低渗透烟道气驱油藏冻胶封窜体系性能研究

Study on Performance of Gel Plugging Agent for Flue Gas Flooding in Low-permeability Reservoir

针对红48井区低渗透烟道气驱油藏极易发生气窜的问题,开展了适用于烟道气驱油藏的冻胶调堵剂预案研究,并评价了其耐酸性能及封堵能力。实验选用200万低分子量聚丙烯酰胺为主剂,构建酚醛冻胶体系。该体系在42℃地层温度下成胶强度较高,弹性模量可达10.23Pa。CO2对酚醛冻胶的成胶时间、强度及冻胶长期稳定性无明显影响。物理模拟实验表明,低渗岩心中,0.5%200万分子量聚合物黏度仅为23.62mPa·s,成胶液黏度低,极易注入低渗透地层。岩心封堵实验表明,该冻胶体系耐冲刷性能较好。水驱70PV后冻胶封堵率仍可达到99.45%,经3轮次CO2-水交替注入后,CO2驱封堵率为91.81%,水驱封堵率为90.19%。CO2环境下酚醛冻胶仍具有很好的封堵能力,可作为低渗透烟道气驱油藏调堵用剂。

In view of the problem that gas channeling is very easy to occur in the gas flooding of the low-permeability reservoir of Hong48 well block,a gel plugging agent for flue gas flooding reservoir was studied,and its acid resistance and plugging ability were evaluated.Using the polyacrylamide of 2 million low molecular weight as the main agent,the phenolic gel system was constructed.The system has high gelling strength under the formation temperature of 42℃,and the elastic modulus of the gel can reach to 10.23 Pa.CO2 has no significant effect on the gelation time,strength and long-term stability of the phenolic gel.The physical simulation experiments show that in low permeability core,the viscosity of polymer solution of 0.5%with 2 million molecular weight is only 23.62 MPa·s,and the viscosity of gelling fluid is low,so it is easy to inject into low permeability formation.The core plugging experiments show that the gel system has good scouring resistance.After 70 PV of water flooding,the plugging rate of the gel can still reach 99.45%.After three rounds of alternate injection of CO2 and water,the plugging rate of CO2 flooding is 91.81%,and the plugging rate of water flooding is 90.19%.Phenolic gel still has good plugging ability under CO2 environment,and can be used as a plugging agent for low permeability gas flooding reservoir.