Multi-Stage Hydraulically Fractured Shale Gas Rate Transient Analysis

Abstract The common completion technique in horizontal shale gas wells is by hydraulically fracturing in multi-stages. In this paper, a linear dual porosity model is used to approximate the shale gas completions with a horizontal well and multiple hydraulic fractures. Five flow regions are identified with this model. Region 1 is transient drainage in the fractures, Region 2 is simulataneous drainage from matrix and fractures or bilinear flow, Region 3 is the infinite-acting case, Region 4 is transient drainage from the matrix and Region 5 is the boundary-dominated flow case. Derived equations are presented for each of the flow regions. It appears that field production data exhibit Region 4. This transient flow regime is the only flow regime available for analysis in many wells. A skin effect for Region 4 is observed in many wells and described in this paper. A procedure is presented in this paper to analyze field data and is illustrated with a sample case..