低渗稠油油藏蒸汽-CO_2-化学剂复合吞吐研究

Study on composite steam stimulation with carbon dioxide and chemical agents of low permeability heavy oil reservoir

叙利亚O油田SH-B油藏为典型的低渗孔隙型块状碳酸盐岩稠油油藏,因埋藏深、渗透率低、原油黏度大等特点,注气困难,注气质量差,蒸汽吞吐开采效果差。通过室内实验和数值模拟研究了注蒸汽-CO_2-化学剂复合吞吐的效果,结果表明,CO_2伴注具有增溶、膨胀、降黏、改善储层渗透性等功能;高温驱油剂(BM02#)在质量分数为0.3%时即可有效降低界面张力、改变岩石润湿性、降低注气汽压力、延缓蒸汽突破时间、扩大蒸汽波及体积的作用,提高驱替效率10%;油溶剂(OSVR)质量分数为5%时降黏率可达78.3%,且能有效降低注气启动压力以及注气压力,驱替效率提高16%。热化学复合蒸汽吞吐较之纯蒸汽吞吐,第一周期产油量提高49.4%,最终驱替效率提高25.7%,可有效改善油藏开发效果,提高采收率。

Reservoir SH-B of O oilfield in Syria is a typical porous carbonate bearing heavy oil characterized by low permeability, deep buried depth and high viscosity. On cycle steam stimulation （CSS） recovery, it is difficult to inject the steam and therefore, the development effect is unsatisfactory. Effect of composite steam stimulation with carbon dioxide and chemical agents is studied by means of laboratory experiments and reservoir numerical simulation in order to solve the problems of how to inject steam into reservoir easily and how to improve the steam quality. It shows that injected CO2 has the functions of solubilizing, swelling, viscosity reduction and formation permeability improvement. The pyrochemical oil displacement agent （BM02 # ） at 0.3 % concentration can effectively reduce the interracial tension, change the rock wettability, lower the steam injection pressure, and put off the breakthrough time of steam to expand the steam swept volume and enhance the displacement efficiency of 10%. Oil solvent （OSVR） at 5% concentration can get high viscosity reduction rate up to 78. 3%. It can also effectively lower the steam injection start-up pressure and steam injection pressure, and enhance the displacement efficiency of 16%. Compared with CSS, composite steam stimulation with CO2 and chemical agents can effectively improve the development effect and enhance the recovery factor. The first cycle production is increased by 49.4% and the final displacement effect is enhanced 25.7%. This method provides the basis for making the development plan of SH-B reservoir.