考虑压裂诱导效应的页岩储层工程可压裂性评价

Engineering fracability evaluation of shale reservoirs considering fracturing induced effect

工程可压裂性是页岩气水平井压裂分段选簇的重要评价指标。目前的评价方法通常考虑岩石脆性、断裂韧性以及水平井主应力的影响,忽略了施工参数对可压裂性的影响。在岩石脆性评价基础上,考虑非规则分叉天然裂缝对岩石断裂韧性的影响,引入施工缝内净压力并耦合储层水平应力差构建无因次净压力指数,形成了耦合储层岩石破碎、裂缝延伸和施工参数诱导效应的工程可压裂性评价方法。结果表明:建立的可压性模型评价结果与微地震监测事件数、改造体积具有良好的一致性,表明所建模型可以有效地表征压裂形成复杂缝网的能力。研究成果为页岩水平井分段压裂选择射孔位置提供了依据。

Engineering fracability is an important evaluation index for staged clusters selection of shale gas horizontal well fracturing.Current evaluation methods usually consider the influence of rock brittleness,fracture toughness and horizontal well principal stress,but ignore the influence of operation parameters on fracability.Based on evaluation of rock brittleness,considering the influence of irregular bifurcated natural fractures on rock fracture toughness,dimensionless net pressure index is established by introducing net pressure of operation fracture and coupling horizontal stress difference of reservoir,forming engineering fracability evaluation method that couples reservoir rock fragmentation,fracture extension and induced effect of operation parameters.The results show good consistency of evaluation results by established fracability model with microseismic monitoring events number and stimulated volume,indicating that established model can effectively characterize the capability of fracturing to form complex fracture network.The research provides basis for selection of perforation locations for staged fracturing of shale horizontal wells.