Multiphase transient analysis of flowback and early production data ofunconventional gas wells

Analysis of fracturing water flowback data from hydraulic fractures in unconventional reservoirs playsan important role in determining key fracture properties and predicting future well performance. Currentflowback data analysis tools mostly rely on empirical correlations and/or simplified models. This paperpresents a semi-analytical, multiphase solution that is applicable to the analysis of not only water flowbackbut early gas production data of multi-fractured horizontal gas wells. The proposed solution couples aGreen's function-based analytical solution for gas flow in matrix with a finite-difference numerical solutionfor two-phase (gas and water) flow in fracture domain. The validity of proposed semi-analytical solutionis verified against simulation results generated using commercial numerical simulators. Inverse analysistechniques are developed based on the proposed semi-analytical solution and presented in the form of typecurves. Synthetic case studies show that the proposed type-curve methods can provide explicit and accurateestimation of fracture and reservoir properties, including fracture conductivity, and fracture pore volume.For all case tested, the proposed model is shown to provide accurate and consistent prediction of reservoirperformance and estimations of fracture properties while maintaining the simplicity of explicit, iteration-free calculations.