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Influence of salt and non-salt on the integrity of caverns in homogenous and inhomogeneous salt formations (after Axel, 2007).
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Salt rock has been used as hast rock to storing hydrocarbons and disposing nuclear wastes because of its low permeability. On other hand it deforms under even low deviatoric stress which threatens the structural stability of salt caverns. Rock mechanical stability is one of important stages in salt cavern’s design and construction, though mechanica...
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Context 1
... stress becomes Hydrostatic. At such the salt mass stress redistribution and resulting in the induced deformation around cavern tends to be uniform by which long term and stability of the cavern is satisfied. In contrast, in some areas (particu- larly in bedded salt formation) rock salt and non-salt rock's deformation would be non-uniform (Fig. 2). In addition, the integrity of caverns constructed in inhomogeneous salt struc- tures no longer solely relies on the quality of the surrounding salt: they also have to rely on the interaction between differ- ent geological formations (Axel, 2007). As tightness is a decisive factor for storing in salt caverns, researchers focus on the ...
Citations
... Salt caverns gradually shrink over time [67] mainly due to the continuous deformation (creep) of the salt [68]. This deformation occurs when shear stress is induced by the pressure differential between the internal cavern pressure and the in-situ stress of the surrounding rock salt [68]. ...
... Salt caverns gradually shrink over time [67] mainly due to the continuous deformation (creep) of the salt [68]. This deformation occurs when shear stress is induced by the pressure differential between the internal cavern pressure and the in-situ stress of the surrounding rock salt [68]. The volumetric shrinkage rate of the cavern should be controlled to remain within 6% after 5 years of operation, and under 20% for a 20-year operational period [69]. ...
The refining industry is a major hydrogen consumer, mainly relying on fossil fuel-derived hydrogen. While recent literature has focused on the production of hydrogen from water electrolysis, (waste) biomass gasification is another effective method for low-emission hydrogen production, and the refining industry is well positioned for its rapid adoption. This study conducts a techno-economic assessment of the whole supply chain of hydrogen for oil refining and analyses the LCA-climate change for residual biomass gasification and water electrolysis pathways. The potential economic and environmental benefits of combining both production methods are also analyzed. A real case study featuring four different scenarios, using data from a refinery, coupled with local data and future projections for potential curtailment and electricity prices, is included. The hourly hydrogen generation and demand profiles of the refinery were analyzed to accurately assess storage requirements. Results indicate that combining both technologies does not result in clear environmental or cost benefits, with residual biomass gasification emerging as the most advantageous configuration for the base case. Sensitivity analysis reveals that hydrogen produced via electrolysis may become more cost-effective if residual biomass prices are high enough. The importance of underground storage (salt cavern) is highlighted due to its low investment, while other storage methods can significantly increase the Levelized Cost of Hydrogen (LCOH). This study demonstrates that hydrogen production through gasification can be less carbon-intensive and more cost-competitive than electrolysis. Achieving low LCOH values and greenhouse gas emissions is feasible in all scenarios, indicating that both water electrolysis and residual biomass gasification are economically viable options for contributing to a low-emission global energy system.
... The inherent stability of these structures mitigates the likelihood of cavern collapse or structural failure, thereby minimizing the potential for CO 2 leakage (Rogers III, 2023).6) Salt caverns have excellent ductility, i.e., when subjected to the high pressures and temperatures found deep underground, slowly deforming and flowing over millions of Table 2 Advantages and disadvantages of rock salt as host rock (Habibi, 2019 Fig. 4. Three steps involved in solution mining: a) Initial phase, b) Intermediate phase, and c) Complete phase (Li et al., 2022). ...
Permanent CO 2 sequestration in the salt caverns seems to be one of the best geological storage options that can be used to reduce anthropogenic greenhouse gases emissions (GHGs) from the atmosphere. However, salt caverns are rarely used because other geological options are more available; hence, they are used for energy source storage for future use due to their high deliverability and ability to quickly switch an injection well to a production well. Nevertheless, salt caverns seem to have low leakage risk compared to other geological storage options due to low permeability, high ductility, and self-healing ability after deformation. In this review, recent advances in CO 2 sequestration in salt caverns have been presented. It has been revealed that salt caverns have great potential to store CO 2 permanently to help to mitigate global climatic change. Salt caverns built offshore in ultra-deep water in Brazil and Lotsberg salt formation, Alberta and Saskatchewan, Canada, have a great potential to store ~108 million tons of CO 2 and 3500 megatons, respectively. Furthermore, from geochemical Modelling and simulation, it has been revealed that these caverns can store a substantial amount of CO 2 , specifically 4 billion sm 3 or 7.2 million tons, under conditions of 45 MPa pressure and a temperature of 42 • C. The identified research gaps in this study will motivate researchers and stakeholders to conduct more research on developing technology to sequestrate CO 2 into salt caverns as a reliable geological option to mitigate global climate change in places where other storage options are not available.
... Many scholars have studied the deformation behavior of rock salt and the influence of the stress state on the stability of the resistance structures (room, pillar, and floor) carried out in the salt massifs. Rock salt formations (seams and lenses) were considered the geological environment favorable for the deep storage of radioactive waste, petroleum products, and industrial waste [3,[5][6][7][8]. For this reason, salt deposits have been the subject of numerous studies and research carried out in laboratories around the world. ...
... At the current stage, the theoretical treatment of the pressure regime includes a large number of problems; however, difficulties arise when solving the problems encountered in mining engineering practice through classical analytical methods. That is why many concerns are directed in particular towards finding research methods, respectively, appropriate calculations for the problems and precision required by the mining activity [11,12,17,18,20,24,29]; others refer to finding experimental procedures for determining the behavior of underground constructions of all kinds using different modeling systems and in situ measurements [7,8,19,20,24,25,[28][29][30][31][32][33]. Finding that, in the end, the analytical way is not at all inferior to the experimental one, the analytical and numerical methods of solving the most diverse problems encountered in practice have also seen an exceptional development [34][35][36]. ...
... In the case of the reopening of some mining fields within the salt panels and the exploitation in depth with square pillars, the establishment of the optimal parameters of the elements of the exploitation system requires the establishment of the loads that appear in the surrounding salt massif (the natural stress state); the qualitative-quantitative determination of the way of distribution of the secondary stress state in the pillars; evaluating the bearing capacity of the pillars; and establishing their geometric elements [27,[37][38][39]. The way of appearance, distribution, and manifestation of the secondary stress state, as well as its magnitude, is not only a characteristic of the salt massif because it is not dependent only on its quality but is a function of the "complete and inseparable interaction" of a complex of natural, technical, mining, and organizational factors [7,[11][12][13][14][15]22,23,31,36,39,40]. Studies related to the analytical assessment of the stability of the dry rock salt exploitation system with the increase in depth were carried out in the paper [12]. ...
The mining method that is still often used in salt deposits is the room-and-pillar mining method, in which the dimensioning of the most requested element in the system is followed. The pillars are the elements subjected to the greatest loads. Knowing the size and distribution mode of the secondary state of stress—deformation—is a necessity that can lead to the design and realization of stable, reliable underground excavations. This paper proposes an analytical assessment model of the secondary stress state in the pillars between the operating rooms, as well as in the whole system room–pillar–floor, based on the results obtained from laboratory research through modeling and in situ research. For this purpose, the evaluation of the secondary stress state was carried out considering the following methods: (1) the dimensioning method based on the theory of limit equilibrium, taking into account the effective stress in the pillars; and (2) the mechanics of the continuous environment based on the design of some analytical models for evaluating the secondary stress-deformation state in the pillar and floor. The exploitation of one of the largest salt deposits in Romania is used as a case study, and the stability of the exploitation system with rooms and pillars is evaluated by analytical methods. The secondary state of tension was calculated at different points on the height of the pillar. Through the proposed algorithm, the value of the axial component of the secondary stress state at different points along the axis of a pillar located at a depth of 100 m varies between 1.498 and 1.657 MPa, compared to the value obtained by the finite element method and in situ measurements, which was 1.64 MPa. The comparison revealed a high degree of agreement between the results obtained for the depth of 100 m using both the FEM and laboratory and in situ measurements. This suggests that the proposed algorithm is a reliable method for predicting the secondary stress state. The presented algorithm can be extended in the field of mining deposits, where mining methods with rooms and pillars are used.
... Some subsidence occurs under the reservoir level. Mechanical factors (such as the nonlinear behavior of rock salt), thermal factors (such as temperature changes during injection and production), and hydraulic factors (such as salt permeability and viscosity of the stored material) affect the short-and long-term behavior of salt caverns (Habibi, 2019). ...
Safe and effective large-scale storage of hydrogen (H2) is one of the biggest challenges of the global energy transition. The only way to realize this is storage in geological formations. The aim of this study is to address and discuss the reservoir engineering (RE) aspects of geological H2 storage (GHS). The study is based on two sources: first, a comprehensive literature review, and second, experimental and numerical work performed by our institute. The current state of the art regarding the principles of reservoir engineering on the application of GHS is reviewed and summarized.
Atypical properties of H2, with its lower density, viscosity and compressibility factor higher than one, increase uncertainties in the definition of capacity, injectivity, and confinement. In addition, the abiotic and biotic reactivity of H2 should be considered in the associated changes in petrophysical properties and molecular mass transfer in subsurface storage formations. Therefore, both geochemistry and reservoir microbiology are inseparable components of reservoir engineering of GHS. The sealing of H2 storage in a porous reservoir with caprock is due to the interplay between potentially higher capillary threshold pressure but higher diffusivity of H2, while the technically impermeable assumption of most deep salt formations can be considered as valid for H2 storage in caverns. Such changes can also affect the injectivity of H2 through plugging or dissolution. Well integrity is of particular concern when abandoned-old gas wells are reused. Especially at higher temperatures, hydrogen can behave more actively to support metal oxidation processes at the casing-cement contact and microbiological activity can promote these reactions. In addition, the permeability of the hardened cement samples to H2 is highly dependent on the effective pressure.
An overview of the reservoir engineering aspects of GHS is compiled from recent publications. We integrate key findings with our experimental results to provide essential guidance for front-end engineering and challenges to be addressed in future work. Monitoring of the reservoir pressure, as an indicator of microbial activity, is of great importance. Therefore, measures to control microbial activity have to be drawn, taking into account the site-specific characteristics.
... Creeps are generated over time and rapid cycles worsen creeps (Wallace et al., 2021). Habibi (2019), investigated the effects of mechanical stress and thermal effect on salt caverns and concluded fracture stress is very dependent on the rate of operation cycles. Thus, it is necessary to predict the evolution of stress to ensure safety of the storage facility over its cyclic life up to abandonment. ...
Hydrogen storage holds the potential to address the intermittency of renewables in the power sector as well as provide low-cost emissions-free energy. However, hydrogen (H2) as an energy carrier has a low density and low energy per unit volume at standard conditions. This significantly complicates large-scale storage using chemical and physical methods. Aquifers, salt caverns, and depleted/abandoned oil and gas fields are some of the subsurface options that can be used to store hydrogen underground because they possess the requisite volumes to store H2 at higher pressures. In this study, the recent interest in exploiting salt deposits in North Dakota as hydrogen storage sites is addressed. The Pine salt in the Spearfish Formation and the "A" salt in the Opeche Formation are the thickest and most prevalent of these salts, making them the most viable candidates for these types of ventures. We tested the feasibility of storing hydrogen by analyzing the behavior of the salts through geo-mechanical characterization. We estimated the mechanical properties of the rock salt from log data and considered the stresses of the salt formation to aid understanding and determine possible limitations. Geomechanical characterization showed a typical behavior of stresses, Sv>SH> Sh.
INTRODUCTION
The intermittency of renewable energy resources has created an urgent need for energy storage. Deployment of energy storage options will accelerate flexibility in grid operations and provide energy that can be applied to a diverse portfolio of industries. It can also provide environmental benefits by improving the overall efficiency of the power grid and providing a basis for the broader adoption of renewable energy thus reducing harmful emissions to the atmosphere (Uliasz-Misiak et al., 2022). According to Tarkowski & Uliasz-Misiak (2022), H2 is a reliable energy carrier that can play an important role in decarbonizing our current energy system. Hydrogen storage can be used to supplement energy demands associated with seasonal heating needs and peak load (Laban, 2020). The challenge with hydrogen however is that it has a higher energy per unit mass than any other liquid fuel. As an energy carrier, H2 has a low density of 0.089 kg/m3 at standard conditions. As such, it is difficult to store large volumes using chemical and physical storage methods (Lord, 2014). Currently, H2 storage can be stored on a small scale as compressed gas at around 5076 – 13778 psi in type 2, 3 or 4 tanks. In order to store gas at such high pressures, the capital and operational expenditures are significant. On medium scale, it can be potentially stored as a gas in spherical vessels at low pressures of ∼290psi thus requiring larger volume (Papadias & Ahluwalia, 2021).
... On the other hand, convergence greatly complicates the final abandonment of caverns when they are no longer suitable for further storage after a certain number of storage cycles. The increase in pressure inside a sealed cavern due to convergence may lead to fracturing of its roof, resulting in the loss of cavern tightness [19][20][21]. To a large extent, the risk of cavern roof fracturing depends on the rate of the pressure buildup [22,23]. ...
The paper aims to give a universal methodology for assessing the storage capacity of a bedded rock salt formation in terms of the operational and strategic storage facilities for liquid fuels. The method assumes the development of a geological model of the analyzed rock salt formation and the determination of the salt caverns' size and spacing and the impact of convergence on their capacity during operation. Based on this method, the paper presents calculations of the storage capacity using the example of the bedded rock salt formations in Poland and their results in the form of storage capacity maps. The maps show that the analyzed rock salt deposits' storage capacity in northern Poland amounts to 7.1 B m 3 and in the Fore-Sudetic Monocline to 10.5 B m 3 , in the case of strategic storage facilities. The spatial analysis of the storage capacity rasters, including determining the raster volumes and their unique values, allowed us to quantify the variability of the storage capacity in the analyzed rock salt deposits.
... This includes the effects from both mechanical and thermal loading from injection/withdrawal cycles and the effects these can take on the integrity of the surrounding formation. Habibi investigated the stability criteria required for both mechanical and thermal cyclic loading, stating that the fracture stress for the formation is a function of the rate of operation cycles [49]. This is exacerbated when fast cycles are considered, reducing the time increment in the changes in deviatoric stress (difference between internal pressure and geostatic stress) [49]. ...
... Habibi investigated the stability criteria required for both mechanical and thermal cyclic loading, stating that the fracture stress for the formation is a function of the rate of operation cycles [49]. This is exacerbated when fast cycles are considered, reducing the time increment in the changes in deviatoric stress (difference between internal pressure and geostatic stress) [49]. This suggests that although technically capable, the creep generated from ten cycles per year, may prevent such implementation. ...
... Furthermore, with increasing heterogeneity, additional deviatoric stresses between salt and other lithology need to be considered [50]. This is further complicated by mechanical properties varying on a case-by-case basis due to the environments in which the formation were formed, as well as sediment components, crystal geometries, content and distribution of impurities and tectonic histories [49]. Thermal stresses, induced through gas injection temperature, can result in microfracture development, a consequence of the tensile stress which it subjects the cavern wall to Ref. [49]. ...
To reduce effects from anthropogenically induced climate change renewable energy systems are being implemented at an accelerated rate, the UKs wind capacity alone is set to more than double by 2030. However, the intermittency associated with these systems presents a challenge to their effective implementation. This is estimated to lead to the curtailment of up to 7.72 TWh by 2030. Through electrolysis, this surplus can be stored chemically in the form of hydrogen to contribute to the 15 TWh required by 2050. The low density of hydrogen constrains above ground utility-scale storage systems and thus leads to exploration of the subsurface.
This literature review describes the challenges and barriers, geological criteria and geographical availability of all utility-scale hydrogen storage technologies with a unique UK perspective. This is furthered by discussion of current research (primarily numerical models), with particular attention to porous storage as geographical constraints will necessitate its deployment within the UK. Finally, avenues of research which could further current understanding are discussed.
... Therefore, on the one hand, time-dependent thermo-mechanical behavior of salt cavern needs to be investigated in design step and, on the other hand, the geometrical and operational parameters of the cavern are required to be developed by modeling (Ghasemloonia and Butt 2015). To reach a desirable stability and a suitable serviceability of caverns, various design methods have been proposed by researchers during decades so as to operational pressures were limited between a range in which no or less micro-fracturing was permitted (Habibi 2019). However, recently, DeCosta et al. (2020) proposed a new conceptual design method through which a parametric study is performed to select the best relation between flow rate, leaching time, structural stability, and the volume of gas. ...
Stability analysis of salt caverns is a very complicated subject due to the coupled time-dependent thermo-mechanical behavior of salt during leaching and operational phase of the gas storage subjected to the cyclic loading. Because of purely plastic behavior of salt and the relevant convergence during injection and withdrawal, investigation of the salt cavern stability becomes more challenging. The objective of this study is stability analysis of Nasrabad salt cavern by numerical method using a comprehensive software entitled LOCAS having capability to model the complex time-dependent thermo-mechanical behavior of salt under cyclic loading of natural gas pressure. Measurement of geomechanical properties of salt is also the important requirement for modelling. First, geomechanical properties of Nasrabad salt including uniaxial and tri-axial compressive strength, tensile strength, uniaxial and tri-axial creep under different temperatures were measured. Thereafter, time-dependent behaviors and parameters of dilatancy criterion of the test results were analyzed by the advanced constitutive models for rock salt to obtain accurate parameters for modeling. Then, long-term stability was analyzed for Nasrabad salt cavern having different shapes, sizes and depths under cyclic loading 3 – 8 MPa as minimum and maximum gas pressures. The results showed that an ellipsoidal cavern having initial volume of 100000m3 at 450m depth by 0.3% creep closure rate per year and volume loss of 0.8% of the initial volume per year as ideal conditions can store 8000000m3 natural gas with working capacity of about 6000000m3.
... Therefore, on the one hand, time-dependent thermo-mechanical behavior of salt cavern needs to be investigated in design step and, on the other hand, the geometrical and operational parameters of the cavern are required to be developed by modeling (Ghasemloonia and Butt 2015). To reach a desirable stability and a suitable serviceability of caverns, various design methods have been proposed by researchers during decades so as to operational pressures were limited between a range in which no or less micro-fracturing was permitted (Habibi 2019). However, recently, DeCosta et al. (2020) proposed a new conceptual design method through which a parametric study is performed to select the best relation between flow rate, leaching time, structural stability, and the volume of gas. ...
Stability analysis of salt caverns is a very complicated subject due to the coupled time-dependent thermo-mechanical behavior of salt during leaching and operational phase of the gas storage subjected to the cyclic loading. Because of purely plastic behavior of salt and the relevant convergence during injection and withdrawal, investigation of the salt cavern stability becomes more challenging. The objective of this study is stability analysis of Nasrabad salt cavern by numerical method using a comprehensive software entitled LOCAS having capability to model the complex time-dependent thermo-mechanical behavior of salt under cyclic loading of natural gas pressure. Measurement of geomechanical properties of salt is also the important requirement for modelling. First, geomechanical properties of Nasrabad salt including uniaxial and tri-axial compressive strength, tensile strength, uniaxial and tri-axial creep under different temperatures were measured. Thereafter, time-dependent behaviors and parameters of dilatancy criterion of the test results were analyzed by the advanced constitutive models for rock salt to obtain accurate parameters for modeling. Then, long-term stability was analyzed for Nasrabad salt cavern having different shapes, sizes, and depths under cyclic loading 3–8 MPa as minimum and maximum gas pressures. The results showed that an ellipsoidal cavern having initial volume of 100,000 m³ at 450 m depth by 0.3% creep closure rate per year and volume loss of 0.8% of the initial volume per year as ideal conditions can store 8,000,000 m³ natural gas with working capacity of about 6,000,000 m³.
... What made this technique conceivable in the first place is the excellent sealing capacity of rock salt due to its naturally low porosity and permeability (Popp and Kern, 1998;Wang et al., 2019). However, underground cavity opening in undisturbed rocks results in the creation of disturbed zones around the underground facility (DeVries et al., 2002(DeVries et al., , 2005Habibi, 2019), where the stress state is far from being isotropic and can present high levels of deviatoric stress (DeVries et al., 2002;Tsang et al., 2005). ...
This paper focuses on the presence of nodules of insoluble materials within salt specimens, and their effect on the volumetric strain measurements and the dilatancy phenomenon. We analyzed experimental results of over 120 conventional triaxial compression tests, and found that in 20% of the cases, the volumetric strain measurements were atypical. We also noted that the natural variability of the specimens can lead to a non-negligible data scattering in the volumetric strain measurements when different specimens are subjected to the same test. This is expected given the small magnitude of those strains, but it occasionally implies that the corresponding specimens are not representative of the volumetric behavior of the studied rock. In order to understand these results, we numerically investigated salt specimens modeled as halite matrices with inclusions of impurities. Simulations of triaxial compression tests on these structures proved that such heterogeneities can induce dilatancy, and their presence can lead to the appearance of tensile zones which is physically translated into a micro-cracking activity. The modeling approach is validated as the patterns displayed in the numerical results are identical to that in the laboratory. It was then employed to explain the observed irregularities in experimental results. We studied the natural variability effect as well and proposed a methodology to overcome the issue of specimen representativity from both deviatoric and volumetric perspectives.
