Successful Application of Capacitance Resistance Modeling to Understand Reservoir Dynamics in Brown Field Waterflood – A Niger Delta Swamp Field Case Study

Abstract

Capacitance Resistance Model (CRM) is an analytical tool for estimating reservoir properties and connectivity between producer-injector pairs in an established waterflooded oil reservoir system. The analysis incorporates historical production data, injection rates and available bottom hole pressures. In Swamp Field B (Niger Delta Nigeria), there were concerns of connectivity between producer and injector pairs in the K2 reservoir. CRM analysis was applied to resolve the uncertainty in producer-injector connectivity and provide better understanding of the reservoir flow dynamics. Understanding the connectivity between existing injectors and producers, to ensure adequate water injection distribution for reservoir voidage balance and pressure maintenance necessitated a geologic and engineering review of existing data. The results of the study revealed strong inter-well connectivity between active producers and two idle injectors in the reservoir for the period analyzed, corroborating a revised geologic interpretation of the reservoir. The idle injectors were previously left shut-in due to a geologic interpretation of the presence of shale impacting connectivity and performance. Upon implementing recommendations from the study, an immediate pressure and production response was observed within three months of restoring the two idle injectors. The reactivation of the idle injectors also resulted in $20 MM savings by averting further work on a proposed new water injector. This paper discusses the application of CRM in understanding producer-injector connectivity and emphasizes the use of digital analytic tools to better understand waterflood performance and address challenges with balancing voidage and maintaining reservoir pressure. It demonstrates the value of CRM technique in brown fields and the multidisciplinary approach adopted. Further application of similar techniques in other waterflood reservoirs within Chevron Nigeria is currently ongoing.