Assessing the Potential of Hydrogen Production from Hydrocarbon Reservoirs

Hydrogen generation within heavy oil reservoirs using in situ combustion gasification (ISCG) presents a cost-efficient approach for producing hydrogen at scale. Considering demands for more sustainable energy alternatives, integrating ISCG with downhole hydrogen separation techniques can provide a clean hydrogen source while concurrently storing CO2 within the reservoir. Despite extensive studies, including laboratory investigations, field implementation of this process remains at an early stage; nonetheless, it is emerging as an area of research interest. This study employs thermo-compositional and reactive transport simulations as tool in bridging laboratory-scale studies with field-scale applications, offering valuable insights into the complex mechanisms of ISCG and enabling assessment of potential hydrogen yields. Our simulation outcomes identify several critical factors influencing hydrogen production, including temperature, coke gasification, injected fluid composition, reservoir fluid residence time, and hydrogen consumption through methanation. Under controlled laboratory conditions, hydrogen can account for up to 35% of the gaseous product mole fraction along the length of the combustion propagation, though this proportion diminishes in more realistic subsurface conditions. The combustion process generates significant amounts of coke, which may subsequently react with the generated hydrogen to form methane during in situ transport. Our results indicate that methanation reactions can consume as much as 50% of the generated hydrogen, representing a critical limitation to net hydrogen recovery. Sensitivity analyses further indicate that both the injection rate and injected fluid composition strongly influence cumulative hydrogen yield and overall energy efficiency. This study highlights the importance of mitigating methanation effects and deploying efficient development strategies to optimise hydrogen recovery using ISCG methods in realistic reservoir conditions. These findings provide valuable insights for future field-scale applications and technological optimisation in hydrogen recovery from heavy oil reservoirs.