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Reservoir Primary Recovery Mechanisms
- 1. PRIMARY RECOVERY MECHANISMS BY:KUSIIMA PATRIC
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- 3. PRIMARY RECOVERY MECHANISMS Liberation and expansion of solution gas Influx of aquifer water Contraction of reservoir rock skeleton Expansion of original reservoir fluids - Free gas, if present - Interstitial water - Oil, if present • Gravitational forces The natural energy of the reservoir is utilized during the initial production of hydrocarbons.
- 4. •Solution gas drive/ Depletion drive •Gas-cap drive •Water drive •Gravity-drainage drive •Combination drive Ultimate oil and gas recoveries vary depending on the drive mechanism. RESERVOIR EFFECTIVE DRIVE RECOVERY RANGE ,% OIL WATER DRIVE DEPLETION DRIVE 25-40 GAS WATER DRIVE 80% Gas Reservoir Drive Mechanisms Volumetric reservoir (gas expansion drive) Water drive Oil Reservoir Drive Mechanisms
- 5. • Gas liberationfrom the crude oil and the subsequent expansion of the solution gas as the reservoir pressure is reduced CP LIQUID GAS P T 20%40% 60%80% X PiA B C A. Original Conditions B-C. Partially depleted SOLUTION GAS DRIVE Pr
- 6. Oil A. Original Conditions B-C.Partially depleted Oil producing wells Oil producing wells SOLUTION GAS DRIVE
- 7. DEPLETION DRIVE MECHANISM Pressurebehavior: Declines rapidly and continuously. Gas–oil ratio: increases to maximum then starts to decline Water production: no water production. Oil recovery: 5%-30%
- 8. GAS CAP DRIVEMECHANISM • Expansion of gas cap and solution gas as it is liberated. Cross Section Oil producingwell Oil zone Oil zoneGas cap
- 9. GAS CAP DRIVEMECHANISM ULTIMATE OIL RECOVERY • Size of the original gas cap • 2) Vertical permeability Good vertical permeability will permit the oil to move downward with less bypassing of gas. • 3) Oil viscosity • 4) Conservation of the gas • Oil production rate. Critical gas saturation, decreased increased • Dip angle(up to 60% or greater oil recovery) KgeffKoeff
- 10. Characteristic Trends Oil Recovery20% to 40% OOIP Reservoir pressure Declines slowly and constantly Gas-Oil ratio Rises constantly Water Production None Well Behavior Reservoir pressure maintained GAS CAP DRIVE MECHANISM
- 11. NATURAL WATER DRIVEMECHANISM An aquifer provides the energy for hydrocarbon production. Both water expansion, as a result of pressure reduction, and inflow are involved.
- 12. Different Water DriveMechanisms Oil producing well Water Water Cross Section Oil Zone water leg underlies the entire reservoir Oil producing well Cross Section Oil Zone Water Edge Water Drive only part of the areal extent is contacted by water, Bottom Water Drive
- 13. CHARACTERISTIC TRENDS Reservoir pressureRemains high Gas-Oil ratio Remains low Water Production Starts early and increases to appreciable amounts Well behavior Flows until water production is excess Oil recovery 35 to 70% OOIP WATER DRIVE MECHANISMS
- 14. GRAVITY-DRAINAGE DRIVE MECHANISM Initialfluids distribution in an oil reservoir Gravity drainage secondary gas cap Initially undersaturated Difference in densities of the reservoir fluids. Characteristic Trend Secondary gas cap Initially Undersaturated Reservoir pressure Rapid pressure decline without gas cap Gas-Oil ratio Low due to gravity segregation Ultimate recovery • High vertical • Production rate similar to the gravity drainage rate • Low viscosity
- 15. COMBINATION DRIVE In combination-drivereservoirs, • Depletion drive and a weak water drive, • Depletion drive with a small gas cap and a weak water drive. The example shows a combination of natural water influx and gas cap drive.Water production Increasing water production rates Reservoir pressure Increasing water production Gas-Oil ratio Continually increasing Gas- Oil ratio
- 16. PRIMARY RECOVERY MECHANISMS BY:KUSIIMA PATRIC