Optimizing in-situ combustion gasification for enhanced clean hydrogen production with in-situ CO₂sequestration

This study aims to optimize in-situ hydrogen production from oil reservoirs using in-situ combustion gasification (ISCG), while simultaneously enhancing oil recovery and enabling CO2 sequestration. A validated 1D numerical model was developed using CMG-STARS, based on experimental data from a combustion tube setup. The effects of oxidizer compositions (ranging from 0.9O2/0.1CO2 to 0.21O2/0.79CO2) and steam injection rate (0.005-0.012 m3/day) on combustion behaviour, temperature profiles, gas production, and oil recovery were investigated. The optimal oxidizer composition of 0.9O2/0.1CO2 resulted in the highest oil recovery factor (ORF) of 95.28 % and sustained a peak temperature of approximately 600 °C. Increasing the steam injection rate from 0.005 to 0.012 m3/day led to an increase in total H2 production from 0.001 m3 to 0.544 m3. Additionally, the H2 mole fraction rose from 0.107 % to 42 %, marking the steam rate of 0.009 m3/day as optimal. The highest CO production of 0.58 m3 was achieved at the 0.5O2/0.5CO2 ratio, supporting its role in partial oxidation. For the steam injection rates of 0.0075, 0.009, and 0.01 m3/day the ORFs were 95.25 %, 95.28 %, and 92.42 % respectively. These findings demonstrate that ISCG is a promising technique for clean hydrogen generation, enhanced oil recovery, and CO2 management in heavy oil reservoirs.