A Parametric Study on In-situ Hydrogen Production from Hydrocarbon Reservoirs - Effect of Reservoir and Well Properties

Energy transition is a key driver to combat climate change and achieve zero carbon future. Sustainable and costeffective hydrogen production will provide valuable addition to the renewable energy mix and help minimize greenhouse gas emissions. This study investigates the performance of in-situ hydrogen production (IHP) process, using a full-field compositional model as a precursor to experimental validation The reservoir model was simulated as one geological unit with a single point uniform porosity value of 0.13 and a five-point connection type between cell to minimize computational cost. Twenty-one hydrogen forming reactions were modelled based on the reservoir fluid composition selected for this study. The thermodynamic and kinetic parameters for the reactions were obtained from published experiments due to the absence of experimental data specific to the reservoir. A total of fifty-four simulation runs were conducted using CMG STARS software for 5478 days and cumulative hydrogen produced for each run was recorded. Results generated were then used to build a proxy model using Box-Behnken design of experiment method and Support Vector Machine with RBF kernel. To ascertain accuracy of the proxy models, analysis of variance (ANOVA) was conducted on the variables. The average absolute percentage error between the proxy model and numerical simulation was calculated to be 10.82%. Optimization of the proxy model was performed using genetic algorithm to maximize cumulative hydrogen produced. Based on this optimized model, the influence of porosity, permeability, well location, injection rate, and injection pressure were studied. Key results from this study reveals that lower permeability and porosity reservoirs supports more hydrogen yield, injection pressure had a negligible effect on hydrogen yield, and increase in oxygen injection rate corelated strongly with hydrogen production until a threshold value beyond which hydrogen yield decreased. The framework developed in the study could be used as tool to assess candidate reservoirs for in-situ hydrogen production.