致密砂岩油藏注表面活性剂驱油体系提高采收率实验

Experiment on enhanced oil recovery by surfactant-injection oil displacement system in tight sandstone reservoirs

秦正山 周建良 谢晶

中国石油长庆油田分公司第六采油厂，陕西 西安 710000 中煤科工集团重庆设计研究院有限公司，重庆 401331 重庆科技学院石油与天然气工程学院，重庆 401331

No.6 Oil Production Plant, Changqing Oilfield Company, PetroChina, Xi′an 710000, China CCTEG Chongqing Engineering Co., Ltd., Chongqing 401331, China School of Petroleum Engineering, Chongqing University of Science and Technology, Chongqing 401331, China

致密砂岩油藏由于储层物性较差及地层能量不足，自然产能较低，因此需要研究合理的提高采收率方法，以改善此类油藏的开发效果。通过室内实验优选出了具有良好界面活性的非离子氟碳表面活性剂FT-121，和能够有效改变岩石表面润湿性的润湿反转剂FZJ-14，并将两者进行复配，形成了一种新型表面活性剂驱油体系，评价了该驱油体系的注入时机对提高驱油效率的影响。结果表明：在注入压力稳定后，转注表面活性剂驱油体系仅能起到降低注入压力的作用，对驱油效率的影响较小，最终驱油效率仅为37.3%；在注入压力最大时，转注表面活性剂驱油体系提高驱油效率的幅度较大，最终驱油效率为50.8%；而不采用前期水驱，直接注表面活性剂驱油体系提高驱油效率的幅度最大，最终驱油效率可以达到65.6%。因此，致密砂岩储层越早注入表面活性剂驱油体系，提高驱油效率的幅度就越大。这说明表面活性剂驱油体系能够在油田进入高含水期前，通过降低界面张力、改变润湿性、乳化作用及增大波及体积等方式来提高采收率。

Due to poor physical properties and insufficient formation energy, the natural productivity of tight sandstone reservoirs is low. Therefore, it is necessary to study reasonable methods to enhance the recovery rate and improve the development effect of such reservoirs. A non-ionic fluorocarbon surfactant FT-121 with good interfacial activity and a wetting reversal agent FZJ-14 which can effectively change the wettability of rock surface were selected through laboratory experiments. A new surfactant flooding system was formed by mixing the two agents, and the influence of injection timing of oil displacement system on enhanced displacement efficiency was evaluated. The results show that the conversion surfactant flooding system can only reduce injection pressure when the water flooding pressure is stable, and has little effect on enhancing oil displacement efficiency. The final oil displacement efficiency is only 37.3%. The conversion surfactant flooding system enhances oil displacement efficiency greatly when the water flooding pressure is maximum, and the final oil displacement efficiency is 50.8%. Instead of using water flooding of early stage, direct injection of surfactant flooding system can improve the oil displacement efficiency to the maximum extent, and the final displacement efficiency can reach 65.6%. Therefore, the earlier the tight sandstone reservoir is injected with surfactant flooding system, the greater the extent of enhanced oil recovery. This shows that surfactant flooding system can improve oil recovery by reducing interfacial tension, changing wettability, emulsifying and increasing sweep volume before the oil feild enters the high water cut stage.

10.6056/dkyqt202005016