Coupled Enhanced Natural Gas Recovery and Blue Hydrogen (EGRBH) Generation

Abstract

Abstract Natural gas can be used to generate either blue or grey hydrogen depending on whether or not the carbon dioxide byproduct is captured and stored. When captured, the carbon dioxide (CO2) produced from a steam methane reforming (SMR) or partial oxidation (POX) process can be injected into the same natural gas reservoir for enhanced gas recovery (EGR) while simultaneously storing CO2. The objective of this work is the effective integration of these three major processes – blue hydrogen generation, carbon dioxide capture and storage, and enhanced natural gas production. Surface processes include separation of methane from CO2 and other inorganic and organic components in the produced natural gas. Produced CO2 will be injected back into the reservoir, and other components would be managed in ways standard to produced natural gas processing. An SMR or POX process followed by a shift reaction one will generate hydrogen and CO2 followed by separation of the hydrogen and CO2. To avoid a need for post combustion capture, continuous operation can use produced hydrogen to energize the SMR process. Integration of natural gas reservoir production, blue hydrogen generation, and CO2 injection back into the same reservoir leads to a process termed enhanced gas recovery and blue hydrogen (EGRBH). To optimize the reservoir management, analytical and numerical simulation models that address physical mechanisms such as CO2 diffusion, advection, and CO2 solubility in connate water provide guidelines on placement of injection and production wells, on their geometry (vertical or horizontal) and completion interval locations, and on well operating conditions. Displacing methane with CO2 is a miscible process with favorable mobility ratio, and simulations show that the methane recovery factor at CO2 breakthrough depends on both molecular diffusion and dispersivity related to reservoir heterogeneity. Continued production at constant methane rate enables additional blue hydrogen generation while increasing CO2 flow through the reservoir under declining average reservoir pressure. Injection of additional CO2 captured from other stationary point sources can achieve enhanced CO2 storage (ECS) up to a limit pressure less than the original reservoir pressure. The EGRBH process produces blue hydrogen at a price competitive with gasoline or diesel for transportation applications. When used for power generation, blue hydrogen decarbonizes natural gas fired generation at lower cost than can be achieved with post combustion capture from standard natural gas power plants. Blue hydrogen is also less than half the cost of so-called green hydrogen produced via electrolysis using electricity generated with renewable energy. This appears to be an ideal approach for developing and producing new natural gas discoveries.