PRESSURE TRANSIENT ANALYSIS OF FRACTURED HORIZONTAL WELL IN SHALE GAS RESERVOIR

Shale gas reservoirs have received much attention for their potential in satisfying future energy demands. Compared to conventional gas reservoir, Shale gas reservoir is characterized by complicated nonlinear processes, including adsorption and desorption, pressure-dependent permeability and non-Darcy flow. To investigate the e ect of those nonlinear mechanisms, a combined dual-continuum and discrete fracture numerical well test model was developed to analyze the transient pressure. Desorption, pressure-dependent permeability of natural fractures and non-Darcy flow was respectively described by Langmuir isotherm equation, exponential model of permeability and Forchheimer equation. Galerkin finite element method was applied to solve the model. Flow regimes were divided and the e ect of nonlinear factors on pressure response was analyzed according to the well test curve. The results indicate that there are five flow regimes, including fracture linear flow, fracture radial flow, formation linear flow, formation radial flow, pseudo steady state of closed boundary. The shale gas desorption's e ect arising after interporosity flow happened, the bigger Langmuir adsorption volume is, the deeper groove shows on the derivative curve and the later pressure propagate to the border; Bigger pseudo-pressure drop and pseudo-pressure derivative were observed with greater pressure-dependent e ect in the later stage of well test curve; Non-Darcy flow in hydraulic fractures mainly a ecting the early time, the pseudo-pressure drop increased with increasing flow rate. The comparison with analytical solution and field engineering application prove the feasibility of the model.