Cluster Spacing Effect on the Fracture Interference Including Stress Shadow

Abstract

Abstract Over the last decade, the application of horizontal drilling and multistage hydraulic fracturing has significantly impacted shale formations, achieving economic productivity through the creation of expansive fracture surfaces. Determining the optimal cluster spacing in shale gas wells is a complex task, contingent upon the unique geological characteristics of each formation. While a closer spacing between clusters can enhance gas recovery, it escalates drilling and completion costs, compounded by stress shadow effects on fracture propagation. This research introduces a comprehensive workflow to investigate the impact of cluster interference on well performance. Commencing with a fracture propagation model, accounting for stress shadow effects due to the same injected slurry volume, we integrated analytical rate transient analysis (RTA) with reservoir numerical simulation to assess the effective fracture surface area for hydrocarbon production. The effective fracture surface area from RTA to the actual stimulated fracture area from numerical simulation ratio was then correlated to cluster spacing. Findings reveal that higher stage numbers and tighter cluster spacing result in increased cluster interference, yielding a low effective to actual fracture surface area ratio and heightened stress shadow effects, hindering fracture propagation. Conversely, widening cluster spacing, with a constant injected proppant volume, boosts the effective to actual fracture surface area ratio and diminishes cluster interference. Optimal spacing, based on formation properties, was identified as 6 clusters per stage with 33 ft spacing. This research provides valuable insights for completion and reservoir engineers, aiding in the optimization of cluster spacing to maximize well revenue.