a. Model of GK curve is formed by sloping roofing line complicated by serration and horizontal direct line of plantar line. The anomaly width is 23m. The largest deviation curve belongs to the bottom part of anomalies. This is due to the fact that the energy levels of the
aquatic environment varied from very high in the beginning to low at the end of the formation of sand body, so the amount of clay material to the top of the section increases. Sediments of transgress along coastal bank in the further development of regression are overlapped by behind bank lagoon sediments. At the section (see fig. 2 and 3) there are observed the alterations of transgress and regressive stages of coastal marine sedimentation with rhythmic alteration of facies of banks and behind banks lagoons, this fact is proved by carbonaceous residues and residues of fine organic detritus (based on analysis of drill). According to morphological features the sandstone body of transgress bank has convex lenticular shape in section, in plane the body has a complex elongated from northwest to southeast irregular shape (see Fig. 2 and 3): 4 km long and 1.3 km wide.
So, there was identified the genesis of producing layer B-17a on the southern periphery of the West Solohivske structure. The sand body is facially transgress coastal bank associated with ancient inland sea that existed in Upper Visean time and was separated in the northeast by extended small water marine fine-grained silt and clay sediments of lagoon facies, and to the south it was separated by clayed marine sediments of Yaroshinsky depression.
Banks of this type are often found on shoals associated with folded uplifts of anticlinal parts, expressed in seabed relief. Examples of these banks are modern islands and shoals, developed in the northern part of the Caspian Sea. The most common of these is island Kulaly that is the lunar bank, and island Chechen, composed of two sickle banks that separated the inner lagoon [7].
So, on the basis of West Solokhivske structure shows that sand bank bodies may be also widely developed and distributed on periclinal of developed structures along Yaroshinsky and Ordanivsky depressions, as well as other depressions DDD.
For the first time due to use of new complex method of forecast and finding the non-folded UV traps on the slope of Yaroshinsky depression there was defined and identified the bank body. The results of the surveys in Upper Visean deposits it is forecasted a new deep zone of oil and gas accumulation on slopes of Yaroshinsky and Ordanivsky depressions. The next phase of works should be the estimation of prospects of oil and gas content of Upper Visean Deposits, as well as improvement and increase of effectiveness of method of forecast of non-folded objects. To identify the forecasted area of oil and gas content it is recommended to set a new 3D seismic survey in the peripheral areas of proven deposits with further study of the deep slopes of axial depressions of Dnipro graben.
Fig. 7. Structural map, thicknesses and root-mean-square amplitude of wave field RMS (Root Mean Square) of sublayer В-17а
Список літератури
1. Гавриш в.к. Методика прогнозирования комбинированных нефтегазоносных ловушек (на примере Днепровско-Донецкой впадины) / Под ред. П.Ф. Шпака, В.К. Гавриша. - К: Наук. думка, 1982. - 196 с.
2. Витенко В.А. История и нефтегазоносность структур Днепровско-Донецкой впадины / В.А. Витенко, Б.П. Кабышев // - М.: Недра, 1977.
3. Височанський І.В. Стратиграфічні пастки вуглеводнів і методика їх пошуків // Питання розвитку газ. пром-сті України: Зб. наук. праць. - Х.: УкрНДІгаз, 2001. - Вип. ХХIХ. - С 175-184.
4. Височанський І.В. Нові аспекти систематизації нафтогазоносних структур / І.В. Височанський, М.П. Зюзькевич // Питання розвитку газ. пром-сті України: Зб. наук.праць. - Х.: УкрНДІгаз, 1999. - Вип. ХХVII. - С 113-116.
5. Бартащук А.В. Особенности геологического строения и перспективы нефтегазоносности глубокопогруженных нижнекаменноугольных и девонских горизонтов южной краевой зоны Днепровско-Донецкой впадины// Автореф. дис. ... канд. геол.-минерал. наук. - М.: ВНИИГАЗ, 1994. - С. 16.
6. Коломієць Я.І. Уточнена синоніміка регіонально-газоносних горизонтів нижнього карбону та перспективи їх газоносності у південно-східній частині ДДЗ та північно-західних околицях Донбасу / Я.І. Коломієць, А.В. Лизанець, А.А. Лагутін, О.С. Міносян // – Х.: УкрНДІгаз, 2003. – 86 с.
7. Муромцев В.С. Электрометрическая геология песчаных тел литологических ловушек нефти и газа. – Л.: Недра, 1984. – 260 с.
Authors
Yevdoschuk Mykola Ivanovych
Head of Department of Coal Deposits Geology of Institute of Geological Sciences of National Academy of Sciences of Ukraine
Доктор геологічних наук, професор
Bartaschuk Leonid Oleksiyovych
Postgraduate student
Institute of Geological Sciences of National Academy of Sciences of Ukraine
Geology domain QA Engineer at Luxoft
M. Marukhnyak celebrates his 80th Anniversary
Marukhnyak was born on October 27, 1933, in Khodovantsi village, Tomashiv Region, Lyublin province in Poland in rural family.
In 1945 the Ukrainians who lived on Chelm Land році were evacuated, in fact, deported to the Soviet Ukraine from where the Marukhnyaks moved to Lviv (Shyrets city) oblast from Odesa oblast because of 1946-1947 famine. Here he finished secondary school and entered Lviv Polytechnic Institute, geological faculty.
First labor steps were made at Tuymasyn oil deposit in Bashkiria, then since 1960 he started his scientific activities in the Central scientific research laboratory of Production Association ‘Ukrnafta’. In 1969 he defended the thesis, then he was invited to the Ukrainian State Scientific Research and Design Institute of Oil Industry in Kyiv.
Fifteen years of twenty years of activities in this institute (1970-1990) Mykola Yosypovysh was Deputy Director in Science in Geology and Drilling.
His scientific works are dedicated to justification of ways of development and increase of resource hydrocarbon base of oil industry of Carpathian, Dnipro-Donets, Azov-Black Sea, Baltic regions, defining the prospective directions of surveys, as well as coordination of
geological works in boundary regions of states of Council for Mutual Economic Assistance: Poland, Czech Republic, Hungary, Germany, USSR.
During this period due to Marukhnyak there were developed long-term complex projects related to industrial development of hydrocarbons resources of oil and gas regions of Ukraine, Byelorussia, Kaliningrad Oblast, Lithuania and Latvia.
During seven years (1983–1989) he chaired a group of specialists of institute ‘UkrDPROnafta’ engaged in design of development of Cuban deposits Varadero and Boca de Haruko. Due to these woks the volumes of oil production in Cuba doubled during 5 years and achieved 1,000,000 tons per year.
In 1990, Marukhnyak was sent to Algeria where he chaired a group of soviet specialists who provided scientific technical assistance to Algerian national company ‘Sonatrak’ during development of hydrocarbons deposits, including giant oil Hasi-Messa-Ud and gas Hasi-Rmel deposits.
After return he worked at some responsible posts in the State Committee of Oil, Gas and Oil processing industry (1993–1998) and National Joint Stock Company ‘Naftogas Ukraine’ (1998–2002).
Today, Marukhnyak cooperates with Private Joint Stock Company ‘Scientific Research and Design Bureau of Drilling Instrument’ in solving the new technologies of development of oil and gas deposits by drilling of horizontal wells, as well as renewal of obsolete wells by side tracks.
During 15 years he was a member and an expert of the Central Committee on development of oil, gas and gas condensate deposits at the Ministry of Oil and Energy of Ukraine, he is the pioneer of some oil deposits of Pri-Carpathian and Dnipro-Donets cavity, he has over 130 published works, including monographs, brochures, scientific articles, author’s certificates for inventions, geological and overview maps.
Marukhnyak is awarded with several soviet medals, distinctions and certificates. He is honorable specialist of industry of Ukraine, current member of Ukrainian Oil and Gas Academy of Sciences.
OIL AND GAS GEOLOGY
Trends in changes of reservoir properties of the rocks of Sarmatian stage at the northwestern part of Bilche-Volytsa zone in different
facial terms of sediment accumulation
UDK 553,982
© V.M Vladyka Lviv comprehensive research center of UkrNDIgaz A.O. Push Expert of DKZ of Ukraine for Industrial Geophysics M.Y. Nesterenko Dr. of geol. science R.S. Balatskiy Lviv comprehensive research center of UkrNDIgaz
On the basis of geophysical well logging data the physical properties of reservoir rocks formed in different facial conditions (deep-water, transitional, shallow-water) were characterized depending on selected types of cross-sections in Sarmatian deposits.
Key words: reservoir rock, porosity, permeability, factors of layering, sandstone, transgression and regression of the sea.
A complex of well logging actions (WL) allows describing various properties of natural bodies, i.e. the electrical resistivity of various parts of the reservoir, the natural and given radioactivity, natural polarization and rate of passage of elastic waves, in a flexible manner. All parameters of these methods are geological indicators which allow studying the conditions of sediment accumulation in rocks.
The development of a sedimentic logging analysis technique based on well logging methods has been the task of the Dr. of geological-mineral sciences, T.S. Izotova for many years. However, these works have not been completed for objective reasons. In the northwestern part of Bilche-Volytsa zone (BVZ) T.S. Izotova identified four types of cuts. [1]
The authors of this article, based on joint research of WL techniques and detailed descriptions of microfaunal research, conducted the further in-depth study of the conditions of sediment accumulation in the northwestern part of BVZ. For this purpose, the most representative coring intervals selected by core sample and microfauna were selected in wells, which revealed the Sarmatian deposits. On the basis of these studies, three types of cuts were identified.
A characteristic feature of the Sarmatian deposits is variation of capacity of individual packs and layers caused by the sediment accumulation conditions and intensity of terrigenous material arrival to the pool. Depending on the base level of erosion, the sandstones were deposited not only in the humble areas of relief, but also in the high-ground vaults, elevations and slopes, underwater shafts, spits, bars, and this is due to the unevenness of their distribution in the area [2, 3].
The first type of cut is the deepest part of the shelf. This type of cut includes the Sarmatian sediments of Vyzhomlya and Vyshnya fields, as well as Shehyni and Oselia areas (see the figure).
The second type of cut is a shallow shelf. This type cut was open in Sarmatian deposits in Letnany, Kniahynychi, and Pynyany fields (see the figure).
The third type of cut is the coastal part, the transition to Verhnia Dashava and Nyzhnia Dashava deposits. Because of the small amount of information, this type of cuts is little studied. It was open at Rubanika and Rudky fields (see the figure).
The formation of microlayered Sarmatian cuts occurred in certain sedimentation conditions affecting the texture, structure and lithological composition of layers. These genetic features of the cut are determined using the WL methods based on parameters of the stratification, coefficient of frequency change of lithological varieties and sandy factor.
The stratification of Sarmatian section is the result of changes in facies and hydrodynamic regimes of sedimentary flows. Each layer in the microlayer cut allocated according to the WL data meets certain deposit sedimentation conditions.
The texture of a certain pack of the microlayered cut can be determined by studying the individual strata of different lithology and thickness. The cut stratification coefficient (hL) is determined through the total thickness of all layers Σ hi and the number of all layers (n): hL= Σhі /n.
As regards the value of the stratification coefficient (hL), the cuts are divided into thick-layered hL >4, medium-layered hL from 4 to 2, thin-layered hL - from 2 to 0.8 and microlayered hL <0.8 m.
According to the stratification coefficient, the cuts of Sarmatian rocks in wells of Vyshnia, Oselia and Shehyni areas can be attributed to thin-layered. The cuts of wells in Zaluzhany, Mayne and Letnyany areas (see the figure) belong to the medium-layered.
An important texture feature of the layered deposits is the coefficient of the frequency of change of individual lithological varieties of rocks (K L):
where hi· η is the product of the average thickness of layers of individual lithological units and their percentage content (η) in the whole pack.
To determine the frequency of changes in lithological varieties of rocks, it is required to know the η value. This indicator is defined as a percentage number of an individual lithological size, and its percentage content in relation to the total number of all lithological varieties in the pack.
In terms of lithological changes, the rocks are monofacial and polyfacial. If the coefficient (КL)≥0,8, the deposit sedimentation conditions are stable in a certain period of geological time span. If КL<0.8, indicates the continuous change in lithological varieties of rocks and a sharp change in deposit sedimentation conditions.
The sediments of Sarmatian rocks are the examples of such changes. The stratification of sandstone, mudstone and siltstone is changing continuously. For example, in Shehyni well 2 (interval 960-1100 m) КL=0.3, in Oselia well 1 (interval 1100-1300 m) КL = 0.12; and at Vyshnia well 5 (interval 940-1040 m) КL=0.1.
The distribution of sandy rocks laterally, according to the WL data, in microlayered cuts is investigated using the sandiness coefficient (KSands). This figure is one of the major ones for zonal and local forecasts in productive saturated cuts.
In terms of sandiness, the microlayered rocks, based on the WL data, are subdivided into three groups: with mostly alevritic rocks KSands=ΣhSands/Σh>0.5, with an average sandiness level KSands=ΣhSands/Σh from 0.5 to 0.3; and with mostly clay rocks KSands=ΣhSands/Σh<0.3.
In sections of Sarmatian sediments the clay rocks are predominating, e.g. Shehyni well 2, KSands= 0.06; Oselia well 1, KSands= 0.04, Vyshny well 5, KSands=0.08. The most arenose cut (according to WL) is located in the interval of 1250 to 1350 m, Vyzhomlya well 2. The sandstone layers are clearly distinguished by GC method. The cut sandiness coefficient is 0.7, confirming the inflow of gas into the well (Qg= 12.2 thousand m3/day).
In the context of the shallow shelf part, the sandiness coefficient (Csand) according to Zaluzhany well 30 is 0.55, at Maynychi well 7 is 0.72, and at Letnyany well 10 - 0.68. The amount of sandy material in these cuts is much higher.
The sediment logging analysis involves identification of the structure of sedimentary rocks. As regards the structural features, the logging methods determine the particle size distribution of sandstones, siltstones and clay dispersion degree.
The indicators of well logging methods, i.e. a lateral micrologging (LML), lateral logging (LL) and lateral logging sensing with small probes (LLS), are formed in the permeability area. Based on their values, we can determine the area permeability depth, the porosity rate and other elements characterizing the permeability area. After determination of the porosity parameter according to WL, the changes in the mean diameter of the grains of sand and alevritic rocks can be described.
Using the LML methods and micrologging (ML), together with an average diameter of sandstone grain, the conclusions can be drawn about the signs of the basin regression or transgression. Dsir (ρmbk) reduction suggests the transgressive events in the accumulation of rocks. Dsir increase or change (ρmbk) vertically indicates the signs of the sea regression.
The uneven distribution of clayness in rocks and uneven grain size of the sandstones indicate the rapid streams. The complex of the a in the northwestern part BVZ with a sufficient probability.
Fig. Typical cuts of the Sarmatian deposits formed in various deposit sedimentation conditions
The first type of cut
The figure shows a typical cut of Sarmatian rocks at Vyshnya area. It is the deepest part of the shelf. The cuts are characterized by thin-layered texture of rocks. The layers 1 to 0.4 m, with high value of the natural radioactivity of rocks 8-12 γ, and layers of both regressive (Vyshny well 5, interval of 1300 to 1250 m) and transgressive (Vizhomlya well 13, interval of 1340 to 1360 m) types are predominating.
The electrometer recorded the cycled nature of deposit sedimentation in wells; there are significant megacycles (Vizhomlya well 13, interval of 1370 to 1270 m). The pack of argillaceous rocks (4 m) is varied, alternating with sandstones and siltstones in the interval of 1270 to 1210 m. The megacycles are ending with a large stack of argillaceous rocks. The cut s sandiness coefficient is from 0.04 to 0.08. The sandiness is extremely variable. The most sandy cut is located in Vizhomlya well 3 (interval of 1250 to 1350 m), where KSands=0.7. The apparent resistance of rocks is 2 to 5 ohm·m. Judging by SP self-polarization curves, the cut is clearly differentiated (Vizhomlya well 13, interval of 1200 to 1350 m).
The cut clay content is very high. The collector rocks have the clay content up to 30%. The mean clay content coefficient Shl at Vizhomlya deposit is equal to 21%.
As regards their granulometric composition, the sandstones in the recessed shelf are medium and fine-grained. The statistical analysis of the data shows that the medium-grained component (from 0.5 to 0.1 mm) holds a 29.6% share, and a fine-grained component (from 0.2 to 0.01 mm) holds a 30% share. The content of clay shares is up 38%, and the carbonate shares are 31%. The carbonate cement occurs in the amount of 11-22%. Its mean value is 18.5%. These are the sandstones of alevritic, medium-clay lithotypes with carbonate cement.
The rocks with open porosity ratio of 7 to 15 are the most common. There are very little sandstones with porosity of less than 7 and more than 20%.
The second type of the cut of Sarmatian rocks was formed in shallow shelf. These cuts are significantly different from the cuts, which were formed in the most recessed shelf (see the figure).
The first difference observed using the well logging methods is the nature of rock layers. While the cuts of Vizhomlya-Shehyni area are composed of alternating sandstones, siltstones and mudstones, in the cuts of Letnyany-Zaluzhany type the sandstone and siltstone is more prevalent, but there is almost no mudstone layer. The second difference of cuts is in the thickness of layers to their inherent micro- or thin-layered nature. The cuts of Letnyany-Zaluzhany type are characterized by layers of greater thickness, which varies from 0.6 to 2 m.
The WL methods in these cuts are better differentiated. The "own polarization" (OP) method allocates well the reservoir rocks in the cuts (Maynychi well 7, the interval of 2250 to 2350 m). The Kniahynychi-Pynyany cuts are somewhat different from Letnyany-Zaluzhany type by their cycles. The cycles observed in Kniahynychi-Pynyany cuts are less powerful than Letnyany-Zaluzhany cuts (Kniahynychi well 1, the interval of 2150 to 2050 m, Maynychi well 7, the interval of 2240 to 2460 m).
The clay packs delineating the sand and silt are clearly distinguished by means of WL and retain the thickness of 10 (Zaluzhany well 30, the interval of 2645 to 2660 m) to 20-30m (Knyahynychi well 1, the interval of 2140 to 2165 m).
The cuts of Letnyany-Zaluzhany- Kniahynychi types are combined by the low clay content in rocks. In the sandstone of the second type of cut the clay content reaches 10-15%. They have a high content of sand component (KSands>0.5). Their thicknesses in stratification represent 0.6 meters or more. The sandstones in these sections (according to the logging data) have larger grains (Dsir to 109 microns) and a large filtration area (up to 8d) affecting the interpretation of well logging techniques. Due to this effect, the apparent electrical resistance on PivotChart varies from 5 to 9 Ohm·m; in natural radioactivity is 4 to 8 u, the interval time of elastic wave passage in reservoirs (AT) varies from 204 to 240 mcs/m.
As regards the sandiness coefficient, the most sandy horizons are ND-1-10 at Letnyany and Pynyany fields. ND-10-15 horizons in these fields are represented by cuts dominated by siltstones, with a small number of highly porous sand strata.
In Letnyany field the porosity ratio varies from 14.9 to 25.2%; the most common open porosity factor is 15.8 to 16.8% and the average gas permeability is about 0.2·1015 m2. The deposit in the Nyzhnia Dashava deposits on Letnyany field lies in the interval of 800 to 1200 m.
In Krukenytsia basin, in Kniahynychi well 1, in the interval of 1540 to 2414 m the lower Sarmatian deposits have the porosity ratio of 7 to 17%, and the permeability coefficient of 0.1·1015 to 1·1015 m2.
The third type of cut
An example of this type of cut can be the cut of Sarmatian sediments at Rudky and Rubanivka deposits (see the figure), which has its special characteristics.
The deposit sedimentation conditions of the lower Sarmatian sediments in this section are different from the deposit sedimentation conditions in cuts of the first and second types. The Rubanivka and Rudky deposits are located in the junction of northwestern part of the Eastern European Platform and the Outer zone of the Carpathian foredeep.
The Verhnia Dashava and Nyzhnia Dashava deposits occur here at shallow depths. The WD horizons have a thickness of up to 600 m, the ND horizons are from 600 to 1100 m. The Verhnia Dashava deposits are much pirytyzed (Rubanivka well 6, the interval of 440 to 550 m). The transition from the Verhnia Dashava and Nyzhnia Dashava sediments is clearly recorded by GK and PS methods.
The electric method curves show the sedimentation changes from the Nyzhnia Dashava to Verhnia Dashava sediments as clearly recorded by differentiation curves. The Verhnia Dashava deposits are little or not at all differentiated inside the microlayered packs. In contrast, the Nyzhnia Dashava methods are well differentiated (Rubanivka well 6, the intervals of 520 to 550 and 640-660 m) are also well differentiated by RK curve. The Verhnia Dashava sediments clearly show the sandstone (interval of 640 to 660 m) and clay (interval of 630 to 640 m).
As regards the textural features, the fine-grained sandstones of the Nyzhnia Dashava deposits with thicknesses of hPr 0.8 are 4cm. There are layers 0.15 to 0.2 cm thick. The Nyzhnia Dashava deposits are fine- and medium-grained, well sorted. The open porosity coefficient is 7 to 13%.
In Rubanivka field, horizons VD-12 and ND-1 to ND-6 are productive, and in Rudky field ND-5 to 7 horizons are productive. The apparent electrical resistivity of sandstone reservoir rocks is 4 to 7 ohm·m. The natural radioactivity of reservoir rocks of the Verhnia Dashava sediments reaches 7 to 11 γ, and the Nyzhnia Dashava sediments reach 3 to 6 γ.
Thus, the focused petrophysical studies of reservoir rocks in combination with the well logging data for the Sarmatian stage of the Carpathian petroleum province, depending on the selected facies (cut type), are a promising direction for further research.
List of References
1.Yzotova T.S. Definition of genetic types of sedimentation rocks according to the well logging data / T.S. Yzotova, A.E. Kulynkovych, A.O. Push [et al.]. - Lviv: UkrNYHRY, 1986. - 58 p.
2.Carpathian petroleum province / V.V. Kolodiy, G.U. Boyko, L.E. Boychevska [et al.]. - Lviv-K.: Ukrainian Publishing House LLC, 2004. - 390 p.
3.Scherba A.S. Lithological-facial peculiarities and collection features of oil and gas deposits of the External zone of the Carpathian foredeep / A.S. Scherba // Geology and geochemistry of combustible minerals. - 1986. - Vol. 67. - P. 33-39.
Article Authors
Vladyka Vitaliy Mykolayovych
Head of Lviv comprehensive research center UkrNDIgaz. He graduated from the Lviv National University "Lviv Polytechnic" (an engineer-technologist) and Ivano-Frankivsk National Technical University of Oil and Gas (mining engineer of oil and gas). The range of scientific studies comprises the development of hydrocarbon deposits, layer physics.
Nesterenko Mykola Yuriyovych
Senior research fellow of Lviv comprehensive research center UkrNDIgaz, Doctor of Geological Sciences. He graduated from the Geological College of Kyiv, Ivano-Frankivsk Oil and Gas Institute (Geological Faculty, the specialty of the mining engineer-geologist). The range of his research interests is oil and gas geology, layer physics, petrophysics. He is the author of about 70 scientific publications, 10 invention patents, and six industry standards of Ukraine.
Balatskiy Roman Stepanovych
Junior Research Fellow of Lviv comprehensive e research center UkrNDIgaz. He graduated from the Lviv National University of Ivan Franko (Geological Faculty, with the major in geological survey, search and exploration). His research interests include the oil and gas geology.
OIL AND GAS GEOLOGY
Improvement of the effectiveness of hydrodynamic system data interpretation by constructing the rocks distribution chart
according to the type of cement
UDК 553.982 ©Ya.M. Koval
For reservoir rocks with clay-carbonate type of cement replacement clay cement into carbonate leads to error of determination the calculation parameters defined by logging. The authors proposed to build a map of the location of areas with different distribution of clay-carbonate and carbonate-clay cement. This map will enable to optimize the choice of petrophysical models for estimating reserves of hydrocarbons in areas with predominant content of clay or carbonate cementing material.
Key words: well logging, calculation parameters, productive sediments, clay-carbonate cement type, map.
One of the factors that determine the physical properties of the reservoir and considerably affect the parameters of geophysical fields is lithologic and structural characteristic of rocks.
True rocks are complex heterogeneous systems, each component of which is characterized by considerable variability even within the same geological object. Therefore, a detailed classification of irregularities with appropriate level of reality is possible just only for single horizon namely is very individual. The application of research results of the appropriate horizon on lithological heterogeneity to characterize the other horizon without additional adaptation can lead to considerable incorrectness in the interpretation of the results of geophysical studies of wells.
The heterogeneity of rocks must be considered relative to its impact on the physical field whereby is conducted research of geological fields, taking into account the content of solved tasks.
Heterogeneity present in the layers of rocks is possible to classify according to various criteria, but there are common approaches to the study of lithological heterogeneities of rocks.
According to the value of the heterogeneity properties demonstration will be indetified micro and maсro- heterogeneity of the environment.
Maсroheterogeneity characterizes the deviation of microelements of the rock in its location to the system (ideal) location and parameter dispersion that describe this microelement. Considering the miсroheterogeneity, we can talk about some microelements such as grain of mineral skeleton (their relative position, shape, size, density, chemical composition, etc.), reservoir pores( their shape, size, relative , etc.), fractures (they openings, direction, density, location, etc.), the nature and properties of the saturating fluids. Most of the tasks solved by geologists at the oil and gas fields associated with miсroheterogeneity of reservoirs. Parameters reflecting miсroheterogeneity of layers can be determined by borring and laboratory studies.
Fig. 1. Comparison of specified value of clay fraction water saturation for reservoir rocks Dн with their resistance on contact logging ρБК
Maсroheterogeneity characterizes the deviation of rock macroelements in their location to the system (ideal) location and takes into account the size of such macroelements, propagation direction, shape and so on. Maсroheterogeneity can be traced hardly, using studies made only in one well, and generally can not be traced by petrophysical studies. Only the presence of complex geophysical studies in a large number of wells can be the basis for the identification and study of existing maсroheterogeneity.
In the direction of property changes within the investigated environment can be determine vertical, radial and azimuthal heterogeneity. Characteristics of any environment, including mixed, are the physical and geometrical parameters. Physical parameters are physical quantities that reflect the properties of individual business areas (some fields of penetration areas of drilling fluid in the reservoir, the separate layers in the pack layers, etc.). Geometric parameters reflects the structure of the studied geological object. These parameters include the thickness of the layer, the thickness of the clay cover, propagation direction, etc.
Characteristics of any geological object consists of a description of its features and the type relationship between these properties. Sedimentary rocks reservoir, which contain hydrocarbons are described under many parameters. But some properties are important, others are less significant. To determine the calculation parameters of reservoir rocks the one of the priorities is to determine the type of cementing material and its distribution along the field.
The capacitance and filtration properties of rocks and petrophysical productive capabilities that are used for interpretation of geophysical researches determine the type of cementing material and its content in rocks reservoir.
During the geophysical researches of wells will be measured an electrical, radioactive and acoustic properties of rocks associated with lithology, grain size, density, porosity of reservoir and pore fluid content. Since logging is continuous throughout the depth of the well, it is a extrinsical value for establishing of facies sequences in both small and large intervals. These data can be used to analyze changes in the conditions of accumulation of sediments, unless, of course, measurements reflect sedimetric analysis of rock but not the properties of pore fluid or other secondary characteristics.
Results of geophysical researches, in addition to capacitive-filtration properties and nature of saturation reflect the rhythm of the process of sediments accumulation, the nature of sediments occurrence, sediments accumulation rate and so on. To determine which geophysical parameter or complexe of parameters should be used for the construction of petrophysical dependencies or special distribution maps of the parameter in the area of the deposit can be achieved by the study of physical and filtration-capacitive characteristics of the rocks plays.
In some cases, to determine the characteristics of rocks is enough only one or two curves of geophysical research of the well. Examples include the use of unauthorized polarization curve (PC) in the sand-clay vertical section.
However, for the interpretation is recommended to use all available curves of geophysical research of the wells (GRW). Existence of geophysical curves of different methods allows to determine range of characteristics of rock that covers the chemical and mineral composition, structure, texture and more. The more GRW data is used, the less probability of aliasings and errors is during the interpretation
For example, we will consider Bohorodchansky gas field, on which the productive part of section is represented by the reservoir rocks of complex structure [ 1]. These rocks reservoir adequately reflected in geophysical fields measured in the well. The heterogeneity of these reservoirs caused mainly by the presence of clay and carbonate cementing mass, which being a part of the pores volume, locally reduces the effective porosity and permeability. Reservoir depending on the proportions of clay and carbonate components of rocks cement having different electrical resistance and neutron properties. Replacing the part of cement clay material with admixture of carbonate causes reduction of tightly bound water and therefore increase an electric resistance [2-4 ] and the intensity of the gamma radiation field of thermal neutrons [5 , 6] Therefore, the determination of calculation parameters of reservoirs with an advantageous content of carbonaceous material in the cement according to the electric logging data of the wells and neutron methods leads to significant errors.
The accountability of cement composition of rocks to determine the coefficients of porosity and gas saturation of reservoir is extremely limited due to the small number of studies of core material and the use of generalized models of calculation parameters is complicated by significant heterogeneity of cement fraction in productive rocks.
Thus, the determination of the cement composition of rocks and its spatial distribution according to GRW data and its consideration during the determining of calculation parameters of rock is today an relevant objective, the resolving of which will increase the reliability of calculating the porosity coefficients and gas saturation of reservoir with clay and carbonate type of cement.
Confirmation of the impact of carbonate material contained in cement rocks reservoir, on increasing of its resistance ρn, is designed diagram (Fig. 1) comparing the values of electrical resistance laterolog with the parameter values of the normalized water saturation of the clay fraction, which is described by:
(1)
where ΔІγ – double difference parameters of γ-activity; ΔІnγ –double-difference parameter of the intensity of gamma radiation field of thermal neutrons; Кп – porosity ratio
Since the natural radioactivity of rocks is determined by their dispersed properties and conditions of sedimentary basin and the intensity of gamma radiation of radiation absorption of neutrons - for hydrogen content in the rock, the parameter Dн indicates how much water is in clay cement rocks in the particular area. The parameter normalization of water saturation of rock porosity ratio clay fraction leads the parameter value to the unit volume of pore space.
Fig. 2. Drilling pattern with different distribution of clay-carbonate and carbonate-clay cement of productive unit "A" of the Bogorodchany deposit
Thus, the content of carbonates in the clay cement is the main dominant factor of changes in electrical conductivity and neutron properties of reservoir rocks in the productive complex of the Bogorodchany gas deposit.
In the work [ 7 ] is proposed a way to estimate the type of cement of reservoir rocks on the basis of the results of neutron gamma logging . It helps to determinate the type of cement (clay- carbonate, carbonate- clay) based on the criterion approach to the estimation of maximum possible hydrogen content in the reservoir with different types of cement. But it is important to know how is distributed one or another type of cement not only vertically of the productive interval, but also over the area of the deposit. This should be considered when selecting the petrophysical model for determination of calculation parameters for the newly borred wells [ 8], the refinement of neutron properties of matrix considering the prevailing content of clay or carbonate component of the cement [9] and filtration properties of reservoir rocks, etc.
Therefore, the main objective of this work is the design of drilling pattern with different distribution of clay-carbonate and carbonate-clay cement.
Fig. 3. Distribution scheme of the lifetime values of thermal neutrons in the gas-saturated rock producting packs "A" of the Bogorodchany deposit measured according to the INNK data
As it follows from the above mentioned material the layers of producting packs of the Bogorodchany deposit are characterized by variability of proportions of carbonate and clay components in cementing mass not only along the horizontal but also along the vertical section of the pack. It should be noted that, researching the producting packs by the geophysical methods, taking into account the averaged value of any geophysical parameter and that this parameter characterize the whole pack. Therefore, for accounting purposes of the type of cementing material during the calculations, for example, electrical resistance is important to differentiate the area predominantly of one or another type of cement in along the horizontal of the deposit. This differentiation is represented in the drilling pattern of the different distribution clay- carbonate and carbonate- clay cement of the producting packs "A" of the Bogorodchany deposit ( Fig. 2). It is developed by replacing definition of clay- carbonate cement with carbonate-clay cement:
(2)
where Sг/к – total area of the deposit, limited by logging opposite layers of the producting packs "A" with clay-carbonate cement.
The pattern shows that differentiation of the pack dominated by carbonate- clay or clay- carbonate cement is irregular due to the presence at the field areas with different conditions of sediment accumulation. As we can see, the north- western and south- eastern parts of the pack is characterized by predominance in the layers of carbonate- clay cement and separated aby the deposit (the wells 101, 67, 40, 121, 171, 53, 167, 168, 166, 165, 162 and 176) where in the layers, conversely, dominated the clay- carbonate cement. Also, from the pattern can be seen that in the north-east of the producting pack on the background of rocks with a predominance of carbonate- clayey cement is a local area of the reservoir with the dominance of clay - carbonate cement (the well 23 140). In general there is a tendency to dominance in the producting pack "A" in the north of carbonate- clay cement, and in the south - clay- carbonate
To confirm the accuracy of this information was designed the scheme of value distribution of the lifetime of thermal neutrons in a productive gas-saturated pack "A" of the Bogorodchany deposit obtained according to INNK data (Fig. 3). For example, the wells 121, 23, 101, 67, 121 are characterized by minimum values of the lifetime of thermal neutrons, due to the highest content of clay component of the cementing material with minimum content of carbonaceous agent, and the wells 61, 64, 129, 164 – with the maximum lifetime of thermal neutrons, primarily due to a minimum content of the clay fraction in the cementing material, and the maximum content of carbonate component.
Thus, designed drilling pattern with predominance of clay-carbonate or carbonate-clay cementing material gives a possibility to specify the type of cementing material and content therein of carbonate agent during GRW data interpretation and in order to enhance the uniqueness and efficiency of calculation parameters of complex reservoir rocks.
Список літератури
1. Сводное заключение по Богородчанскому газовому месторождению (анализ результатов геофизических исследований скважин) / В.В. Кузьменко, М.В. Николюк, В.И. Грицишин, С.Я. Бе-лик // Министерство геологии УССР, трест «Укргеофизразведка»; Ивано-Франковская промыслово-геофизическая экспедиция. -Ивано-Франковск, 1969. - 71 с.
2. Вендельштейн Б.Ю. Методические рекомендации по определению подсчётных параметров залежей нефти и газа по материалам геофизических исследований скважин с привлечением результатов анализа керна, опробований и испытаний продуктивных пластов / Б.Ю. Вендельштейн, В.Ф. Козяр, Г.Г. Яцен-ко. - Калинин: НПО «Союзпромгеофизика», 1990. - 261 с.
3. Ильинский В.М. Геофизические исследования коллекторов сложного строения / В.М. Ильинский, Ю.А. Лимбергер. - М.: Недра, 1981. - 208 с.
4. Кобранова В.Н. Физические свойства горных пород (петрофи-зика) / В.Н. Кобранова. - М.: Государственное научно-техническое издательство нефтяной и горнотопливной литературы, 1962. -490 с.
5. Ларионов В.В. Радиометрия скважин / В.В. Ларионов. - М.: Недра, 1969. - 328 с.
6. Скважинная ядерная геофизика: справочник геофизика / [под ред. О.Л. Кузнецова, А.Л. Поляченко]. - 2-е изд., перераб. и доп. -М.: Недра, 1990. 318 с.
7. Старостін В.А. Оцінка типу цементувального матеріалу порід-колекторів за даними нейтронного гамма-каротажу / В.А. Старостін, Я.М. Коваль // Нафт. і газова пром-сть. - 2011. - № 2 (256). -С. 22-26.
8. Старостін В.А. Особливості визначення коефіцієнта газонаси-чення пластів-колекторів із глинисто-карбонатним типом цементу / В.А. Старостін, Я.М. Коваль, І.О. Федак // Розвідка та розробка нафтових і газових родовищ. - 2013. - № 1 (46). - С 58-65.
9. Коваль Я.М. Використання методу нейтронного гамма-карота-жу для просторової корекції значень часу
життя теплових нейтронів у породах складної будови / Я.М. Коваль // Нафт. і газова пром-сть. - 2011. - №4 (258). - С 16-19.
Author
Koval Yaroslav Mykolayovych
Candidate of Geological Sciences, Associate Professor of of Ivano-Frankivsk National Technical University of Oil and Gas. In 2004 graduated from the Ivano-Frankivsk National Technical University of Oil and Gas. Research work associated with the development and improvement of methods of quantitative evaluation of filtration-capacitive properties of the complex reservoir rocks and development of the base of petrophysical models based on geophysical studies of oil an d gas deposits.
OIL AND GAS GEOLOGY
About some problems of the current performance of the oil and gas geological exploration (GE)
UDК 553.98.061.4 (477.6)
© M.P. Zyuzkevych
candidate of geol. science T.O.V. “Technics”
In connection with the tendency towards decline in efficiency of exploration drilling for oil and gas observed in recent years, the author analyzes the causes that should be considered when determining the strategy and tactics of the exploration process.
Key words: oil, gas, efficiency, exploration drilling, resources, DDD, Serpukhiv and Vise complexes
In the context of acute Ukraine's dependence on natural gas import were and will be an urgent question an effective use of the potential of domestic mineral resources. However, the question of increasing domestic production, even keeping its volume on the achieved level raises a serious concern.
Some pessimism, at first view, of this idea based on the results of professional observation of the process of oil and gas exploration in Ukraine as a whole, and in the eastern region in particular, which provides the bulk of domestic production.
The author still does not take into account the fact that the last two or three years, the society receives an idea avout the significant role of the so-called “shale gas” in efforts to reduce Ukraine's dependence on imports. The question is only about the effective development of the still quite large and at the same time the comples potential of traditional hydrocarbon deposits.
However, the changes in measures of the geological efficiency of the current volume of forecasting and prospective (undiscovered) resources of hydrocarbons, which part is over 40 % of the original, does not inspire a great optimism about the unproblematic extension of discovered reserves in amounts that could compensate the production and retain optimal balance between the production and discovered resources. And the question, in our view, is not only in the complex structure of the current forecast RSD resources, which leave no doubt as to their reality, and the methodical techniques of their development, often is even associated with lost by geologists guidance in identifying of effective ways of exploration. It should be noted that insufficient attention is paid to the analysis of all known factors of oil-and-gas bearing both zone and local levels when some factors (structural) overestimate and others ( lithofacies, tectonic, fluidodynamic, catagenetic) are neglected.
The fact that the structure factor of the oil and gas bearing forecast at the local level is necessary but insufficient indicate negative results for exploratory drilling of large anticlinal structures that are productive in the upper parts of the section and are deposits with significant or medium reserves (Shebelinsk, Kobziv, Zakhidno Khrestyshenk, Bilsk, Zakhidno Solokhivsk, Semyrenkivsk). It is well known that from the proven reserves of these fields should also expect considerable stocks is not supported, because of unreasonable neglect of lithofacies and catagenetic factors and is, in our opinion, another false assumption which often leads to disappointment.
An illustration of this conclusion may be the drilling results of the exploration well 250 at the Zakhidno Solokhivsk field.
The project designers of this well, eventual making sure that a clear closed anticlinal form with an amplitude of 250 m on the horizon reflecting VI (bottom C1t) is a determinative factor of the forecast, made calculation here about 42.3 billion m³ of gas category С3, 70% of which expected within the context from the B-21 to T-3.
However, the well with the design of depth of 6300 m, reaching a depth of exploration 5510m removed a carbon of lower visean (horizon B-24 -25), unfortunately, has not confirmed the designers forecast, because all part of the section is below the horizon B- 21 (i.e, the lower of the upper and open part of the lower visean) with capacity of about 700 m and is composed of clay-carbonate type of section, has no granular or fractured –vuggy value of reservoirs, and in section carbones of the lower visean (B -24 -25) on the GRW is identified two layers of limestone with an open porosity of 5-12 % filled with mineralized water. Single thin layers of conditioned collectors here have more sporadic character, and therefore have not a decisive role in the formation of commercial deposits.
In due time the author of the article has publicly expressed his personal opinion as to unreasonably of high scores of the lower visean -Tournaisian complex at the Solohivsk - Dikansky wall but his argument, unfortunately, was not taken into account. The basis of this argument was and remains a feature of the history of the geological development of the near-axial part of GE (from Glinsko - Rozbyshivsky wall and further east). It is the uncompensated mode of sedimentation, caused by high speed deflection bottom of the bassin and the remoteness from the wearout area of fragmented material.
It could be formed here only deepwater facies pelitic of fragmented material, so there is no reason to expect at the bottom of the upper (B -22 -23) visean and lower visean oil and gas reservoirs the conditioned complex granular type. As for the carbons as lower visean and Tournaisian, the uncompensated nature of the sedimentation mode of basin during this period also not contributed to the formation of the collector bioherm type. And therefore there is no reason to expect here the discovery of hydrocarbon reserves of industrial importance. At the same time, we note that this part of the section is characterized by significant gas saturation so called "shale gas" with the abnormally high pore pressure, which complicates the drilling process.
The reasonableness of this point of view has been confirmed with wells that openened the said complex (Semyrenkivsk field, Pokrovska area, Solohivsky field, Opishnyansky deposit). Other unsuccessful attempts to discover significant reserves at deep depths of the large deposits are determinate by undervaluated facies-lithological factors, but are associated with an average carbon (Zakhidno Khrestyshenk, Kobzivk, Shebelinsk).
Here, in our pont of view, there is another problem - a high degree of grittiness, poor sorting of fragmented material and lack of reliable caprocks, which also caused litofatsialnym factor.
Against the background of the unsuccessful search of large or even medium-sized deposits a great concern is hidden behind the dry statistics tendency to fall exploratory drilling efficiency for all parameters (dimension fields, growth stocks at 1m of exploratory drilling, the rate of discovery).
It is necessary to note that the structure of growth on hydrocarbons exploratory drilling in new fields accounts for only a small proportion and the number of fields that are opened every year and their dimensions are reduced, although the volume of exploratory drilling virtually unchanged. We think that this is an alarming signal to approach of early depletion of the resource base.
Thus, the strategy of exploration work is necessary to build taking into account structures of undiscovered (С3+ D) resources. It means that it is no necessary to digress from the search for large deposits in large anticlinal structures, characterized by oil and gas bearings on the top because the nonuniversality of thesis about the significant reserves at greater depths and the inaccuracy of this direction has proved in practice.
However, this does not mean that a certain amount of deposits category average volume stocks can be expected in areas of litofatsialnoho replacement of sandstones by clayey rocks. This fields are necessary to search at the monoclonal slopes of wall type large structures of 2-3 orders of deflections and slopes.
Mandatory for the effective implementation of this direction should be litofatsialnyy analysis and study of the conditions of sedimentation prospective of oil and gas bearing sector, and the results of this analysis should precede seismic survey. Within the northwestern sector of GE dominant complexes should be considered as Serpukhivsky and Visean. Regarding lower visean and Tournaisian complex, the most part of its potential to be correlated mainly with terrigenous and carbonate facies of near edge zones.
Paying tribute to exploration of small or medium-sized fields and critically assessing the structure of undiscovered resources, we must recognize that their main scope fits within the small and very small traps of structural form of nonakticlinal type. This shows analysis of the fund, both identified and prepared structures. Even though that their resources of class 333 and 334, is usually too high, most are no more than 2 units of fuel. Therefore, we have to remember that over time, growth stocks, significant part of which is formed by the exploration of previously discovered large or medium-sized fields will rapidly decrease, and therefore the role of exploratory drilling on new facilities should increase.
The more of the exploration prospects will be introduced annually into the exploratory drilling, the more likelihood of lifting compensation. This thesis is well known, but today it obtains the more urgent in view of the unfavorable structure increased in recent years stocks (it is the part of stocks in total, increased by new fields).
Author
Zyuzkevych Mykola Petrovych
Candidate of geol. science, Chief Geologist on the private multi-enterprise "Technics". Specialty Engineer explorers. Main directions of scientific activity - search and exploration of oil and gas, theoretical justification of prospecting drilling in some areas and deposits, analyze the effectiveness of exploratory drilling, zonal and local factors of hydrocarbons.
PETROLEUM GEOLOGY
New areas of work related to search of large deposits of
hydrocarbons in DDD
UDK 553.98 © M.I. Machuzhak
Candidate of geological-mineral sciences at Ukrgazvydobuvannia PJSC
A.V. Lyzanets
Candidate of geological-mineral sciences
A.S. Tykhomyrov
UkrNDIgaz
Based on the research of geological structure, gas content, and facies analysis of reservoir formations of Kobzivske gas condensate field a forecast was made for distribution of the lithologically screened traps to search for natural gas deposits in Lower Permian - Upper Carboniferous build-ups on the monoclinal slope s of Zhovtneva area and Hryhorivskyi depression. The recommendations for 3D seismic surveys are justified, and the forecasted gas resources of prospective targets are estimated.
Key words: Kobzivka gas field, Oktiabrska area, Hryhorivskyi depression, lhitologically screened traps, gas deposits, resources
Over the past 30 years only one large gas condensate field, Kobzivka, with initial reserves and prospective resources of gas reservoir estimated at over 40 billion m3 [1], was opened in the Dnieper-Donets basin due to exhaustion of the fund of large non-drilled anticlinal structures and a high level of initial development of oil and gas resources of the basic oil and gas-bearing complexes.
The field is unique in that it first clearly demonstrated the possible existence of lithologically screened deposits in sediments of Kartamysh strata of the Lower Permian-Upper Carboniferous in non-structural conditions. This allows defining a new direction of exploration, i.e. search for hydrocarbons in the Lower Permian – Upper Coal Complex in non-anticlinal traps in the depression areas.
Understanding the geological structure peculiarities and deposit accumulation conditions which contributed to the formation of gas deposits at Kobzivka GCM allows predicting the presence of gas deposits in similar geological conditions and identifying the new areas (territories) for exploration.
Kobzivka gas condensate field (GCF) is tectonically located in the Near-axispart of the Central Graben of the Dnieper-Donets depression (DDD) and is dedicated to roller-like raising between Oktiabrska and Kegychivsk elevations.
Kobzivka structure, judging by the reflecting horizons in the Paleozoic, is an asymmetrical pleated brahianticlinal fold of sublatitudinal stretch with the size of 18×8 km in the Lower Permian – Upper Coal Complex sediments (limestone Q8 at the bottom of Mykytivka strata). The fold is characterized by plicative nature of the structural form, and the absence of ruptures s in sediments of the underlying Lower Permian – Upper Coal Complex.
The southern wing of Kobzivka structure is immersed into Grygorivka synclinal basin, the northern wing – into the South-Sosnivka basic; it opens towards Kegychivka anticline through a narrow saddle (the amplitude of the arch from the saddle level is around 80 m) in the east, and it borders with the northern wing of Oktiabrska structure in the west (Fig. 1).
Fig. 1. Kobzivka GCM. Seismic structural map by the reflecting horizon of IV G2
Fig. 2. Kobzivka GCM. Schematic geological section along the well line 73-21-56-58-20-70.
78 wells were drilled in Kobzivka field, which confirmed the commercial gas bearing of Kartamysh strata of the Lower Permian and Upper Carboniferous between which there is a stratigraphic inconsistency, i.e. Melykhiv erosion.
Upon calculation of the field commercial reserves in the gas-bearing thickness, the productive horizons were conventionally broken down into subhorizons, in the Lower Permian sediments A-5 (Р1nk), A-6, A-7, A-8 (R1
kt) and G-6 in the sediments of the Upper Carboniferous (С3
kt). The stocks were counted for each subhorizon separately.
In fact, Kobzivka field combines two condensate deposits in fundamentally different types of traps.
The gas condensate deposit in sediments of Kartamysh strata of the Lower Permian is confined to the vault-like part of Kobzivka brahianticlinal fold (Fig. 2) and is analogous to the corresponding deposits or Permian parts of deposits of the Western Khrestyshche, Yefremivka, Melyhivka, Lannivka and all other fields of Mashivka- Shebelynka zone of large deposits of the south-eastern part of the PPD with massive stratal deposits in terrigenous sediments of Permian-Carbon well under the chemogenic cap.
The characteristic features of these deposits is the presence of a large number of low-capacity interlayers of gas-saturated sandstones and siltstones in the predominantly clay strata in the section, total or partial lithologic restriction of the reservoir development fields in the area and in the section, a conventionally single gas and water contact with the possible presence of lithologically limited interlayers with jammed waters.
The collectors in Kobzivka field are sandstones and siltstones. Sandstones are usually brown, mostly thin- and fine-grained, loamy. The fine-grained sandstone layers often contain the interlayers of sandy gravelites. Judging by the descriptions of species, conducted by UkrNDIgaz specialists, the polymictic and field spar-quartz differences are prevailing, and the olygomict sandstones are rarer. The sandstone cements are predominantly argillaceous, kaolinite-hydromicaceous, rarer carbonate-clay; their type is loop-like, incompletely porous, porous, basal porous [2, 3].
As a result of the study of reservoir properties of the reservoir rocks and facies analysis it was concluded that the rocks of Kartamysh strata of Kobzivka deposit are represented mainly by deposits of surface and underwater part of the delta formed during the movement of terrigenous material from the southern board zone of DDD. It also indicates the presence of deposits of discontinuous flows and alluvial deposits of the meandering rivers.
An absolute mark of the conventional gas and water contact of the gas condensate deposit in sediments Р1kt is -
3,382.5 m and the apical position of the foot of Mykytivka strata confirmed by drilling (limestone Q8) is 3,150 m (well 14). Thus, the total floor level of the gas content is more than 240 meters.
Fig. 3. Schematic geological section along the line II-I
The reservoir holds about a third of the initial gas reserves of С1 category of Kobzivka field.
In the western part of Kobzivka GCM there was found the largest deposit reserve, i.e. deposit of horizon G-6, confined to the combined layered lithologically-screen trap of the fairly complex configuration. The reservoir occupies the western periclinal of Kobzivka elevation and extends through the saddle to the northern slopes of Oktiabrska elevation. The G-6 horizon deposit contains four layers, the most seasoned of which by area is G-62 subhorizon. Its collector holds 95% of the initial recoverable reserves of gas deposit C3
kt. As regards the extension, the deposit is limited to lithologic screens in the arch-like part of the fold and in the west periclinal near the saddle between Kobzivka and Oktiabrska elevations (Fig. 3) and with conventional gas and water contact with an absolute mark of -3667 m at layers’ immersion in the wing parts.
The location of such a large area of hydrocarbon deposit beyond the structural trap indicates the special conditions of sediment accumulation, generation and preservation of hydrocarbons.
Fig. 4. The southeastern part of DDD. The structural map by reflecting horizon IV Г2(P1nk)
The presence of the inconsistency within Kartamysh strata (Melykhiv erosion) leads to a significant change in its total capacity up to the complete erosion of the Upper Carboniferous part of the strata (C3
kt), as evidenced by a number of wells outside the field, where the red deposits of Kartamysh strata of the Lower Permian are placed directly on the grey araucaritic strata of the Upper Carboniferous. Change of the sedimentation regimes (transgression-regression cycle) led to changes in spatial streams on the border between land and sea, and, accordingly, the position of sandstone bodies.
The coastal sea conditions were favorable for the formation of sand-alevritic alluvial, talus, deltaic sediments, which are the reservoirs containing the gas deposits. In the area of the Kobzivka structure location during the Kartamysh epoch there was the flow unloading zone directed from Oktiabrska horseback to Grygorivka deflection.
It is possible that during the correlation of sections of wells of the different fields the Permian and Carboniferous boundary within a fairly uniform cut of the Kartamysh strata is accepted by mistake and the sandstone of horizon H-
62 indexed in Kobzivka field is nothing but a basal sandstone of Permian sediments. This opinion is prompted by its consistency within the development field in view of the lithological limitations in general, better separation of grains than in the other layers, as well as the improved and sustained reservoir properties.
At the Lannivkam Western-Khrestyshche, Western-Sosnivka, and Kehychivka fields located in this zone the gas content within the anticlinal structures of sandstones are indexed differently, but are correlated satisfactorily with H-62 horizon of Kobzivka field.
Fig. 5. Kobzivka GCM. The map of distribution of the complex parameter in the range of 28 to 42 msec over the reflecting horizon Va, (С3, Kt)
However, the opening of Kobzivka deposit showed that the significant reserves of hydrocarbon deposits may not necessarily be confined to the anticlinal structures in this part of DDD. This fact opens up new perspectives and ways to search for hydrocarbon deposits.
Based on the peculiarities of the sediment accumulation at Kobzivka GCM, the genesis of reservoir rocks and taking into account the presence of the gas deposit far beyond the apical part of Kobzivka anticline, we can predict the distribution of gas reservoirs located next to the structural elements, especially in the western part of Kobzivka GCM on the northern slope of Oktiabrske elevation behind the saddle between them. GCS Ukraine justified and approved the gas reserves in the amount of 9.4 billion m3 of category C2 (code 332) within this zone.
Most likely, this zone is separated from the main deposit of H-62 horizon with a lithological circuit at Kobzivka field, as evidenced by drilling of wells 100, 30, 42, 42-bis. The availability of the lithologically-screened traps in this area may be due to sedimentation of flows transferring the terrigenous material from the west.
Based on the analysis of the results of drilling of wells 100, 30, 106 at Kobzivka GCM, the data of stratigraphic partitioning and testing of wells at Oktiabrska area, there was found no С3
И deposit at Oktiabrska area and the availability of a collector in these sediments on the slope of Oktiabrska elevation (well 106, Kobzivka), indicating the possible existence of lithological-screened traps on the slope of Oktiabrska elevation [5].
The projected growth of collectors on the slope of the southern board monoclinal can be associated with the alluvial and diluvial deposits of surface and underwater part of the delta, sediments of riptide flows and alluvial sediments of meandering rivers formed during the movement of terrigenous material from the southern board zone of DDD. So, here were the necessary conditions for the formation of lithologically-limited and lithologically-screened traps for gas accumulation in alluvial and diluvial sandy-alevritic sediments.
On the slope of Grygorivka deflection there were identified three promising area to search for hydrocarbon deposits in lithologically-screened and lithologically-limited traps (Fig. 4):
1) on the southern slope of Grygorivka deflection opposite to Kobzivka GCM. The existence of deltaic sediments as an extension of the revealed delta within Kobzivka GCM in this zone is not excluded;
2) on the southern slope of Grygorivka deflection opposite Kegychivka GCM;
3) in the eastern part of Grygorivka deflection in the area of Tymchenkivka rod.
The development of reservoir rocks of the "stain" nature is supposed within the projected zones. Judging by the rise and extension of strata, the predicted traps should have a lithologic screening, as well as lithological screening or a gas and water contact on submerged strata. The configuration of traps within the allocated prospective zones can have any shape, depending on the plane development of reservoir rocks, so their prediction requires special seismic studies.
To predict the spatial development of reservoir rocks, i.e. traps for gas accumulation, it is recommended to conduct the seismic 3D works subject to construction of thin-layered models of reservoir rocks porosity and development within the promising areas. An example of the successful application of this technique is Kobzivka GCM, where UKRNAFTA-gazgeofizyka CJSC conducted 3D seismic works in 2006. The cards of porosity, sandiness, complex parameter etc., built according to the productive part of the cut in sections every 28 m (14 ms), were the basis for the selection of places to lay the new exploration wells. The results of drilling wells generally confirmed the forecast of reservoir rocks development. For example, the map of distribution of the complex parameter for 28-42 ms interval over Va1 reflecting horizon in the foot of С3
kt sediments, corresponding to the interval of occurrence of the main productive horizon H-62, highlights the areas of reservoir distribution in the western periclinal of Kobzivka fold and the zones of deterioration of reservoir properties in the apical part of the structure, as well as in the saddle between Kobzivka and Oktabrska elevations (Fig. 5). The drilling results confirmed such distribution of reservoir rocks.
The successful use of 3D seismic work materials at Kobzivka GCM indicates that this technique is promising and needs to be used for the prediction of collector rocks distribution and contour determination of the predictive lithologic traps.
The area of the southern monoclinal slope of Grygorivka deflection has the significant projected reserves and resources of gas calculated by the density of gas reserves of category C1 on H-62 horizon in Kobzivka GCF as 295 million m3 per 1 km2 of area.
The gas resources in four projected areas on the southern monoclinal slope of Grygorivka deflection, based on their size and density of the adopted inventories, represent over 180 billion m3 of gas. It is clear that the entire area of the allocated promising zones will not be gas bearing. This is only a zone within which it is possible to open separate hydrocarbon deposits.
List of References
1. Benko V.M. Kobzivka GCM - the main object of exploration works, gas production expansion and increase of resources of Ukrgazvydobuvannia SE / V.M. Benko, V.V. Dyachuk, M.I. Machuzhak [et al.] // Problems of Ukraine's gas industry development: Collection of scientific papers. - 2007. - Vol. XXXV. - P. 7-13.
2. Lahutyn A.A. Lithology and capacitative fitration properties of alevritic-sand rocks of Kartamysh strara of Kobzivka deposit based on the core studies / A.A. Lagutyn, S.F. Poverennyi, V.N. Buhtatyi, O.Y. Stepanov // Problems of Ukraine's gas industry development: Collection of scientific papers. - 2007. - Vol. XXXV. - P. 13-18.
3. Kryvulia S.V. Structure and facial features of lithologically-screened deposit of productive horizon H-62 of Kobzivka gas condensate field / S.V. Kryvulia, A.A. Lahutin, A.V. Zahorodnov [et al.] // Exploration and development of oil and gas fields. - 2012. – No. 3 (44). - P. 135-144.
4. Stratigraphy of USSR / T.Y. Lapchyk. - K.: Scientific opinion, 1970. - 246 p. - Vol. VI. - Part 1.
5. Kryvulia S.V. Lithologically-screened and structural-tectonic traps in P1-C3 deposits in the Central Graben and southern board zone of the southeastern PPD / S.V. Kryvulia, A.A. Lagutin, O.S. Minosyan [et al.] // Bulletin of Karazin National University of Kharkiv. - 2012. – No. 997. - P. 44-50.
Article Authors
Machuzhak Mykhaylo Ivanovych
Candidate of Geological and Mineralogical Sciences, the chief geologist of Ukrgazvydobuvannia PJSC. He graduated from the Ivano-Frankivsk Oil and Gas Institute. His research interests cover the geology, prospecting, exploration and development of oil and gas deposits.
Lyzanets Arkadiy Vasyliovych
Candidate of Geological and Mineralogical Sciences, Deputy Director for Geology of the Ukrainian Scientific-Research Institute of Natural Gases. He graduated from the Ivano-Frankivsk Oil and Gas Institute. His research interests cover the geology, prospecting, exploration and development of oil and gas
eposits. d
Tykhomirov Andriy Sergiyovych
Researcher of the Ukrainian Scientific-Research Institute of Natural Gases (UkrNDIgaz). He graduated from Karazin National University of Kharkiv. His research interests cover the geology, prospecting and exploration of oil and gas deposits.
PETROLEUM GEOLOGY
On the issue of the Black Sea methane hydrate potential development
UDK (553.981:548.562): 620.91] (100)
© O.A. Kychka, A.M. Koval Candidate of geological sciences
A.P. Tyshchenko Candidate of geological sciences
T.E. Dovzhok Candidate of geological and mineral sciences
E.E. Korovnichenko Naukanaftogaz SE of Naftogaz of Ukraine National Joint Stock Company
First successful pilot test to produce methane from submarine gas hydrate field in the East Nankai trough offshore Japan has resumed practical interest to develop giant methane hydrate potential of the World Ocean and the Black Sea basin as well. The paper features geological aspects and technological problems of submarine gas hydrates exploitation and discuss methane-hydrate potential assessment and promising exploration prospects in the Ukrainian part of the basin. The recommendations to methane hydrates development in the Black Sea are given.
Key words: gas hydrate, methane production, World Ocean, Black Sea, recourses, subsea deposits
The methane hydrates of the World Ocean, due to their huge geological resources, may become one of the sources for provision of the constantly growing energy needs of the mankind in the near future. The theory of their formation and existence under certain thermodynamic conditions is rather well developed [1, 2]. Today, however, a number of geological, technological and environmental problems require the scientific study and practical solution, in order to allow the industrial and environmentally sound extraction of gas hydrates.
Apart from the concurrent operation of methane hydrate caps together with free gas on giant fields of Messoyaha and Prudhoe Bay, the practical start of extraction of the proper gas hydrates should be considered the hydrate deposit extraction using a thermal cyclic test method in Mallic well in the Mackenzie Delta in the Canadian part of the Buford Sea basin in 2002. Later on, in the Arctic slope of Alaska the research trials of Mount Elbert well in 2007 and 1-Ihnik Sikumi in 2012 was conducted, which tested the possibility of combined gas hydrate extraction via injection of carbon dioxide in the hydrate-bearing collector and methane replacement while reducing the pressure during pumping off of the formation water, then the gas hydrate was decomposed, and the released methane was fed into the well. The pressure and flow rate was measured at its estuary, the gas composition was analyzed, and the gas was burned in a flare. The methane hydrate facility is represented here by three horizons of fine-grained turbidite sands of Pleistocene Osaga formation with intergranular porosity 42-45% (the hydrate cements the rock and covers 80% of the pore space), so it is no surprise that the research well began excreting the sand intensively and form the tubes, due to which the extraction had to be stopped. The overall hydrate reservoir layers occupy up to 20% in the sand-clay section of the front part of the underwater cone of the said formation [4]. The hydrate deposits lie at the depths of 290 to 300 m from the ocean bed and are characterized by double seismic horizon BSR (bottom simulating refector).
Fig. 1. Location of research and production wells (red star); the methane hydrate deposits nearby the coast of Japan are shown in blue
Fig. 2. The gas and hydrate bearing layers in Osaga Pleistocene formation disclosed be parametric wells [3]
The Black Sea is characterized by the highest methane degassing vs. the other seas [1] and is one of the world's most promising basins for methane hydrates extraction. As you know, this is where the first methane hydrates were documented on the seabed. The experts of all Black Sea countries, i.e. Ukraine, Bulgaria, Turkey, Romania, Russia and Georgia, as well as international research groups [5, 6] study the hydrate capacity of the Black Sea. Recently a technology of the so-called "autoclave drilling" and sampling to a depth of 100 m from the seabed to explore the hydrate bearing layer was performed here [7]. However, the unresolved technological issues and a factor of the extremely environmentally sensitive semi-closed system of the Black Sea postpone the start of the practical work on development of its methane hydrate potential.
The recent decades the study of gas hydrates of the World Ocean showed that the gas hydrate layer at the depths of the sea, where there are favorable conditions for its existence, is not powerful and sometimes even not continuous, so the resource base of gas hydrates is adjusted continuously according to the new data. It is certain that the local zones of methane hydrates cover the edge fractured zones of offshore sedimentary basins, intercepting the powerful upward flow of the deep thermogenic methane and form a multilayered cap for sub-hydrate gas reserves in terrigenous reservoirs. The latter is somewhere broken with recent tectonic movements and mud volcanic processes.
In the most submerged part, where the tectonic faults are few, the gas hydrates contain mainly themicrobial methane of biogenic origin.
Due to the hydrate saturated soil sampling during research visits, seismic, seismic acoustic and geochemical surveys in the Black Sea several strong fields (deposits) of underwater methane hydrates representing the practical interest were mapped [1, 5, 8, 9]. The assessment of their geological resources in the Ukrainian sector of the Black Sea differs significantly, from 15 to 60 trillion m3 in terms of methane, reflecting various methodological approaches of various researchers to the calculation of stocks of these yet poorly investigated raw materials, so this problem needs the further in-depth research.
The depths of the Black Sea show the following gas zoning: beyond the edge of the continental slope there is a circum-Black Sea area of off-hydrate through gas transit and a gas cluster invasion/migration zone in the bottom sediments (so-called chimneys) nourishing the submarine gas geysers (gas seeps) and is traced to the depth of approximately 750 m [10]; further in depth there is an area of the island hydrate saturation followed by the area of complete hydrate bearing (with powerful multilayered deposits in terrigenous reservoirs at fault paths of the upward gas migration and BSR proliferation) in the area of submarine slope and continental foot of the Black Sea. Finally, the deep central part is occupied by an almost unexplored area of low-capacity coating hydrate saturation in clay-mud basin sediments where the schlieren and embedded manifestations of methane hydrate do not form a continuous layer, so the BSR is not observed.
Fig. 3. The location of JOGMEG production well on the slope of the ocean cove. The arrows trace the double BSR [3]
Fig. 4. Zone of underwater gas manifestations (red dots), the upper edge of gas hydrates distribution according to the simulation data (dotted line and arrow, white), gas hydrate deposits (green) in the Western Black Sea Basin [9]
Concerning the BSR seismic boundary, which is an indicator of selection of the gas hydrate thicknesses, it is worth noting the following. In 1970 the existence of an appropriate seismic reflective boundary in several environments rich in gas hydrates was revealed. Its position coincided with the thermodynamically determined depth of the gas hydrate stability zone (GHSZ) foot. These new results are widely used in the seismic data for massive gas hydrate deposits. The aforesaid reflecting boundary can be easily recognized because it is parallel to the sea bed and has a reverse polarity. BSR usually crosses the stratigraphic horizons on seismic profiles since its position is determined rather by difference of acoustic impedances between sediments saturated with gas hydrates (above the BSR, in the GHSZ area) and gas-saturated sediments beneath.
Yet BSR is not always evident or observed in seismic profiles located in the rich gas hydrate environments. For example, the gas hydrates have been found in some cases without a BSR. This suggests that other parameters such as the distribution of gas hydrates in the GHSZ stability zone, the total number and structure of gas hydrates, gas distribution below GHSZ etc. affect the BSR development. In some places with the well-marked BSR on seismic sections the small number hydrate samples was collected from the core [11]. Thus, BSR as an indirect proof of the gas hydrate availability can be used only as one of the criteria for selection of gas hydrate thickness in combination with the other direct and circumstantial evidence.
There are many examples of BSR allocation within the zone of continuous hydrate capacity of the Black Sea. Subject to its presence in the western part of the Black Sea, the Romanian researchers [9] clearly distinguish 4 projected hydrate bearing areas (Fig. 4).
Using these data, we explored the relevant anomalies on the materials of the regional 2D seismic investigation obtained by MSGT. As a result of processing of the data across multiple seismic profiles the BSR was traced (Fig. 5), and it was attempted to identify the projected methane hydrate deposit (Fig. 6).
Fig. 5. BSR tracing on BS-05-26 seismic profile (deep cut)
Fig. 6. Example of methane hydrate deposit allocation on the continental slope of the northwestern part of the Black Sea (seismic profile BS-05-26, time section)
Solving the problem of mapping the potentially gas hydrate-bearing facilities on the basis of 2D seismic materials require the use of the specialized dynamic data processing in order to learn more about the features of the geological environment. Solving the appropriate task required the implementation of all processing procedures in the mode of saving of the "true amplitudes" of seismic waves for the entire time period of registration. The "true amplitudes" are the amplitudes which suffered the minimal distortion of the dynamic characteristics of the seismic record while processing. The resulting seismic section a priori should reflect an adequate distribution of reflection coefficients both in literal and in the direction of increasing the time of registration.
To systematize the application of a sequence of procedures and determination of the values of their parameters the seismic data processing graph consisting of 6 blocks was developed.
Block 1. Formation of the geometry of observations subject to inclusion of information in the headers of the input seismograms and obtaining of a priori temporal section of the common midpoint.
Block 2. Weakening of various types of interferences, noise and short-wave reverberations on the input seismograms sorted by general arousal items.
Block 3. Reduction of the impact of low-rate interference waves.
Block 4. The correction of a seismic signal according to the slope of the reflecting boundary and entering of the adjustment for the wave arrival time, adjustment of summation velocity, formation of the final time cut, increase of the resolution and signal/noise ratio at the time of the final cut.
Block 5. Obtaining of the migrated image in the time scale.
Block 6. Obtaining of the migrated image in the depth scale.
As a result of such processing in combination with the use of modern methods of parameter transformations on the experimental test site, we managed to:
detect the wave field anomalies, which spatially correspond to the projected gas hydrate-bearing facility;
identify the peculiarities of the gas hydrate-bearing boundaries determination;
establish the seismic parameters of the gas hydrate-bearing facility allocation.
During the processing, the focus was on maintenance of dynamic properties of the seismic record and obtaining of the wave field with high resolution, especially in the upper (pallet) range of the section part with favorable conditions for the methane hydrate formation. The time and depth seismic sections obtained in this way provide additional information about the structure of the upper (pallet) section part, help determining the morphology of predictive gas hydrate-bearing facilities and estimating their resources during the first approximation.
Based on the above, in view of some progress in predicting the gas hydrate deposits within the Black Sea and given the success of the experimental extraction of methane from ocean gas hydrates of the Eastern-Nankay ocean cove, we can speak about the reasons for the planning of relevant works in terms of the Ukrainian sector of the Black Sea waters.
The further practical steps in the development of methane hydrate resources in the Ukrainian sector of the Black Sea require the geological and economic evaluation of the implementation of resource potential based on the knowledge of their properties, spatial localization and geological resources in the underwater depths, practicing the environmentally friendly manufacturing processes of industrial production and the adjustment of the relevant legislation on subsoil management. These steps should create the required economic attractiveness for investors interested in frequent resources utilized in methane hydrate deposits, in order to accelerate their market development with the appropriate government regulation of this process.
We believe that Ukraine should rethink the fact that the development of gas hydrate resources is one of the promising areas in the state policy of resource provision and priority directions of development of domestic oil and gas industry. Accordingly, in the first place, it is necessary to amend the legislation governing the subsoil management and oil and gas extraction in Ukraine, including the Code of Ukraine on Subsoil, Tax Code, the Law of Ukraine on Oil and Gas, the Law of Ukraine on Alternative Energy, the Law of Ukraine on Licensing Certain Types of Activities and other laws and regulations in order to settle the legal framework of gas extraction from gas hydrates in Ukraine.
Second, it is required to develop and adopt the national target program for development of methane hydrate resources of the Ukrainian sector of the Black Sea up to 2030. The relevant concept and the program should be developed for the state budget funds.
Such target programs [12] exist in five countries, i.e. the U.S., India, Japan, Korea and China. In the four former countries these are the third programs in sequence and in China it is the first. Japan, which has moved ahead of the others in extraction of gas hydrates in marine conditions has invested more than USD 800 million its hydrate program, China – USD 200 mio, Korea – USD 132.5 mio, India – USD 85 mio, and U.S. - 58 mio. The experience and results of work of the relevant countries should serve as certain guidance for our country in planning of the works related to development of gas hydrates in the Ukrainian sector of the Black Sea.
In the course of development and implementation of the state target program it is appropriate to conduct the fundamental and applied research, which should include the works for:
determination of the conditions of formation, the characteristics of spatial localization and isotopic fractionation of methane hydrate deposits;
geological and economic evaluation of development of the methane hydrate resource potential;
determination of the optimal set of geological prospecting (seismic, seismo-acoustic, electromagnetic, geochemical, drilling, geophysical borehole investigations, geological and industrial, etc.) for prospecting and exploration of deposits and evaluation of methane hydrate reserves in the Black Sea;
determination of technologies for optimal drilling test operations to disclose and extract the methane hydrates in the Black Sea.
At the early stages of the gas hydrate resources development special attention should be paid to the search for deposits of the sub-hydrated gas in terrigenous reservoirs of the bottom arch structures and non-structural traps and study of their gas hydrate cap during exploration, and the work program to be performed under special permits for subsoil management and agreements on distribution of products for all contractors of geological exploration works in deep water of the Black Sea should provide for the obligation to examine the potential hydrate-bearing layer.
Another important task which must be addressed in Ukraine in connection with this problem is the purchase of the modern drilling platform with the ability to drill at a depth of more than 700 m and a better launching of construction of the platform for deep-water drilling at the shipbuilding enterprises of Ukraine, as a global demand for such platforms and vessels is growing.
List of References
1.Shnyukov E.F. Methane gas hydrates in the Black sea / E.F. Shnyukov // Geology and minerals of the World Ocean. - 2005. – No. 2. - P. 41-52. 2.Makogon Y.F. Gas hydrates. History of study and development prospects / Y.F. Makogon // Geology and minerals of the World Ocean. - 2010. – No. 2. - C. 5-21. 3.Fujii T. et al. Resource Assessment of Methane Hydrate in the Eastern Nankai Trough, Japan // Offshore Technology Conference, 5-8 May 2008, Houston, Texas, USA. - 2008. - 15 p. 4. Egawa K. et al. Three-dimensional paleomorphologic reconstruction and turbidite distribution prediction revealing a Pleistocene confined basin system in the northeast Nankai Trough area // AAPG Bulletin. - 2013. - No. 5. - P. 781-798. 5. Vasilev A. First Bulgarian Gas Hydrates: Assessment from Probable BSRs // Geology and minerals of the World Ocean. -
2010. - № 2. - C. 22-26. 6. Bohrmann G. et al. Origin and distribution of methane and methane hydrates in the Black Sea. Meteor R / V Cruise No. 84, Leg 2, February 26 - April 02, 2011 // METEOR-Berichte, 2012. - 61 p. 7. Heeschen K.U. et al. Quantifying in-situ gas hydrates at active seep sites in the eastern Black Sea using pressure coring technique // Biogeosciences. - 2011. - No. 8. - P. 3555-3565. 8. Sokurov O.N. Global experience of approach to addressing of the issue of gas hydrate as a source of the energy raw materials / AN Sokurov // Collection of scientific works of the Institute of Geological Sciences of Ukraine. - 2010. - Vol. 3. - P. 342-349. 9. Popescu I. et al. Seismic expression of gas and gas hydrates across the western Black Sea // Geo-Marine Letters, 2007, vol. 27 Issue 2-4. - P. 173-183. 10. Naudts L. et al. Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea // Marine Geology 227, 2006. - P. 177-199. 11. Holbrook, W.S. Seismic studies of the Blake Ridge: Implications for Hydrate distribution, methane expulsion, and free gas dynamics, in Paull, CK, and Dillon, WP (Eds.) Natural Gas Hydrates: Occurrence, Distribution, and Detection Geophysical Monograph, American Geophysical Union (Publ.) 124 2001. - R. 235-256. 12. Makogon Y.F. Gas Hydrates the Black Sea / Makogon Y.F. // Files of the 11th International scientific-practical conference Oil and Gas of Ukraine – 2013, Yaremche, September 4-6, 2013 - Lviv: Centre of Europe, 2013. - P. 174-175.
Article Authors
Kychka Oleksandr Anatoliyovych
Head of Unit for Combination of Oil and Gas Search Methods of the Department for Supervision and Information Support of the Seismic Exploration Works of the Center of Seismic Research and Combination of Oil and Gas Search Methods of Naukanaftogaz SE, AAPG Authorized Representative in Ukraine. Specialist in petroleum geology, oil and gas genesis, regional tectonics as well as oil and gas research technologies.
Koval Anatoliy Mykolayovych
Ph.D. in geological sciences, senior researcher, Head of the Department for Supervision and Information Support of the Seismic Exploration Works of the Center of Seismic Research and Combination of Oil and Gas Search Methods of Naukanaftogaz SE. Specialist in petroleum geology as well as oil and gas research technologies.
Tyshchenko Andriy Pavlovych
Candidate of geological sciences, Head of the Department for Processing of Seismic Data of the Center of Seismic Research and Combination of Oil and Gas Search Methods of Naukanaftogaz SE. Specialist in geophysical methods in oil and gas geology, processing and interpretation of the seismic exploration data.
Dovzhok Tetiana Yevgenivna
Candidate of Geological and Mineralogical Sciences, the First Deputy Director for Research, a full member of UOGA, laureate of the State Prize of Ukraine in Science and Technology. Specialist in petroleum geology.
Korovnichenko Evgen Yevgenovych
Head of the Center of Seismic Research and Combination of Oil and Gas Search Methods of Naukanaftogaz SE, geologist-geophysicist. Specialist in geophysical methods in the oil and gas geology.
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GAS AND OIL EXTRACTION
Effectiveness of the Powerful Methods of Oil and Gas Production Intensification and Prospects of Their Application for
Unconventional Collectors
UDK 622. 245. 3. 5: 622. 276. 66
© Y.I.Voytenko
Dr. of technical sciences of UkrDGRI
Analyzed of world experience using modern technologies explosive intensification of oil gas output, pulse and stationary hydraulic fracturing. The prospects of using pulsed counterparts of hydraulic fracturing to extraction unconventional resources is shown.
Key words: explosive technologies, stimulation, oil, gas, fracturing, unconventional resources
The efficiency of oil and gas extraction is inextricably linked to the development and application of the advanced methods of intensification of reservoir fluids inflow. Recently, this problem has become even more urgent in view of the necessity of involvement of unconventional oil and gas reservoirs in the development. All progress in the course of development of the gas shale rock deposits in the U.S. and other gas pools in the world is associated with the use of one of the methods of oil and gas extraction intensification, i.e. layer hydraulic fracturing (LHF) in horizontal wells (HW). The main factor hindering the global spread of this technology is the need to use the large amounts of water mixed with chemical additives posing a danger to the environment and groundwater.
While the main concern of conventional collectors is preservation of reservoir properties (pore and fracture permeability) during the primary and secondary disclosure, fluid permeability restoration in the damaged contaminated zone around the well after the initial disclosure, for unconventional (dense, gas shale rock) deposits it is the increase of the collector fluid permeability by establishing the new drainage channels, i.e. macro or micro cracks [1-5]. The purpose of this paper is to analyze the efficiency of the powerful advanced technology for intensification of oil and gas extraction capable of competing with LHF and to evaluate the possibility of their use for gas production from unconventional reservoirs.
This article examines the physical and combined methods of the oil and gas extraction intensification, including:
new methods of layer torpedoing;
pulse layer fracturing with a powder charge, generator drills, or fuel and oxidizing mixtures (FIM);
explosive and chemical methods (explosion or combustion in the environments of chemically and physically active fluids which filled the vertically or obliquely-directed well).
It should be noted that the experts in hydraulic fracturing find the layer fracturing to be the best of all current technologies of the oil and gas extraction intensification [6-8]. Indeed, the LHF cracks not only have the largest size (~ 20-200 m) [6, 9], but are also maintained in the open position with propant agent, which is injected into the crack developed in the reservoir together with the fluid. The LHF cracks permeability exceeds the reservoir permeability by several orders. The ratio of the reservoir fluid consumption through a crack q(25) 25 wide vs. the consumption through a porous layer q(k, h) is determined by the formula q(25)/q(k,h) =(28)3/12kh, where k is the permeability of the reservoir, and h is layer thickness. In the case the crack N is q(2δ)/q(k,h)=N(28)3/12kh. Simple calculations show that the fluid consumption through a crack, for example 0.5mm wide, will be 8,333 times greater than for the layer with a capacity of 1m and permeability of 10-2 mcm2.
During the past 40 to 60 years the advanced technological countries of the world developed the pulse analogues of LHF and blasting methods for intensification of oil and gas extraction. The first group includes the solid fuel thermal processing technology with the slowly burning charges or liquid combustive-oxidizing mixtures. The second includes the different methods of the layer pulse hydraulic fracturing using the fast burning modern powder pressure generators, POS, perforator generators, and modern methods of layers torpedoing. The technology represented by this group of methods is characterized by higher pressures, which are usually higher than the threshold pressures of hydraulic fracturing, shorter load pulses and can form from one to several cracks in the layer [1-4].
The effectiveness of explosive intensification methods of oil and gas extraction was studied based on the results of torpedoing and pulse breaks of oil, oil and gas, gas and injection wells of Ukrnafta PJSC, Ukrgazvydobuvannia PJSC, some mining companies in Russia, USA, China, Kazakhstan, and Vietnam [1-4 ]. The research results are presented in table containing the data to compare the efficiency of productive strata fracturing in wells of UkrNafta PJSC, U.S. and USSR [6-8]. The table adopted the following legend: E is pecific energy transmitted into the formation during combustion or explosion; kп are the voids of the reservoir rock.
The data analysis shows that the powerful LHF is not the most effective method of intensification of oil and gas production. Its successful competitor is the pulse layer fracturing (PLF) using GOS and its less powerful types, i.e. special techniques of torpedoing, gap formation by pressure generators, perforator generators. We believe that the residual crack opening with PLF and reservoir rock is ensured not only high pressure and deformation of crack walls, but also by the partial burnout of organics in the reservoir rock and reservoir fluid (oil or condensate) in case of a positive oxygen balance of the combustion products, thermal destruction of the reservoir rock on the crack walls and influence of the atomic hydrogen on the rock, but also by the high layer energy [2]. Besides, the table data analysis shows that:
the efficiency of the blasting methods is increased with increase of the specific energy E transferred to the layer during the device explosive effect (torpedo, pressure generator, POS charge, etc.);
the average efficiency of the most powerful pulse method of the layer fracturing is one and a half to two times higher than that of the other pulse technologies.
The maximum pressure developed during the POS, powder charges and rocket fuels combustion in pressure generators, perforator generators, and during detonation of charges in the dashboards is usually greater than the pressure which can be implemented by the modern PLF technology. This is especially true for large depths (H>4000 m). The crack size is determined by the total energy of the charge and the time of the overpressure effect of the combustion products or wave processes, not to mention the economic component of application of the methods for intensification of oil and gas production. While the share of work for intensification of oil and gas flow fir conventional collectors is ~ 0.1-1%, for unconventional collectors it reaches 25% of the total cost of works [5]. Meanwhile the cost of the PLF work exceeds the cost of its pulse counterparts by an order.
The environmental comparative analysis of PLF technology and its pulse counterparts is also disadvantageous for PLF. The first case requires the large volumes of water with chemicals, and the second provides for the products of combustion and explosion, which consist mainly of oxides of nitrogen, carbon, water and atomic hydrogen. However, we need to answer the basic question, is it possible to use the PLF pulse counterparts to intensify the gas production from unconventional reservoirs? The main problem during the break of an unconventional reservoir is to maintain the crack edges in the open state or retain the residual crack opening chemically. The increased permeability of the tight sandstone with a filtration combustion and diffusion of atomic hydrogen requires the additional study and experimental verification in vivo.
Table
Summary data on the effectiveness of explosives and pulse technology in production and injection wells
Method description Magnification of discharge by oil, Min-max (average)
Magnification of discharge by gas, Min-max (average)
Reception increase
E, MJ/m kn% Collector rocks
Dilatation layer torpedoing 1, 8 -374 (1, 8 -3 )
1.5-16 (2-7)
3, 2 -7 7 6-20 5-25 Terrigenous,carbonate (low-, medium-permeable)
Powder layer fracturing 1.5-∞ (2-3) - - 8-40 9-25 - "-
Processing with complex devices (perforator generators)
0 - ∞(3) - - 8-10 3-26 - "-
Pulse layer fracturing with POS 1,25 - ∞ (3-5)
0 - ∞ (3-8) - 50-85 4-25 - "-
Powerful PLS 1.5-∞ (3-5)
0 - ∞ 5-10 - - - "-
Not a bad illustration of the possibilities of pulse techniques in reservoirs with the properties close to the dense is the result of intensification of oil production with POS charges at deposits in Lithuania, which obtained the 1.25 to 3.9 times increased debit of wells. The reservoir layer, i.e. the medium Cambrian deposits, is represented by the strongly compacted quartz sandstone with the porosity of 4.1 to 10.2% [1]. The powder generators and POS charges are recommended by developers for collectors with clay content <30% [1]. It goes about the conventional collectors, usually with a rather high formation pressure. Some positive results have been obtained in the reservoirs composed of dense clay with AVPT zones [1].
The main types of unconventional reservoirs are tight sandstones, shales, coal layers and surrounding rock. According to [10], these are dense alevritic-sand collectors of the central basin type of the black shale formation of Sribne DDD depression, lower coal black shale deposits in the northern outskirts of Donbass and in the eastern segment of the northern edge of DDD etc. Each facility requires an individual approach taking into account the physical and mechanical properties of rocks, layer energy, as well as selection of equipment and technology.
Due to the issue of oil and gas capacity of the great depths there is an issue of low-porous sand collectors condition expansion and intensification of oil and gas reservoirs at depths exceeding 4,500 m. The analysis of the results of dozens of completed wells in DDD fields shows that at depths of 3,100 to 5,580 m the best drills, including the charges of foreign production for deep penetration are often ineffective, and they formulate the conclusion as follows, "Poor allocation of water, condensate or natural gas", "Impervious collector" or "dry." In fact, at depths exceeding 5 km the granular oil and gas collector in the traditional sense becomes a tight collector. In the absence of well-developed fractures in the productive interval it is hard to obtain the cost-effective productivity of wells even by applying the advanced disclosure technology, i.e. drilling during the depression, use of the superdeep perforation etc.
For these reservoirs and depths the special techniques and PLF technology or pulse counterparts should be used, as well as the latest disclosure technology and their design methods which would enable to determine the size of cracks fracturing or pulse division, their orientation in space, which depends on the distribution of the principal components of the rock pressure, the number of PRI cracks, their fluid permeability in the presence or absence of propant therein etc.
Thus, the article shows that the effectiveness of pulse layer fracturing techniques with conventional collectors, especially high-energy, is no worse than the effectiveness of a powerful PLF, and has all the prerequisites to address the intensification of oil and gas production from unconventional reservoirs of individual types by adapting the known pulse technologies to these new objects, particularly at great depths.
List of References
1. Dudayev S.A. Gas dynamic method of affecting the by-well area of layers to increase their oil output / S.A. Dudayev, V.I. Pavlov // Karotazhnyk. - 2010. – No. 1. - P. 15-45.
2. Shcherbyna K.G. Chemical and physical basis of the high-temperature impact on the well bottom zone with water reacting composites: abstract of the thesis ... Doctor of technical sciences / Shcherbyna Karina Grygorivna, Ukrainian Oil and Gas Institute OJSC. - K., 1999. - 34 p.
3. Mykhalyuk A.V. Protection of casing strings during the explosive works in wells / A.V. Mykhalyuk, N.A.
Lysyuk. - K.: Vipol CJSC, 2009. - 279 p.
4. Voytenko Y.I. Explosive and impulse methods for intensification of oil and gas extraction / Y.I. Voytenko, V.D. Kukshinov, I.V. Lobanov, A. Drachuk // Karotazhnyk. - 2005. - Vol. 3-4 (130-131). - P. 68-80.
5. Axelrod S.A. Gas extraction from clay shale (based on the foreign printed articles) // Karotazhnyk. - 2011. - Vol. 1 (199). - P. 80-110.
6. Gadiyev S.M. Impact on the bottomhole zone of oil wells / S.M. Gadiyev, I.S. Lazarevich. - Moscow: Nedra, 1966. - 180 p.
7. Kachmar Y.D. The use of powerful hydraulic fracturing in the fields of Ukraine / Y.D. Kachmar, A.B. Merkuryev, F.M. Burmych, V.M. Savka // Oil and gas industry. - 1999. - № 4. - P. 28.
8. Kachmar Y.D. Methods of designing the hydraulic layer fracturing / Y.D. Kachmar, V.V. Tsiomko // Oil and gas industry. - 2005. - № 4. - P. 12-15.
9. Krasnikov S.Y. Analysis of results of testing of the method of hydrodynamic stratification of the main hard-to-break rood in terms of the mine // Interaction of mechanized timbers with lateral rocks. - Novosibirsk: USSR Academy YHD CO, 1987. - Vol. 45. - P. 53-61.
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Article Author
Voytenko Yuriy Ivanovych
Doctor of technical sciences, engineer researcher. Main directions of scientific activity - technology and engineering of the secondary disclosure of productive horizons, oil and gas extraction intensification technology, rock and geological material breaking.
TRANSPORTATION AND STORAGE OF OIL AND GAS
Diffusion of Gases in Porous Environments, Taking into Account the Convective Component
UDCK 519.6:539.3
© Y.D. Pyanylo
Doctor of technical sciences
P.G. Vavrychuk
Center for Mathematical Modeling of Pidstrygach Institute for Applied Problems of Mechanics and Mathematics of the NAS Ukraine
In this work we study the process of replacing gas in porous media considering convective motion of one of the gases and dependence of diffusion coefficients on the pressure in them. We have given the formulas to calculate the diffusion coefficients, which depend on the coefficients of interdiffusion of gases and pressure. The numerical experiment shows that the convective component has a significant impact on the process of mixing gases. Key words: gas replacing, porous media, diffusion convective component
There are little papers dedicated to the investigation of a multi-component gas in porous environment, which is primarily explained by the specificity and complexity of the tasks. Modeling these processes usually leads to the need for solving the nonlinear differential equations in partial derivatives or their systems with variable, in particular discontinuous, ratios under conditions of substantial uncertainty. The movement of a two-component gas mixed in a porous environment is a typical convection-diffusion process. During the gas movement in a porous process the convective component is an order higher than the diffuse one. Upon small convective velocity and in view of the gas mixing process the process of convection-diffusion must be considered simultaneously.
The diffusion of two gases without convective component is explained by the differential equation
(1)
for given boundary conditions, where the D parameter means the coefficient of mutual diffusion of A and B gases. Many formulas are developed for its determination, including [1]
where p, T is the pressure and temperature in the system, mA and mB – are the gas masses, sA and sB are the parameters of the Lennard-Jones potential.
Indian mathematicians, Saxena M. and Saxena S. proposed the following modified formula of Sazerland for the computation of the mutual diffusion of DAB gases (с m 2/ с) [1]:
where VA, VB, TA and TB are the critical volumes (cm3/mol) and temperature (K) of gases, p is the pressure in atmospheres, TA,B=(TA TB)0,5. For nonpolar gases A=0.022023 and B=1.1756, while for systems consisting of a combination of polar and nonpolar gases A=0.022023 and B=1.90116. If the self-diffusion coefficients of DAA and DBB gases are known, then
Let’s consider a cylindrical source of gas injection, uniformly distributed along the axis. The area of the PSG reservoir is modeled with a cylinder divided by cylindrical surfaces into appropriate sub-areas filled with different gases and their mixture (Fig. 1): zone I is filled with the extracted gas, zone II occurs as a result of the displacement of the existing gas with a pumped gas, resulting in the jamming of a part of the pores, and area III is filled with injected gas. Then the equation for determination of the distribution of gas pressure in each subzone will look as follows [2,3]
(2)
where r is the radius vector drawn from the well center according to Leybenzon:
with υ = 0.002 m/s
Here p0 and p2 are the initial value of the pressure and the pressure at the area boundary respectively. The solution of equation (2) with constant boundary conditions is given in [2-4].
Fig. 1. PSG layer area distribution
Fig. 2. The dependence of the diffusion coefficient cz from time t at the distance of r= 32 m
If the pressure distribution is known, the velocity of the gas movement is determined as follows:
(3)
Here μ is the absolute viscosity of gas, and k is the permeability of the layer occupied with gas. Equation (1) takes place in the second zone only if its boundary is not shifted. Otherwise, you must consider the velocity of the boundary movement. During the displacement of one gas with another the diffusion process should be considered, taking into account the convective component, i.e. the velocity of the first zone movement. Then the problem is reduced to solution of the diffusion equation with the convective component
under appropriate boundary conditions. Here υ is the velocity of the gas in the first zone determined with formula (3). For numerical analysis of the influence of the convective component on the diffusion process a simpler model is considered, namely the gas diffusion in the layer with l thickness, described by the equation
(4)
under appropriate boundary conditions recorded as c1(r) =c(r, 0), c2(r) =c(r,l) c3(t) =c(0, t).
For consistency of conditions it is required to satisfy the equality of c1(0) =c3(0).
Solution of equation (4) will be searched using the Laplace transformation. For constant coefficients equation (4) will look as follows:
(5)
Here b= Υ /D, p1= S /D, c11=c(r, 0) /D. We assume that the b and p1 parameters are constant. The general solution of a homogeneous equation will look as follows:
where
A partial solution of the differential equation (5) depends on its right side, in particular, the method of constants variation leads to relation:
If c11 function is identically constant, then the partial solution will be cch = - cn / XlX2. At sustainable boundary conditions the general solution of the problem will be as follows
The last equality it is marked as
Fig. 3. The dependence of the diffusion coefficient cz on distance for time t = 400s and different values of the convective velocity υ ={0.004; 0.003; 0.002} m/s, where curve 1 represents the velocity of υ = 0.004 m/s, curve 2 υ = 0.003 m/s, and curve 3 υ = 0.002 m/s
Fig. 4. The dependence of the diffusion coefficient cz on distance for time t= 400s and different values of the convective velocity υ = {0.001; 0.0005; 0} m/s, where curve 1 represents the velocity of υ = 0.001 m/s, curve 2 υ = 0.0005 m/s, and curve 3 υ = 0 m/s
The general solution in Laplace images is as follows:
Let’s mark
Then
The original image F(a, b, c) will be sought by its decomposition into simple fractions
Whereas
then the original image is
where
is a function.
Then
and finally
If the convective component is absent, i.e. υ = 0, then
and
and
From these solutions it is easy to get component Δs, which is describes the effect of convective motion on the diffusion coefficient:
Table 1
The value of the diffusion coefficient for different values of the time t and coordinate r with υ = 0.002 m/s and T= 10,000 K
t/r 0 8 16 24 32 40
0 0.6 0.3728 0.5591 0.6508 0.6800 0.9
2500 0.5582 0.6136 0.6966 0.7897
5000 0.5688 0.6280 0.7087 0.7960 7500 0.5702 0.6299 0.7103 0.7968
10000 0.5704 0.6302 0.7105 0.7969
Table 2
The value of the diffusion coefficient for different values of the time t and coordinate r with υ = 0.005 m/s and T=400 K
t/r 0 8 16 24 32 40
0 0.3429 0.4466 0.5288 0.5906
100 0.4211 0.4618 0.5440 0.6663
200 0.4559 0.4781 0.5601 0.7000
300 0.4762 0.4987 0.5804 0.7196
400
0.5
0.4909 0.5185 0.6001 0.7338
0.9
The results were verified t during the computational experiments for different values of the input parameters. The convective gas movement velocity in underground storage reservoir was calculated by the formula (3), and the diffusion coefficient was determined as shown by the above formulas. The results of calculations are presented in tables and fig. (2-4) for the following values of the parameters l=40 m, D=0.05 (cm2/s), c(r, 0) = 0.06, c(0, t) = 0.6, c(l,t) = 0 9.
The results shown in Fig. 5 and 6 correspond to the following values of parameters l=32 m, D= 0.05 (cm2/s) c(r, 0) = 0.9, c(0, t) = 0.9, c(l,t) = 0.
The analysis of the results shows that the convective component has a significant impact on the gas diffusion process. Despite the fact that the gas flow velocity in porous environments is small, its growth results in increased concentration of admixture.
Fig. 6. Dependence of the diffusion coefficient cz on distance for time t= 400s and different values of the convective velocity υ = {0.004; 0.002; 0} m/s, where curve 1 represents the velocity of υ = 0.004 m/s, curve 2 υ = 0.002 m/s, curve 3 υ = 0 m/s
List of References
1. Varhaftyk N.B. Handbook of the thermal physical properties of gases and liquids / N.B. Varhaftyk. - Moscow: Nauka, 1972. - 720 p.
2. Pyanylo Y.D. Simulation of replacement gases process in porous environments / Y.D. Pyanylo // Applied problems of mechanics and mathematics. - 2011. Issue 9. P. 181-189.
3. Pyanylo Y.D. Numerical model for calculation of the gas flow velocity field in the underground storage layers based on finite element method / Y.D. Pyanylo, N.B. Lopukh, P.P. Galliy// Physical and mathematical modeling and information technology. - 2011. - Vol. 14. - P. 24-29.
4. Pyanylo Y.D. Projection-iterative methods for solving direct and inverse problems of transfer / Y.D. Pyanylo. - Lviv: Spline, 2011. - 248 p.
Article Author
Pyanylo Yaroslav Danylovych
Doctor of technical sciences. Head of Department of the Centre for Mathematical Modeling of Pidstrygach Institute for Applied Problems of Mechanics and Mathematics of the NAS of Ukraine.
