Carbon Dioxide (CO2) injection is a common process used to increase hydrocarbon production in oil and gas fields, which is known as the enhanced oil recovery (EOR) process. This paper presents modeling of a carbon capture, utilization and storage (CCUS) project using an integrated operation and optimization approach.

In this case study, the subsurface system consists of two different reservoirs, a gas condensate and an oil reservoir. The products from the two reservoirs are processed in a single surface processing facility. The CO2 will be captured from both reservoirs and injected into the oil reservoir after being processed in the surface facility. The CO2 from various capture processes will produce different types of residual components, and the effects of different compositions of the injected CO2 stream on field economic revenue will be studied. The verification of extra cost by increasing the CO2 mole fraction in the recycle system is modeled in the economic cost equation. The final surface separation products will be condensate (oil), natural gas liquid (NGL), and sales gas.

Various derivative-free optimization methods will be used to maximize the net present value (NPV) of the CO2 EOR project. The decision variables are the multi-stage separator pressure conditions (surface parameters) and the CO2 injection rate (sub-surface parameter). Optimization results using different optimization methods will be compared to determine the best field operating parameters. The possibility of combination with water injection will also be investigated to determine the best injection scenarios.

An integrated analysis of the CO2 injection process provides a thorough and comprehensive understanding of the performance of the complete CO2 injection value chain. Optimization at the field scale provides insights into the subsurface response to field scale parameter variations. The integrated approach presented in this paper will provide a basis to evaluate CO2 EOR scenarios compared to other injection strategies, such as surfactant or polymer injections.

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