The Impact of Thermodynamic Conditions on CO₂ Adsorption in Unconventional Shale Reservoirs Using the Volumetric Adsorption Method

Carbon dioxide (CO₂) injection is an enhanced oil recovery method that can increase oil recovery from different types of oil reservoirs. It has been recently applied in unconventional shale reservoirs for both enhanced oil recovery and CO₂ storage applications. This research explains the main mechanism of adsorption, which is the main force by which CO₂ can be stored in shale reservoirs, and then performs an experimental study to investigate the factors impacting CO₂ adsorption using the volumetric adsorption method. The review will cover the main definition of adsorption and how it can help in CO₂ storage. It will also include the mathematical equations used to obtain adsorption for the volumetric adsorption method. The experimental study then investigates the impact of three major parameters including CO₂ injection pressure, temperature, and shale volume on the adsorption capacity of the shale. The experimental results showed that the factors studies had a strong influence on the CO₂ storage potential. Increasing the CO₂ injection pressure increased the adsorption capacity, whereas increasing the temperature reduced the adsorption greatly. The shale volume strongly impacted the accuracy of the results obtained using the volumetric method and thus is an extremely important parameter in the design of adsorption experiments if the volumetric method is to be used. The parameters studied in this research should be accounted for when designing a CO₂ enhanced oil recovery operation if CO₂ storage is a part of the project.