The effect of H2S content on acid gas migration and storage in shale reservoir by numerical simulation

Acid gas injection is one of the most effective strategies to deal with waste gas generated during the development of sour oil and gas reservoirs. This study numerically investigates the effect of H₂S content on the acid gas migration and storage in shale reservoirs. The results indicate that the variations of acid gas density, viscosity, solubility, relative permeability, and capillary pressure caused by different H₂S contents have great influence on the acid gas plume migration. When acid gas is in gas state, the maximum horizontal flow appears at the lower part of the reservoir after 5 years, and the horizontal migration distance first decreases and then remains unchanged with the increase of H₂S content. Hereafter, the maximum horizontal migration distance appears at the top of the reservoir, and the horizontal migration distance first increases and then remains unchanged with the increase of H₂S content. When acid gas is in liquid state, the maximum horizontal migration distance appears at the lower part of the reservoir in the early stage of injection. The horizontal migration distance decreases with the increase of H₂S content. Subsequently, the maximum horizontal migration distance first decreases and then increases. The vertical migration distance increases gradually with the increase of H₂S content until the acid gas reaches the top of the reservoir, and then the vertical migration distance remains unchanged. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.