CO₂驱低渗非均质油藏抗高温封窜剂的性能研究

Performance of CO₂ Flooding Plugging Agent for Low Permeability and Heterogeneous Reservoir with High Temperature Resistance

李 凡 罗 跃 肖清燕 丁康乐 汪庐山 刘承杰 刘 巍 刘 磊

LI Fan LUO Yue XIAO Qingyan DING Kangle WANG Lushan LIU chengjie LIU Wei LIU Lei

针对高温低渗非均质油藏CO2驱普遍存在的气窜问题，研制了耐温抗盐CO2气驱封窜剂，考察了其抗盐性和封堵性。在135℃条件下，封窜剂最佳配方为：4.5%丙烯酰胺、0.2%阳离子改性剂、0.2%乳化型引发剂、0.25%甲醛、0.005% N,N'-亚甲基双丙烯酰胺和0.8%缓聚剂。其抗盐能力强，Na+、Mg2+、Ca2+的使用范围分别为：Na+<25 g/L、Mg2+<15 g/L、Ca2+<12 g/L。封堵实验结果表明，成胶时间越长，封堵率越高，成胶时间大于40 h时的封堵率约98%；随着堵剂注入量的增加，填砂管封堵率提高，注入量为0.6 PV时的封堵率可达91.5%；该堵剂有良好的选择性封堵能力，可将高渗填砂管渗透率降低92.5%。对CO2气驱的封窜能力强，可提高原油采收率11.2%。图10表3参10

For CO2 flooding at high temperature in low permeability and heterogeneous oil reservoir, there was a problem of gas channeling. In this study, a research was carried out using a CO2 gas flooding channeling sealing agent which had excellent property of temperature and salt resistance. The dosage of acrylamide, modifier, initiator, formaldehyde, N,N'-methylenebisacrylamide and retarding agent was 4.5%, 0.2%, 0.2%, 0.25%, 0.005% and 0.8% in channeling sealing agent at 135℃. The application scope of positive ion Na+, Mg2+, Ca2+ was obtained as follows: Na+<25 g/L, Mg2+<15 g/L and Ca2+<12 g/L, indicating good salt resistance. The plugging experiment result showed that the longer of gelling time, the better of plugging ratio was. The plugging ratio could basically stabilize at 98% when the gelling time beyond 40 h. With increasing injection volume of channeling sealing agent, the plugging ratio of sand pack model improved. The plugging ratio could arrive 91.5% when the injection volume was 0.6 PV. The system had good performance of selectivity plugging which could reduce the permeability of high sand pack model by 92.5%. It also had strong ability for CO2 flooding and in the CO2 flooding oil displacement experiment, the oil recovery rate could be further improved by 11.2% after plugging.