Speaker
Description
Carbon sequestration and hydrogen storage at large scales require suitable subsurface formations, with shale playing critical roles in both scenarios. In conventional reservoirs, shale acts as a caprock, preventing the upward migration of injected gases. In unconventional reservoirs, hydraulically stimulated shale contributes to storage by providing fractures, cracks, and pore spaces.
The injection of gas from the surface induces shifts in chemical equilibria due to rock-water-gas interactions. While mineral dissolution and precipitation have been extensively studied for their effects on pore structure and hydraulic conductivity, redox reactions remain less explored. These reactions, however, are crucial due to their implications for nutrient cycling, microbial activity, and heavy metal mobilization.
This presentation will cover my recent studies that involve iron and sulfur redox reactions in shale after either carbon dioxide or hydrogen injection. These experiments were designed to simulate near-wellbore conditions where shale is exposed to relatively fresh injected gas in the presence of formation brine, with some systems also incorporating wellbore cement. Our findings indicate that in carbon sequestration systems, the injected gas shifted the environment toward oxidative, whereas in hydrogen storage systems, it became chemically reductive. The extent of these redox reactions was influenced by complex factors, including the injection sequence and the presence of wellbore cement.
| References | Anna Lisa Herring |
|---|---|
| Country | United States |
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