Application of Hydrocarbon Gas Miscible Flooding for Water Flooded Reservoir

摘要

Within the next decade, the potential for application of gasrnmiscible flooding process can be enormous, particularly, inrnthose reservoirs currently under waterflood. In general,rnreservoir pressures of these oil fields are maintained atrnrelatively high pressure, which is favourable for application ofrngas miscible flooding. We conducted a feasibility study torninvestigate the application of hydrocarbon gas misciblernflooding in an oil field in Middle East offshore area. This oilrnfield has a plan to utilise the high pressure hydrocarbon gasrnproduced from deeper gas formation beneath the target oilrnreservoir, as the injection gas. A series of laboratory tests,rncomprising of: (1) Phase behaviour tests, (2) Slim tuberndisplacement tests and (3) Composite core displacement tests,rnwere conducted to characterise the miscible process in therncrude oil-injection gas system. With the help of phasernbehaviour tests such as swelling test and multiple-contact test,rnthe equation of state (EOS) parameters were fine-tuned. Thernminimum miscibility pressure (MMP) was determined by thernslim tube displacement tests and also a set of representativernEOS parameters were successfully verified by simulating slimrntube displacement performance. As the MMP is still below therncurrent reservoir pressure, the composite core displacementrntests were conducted to evaluate the displacement efficiencyrnat the current reservoir pressure as the tertiary oil recoveryrnafter water flooding. The test results showed that more thanrn80% of residual oil after water flooding could be recovered.rnFinally, the compositional reservoir simulation studies for thernsector model of the target oil reservoir were conducted and itrntoo, indicated that hydrocarbon gas miscible flooding could bernfeasible in such a high water-saturation oil reservoir.