宁209X1立体开发平台水力压裂复杂裂缝井间干扰机理

Inter-well Interference Mechanism of Complex Hydraulic Fractures on Ning209X1 Cube Development Platform

四川盆地长宁区块页岩气储层已经进入立体开发阶段,在龙马溪组主力产层采用“W”形的上下两套水平井进行立体开发,井距由最初的500 m减小到300 m。随着井距的减小和立体开发井位的部署,井间裂缝产生干扰时常发生,甚至造成井间压窜,致使邻井产能下降。为探究立体布井水力压裂复杂裂缝井间干扰机理,基于地质工程一体化思路,建立了宁209X1立体布井平台的综合地质构造及地质力学模型、天然裂缝的离散裂缝网络模型以及立体井组水力压裂复杂裂缝扩展数值模型,模拟了该平台4口井的压裂裂缝形态,并对井间压裂裂缝干扰机理进行分析。结果表明:该平台水力压裂裂缝在横向上难以对邻井产生干扰,且缝高方向扩展受控;少数压裂段各簇裂缝出现了非均匀起裂扩展现象,部分压裂段出现非对称扩展现象;在当前条件下,天然裂缝带是决定是否产生井间干扰的关键性因素。研究结果可为裂缝性页岩气立体开发平台压裂施工参数优化提供理论支撑。

The shale gas reservoir in Changning Block of Sichuan Basin has entered the stage of three-dimensional development.The main production layer of Longmaxi Formation adopts the“W”shaped upper and lower horizontal wells for three-dimensional development,and the well spacing was reduced from the initial 500 m to 300 m.With the reduction of well spacing and the deployment of three-dimensional development well locations,the interference caused by cross well fractures often occurs and even causes cross well pressure channeling,resulting in the decline of adjacent well productivity.In order to explore the interwell interference mechanism of complex fractures in cube development wells.The idea of geological-engineering integration was considered,the comprehensive geological structure and geomechanics model of the Ning209X1 cube development platform,the discrete fracture network model of natural fractures,and the three-dimensional numerical model of complex fracture propagation in hydraulic fracturing were established.The fracture morphology of the four wells in Ning209X1 platform were simulated.And the inter well fracture interference mechanism was analyzed.The results show that the hydraulic fracturing fracture of the platform is difficult to interfere with the adjacent wells in the transverse direction,and the fractures are difficult to propagate through layers in vertical direction.In a few fracturing sections,the clusters of fractures appear uneven initiation and propagation,while in some fracturing sections,asymmetric propagation occurs.Under the current conditions,the distribution of natural fractures is the key factor to determine whether there is interwell interference.The research results can provide theoretical support for the optimization of fracturing operation parameters of fractured shale gas cube development platform.