低渗透油藏二氧化碳混相驱油机理数值模拟

二氧化碳混相驱是大幅提高油藏采收率的重要增产措施,但目前对二氧化碳驱油机理的研究多停留于室内实验阶段,对其混相驱油机理和影响因素缺乏全面系统的认识,因此,采用油藏数值模拟研究方法,以大情字油田黑59井区低渗透油藏为例,对二氧化碳混相驱油机理和影响因素进行了系统研究,对比了注水和注二氧化碳开发的效果。结果表明,注二氧化碳提高采收率的驱油机理是,二氧化碳溶于油相中增加了油藏流度,其与油相组分交换达混相,从而达到提高驱油效率的目的。注二氧化碳开发单井产油量可达注水开发的2倍以上,最终采收率提高14%以上,为研究区及同类低渗透油藏注二氧化碳混相驱开发提供了理论指导,为现场方案的实施提供了重要依据。在吉林大情字油田黑59井区实施混相驱方案后,初期平均单井产油量达10.2 t/d,是注水开发最高产油量的2.4倍,含水率下降了23.2%,与理论研究结果一致。

Numerical simulation of CO2 miscible flooding in low-permeability oil reservoir

CO₂ miscible flooding is a important oil recovery enhancing measure,but the studies on the mechanism of CO₂ miscible flooding are mostly limited in laboratory now,the mechanism and influencing elements of CO₂ miscible flooding are not well understood systematically so far,therefore,the numerical simulation is used in Hei59 block of Daqingzi oilfield which selected as the pilot area to study the mechanism,at the same time,water-injection and CO₂-injection is studied comparatively.As the result, the oil recovery enhancing mechanism of CO₂ miscible flooding is that the CO₂ gas is dissolve into rude oil to improve the fluid mobility and exchange ingredients with oil phase until they reach miscibility status in order to improve oil displacement efficiency considerably,and the individual well producing rate through CO₂ driving is about two times than that through water driving,and the ultimate recovery can by increased by above 14%through CO₂ driving than water driving,and the study can provide valuable theoretical instruction for CO₂ miscible flooding in this reservoir and other similar oil fields and can provide important proofs for practical projects.After the CO₂ miscible flooding project was executed in Hei59 block of Daqingzi oilfield,the individual well producing rate reached 10.2 t/d,2.4 times that that through water driving,and the water cut is declined by 23.2%,the practical production status accords well with theoretical studying.