The evaluation methods for CO2 storage in coal beds, in China

Abstract

As a win–win technology, CO2 storage in coal beds could increase the CH4 recovery as well as CO2 storage in coal beds. The evaluation of CO2 storage capacity in coal beds is very important to guide CO2 storage technology. The present CO2 storage evaluation methods for coal beds only considered the adsorption trapping. But most coal beds have water. At least in China, 80% of coal beds have water. So the CO2 displacement trapping and dissolution trapping in reservoir water should be not ignored. In this study, aiming at the characteristics of China's coal beds, CO2 dissolution in water, CO2 displacement to formation water, CO2 adsorption in coal beds are considered and new CO2 storage evaluation methods for coal beds are proposed. And three calculation methods are introduced to determine the key parameters in these new evaluation methods. These methods can improve the reliability to calculate the CO2 storage capacity in coal beds. At last an example is discussed and the procession of evaluation is demonstrated. The evaluation results of the Qinshui basin prove the reliability of new evaluation methods, and indicate that the CO2 storage capacity in coal beds have a relatively large prospects.