Microbial hydrogen production from depleted hydrocarbon reservoirs: Evidence from field investigations and lab experiments

The study explores microbial Hydrogen (H₂) production in depleted hydrocarbon fields through field investigation and controlled experimental analyses (microbial process) using in-situ microbes, which thrive in thermophilic anerobic conditions of the hydrocarbon reservoirs. Gas and brine samples from various wells revealed H₂ presence in the range of 2–20 %, indicating microbial H₂ production potential in depleted hydrocarbon fields. Brine samples were characterized for their geochemical properties. Metabarcoding identified Clostridium as the most efficient H₂ producer, with other microbes including Hydrogenophaga, Desulfovibrio, Geobacter, and Thermomicrobium. In laboratory experiments, microbial cultures produced considerable hydrogen when grown in an anaerobic basal medium (ABM) enriched with 10 % v/v brine and 1 % v/v oil. The addition of oil significantly improved both the growth of the microbes and their hydrogen yield, providing valuable insights into the mechanisms of microbial hydrogen generation in hydrocarbon reservoirs.