Advances in Subsurface Energy Exploitation and Storage

The special collection on the Advances in Subsurface Energy Exploitation and Storage is available in the ASCE Library (https://ascelibrary.org/jleed9/subsurface-energy-exploitation-storage).

Due to the effects of global warming and emissions, the world is transitioning its environment and energy to one that is green and sustainable. Given the continuous increase of global energy demand and the many uncertainties of energy supply ahead, subsurface energy will continue to play a crucial role during this transitional process. To address the global warming challenges, one should pay special attention not only to the stability and availability of subsurface energy but also to developing transformational technologies for subsurface energy systems to contribute to oil and gas development, including geothermal energy extraction, carbon dioxide geo-sequestration, and underground hydrogen storage.

With the increase in crude oil demand and the continuous decline of conventional oil and gas production, the huge potential of unconventional oil and gas has attracted global attention. Tight oil is a typical unconventional hydrocarbon resource, and the special properties of tight reservoirs are low porosity, low permeability, and complex pore structure. In past studies, many works were conducted to analyze tight reservoirs sedimentology, but there has been little research on diagenesis and diagenetic facies. Zhang et al. (2022) analyzed the diagenesis of a typical tight sandstone reservoir by a combination of scanning electron microscopy (SEM), energy dispersive spectrometry, and X-ray diffraction. To monitor and quantify the imbibition behavior in the tight reservoir, Meng et al. (2022) adopted one-dimensional and two-dimensional nuclear magnetic resonance (NMR) to analyze the imbibition behavior. To characterize the gas-bearing capacity in shale rock, which is another typical unconventional hydrocarbon resource, Dong et al. (2023) characterized Langmuir’s volume and Langmuir’s pressure using well-logging data.

Geothermal energy is a renewable resource, and attracting more and more attention. Hot dry rock, one of the geothermal resources, especially is the primary direction of future geothermal development due to its wide distribution and huge reserves. However, fracturing has to be conducted to create an artificial flow region. Hydraulic fracturing is closely related to geologic structural discontinuities, but many of the hot dry rocks possess natural fractures, quartz veins, and lithological interfaces. The influence of these structural discontinuities on hydraulic fracturing propagation is unclear, and thus a comparative study combining lab experiments and numerical simulation was carried out (Xie et al. 2022).

Carbon dioxide geological storage and underground hydrogen storage have been the frontiers of the energy transition of the petroleum and coal industries. However, the similarities and differences between these two geo-storage methods are still confusing. Micro- and macro-experiments and simulations should be combined to analyze the seepage and leakage risk. Wang and Wu (2023) first compared their difference in hysteresis using a method of pore-scale network modeling, and then storage capacity and sealing security were analyzed by field-scale numerical models.

We hope the special collection will act as reference material for practitioners of related research, and that it will provide a solid contribution to the scientific discourse on subsurface energy exploitation and storage.

We thank all the contributors to this special issue for their scholarly submissions and the reviewers who spent their valuable time and efforts to provide timely reviews. We also thank editor in chief Dr. Chung-Li Tseng for his encouragement and guidance. We hope that the papers assembled in this special issue will open up further research on this topic.