常压页岩储层改造认识与实践

On the Stimulation in Shale Reservoirs under Normal Formation Pressure

国内某常压区块地质构造复杂,存在部分高角度缝,水平应力差异大,人工裂缝易沿高角度缝和最大应力方向延伸,复杂缝网形成困难。地层压力系数小于1.2,压裂液返排困难,测试产量低,商业开发价值小。通过对该区块储层研究,借鉴国内外常压页岩开发经验,采用“密切割非均匀射孔+连续加砂”改造工艺,增加裂缝复杂度,提高改造体积,并针对常压储层孔隙压力低,排采困难,优化电潜泵排采工艺,缩短排采周期,提高常压地层测试产量,实现该常压区块页岩储层商业开发。

The geological structure of a block in China is complex subject to normal formation pressure,where there are some high angle fractures,horizontal stress difference is significant,the artificial fractures are prone to extension along the direction of the high angle fractures and the maximum stress,which gives rise to difficulty to generate complex fracture networks.There is a lower commercial development value due to its formation pressure coefficient of less than 1.2,its difficult flowback of fracturing fluids and its low testing production.Through the study of the block reservoirs under normal formation pressure and the reference of shale development experience at home and abroad,the stimulation treatment of“intensive non-uniform perforation+continuous sand”was adopted to increase the complexity of the fractures as well as the stimulated reservoir volume(SRV).Also,for the low pore pressure in the normal pressure reservoir and difficult drainage and production,such measures were taken as optimization of electric submersible pump drainage and production technology,shortening the period of drainage and production and increase of the production by normal-pressure formation test,so as to realize the commercial development of shale reservoirs in this block under the normal formation pressure.