An Innovative Combination of Thermal Enhanced Oil Recovery Process with Organic Rankine Cycle to Improve Energy Efficiency

Abstract

Abstract Most thermal enhanced oil recovery (tEOR) processes worldwide are trying to be optimized due to the energy transition and greenhouse gas reduction plans. In that sense, reducing natural gas as a fuel for steam generation and improving the energy injected vs. energy produced represent key drivers for heavy oil exploitation. Colombian case is not different; the challenge plans to reduce 51% of CO2 emissions by 2030 will require technology incorporation and disruptive ideas. Ecopetrol is evaluating the concept of in situ steam generation assisted by the mist water-air injection and combining this tEOR process with organic Rankine cycle (ORC) equipment to take advantage of produced fluids to generate electricity. The process involves simultaneous air and water injection into the formation, in mist-like flow generated at wellhead, promoting a combustion front development, and using the injected and reservoir water for the in-situ steam generation. This represents an impacting reduction in the use of natural gas as a fuel for traditional steam generation processes. A numerical model was developed to evaluate the injection scheme and forecast oil production, fluid temperatures, and produced energy. The sector model allows the identification of optimum scenarios regarding appropriate water-air injection rates and enthalpy to obtain the best incremental oil recovery, energy efficiency, and low carbon intensity. The results indicated that with mist water-air injection, the recovery factor increased between 30 to 45%, and the peak of produced power was double (up to 4 MW) compared to the conventional steamflooding scenario. Since natural gas is not required, carbon intensity reduction is between 30 to 60%. Additionally, combining oil produced by the mist water-air injection and power generation using ORC, the total energy recovery factor is 50%. This paper presents an innovative concept for in-situ steam generation coupled with ORC technologies. This combination led to better use of the heat transferred into the formation and reduced natural gas and water consumption. Additionally, the use of produced hot fluid represents an integrated process of enhanced energy recovery (EER) as a strategy to partially overcome high carbon intensity estimations in traditional processes and avoid stranded assets. Carbon intensity can be further reduced by incorporating Carbon Capture Usage and Storage (CCUS) strategies met Colombian energy transition plans.