煤成(层)气资源综合开发中的合层压裂可行性评价

针对临兴—神府示范区煤(成)层气资源纵向上岩性叠置、多层系交互赋存、薄层/夹层发育的地质赋存特征,及薄互层、接触或邻近产层间单层压裂可改造性差的技术难题,提出了适用于煤成(层)气资源综合开发的合层压裂工艺理念。采用数值模拟方法,通过分析产层间界面胶结强度、界面倾角、层间应力差、压裂施工排量等因素对合层压裂裂缝扩展的影响,优化了压裂施工参数,优选了适宜于合层压裂工艺的储层条件,并基于岩石破裂和界面断裂准则,综合考虑煤体结构、界面力学与储层应力场等因素,建立了煤成(层)气储层合层压裂可行性的多级评价模型。

Feasibility evaluation of commingle fracturing in the integrated development of coal-derived gas resources

The geological characteristics of coal-derived gas resources in Linxing and Shenfu area show a multi-layer system vertically,a superposition and mutual occurrence of lithology,as well as the development of thin interlayers and a low effective rate by monolayer fracturing within these thin interlayers or directly/closely-contact layers.A multilayer fracturing technology for exploring and developing the coal-derived gas resources was introduced in this paper.By numerical simulation method,the paper studied the influences of cementation strength and dip angle of interface,stress difference between layers,fracturing operation displacement and other factors on fracture propagation.Also,the fracturing operation parameters were optimized,then a suitable reservoir conditions for multilayer fracturing was determined.Based on rock crack criterion and interface fracture criterion,a multilevel evaluation model of multilayer fracturing feasibility in coal-derived gas reservoir was finally established,with factors like coal structure,interface mechanics and stress field taken into account.The study has a certain guiding significance to the application of the multilayer fracturing technology.