Biogenic hydrogen production from oil hydrocarbons at geological carbon storage conditions

We found that supercritical CO₂ and the availability of protein-rich matter in depleted oil reservoirs can result in the biogenic production of H₂ from oil hydrocarbons by indigenous microbial communities. Our experimental results support the hypothesis that a decrease in pH to acidic levels due to the dissolution of supercritical CO₂ into the formation water and availability of protein-rich matter favors the activity of H₂-producing microbial communities over the activity of H₂-using microbial communities. To determine where, when, and how much H₂ could be produced in a depleted oil reservoir injected with CO₂ and produced water (PW) supplied with protein-rich matter, we simulated the biogenic production of H₂ for the Morrow B sandstone reservoir. Simulations were conducted using CO2Bio, a program developed to simulate the multiphase bio-geochemical reactive transport of CO₂-CH₄-H₂-H₂S gases in geological carbon storage (GCS) sites. The microbiological capabilities of CO2Bio are validated against batch reaction experimental results. Our field-scale simulation results indicate that 154 – 1673 kg of H₂ could be produced after 100 days of CO₂ and PW co-injection into a single well of radial flow, and that sandstone reservoirs are more suitable than carbonate reservoirs to produce H₂ from dissolved hydrocarbons. Based on the obtained experimental and simulation results, we propose a new H₂ production method that couples GCS and PW disposal in depleted oil reservoirs to attenuate environmental and energy issues related to global warming derived from atmospheric pollution with CO₂, risk of freshwater resources contamination with PW, and depletion of energy resources.