“工厂化”压裂多裂缝应力干扰与延伸规律研究

Research on stress interference and propagation law of multi-fracture for"factory"fracturing

水平井分段多簇体积压裂是实现致密油资源商业化开发的重要手段。文中基于位移不连续法,建立水平井分段压裂多井、多裂缝扩展计算模型,开发数值模拟软件,研究单井多簇压裂和多井工厂化压裂时的裂缝延伸规律。结果表明:多裂缝同步扩展时,受应力阴影效应影响,裂缝周围地应力发生改变,段内各裂缝间压裂液流量分配不均,裂缝发生不均匀扩展现象;合理布置压裂簇的数量与位置,可促进裂缝均匀扩展;多井平行压裂和交错压裂时,井间形成拉应力集中区,压裂段中部裂缝相互靠近,平行压裂裂缝易导通,交错压裂裂缝则易出现“雁型裂纹”;对于平行压裂和交错压裂,同步压裂裂缝延伸均匀性更强,压裂效果更好。该研究成果可为致密油储层工厂化压裂施工设计提供参考。

Staged multi-cluster volume fracturing for horizontal well is an important method to realize commercial development of tight oil reservoirs.Based on the displacement discontinuity method,the calculation model of multi-well and multi-fracture propagation for horizontal well staged fracturing was established,and the corresponding numerical simulation software was developed to study the fracture extension law of single well multi-cluster fracturing and multi-well"factory"fracturing.The results show that the simultaneous propagation of multiple-fracture is affected by the stress shadow effect.The in-situ stress around the fractures would be changed,and the flow distribution of fracturing fluid between fractures within segment is uneven,which lead to the uneven propagation of fractures.Reasonable arrangement of the number and location of perforation clusters can promote the uneven propagation of fractures.For multi-well parallel fracturing and zipper fracturing,the tensile stress concentration zone is formed between wells,and the fractures get close to each other in the middle of the fracturing segment.Fractures are easy to connect for parallel fracturing,and"goose crack"are prone to be formed for zipper fracturing.For parallel fracturing and zipper fracturing,the uniformity of fracture extension is stronger and the fracturing effect is better for simultaneous fracturing.The research results can provide reference for"factory"fracturing design of tight oil reserviors.