MULTISCALE AND MULTIPHASE MODELING OF FLOW BEHAVIOR IN DISCRETE FRACTURE NETWORKS FOR TIGHT OIL RESERVOIRS

Fluid transport in tight reservoirs is obviously a multiscale behavior. The fluid occurrence status and flow mechanisms are different in different scales of porous media and their characterization and coupled simulation are complex processes. This study presents a numerical investigation of pressure and flow transient analysis of oil production from a horizontal, network-fracturing well in tight oil reservoirs. A specialized three-dimensional, three-phase discrete multimedia numerical simulator which incorporates known non-Darcy behavior in tight oil reservoirs was developed and used for this purpose. First, we discuss a multi percolation mechanism, multimedia concepts of different scales for handling microscopic and macroscopic heterogeneity of tight reservoirs after network fracturing. By using the discrete modeling method, we describe and characterize different scale pores, discrete natural fractures with different scales, and discrete artificial fractures. The flow simulation in different scale mediums is carried out by the self-recognition method of the percolation mechanisms. Then sensitivity studies of flow rate are presented with respect to different pore-size distribution under the same porosity condition. Different sizes of pore distribution patterns have obvious differences in oil production, which indicates that the characterization of different scale percolation media is crucial to unconventional tight oil. Specifically, we will analyze a field example from Changqing tight oil to demonstrate the use of results and methodology of this study.