Investigation of Flow Model and Flow Behavior in Typical Fractured-Vuggy Structure of Carbonate Reservoirs

The storage space and pore structure of fractured-vuggy carbonate reservoirs are complicated. This paper analyzed the flow model for different storage spaces in such reservoir, and proposed the model of free and porous media coupled flow, which is a transition flow pattern between free flow and Darcy flow. The applied flow model for simulation study was the corrected Brinkman equation. Based on the CT scanning images of cores obtained from Tahe Oilfield, we constructed the 3-D digital core and then extracted the distinct factured-vuggy structures. The COMSOL Multiphysics software was employed to simulate pressure field, velocity field, and streamline of single-phase flow in fracture-vuggy area under different differential pressures. Applying three different flow models, we investigated the fluid flow behaviors of free flow, Darcy flow, and free and porous media coupled flow, respectively.