深层页岩天然裂缝群发育下缝网压裂优化方法——以川南地区LH-7井为例

Optimization method of fracture network fracturing in deep shale with natural fracture groups:a case study of Well LH-7 in southern Sichuan Basin

川南地区深层页岩气区块天然裂缝发育情况变化较大,压裂期间容易发生滤失严重、井间压窜等现象,对页岩气井缝网压裂效果存在显著影响。开展深层页岩地层天然裂缝群影响下的压裂缝网扩展模拟,并根据天然裂缝群特征针对性地进行缝网压裂参数优化,减少天然裂缝群造成的不利影响,有助于改善压裂效果,降低施工风险,提高气井最终采收率。文中构建了深层页岩天然裂缝群发育下的压裂缝网扩展模型,以川南地区LH-7井为例,绘制了天然裂缝群发育井段压裂优化设计系列图版,提出了裂缝发育井段压裂参数优化设计流程。该井采用压裂液变黏变排量缝网压裂设计,压裂液总量增多0.75%,缝网体积扩大14%,缝网建造效率提高13%,优化效果显著。

The development of natural fractures in deep shale gas blocks in sounthern Sichuan Basin varies greatly,and phenomena such as severe fliter loss and inter-well pressure channeling during fracturing are prone to occur,which have a significant impact on the fracture network fracturing effect of shale gas wells.Carrying out the simulation of fracturing fracture network propagation under the influence of natural fractures and optimizing fracture network fracturing parameters according to the characteristics of natural fracture groups in deep shale layers can reduce the adverse effects caused by natural fractures,which is conducive to the improvement of fracturing effects,the reduction of construction risks,and the increase of the ultimate recovery of gas wells.In this study,a fracturing fracture network propagation model under the development of deep shale natural fracture groups was constructed,the diagrams of the optimal design of fracturing in well sections with developed natural fracture groups were drawn and the fracturing parameter optimization design process of well sections with developed fractures was proposed,taking Well LH-7 in southern Sichuan Basin as an example.Through fracturing fluid variable viscosity and displacement fracture network fracturing design,the total fracturing fluid volume of that well increased by 0.75%,the fracture network volume increased by 14%,and the construction efficiency of the fracture network increased by 13%,showing remarkable optimization effects.