Real-time Monitoring of Rock Geomechanical Properties During scCO2 Storage in Deep Saline Aquifers

Saudi Arabia targets net zero CO2 emissions by 2060, which requires a lot of logistics and accelerated research and technologies. One potential method to reach the target is c...carbon capture and storage (CCS) in a subterranean formation. There are a few mechanisms of CO2 storage, such as dissolution trapping, structural trapping, residual trapping, adsorption trapping, and mineral trapping. We recently received a funded project by Saudi Aramco to investigate CO2 storage in deep saline carbonate aquifers, taking advantage of its solubility in brine. The interaction of CO2 with water at high pressure and temperature forms carbonic acid with a pH ranging from 3 to 4. Hence, wormholes will be created due to the reactivity of carbonic acid with limestone. However, the literature lacks an understanding of the factors impacting wormhole generation pace, such as injection velocity, pressure, temperature, salinity, porosity, etc. Also, knowledge about wormhole impacts on the geomechanical stability of the wellbore and reservoir is lacking. At KFUPM, we can run coreflooding experiments to mimic CO2 storage. Nevertheless, we cannot measure the geomechanical properties and capture the wormhole image in-situ while injecting CO2. Therefore, this proposal is targeting utilizing the high-pressure, high-temperature (HPHT) core holder with triaxial stress and CT scan capabilities in Prof. Anthony Kovscek laboratory at Stanford University. It is of note that Prof. Anthony is a leading expert in the area of CO2 storage. The proposal objectives will be capturing high-resolution CT-scan images of wormhole generation during sc-CO2 injection at HPHT and high stresses. Also, the real-time axial and volumetric deformation will be measured in situ as the wormhole propagates. Finally, the setup can measure the change in the sample compressive strength (CS) due to the formed wormhole. We will be the first to utilize such a setup to capture the geomechanical effect of CO2 storage and wormholing in limestone specimens statured with brine. We are aiming to produce high-quality scientific papers from this research idea. It will also complement the ongoing study with Saudi Aramco on CO2 storage. But most importantly, we will seek to create similar expertise at KFUPM. Also, future collaboration through independent or funded research projects should be targeted after the end of the program.