Recent advances of in-well hydrogen production with integrated in-situ carbon dioxide sequestration: A comprehensive review

A thorough analysis of clean hydrogen production methods within oil and gas wells is provided. Focus is given on the recent advances in In-situ combustion (ISC), and In-situ gasification (ISG). Several factors influence in-well hydrogen production, including geological considerations such as reservoir characteristics and operating conditions, in addition to geochemical conditions involving reactants and reaction control. These factors collectively determine the feasibility and efficiency of in-well hydrogen production techniques. Case studies and field demonstrations which provide valuable insights into the practical application of these techniques are provided. Studies have shown that ISC can produce up to 16 % hydrogen, but ISG is an efficient method that can produce syngas with concentrations of up to 50 % hydrogen. Techno-economic evaluations estimated hydrogen production costs ranging from $0.23 to $0.68 per kilogram, depending on system design and operational conditions, with air separation units contributing up to 72 % of capital costs. Optimization studies revealed that an oxygen-to-carbon (O/C) ratio of 0.5 and a steam-to-carbon (S/C) ratio of 2 yielded peak hydrogen production at a reservoir temperature of 675 K. Technical challenges which include efficiency and productivity, effective monitoring, control, and overcoming technical limitations are discussed. The environmental challenges involving managing potential reservoir impacts, greenhouse gas emissions, water usage, chemical interactions, and subsurface integrity are clarified. The economic challenges addressed encompass cost analysis, market potential, and the integration of renewable energy sources. A novel framework for optimizing in-well hydrogen production processes by addressing critical techno-economic and environmental challenges is hence provided.