Study of Temperature Effects on Economic Performance of CO₂ Enhanced Shale Gas Recovery

CO₂ displacement has been proposed to enhance shale gas recovery and unlock a big potential market for CO₂ beneficial utilization. Theoretically, gas adsorption is inversely related to the temperature, so gas can be desorbed by elevating the temperature. This paper investigates the economic performance of enhancing shale gas recovery by injecting CO₂ at high temperatures through displacement as well as desorption by rising temperatures. Influences of operation temperature and injection pressure were studied for three potential shale plays in China. Study results show that both factors exerted obvious impacts, and CO₂ procurement was the largest cost component. It is found that the net revenue was not always proportional to the operation temperature, but more controlled by the injection–production ratio. This is because of the different temperature impacts to the various patterns of adsorbed CH₄ and CO₂ contents. Consequently, in some cases, more CO₂ is needed to displace CH₄ when operation temperature is raised, resulting a higher cost. The modeling results demonstrate that based on the adsorption characters of reservoirs, the productivity and profitability of CO₂ enhanced gas recovery can be further improved by choosing appropriate operation temperatures.