渤海特稠油油藏油溶性降黏体系辅助热采室内实验研究

Laboratory Experimental Study on Thermal Recovery Assisted by Oil Soluble Viscosity Reduction System in Bohai Extra Heavy Oil Reservoir

海上某深层特稠油油藏埋藏深、原油黏度高(30000~50000 mPa·s)、地层压力高,单纯蒸汽开采易造成注汽压力高、开发效果差等问题,为此,研制了一种油溶性降黏体系,该体系主要由有机溶剂、分散剂和互溶剂组成,并对体系进行了静态评价(闪点、降黏率、溶沥青速率、稠油屈服值)和动态驱替评价。实验结果表明:该体系闪点78.3℃,安全性高,5%质量分数的降黏率可达80%以上,溶沥青速率3.2 mg·(mL·min)-1,可使特稠油屈服值降低93%;动态驱油过程中,相比于单纯蒸汽驱,油溶性降黏体系+蒸汽驱的方式可使注汽压力降低53%,驱替效率提高22%,该体系具有广阔的应用前景,可用于辅助特稠油油藏的热采开发。

A deep extra-heavy oil reservoir in the sea has deep burial depth,high crude oil viscosity(30000~50000 mPa·s),high formation pressure,high steam injection pressure and poor development effect.For these reasons,an oil-soluble viscosity reduction system(mainly composed of organic solvents,dispersants and mutual solvents)was developed.Its static evaluation(flash point,viscosity reduction rate,asphalt dissolution rate,yield value of heavy oil)and dynamic displacement evaluation were carried out.The experimental results showed that the flash point of the system was 78.3℃,the viscosity reduction rate of the system with 5%concentration was more than 80%,and the asphalt dissolution rate was 3.2 mg·(mL·min)-1,which reduced the yield value of extra heavy oil by 93%.Compared with steam flooding alone,the steam injection pressure was reduced by 53%and the displacement efficiency was increased by 22%by oil-soluble viscosity reduction system and steam flooding in dynamic oil displacement process.The system has a broad application prospect and can be used to assist the thermal recovery of extra heavy oil reservoirs.