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Studies in Surface Science and Catalysis
Advisory Editors: B. Delmon and J.T. Yates
Series Editor: G. Centi
Vol. 151
PETROLEUM BIOTECHNOLOGY
Developments and Perspectives
Edited by
Rafael Vazquez-Duhalt
Institute of Biotechnology
National University of Mexico
Morelos Mexico
and
Rodolfo Quintero-Ramirez
Mexican Petroleum Institute
Colonia San Bartolo
Atephehuacan Mexico
ELSEVIER
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P R E F A C E
Without a doubt, historians will describe 20th and 21st centuries as the oil-based society. One
hundred years ago oil exploitation began, first as a source of energy and later to include oil as
a sourc e of raw ma terial. In addition to the 1 trillion ba rrels that have already been harve sted,
recent estimations shows that about 3 trillion barrels of oil remain to be recovered worldwide,
half from proven reserves and half from undeveloped or undiscovered sources. Oil production
is expected to peak sometime between 2010 and 2020, and then fall inexorably until the end
of this century. After the production peak, the more expensive fuel sources will come into
production. These include hard-to-extract oil deposits, tarry sands, and Synfuels from coal
that requires al ternative or complem entary to conventional oil refining techn ologies.
Our society has an inexorable challenge: to increase the production of goods and
services for people, using new process technology that should be energetically efficient and
environmental friendly. This also will be the case for the petroleum industry. Improvements
in conventional oil refining processes such as cracking, hydrogenation. isomerization,
alkylation. polymerization, and hydrodesulfurization, certainly will occur. Nevertheless, non-
conventional biotechnological processes could be implemented. In contrast to the available
processes, biological processing may offer less severe process conditions and higher
selectivity for specific reactions. Biochemical processes are expected to be low demand
energy processes and certainly environmentally compatible.
The primary target of the petroleum industry is to enhance and maintain a continuous
oil production. Preconceived ideas and misconceptions about biotechnology continue to l imit
the applications of biological processes in the chemical industry. Nevertheless, there are
biotechnological processes that have been demonstrated to be industrially successful and that
are shown to be sufficiently stable, productive and economic for commercial applications.
Even if wastewater treatment and soil bioremediation are common biotechnological
applications in the oil industry, petroleum biotechnology is still in its infancy. Doubtless,
though, biotechnology will play an increasingly important role in future industrial processes.
In this book, experts from 11 countries critically discuss the develop me nts and persp ective s of
biotechnological processes for the petroleum industry.
An integrated approach into the possibility of using petroleum biotechnology
throughout the value chain of an oil company is presented. The authors discuss the eva luation
of biotechnology as a general toolbox for solving some of the technology problems of today
and future possibilities to implement new refinery processes. Petroleum refining could be
enhanced by biochemical reactions in which the specificity exceeds by far these of chemical
reactions. The selective removal of sulfur, nitrogen, and metals from petroleum by
biochemical reactions performed by microorganisms and/or enzym es is discussed. Increasing
supply of heavy crude oils and bitumens has increased the interest in the conversion of the
high-molecular weight fractions of these materials into refined fuels and petrochemicals. This
upgrading has typically been accomplished either with high-temperature and expensive
processes thermal conversion (cracking or coking) or by catalytic hydroconversion. In
contrast to the available processes, biological processing may offer less severe process
conditions and higher selectivity to specific reactions. Enzymatic transformations of
asphaltenes in non- conventional media, and biological upgrading to improve the quality of
certain crude oils and liquid fuels could be envisaged, using biocatalysts to decrease
aromatici ty and sensit ize aromatic heterocycles to subsequent heteroatom removal.
Bioprocessing would complement conventional refining technologies and result in improved
fuel quality at lower capital and operating costs and with reduced environmental impact.
V
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Innovative new processes could be explored, such as methanol production from
methane. Methane monooxygenases are unique among known catalytic systems in their
ability to convert methane to methanol under ambient conditions using dioxygen as the
oxidant. The unusual reactivity and broad substrate profiles of methane monooxygenases
suggest many possible applications in the petrochemical industry. In addition, the ability of
anaerobic bacteria to convert petroleum into methane and thereby generate useful energy is a
very interesting alternative. On the other hand, biological production of hydrocarbons by
bacteria is revisited and its potential is explore d, not only as an environm entally-f riendly fuel
supply, but also as a renewable source for basic petrochem icals.
Microbial colonization of metal surfaces drastically changes the classical concept of
the electrical interface commonly used in inorganic corrosion. Corrosion is a leading cause for
pipe failure, and is a main component of the operating and maintenance costs of gas and oil
industry pipelines. The cost of corrosion to the gas and oil industries was estimated in 2001 to
be about $13.4 billion/yr and of this as much as $2 billion/yr may be due to microbially-
induced corrosion. In order to moderate the economic importance of corrosion in the oil
industry, molecular tools are used to study its microbial complexity.
The current knowledge of the indigenous deep subsurface microbial community in
petroleum reservoirs shows an enormous physiological diversi ty and consti tutes a complex
ecosystem with an active biogeochemical cycling of carbon and minerals. "Souring" of oil
reservoirs by the formation of hydrogen sulfide has been a problem since the beginning of
commercial oil production. Sulfate-reducing bacteria are the culprits that produce this noxious
gas , leading to souring. This microbial process in wastewaters and oil field waters can be
contro lled by another group of microbes, known as nitrate-reducing ba cteria. The use of
nitrate to control microbially-produced sulfide in oil fields is a proven biotechnology that is
grossly u nder-u sed by the petroleum ind ustry. Its effectiveness has been dem onstra ted in
many laboratory investigations and in some field studies. Nitrate has replaced biocides in
some of the oil fields in the North Sea, and the results have been very positive. It is now very
clear that land-based oil field operators should seriously consider using this proven
biotechnology to control, and possibly eliminate, microbially-induced souring and the
problems associated with H2S formation.
Environmentally-related biotechnological processes were pioneered in the petroleum
industry. Oil spil l bioremediation technologies epitomize modern environmental techniques,
working with natural processes to remove spilled oil from the environment while minimizing
undesirable environmental impacts. The application of biological wastewater treatment in the
frame of a process integration treatment technology will hopefully close the water cycle
allowing "zero discharge" in the petroleum industry. Nowadays, water should be considered
as one of the main raw materials of the petroleum industry and its treatment and reuse with
advanced treatment technology should be applied. On the other hand, phytoremediation is an
emerging technology that is based on sound ecological engineering principles, and that has
developed into a more acceptable technology for the remediation of soils and groundwater
polluted with residual concentrations of petroleum hydrocarbons. The advantages of using
phytoremediation include cost effectiveness, aesthetic advantages, and long-term
applicability. Finally, biological air treatment systems are among the established technologies
that can be applied to control volatile organic compounds and odor emissions, and they are
applicable for a wide range of volatile pollutants found in the petroleum industry. Biological
treatment of polluted air emissions results from the competence of active microorganisms,
including bacteria, yeast, and fungi, to transform certain organic and inorganic pollutants into
compounds with lower health and environmental impact. Their applications are growing
continually based on scientific and technological developments.
vi
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The powerful tools of molecular biochemistry can be used to improve the enzyme
stability and efficiency. These techniques may be applied to the particular needs of the
petroleum industry. In addition, the enzymes isolated from extremophilic microorganisms are
extremely thermostable and generally resistant to non-conventional conditions such as organic
solvents and extreme pH. Thus, many enzymes and enzymatic proteins are still to be
discovered.
Rafael Vazquez-Duhalt
The only way to discover the limits of the possible is to go beyond them into the impossible.
(Arthur C. Clarke).
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Table of Contents
Preface v
List of Con tributo rs xiii
Chapter 1
Use of Petroleum Biotechnology throughout the value chain of an oil company:
An integrated approach.
H.Kr. Kotlar, O.G. Brakstad, S. Markussen and A. W innberg
Statoil ASA. Trondheim, Norway
Chapter 2
Petroleum biorefining: the selective removal of sulfur, nitrogen, and metals
J.J. Kilban e II and S. Le Borgne
b
a
Gas Technology Insti tute, Il l inois U.S.A.
b
Insti tuto Mexican o del Petroleo, Mexico 29
Chapter 3
Enzymatic catalysis on petroleum products
M. Ayala and R. Vazq uez-D uhalt
b
a
lnst i tuto Mexicano del Petroleo. Mexico
b
Insti tuto de Biotecnologia, UN AM , Mexico 67
Chapter 4
Prospects for biological upgrading of heavy oils and asphaltenes
K.M. K irkwood, J .M. Foght , and M.R. Gray
Universi ty of Alberta, Canada I 13
Chapter 5
Whole-cell bio-processing of aromatic compounds in crude oil and fuels
J .M. Foght
Universi ty of Alberta, Canada 145
Chapter 6
Biocatalysis by methane monooxygenase and its implications for the petroleum
industry
T.J. Smith and H. Dalto n
3
a
Universi ty of Warwick, United Kingdom
She ffield Hal lam Universi ty, United Kingdom 177
ix
1
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Chapter 7
Biocorrosion
H.A. Videla and L.K. Herr era
h
a
Universi ty of La Plata, Argentina
Universi ty of Antioquia, Colomb ia, 193
Chapter 8
Molecular tools in microbial corrosion
X. Zhu and J.J. Kilbane II
Gas Tech nology Insti tute, Il linois U.SA. 219
Chapter 9
Potential applications of bioemulsifiers in the oil industry
H. Bach and D.L. Gutnick
1
'
b
Tel-Aviv Universi ty, Tel-Aviv, 69978, Israel
a
Ta ro Pharm aceuticals New York, U.S.A. 233
Chapter 10
Anaerobic hydrocarbon biodegradation and the prospects for microbial
enhanced energy production
J.M . Suflita , I.A. Dav ido va \ L.M. Gieg , M. Nanny and R.C. Prince
1
'
"Universi ty of Oklahoma, U.S.A.
b
Exxon Mob il Research and Engineering Co., U.S.A. 283
Chapter 11
Using nitrate to control microbially-produced hydrogen sulfide in oil field waters
R. E.
Eckford and P.M. Fedorak
Universi ty of Alberta, Edm onton, Canada 307
Chapter 12
Regulation of toluene catabolic pathways and toluene efflux pump expression
in bacteria of the genus Pseudomonas
J.L.
Ramos, E. Duque, M.T. Gallegos, A. Segura and S. Marques
Estacion Experimental del Zaidin, CSIC , Granada, Spain 341
Chapter 13
Bacterial hydrocarbon biosynthesis revisited
B. Valderrama
Instituto de Biotecnologia, UNA M. Mexico 373
Chapter 14
The microbial diversity of deep subsurface oil reservoirs
N.-K. Birkeland
Universi ty of Bergen, Norway 385
X
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Chapter 15
Biotechnological approach for development of microbial enhanced oil recovery
technique
K. Fujiwara
11
, Y. Sugai
1
', N. Yazawa
1
', K. O hn o\ C.X. Hong and H. Enomoto
1
a
Chugai Technos Co. Ltd., Japan
Akita U niversity, Japan
c
Japan National Oil Corporation, Japan
PetroChina Company Limited, China
c
Tohoku University, Japan 405
Chapter 16
Phytoremediation of hydrocarbon-contaminated soils: principles and applications
R. K amath, J. A. Ren tz, J. L. Schnoor and P. J. J. Alvarez
University of Iowa, U.S.A. 447
Chapter 1
7
Biological treatment of polluted air emissions
S. Revah* and R . Auria
a
Universidad Autonoma Metropolitana-lztapalapa, Mexico.
b
Universite de Provence, France 479
Chapter 18
Bioremediation of marine oil spills
R. C. Prince and J. R. Clark
ExxonMobil Research & Engineering Co. 495
Chapter 19
Biotreatment of water pollutants from the petroleum industry
E.
Razo-Flores, P. Olguin-Lora, S. Alcantara and M. Morales-Ibarria
Institute Mexicano del Petroleo, Mexico 513
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List of Contributors
S. Alcantara
Institute Mexicano del Petroleo
Eje Central Lazaro Ca rdenas 152. C.P. 07730, Mexico D.F.
P. J. J. A lvarez
Department of Civil and Environmental Engineering, Seamans Center
University of Iowa, Iowa City, Iowa, U.S.A. - 52242
R. Auria
Laboratoire 1RD de Microbiologie, Universi te de Provence
CESB/ESIL, Case 925, 163 Avenue de Luminy 13288, Marseil le Cedex 9 France
M. Ayala
Insti tute Mexicano del Petroleo.
Eje Central Lazaro Cardenas 152, San Bartolo Atepehuacan 07730 Mexico DF, Mexico
H. Bach
Department of Molecular Microbiology and Biotechnology, Tel-Aviv Universi ty
Tel-Aviv, 69978, Israel
N.-K. Birkeland
Department of Biology, Universi ty of Bergen, Box 7800, N-5020 Bergen, Norway
O.G. Brakstad
Sintef Materials and Chemistry, Trondheim, Norway
R. Clark
ExxonMobil Research & Engineering Co.
Annandale, NJ 08801
H. Dalton
Department of Biological Sciences, Universi ty of Warwick
Coventry CV4 7AL, United Kingdom
I.A. Davidova
Institute for Energy and the Environment and Department of Botany and Microbiology,
Universi ty of Oklahoma, Norman, OK 73019, USA.
E. Duque
Estacion Experimental del Zaidin. CS1C
C / Profesor Albareda 1, 18008 Granada, Spain
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R.E. Eckford
Department of Biological Sciences, Universi ty of Alberta
Edmonton, Alberta, Canada T6G 2E9
H. Enomoto
Department of Geoscience and Technology, Graduate School of Environmental Studies,
Tohoku Universi ty, Aramaki, Aoba-ku, Sendai 980-0845, Japan
P.M. Fedorak
Departm ent of Biological S ciences, Universi ty of Alberta
Edmonton, Alberta, Canada T6G 2E9
J. M. Foght
Department of Biological Sciences, University of Alberta
Edmonton, Alberta Canada T6G 2E9
K. Fujiwara
Chugai Technos Co. Ltd.
9-20 Yokogawa-Shinmachi Nisi-ku Hiroshima City 733-0013, Japan
M.T. Gallegos
Estacion Experimental del Zaidin, CSIC
C / Profesor Albareda 1, 18008 Granada, Spain
L.M. Gieg
Institute for Energy and the Environment and Department of Botany and Microbiology,
Universi ty of Oklahoma, Norman, OK 73019, USA.
M.R. Gray
Department of Chemical and Materials Engineering, Universi ty of Alberta
Edmonton, Alberta, Canada T6G 2G6
D.L. Gutnick
Present address, Biotechnology Research Laboratories. Taro Pharmaceuticals U.S.A.,
3 Skyline Drive, Hawthorne, New York, 10532, U.S.A.
L.K. Herrera
b
Faculty of Engineering, Universi ty of Antioquia, Medell in, Colom bia
C.X. Hong
PetroChina Company Limited, Ji l in Oilfield Company
Jil in province, China
R. Kamath
Department of Civil and Environmental Engineering, Seamans Center
University of Iowa, Iowa City, Iowa, U.S.A. - 52242
x iv
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E. Razo-Flores,
Institute Potosino de Investigation Cienti 'fica y Tecnologica
Camino a la Presa San Jose 2055,. C.P. 78216, San Luis Potosi , SLP, Mexico.
A. Rentz
Department of Civil and Environmental Engineering, Seamans Center
University of Iowa, Iowa City, Iowa. U.S.A. - 52242
S. Revah
Department of Process Engineering, Universidad Autonoma Metropoli tana-Iztapalapa
(UAM-I). Apdo. Postal 55-534, 09340 Mexico D.F., Mexico
J. L. Schnoor
Department of Civil and Environmental Engineering, Seamans Center
University of Iowa, Iowa City, Iowa, U.S.A. - 52242
A. Segura
Estacion Experimental del Zaidin, CSIC
C / Profesor Albareda 1, 18008 Granada, Spain
T.J. Smith
Biomedical Research Centre, Sheffield Hallam University
How ard Street, Sheffield SI 1WB , United Kingdom
.I.M.
Suflita
Institute for Energy and the Environment and Department of Botany and Microbiology,
Universi ty of Oklahoma, Norman. OK 73019, USA.
Y. Sugai
Akita Universi ty Venture Business Laboratory
1-1 Tegatagakuen-cho Akita City ,010-8502, Japan
B.
Valderrama
Departamento de Ingenieria Celular y Biocatalisis, Universidad Nacional Autonoma de
Mexico. AP 510-3. Cuernavaca, Morelos, 62250, Mexico.
R. Vazquez-Duhalt
Insti tuto de Biotecnologia, UNAM.
Apartado Postal 510-3 Cuernavaca, Morelos 62250 Mexico
H.A. Videla
Department of Chemistry. College of Pure Sciences, IN1FTA, Universi ty of
La Plata, Argentina
A. Winnberg
Department of Biotechnology, N7465 Trondheim, Norway
x v i
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N .
Yazawa
Technology Research Center, Japan National Oil Corporation
1-2-2 Hamada. Mihama-ku, Chiba 261-0025, Japan
X. Zhu
Gas Technology Institute, 1700 S. Mt. Prospect Rd., Des Plaines 1L 60018
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Studies in Surface Science and Catalysis 151
R. Vazquez-Duhalt and R. Quintero-Ramirez (Editors)
© 2004 E lsevier B.V. All rights reserved.
Chapter 1
Use of Petroleum Biotechnology throughout the value
chain of an oil company : An integrated appro ach.
H.Kr. Kotlar
a
, O.G. Brakstad , S. M arkusse n
c
and A. W innberg
c
.
a
Statoil ASA, R & D Center, Postuttak, N-7005 Trondheim, N orway
Sintef Materials and Chemistry,
b
Dept. Marine Environmental Technology,
c
Dept. Biotechnology, N7465 Trondheim, Norway
1 INTRODUCTION TO AN INTEGRATED APPROACH
The history of biotechnology goes thousands of years back in time. One of the
very first written statements of biotechnology is found in the Bible, telling that
Lot was drinking wine, made through fermentation around 2000 B.C.E. In
modern time Antoni van Leeuwenhoeck was the first to observe a micro-
organism in a primitive microscope in 1684. Louis Pasteur discovered how to
protect against diseases by vaccination, using heat-inactivated organisms,
around 1863. In 2002 the gene sequence of the human genome was completed.
Biotechnology is continuously expanding, and will play an increasingly
important role in future industrial process. Petroleum biotechnology is a very
young and exiting part of these industrial possibilities
It is well established that petroleum reservoirs contain active and diverse
populations of microorganisms. Microbial growth within oil reservoirs has
traditionally been associated with biofouling and souring. Furthermore, the
potentials for microbial improved oil recovery (MIOR) have been investigated
for many decades (see chapter 15)[1]. Recently, nitrate injection was introduced
as a method for curing reservoirs "contaminated" by sulphate-reducing
prokaryotes (see chapter 11)[2]. However, petroleum biotechnology possesses
several other opportunities besides MIOR and nitrate injection. This chapter will
focus on some of these issues.
The primary target of the petroleum industry is to enhance and maintain a
continuous oil production. In 1998/1999 Statoil initiated an R&D program
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looking into the possibility of using petroleum biotechnology as an integrated
approach throughout the value chain of the oil company.
There were three main objectives:
1: Evaluation of biotechnology as a general toolbox for solving some of the
technology problems of today.
2: Investigate future possibilities; e.g. to start refinery processes in the reservoir
using dedicated m icroorganisms.
3: To generate a resource base for new genetic information achieved from the
organisms in the reservoir.
These objectives may be achieved through focusing on biotechnology as a
new business concept of interest to the company. Coverage of all aspects of
biotechnology would be an enormous task. However, the enhanced in-house
understanding of reservoir microbiology has served as a basis for the few
selected areas described below:
. New techniques in exploration and production:
Application of molecular biology techniques as new tools for specific
identification and characterization of hydrocarbon sources during exploration
and production. Samples may come from drill cuttings from exploration
wells; produced oil and formation water; sediments from sea floor seep zones;
etc.
•
Biological well treatments (preventive medication):
Clogging of wells by scaling, hydrates, etc. may be prevented by applying
environmentally friendly biological produced chemicals. This may be
achieved by developing self-sustained, natural existing or bioengineered
microbial populations placed inside the reservoir. The target is to produce
biological substances that can replace traditional chemicals, and that this
remediation will increase treatment lifetime to ensure a continuous oil
production.
•
Bioreactors:
Low energy biological processes for up-grading of oil to improve quality and
thereby reduce penalty pricing. Various types of bioreactors and enzyme
systems can replace traditional catalysts for certain chemical reactions, waste
handling or the production of bio-energy.
•
New application of extremophiles:
New thermophilic and piezophilic enzyme system can enable new bio-
engineering processes and products for applications in the above-mentioned
areas,
or give rise to entirely new products and business opportunities.
Combined approaches of microbiology, biochemistry and DNA technology
are used to obtain microorganisms with specifically designed metabolic
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functions. Such organisms can be applied in reservoirs for the production of
various treatment products or enzymes
in situ.
Thermophilic enzymes may also
be employed to overcome possible fundamental problems related to the growth
characteristics of these microorganisms. Additionally, the "gene-pool" of the
indigenous microbial assemblages of the reservoir have direct implication to the
success of the product in the above suggested business areas.
Environmental aspects/public awareness:
Apart from providing technical
solutions, the outcome of this program will have a great impact on meeting the
environmental challenge of the future. The Norwegian authorities consider many
of the production chemicals applied in the fields today as harmful, and in the
Norwegian sector of the North Sea there is a program for phasing out such
chemicals, replacing them with more environmentally acceptable alternatives.
Biotechnology may provide us with more environmentally friendly alternatives.
Value generation:
This program will contribute to increasing and maturing
the reserve base (upstream), as well as creating business opportunities or
increasing market shares downstream . The Fig. 1 below illustrates the potential
influence of biotechnology throughout the entire value chain within an oil
company.
Fig. 1. Biotechnology throughout the value chain.
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The main challenges are related to:
• The biological activities in a reservoir are still poorly understood. Grow th
control of reservoir microbes, and the knowledge to achieve this control, will
be crucial. In bioreactor-type processes, however, this will be possible.
. There are fundamental questions related to energy pathw ays and reaction rates
that need to be resolved. Direct use of tailor-made enzyme system might
bypass some of these obstacles.
• In bioreactors, the main challenge is to achieve sufficient reaction rates that
are required for a commercial process. This is not a challenge from the
microbiological aspect only, but also from a chemical engineering point of
view.
Acquiring new knowledge: In order to balance the beneficial and detrimental
effects of microbial growth in the reservoir, new knowledge is required. Growth
and possible excretion of products under different reservoir conditions are not
well kno wn . To date, various types of chemicals are injected into the reservoir in
order to maintain or restore oil production, e.g. to counteract or minimize the
influence of scaling, hydrate and asphaltene precipitation. Occasionally,
chemicals and antibiotics are injected to prevent microbial growth. Some of
these chemicals are known to serve as energy source for the microorganisms, i.e.
nitrogen, phosphor and carbon sources. [3-4]. Reservoir conditions vary
significantly, and thus, the microbial communities will respond differently
depending on this external influence. It is imperative to acquire in depth
understanding of the growth and production of microbial products under the
different reservoir conditions. In this respect modeling tools may be used to
simulate how the changes will influence on the indigenous microorganisms.
Joint efforts from internal experts and external collaborators are vital to the
success of this type of projects. Much knowledge on microbial technologies
already exists but the molecular biology approach represents a bold and
important step forward.
The nature of this research requires long-term commitment and support from
the R&D management. A thorough understanding and awareness of the ethical
implications is needed for all involved.
2.
MICROBIAL DNA FINGERPRINT TECHNIQUES IN EXPLORATION AND
PRODUCTION
Several studies have documented microbial communities in hot oil reservoirs
(see chapter 14)[5-9]. Indigenous microbial communities have also been
detected in core samples and water saturated regions of reservoirs [10].
Members of indigenous reservoir communities may include strictly anaerobic
sulfate-reducing prokaryotes [5, 11-12] and methanogens [13-15], as well as
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other microbes [9, 15]. Thus, one would expect to find genetic markers of
microbial activities both during exploration, drilling and production.
Statoil has filed a patent application for utilization of DNA technologies
as a tool for identification and characterization of hydrocarbon sources during
drilling or sampling from sea floor seep zones. Drill cuttings from exploration
wells,
sediments from sea floor seep zones or other specimens could be analyzed
with a selection of specific DNA probes/markers. These specific DNA probes
are taken from microbes found to be linked to different oil producing fields in
the North Sea and other sources. The energy sources for these organisms will be
constituents of the oil, gas or others, specific for the reservoir zones and
conditions of the particular field
This genetic tool may give valuable information on possible migration
routes of the hydrocarbon from the source rock. Specific recognition patterns
might also be used in monitoring different reservoir zones during production,
and further indicate the individual contribution of the particular zone to the
overall production. Possibly, sweep efficiency pattern could be calculated.
Detection of DNA from drill cuttings, sediments, or core samples during
explorative drilling may result in defined species pattern, resulting in indications
of potential hydrocarbon bearing zones (Fig. 2).
Fig. 2. System for characterization of microbes in exploration cores by culture-dependent and
-independent approaches, based on 16S rRNA gene sequencing. The sequences are used for
the generation of DNA probes to be used for screening of cores.
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2.1.
M icrobial diversity in oil reservoirs
It
is essential to establish databases of the microbial ecology in petroleum
reservoirs. Genetic tools for exploration and production can then be developed.
The knowledge of the
in situ
microbial activities should be improved through an
interdisciplinary collaboration between specialists in petroleum exploration and
production, chemists and microbiologists. Understanding the interactions
between the biosphere and the geosphere is essential.
The microbial diversity of two North Sea reservoirs (termed reservoir A and
B) has been studied in some detail [16-17]. Both a culture collection and a 16S
rDNA library have been established for these reservoirs.
2.1.1. Culture independent methods
Culture-independent methods have recently been used for the
characterization of microbial communities in some oil reservoirs [9-10]. In these
studies, DNA was extracted directly from reservoir samples (produced water,
core samples, drill cuttings etc.) This approach was used for the comparison of
microbial assemblages in some North Sea reservoirs with different reservoir
characteristics and production histories. In our studies microbial communities
differed significantly between the reservoirs (Fig. 3). Sequence studies of 16S
rDNA clones from reservoir A showed that 32 % of the clones aligned to the
sulfide reducing thermophile
Archaeoglobus fulgidus,
while bacterial clone
inserts aligned to a variety of types, including Sphingomonas, Herbaspirillum,
Nevskia, Aquabacterium, Alcanivorax, Bacillus
an d
Acetobacterium.
Clones
from reservoir B were dominated by sequences aligning to the a-proteobacteria
Erythrobacter,
the sulfide-oxidizing e-proteobacteria
Arcobacter,
the
halotolerant y-proteobacterium
Halomonas,
and the thermotogales
Geotoga.
Several of the microbial genes detected in our studies have been found in
produced fluids or enrichment cultures from oil reservoirs in the Pacific Ocean
or Canada [9, 18]. The differences in the assemblage compositions between oil
reservoirs and other subsurface structures may reflect the geochemical
influences on the community structures [19-20]. Biodegraded oils dominate the
world's petroleum inventory, and microbial activities play an essential role in
most oil reservoirs [21]. Recent studies have emphasized the impact of an active
potentially indigenous subsurface community [19].
2.1.2. Culture-based methods
Most studies of reservoir communities have been conducted by culture-
based methods [7-8, 22-23]. As a supplement to the culture-independent
characterization of the two North Sea oil reservoirs, culture-based methods were
used to study the diversity of the cultivable microbes in produced fluid from the
reservoirs. Enrichment media for fermentatives, methanogenes, sulfide-
oxidizers, sulphate-reducers and acetogenes were designed, and cultures from
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the two reservoirs showed dominance of small rods, single or in short chains,
and sheathed rods (Thermotogales like). Pure isolates were obtained from only
one of the reservoirs, reservoir A. Even though the enrichments from the other
reservoir, reservoir B, showed a variety of organisms, it was not possible to
obtain any pure isolates from these. The 16S rDNA clones from these
enrichments aligned to
Thermosipho japonicus, Bradyrhizobium
an d
Aquabacterium.
16S rDN A clones from isolates from reservoir A, showed
dominance of Archaeobglobus fulgidus, Methanococcus thermolithotrophicus,
Thermococcus sibiricus
and
Thermosipho japonicus.
Several of the sequences
abundant in the cultures were not found in the clone library from the culture-
independent approach (2.1.1). This is in accordance with other studies [9], and
suggests that several of the predominant members of the enrichment cultures
(e.g.
Thermosipho)
are not the predominant member of the reservoir
communities, but show fast-growing characteristics in several of the culture
media. Other cultures included a-, P-, s- and y-Proteobacteria
Sphingomonas,
Stenotrophomonas, Halomonas meridiana,
an d
Geospirillum,
and the Gram-
positive bacterium
Thermoanaerobacter ethanolicus.
Fig. 3. DGGE analysis of PCR-amplified 16S rDNA sequences from two North Sea oil
reservoirs, reservoir A (1, 2) and reservoir B (3, 4, 5). Only sample 2 contained fluids with
seawater penetration.
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Thermophilic species of
Thermotogales, Archaeoglobus, Thermoanaero-
bacter, Methanococcus
and
Thermococcus
have been reported from high-
temperature oil reservoirs [6-9, 14]. Several of these microbes are typical sulfur-
utilizers, being active in desulphurization of crude oil. These microbes may be
the predominant sources for H
2
S generation rather than typical sulphate-
reducing bacteria, and interestingly several of them were enriched in culture
media designed for SRB.
2.1.3. Detection o f specific micro bes
Monitoring of microbes in the oil reservoir has traditionally been
accomplished by culture methods, e.g. MPN methods for quantification of
viable sulphate-reducing bacteria (SRB), as recommended by the American
Petroleum Institute [24]. Some commercial techniques have also been
introduced, for instance a commercialized immunoassay for semi-quantification
of the SRB-specific enzyme APS reductase [25]. Monitoring may also include
molecular biology methods. Currently, two RNA-based methods are
investigated, fluorescence in-situ hybridization (FISH) and nucleic acid
sequence-based amplification (NASBA). By using RNA detection mainly the
metabolic active cells are assessed. The FISH methods include fluorescence-
labeled DNA probes for the targeting of specific microbes. An example is given
in Fig. 4 where bacteria, archaea, Archaeoglobus, Arcobacter and Erythobacter
are enumerated in production fluids from two reservoirs. These methods may be
further refined for offshore analysis by using field equipment, e.g. the Microcyte
fluorescence cell counter. NASBA is an isothermic alternative to PCR [26].
Real-time miniaturized lab-on-a-chips systems are currently under development
with the NASB A technology as basis [27].
2.1.4. Characterization ofmicrobial dynamics by microarrays
Nucleic acid microarrays have recently been introduced for phylogenetic
identification in microbial ecology. Basically, microarrays consist of series of
specific DNA probes (grabber probes) that are printed on glass slides. Sample
nucleic acids are extracted and labeled (e.g. by fluorescence) and incubated on
the slides, followed by recording. Labeled detector probes may be used for
detection as alternatives or supplements to labeled target DNA [28]. The
microarrays are made quantitative by employing reference DNA to normalize
variations in spot size and hybridization (29). The methods provide a powerful
tool for parallel detection of 16S rRNA genes [30-31] and may be particularly
useful for environmental studies of phylogenetically diverse groups. Although
most arrays are based on the PCR amplification of target genes prior to array
hybridization, systems have also been described where direct profiling of
extracted rRNA from en vironmental sam ples have been used [32 ]. Printed slides
may be broug ht offshore and target genes quantified directly on the platforms by
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portable devices. Arrays have also been established for the assessment of
functional gene diversities and distribution, for instance with genes from the
nitrogen cycling [33-34]. For offshore conditions the sulphur and nitrogen
cycles may be ad dressed during curing of biological sou ring by nitrate injection.
3.
BIOREACTOR: POTENTIAL USE OF BIOCATALYSTS IN CRUDE
OIL UP-GRADING AND REFINING
Until recently, research within oil biotechnology mainly focused on bio-
degradation and bioremediation in connection with clean up after oil spills, and
less on the application of microbial systems in industrial processes. However,
the interest in the latter has been growing the last years, addressing problems
like asphaltenes, high sulfur content, the poor transportability of heavy crudes
due to high viscosity, the presence of heavy metals and polyaromatic/
heterocyclic compounds (see chapters 2, 3, 4 and 5).
The aim of our activity is to use biotechnological processes in up-grading of
"problem" oils/heavy oil and refinery fractions. The overall scope is to define
microb ial/biotechnological technologies along the crude oil value chain that will
give the potential highest cost-benefits, competing with or being superior to
existing methods, or even better, provide solutions where no acceptable methods
exist. In the current program there has been focused on:
Fig. 4. FISH enumeration of the total concentrations of cells (DAPI), bacteria (EUB338),
archaea (ARCH915), Arcoglobus (ARGLO605) and thermotogales (THERSI672) in produced
fluids from tw o North Sea reservoirs, Reservoir A and Resevoir B wl and w2.
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Reduction of the viscosity of heavy crudes through partial degradation of
waxes and/or asphaltenes, thereby increasing the transportability.
Microbial or enzymatic ring opening of polyaromatic hydrocarbons in
refinery distillates in order to increase the fraction of aliphatic com ponents.
Removal of heavy metals such as nickel and vanadium from crude oils
through microbial sequestering, thereby simplifying the subsequent refining
of the crude.
Although chemical means to tackle the above problems exist, they are often
relatively expensive and may lead to pollution of the environment.
Biotechnological processes may represent new and more environmentally
friendly alternatives for value enhancement of heavy oils and partially distilled
petroleum products.
3.1. Pre-refining
Up-grading of crude oils by biocatalytic processes may take place anywhere
from dow n-hole to the refinery; in the reservoir, at the wellhead, d uring tanking,
transport and storage. The pre-refining opportunity is to utilize the time slot
from the start of drainage in the reservoir to the crude reaches the refinery stage.
At any of these stages, a specially designed biocatalyst could be introduced (see
Fig. 1). Although there will be considerable differences between traditional
crude oils and the heavy crudes in physical handling as well as refinery
processes, the chemistry of the compounds that need to be bio-converted could
be close relatives within the same classes.
3.1.1.
Increased transportability by biocatalytic cleavage of heavy com pounds
Extraction, transportation and handling of heavy oils often represent a
problem due to high viscosity. Several classes of molecules are important in
building viscosity. These are asphaltenes, waxes and the more heavy fractions of
polyaromatics. Controlled biodegradation of asphaltenes and waxes in heavy
crudes are highly desirable, as these processes could lead to a substantial
economical gain (see chapter 4).
Wax is degraded by several bacterial species that use the degradation
produ cts for their metabo lic pathways [35-36]. Efficient m ethods for isolation of
wax-utilizing microorganisms with the help of selective media, bacteriophages,
and paraffin wax baiting system have been developed [37-38]. Although the
enzymology of the wax degradation is not understood, some clues have been
obtained through studies of wax biosynthesis by certain bacteria, such as
Acinetobacter spp. [39-40].
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Biodegradation of asphaltenes seems to represent a more challenging
problem - very few publications is found on this subject. However, several
studies have shown that biodegradation of asphaltenes occurs in nature [41], and
that certain bacteria, such as Acinetobacter an d Providencia, proliferate in
environments containing high amounts of asphaltenes [42]. Fungi capable of
"erosion" of hard coal due to the cleavage of asphaltenes have also been
reported [43], as well as combined steam/bacteria treatment of asphaltene
depositions [44]. In addition, biodegradation of bitumen has been observed [45],
and bacteria like
Pseudomona s, Flavobacterium, Acinetobacter,
and
Caulobacter growing on bitumen-contaminated surfaces have been described
[46].
Potential processes are not limited to the natural occurring microorganisms
and their native enzymes. By gene technology it is possible to improve key
enzymes by rational engineering and by use of "gene shuffling" techniques.
These methods make it possible to rapidly "adapt" a given enzyme to new
substrates, or dramatically change the enzyme's properties such as
K
m
,
pH and
tempe rature optimum [47 ]. The modified enzyme(s) may then be introduced
into the appropriate microorganism(s) and its over-production, may greatly
enhance the ability of this microbe(s) to reduce the viscosity of heavy oils.
3.1.2. Demineralization - Biosorption of heavy metals
Demineralization of heavy oils that contain considerable amounts of Ni and
V is an important issue for oil industry due to refinery stage catalyst poisoning.
Several reports describing the use of microorganisms for bioremediation of
environments polluted with heavy metals, suggest that the use of microbes for
demineralization of heavy oils is possible [48-49].
Six mechanisms for microbial resistance to heavy metals have been
described: exclusion by a permeability barrier, intra- and extra-cellular
sequestration, active transport by efflux pumps, enzymatic detoxification, and
reduction of sensitivity of cellular targets to metal ions [50]. For
demineralization of heavy oils, sequestration and enzymatic detoxification seem
to be the most relevant mechanisms to study. In our current work we have just
entered this particular field of research.
3.2. Biocatalytic refining, distillate quality improvements
Perio-refining or post-refining technologies might also be of interest.
Although some of these areas have been addressed elsewhere in this book, we
would like to convey some of our own work (see chapters 2, 3, 4 and 5).
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3.2.1.
Selective ring opening
The mechanisms, the biochemical pathways, and the genetics of degradation
and bioconversion of hydrocarbons in general, and polycyclic aromatic
hydrocarbons in particular have been extensively studied [51-53]. The research
has mainly concentrated on biodegradation and bioremediation in connection
with cleanup after oil spills etc., and less on the application of these systems in
proce sses. How ever, the interest in the latter has been grow ing the last years. In
the petroleum industry there is a desire for products with a larger fraction of
aliphatic components, and thus a higher H/C-ratio, and microbial/enzymatic ring
opening of aromatics may be used to achieve this (see chapter 5).
Development of biocatalysts for aromatic- and heterocyclic ring opening,
including nitrogen compounds such as the polycyclic compound carbazole is of
particular interest. Middle distillate fractions from thermochemical conversion
of heavy oils contain di- and tricyclic aromatics with low fuel value. These are
currently upgraded by expensive high pressure-high temperature chemical
hydrogenation. A Canadian research group [54-55] has suggested an alternative
to thermochemical cracking: "microbial cracking" - a two-step process where
the aromatic rings first are cleaved enzymatically by a blocked mutant under
"near ambient conditions", followed by hydrogenation of the oxygenated
product under mild chemical conditions. Our group is currently engaged in a
project, "Upgrading of crude oils and refined products" involving selective ring
opening of aromatic distillates. In this work, a blocked mutant of
Sphingomonas
is used for studies of bioconversion of aromatic distillates in a bioreactor [56].
Bioconversion of aromatic compoun ds in a real feedstock from crude oil in a
bioreactor system.
The content of polyaromatic hydrocarbons (PAH's) in the
diesel fuels contribute to low cetane numbers and particle emissions from
combustion. The present study focuses on the use of a continuous bioreactor
system for up-grading of light gas oil (LGO) feed stock from the refinery as a
potential industrial process. This is done by biocatalytic ring opening of the
PAH's to generate a more paraffmic diesel fuel.
Two different bacterial strains, Sphingomonas yanoikuyae N2 and
Pseudomonas fluorescence
LP6a 21-41 (donated by Dr. Julia Foght, University
of Edmo nton Cana da), and a mixed blend of six different strains were com pared
for biocatalysis of the PAH's in the LGO feed stock using a fed batch
reactor/semi-continuous reactor.
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Fig. 6. Bioconversion of light gas oil by the specially designed Sphingo monas spp. N2.
In order to apply the concept to a real industrial process, higher degrees of
conversion of the more substituted aromatic compounds are necessary. The
enzyme systems in the PAH degrading pathway of N2 were found to be too
specific. Using the mixed biocatalytic blend a broader range of substrate
conversion was observed. More than 30 % of both the di- and the tri aromatic
compounds were removed from the LGO feedstock; in addition, approximately
30 % of the sulfur containing substrates was removed (Fig. 7). As already
mentioned, the mixed blend had not been genetically modified to terminate the
degradation of PAH's after the ring-opening step. The further uses of this mixed
biocatalytic blend with respect to developing an industrial process; will demand
genetic modification of the strains
The results achieved in the fed batch reactor are now being verified in a
continuous bioreactor to mimic a potential industrial process. Figure 10 shows
the schematic outline of the continuous bioreactor.
In conclusion, microorganisms with biocatalytic pathways that will
selectively convert aromatic compounds in a crude hydrocarbon mixture without
degrading aliphatic compounds exist. Such strains have been used as model
systems for studies of bioconversion of aromatic distillates (LGO) from the
refinery in a bioreactor system.
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Fig. 7. Efficient bioconversion by a m ixed biocatalyst.
The PAH degradation pathway of
Sphingomonas yanoikuyae
DSM 6900
have been genetically modified in order to obtain a recombinant strain that
terminates the PAH degradation after the ring-opening.
The LGO feedstock from the refinery has been shown to have no toxic
effects on the tested organisms,
S . yanoikuyae
mutant N2 and
Pseudomonas
fluorescence
LP6a mutant
21-41,
in concentrations up to 50 vol%. This is of
vital significance, because in an overall technological process it will be of
importance to keep the water volumes as low as possible.
The uptake mechanism and also the substrate specificity differ between the
two strains. The substrate specificity seems to be rather narrow for each
(both) of the strains, non- or mono substituted PAH's were the preferred
substrates.
Importantly, no C is lost by breaking the C - C chains in the blocked
mutants. The organisms are not gaining energy by the reaction. It is of value
that neither the fuel properties nor the cetan number are lost.
A broader range of substrate specificity was observed with a mixed
biocatalytic blend. More than 30% of both the di- and tri aromatic
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compounds and approximately 30 % of the sulfur containing substrates were
removed from the LGO feedstock in a continuous bioreactor system.
In future refinery processes this might replace the energy-expensive
distillation processes. These results suggest that bioreactor systems have the
potential for up-grading of hydrocarbon refinery fractions, heavier distillates and
possibly crude oils. In the years to come governmental regulations will be very
strict on both PAH and sulfur content in the diesel fuel. These preliminary
studies are thought as initial steps in a process of making a more environmental
acceptable diesel fuel with dramatic reduction in both PAH's and sulfur content,
while still maintaining adequate fuel combustion values (Fig. 8). This will be a
bio-upgraded environmental friendly diesel.
Bioconversion for more
environmental friendly diesel fuel
Fig. 8. Bio-reactor for conversion of PAH 's in a real feedstock from crude oil
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Study of pure enzyme vs. whole cell based biocatalysts.
In future investigations
this will include "the aromatic ring opening dioxygenase system". The
Sphingomonas yanoikuyae N2 will be used as a mod el system for comp aring
enzyme and whole cell biocatalysts. In many instances it is an advantage to use
pure enzyme systems instead of whole cells as biocatalysts (see chapter 3).
Enzyme reactions are specific and easy to control, they can be carried out in
non-aquatic environments, and enzymes, as other chemical catalysts, will not
consume carbon i.e. the carbon content in the fuel will be preserved. The
opening of the aromatic ring (e.g. naphthalene, Fig. 9) is a four step enzymatic
process starting with a dioxygenase reaction, then a dehydrogenation followed
by a second dioxygenase reaction and finally an isomerization. The first
oxygenation requires NADH, but the formed NAD
+
is recycled to NADH in the
dehydrogenation reaction. The challenge is to develop a system where this
mu ltistep enzym e reaction could proceed efficiently in a cell free system.
Fig. 9: Metabolic pathway of naphthalene showing the enzymes involved See reference [57],
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3.2.2. Bioreactors
Bioconversion of refinery fractions may take place using growing or resting
cells, "dead" cells, or immobilized cells or enzymes as biocatalysts. Aromatic
ring-opening involves a multistep metabolic pathway. Multistep enzymatic
reactions often require co-factors and/or reducing power (NAD (P) H) that has
to be regenerated or supplied for the enzymatic reaction to take place. Thus,
whole cells, rather than pure enzymes, are often required. The biocatalysts are
usually contained in the aqueous phase and the reaction take place either in this
phase or at the interface between the aqueous and the organic/oil phase. The
components in the refinery fraction that are being up-graded usually show low
water solubility, while the converted products usually are more soluble in the
aqueous phase than in the organic/oil phase. Mass transfer of substrates and
products between the water and oil phase is a major challenge. To achieve
adequate mass transfer, reactors capable of generating a large interface between
oil and water should be chosen. Various types of bioreactors have been
employed by others [58], including stirred tank reactors, airlift reactors,
emulsion phase contactors reactor and fluidized bed reactors. The current
investigation has used stirred tank reactors run in batch, fed-batch and
continuous mode with free growing or resting cells. However, immobilized cells
and enzymes are included in the next phase of studies.
Fig. 10. Schematic of a bioreactor for continuous feed of LGO.
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Continuous processes are well suited for multiphase processes. In the
continuous bioreactor based on a stirred tank reactor in fig. 10, a continuous
stream of substrate (oil phase) is run through the reactor while the biocatalyst (in
the water phase) is recycled. Recycling of the biocatalysts reduces the amount of
water needed in the process. The overall economy of the process is also
dependent upon the lifespan of the biocatalyst and their stability in water/oil
media. In a continuous reactor it is possible to regenerate or boost the
biocatalyst. In the current studies, problems have been encountered connected to
formation of stable emulsions. The emulsion increases mass transfer, but the
stable emulsions made phase separation problematic. Currently, different
approaches are explored to solve this problem.
Enzymes or cells may be immobilized by binding or adsorption to
mem brane surfaces or beads , or by entrapment in a matrix. In a continuous
reactor with an immobilized biocatalyst, it is possible to have a higher
biocatalyst concentration, little or no water in the reactor, and the product
separation is easy. Reactions with purified enzymes might be easier to control
compared to whole cell biocatalysts (see chapter 3). Whole cells may contain
different metabolic pathways and could lead to production of several unwanted
by-products. By co-immobilization of series of enzymes in the water phase of
the reactor, it might be possible to run multi step enzymatic reactions.
Realistic cost of developing new technology.
New technologies are often
met with obstructive arguments. Sentences like "it cannot be done" and "it is
impossible" are customary. Such arguments are "progress killers", and within
the oil industry, new techniques will have to compete with traditional
technolo gy that has been o ptimized for the last 50 years. A lesson can be learned
from the Canadians. None of their syncrude technologies for mining bitumen
would have been available today if they had listened to the "wise guys" 14 years
ago. At that time the operational cost of the technology was more than 30
US$/bbl, today the operational cost is down to around 10 US$/bbl.
The OPEX (operational expenditure) profile (Fig. 11) illustrates the cost
developments in developing new technology for mining bitumen. This curve
profile is believed to be quite universal for most new technology
implementations.
4.
WEL L TREATME NTS TO SECURE CONTINUOUS PRODUC TION
BY PREVENTIVE MEDICATION.
MICROBE S AS SELF-GENERATING SYSTEMS
Preventive medication could be defined as intelligent treatment concepts
performed in advance during the complementation phase, before the impairment
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in productivity occur in the well. The preventive actions are to avoid the onset of
these predicted situations.
With the advance in drilling and completion, increasing number of complex
and expensive wells are being installed, e.g. multilateral, multi-zones, sidetrack
and horizontal. The infrastructures that are in place, such as flow lines and
platforms, also enable the targeting and drainage o f the additional reserves found
near the exiting fields. Very often these additional oil and/or gas are produced
via tieback and satellite facilities. Successful treatments of stimulation, scale
squeeze and tubing deposit removal in these wells can no longer rely on the
traditional method of bullheading. Special tools such as coil tubing and
inflatable plug will be needed to place the chemicals accurately down-hole.
Intervention in these wells will be prohibitory expensive due to tools hire,
personnel and extended period of deferred oil production (tools run). It is
important to realize that for certain type of completion, well re-entry is almost
impossible despite accepting the financial penalty. There is clearly a need to
develop an intervention free system for these wells that allow the flow of oil
unhindered and preferably with the chemicals pre-delivered down-hole.
Syncrude Canada OPEX
Fig. 11. OPEX profile in developments of new technology for mining bitumen. The curve
shows the measured cost until 1998, then the further projection. T he bars in 99 , 00 and 01 are
the actual cost. (M aurice B. Dusseault, personal communication).
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4.1. Preventive treatment: Increased productivity by self-generating- or
more en vironmental friendly treatment system/processes (scale, hydrate,
asphaltenes, w a x , etc.)
The generation of effective production chemicals could be achieved using a
self-sustained, natural existing or bio-engineered, microbial population. This
will protect and free the well from most other intervention treatment and could
be of great economical interest to an oil company, enhancing both well recovery
and well productivity.
This will imply the search for microbes that have the genetic machinery to
produce certain treatment chemicals (i.e. organic acids, enzymes, surfactants,
antifreeze-proteins etc). Alternatively, genetic engineering could be used to
introduce this capability to the organisms. Such organisms could be introduced
to the near well bore area by various means (i.e. squeezed with/without solid
support, immobilized, combined with nutrients, etc), to produce the treatment
chemicals.
If the organism is not fit for life under the reservoir conditions, the bacteria
can be used in bioreactors to produce the desired product.
Bypassing the problems of placements:
Correct placement of the treatment
fluids is of crucial importance to the overall treatment success. Numerous
treatments have failed due to poor placement. Nonetheless, in many wells,
especially in gravel packed wells, uniform placement is difficult to achieve.
With this new technology placement should no longer be the problem.
The strategies of this new technolog y are illustrated in fig. 12 and include:
Placement of the treatment during the completion stage. This can be done
either by bullheading the specially designed organism together with nutrients
into the formation, or by coiled tubing (CT) deployment.
Use of porous particles soaked with the product placed inside the gravel
packs at the completion face.
Use of micro encapsulation, with the desired microorganism together with
nutrition inside the capsules. Inject far beyon d the critical matrix in the well.
If successful, this concept constitutes the only possible self sustained and
lasting method by which production chemicals can be produced in situ and to
allow wells to operate free of most interventions.
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In situ production of treatment chemicals
Fig. 12. Schematic view of in situ production of treatment che micals.
4.2 Green treatment products
In order to prove the basic concept of the above-mentioned technology of
preventive medication for secured production, the following approaches have
been made:
A synthetic gene, coding for polyaspartate (polyAsp), has been cloned in
E.coli. In a construct with 75 basepairs, coding for 25 am ino acids, with a fusion
protein included, the polyAsp polypeptide was expressed in the host cell.
Most service companies in the oil industry are supplying polyAsp as a
combined scale - and corrosion inhibitor. Recently, polyAsp has also proved to
be an efficient bridging agent, boosting the squeeze lifetime of traditional scale
inhibitor jobs. PolyAsp is classified as a green treatment product, being more
than 60 % biodegradable and non-toxic. From 2005 the Norwegian government,
through chart 12 and the Norwegian Pollution Authorities, SFT, will implement
a "zero harmful discharge" policy for the Norwegian sector of the North Sea.
This will focus the search for more environmental friendly treatment products.
On shore bioreactor: E. coli
will not survive during reservoir conditions.
However, the bacteria can be used in bioreactors to produce the desired product.
Bioreactor production of PolyAsp might prove to be economically feasible.
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23
Down hole:
Work is in progress, introducing the corresponding synthetic
gene construct into a vector, compatible with extremop hiles. This is a first step
towards down hole application
5. NEW APPLICATION O F EXTREMO PHILES IN OIL RELATED
INDUSTRY
5.1. Bioprospecting of the gene pools
Oil quality may be linked to microbial growth in oil reservoirs. This has
been substantiated in fields with biodegraded heavy oils. Although biogenic
reservoir processes seem to be slow [21] oil is utilized as carbon source and
water as a source of inorganic nutrition. The reservoir microbes, acting at high
temperature and pressure, have preferences or tolerance for these extreme
conditions. Enzymes from extremophilic microbes may be tailor-made for
industrial systems run at high temperature and pressures, i.e. systems in which
enzymes from mesophilic microbes will not function. Such enzyme systems
may be utilized inside the reservoir, in bioreactors, in waste handling or in
energy processes. DNA technology may be used to link appropriate enzyme
systems to microbes growing at relevant temperature and/or pressure conditions.
An immediate prerequisite for the utilization of microbes and enzymes from
the hot oil reservoirs will be to perform surveys of the genetic pools within the
reservoirs. The knowledge about microbial species in these environments is
constantly increasing, but the understanding of the interactions between the
microbes and their environments is still limited. It will be essential to
characterize active enzyme systems in the reservoirs. Complete genomes have
been sequenced for several microbes detected in oil reservoirs, including
Archaeoglobus fulgidus an d Methanococcus jannaschi [59-60 ]. Recent progress
in molecular microbial ecology has revealed that traditional culturing methods
fail to represent microbial diversity in nature, since only a small proportion of
viable microorganisms in most environmental samples are recovered by
culturing techniques. Methods to investigate the full extent of microbial
genomes in nature include the use of BAC (bacterial artificial chromosome)
vectors or random shotgun sequencing techniques [61-62]. These approaches
also have potentials for characterization of the complete genomic structures in
oil reservoirs. Besides explaining microbial structure-function relationships in
the reservoirs, the genomic libraries may be excellent tools for prospecting of
novel biocatalysts [63].
5.2.
Thermophilic/extremophilic enzymes
New application of extremophilic/thermophilic enzyme systems:
The concept
is to investigate the commercial utilization of thermophiles. These organisms
have enzyme systems working at high temperature, and often at high pressure.
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Such enzymes are tailor-made as catalysts in industrial processes performed at
extreme conditions. Enzymes from most mesophilic microbes will not function
as the high temperature will denaturate their proteins (e.g. the enzymes). Such
enzyme systems will work placed either inside the reservoir, in bioreactors, in
waste handling or in energy processes.
5.3. Future prospective
The petroleum biotechnology is still in its infancy and will play an
increasingly important role in the future industrial processes. Within the oil
company it will have a substantial economical impact throughout the value
chain. This will influence on the development of:
New techniques in exploration and production
Biological well treatments (Preventive medication)
Biocatalytic up-grading of oil
New application of extremophiles
Acknowledgement
The authors would like to thank Statoil for the permission to publish this
book chapter and for their support in the "Applied Biotechnology" program.
Many thanks to our special adviser, Hakon Rueslatten, for valuable help and
discussions.
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Studies in Surface Science and Catalysis 151
R. Vazquez-Duhalt and R. Quintero-Ramirez (Editors)
©2 004 Published by ElsevierB.V. 29
Chapter 2
Petrole um biorefining: th e selective remo val of sulfur,
nitrogen, and m etals
J.J. Kilbane II
a
and S. Le Borgne
a
Gas Technology Institute, 1700 S. Mt. Prospect Rd., Des Plaines, Illinois 60018
b
Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, Col. San
Bartolo Atepehuacan, 07730 Mexico D.F., Mexico
1. INTRODUCTION
The quality of petroleum is progressively deteriorating as the highest quality
petroleum deposits are preferentially produced. Consequently the concern about
the concentrations of compounds/contaminants such as sulfur, nitrogen, and
metals in petroleum will intensify. These contaminants not only contribute to
environmental pollution resulting from the combustion of petroleum, but also
interfere with the processing of petroleum by poisoning catalysts and
contributing to corrosion. The selective removal of contaminants from
petroleum while retaining the fuel energetic value is a difficult technical
challenge. New processes are needed and bioprocesses are an option. Existing
thermo-chemical processes, such as hydrodesulfurization, can efficiently remove
much of the sulfur from petroleum but the selective removal of sulfur from
compounds such as dibenzothiophene, the removal of organically bound
nitrogen, and the removal of metals cannot be efficiently accomplished using
currently available technologies. The specificity of biochemical reactions far
exceeds that of chemical reactions. The selective removal of sulfur, nitrogen,
and metals from petroleum by biochemical reactions performed by
microorganisms and/or enzymes has been demonstrated. However, further
research is needed before biorefining technology can be commercialized. This
chapter reviews the status of biorefining and discusses topics requiring further
research.
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The geochemical conversion of organic matter into petroleum is a slow
and inefficient proce ss. It is estimated that 23.5 tonnes of plant m aterial/biomass
are required to form a single liter of petroleum during geological periods of time
[1]. Moreover, the current rate of energy consumption is 400 times greater than
the capacity of the planet to produce biom ass. It beho oves us to utilize our fossil
fuel legacy as efficiently as possible while avoiding environmental damage.
Environm ental regu lations limit the amount of sulfur oxides em itted to the
atmosphere by the combustion of fossil fuels by regulating the concentration of
sulfur in these fuels. In particular, transportation fuels are severely regulated.
For example, the permissible concentration of sulfur in diesel has been
progressively decreased over the past decade from 500 ppm to 10 to 15 ppm [2].
Environmental regulations do not specify concentration limits for nitrogen and
metals in transportation fuels, but such regulations may be forthcoming as these
compounds inhibit the catalytic converters used to cleanse exhaust gases from
vehicles. The future use of petroleum products to power fuel cells may provide a
further impetus to decrease the sulfur, nitrogen, and metal content of petroleum
derived fuels as reforming catalysts and fuel cell electrodes are sensitive to
Recommended