Flow Modeling of Well Test Analysis for Porous-Vuggy Carbonate Reservoirs

Porous-vuggy carbonate reservoirs consist of both matrix and vug systems. This paper represents the first study of flow issues within a porous-vuggy carbonate reservoir that does not introduce a fracture system. The physical properties of matrix and vug systems are quite different in that vugs are dispersed throughout a reservoir. Assuming spherical vugs, symmetrically distributed pressure, centrifugal flow of fluids and considering media that is directly connected with wellbore as the matrix system, we established and solved a model of well testing and rate decline analysis for porous-vuggy carbonate reservoirs, which consists of a dual porosity flow behavior. Standard log-log type curves are drawn up by numerical simulation and the characteristics of type curves are analyzed thoroughly. Numerical simulations showed that concave type curves are dominated by interporosity flow factor, external boundary conditions, and are the typical response of porous-vuggy carbonate reservoirs. Field data interpretation from Tahe oilfield of China were successfully made and some useful reservoir parameters (e. g., permeability and interporosity flow factor) are obtained from well test interpretation.