Numerical Study for the Pressure Transient Behavior of Fractured Shale Gas Reservoirs Using a Dual-Mechanism Dual-Porosity Model

摘要

Shale gas reservoirs have become the focus of considerable attention as primary energy resource over the past decades worldwide. Numerical modeling technique plays a critical role in providing the essential tools for evaluating and managing the development of such complex systems. Gas flow in shale formation involves substantial nonlinear complexity. The flow behavior may be governed by the mechanisms of desorption and rock unconsolidation within stimulated natural fracture network. It is very likely that the fracture network is unpropped or weakly propped after hydraulic fracturing. Desorption is also an important mechanism which contributes to the gas production. In this work, a dual-mechanism dual-porosity model was established for pressure transient analysis. Finite-difference method was used for discretizing fluid equations, and Newton method was used to solve the algebraic equations. The typical curves in terms of dimensionless pseudopressure and time were drawn with different sets of parameters. The numerical well-testing model could provide theoretical basis for interpreting production data of shale gas reservoirs.