Hydrogen storage is a step forward to achieving low-carbon energy goals due to its potential to help with the intermittency problems of the renewable energy sources. Ample capacity of geologic reservoirs, such as aquifers, depleted reservoirs, and salt caverns, provide an attractive option for large-scale hydrogen storage. In the U.S., operational or depleted shale-gas reservoirs offer significant potential for hydrogen storage. However, retention of hydrogen in the tight, shale matrix and reactive formation damage may reduce well deliverability and cause significant hydrogen loss.
The objective of this study is to contribute to the technical assessment of the hydrogen-storage potential of shale-gas reservoirs by providing information on the injectivity and deliverability changes during storage operations. A compositional, numerical model of a dual-permeability, shale-gas reservoir with a hydraulically fractured horizontal well is used in the study.
The hydrodynamic behavior and biochemical interactions of hydrogen with the resident fluids and bacteria are simulated and their impact on the injectivity and productivity of the well is demonstrated. The effects of low relative permeabilities and low water and gas mobilities over a wide range of saturations are discussed. The impact of diffusion on hydrogen injectivity and deliverability is also demonstrated.
Results show an increase in methane concentration and a decrease in hydrogen concentration due to microbial activity, including methanation by the Sabatier reaction. Calcite dissolution has been considered as a source of CO2 for the Sabatier reaction; however, for the conditions considered in this work, limited hydrogen dissolution was found to be a more important constraint than the amount of available CO2 in the system.
The replacement of fossil fuels with renewable energy sources is proposed as the best option to alleviate the negative impacts of climate change. However, most of the renewable energy sources rely on uncontrollable atmospheric factors, such as the availability of wind or solar radiation (Engeland et al., 2017). This may cause seasonal energy surplus or shortages, as well as unpredictable interruptions in energy supply. Therefore, an essential requirement of any energy transition proposition is an energy storage technology to ensure uninterrupted supply of energy when the energy generation capacity falls short of the demand. Converting the surplus of energy into hydrogen, as an energy carrier, and storing for future use (Tarkowski 2019; Luboń and Tarkowski 2020) offers a promising solution to ease the energy intermittency concerns and provide sustainable energy supply from renewable sources.
