CO2 EOR Challenges and Opportunities to Enable CCUS Strategies

Abstract This paper provides insights on the current challenges and opportunities associated with the development CO2 EOR projects as part of CCUS strategies. These projects are strategic for the oil and gas industry, not only mitigate the impact of GHG emissions from current operations, but also to enhance their oil recovery. The paper shares how lessons learned from ongoing CO2 EOR pilot projects in ADNOC Onshore have allowed the optimization of surface facilities, material selection for well completions and helped identify limitations to find solutions and proposals to deploy new technologies and enable CCUS strategies. Since 2016, ADNOC Onshore has pioneered CO2 injection, both continuous and in WAG mode, using captured CO2 from Emirates Steel Industries under the Al Reyadah CO2 supply project (Sheikh, F, 2021; Hassan, S. et al 2021; Alklih et al 2019). Experience from the ongoing pilots was reviewed for potential cost optimization of the well design, while ensuring the same level of reliability and integrity of the completions from on-going Waterflood and HC WAG developments implemented in the same fields. CO2 composition and fluid conditions were reviewed along with reservoir monitoring and log acquisition to study recommend strategies for WAG cycle changes that would mitigate potential corrosion issues. Completions for CO2 WAG Injectors in ADNOC Onshore pilots have been traditionally applied in CRA material and employing wellhead heaters. These, represent high-cost elements in the drillex and CAPEX of WAG-CO2 development projects. Results show that for WAG-CO2 projects L-80 1Cr materials may be used in WAG Injectors significantly lowering the Drillex costs. Mitigation strategies include the use of viscous fluid spacers that will limit the contact between CO2 and Water during cycle changes. Well head and down-hole temperature surveys showed that CO2 cooling effect under ADNOC Onshore field conditions was not a concern and long term injectivity has not been significantly affected. As a result, CO2 Heaters have been removed optimizing the CAPEX of on-going CO2 project studies