Reservoir Performance Under Gas Injection, LL-453 Area, Bolivar Coastal Field, Venezuela
- D.L. Stepanek (Creole Petroleum Corp.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- March 1960
- Document Type
- Journal Paper
- 34 - 36
- 1960. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 5.1.1 Exploration, Development, Structural Geology, 4.2 Pipelines, Flowlines and Risers, 4.6 Natural Gas, 4.1.6 Compressors, Engines and Turbines, 5.2.1 Phase Behavior and PVT Measurements, 2.4.3 Sand/Solids Control, 4.1.5 Processing Equipment, 4.1.2 Separation and Treating, 3 Production and Well Operations, 2.2.2 Perforating, 5.4.2 Gas Injection Methods, 4.9 Facilities Operations, 5.8.5 Oil Sand, Oil Shale, Bitumen, 1.6 Drilling Operations
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The Tia Juana conservation plant No. 2, which furnishes high pressure gas to pressure maintain four Eocene sandstone reservoirs of the prolific LL-453 area of the Bolivar Coastal field, was placed in operation during April, 1597. This is Creole Petroleum Corp.'s largest gas conservation plant to be constructed on Lake Maracaibo to date, and is capable of compressing 300 MMcf/D to 1,800 psig. The four reservoirs being pressure maintained extend over a surface area of 10,400 acres, with each having an average net oil-sand thickness of 114 ft. During the first 28 months of plant operation, an average total of 205 MMcf/D of gas was injected into the four reservoirs. This represents approximately 99 per cent replacement of hydrocarbon volume withdrawals. The total efficient producing rate of these reservoirs is 135,000 BOPD with a gas-oil ratio of 1,050 scf/bbl. The highly effective gravity segregation taking place throughout the reservoirs contributes quite heavily to the excellent reservoir performance experienced to date, under both natural depletion and pressure maintenance. Although gas injection has only been in operation for approximately 28 months, the beneficial effects are readily apparent from the production characteristics of up-dip wells. These wells have shown decreasing trends in gas-oil ratios accompanied by an increase in production rates. Furthermore, recent subsurface pressure surveys have indicated definite pressure increases in the up-dip portion as a result of the gas injection.
Reservoir Characteristics and Development History
The LL-453 area is located on Lake Maracaibo, approximately 11 miles southwest of the community of Tia Juana, Venezuela. The pressure maintenance area covers a surface area of 10,400 acres and consists of two B-6-X and two underlying B-7-X Eocene sandstone reservoirs, each of which has a net oil-sand thickness (when averaged together) of 114 ft. Structurally, the reservoirs are gently dipping monoclines bounded down-dip by essentially immobile water legs, up-dip by eroded or truncated zones resulting from the Major Miocene-Eocene Unconformity and laterally by major faulting. Shown in Fig. 1 is a structural map of the LL-453 pressure maintenance area. The total sand-section thickness of the B-6-X and B-7-X sands (when considered together) varies between 0 to 400 ft, depending on the structural position.
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