Integrated Field Optimization Strategy Applied to an Offshore Water Injection Project

Abstract

Abstract Some of the most significant challenges faced with respect to the management of offshore water injection projects are associated with maintaining injectivity into the reservoir and with handling H2S produced due to reservoir souring. This paper presents the process followed and findings generated by a comprehensive review of a mature water injection project performed with the goal of delivering a coordinated operating strategy that would maximize the life of field revenues associated with water injection. An integrated and comprehensive field optimization approach to maximize the whole-life value of the total asset was undertaken. Aspects covered included water injection system operating practices, mechanical design and integrity management of the injection system, the chemical treatment program followed for both the injection and production streams, and reservoir modeling and production management. Recommendations resulting from this review were prioritized based on their impact on the whole-life performance of the asset, rather than the more common practice of separating the injection and production system reviews or the assessments of reservoir management and facility operation. Areas of particular benefit were identified in association with implementation of an active souring control strategy to reduce future risks to the production system metallurgy by sulfide stress cracking (SSC), a focus on integrity management of the water injection system to maximize long-term system availability, and the implementation of an inter-well water tracer injection program to enable the validation of current reservoir models and support the placement of future injectors and producers. The combined approach employed in this review has enabled the Operator to adopt an operating strategy for the facility that will optimize operating costs and revenues through the remaining life of the asset. In addition to gains in future injection system uptime and the immediate optimization of the chemical treatment program, this review has also provided a basis to guide the evaluation of future reservoir management and field development strategies.