CO2 sequestration through enhanced oil recovery in a mature oil field

Recent advances in enhanced oil recovery (EOR) technology create new opportunities for CO₂ sequestration. This paper proposes a technical–economic model for underground storage of CO₂ emitted by a fertilizer industry in the Northeast of Brazil, in a hypothetical mature oil reservoir through EOR operation. Simulations based on mass, energy and entropy balances, as well as economic analysis, were assessed for the process of CO₂ sequestration combined with EOR. This model takes into account the energy requirements for the whole CO₂ sequestration process, as well as the emissions inherent to the process. Additionally, a breakdown cost methodology is proposed to estimate the main financial determinants of the integrated EOR with CO₂ sequestration (costs of CO₂ purchase, compression, transportation and storage). Project evaluation is derived from a cash flow model, regarding reservoir production profile, price and costs, capital expenditures (CAPEX), operating expenditures (OPEX), carbon credits, depreciation time, fiscal assumptions etc. A sensitivity analysis study is carried out to identify the most critical variables. Project feasibility, as expected, is found to be very sensitive to oil price, oil production, and CAPEX. Moreover, there is the contribution from the mitigation of the greenhouse gas (GHG) by storing a significant amount of CO₂ in the reservoir where it can remain for thousands of years.