Accounting for Remaining Injected Fracturing Fluid

The technology of multi-stage fracturing of horizontal wells made the development of shale gas reservoirs become greatly successful during the past decades. A large amount of fracturing fluid, usually from 53,000 bbls to 81,400 bbls, is injected into the reservoir to create the fractures. However, only a small fraction of injected fracturing fluid from 10% to 40% has been recovered during the flowback process and the long term shale gas well production period. Possible mechanisms for low load recovery include ineffective dewatering of the propped fractures, matrix pore scale water retention related to imbibition, capillary fluid retention, relative permeability, and water held up in a fracture network (complexity) opened or reopened during fracture treatments. This work is critical both to understand existing shale gas well performance and to improve shale gas well designs. Current treatment practices that promote fracture complexity as an objective may be misplaced in some shale formations. As well, the number of fractures seemingly created from so many perforation clusters per fracture stage may be undermining the ability to dewater created fractures. The insights derived from this research reveal important differences in load recovery behavior that may impact well performance in different shale formations and highlight how effectively the wells are draining the stimulated shale volume