NUMERICAL SIMULATION OF THE EFFECTS OF RESERVOIR HETEROGENEITY, FRACTURES, AND MULTI-WELL INTERFERENCE ON PRESSURE TRANSIENT RESPONSES USING MULTISTENCILS FAST MARCHING METHOD

Abstract

Analysis of rate and pressure transient responses of a well in spatially heterogeneous reservoir cannot be performed using conventional well-test analytical equations. An accurate analysis of transient pressure/rate responses of wells in heterogeneous naturally fractured reservoirs requires precise characterization of the complex interactions between various reservoir and well features. These features include heterogeneity, natural and induced fractures, reservoir boundaries, and well interference. Single-stencil fast marching (SFM) method has been used for pressure transient analysis (PTA) and history matching in heterogeneous reservoirs. As an improvement to the SFM method, we develop and test the multistencils fast marching (MFM) method, which exhibits one order of magnitude higher accuracy compared to SFM method. We extensively validate the MFM method for various reservoir and wellbore scenarios by comparing its predictions against those of SFM Method, KAPPA Saphir analytical model, and KAPPA Rubis numerical model. MFM method can be effectively used to estimate pressure response not only in homogeneous reservoir with heteromorphous geometry of no-flow boundary but also in highly heterogeneous reservoir affected by high contrast permeability/porosity distribution and in the presence of induced/natural fractures or impermeable zones. Furthermore, using embedded fracture multistencils fast marching (EFMFM) method, we improve MFM method to model a discrete fracture on the cartesian reservoir girds. Through EFMFM method, pressure response data can be estimated accurately not only in a computationally efficient way, but also in an intuitive way with the visualization of the time-varying drainage volume.