胜利油田G89-1区块CO2气驱封窜剂的性能评价

The Laboratory Performance Evaluation of CO2 Gas Flooding Channeling Sealing Agent in Block G89-1 of Shengli Oilfield

李 凡 罗 跃 丁康乐 刘承杰 刘 巍 安 科 王 鼎

LI Fan LUO Yue DING Kang-Le LIU Cheng-Jie LIU Wei AN Ke WANG Ding

胜利油田G89-1区块属于高温、低渗、非均质油藏。针对该油藏研发了耐温抗酸CO2气驱封窜剂，其配方如下：丙烯酰胺4.5%（质量分数，下同），N,N-亚甲基双丙烯酰胺0.05%，改性剂0.3%，乳化型引发剂0.25%, 甲醛溶液0.25%，缓聚剂ES0.5%。该凝胶溶液的pH为3~7时，成胶时间可控制在6 h左右，受pH影响较小，形成的凝胶在126℃、pH = 3条件下放置3个月，黏度基本无变化。封窜剂体系在126℃、CO2压力0~10 MPa条件下，成胶黏度达到150×104mPa·s以上。该凝胶的抗剪切性能良好，在183 s-1下搅拌20 min后，黏度仍达62×104 mPa·s。填砂管封堵实验表明，该体系能显著降低地层渗透率，注水冲刷40 PV后封堵率大于90%。填砂管驱油实验表明，该体系有很好的CO2封窜性能，同时能进一步提高原油采收率9.32%。

The Block Gao89 of Shengli oilfield belongs to high temperature, low permeability and heterogeneous oil reservoir. Aimed at the reservoir, a recipe of CO2 gas flooding channeling sealing agent (CGFCSA) was optimized as followed: the dosage of AM was 4.5% (mass fraction, the same below), the dosage of N,N-Methylenebisacrylamide was 0.05%, the dosage of modifier was 0.3%, the dosage of initiator was 0.25%, the dosage of formaldehyde was 0.25% and the dosage of inhibitor ES was 0.5%. The performance of the CGFCSA was probed; the sealing and oil displacement experiments were carried out. When the gel solution of pH was 3-7, the gelling time could be controlled within about 6 h and pH value had little effect on it. When the gel was put into the environment for 3 month at 126℃ and at pH=3, the viscosity changed little. the viscosity of the channeling sealing agent was more than 150×104 mPa·s when the pressure of CO2 was between 0 and 10 MPa at 126℃. The shear performance of the gel was perfect, , the viscosity was 62×104 mPa.s after sheared at the speed of 183 s-1 for about 20 min. The physical model test showed that the system could reduce the permeability remarkablely, , the plugging rate was more than 90% after water flooding of 40 PV. The sand pack of oil displacement experiment showed that the system had good performance of sealing channeling for CO2 and the EOR could be further improved by 9.32%.