Characterization and evaluation of hydraulic fracture (HF) attributes in aquifers and formations are one of the most important tasks for hydrogeologiests and engineers. However, the complexity in multiphase flow and exclusion of HF closure by the current methods restricts the accuracy of fracture characterization. This study presents a new type-curve method to characterize hydraulic fracture (HF) properties and dynamics from fractured-rock aquifer or reservoir during fracturing fluid flowback, which contains mostly water. The proposed method includes a semianalytical model, as well as a workflow to estimate HF properties (i.e., initial fracture pore-volume and fracture permeability) and HF closure dynamics (through iterating fracture compressibility and permeability modulus). The semianalytical model considers the coupled two-phase flow in the fracture and matrix system, the variable production rate at the well, as well as the pressure-dependent reservoir and fluid properties. By incorporating the contribution of fluid influx from matrix into the effective fracture compressibility, a new set of dimensionless groups is defined to obtain a dimensionless solution for type-curve analysis. For the first time, a family of type curves is reduced to only one curve for flowback analysis, significantly improving the matching procedure’s uniqueness. 
The accuracy of the proposed method is tested using the synthetic data generated from six numerical simulation cases for the flowback period of fracturing fluids in the formation. The numerical validation confirms the unique behavior of type curves during fracture boundary-dominated flow and verifies the accuracy of the type-curve analysis in the characterization of fracture properties. For field application, the proposed method is applied to two multi-fractured horizontal wells (MFHWs) in Marcellus and Eagle Ford shale reservoir. The agreement of interpreted results between the proposed method and straight-line analysis not only demonstrates the practicality in field application but also illustrates the superiority of the type-curve method as an easy-to-use technique to analyze flowback fluids data, since the type curve combines flow regime identification and fracture properties extraction into a two-in-one plot. The analysis results from both of the field examples reveal the consistency in the estimated fracture properties between the proposed method and long-term history matching.

Fengyuan Zhang is an assistant professor of petroleum and natural gas engineering at China University of Petroleum, Beijing. He specializes in pressure and rate transient analysis of water flowback and long-term production data in hydrocarbon formations. His current research interests include analytical and numerical modeling for rate transient analysis and production data analysis, multiphase flow and transport in porous media, unconventional reservoir modeling, hydraulic fracturing evaluation, and carbon dioxide sequestration in geological formations. Fengyuan has authored and co-authored more than 15 technical publications. He received the 2021 Outstanding Young Faculty, the 2019 SPE Nico van Wingen Memorial Graduate Fellowship and the 2019 SME WAAIME Scholarship. He holds Ph.D. degree in petroleum and natural gas engineering from The Pennsylvania State University, University Park, bachelor’s and master’s degrees in petroleum engineering from China University of Petroleum, Beijing.