4 - Fluid flow law in fracture-vug carbonate reservoir

Abstract

Complex reservoir space and different-scale flow channels in the fracture-vug carbonate reservoir result in complex flow law and flow mechanism, involving one-dimensional (1D) pipe flow, 2D flow on the fracture surface, 3D flow in unfilled (or semi-filled) vugs and caves, and other flow patterns among vugs, caves, fractures, and matrix. Understanding the fluid flow law in a fracture-vug reservoir and those among different media is the basis for the scientific development of the fracture-vug reservoir. According to the characteristics of the fracture-vug reservoir, the physical modeling similarity criterion group has been established, multitype typical fracture-vug models have been built, macrophysical simulation experiment devices for fracture-vug media have been designed, and physical simulation experiments and research for fluid flow mechanisms have been carried out systematically. The systematical experiment of one-phase flow has demonstrated the one-phase flow features and the transformation conditions in the reservoir space in different types of fracture-vug reservoir, based on which one-phase flow equations have been established. The systematical oil–water two-phase flow experiment has determined the two-phase flow features and relative permeability curves, and accordingly two-phase flow patterns, based on which two-phase flow equations have been developed. In addition, the interporosity flow law among different types of reservoir has been revealed, which provides the foundation for the development of the numerical simulation technology.