Successful Story in Offshore EOR Full Field Development (Shengli - CB22F), Production Increase, Energy Savings!
Authors: Rotier D. , Gong J. , Li B. , Chen L. , Dupuis G. , Cognet M. , Tizzotti M. , Zhu C. , Gathier F. , Ruiz M. 
Published: September 2024

This paper presents the implementation of chemical enhanced oil recovery (CEOR) on the offshore platform CB22F, detailing its impact over three years and proposing improvements for future deployments. It discusses the project's effects, such as increased oil production, reduced water cut, and lowered CO2 emissions, while sharing insights for optimizing future CEOR designs on two newly sanctioned platforms. The CEOR strategy on CB22F has shown significant outcomes, demonstrated by an increase in oil production, a reduction in water cut, and a decrease in CO2 emissions.

Oil production increased by 663 of barrels per day (b/d), the water cut decreased from 90% to 80.5%, reducing the volumes of water handled. This decrease in water cut lowered energy consumption for water pumping and chemical treatment costs for produced water, leading to a reduction in cost and CO2 emissions to produce one barrel of oil. The test area began showing positive effects by June 2021, with a significant decrease in water content in produced fluids in 2022 and a rapid increase in oil output. By the end of March 2024, the water cut stabilized around 80.5%, and the cumulative oil increase from the 44 effective production wells reached 3,800,000 barrels, corresponding to a 4.27% increase in oil recovery. This cumulative increase translates to 28.9 tons of oil per ton of polymer injected, indicating the project's economic viability.

Building on the success of CB22F, CEOR will be implemented on two newly sanctioned platforms with designs incorporating improvements learned from CB22F's experience. Bulk polymer delivery via pneumatic transfer will mitigate hoisting risks, improve occupational health, increase offshore storage capacity, and reduce delivery rotations, thus decreasing CO2 emissions associated with logistic operations. An integrated injection system will involve a centralized polymer injection system on the main platform, facilitating efficient distribution to both main and satellite platforms. The introduction of new Conical Pressure Reducer (CPR) skids, equipped with low shear valves, will regulate injection pressure, and adapt the polymer concentration for individual wells, minimizing polymer degradation and footprint compared to conventional methods.

To address higher polymer/surfactant concentrations in produced fluids, concerns regarding emulsification are being managed through the development of new, high-efficiency water clarifiers. These improvements, guided by CB22F's experience, are expected to further optimize CEOR performance and efficiency on future platforms.

This paper provides insights for engineers by demonstrating a successful CEOR implementation with concrete results and data, sharing practical improvements for future CEOR designs on offshore platforms, addressing potential challenges, and proposing viable solutions. Additionally, it contributes to knowledge on CO2 reduction strategies in oil and gas production, highlighting the environmental benefits alongside the financial gains. The reduction in CO2 emissions per barrel of oil produced underscores the broader impact of the project beyond immediate financial gains, contributing to the long-term sustainability of oil production operations.