A viable business case has posed a challenge for CCUS (carbon capture, utilization and storage) projects and the aspirations of sustainability. With its vision to further expand its EOR portfolio and positively contribute to sustainability through CO2 injection, ADNOC Onshore started to contemplate new ways of implementing carbon capture in a more profitable and environmentally responsible manner. A CCUS Study was initiated to identify the optimum trade-off between key variables, such as injected CO2 purity, in order to minimize carbon footprint and cost without altering reservoir oil recovery. This paper presents an innovative study to understand optimal design of a CO2 recovery plant in collaboration with Sustainability and CO2 capture experts.
The team explored, in a synergized manner, the subsurface and surface aspects of CO2 capture and conducted reservoir simulations, techno-economic assessments of the surface facilities, reviews of the state-of-the-art CO2 technologies, as well as quantifying the carbon footprint reduction. The prevalent concept that higher CO2 purity results in a higher oil recovery needed to be validated. Therefore, several CO2 purity levels were investigated by extensive reservoir modelling and authenticated by lab experimental analysis.
The study focused on a specific future project and estimated that capturing the CO2 breakthrough would segregate millions of tons of CO2 per year, approximately equivalent to the emissions of 5 billion car miles per year. The corresponding estimated value could be drastically decreased, if the system's designed CO2 purity is decreased.
The main findings demonstrated that reducing the CO2 purity from 99% to 85% has inconsequential effect on the field recovery factor and negligible increase in Minimum Miscibility Pressure and required surface compression capacity. This can lead to a simplification of the carbon capture plant, with less equipment and footprint, and significant reduction in CAPEX (up to 40%), OPEX and GHG emissions.
This collaborative effort proved that a profitable business case is achievable from CCUS project, provided that the right parameters are assessed and optimized. The cost and energy footprint of the carbon capture facilities are driven by the concentration of CO2 in the feedstock and the purity of the CO2 required for injection purposes.
With an attractive economical model, future CCUS projects, such as the project under study, with its environmental contribution will become viable financial options. Looking for such options is critical particularly for projects targeting the replacement of current hydrocarbon injection with CO2 injection in the existing developments, while expanding CO2 injection into new development areas. This will significantly reduce the country’s global carbon footprint, as CO2 producing industries will be able to offset their carbon emissions footprint by sending their CO2 streams to ADNOC Onshore’ s facilities for injection and sequestration into subsurface reservoirs.
