一种高温低渗透油藏CO₂气驱封窜剂的制备与驱替效果评价

Research and Displacement Efficiency of a Channeling Sealing Agent for High Temperature and Low Permeability Oil Reservoirs

李 凡 罗跃 丁康乐 刘承杰 刘 巍

LI Fan LUO Yue DING Kang-Le LIU Cheng-Jie LIU Wei

开发了一种适用于高温低渗透油藏的 CO2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120×104 mPa·s以上。封窜剂体系在126℃、CO2压力8.0 MPa、矿化度57728.92 mg/L条件下，成胶黏度达到170×104 mPa·s以上。在直径2.5 cm、长120 cm、渗透率1.631 μm2的填砂管中，水驱注入压力为0.08 MPa，成胶后，CO2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CO2有较强的封堵作用；岩心驱油实验表明，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为5.1%。

By screening of the inhibitor, the initiator and the modifier of the channeling sealing agent, a CO2 gas flooding channeling sealing agent which had excellent properties and was suitable for high temperature and low permeability oil reservoirs was developed. The composition of the channeling sealing agent is as followed: the dosage of AM was 4.5 % (mass fraction), of initiator was 0.25%, of modifier was 0.3% and of inhibitor was 0.5%. At room temperature, the viscosity of the channeling sealing agent solution is 1.1 mPa·s, hence, it was easy to be pumped and injected. At 100℃, the gelling time was controlled within 2.5-12 hours through changing the dosage of inhibitor, and the viscosity was above 120×104 mPa·s accordingly. For the channeling sealing agent in salinity of 57728.92 mg/L, its viscosity was more than 170×104 mPa·s when the pressure of CO2 reached 8.0 MPa at 126℃. In a sand pack with a length of 120 cm, a diameter of 25cm and the permeability of 1.631 μm2, the pressure of injection water is about 0.08 MPa, and the pressure of CO2 flooding was around 2.2 MPa after gelation. In a word, the system was easy for injection, and had a strong plugging ability for CO2 gas flooding. The parallel core experiment showed that the system had good performance of sealing channeling for CO2 and the EOR could be further improved by 5.1%.