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开发了一种适用于高温低渗透油藏的CO_2气驱封窜剂,通过对封窜剂配方中缓聚剂ES、引发剂、改性剂加量的筛选,得到封窜剂的最佳配方如下:丙烯酰胺加量4.5%(质量分数,下同),乳化型引发剂INI-E(甲苯溶液)加量0.25%,改性剂(阳离子单体)加量0.3%,缓聚剂ES加量0.5%。该封堵剂溶液在常温下的黏度为1.1 mPa·s,易泵送易注入。100℃下成胶时间可控,在2.5~12 h左右,成胶黏度达到120×10~4mPa·s以上。封窜剂体系在126℃、CO_2压力8.0 MPa、矿化度57728.92 mg/L条件下,成胶黏度达到170×10~4mPa·s以上。在直径2.5 cm、长120 cm、渗透率1.631μm~2的填砂管中,水驱注入压力为0.08 MPa,成胶后CO_2驱替的突破压力为2.2 MPa,实验表明该体系的注入性好且对CO_2有较强的封堵作用。岩心驱油实验表明,该体系有很好的CO_2封窜性能,同时能进一步提高原油采收率5.1%。
A CO_2 gas flooding and sealing agent suitable for high temperature and low permeability reservoirs has been developed. The optimal formulation of sealing agent is obtained by screening the amount of retarder ES, initiator and modifier in the sealing agent formulation As follows: Acrylamide plus 4.5% (mass fraction, the same below), emulsifying initiator INI-E (toluene solution) plus 0.25% modifier (cationic monomer) plus 0.3%, retarder ES Quantity 0.5%. The plugging agent solution viscosity at room temperature 1.1 mPa · s, easy to pump easily injected. 100 ℃ plastic time controllable, in about 2.5 ~ 12 h, plastic viscosity reached 120 × 10 ~ 4mPa · s or more. The sealing agent system reached a viscosity of 170 × 10 ~ 4mPa · s at 126 ℃, CO_2 pressure of 8.0 MPa and salinity of 57728.92 mg / L. In the sand filled tube 2.5 cm in diameter and 120 cm in length with a permeability of 1.631 μm 2, the injection pressure of water flooding is 0.08 MPa and the breakthrough pressure of CO_2 flooding after the gel formation is 2.2 MPa. Experiments show that the system has good injectability And CO 2 has a strong blocking effect. Core flooding experiments show that the system has a good CO 2 sealing channeling performance, while further enhancing the recovery of crude oil 5.1%.