高含水稠油油藏CO2复合体系驱油机理OA

Taking a low-permeability ordinary heavy oil reservoir in the middle and deep layers of Daqing Oilfield as an example,the key mechanisms of enhancing oil recovery by CO2 composite systems(CO2 with foaming agent and CO2 with polymer solution)were ex-plored through laboratory experiments.The injection parameters of the composite systems were optimized using numerical simulation method,and their application effect was predicted.The research results indicate that the dissolution of CO2 in crude oil can fully utilize its energy-increasing and viscosity-reducing effects,with a pressure increase of up to78%and a viscosity reduction rate of up to48%.Injecting the plug of CO2 with foaming agent or CO2 with polymer solution into production wells has good adaptability to low-permeabili-ty,heterogeneous,and high water-cut heavy oil reservoirs after water flooding.It has the effects of pressure increase,water control,profile control,and oil enhancement,but the timing,stability,target,and effect of the two CO2 composite systems are different.It is recommen-ded to use the plug of CO2 and polymer solution to seal high water-cut oil wells.The suitable CO2 injection intensity is around 37.5 t/m,and the injection intensity of polymer solution is around 175 t/m.The on-site application effect shows that compared to water flood-ing,injecting CO2 composite system can increase the production of high water-cut heavy oil reservoirs by 2.2 times and reduce the water cut by 18.5%.