pH值响应性液流转向剂对自生CO2调驱效果优化研究与应用

Optimization research and application of pH responsive fluid flow direction agent affecting in-situ generated CO2 flooding

关键词:  自生CO₂  渤海油田  多轮次  液流转向剂

Key words:  in-situ CO₂  Bohai oilfield  multi-round  fluid diverting agent

摘要:

针对渤海油田多轮次自生CO₂调驱效果逐渐递减的问题,通过室内物理模拟实验分析了原因,并提出一种利用pH值响应性深部液流转向剂优化自生CO₂调驱效果的方法。岩心驱替实验表明:一轮常规自生CO₂调驱采收率可在水驱基础上提高25.61%,二轮调驱已无增油效果；二轮调驱时加入0.1 PV凝胶,采收率可在一轮常规调驱基础上提高6.11%,但驱替压力由0.07 MPa增至0.7 MPa,表明凝胶体系能够改善调驱效果,但注入性差；二轮调驱时加入0.1 PV的pH值响应性堵剂,注入压力在0.05~0.35 MPa波动,最终采收率可在一轮常规调驱基础上增加12.33%,且调驱后注入压力无明显增加,表明堵剂具有良好的注入性,不影响后续注水。2015年和2018年,分别在渤海油田A区块开展了两轮次现场试验,一轮为常规自生CO₂调驱,措施后累计增油1 371 m³；二轮为自生CO₂优化调驱,措施后累计增油2 317 m³,较第一轮增油效果明显改善。

Abstract:

In order to solve the problem that the effect of multi-round in-situ CO₂ flooding as gradually decreased in Bohai oilfield, the reasons were analyzed through lab physical simulation experiments, and an optimization method for in-situ CO₂ generation technology was proposed by using a pH-responsive plugging. The results of lab experiments showed that the recovery of in-situ CO₂ generation in first round of profile control increased 25.61% on the base of water flooding, the second round had no effect of oil increase. When 0.1PV gel was injected in second round of profile control, the recovery rate increased 6.11% on the basis of first round, but the injection pressure increased rapidly from 0.07 MPa to 0.7 MPa, it was indicated that the gel system could improve oil recovery, but the injectivity was poor. The injection pressure would fluctuate between 0.05 MPa and 0.35 MPa when 0.1PV pH-responsive plugging agent was added in second round of profile control, and the final recovery increased 12.33% on the basis of first round. Displacement pressure did not increase significantly after the adjustment of flooding, which showed that the plugging agent had good injectivity and would not effect the water injection. In 2015 and 2018, two rounds of field tests were conducted in block A of Bohai oilfield. The first round was conventional in-situ CO₂ generation, and the cumulative oil increase was 1 371 m³. In the second round, optimization in-situ CO₂ generation was carried out, then the cumulative oil increase was 2 317 m³ , which was significantly better than the first round.