Integrated Contract EP: Soledad - Pemexcontratos.pemex.com/en/chicontepec/chicontepec_areas/Documents... · the Tamabra formation, featuring proximal, mean and distal slope facies,

Integrated Contract EP: Soledad

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Content

Introduction ............................................................................................................................... 3

Basin Description ...................................................................................................................... 5

Main Features ........................................................................................................................... 9

Exploration and Development History ............................................................................. 15

Production by Field and Reserves .................................................................................... 18

Infrastructure and Hydrocarbons Management .......................................................... 19

Drilling History .......................................................................................................................... 22


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Introduction

The Soledad integrated block is located in the North-Northwest part of the “Activo

Integral Aceite Terciario del Golfo” surface, covering an area of 125 Km2; it is 60 Km NNW

of Poza Rica, Veracruz.

Location of Soledad Block

Geologically, it is located in the South of the Tampico - Misantla basin. Is the only block

with two main fields, Soledad Norte and Soledad; this area was discovered in 1943 upon

drilling the Soledad-1 well, producing from the Tamabra formation, with an initial rate of

44 bpd, 0% water, the well was abandoned after being deemed a non-commercial oil

producer.

492 wells have been drilled on this integrated block; 279 are closed, 27 plugged and 186

are operating. The maximum production was 7,244 bpd oil with 133 active wells in April

1980. Cuurently, (30-06-12) production is 3,403 bpd oil; cumulative production is 39

MMbls oil and 5.7 MMMpc gas. Oil type is light crude; the Soledad Norte field has a

density of 32° API, while it is 37 °API for the Soledad field. The most recent bottomhole

pressure measurement lies between 58 and 125 Kg/cm2. The existing production systems


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in the area are rod pumps and gas lift. The average depth of the tertiary deposits is 1,200

m in the Tertiary.

Some gas shows were observed and the channel samples and cores exhibited oil

impregnation during the drilling of the exploration wells in the Tamaulipas Superior,

Tamaulipas Inferior, Pimienta, Tamán and Tamabra Mesozoic formations.

The following information was obtained through PVT analyses of the Soledad-101 well as

well as various wells near the Block:

• Cacahuatengo-2 Well (located 8 Km south southwest of block):

Tamaulipas Superior Formation: 26.8 °API Oil; gas solubility at initial pressure

relationship (Rsi) of 85.00 m3/m3; Oil Volume Factor (Bo), 1.2801 m3/m3 and a

saturation pressure (Pb) of 146.80 Kg/cm2.

• Presidente Alemán-772 Well (located 71 Km Southwest of block):

Tamaulipas Inferior Formation: 35.7 °API Oil; gas solubility at initial pressure

relationship (Rsi), 179.50 m3/m3; Oil Volume Factor (Bo), 1.6270 m3/m3 and a

saturation pressure (Pb) of 215.20 Kg/cm2.

• Caviar-1 Well (located 128 Km northeast of area):

Pimienta Formation: 15.74 °API Oil; gas solubility at initial pressure relationship (Rsi),

33.28 m3/m3; Oil Volume Factor (Bo), 1.1659 m3/m3 and a saturation pressure (Pb)

of 106.16 Kg/cm2.

• Furbero-106 Well (located 64 Km southeast of area):

Tamán Formation: 37.11 °API Oil; gas solubility at initial pressure relationship (Rsi),

179.60 m3/m3; Oil Volume Factor (Bo), 1.8138 m3/m3 and a saturation pressure (Pb)

of 175.10 Kg/cm2.

• Soledad-101 Well (located within the block):

Tamabra Formation: 31.8 °API Oil; gas solubility at initial pressure relationship (Rsi)

of 163.42 m3/m3; Oil Volume Factor (Bo), 1.4997 m3/ and a saturation pressure

(Pb) of 224.28 Kg/cm2.


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Basin Description

The Tampico - Misantla basin is located in Eastern Mexico and it spans from Southern

Tamaulipas to the Central part of the state of Veracruz, along with a small part of the East

side of the States of San Luis Potosí, Hidalgo and North of Puebla, down to the 200-m

isobaths of the Gulf of Mexico's continental shelf.

Location of Tampico – Misantla Basin

The crystalline basement is formed by igneous and metamorphic rock, their ages ranging

from Permian to the middle Jurassic. In the sedimentary column of the Tampico-Misantla

province, the following tectono-sequences are identified:


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First tectono-sequence (Synrift). Started in the Triassic (250Ma), with the deposition of

continental clasts from alluvial and fluvial environment with some lava flowed from the

Huizachal formation, from the late Triassic age (Noriense-Retiense), over crystalline and

metamorphic basements, later the Huayacocotla formation from the Lower Jurassic

(Hettangiano-Pliensbachiano) was deposited, and it is a sandstones and shale sequence,

from transgressive oceans. By the middle Jurassic, continental conditions were restored,

with Clasts from the Cahuasas formation being deposited, by the end of this period, a new

marine transgression commenced, and favored the deposition of oolithic limestone for

the Huehuetepec formation (Bathonian), and sandy limestone with bioclasts and ooliths

for the Tepexic formation (Callovian), which were overlain by calcareous and

carbonaceous shale with plenty of organic matter, from the Santiago formation

(Oxfordian), deposited on constrained, low-energy seas; as the marine transgression

moved forward, carbonate ramps developed around the basement highs - inside and on

the edge of the former, sandy-clayey limestone and oolithic limestone from the San Pedro

and San Andrés formations were deposited, (Kimmeridgian), respectively, and their lateral

equivalents toward deeper waters, namely, the clayey limestones with scarce bioclasts

and oolites (Chipoco formation) and basin black clayey limestones (Tamán formation).

The transgressive sea conditions continued so that during the Tithonian-Portlandian, a

maximum flooding surface would occur, with most of the basement highs being left in

underwater conditions. During that time, clayey-carbonaceous limestones were

deposited, (rich in organic matter) from the Pimienta formation, from a relatively-deep-

water environment, which is present throughout the region and only in the parts

emerging from the basement, which were under coastal and/or shoreline conditions; La

Casita formation was deposited, which is constituted by glauconitic sandstones.

Passive Margin Tectono-sequence. The marine transgression carried on and ultimately

flooded all of the basement highs, it deposited on the internal parts, limestones and

dolomites, while on the edges, the organic-reefal growths development commenced. At

the same time, and due to the thermal subsidence, the lower areas deepened, giving rise

to deep sea basins, where the three members of the Tamaulipas Inferior formation were

deposited (calcarenithic member, bentonitic member and creamy limestone member)

corresponding to the Berriasian-Barremian age. During the Aptian stage, the Otates

horizon formation deposition occurred, which is considered to be a condensed sequence.

During the Albian, along the entire Tuxpan platform a reef edge, roughly 1400 m thick,

which gave rise to lagoon facies on the inside of the platform, whereas for the reef front,

the Tamabra formation, featuring proximal, mean and distal slope facies, developed due


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to the reefal denudation, and changes facies with the chalky limestone Tamaulipas

Superior formation.

By the end of the Cenomanian, the platform remained under subaerial conditions by a

regressive marine pulse, which was followed by a new transgressive event allowing the

deposition both in lagoon facies and in the mean, distal slope and basin of the Turonian

Agua Nueva (black clayey limestones with black shales interbeddings), Coniacian-

Santonian San Felipe (greenish-grey clayey limestone with abundant olive green bentonite

interbeddings) and Campanian-Maastrichtian Méndez (clayey limestones and green/red

marls) formations; the period of this tectono-sequence ended with the deposition of the

last formation.

Geologic column for the Tampico-Misantla basin with reservoir rock, source rock

(unconventional reservoirs), tectonic events and sedimentary environments

Eventos

TectónicosAmbientes

sedimentarios


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The foreland basin tectono-sequence is characterized by the onset of the Sierra Madre

Oriental's (SMO) uplift, which gave rise to a greater contribution of terrigenous material

sediments; these marine cenozoic depositions were originally defined as Tampico-Misantla

Basin by López-Ramos (1956).

The ongoing uplift of the SMO left very narrow coastal plains and continental shelves,

hence the coastal systems would go from a prodelta to a slope, and where the transport of

sediments by means of turbidity currents prevailed, there would be flow of debris and

landslides, which would produce deposition of submarine fans at the bottom of the

seafloor (basin), overlapping each other and generating submarine erosion during their

development.

By the end of the Cenozoic, deltaic environments prevailed.

Tertiary Sedimentary model (Paleogene and Neogene). Note that delta environments

were deposited above the Chicontepec formation

Tecolutla

Tuxpan

Poza Rica


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Main Features

The main producing formation is Chicontepec, having evidence of production in the

Méndez, Tamabra, Tamaulipas Superior and Tamán from the Upper, Medium Cretaceous

and Upper Jurassic, respectively.

The reservoirs in this Block are located in combined, structural (anticlines with subtle dips

with four-direction closure) and stratigraphic traps.

This block features 56 wells which reached down to the Mesozoic; of these wells, logs for

36 oil and gas producers are available, one from the Méndez formation with an initial rate

of 1,459 bpd, 32 from the Tamabra formation with initial rates ranging between 44 and

1,522 bpd, one in the Tamaulipas Superior formation with a rate of 223 bpd and two in the

Taman formation with initial rates of 2126 and 126 bpd, respectively. There are 16 wells

with gas and/or oil shows during drilling through the Méndez, San Felipe, Agua Nueva,

Tamabra, Tamaulipas Superior, Inferior and Tamán formations; likewise, 50 wells with

impregnations in cores and channel samples were reported in the Méndez, San Felipe,

Agua Nueva, Tamabra, Tamaulipas Superior, Tamaulipas Inferior, Pimienta and Tepexic

formations.

Examples of producing wells in the Mesozoic include: Guadalupe-2 from the Méndez

formation, Soledad-105 from the Tamabra formation, Coyotes-3 from the Tamaulipas

Superior formation and Guadalupe-1 from the Tamán formation.

In the Guadalupe-2 well, significant gas and oil shows were observed in the Méndez

formation - the well flowed mud, gas and oil during 5.25 hours. Four cores were cut at the

Tamán formation, exhibiting very poor light brown oil impregnation. Slightly viscous dark

black oil impregnations were observed In the channel samples from the Agua Nueva

formation, whilst regular light brown oil impregnations were observed in the Tamabra

formation.

One production test was performed in the 55-1765 m interval at the Méndez formation,

producing 1,459 bpd of oil, 1.8% water, GOR 90 m3/m3 through 13 mm production tubing

(TP, in Spanish).


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In the Soledad-105 well, no gas or oil shows were detected during drilling, no cores were

cut, and the channel samples from the Tamabra formation exhibit regular to good oil

impregnation; fracture with slight oil stains were observed in the Tamaulipas Superior and

Inferior Formations.

One production test was performed in the 1970-1981 m interval in the Tamabra formation,

it was treated with acid and flowed 1,522 bpd of oil, 3.4% water and GOR= 128 m3/m3

through 10 mm production tubing (TP, in Spanish).

In the Coyotes-3 well, no gas or oil shows were detected during drilling. Two cores were

cut in the Tamaulipas Inferior (1) and Pimienta (1) formations, exhibiting poor oil

impregnation. Slight oil impregnations were detected in the channel samples from the

Tamaulipas Superior and Inferior formations.

Three production tests with acid treatment were performed, in the Tamaulipas Superior

formation: the first test was performed in the 2139-2152 m interval, drilled and flowed

100% salt water; the second production test was performed in the 2043-2053 m interval -

about 50 - 80% of oil and 1 - 36% water flowed intermittently; a production of 223 bpd oil

was reported, 36% water and GOR 250 m3/m3 - the interval was plugged later on. The

third production test at the 2043-2046 m interval, water with a small amount of oil flowed,

and the test was completed, deeming the section flooded with salt water.

In the Guadalupe-1 well, gas shows were observed in the Tamán formation, high gas

readings in mud, GL from 230 to 180. 12 cores exhibit light to regular oil impregnation in

the Agua Nueva Basal, Tamabra, Tamaulipas Inferior, Pimienta, Tamán and Tepexic

formations. Oil impregnations were observed in the channel samples for the Agua Nueva

Basal, Tamaulipas Inferior, Pimienta and Tamán formations with regular oil spots.

Two production tests with acid treatment were performed in the Tamán formation, first in

the 2941-2949 m interval, flowing 2,126 bpd of oil, 1.8% water, GOR 286 m3/m3; the

second test was performed in the 2923-2928 m interval; a sample was taken whilst flowing

to the battery: 60 - 70% water, pH: 5 - 6.

Comments concerning the events during the drilling through the Chicontepec formation

rocks are provided below:


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492 wells are located in the Soledad block, 468 produced from the Chicontepec formation

at rates between 10 and 509 bpd, with a cumulative production between 10,258 and

497,732 bls, with an average per well of 96,756 bls, evidencing the attractiveness of this

formation.

Relevant events during the drilling of the Chicontepec formation include slight to

moderate gas shows and oil impregnations observed in cores and channel samples, which

were regular to light in the area. Below is a summary of four wells which produced from

this formation.

In the Soledad-118 well, no gas or oil shows were detected during drilling, no

impregnations were observed in the channel samples either.

One production test was performed in the Chicontepec Medio formation in the 1040-1115

m and 1125-1210 m intervals; hydraulic fracturing was performed, yielding a production of

509 bpd oil with 0% water.

In the Soledad Norte-118 well, during drilling through the Chicontepec Medio formation at

1,350 m, moderate gas flow occurred and slight oil, impregnations were observed in the

cores cut at the Chicontepec Medio formation; no impregnations were observed in the

channel samples.

One production test was conducted in the Chicontepec Medio formation at the 1042-1062

m interval; hydraulic fracturing was performed, reporting a production of 308 bpd oil, 0%

water and GOR: 67 m3/m3.

In the Soledad Norte-358 well, no gas or oil shows were detected during the drilling, whilst

slight, viscous oil impregnations were observed in the channel samples at the Chicontepec

Medio formation

One production test was performed in the Chicontepec Medio formation, 1160-1190 m

interval; hydraulic fracturing was performed, reporting a production of 302 bpd oil and 0%

water.

In the Soledad Norte-133 well, no gas or oil shows were detected during the drilling, no oil

impregnations were observed, either.


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One production test was performed in the Chicontepec Medio formation, 1180-1255 m

interval; hydraulic fracturing was performed, reporting a production of 296 bpd oil, 0%

water, GOR: 100 m3/m3.

The wells' geophysical logs were used to produce correlation structural sections; the

seismic information was also used to correlate the Mesozoic formations' distinctive events.

The figure shown below is a correlation section with a W-E orientation - notice the

structural correlation between the Ahuatepec-1, Soledad Norte-94, 187, 284 and 269,

highlighting the fine development of the Chicontepec formation's producing sands, and

that the Ahuatepec-1 well reached the Upper Jurassic formations, where the hydrocarbon

source rocks are, currently considered to be unconventional reservoirs or Oil Shale.

W-E Structural cross section with well logs. Notice the presence of Jurassic rocks in the

Ahuatepec-1 well.

BLOQUE SOLEDAD

SECCION III

Ahuatepec 1

Soledad Norte 94

Soledad Norte 187

Soledad Norte 284

Soledad Norte 269

BLOQUE_SOLEDAD_S3W E

BLOQUE SOLEDAD

SECCION III

Ahuatepec 1

Soledad Norte 94

Soledad Norte 187

Soledad Norte 284

Soledad Norte 269

BLOQUE_SOLEDAD_S3W E

Ahuatepec-1 Soledad Nte-187 Soledad Nte-284 Soledad Nte-269Soledad Nte-94

Sección III

W EJurásico

Cretácico

Terciario


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The following figure shows the same section with seismic information, which shows

attractive Mesozoic rock thicknesses, and evidencing the well-developed Upper Jurassic

formations which are present in the Ahuatepec-1 well.

Seismic cross section, identical to the wells correlation where the presence of Jurassic

source rocks in the Ahuatepec-1 well can be observed.

The Soledad block is located on the north side of the Chicontepec Paleochannel, there is

3D seismic data for 100% of this area, derived from the Amatitlán prospect processed on

2009, and on the south from Cohuca, processed on 2011, and on the Southeast from

Miquetla-Miahuapan, processed on respectively. According to the seismic archives, these

BLOQUE SOLEDAD

SECCION III

Ahuatepec 1

Soledad Norte 94

Soledad Norte 187

Soledad Norte 284

Soledad Norte 269

N

AHUAT-1 SON-94 SON-187 SON-269


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seismic cubes feature pre-stacking time migration, with good quality and optimal vertical

resolution; however, edge effects are present on the boundaries of the seismic cubes,

giving rise to decouplings when two seismic cubes from two different projects are laid side

by side.

In addition, 50 km of bidimensional (2D), 28-seismic segments are available inside the

Soledad block.

The Soledad block features 100% coverage of 3D seismic information from the

Amatitlán, Miquetla-Miahuapan and Cohuca prospects.


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Exploration and Development History

The Soledad block was discovered in September 1944 upon drilling the Soledad-1 well,

which produced 44 bpd from the Tamabra formation, the well was abandoned as non

commercial producer. The first well producer from this area is Soledad-101, drilled in

1961, with a rate of 1,082 bpd, 0% water, from the Tamabra formation; later on, the

Soledad-104 well produced at a rate of 547 bpd and a fractional water flow of 2.6%

from the same formation.

The maximum production reached was 7,244 bpd, with 133 active wells in April,

1980.

In 2010, operation and maintenance activities resumed, reactivating wells with minor

workovers in the Coyotes and Horcones fields, which are East of this Block; it is worth

mentioning that the average well rates prior to reactivation (April 2010) were 20 bpd,

from 79 wells in operation, averaging 1750 bpd a month, whilst currently (July 2012), the

average rate is 30 bpd with 110 wells in operation and an average monthly production of

3300 bpd.

Drilling activity restarted in 2011 and 2012: three horizontal wells were drilled, and to this

day, two have been completed: Coyotes 423D and Coyotes 276D, both completed with

multifraccing (five) and the initial rate for the first one was 400 bpd of 37°API net oil and

0.471 mmmpcd with 30% water cut, which dropped to 15% later on; the initial rate for the

second well was 318 bpd of 28°API oil and 0.093 mmmpcd of gas and 35% water cut,

currently undergoing swabbing, hence the water cut is expected to drop as in the first

well.


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Structural seismic section for Coyotes 423D well with horizontal trajectory.

Coyotes 423 wellbore schematic and geophysical log with the surveyed interval in which

five fractures were performed.

RESULTADOS DE FRACTURAS

GeométricosUnidade

sEtapa

1 Etapa

2 Etapa

3 Etapa

4

Longitud total (m) 210 350 300 335

Xf (m) 105 175 150 167

Altura (H) (m) 240 210 120 70

Network (m) 110 85 100 80

Dirección N29E N34E N31E N34E

Arena Otawa 20/40

(sks) 6100 6801 6875 6286

Fluido Fractura (bls) 4583 4690 3962 3614

RESULTADOS DE FRACTURAS

GeométricosUnidade

sEtapa

1 Etapa

2 Etapa

3 Etapa

4

Longitud total (m) 210 350 300 335

Xf (m) 105 175 150 167

Altura (H) (m) 240 210 120 70

Network (m) 110 85 100 80

Dirección N29E N34E N31E N34E

Arena Otawa 20/40

(sks) 6100 6801 6875 6286

Fluido Fractura (bls) 4583 4690 3962 3614

Resultados de Fracturas

Geométricos Unidades Etapa1

Etapa2

Etapa 3

Etapa4

Etapa 5

Longitud Total (m) 210 350 300 335 165

Xf (m) 105 175 150 167 83

Altura (H) (m) 240 210 120 70 190

Network (m) 110 85 100 80 80

Dirección N29E N34E N31E N34E N33E

Arena Ottawa 20/40 (Sacos) 6100 6801 6875 6286 7384

Fluido de Fractura (bbls) 4583 4690 3962 3614 4431


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Currently, Petróleos Mexicanos has initiated an exploration campaign for the assessment

of geological formations considered to be source rocks, i.e., shale oil, by means of

horizontal wells drilling; the drilling of one exploration well 1.4 km away from this block is

under consideration, its main objective being the Upper Jurassic's Pimienta formation.

Exploration location for the assessment of the Pimienta formation from Upper Jurassic

0

500

1500

1000

2000

2500

3500

3000

NWSE

JS Tithoniano

JS Kimmeridgiano

KS MendezKS SF

KS ANva

KM Tam Sup

KI Tam Inf

Configuraciónestructural cima Fm. Pimienta (m)


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Production by Field and Reserves

The commercial exploitation of oil in this block commenced in 1972 and the production is

associated to the Soledad field reservoir.

The maximum production reached was 7,244 bpd in April, 1980, with 133 active wells

from the Tertiary formations (Chicontepec).

The saturation pressure ranges between 84 to 97 Kg/cm2 and the current pressure ranges

between 58 and 125 Kg/cm2.

Production history from contractual area Soledad

The original oil in place for the block is 1,709.062 MMbl of oil and 1,208.686 MMMpc of

gas; the cumulative production is 39 MMbl of oil and 5.7 MMMpc of gas, with a recovery

factor of 8.0 % for oil and 56.0 % for gas. The estimated 29 remaining reserves are

estimated in 85.780 MMbl oil and 201.057 MMMpc gas.

Original oil in place, production and remaining reserves from contractual area Soledad

0

200

400

600

800

1,000

1,200

1,400

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

02

/66

01

/67

12

/67

11

/68

10

/69

09

/70

08

/71

07

/72

06

/73

05

/74

04

/75

03

/76

02

/77

01

/78

12

/78

11

/79

10

/80

09

/81

08

/82

07

/83

06

/84

05

/85

04

/86

03

/87

02

/88

01

/89

12

/89

11

/90

10

/91

09

/92

08

/93

07

/94

06

/95

05

/96

04

/97

03

/98

02

/99

01

/00

12

/00

11

/01

10

/02

09

/03

08

/04

07

/05

06

/06

Aceite (Bd) Agua (Bd) Gas (mpc/d)

Gas

tos

de

gas

(mp

c/d

)

Ga

sto

s d

e a

ceit

e, a

gu

a (

b/d

)

Área

desarrollada por campo

Volumenoriginal

Factores derecuperación

Producciónacumulada

Reservasremanentes 2P

(Km2)Aceite

(MMbl)

Gas

(MMMpc)

Aceite

(%)

Gas

(%)

Aceite

(MMbl)

Gas

(MMMpc)

Aceite

(MMbl)

Gas

(MMMpc)

125 1,709.062 1,208.686 8.0 56.0 39.00 5.70 85.780 201.057


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Infrastructure and Hydrocarbons Management

Infrastructure in Soledad block

The Soledad block has a gross production of 4,158 bpd, which is processed in the

Soledad I, Soledad II and Palo Blanco separation batteries; from that point, the gas

is transported by a 12” x 2.6 km pipeline, starting in the Soledad I separation

battery, where it is processed and then sent to EC Soledad; it is subsequently sent

to CPG PR. The oil is sent through a 8” pipeline to the Miquetla I separation battery

which leads up to CAB-PR. The Palo Blanco separation battery sends the gas

through a 16” pipeline to EC Soledad and the oil is transported through a 4”

pipeline which starts in BS Soledad I and leads up to CAB-PR.

Production handling for Soledad block


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The block is fitted with the pipelines described below:


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Roads within the Soledad block

Road map (roads and unpaved roads) villages, well pads and oil facilities


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Drilling History

Drill parameters

Depth: 1,600 meters developed

Deviations: 0° to 45°

Mud density

First stage: 1.15 gr/cm³; bentonite mud

Second stage: 1.26 gr/cm³; inverse emulsion

Third stage: 1.30 gr/cm³; inverse emulsion

Objective: Chicontepec

Difficulties during drilling

Surface stage Hydration of clays, circulation losses, drag during lowering of casings, borehole instability and shallow Gas and/or Water flows. Intermediate stage. Reactive shale interbeddings, pipes getting stuck and possible fluid loss, high penetration speeds, possible increases in equivalent circulating density (DEC, in Spanish) due to concentration of cuttings in the annulus and increases in the number of jamming and circulation losses. Production stage Packing, resistance and drag, presence of formation gas, circulation losses, jamming due to differential pressure, bit balling, accumulation of slag in the curved section.

Drill practices

Most of the casing piping (TR, in Spanish) setups in this area correspond to one of two

different designs:

The first design is a 10 3/4" conductor casing, which is intended for the installation of

surface tie-ins and is cemented down to around 50 to 150 m. The 7 5/8" intermediate

casing is cemented at average depths between 400 and 500 m, the setting depth for that


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stage is proposed based on the correlation wells. Finally, the third stage is drilled and

fitted with a 5 1/2" casing which is cemented down to the total depth.

The second design comprises a 9 5/8" conductor casing, intended for the installation of

surface tie-ins and is cemented down to around 50 and 150 m. The final 6 5/8" casing is

cemented down to 1,500 to 1,700 m.

The objective of this section is to review common drilling practices used in the

development of this reservoir; they are listed as a reference and not as a proposed

application of methodology and technology by AIATG.

The first stages are at normal pressure, and are drilled with water-based mud and with

control densities ranging between 1.15 to 1.30 gr/cm3; in the case of abnormal densities,

this is due to the shale stability control and not because it is required by the pressure

gradient. The exploitation stage is drilled with water-based fluid (sodium brine), capable

of increasing its viscosity in case of any contingency; it is also friendly to the production

formation, and the control density can be adjusted.

The Christmas tree dimensions are 10 3/4” x 7 5/8” x 5 1/2” x 2 7/8” 5,000 lb/pg².

No problems were encountered during the drilling process.


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