Cluster Spacing Optimization for Horizontal-Well Fracturing in Shale GasReservoirs: Modeling and Field Application

摘要

Multi-stage fracturing in horizontal well is the core technology for commercial exploitation of shale gasreservoir,in which the cluster spacing plays an important role to impact the fracturing performance-undersized cluster spacing might make the stimulated reservoir volume(SRV),activated by differenthydraulic fractures,excessively overlap with each other,while oversized cluster spacing might leaveunstimulated regions between neighboring hydraulic fractures; in either case the fracturing would beinefficient.However,most current cluster spacing design methods are imperfect without a reliable SRVestimation model.This paper established a numerical model to estimate the SRV by simulating fourkey processes during multi-stage fracturing-hydraulic fractures propagation,formation stress changing,reservoir pressure lifting,and natural fractures failure.Then,based on this SRV model,an optimizationmethod for cluster spacing was proposed and applied in Fuling shale gas field in Southwest China.Weanalyzed the influence of geological conditions and fracturing parameters on the optimal cluster spacing,anddrew the reference charts for cluster spacing design in Fuling gas field.This research developed an effectivecluster spacing optimization method,reduced the uncertainty in cluster spacing design,and provided somenew insights on the optimal design of multi-stage fracturing in horizontal shale gas well.