Enhanced natural gas production using CO₂ injection: Application to sustainable hydrogen production

Significant strides in the use of enhanced oil recovery methods for oil production have been established. Nevertheless, carbon dioxide enhanced gas recovery (CO₂-EGR) has received less attention, despite its potential to offer both natural gas production and CO₂ sequestration benefits. Moreover, the potential of the produced natural gas to be utilized for hydrogen production through steam methane reforming (SMR) has not been fully acknowledged. This critical review aims to comprehensively examine the technical aspects of CO₂-EGR for hydrogen production. Specifically, the reviews explore the influencing factors (reservoir, injection fluid, and operational parameters), case studies (feasibility and, field operations), and challenges of CO₂-EGR to enable a sustainable hydrogen production via SMR. The study's key findings on operational parameters indicate that high pressure and moderate injection rates can improve EGR. In comparison to homogeneous reservoirs, heterogeneous reservoirs typically yield lower recovery rates. The molecular diffusivity of the injected gas on formation gas is influenced by several factors, including flow rate, pressure, temperature, connate water, brine saturation, and shale content, which can significantly affect recovery outcomes. Additionally, the temperature of the reservoir and whether the subsurface reaction after injection is exothermic or endothermic are important factors. The type of fluid phase used for injection, such as gaseous or condensate, also has a significant impact on recovery scenarios. Simulation studies have shown that injecting pure CO₂ or nitrogen, flue gas, or gas-altering gas with proper timing of reservoir operation can improve recovery. This review's finding is essential for identifying storage conditions that would lead to maximizing CO₂ – EGR for sustainable hydrogen production.