Matrix-fracture transfer shape factor for modeling multimechanisitc multicomponent shale gas flow

摘要

Numerical simulation of multimechanisitc multicomponent shale gas flow is computationally intensive and a challenging task. Upscaling of pore scale phenomena to Darcy scale simulations is highly desirable to cut down the computational time. Mass transfer between matrix and fracture in dual-porosity simulators has been traditionally upscaled through a pseudo steady state shape factor, which can be obtained analytically thanks to the linear nature of the pressure diffusion in conventional reservoirs. The use of such a shape factor is well established in modeling of fluid flow and transport in conventional reservoirs. However, the shape factor for multimechanisitc multicomponent shale gas flow is not fully realized and its determination is not straightforward due to the non-linear nature of the governing equations. In this work, we present detailed numerical simulation of multimechanisitc multicomponent shale gas flow to obtain shape factor required for Darcy scale numerical simulation of unconventional reservoirs. It is shown that shape factor can be presented as a function of dimensionless pressure (pseudo pressure), which makes application of transient shape factor independent of time. The dependence of the derived shape factor on pressure drawdown, reservoir temperature, Darcy permeability and fluid composition are also investigated. The theoretical analysis improves our knowledge of shale gas flow dynamics and the results find applications in reservoir simulation of gas production from unconventional reservoirs.