In Situ Hydrogen Generation Within Gas Reservoirs

Abstract

Nowadays, hydrogen is often considered as one of the prospective clean energy carriers. At the same time, the traditional hydrogen production methods also produce significant amounts of greenhouse gases or too expensive to be industrial scaled. In situ hydrogen generation in hydrocarbon-containing reservoirs can be one of the promising ways for low-carbon hydrogen production. However, the conversion of hydrocarbons into hydrogen under the hydrocarbon reservoirs conditions has practically not been studied. This work reports experimental results on the catalytic in situ hydrogen generation from methane under the conditions that can be achieved due to the thermal influence on gas-bearing layers. Hydrogen can be generated within gas reservoirs with non-zero residual oil saturation or in the fields with underlying oil-saturated layers due to the catalytic treatment of the reservoir followed by steam injection and/or in situ combustion. First, the thermodynamic restrictions for the process were determined. Then verification concept experiments were performed in the autoclave setup in static and dynamic modes with various operational parameters. The effects of temperature, pressure, and core model type on the hydrogen generation were investigated. Results show that temperature higher than 550 ºC should be achieved in the active zone of the target reservoir to convert significant amount of methane to hydrogen. The lower temperatures reached at the active zone are inefficient for the hydrogen generation. This effect can be explained by the thermodynamic restrictions and negative influence of the original core on catalyst activity. Nevertheless, hydrogen concentrations up to 70.8% mol. and 34.0% mol. were achieved in the experiments at 800 ºC in the presence of the inert (crushed alumina) and the original core models, respectively. At this temperature, strong reducing conditions influence the catalyst activity. Conducted experiments proved the main principles of the in situ hydrogen generation technology and evidenced that hydrogen generation in gas reservoirs is prospective when realized jointly with the catalyst treatment and in situ combustion method. This innovative technology can help humanity decarbonize the energy sector using unclaimed hydrocarbon resources of depleted and abandoned gas reservoirs without greenhouse gas emissions.