Injection/Falloff Testing in Heterogeneous Reservoirs

Abstract

In this work, we present a new theoretical understanding of pressure data obtained at a water injection well. The theory provides new physical insight into how permeability heterogeneity, saturation gradients, and mechanical skin factor combine to influence the pressure response at the well. Based on the theoretical equations, methods for analyzing injection/falloff pressure data in both homogeneous and radially heterogeneous reservoirs are presented. For homogeneous reservoirs, we present procedures for estimating the mechanical skin factor from injection or falloff pressure data. Our theory provides a procedure for analyzing the pressure response during the second injection period of a two-rate test. It is shown that the information that can be obtained from a two-rate test is similar to that obtained from a falloff test.