Abstract
The efficient development of shale reservoirs relies on multi-stage hydraulic fracturing technology in horizontal wells involving the difficulty of multi-scale flow for either gas or water phases, which is characterized by the changes in the stress and temperature fields. The original simulation methods are unable to accurately solve the multi-physics field-coupled problems under such complex mechanical conditions or have low stability for two-phase gas-water problems. For this purpose, this study conducted the shale gas production simulation by the meshless finite difference method (GFDM) for the first time to ensure the stability and accuracy of calculations. Bases on the previous multi-sector coupled physical model for shale gas development and proposes a coupled thermo-hydro-mechanical multi-physical field mathematical model considering two-phase gas-water flow. The model is postulated based on different sectors considering various characteristics of gas/water flow, namely desorption attributes, deformation degree and heat transfer characteristics. This method was used to calculate the variation of the multi-physical field and compare the properties of gas-water flow within different reservoir conditions without any non-convergence situation during the calculation. The simulation results indicate that the stress field has a crucial effect on the yield, such that discard of its coupling causes the yield to be overestimated by 12.5%. In contrast, the temperature field has a marginal effect (less than 1%) and can be neglected according to the operating conditions. Furthermore, the stress field significantly characterizes the micro-fracture sector, which is also the major flow-contributor, such that the yield is overestimated by 11% in absence of its coupling, while the effect of stress field in the matrix sector is lower than 1%.
Published Version
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