Al Shaheen Field....

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A Proposed Drilling and Cementing Plan of Al Shaheen Oil Field

A Plan Project

Presented to Dr. Michael A. Aloria,

College of Engineering, Architecture and Fine Arts

BATANGAS STATE UNIVERSITY

Gov. Pablo Borbon Campus II

Alangilan, Batangas City

In Partial Fulfillment

of the Requirements for the Subject

PetE-552: Drilling Fluids and Cementing

Baldon, Jhon Fernan B.

De Los Reyes, Ray Mark T.

Red, Roxanne M.

PETE-5101

September, 2014


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INTRODUCTION

The Al Shaheen Oil Field is an offshore oil and gas production field

located in the north east coast of Qatar in the Persian Gulf north of Doha. It was

discovered in 1992 and started its production in 1994. Maersk Oil Qatar AS

operates the field under a production sharing agreement with Qatar Petroleum,

on behalf of the state of Qatar. The field produces oil and gas from the Kharaib,

Shuaiba, and Nahr Umr formations, it is described by low permeability, limited

thickness, and geological complexity. The current production of oil is 240,000

barrels per day and the gas production is estimated about 220 million cubic feet

per day.

A successful oil field operation depends on several factors including a

drilling and cementing plan. It must assure the safety and health of the public,

also the environmental aspects must be considered. The hydrocarbon recovery

should be economic to support


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1. Formation Tops

Figure 1.

The field consists of a sequence of thin, stacked reservoirs dominated by

carbonates causing a tight matrix. Within the sequence a highly permeable, but

thin sandstone unit exists. Hydrocarbons have been discovered in formations of


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Jurassic and Cretaceous ages with the Cretaceous reservoirs being the most

prolific.

The carbonate reservoirs are characterized by relatively thin oil columns

with a large areal extent (25 km by 45 km) with typical matrix permeability in the

1-10 milli Darcy (mD) range. The trapping mechanism at the Cretaceous

reservoir level is interpreted to be structural closures, for some reservoirs

possibly in combination with hydrodynamic forces, fault seals and lateral facies

changes.

Kharaib B, Shuaiba and Nahr Umr are the main producing reservoirs. The

Kharaib B and Shuaiba are both carbonate reservoirs, while Nahr Umr is a clastic

sandstone reservoir. The Shuaiba reservoir is a transitional marginal carbonate

platform with a full thickness of approximately 200 ft. The reservoir has tight

carbonates with inter and intra granular porosity and local natural fracture

networks. The Nahr Umr consists of a thin heterolithic oil- and gas bearing

reservoir. The reservoir consists of laterally extensive marginal marine sands

with a target thickness of some 2 to 25 ft of high permeable sand. The Kharaib B

is a laterally continuous limestone of relatively uniform thickness of approximately

80 feet, comprising local natural fracture networks. The reservoir quality varies

within the thickness as the reservoir gradually coarsens upward.

1.1. Surface Formation

1.1.1.Simsima Formation


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The Limestone of Simsima in the subsurface commonly

contain inter particle fracture, moldic and vuggy porosity while the

dolomite has good inter crystalline porosity. Shallow water

carbonate sediments, associated with secondary porosities and

good permeabilities are the only oil bearing strata in Al Shaheen

Field

1.1.2.Halul Formation

The Lime Stone of Halul formation exhibits low to moderate

reservoir characteristics with moderate porosity and low

permeability.

1.1.3.Fiqa Formation

Fiqa Formation is an efficient impermeable, thick seal owski

with low hydrocarbon source rock potential. It is a sequence of

moderate shallow to deep marine shale, consisting of lime stone,

marl and shale. The amount of clay varies and Shargi has the

maximum concentration. Drilling the Fiqa reveals complications

similar for those encountered when drilling very reactive clay/shale

formation.

1.1.4.Laffan Formation

Laffan Formation in Sirri oil fields is a shale formation

comprising kaolinte clay mineral and calcite and quartz cement. It

has a very low permeability. Laffan is a relatively thin and brittle

formation but the presence of organic-rich layers and being buried


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at deeper depth has improved the chance of its lateral continuity

and can be classified as a good seal.

1.1.5.Mauddud Formation

The Mauddud Formation rests conformably on the Nahr Umr

Formation and is defined by the change from the clastic rocks of

the Nahr Umr. In the subsurface north area, the lower part of the

Mauddud Formation is called the lower marly member and

represents a transitional zone between the Nahr Umr clastics and

the limestones proper of the so-called Upper Mauddud.

The formation consists mainly of Orbitolina-bearing

limestone with local basin margin rudist buildups in the offshore

North field of Qatar and northeast Iraq. Extensive dolomitization,

with wide variations in both extentand texture, has been reported

from both outcrops and wells. The JurassicCretaceous pelagic

strata are probably the possible source for the Mauddud Formation

oil in northern Iraq, whereas indigenous sources in the Mauddud

strata and Nahr Umr shales, as well as the Upper Jurassic rocks,

are probably the source rocks in the southern parts in the basin.

Porosity of 1035% and permeability of 10110 md have been

reported from different fields of the basin. This porosity is attributed

to a combination of dolomitization, fracturing, and dissolution.


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1.1.6. Khatiyah Formation

The offshore facies, which differ by the occurrence of dense,

microporous lime mud-stone, wackestone and packstone. This

formation contains foraminitera and codiacean algae. The shallow

water depositional environment wa deeper than the characteristics

of near area however,the presence of hard grounds with bored

surfaces is indicative of non-depositional intervals and the

extensive bioturbation equally suggest relatively shallow water

conditions.

1.2. Target Zones

1.2.1. Shuaiba Formation

The Shuaiba Formation (Aptian) is a thick, porous shelf

carbonate, present in the subsurface over much of the Arabian

Gulf. It is the uppermost formation of the Thamama Group (Lower

Cretaceous), and is overlain by the Nahr Umr Formation (Albian)

and overlies the Kharaib Formation (Barremian).

1.2.2. Nahr Umr Formation

The Nahr Umr consists of a thin heterolithic oil- and gas

bearing reservoir. The reservoir consists of laterally extensive

marginal marine sands with a target thickness of some 2 to 25 ft of

high permeable sand.

1.2.3. Kharaib B Formation


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The Kharaib B is a laterally continuous limestone of relatively

uniform thickness of approximately 80 feet, comprising local natural

fracture networks. The reservoir quality varies within the thickness

as the reservoir gradually coarsens upward.

Figure 2.


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2. Depth to Oil, Gas, Water & Minerals

Figure 3.

Based on the figure, the formation that contains hydrocarbon deposits

among the surface formations is the Khatiyah formation. The target zones

include the Nahr Umr sandstone, Shuaiba limestone and the Kharaib sandstone.

The Shuaiba formation is a low permeability carbonate rock.


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3. Pressure Control

Figure 4.

4. Casing

Surface Casing

Size: 18.625 in Location: Laffan Formation

Depth: 2,900 ft Hole Section: 24 in

The surface casing is used to cover the upper aquifer loss zones.


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Intermediate Casing

Size: 13.375 in Location: High Formation

Depth: 6,000 ft Hole Section: 16 in

The intermediate casing is used to case off the cretaceous hydrocarbon

bearing zones.

Upper Production Casing

Size: 10.759.625 in Location: Sudair Formation

Depth: 10,700 ft Hole Section: 12.25 in

The upper production casing is used to shut off the potentially weak zones

in the Qatar and Jubaila Formation

Production Liner

Size: 7 in Location: Median Anhydrite

Depth: 14,400 ft Hole Section: 8.5 in

The production casing covers the Khuff reservoir zones.

5. Cement

5.1. Amount, Type, Density, and Yield of Cement

24 inch section

Amount: Density:

Type: Yield


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16 inch section

Amount: Density:

Type: Yield

12 inch section

Amount: Density:

Type: Yield

8 inch section

Amount: Density:

Type: Yield

6. Circulating Medium

6.1. Type and Characteristics of mud for each section of hole, and

description of standby mud.

24 inch section

Amount: Density:

Type: Yield

16 inch section

Amount: Density:

Type: Yield

12 inch section


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Amount: Density:

Type: Yield

8 inch section

Low Solid Non- Dispersive (LSND) Water based- drilling mud

Amount:9.3- 9.6 ppg Density:

Type: Yield:

7. Testing, Coring, Logging

8. Pressures, Temperatures, LCZs, H2S

9. Other Aspects of the Proposal

Additives

Sodium Chloride (NaCl)

Calcium Carbonate (CaCO3)

DUOTEC- NS Xantham Gum

PAC- UL Polyionic Cellulose

Polysal

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