延长油田低渗透油藏二氧化碳驱油影响因素室内实验研究

The Laboratory Investigation of CO_2 Flooding Influence Factors for Low-permeability Reservoir in Yanchang Oilfield

针对延长油田低渗透油藏,通过开展岩心注气物理模拟实验,探索提高低渗透油藏CO2驱油开发效果影响因素及其规律。实验表明,不同驱替压力下,注入压力越高,采收率越高,注入压力高于最小混相压力后,采收率不再增加,采收率最高可达66.68%;并且注入压力增加,气体突破时间延迟;注入速度越高,采收率和换油率越高,CO2驱油开发效果越好,生产汽油比也越高;岩心渗透率高于1.26×10-3μm2时,渗透率增大,采收率差别不大,但相比水驱,采收率提高程度较大;岩心渗透率低于1.26×10-3μm2时,渗透率增大,采收率增大,但相比水驱,采收率提高程度较小。

In view of the low-permeability reservoirs of Yanchang Oilfield, the influence factors and law of CO2-EOR are explore by laboratory physical simulation experiment for core gas injection. The laboratory result shows that the recovery increased by the gas injection pressure increase until the minimum miscible pressure, the peak recovery is 66.68 %, and the high injection pressure can delay the gas breakthrough; by the higher speed of CO2 injection, there is higher oil exchange ratio and gas-oil ratio; when the permeability is more than 1.26×10^-3μm^2, the recovery is similar, but compared water-flooding the EOR value is higher than the value below 1.26×10^-3μm^2.