中康油田高伽马储层压裂工艺技术

Fracturing technology of high gamma reservoir in Zhongkang oilfield

中康油田中康17块腾一中2砂组发育一套高伽马储层,伽马值在100 API^200 API,平均147 API,岩性以砂砾岩为主,高伽马形成原因是由于岩屑组分中火成岩及火山灰含量较高;高伽马储层压裂时应力异常,与该区块常规储层相比,液体效率低,施工难度大,另外由于砂体厚度大,隔层条件差,缝高控制难度较大,早期压裂施工砂堵率高,针对上述情况应用测试压裂技术,求取高伽马储层裂缝闭合压力梯度、近井筒摩阻、压裂液液体效率,滤失系数等参数,为压裂设计优化提供依据,同时综合应用优化射孔、变黏度变排量、支撑剂沉降等缝高控制技术,结合高伽马储层压裂优化设计,确保了施工成功率,提高了改善效果。2014年8月-2015年12月,压裂设计优化27井次,成功率100%,有效率100%。累增油11 410.2 t,平均单井累增油422.6 t,日增油4.1 t,目前大部分井仍继续有效,见到了良好的经济效益。

A set of high gamma reservoir had developed in the middle of first member tengger formation,in Zhongkang 17 block of Zhongkang oilfield,gamma value is between 100 API ~200 API,the average is 147 API.The lithology is glutenite.The phenomenon of high gamma is due to higher content of igneous rock and ash in rock constituents.Compared with the conventional reservoir,stress is abnormal at the time of fracturing, fluid efficiency is low, construction is difficult.Moreover,due to the longer thickness of sand body and poor interlayer condition,fracture height controlling is difficult,plugging rate of fracturing is high in early.To solve these problems,those techniques was applied,including mini-frac,techniques of fracture height controlling,such as optimization of perforation,change of viscosity and pump flow,and so on.Success rate and effect had increased.The technology was applied in 27 wells from2014.8 to 2015.12 in Zhongkang oilfield,the success rate was 100 %,effective rate was 100 %,cumulativet increased oil was 11 410.2 t,average enhanced oil in single well was 4.1 t/d.