二氧化碳驱油注入方式优选实验

Optimization experiment for carbon dioxide flooding injection mode

针对二氧化碳(CO2)驱油注入方式优选问题,选择连续注气、水气交替注入、周期注气3种方式对低渗透岩心进行室内对比实验,同时对3种注气方式的主要参数(注气压力、速度、比例、段塞大小)以采出程度、水/气突破时间为评价标准进行优化研究。结果表明:随着驱替压力及注入速度增加,见气采出程度和最终采出程度逐步增大后趋于稳定,最佳注入压力为26 MPa,最佳注入速度为2.4 cm3/min;水气交替水气比为1∶1时,最终采出程度最高,水、气突破时间较为接近;从最终采出程度看,水气交替最佳段塞为0.20 PV;周期注气最终采出程度随着注气段塞的增加而增大,小周期注入量有利于推迟见气。从见气采出程度和最终采出程度综合考虑,周期注入段塞0.03 PV最佳。

In order to optimize CO2 flooding injection, continuous gas injection, water and gas alternate injection, cycle gas injection are chosen to carry out experiments, and the main parameters（gas injection pressure, speed, proportion and slug size） of the three gas injection modes are optimized according to recovery and water/gas breakthrough time. The conclusions are as follows： with the increase of displacement pressure and injection rate, gas breakthrough recovery and ultimate recovery increase, then gradually stabilize, the optimum injection pressure is 26 MPa, the optimum injection speed is 2.4 cm3/min; when water/gas ratio is 1∶1, ultimate recovery is the highest and water/gas breakthrough time are very close; for ultimate recovery, the best slug is 0.20 PV; with the increase of the slug of cycle gas injection, ultimate recovery increases, smaller cycle injection slug is conductive to the later gas breakthrough. For gas breakthrough recovery and ultimate recovery, 0.03 PV is the best.