Onshore Abu Dhabi Carbonate Saline Aquifer CO2 Storage - An Integrated Technical Feasibility Study

Abstract

Carbon capture and storage (CCS) is recognized as an important technology in the decarbonisation of the energy system and saline aquifers are potential geological storage candidates. A major integrated feasibility study was conducted to screen and rank carbonate saline aquifer candidates for subsurface CO2 storage, onshore Abu Dhabi. The objectives were to obtain a range of potential CO2 storage capacities and annual injection rates and establish CO2 technical feasibility by integrating subsurface, well performance, cap rock integrity and economic analysis. A candidate screening matrix was developed taking into account onshore Abu Dhabi saline aquifer geological characteristics. Saline aquifers "A" and "B" within the syncline area were among the highest ranked candidates. A large-scale 3D static model was developed, utilising seismic and well data. Extensive CO2 storage simulation runs were performed, covering sensitivities and capturing major storage process/mechanisms applicable to carbonate formation. Combining geomechanics, geoscience, well performance, integrity and dynamic modelling, a CO2 storage site design was completed with slanted/horizontal injectors drilled radially from a centralised well pad. Ranges of CO2 storage capacity and maximum injection rates were obtained, depending on number of injectors and accounting for water offtake in nearby areas. Additionally, CO2 plume migration within several tens of thousands of years was simulated to aid CO2 containment assurance. Separate studies were performed to locate potential CO2 storage surface sites and used as part of the input for CO2 pipeline and surface facilities high level design. CAPEX, OPEX and abandonment cost estimates were generated as input for economic analysis. A multi-disciplinary risk assessment was performed, identifying potential risk factors throughout the life cycle of CO2 storage. De-risking and mitigation measures were considered and a detailed measurement, monitoring and verification (MMV) plan was developed. This paper presents the first integrated study on saline aquifer CO2 storage technical feasibility in this syncline area. A novel integrated workflow is employed, from initial candidate screening through dynamic modelling, surface facilities and risk assessment to recommendations for additional data acquisition. Key aspects which improved on published major international CO2 sequestration assessments are highlighted. The results and conclusions offer valuable insights for other Operators considering or planning CO2 sequestration in saline aquifer projects.