Integrated CO2 Storage and Geothermal Energy Extraction from Fractured Reservoirs: A Multi-Scale Laboratory Experiment and Numerical Modeling Approach

Reducing the fossil fuel consumption and associated carbon emission, along with developing clean sustainable energy, has become a common strategy globally. Gulf countries, including Oman, are strategically diversifying petroleum-dominant economy and projected a tremendous renewable energy growth in the next few decades. In addition to the solar and wind energy resources, considerable low-enthalpy (around 100 oC) geothermal energy sources are hidden underground in North Oman to be explored and utilized. In previous studies, integrated CO2 geological storage (CGS) and CO2-circulated plume geothermal production (CPG) using oil-depleted reservoirs in North Oman has been numerically demonstrated a techno-economically feasible approach to store CO2 underground and to generate clean geothermal energy. CPG is more efficient than conventional water-based approach, particularly for low-enthalpy geothermal reservoirs. Depleted oil/gas reservoirs are well characterized with proven storage capacity and sealing structures, and have most of the required infrastructure. Applying CGS-CPG in these reservoirs can save a big share of start-up cost and enable harvest of Oman's low-enthalpy geothermal resources cost-efficient, in addition to carbon reduction benefits. However, those studied reservoirs are synthetic by assuming homogeneous formations and using averaged parameter values for hydro-geothermal properties. Realistic oil/gas reservoirs in North Oman are fractured with fault-network. Ignoring spatial heterogeneity and these fracture features of the reservoir may cause huge local errors in evaluation of realistic condition. This project aims to bridge this gap and to realize CGS-CPG approach in more realistic field reservoirs from synthetic reservoirs by multi-scale laboratory experiments. This challenging project will be jointly accomplished by Sultan Qaboos University (SQU) and Chinese Academy of Sciences (CAS). Laboratory pore-scale and core-scale flooding experiments using reservoir rock samples are conducted in China and Oman, respectively. Reservoir-scale evaluations of the integrated CGS-CPG approach in fractured carbonate reservoirs based on the data from laboratory experiments are jointly carried out by SQU and CAS. Following this project, a joint "virtual laboratory" may be established between SQU and CAS to enhance collaboration in the field of geothermal energy, carbon sequestration, and CO2-enhanced oil/gas recovery in long term.