ISRM 2023 - PUBLICATIONS

T16: Underground storage for liquid and gaseous mediaDuo WANG (1,2), Xiao LI (1), Hang YUAN (3), Guanfang LI (1)1: Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China; 2: SINOPEC Petroleum Exploration and Production Research Institute, Beijing, China; 3: School of Geophysics and Information Technology, China University of Geosciences, Beijing, ChinaShale gas accumulation mechanism in the shallow burial depth: Insights from mechanical properties and methane adsorption capacityThe shallow burial depth shale gas reservoirs have great significance for low-cost development. Petrophysical characteristics and methane adsorption capacity are fundamental factors that control shale gas enrichment. We investigated petrophysical characteristics and methane adsorption capacity based on lithology and burial depth. Several samples from reservoirs and sealing formation were analyzed to elucidate the enrichment mechanism, applying N2 and CH4 adsorption, petrophysical test, and micro CT scanning. The results indicate that the combination of high clay content calcareous siltstone and shale has obvious sealing capacity comparing to siliceous shale, and less fractures could be induced because of uplift. Besides, a shallow shale gas enrichment model was proposed, methane adsorption capacity is highly related to the burial depth, in the ultra-shallow depth (<700 m), a rapidly decreasing trend can be observed under a normal pressure condition, while there is no obvious decline of the adsorption capacity in the overpressure reservoirs. | shallow shale gas; enrichment mechanism; petrophysical characteristics; methane adsorption
T16: Underground storage for liquid and gaseous mediaSophie MESSERKLINGER (1), Mikkel SMAADAHL (2), Daniel PÖTSCH (3), Carlo RABAIOTTI (2), Erich SAURER (4)1: University of Applied Sciences Upper Austria, Austria; 2: Eastern Switzerland University of Applied Sciences, Switzerland; 3: Salzburg AG, Salzburg, Austria; 4: Skava Consulting ZT GmbH, Salzburg, AustriaLarge rock caverns for heat storage in district heating networks – A comparative study for the city of SalzburgLarge heat storages play a key role for the implementation of renewable energy and industrial waste heat in heat distribution networks. One option is to use underground space for large heat storages. In this paper a case study for large underground heat storages in the heat distribution network of Salzburg is presented. Possible locations for large underground heat storages along the existing heat distribution network were identified, also based on the geological conditions. Two locations were selected and the temperature distribution in the underground around the heat storage cavern was numerically simulated using COMSOL with the aim to determine the energy losses and the temperature change at the ground surface. The results showed that the energy losses can be reduced considerably by >70% compared to insulated steel tank storages and that the surface temperatures are not much influenced by the heat storage below. | heat storage, rock cavern, shaft, numerical simulation, energy losses
T16: Underground storage for liquid and gaseous mediaHippolyte DJIZANNE (1), Benoit BROUARD (2), Grégoire HÉVIN (3)1: INERIS, France; 2: Brouard Consulting; 3: StorengyMechanical stability of a salt cavern used for hydrogen storageUnderground salt cavern storage is recognised as one of the most suitable technologies to meet the challenges of the new European energy system. With the advantage of being mostly impermeable to gases, salt caverns are currently the only structures used to store hydrogen on a massive scale underground. This paper studies the consequences of a rapid withdrawal of hydrogen on the mechanical stability of a salt cavern. Gaseous hydrogen cooling could generate rock salt dilation, cavern closure and tensile stresses at the cavern wall. Numerical computations using the finite element method help to evaluate the geomechanical consequences of a rapid depressurisation in a selected cavern for an underground hydrogen storage demonstrator in France. | salt cavern, hydrogen, worst-case scenario, salt dilation, effective stress
T16: Underground storage for liquid and gaseous mediaPhilippe VASKOU (1), Nicolas GATELIER (2)1: University of Cergy-Paris, France; 2: Geostock, Rueil-Malmaison, FranceWhat can be the future of underground storages in the context of green energy? - Geomechanical aspectsCompressed hydrogen is classically stored in steel overground tanks. Large underground storages of compressed hydrogen are extremely few whereas the challenge today is storing liquified hydrogen at very low temperature (cryogenic). Salt caverns are used for storing compressed hydrogen in gaseous state since the 1970s but suitable salt environments are limited and heterogeneously distributed, worldwide. Thus, storing compressed hydrogen in lined rock caverns (LRC) similar to compressed natural gas (CNG) is now envisaged. Currently there is only one example of LRC for storing CNG in operation and no compressed hydrogen rock cavern has been designed yet at an industrial scale. Regarding geomechanics, the conversion of salt caverns is relatively easy but more difficult for rock caverns, due to the required steel membrane and the quality of the host rock mass. The main design criteria and preliminary geomechanical modelling required for cavern creations and challenges for the conversion are also discussed. | hydrogen, storage, cavern, salt, conversion
T16: Underground storage for liquid and gaseous mediaSasan MORAVEJ (1), Mehdi SERATI (1), Mojtaba BAHAADDINI (2), David WILLIAMS (1)1: The University of Queensland, Australia; 2: Shahid Bahonar University of Kerman, IranThermomechanical Behaviour of Rock SaltThe stability and integrity of salt caverns are critical for ensuring their safety and long-term viability, especially when used for storing hydrogen on large scales. This study is aimed at understanding the failure mechanisms of rock salt under coupled thermo-mechanical stress regimes based on the study of rock salt dilatancy-compression boundary stress levels. Several tests were conducted using a high-temperature true triaxial testing facility on 50 mm high-purity rock salt cubes. Different temperatures of 30 °C and 100 °C were considered, along with a variety of stress values of 0, 5, 10, and 20 MPa for confining pressures. The results showed that the applied deviatoric stress and temperature both have significant coupling impacts on the peak strength and dilatancy boundary of rock salt. | Salt cavern, Dilatancy boundary, peak strength, intermediate principal stress, high temperature
T16: Underground storage for liquid and gaseous mediaLukas BAUMGÄRTEL, Feline KÖRNERLeibniz University Hannover, Hannover, GermanyThe fracture behavior of rock salt under present gas pressure in mechanical extension experimentsThe storage of large quantities of energy sources (e. g. natural gas or hydrogen) in rock salt caverns has regained particular importance in today's world. Therefore, the geomechanical design of caverns in rock salt formations is necessary to ensure a safe but also economic operation. Special attention has to be paid to the gas withdrawal phases and the processes resulting for the surrounding rock mass. When the stresses inside the rock fall below the internal gas pressure, effective tensile stresses can cause the development of infiltration fractures. A special triaxial cell was developed for the laboratory study of such stress states in rock salt. Cylindrical hollow rock salt test specimens are loaded mechanically with an axial, circumferential and internal gas pressure. The axial stress reduction leads to a rupture at different stress differences between axial and gas pressure which shows dependencies on the initial pressure state and temperature. | energy storage, rock salt cavern, infiltration fractures, laboratory testing
T16: Underground storage for liquid and gaseous mediaKarl-Heinz LUX, Tianjie PAN, Ralf WOLTERS, Jörg FEIERABENDClausthal University of Technology, GermanyConversion of existing natural gas storage caverns for hydrogen storage – some selected aspects to be consideredThe conversion of existing natural gas storage caverns for hydrogen storage requires the assessment of the mechanical integrity of the wellbore. The additional impact on the wellbore induced by cavern convergence due to long-term operation must be particularly considered. Numerical simulations of an existing cavern and its wellbore using the FTK-simulator are performed to investigate the stress and strain changes in the casing shoe, including casing, annulus cement, and contact interfaces during the operation. In addition, hydrogen transport in the casing shoe area at the borehole contour is numerically simulated during the mechanical integrity test. It is shown that the FTK-simulator can be successfully used to predict the TH2M-couped load-bearing behavior of salt cavern and wellbore throughout its entire life and provides a detailed insight into the development of stress and strain regarding the casing, annulus cement, and contact interfaces. | underground hydrogen storage, salt caverns, well integrity, mechanical integrity test
T16: Underground storage for liquid and gaseous mediaManouchehr SANEI, Mohammad FATEHI MARJIDepartment of Mining and Metallurgical Engineering, Yazd University, Yazd, IranInvestigating and evaluating the geomechanics of geological storage of hydrogen from methane decompositionWithout the use of fossil fuels, a large contribution to global development would certainly suffer. However, recent scientific developments and perspectives have made it possible to provide the required energy without carbon production, using renewable sources. While renewable energy sources may be a solution to reduce anthropogenic greenhouse gas emissions from fossil fuels, there are still many problems in this development path. Therefore, it is necessary to devise long-term storage to balance the intermittent supply and demand for this new technology. Hydrogen (H2) can be proposed as a suitable energy to achieve goals and meet the growing global energy demand. However, the successful implementation of a large-scale hydrogen-based economy requires large-scale storage. Therefore, in this research, the geomechanics of storage for H2 from methane decomposition and the works of the past in this field will be analyzed and reviewed, and scientific cases will be reported to do this. | Hydrogen, Underground hydrogen storage, Geomechanics, Numerical modeling, Experimental studies
T16: Underground storage for liquid and gaseous mediaZongze LI (1,2), Jinyang FAN (1), Marion FOURMEAU (2), Chao DU (1), Deyi JIANG (1), Daniel NELIAS (2)1: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, China; 2: Univ Lyon, INSA Lyon, CNRS, LaMCoS, UMR5259, Villeurbanne, FranceExperimental study on creep behavior of rock salt under complex stress pathsTo study the effect of stress path on the creep behaviors of rock salt, multi-stage loading and unloading of confining pressure creep tests under constant axial pressure have been carried out on rock salt samples. The results as follows: (1) Confining pressure is the dominant factor of deformation and can effectively restrain the propagation of microcracks in rock salt. (2) Strain hardening behavior of rock salt samples is observed during the loading process. Internal stress with the property of self-weakening grows and changes constantly with loading time, and the time required for weakening is relevant to the stress state and loading history. (3) Creep of rock salt is caused by effective stress, which is the difference between differential stress and internal stress. Whether the initial creep stage occurs and the delay time to the entry of a steady-state creep stage is related to the loading path. | rock salt; creep tests; stress path; loading and unloading; deformation mechanism
T16: Underground storage for liquid and gaseous mediaJames Edward John BURTONSHAW, Adriana PALUSZNY, Robert ZIMMERMANImperial College London, United KingdomNumerical Modelling of Induced Seismicity along a Fault during CO2 Injection into a Subsurface ReservoirInjection, storage, and production of fluids in geological media could be a pivotal technology in the energy transition. Injection of fluid into subsurface systems is known to have the potential to induce seismic activity. The present work models induced seismicity during CO2 injection using a three-dimensional finite element-based numerical simulator, the Imperial College Geomechanics Toolkit. Simulations quantify fault slip along a single fault in a five-layer domain of varying permeability. Fluid injection occurs at the left boundary over a period of hundreds to thousands of days, and induced seismicity is monitored during the injection period. Results for varying mesh refinement and properties are compared against a published scenario. The originally two-dimensional model is replicated in 3D, and the same set of material properties are considered, with permeabilities ranging from 10-14 to 10-19 m2. The simulations predict peak slip to within a few centimeters of that of the numerical comparison study. | Underground Fluid Storage, CCS, Induced Seismicity, Fault Slip, Meshing
T16: Underground storage for liquid and gaseous mediaStefan ZELZER, Thomas GEISLER, Thomas MARCHERInstitute of Rock Mechanics and Tunnelling, Graz University of Technology, AustriaA guidance for the optimal site location of Cavern Thermal Energy Storage (CTES)The production of energy using CO2-neutral methods faces an additional challenge to conserve surplus energy over longer periods of time and to be able to use it when required. One possibility for meeting this challenge is the use of CTES (Cavern Thermal Energy Storage). These CTES store surplus heat in the form of hot water and preserve it for a desired period. Many cities feature the necessary rock formations to build and operate these CTES. For this reason, a guideline has been elaborated that combines the most important geotechnical parameters with the local rock mass conditions. In addition, this guideline pays special attention to the geometric dimensions since these have a significant influence on the stratification of water within the storage medium. It is possible to make a first selection of possible sites and to investigate them in more detail with this geotechnical guidance. | Thermal Energy Storage, Underground Heat Storage, Site Selection Criteria, Thermal Stratification, Suitable Rock Mass
T16: Underground storage for liquid and gaseous mediaDaniel Hubert BÜCKEN (1,2), Tobias BACKERS (1)1: Ruhr-University Bochum, Germany; 2: geomecon GmbH, Berlin, GermanyHybrid CO2 based thermo-mechanical underground energy storage - a numerical geomechanical reviewThe energy transition requires new ways of effectively and safely generating and storing energy. Multi-fluid geothermal energy systems, such as flexible CO2 plume geothermal systems and porous medium compressed air energy storage can provide dependable baseload, dispatchable power to complement intermittent renewable energy sources, and underground energy storage capacities. Here, a supercharged hybrid gas-based energy storage (SH-GES) approach using CO2 to store pressure and temperature is analyzed from a geomechanical perspective. This is crucial for safe storage operations. Using fully coupled multiphase THM simulations, a generic fault-bound reservoir model is used to evaluate the effect of cyclic storage operations and variable injection temperatures on stress alterations in and around the reservoirs, shifts in seal integrity, and fault stability. The preliminary findings suggest that employing SH-GES for energy storage is a viable option. However, additional research is needed to gather more data regarding the geomechanical impacts and storage efficiency. | energy storage, compressed gas, THM simulation, geomechanics