复杂人工裂缝产状页岩气藏多段压裂水平井产能评价

Productivity evaluation of multi-stage fracturing horizontal wells in shale gas reservoir with complex artificial fracture occurrence

基于页岩气多重运移机制理论,针对页岩储层压裂裂缝呈现复杂形状和非均匀分布的实际情况,建立耦合了两类孔隙表观渗透率的页岩表观渗透率统一模型,另外,运用实空间源汇函数理论和压降叠加原理,建立了气藏—裂缝—井筒耦合渗流模型。模拟分析了页岩气微观渗流、裂缝形状和裂缝非均匀分布对产能的影响,结果表明:微观渗流对页岩气井产量的影响不可忽视,在生产初期考虑微观渗流的日产气量比不考虑微观渗流的日产气量高了20.3%;复杂形状裂缝的产能比理想矩形裂缝的产能要低,其中星形裂缝的产能最低;裂缝的非均匀分布会影响水平井的产能,需选择最优布缝方式。研究模型综合考虑了页岩气的微观渗流机理和实际压裂裂缝情况,为页岩气藏压裂水平井产能研究提供了参考。

Considering complex shape and non-uniform distribution of fracturing fractures in shale reservoir,on the basis of multiple migration mechanisms a unified apparent permeability model is developed,incorporating two types of pore apparent permeability based on multiple migration mechanisms.This model serves as the foundation for establishing a gas reservoir fracture-wellbore coupled seepage model,utilizing real space source function theory and pressure drawdown superposition principle.Through simulations and analyses,the study investigates the effects of micro seepage,fracture shape and non-uniform distribution of fractures on shale gas productivity.The demonstrate that micro seepage significantly impacts shale gas well production,with daily gas production being 20.3%higher when considering micro seepage during the initial stage compared to neglecting it.Furthermore,the productivity of wells with complex fractures is lower than that of wells with ideal rectangular fractures,and star-shaped fractures exhibit the lowest productivity.The non-uniform distribution of fractures also affects the productivity of horizontal wells,and an optimal fracture layout is identified.The model takes into account both the micro seepage mechanism and actual fracturing fracture of shale gas,providing valuable guidance for the productivity research of fractured horizontal wells in shale gas reservoir.