CO2 storage by sorption on organic matter and clay in gas shale

In the work described in this paper, we developed simulations of methane production and supercritical carbon dioxide injection that consider competitive sorption of methane (CH₄) and carbon dioxide (CO₂) on both organic matter and the clay mineral montmorillonite. We used the results of these simulations to assess the potential for storage of CO₂ in a hydraulically fractured shale gas reservoir and for enhanced recovery of CH₄. Assuming equal volume fractions of organic matter and montmorillonite, amounts of CO₂ adsorbed on both materials were comparable, while methane desorption from clays was greater than desorption from organic material. CO₂ injection simultaneous to CH₄ production in two separate wells enhanced the contribution of methane desorption from 3535 to 6401 metric tons, while storing 82 metric kilotons of CO₂.