大庆长垣外围特低渗透扶杨油层CO_2非混相驱油试验研究

大庆长垣外围有3×108t特低渗透的扶杨油层储量在注水开发条件下难以有效动用,为提高这部分储量的有效动用率,开展了CO2非混相驱油试验研究。PVT测试结果表明,扶杨油层原油较稠,体积系数小,膨胀性和收缩性小,溶解系数较低;CO2驱油细管实验最小混相压力为29 MPa,比原始地层压力高8.6 MPa,现场试验为非混相驱;长岩心实验CO2驱油采收率比注水高4~6个百分点。综合室内可行性评价实验结果看,大庆长垣外围扶杨油层开展CO2驱油试验是可行的,并于2003年初在宋芳屯油田南部开辟了注气试验区,有注气井1口,采出井5口。矿场试验结果表明,CO2驱油能够使特低渗透、裂缝不发育的扶杨油层建立起有效驱动体系,从根本上改善其开发效果,该技术有望成为特低渗透扶杨油层有效动用的可行技术。

An CO2 Immiscible Displacement Experimental Study Aiming at Fuyang Extra-low Permeability Layer at Peripheral of Daqing Placanticline

At periphery of Daqing placanticline,there is 3×108 t reserves from extra-low permeability Fuyang layer which is difficult to produce effectively through water flood development.For producing these reserves effectively,an CO2 immiscible displacement experiment is developed.PVT testing result indicates that crude oil of Fuyang reservoir is high-viscosity,low volume factor,low expansibility and contractility,and low dissolubility.At CO2 displacement capillary experiment,the lowest miscible pressure is 29 MPa,which is 8.6 MPa higher than original formation pressure and shows that is an immiscible displacement experiment.Long core experiment shows CO2 immiscible displacements get 4%-6% more recovery efficiency than water displacement.Above laboratory feasibility tests indicate that CO2 immiscible displacement experiment is workable at Fuyang reservoir.At the beginning of 2003,the CO2 gas injection pilot area was built at the south of Songfangtun oilfield.There are 1 gas injection well and 5 production wells.The field test shows that CO2 immiscible displacement can build an effective drive system at extra-low permeability and less fracture Fuyang reservoir,and improve its development effect.This technology is hopeful to be a workable one for producing Fuyang extra-low permeability layer effectively.