A composite model to analyze the decline performance of a multiple fractured horizontal well in shale reservoirs

In this work, we present a composite model that considers the effect of gas desorption to describe the fluid flow performance of a hydraulic multistage fractured horizontal (MFH) well with stimulated reservoir volume (SRV) in shale. Based on the Langmuir adsorption isotherm, Fick's law and dualporosity idealization, this MFH well model for shale gas reservoirs is tailored to our problem conditions and solved using discrete numerical methods. Then, Stehfest's numerical algorithm and the Gauss elimination method are used to obtain production decline and pressure transient type curves. The main flow regimes of shale gas MFH wells are identified with the following characteristics: wellbore storage, linear flow in the SRV region, diffusion flow and later pseudo-radial flow periods. Sensitivity analyses show that the transition flow regime and the production performance of an MFH well in shale are mainly affected by the Langmuir volume, radius and permeability of the SRV region. This study provides some insights into the mechanisms of shale gas flow and assists in understanding the production decline dynamics in shale reservoirs. (C) 2015 Elsevier B.V. All rights reserved.