Use Capacitance-Resistance Model to Characterize Water Flooding in A Tight Oil Reservoir

Abstract

Gaither Draw Unit is a heterogeneous and tight formation with an average permeability of 0.1 mD. After more than 1.7 MMSTB water has been injected, there was no clear signal indicating the injected water from any producer. However, knowing the distribution of injected water is critical for future well planning and quantifying the efficiency of injection. The objective of this study is to show how the Capacitance-Resistance Model (CRM) was used to study this field and how the results were validated using traditional reservoir simulation. The CRM model quantitatively describes the connectivity and the degree of fluid storage between injectors and producers only from injection and production rate data. On the basis of material balance, signals from injectors to producers can be represented in the CRM model. The connectivity between each injector/producer pair of a selected portion of the field is estimated by using a constrained nonlinear multivariable optimization technique. The fitting results of the connectivity and the time constant through the CRM analysis indicate the regional permeability heterogeneity, which is consistent with Computer Modelling Group, Ltd. (CMG) full field modelling. The time constants conform to the low permeability of a tight formation. The history matched CMG full field model and results from the CRM analysis both present similar pressure distributions. It indicates that the majority of the injected water mainly saturates the regions surrounding the injectors, and the low transmissibility prevents pressure dissipation.