注CO2过程中沥青质沉淀对低渗储层的伤害及 对润湿性的影响*

Formation Damage and Wettability Change due to Asphaltene Precipitation during CO2 Injection in Low-permeability Reservoirs

钱 坤 杨胜来 黄 飞 窦洪恩 王 千

QIAN Kun YANG Shenglai HUANG Fei DOU Hongen WANG Qian

沥青质沉淀是注CO2提高采收率过程中普遍存在的问题，常导致储层孔喉堵塞和润湿性改变。利用岩心 驱替实验并结合核磁共振技术，定量表征了不同CO2注入压力下沥青质沉淀对低渗透储层的伤害程度和引起的 润湿性变化。结果表明，随着CO2注入压力的增加，采出原油的黏度和沥青质含量不断减小，剩余油中的沥青质 含量不断增加。CO2注入压力分别为9.1、16.2、24.1 MPa时，岩心的渗透率损失率为2.40%、7.41%、8.32%，岩心驱 替后的混合润湿指数下降了0.04、0.12和0.14，表观接触角增加5°、12°、19°。CO2注入压力越高，沥青质沉淀越严 重，对低渗储层的孔隙度和渗透率伤害越大。图8表3参26

Asphaltene precipitation is a common problem in the process of CO2 enhanced oil recovery project，which usually causes the pore throat plugging and wettability change of the reservoir. The formation damage and wettability change due to asphaltene precipitation was quantitatively evaluated under different CO2 injection pressures through core flooding test and NMR technique. The Experiment results showed that the viscosity and asphaltene content of the produced oil decreased and the asphaltene content of the residual oil increased with increasing injection pressure of CO2. When the injection pressure of CO2 was 9.1，16.2 and 24.1 MPa，the permeability reduction of core was 2.40%，7.41% and 8.32%，the mixed wettability index decreased 0.04，0.12 and 0.14，and the apparent contact angle increased 5°，12° and 19°，respectively. The higher injection pressure of CO2，the more serious asphaltene precipitation was，which would result in greater damage to the porosity and permeability of low permeability reservoir.

10.19346/j.cnki.1000-4092.2020.03.028