A Quantitative Evaluation Method for Inter-well Fracture Communication Strength of Multifractured Horizontal Wells from Two-Phase Shale Gas Reservoirs: Field Cases Study

Abstract The reduction in well spacing for multi-fractured horizontal wells in shale gas reservoirs increases the risk of fracture communication. Fracture hits and induced fracture communication between parent and child wells can significantly reduce the gas production of the parent well. The current models are unable to quantify the communication strength of inter-well hydraulic fracture and inter-well induced fracture simultaneously. This work develops a practical semi-analytical model for the quantification of inter-well fracture communication strength by analyzing two-phase production data from the parent-child well system. We define the hydraulic fracture hit region (FHR) and enhanced fractured hit region (EFHR) to establish the relationship between inter-well fractures. The model simplifies the system based on the compartment concept, dividing the flow region into the primary hydraulic fracture (PHF), enhanced fractured region (EFR), fracture communication region and induced fracture communication region. A set of differential equations is solved using multi-region material balance equations with adaptive time-stepping to obtain the changes in pressure and saturation within the drainage area to calculate shale gas production. The results show that the production of the parent well undergoes a transient decline after the communication of the hydraulic fracture. Once the induced fracture commences communication, the rate of decline in parent well production exceeds the natural decline. A comparison with numerical simulation results validates the accuracy of the new method. Subsequently, this method is applied to a shale gas well platform in the Sichuan region of China. History matching of single-well production data can explain parameters such as fracture half-length, reservoir water saturation, matrix permeability, length and permeability of hydraulic fracture hits region, permeability of EFHR and the volume of the connected region, with higher computational efficiency than numerical simulation. A new quantitative evaluation method for inter-well fracture communicating strength of multi-fractured horizontal well is proposed. This model can simultaneously quantify the communication strength of inter-well hydraulic fracture and inter-well induced fracture, and provide guidance for evaluating the effectiveness of the reservoir fracturing effect.