Invalidating Water Injection Discontinuation Plan Through Comprehensive Surveillance Data Acquisition and Interpretation

Abstract Waterflooding technology has been a longstanding practice in the oil and gas industry, with its roots dating back to its development in the US in the 1940s. The fundamental concept involves replenishing drained spaces to maintain system pressure, although the complexity arises in reservoirs filled with heterogeneities. Beyond pressure preservation, waterflooding also enhances production through efficient sweeping. The success of waterflooding hinges on the dual metrics of pressure maintenance and production rate. However, quantifying this success is not always straightforward and can be obscured by the poor performance of individual producers. This paper presents a real case study conducted at Field S, highlighting a meticulous evaluation of the impact of water injection. Despite the drilling of two peripheral water injectors in 2021, water breakthrough shortly after injection initiation led to a nearly 20% reduction in field production. Analysis of available data pointed to injection-induced fractures, inadequate cement behind casing channeling, and high permeability contrast in multiple sand lobes as potential sources of increased water cut observed in key wells. To address this, an intermittent flow strategy was implemented at the expense of the voidage replacement ratio (VRR), allowing the gas oil ratio (GOR) to develop and improve well lifting. Various diagnostics, including streamline analysis, injection fall-off, advanced well interference tests, and capacitance-resistant model analysis, were assessed. Field S, following its field development plan, plans to add 52 infill wells within the next 5 years to its existing inventory of 15 wells. Reservoir simulation work has been endorsed to support continuous water injection for pressure maintenance before infill, aligning with the planned recovery factor. The robustness of the water injection program faced a challenge when management proposed its discontinuation after only 30 months of injection. This paper showcases a real case study demonstrating the utilization of multiple surveillance tools and diagnostic plots to validate waterflood efficiency, enabling Field S to persist with its water injection program. The paper provides a comprehensive analysis of how a tailored surveillance program and data interpretation workflows could enable petroleum engineers to proactively diagnose and troubleshoot water injection programs more efficiently with minimal intervention. Additionally, it demonstrates the application of various water injection-related diagnostic plots from published papers on the Field S dataset and their compatibility index.