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A brief history of salt cavern use
Abstract
A brief history of salt cavern use is presented, beginning with the storage of liquid and gas hydrocarbons around five to six decades ago, and continuing to the present. Current main uses of salt caverns worldwide, including storage of hydrocarbons and disposal of wastes, are described. A number of unusual uses, both existing and proposed, are cited. Some problems that have occurred with the use of salt caverns are also noted. Advancements made in salt cavern use are summarized in the conclusion.
... Underground salt caverns have been used over about seven to eight decades [2,44]. The first conception of underground salt cavern used for liquids and gases was reported in Canada in the early 1940s. ...
... The underground salt caverns have also been considered suitable as compressive air energy storages (CAES) [11]. The first symposium on rock salt was held in 1962, and technologies, including the use of sonar, were discussed [33,44]. Stability and tightness are key factors for a salt cavern and were studied for many years [21, 28, 39-41, 43, 54, 59]. ...
... Stability and tightness are key factors for a salt cavern and were studied for many years [21, 28, 39-41, 43, 54, 59]. Large volume loss is a common problem during the operation of salt cavern, e.g., Eminence dome in the USA (with loss of 40%) and Tersanne in France ((with loss of 30%) [3,6,44]. The study of salt cavern in China started in 1999. ...
Recent in situ pressure test indicates that there is a mudstone interlayer with high permeability in the open hole of the underground gas storage (UGS) salt caverns in Jintan, China. The interlayer is called the “micro-leakage interlayer (MLI).” MLI brings a great new challenge for UGSs construction and operation. The stability evaluation is the main research target of this paper. Laboratory tests have been carried out on samples collected from the target formation to determine the mechanical properties. A 3D geomechanical model of the two adjacent caverns with MLI is established based on the geological data and the laboratory test results. The minimum and maximum limit operating pressures are determined as 6 MPa and 18 MPa based on the numerical simulation results of six operating conditions. Two operating conditions (synchronous and asynchronous injection–production) are designed and discussed. The result shows that the MLI has little effect on the stability of the caverns and can be ignored. The stability under the two operating conditions is quite good, suggesting that asynchronous injection–production can be used in the actual operation. This makes the operation more flexible to meet unpredictable situations. The tightness analysis under the two operating conditions will be the subject of future investigations.
... Salt caverns have been used in the field of oil and gas storage for a long time. Canada took a pioneering role in the use of salt caverns for hydrocarbon storage in the early 1940s [26,27]. Subsequently, in 1961, another salt cavern for gas storage was built in the United States using the Morton No. 16 salt cavity in order to store natural gas in Marysville and Michigan [28]. ...
... Although the volume of salt caverns accounts for only 8 Salt caverns have been used in the field of oil and gas storage for a long time. Canada took a pioneering role in the use of salt caverns for hydrocarbon storage in the early 1940s [26,27]. Subsequently, in 1961, another salt cavern for gas storage was built in the United States using the Morton No. 16 salt cavity in order to store natural gas in Marysville and Michigan [28]. ...
Underground salt caverns are widely used in large-scale energy storage, such as natural gas, compressed air, oil, and hydrogen. In order to quickly build large-scale natural gas reserves, an unusual building method was established. The method involves using the existing salt caverns left over from solution mining of salt to build energy storages. In 2007, it was first applied to Jintan Natural Gas Storage of China. Based on this successful project, several existing salt caverns were screened to build energy storages in China. Engineering experience indicates that the key to successful reusing is how to select the most suitable of the numerous available caverns and confirm it. This paper summarizes and reviews relevant theories and testing methods, including: (1) the primary selection principle for using existing salt caverns to build energy storage, (2) the testing method and evaluation theory of tightness of the existing salt cavern, and (3) the typical project case of using the existing salt caverns to build energy storage in China. From the practical application results, the selection principle proposed in this paper can quickly screen available existing salt caverns with energy storage potential, and the brine injection method can effectively evaluate their tightness. It provides a technical roadmap for the subsequent implementation of existing salt cavern utilization projects on a large scale.
... Therefore, such caverns are used extensively for energy storage [3e7] and wastes disposal [8,9]. The storage of natural gas and crude oil are predominant salt cavern applications [10,11]. The global total working gas volume stored in salt caverns is over 28 billion m 3 [12], supplying 28.3 billion m 3 of working gas (the total gas stock minus the cushion gas reserve). ...
... All around the world, thousands of salt caverns in salt domes for hydrocarbon storage are vertical caverns [11]. However, salt domes are scarce and their distributions are limited. ...
Underground salt caverns are used globally for large-scale energy storage. In the thinly bedded rock salt in China, two butted-well horizontal (TWH) caverns, as alternatives for energy storage, are regarded as having better suitability and economy than vertical caverns. However, understandings of the cavern shape development and control methods of TWH-caverns remain insufficient. To overcome these shortcomings with respect to TWH-caverns, we conducted physical simulations of TWH-cavern construction using a high strength steel mold and molded large rock salt specimens. We established a platform for physical simulation of TWH-cavern water-solution construction using the large molded rock salt specimens, so that the construction process is visible and easily observed. Six groups of physical simulations of TWH-cavern construction were designed and implemented. The variables which affect the cavern outline expansion were investigated and compared, including water injection rate, transferring of injection well, oil blanket, and retreating position of the water outlet. Finally the expansion rules of the cavern outline, and different effects when injecting from an inclined well vs. From a vertical well were explored, as well as an attempt of retreating water outlet. This study provides significant guidance for constructing horizontal caverns for energy storage in thinly bedded rock salt.
... Underground salt caverns have been used for decades to store hydrocarbons (Bays 1962;Fokker 1995;Thoms and Gehle 2000). In the energy transition context, their design is still a relevant issue. ...
... The simulated cavern is based on data from existing gas storage caverns [see, for instance, (Thoms and Gehle 2000;Bérest et al. 2012)]. It does not represent one existing cavern in particular but its characteristics were chosen using in situ data in terms of depth, shape, volume, and operating conditions. ...
This paper presents a new approach for salt cavern design, based on the use of the onset of dilatancy as a design threshold. In the proposed approach, a rheological model that includes dilatancy at the constitutive level is developed, and a strain-based dilatancy criterion is defined. As compared to classical design methods that consist in simulating cavern behavior through creep laws (fitted on long-term tests) and then using a criterion (derived from short-terms tests or experience) to determine the stability of the excavation, the proposed approach is consistent both with short- and long-term conditions. The new strain-based dilatancy criterion is compared to a stress-based dilatancy criterion through numerical simulations of salt caverns under cyclic loading conditions. The dilatancy zones predicted by the strain-based criterion are larger than the ones predicted by the stress-based criteria, which is conservative yet constructive for design purposes.
... For more than half a century, salt caverns have been regarded as one of the most important subsurface energy storage methods in the world for >50 years [9]. In the 1940s, Canada built the first salt rock storage reservoir for natural gas [10]. Subsequently, the United States, France, Germany, and other nations have since each attempted to store gas in salt mound [11]. ...
In China, salt cavern gas storages are typically constructed in strata of complicated bedded salt rock, which are made up of numerous thin interlayers and salt rock that contains impurity. The long-term stability and safety assessment of underground caverns is crucial for the safe operation of gas storage in this type of complicated strata. In order to more accurately describe the long-term creep characteristics of salt rock and mudstone, the fractional derivative creep-damage (FDCD) constitutive model is used in this work. Earlier researches have also demonstrated the advantages of this model when it comes to long-term creep. Pingdingshan (PDS)'s shape and dimensions are developed in accordance with the formation conditions, and a three-dimensional geological model is built according to the designed gas storage. The long-term stability and safety of gas storage under various constant operating internal gas pressures (IGP), cyclic IGP, and gas extraction rates are investigated based on the comprehensive evaluation criteria including deformation, volume shrinkage rate, safety factor, and plastic zone. The results reveal that when the constant operating IGP is 13 MPa, and the cyclic IGP is 13-27 MPa PDS gas storage has good long-term stability and safety. While the plastic zone of mudstone interlayer is still presented at the top and bottom of the gas storage at IGP = 13-27 MPa, and the plastic zone is more pronounced at low constant and cyclic IGP levels. The safety factor of rock mass close to the sidewalls is always <1.5 throughout the long-term operation of gas storage, which makes it more vulnerable to dilatancy failure and requires attention. The deformation and volume shrinkage of gas storage are greatly impacted by the gas extraction rate, and the evolution characteristics of 4 indicators under various gas extraction rates are provided. This study provides a crucial reference for the design of gas storage in China's intricate salt rock regions with multiple interlayers in the PDS region.
... Additionally, rock salt is ductile and, if the stress state is propitious, it has the potential to seal and heal technically induced fractures (Hou 2003;Hunsche & Hampel 1999). Because of these favorable characteristics, leached salt caverns have been used since the late 1940s to store hydrocarbons and other substances such as helium, compressed air and wastes (Thoms & Gehle 2000). Large-scale hydrogen storage in salt caverns is being considered in several countries worldwide in the context of the energy transition (Tarkowski 2019). ...
... In the third phase, gravity differentiation results in a low brine concentration in the upper part of the cavern and a high brine concentration in the lower part of the cavern [9]. However, the oil-blanket controls upper cavern dissolution, and during this period, the depth of the leaching tubing is continuously adjusted, with the cavern finally reaching its desired shape [10]. ...
In recent decades, creep in salt cavern Underground Gas Storage (UGS) has caused accidents at different locations around the world. Most of them were caused by volume shrinkage of salt caverns. In order to analyze the stability condition of the two-well-horizontal (TWH) salt cavern more realistically, we apply the TWHSMC V2.0 code that was calculated using the cavern geometry, and we used FLAC3D to study the stability of the cavern. Our results show that for a TWH salt cavern: 1) the optimal maximum and minimum operating pressures are 23 MPa and 16 MPa, 2) that the UGS remains stable under static pressure and for a long period of time, and 3) that the horizontal displacement of the cavern is relatively small compared to the vertical displacement. More cycles per unit time and a shorter continuous operation of low-pressure time, result in a smaller volume shrinkage rate and thus less cavern deformation. The recommended casing shoe height should be at least 12 m from the top of the cavern.
... Series: Earth and Environmental Science 570 (2020) 062020 IOP Publishing doi:10.1088/1755-1315/570/6/062020 3 realized by Britain, which stored crude oil in salt caverns during the Suez Canal crisis in the 1950s [5]. The world's first salt-cave gas storage was built in the Soviet Union in 1959. ...
Renewable energy holds significant promise of replacing the conventional energy sources. However, the wind and solar energy exhibit the obvious discontinuity, instability, and uncontrollability problems. Redox flow batteries are a novel energy technology, whose most appealing features are high efficiency, long life, and reduced environmental impact. Salt rock has low porosity and permeability, and can self-heal from damage. A salt chamber after water-dissolution is considered as an excellent geological body for energy storage. This study reviews in detail the current worldwide status of salt cavern utilization. Drawing on the salt-carven oil and gas storage technology, the feasibility of storing electrolytes in salt caverns is analyzed considering the physical characteristics of salt rock deposits, and economic and environmental factors. Two medium salt caverns in Jiangsu Province were selected and used as a case study for storage for the all-vanadium flow batteries. The working principle of salt cavern is introduced, and the efficiency of energy storage of the entire system is approximately calculated. Based on the assessment of the existing salt caverns in China, it has been found that using salt caves for electrolyte storage can solve the current problems of disposing old battery electrolyte.
... Salt rock is a type of soft rock, which have many differences in rock mechanics with common rocks [16][17][18][19][20][21]. Due to the excellent petrophysical properties of rock salt [22][23][24][25][26], such as small porosity, extremely low permeability, self-healing capacity, and water solution character, salt caverns leached in underground salt formations are regarded as a safe and economic way for hydrocarbon (oil, gas) storage [27,28]. Salt caverns also have other diversity of storage applications, such as used for the compressed air energy storage [29], hydrogen storage [30,31], as well as the disposal site for chemical and radioactive https://doi.org/10.1016/j.est.2020.101669 ...
In the thinly bedded salt rocks, the roofs of salt cavern gas storage may have different lithology, some cavern roofs of these caverns may be damaged and lose tightness. Thus it is significant to study the characteristic of the gas leakage through the cavern roof of the gas storage cavern in bedded salt rocks. To approach such a goal, the gas leakage through a cavern roof and the induced collapse are investigated in this study. At first, the salt cavern of ZJ-block of Huai'an salt mine is selected as the potential gas storage site, which has a roof consisting of salt rock, a thin gypsum layer, and thick argillaceous siltstone. And then, the porosity and permeability of rock samples of the roof strata are measured in the laboratory. Thirdly, a numerical simulation model is established based on the geo-conditions of the ZJ-block. The gas seepage and cavern tightness under three different cavern roof conditions are simulated and analyzed. The results show that, if the cavern roof is integral, the main gas seepage channels of the cavern are the interlayers, and the tightness of gas storage salt cavern is satisfactory once the permeability of interlayers is around 10⁻¹⁷ m² or lower. After the salt rock layer of the roof is damaged and a partial gypsum layer is exposed, the gas leakage amount can increase about one order of magnitude. But the seepage rate and pore pressure both change slowly in the roof. Thus the operators have sufficient time to survey the accidents and transfer the gas away. However, after the thin gypsum layer is damaged and results in the exposure of argillaceous siltstone, the gas seepage sharply increases. Including the leakage amount, the seepage range, and the pore pressure are all increased much than that of the above two conditions. Due to the serious consequence of storage safety, this condition should be absolutely avoided. To ensure the roof safety and tightness of gas storage, it is suggested that the reasonable construction of a cavern roof is the prerequisite, and the internal pressure monitoring, as well as sonar measuring, should be engaged regularly during the operation period.
... For example, Evans [34], of the UK Geology Research Association, briefly described and analyzed many accidents that have happened in underground energy storage facilities (including storage caverns in salt rock). Be´rest and Brouard [35], Thoms and Gehle [36], Ehgartner et al. [37], and Cowley [38] analyzed fire and explosion accidents of the storage caverns in salt rock. In Ref. [39], the risk of the salt cavern oil/gas storage was assessed by the risk matrix analysis, and the salt cavern oil/ gas storage's probability of tremendous accident, risk grade, accident types and the main accident causes was analyzed. ...
In this study, a systematic and comprehensive methodology to assess the operating reliability of the underground gas storage in multiple salt caverns is developed, and both the thermal-hydraulic characteristic and the operating states uncertainties of the gas storage are considered. This method consists of the thermal-hydraulic analysis of the gas storage, the unit failure probability estimation, and the operating reliability assessment of the entire system. Firstly, the thermal-hydraulic analysis of the underground gas storage during the gas injection and production cycle is undertaken, which is used to obtain the operating parameters and determine whether the operational constraints are met. Thereafter, the failure criterions and the corresponding limit state functions of the salt cavern and gas injection-production well are established to calculate their failure probabilities. Finally, the reliability calculation algorithm of the k-out-of-n: G system is employed to assess the operating reliability of the gas storage in multiple caverns.
Furthermore, a numerical example based on a real underground gas storage is applied to confirm the feasibility of the methodology, and the ability of the gas storage to perform the specified gas injection and production function is evaluated. The assessment results indicate that the operation scheme about the number of caverns selected to perform the required task, has a significant impact on the operating reliability of the underground gas storage.
... In the 1960s, salt caverns were firstly used in Canada to store liquid and gas hydrocarbon. American had begun to use salt caverns for natural gas storage in the past fifty years (Thoms and Gehle 2000). As of the end of 2016, the working gas volume stored in salt caverns exceeded 140 9 10 8 m 3 in Germany (GIE EU 2018). ...
The deformation and strength characteristics of rock salt is significant for the safety of hydrocarbon energy (oil, gas) storage in salt caverns. To overcome the problem of determining the peak strength by simultaneously considering the dilatancy characteristics of salt rock, compression experiments were carried out on Pingdingshan salt rock under different confining pressures. The results shew that the uniaxial experiment of salt rock presented a brittle failure, but the presence of impurities improved the strength of samples. After the confining stress reached a "Transition confining pressure"—6.55 MPa, which was determined by using a chart method, the strength of salt rock increased greatly and behaved a strong strain hardening phenomenon. An empirical method to determine the "transition confining pressure" was put forward, and it was also suggested that the minimum operating pressure in a gas storage salt cavern should be higher than this value. The experiments under different confining pressures indicated that the higher the confining pressure was, the more hysteretic the dilatancy occurred. Based on this result, a method to determine the peak strength of salt rock based on a certain axial strain value (6%) or the initial point of dilatancy was proposed. Then the peak strength of the salt rock samples in this study was calculated to verify the feasibility of this method. This study provided the determination methods for the "transition confining pressure" and the peak strength for salt rock, which was a reference for the evaluation and operation of the gas storage salt caverns.
... Oil and gas are stored in underground spaces created by water solution mining of deep salt deposits. This method is widely used in several countries including the United States, Germany, France, and Canada (Thoms and Gehle 2000). It is also an important measure of China's underground energy reserves (Zhang et al. 2017a). ...
In the study, a self-developed Split Hopkinson pressure bar apparatus with triaxial confining pressure was used to examine the dynamic compression property of salt rock under confining pressures of 5, 15, and 25 MPa. To examine the dynamic properties of salt rock, Yingcheng salt rock from Hubei province in China was considered. Dynamic stress–strain curves of salt rock under different confining pressures and strain rates were obtained. The results indicated that the peak stress and ductility of salt rock increased with increase in the strain rate although the strain rate strengthening effect of the salt rock was not evident with increase in the confining pressure. The dynamic properties and disintegration characteristics were investigated on the basis of the energy dissipation principle. The energy delivery and transformation in the entire experimental process were analyzed in detail. Under the same confining pressure, the hardening effect of the salt rock was more evident with increase in the incident energy, and this can be explained by the decrease in the energy transmission/absorption rate when the reflectance rate increased. Contrary to the plastic damage characteristics under quasi-static triaxial compression, the salt rock exhibited evident brittle fracture characteristics under dynamic compressive loading. The peak stress of the salt rock revealed different trends with the increase in energy absorption under different confining pressures. Increased energy absorption and higher peak stress were observed under low confining pressure. However, the peak stress significantly decreased with increase in the energy absorption under high confining pressure.
... The U.S. stores crude oil in sixty-two caverns located at four different sites in Texas and Louisiana, which accounts for 90% of its oil reserves. 6,7 About 42% of Germany's oil is stored in underground salt caverns. Countries such as France, Canada, Mexico and Morocco have also built SPR salt caverns to protect their national energy securities. ...
Using salt caverns for underground strategic petroleum reserve (SPR) is the most popular storage method in the world due to its high security and economy. The rock salt resources in China are mainly bedded salt, containing many mudstone interlayers. In this paper, pH test and total acid number (TAN) tests are carried out to determine the different degradation mechanisms caused by brine-mudstone and oil-mudstone interactions. Uniaxial and triaxial compression tests and permeability tests were carried out to determine the mechanical and permeability parameters of the mudstone interlayers under brine and crude oil immersions. Results show that the thermochemical sulfate reduction (TSR) will not occur during the crude oil storage. The reaction between the anhydrite and the naphthenic acid is the major reason that causes damage to the mudstone interlayers. Both the crude oil and brine can cause damage to the mudstone interlayers, but the damage caused by brine to the mudstone interlayers is much greater than that caused by crude oil because of their different reaction mechanisms. Due to the plugging effect by the asphaltene and resin present in crude oil, the permeability of the samples decreases 67.5% after they have been immersed in crude oil for 30 days, even though the rock damage is still accumulating. This property is beneficial for the SPR salt caverns, to keep good tightness.
... A l'étranger, la problématique de l'abandon des cavités salines suscite également de nombreuses études. Citons par exemple les expérimentations menées dans la région d'Etzel, au Nord-Ouest de l'Allemagne [Thoms et al., 2000 ;Schweinsberg et al., 2004, Staudmeister et al., 1998Rokahr et al., 2000 ;Hauck et al., 2001]. Certains résultats issus de ces travaux seront exploités au § 6.3. ...
The abandonment, in the medium or long term, of underground storage of natural gas, liquid or liquefied hydrocarbons or industrial chemicals will become a subject of growing concern in the coming years. Most of the underground storage facilities are still operating in France, but concrete cases of a "stop work declaration" are now presented to the State's training departments and it is appropriate for the public authorities to set up rules of good practice to ensure that the safety of people and property, as well as the protection of the environment, will be ensured over the long term around abandoned sites. In order to assist the Administration in this process, this report presents a synthesis of knowledge and practices regarding the abandonment of underground storage facilities. The document is intended primarily as a collection of information and references rather general, from which the reader may possibly deepen certain points in more detail. The document seeks to address all issues related to abandonment, including: regulatory aspects (both in France and abroad); description of the technical operations performed during the abandonment of a storage; summary of accident cases constituting interesting feedback on the issue of abandonment; identification of major hazards or impacts in the context of abandonment of underground storage; presentation of methods and bibliographic elements that can assist in the evaluation of these hazards; identification of monitoring techniques that could be used during and after abandonment of underground storage. The document covers the different types of storage, namely storage in porous media (so-called in aquifers), in salt cavities (made by dissolving salt) or in mined cavities. It is intended for all stakeholders in underground storage facilities, be it the central administration, the state training departments, the operators, the experts, the design offices or local authorities.
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L’abandon, à moyen ou long terme, des stockages souterrains de gaz naturel, d'hydrocarbures liquides ou liquéfiés ou de produits chimiques à destination industrielle, va devenir un sujet de préoccupation croissante dans les années à venir. La plupart des stockages souterrains sont encore en phase d’exploitation en France mais des cas concrets de « déclaration d’arrêt des travaux » sont désormais présentés aux services instructeurs de l’Etat et il convient, pour les pouvoirs publics, de mettre en place des règles de bonnes pratiques permettant de garantir que la sécurité des personnes et des biens, ainsi que la protection de l’environnement, seront assurés sur le long terme autour des sites abandonnés. Afin d’aider l’Administration dans cette démarche, ce rapport présente une synthèse des connaissances et des pratiques en matière d'abandon des stockages souterrains. Le document se veut avant tout un recueil d’informations et de références assez général, à partir desquelles le lecteur pourra éventuellement approfondir certains points plus en détails. Le document s’attache à aborder l'ensemble des problématiques liées à l'abandon, notamment : aspects réglementaires (aussi bien en France qu’à l'étranger) ; description des opérations techniques réalisées lors de l’abandon d’un stockage ; récapitulatif des cas d'accidents constituant un retour d’expérience intéressant pour la problématique de l'abandon ; identification des principaux aléas ou impacts dans le contexte de l'abandon d'un stockage souterrain ; présentation de méthodes et d’éléments bibliographiques pouvant aider à l'évaluation de ces aléas ; recensement des techniques de surveillance qui pourraient être employées pendant et après l'abandon d’un stockage souterrain. Le document couvre les différents types de stockages, à savoir les stockages en milieux poreux (dits en aquifères), en cavités salines (réalisées par dissolution du sel) ou en cavités minées. Il s’adresse à l’ensemble des parties prenantes des stockages souterrains, que ce soit l’Administration centrale, les services instructeurs de l’Etat, les exploitants, les experts, les bureaux d’étude ou bien encore les collectivités locales.
... Underground solution mined salt caverns such as natural gas storage have been constructed and operated successfully in many parts of the world (Thoms and Gehle, 2000), e.g., currently there are eleven UGS in China in operation, with designed working gas volume of 18 billion m 3 (approximately 637119.9 MMcf) (Ding, 2015). ...
... Seepage inevitably occurs in the process of storage for improper assessment, sometimes causing severe accidents (Wang et al. 2015). For instance, liquefied petroleum gas leakage from porous soil occurred in the Barbers' Hill dome in 1980, Texas, and caused a severe explosion (Thoms and Gehle 2000;Evans 2009). A similar accident happened again at the same site five years later. ...
The permeability of the surrounding rock is a critical parameter for the designing and assessment of radioactive waste disposal repositories in the rock salt. Generally, in the locations that are chosen for radioactive waste storage, the bedded rock salt is a sedimentary rock that contains NaCl and Na2SO4. Most likely, there are also layers of gypsum \(( {\text{CaSO}}_{ 4} \cdot 2 {\text{H}}_{ 2} {\text{O)}}\) present in the salt deposit. Radioactive wastes emit a large amount of heat and hydrogen during the process of disposal, which may result in thermal damage of the surrounding rocks and cause a great change in their permeability and tightness. Therefore, it is necessary to investigate the permeability evolution of the gypsum interlayer under high temperature and high pressure in order to evaluate the tightness and security of the nuclear waste repositories in bedded rock salt. In this study, a self-designed rock triaxial testing system by which high temperature and pressure can be applied is used; the μCT225kVFCB micro-CT system is also employed to investigate the permeability and microstructure of gypsum specimens under a constant hydrostatic pressure of 25 MPa, an increasing temperature (ranging from 20 to 650 °C), and a variable inlet gas pressure (1, 2, 4, 6 MPa). The experimental results show: (a) the maximum permeability measured during the whole experiment is less than 10⁻¹⁷ m², which indicates that the gypsum interlayer has low permeability under high temperature and pressure that meet the requirements for radioactive waste repository. (b) Under the same temperature, the permeability of the gypsum specimen decreases at the beginning and then increases as the pore pressure elevates. When the inlet gas pressure is between 0 and 2 MPa, the Klinkenberg effect is very pronounced. Then, as the pore pressure increases, the movement behavior of gas molecules gradually changes from free motion to forced directional motion. So the role of free movement of gas molecules gradually reduced, which eventually leads to a decrease in permeability. When the inlet gas pressure is between 2 and 6 MPa, the Klinkenberg effect dribbles away, and the gas flow gradually obeys to the Darcy’s law. Hence, the permeability increased with the increase in inlet gas pressure. (c) The curve of permeability versus temperature is divided into five stages based on its gradient. In the temperature range of 20–100 °C, the permeability of gypsum decreased slowly when the temperature decreased. From 100 to 200 °C, the permeability of gypsum increased dramatically when the temperature increased. However, a dramatic increase in permeability was observed from 200 to 450 °C. Subsequently, in the temperature range of 450–550 °C, due to closure of pores and fractures, the permeability of the specimens slowly lessened when the temperature increased. From 550 to 650 °C, the permeability of gypsum slightly increased when the temperature increased; (d) the micro-cracks and porosity obtained from the CT images show a high degree of consistency to the permeability evolution; (e) when compared to the permeability evolutions of sandstone, granite, and lignite, gypsum exhibits a stable evolution trend of permeability and has a much greater threshold temperature when its permeability increases sharply. The results of the paper may provide essential and valuable references for the design and construction of high-level radioactive wastes repository in bedded salt rock containing gypsum interlayers.
... Due to the advantages of salt caverns, many countries try to use them to build gas storages, oil storages, hazardous waste underground repositories, compressed air energy storages, and so on. (Sehalge, 1993; Thomas, 2000; Xu Xinqiao, 2006). Compared with the thick salt formed by marine deposit in other countries, salt rock in China is layered structure formed by lacustrine deposit, with the characteristics of small thickness salt bed, multiple inter-beds mudstone and shallow buried deep, and so on(YANG Chun-he, 2005Chun-he, , 2009 YANG Qiang, 2011). ...
In order to analyse the geological characteristics of salt rock and stability of salt caverns, rough three-dimensional (3D) models of salt rock stratum and the 3D models of salt caverns on study areas are built by 3D GIS spatial modeling technique. During implementing, multi-source data, such as basic geographic data, DEM, geological plane map, geological section map, engineering geological data, and sonar data are used. In this study, the 3D spatial analyzing and calculation methods, such as 3D GIS intersection detection method in three-dimensional space, Boolean operations between three-dimensional space entities, three-dimensional space grid discretization, are used to build 3D models on wall rock of salt caverns. Our methods can provide effective calculation models for numerical simulation and analysis of the creep characteristics of wall rock in salt caverns.
... For instance, early engineering studies of rock salt were driven largely by the need to design safe salt mines [2]. Then, it was applied into oil or hydrocarbon gas storage [4], and even it was considered to have the possibility to host a deep geological repository for radioactive, high-level waste from nuclear facilities [5], such as Waste Isolation Pilot Plant of USA [6]. Based on the economic and environment-friendly importance, in order to provide a scientific basis for proper stability evaluation and safe design, construction and operation, it's necessary for us to study deeply on halite rocks. ...
A two-dimensional gain-based lattice approach, is developed here, driven by the needs for modelling strategy of rock salt (halite). In this scheme, considering crystalline micro-structure, halite is discretized into polygonal grains by smooth joint logic, in which mass nodes with micro-rotation are connected by springs. The contacts between grains are in a point-to-point manner, which can avoid complex contact definition (point-to-edge, or edge to edge, etc.) in classical numerical simulations. Breakage and creation of interactions in dynamic spring network is applied to implement the dislocation and diffusion within grains in addition to crystal plasticity.
Brazilian tensile test, unconfined and triaxial compression tests are presented for a guideline of parameter identification and a consistent simulation set-up. Relatively comparable results including brittle-ductile transition could be reproduced, revealing the potential to study and quantify the interplays of mechanical deterioration of halite.
... Evans briefly introduced and summarized different kinds of accidents happened for underground energy storage caverns in rock salt. Ehgartner et al. (1998), Thoms andGehle (2000), B erest andBrouard (2003) and Cowley (2008) analyzed the fire explosion accidents of storage caverns in rock salt, emphasizing accident causes on which agreement had been reached. They pointed out that the underground storage accident was inevitable though salt cavities as the reservoirs were more stable than the ground structures. ...
... North America and several European countries. Storage of crude oil reportedly occurred first in England, also in the early 1950s, during the 'Suez Crisis' [13]. ...
The storage of petroleum products above ground surface has many constraints and limitations. A viable alternative is to excavate large underground spaces in rock to provide a safer way for oil storage. Soft rock formations such as salt domes provide suitable conditions from environmental and operational aspects. The potential for high volume storage and low permeability are among advantages of oil storage in caverns excavated in salt rocks. The complicated shape of oil storage caverns, complex behavior of salt rock, and boundary conditions associated with large underground openings are major challenges in the design of salt caverns excavated for oil storage purposes. In this study, the deformation mechanism and stability of salt caverns were investigated. A comprehensive 3D numerical study was carried out to investigate the effects of cavern size and depth, salt rock deformation modulus, and ground in-situ stress regime on the behavior of large salt caverns. The stress field and deformation mechanisms were studied numerically aiming at shedding lights into the design aspects of salt caverns for oil storage. The analysis results show that the cavern safety factor is reduced as a function of cavern depth and storage volume. Also, with decrease in k (ratio of horizontal to vertical in-situ stress), the stability of salt caverns will increase; however, with increase in salt rock young modulus, the sensitivity of cavern stability to k ratio is reduced. Copyright
... Utilizing existing underground space, such as coal and salt mines where mining has been completed, to store gas/oil has a long history throughout the world. In Europe, hydrocarbon storage in abandoned salt caverns has been practiced since the early 1950s [30]. Examples include the Manosque facility in France and the Etzel salt dome near Wilhemshaven, Germany, which has been used since 1971 for crude oil storage. ...
In China, the storage of hydrocarbon energies is extremely insufficient partially due to the lack of storage space, but on the other side the existence of a large number of abandoned salt caverns poses a serious threat to safety and geological environments. Some of these caverns, defined as abandoned caverns under adverse geological conditions (AGC), are expected to store hydrocarbon energies (natural gas or crude oil) to reduce the risk of potential disasters and simultaneously support the national strategic energy reserve of China. Herein, a series of investigations primarily related to the tightness and suitability of the caverns under AGC is performed. Laboratory measurements to determine the physical and mechanical properties as well as porosity and permeability of bedded salt cores from a near target cavern are implemented to determine the petro-mechanical properties and basic parameters for further study. The results show that the mechanical properties of the bedded rock salts are satisfactory for the stability of caverns. The interface between the salt and interlayers exhibits mechanical properties that are between those of rock salt and interlayers and in particular is not a weak zone. The silty mudstone interlayers have relatively high porosity and permeability, likely due to their low content of clay minerals and the presence of halite-filled cracks. The conditions for evaluating the tightness and suitability of a cavern for storing hydrocarbons are proposed, including “No tensile stress,” “Factor of Safety” and “A threshold of leakage amount”. Three-dimensional numerical geomechanical models are developed to indicate how gas seepage evolves around the caverns. The results show that the permeability of the interlayers is a key factor in influencing gas seepage in the vicinity of the caverns and that interlayers form primary channels for gas migration. By evaluating the fluid seepage around the cavern by the above conditions, the upper-threshold permeability of the interlayers is suggested to be no more than 10−16–10−17 m2 to guarantee tightness when storing natural gas and no more than 10−16 m2 when storing oil. In principle, this work provides references for alternate uses of abandoned caverns for hydrocarbon storage under adverse geological conditions.
... Consequently, the required storage space for running the turbine generators can not be provided. Evidences of large losses of storage space were represented in Thomas and Gehle (2000) and Bérest and Brouard (2003). Hereupon, the deformation of the cavity in the long term should be evaluated and restricted in a manner that may not endanger the serviceability of the storage plant. ...
The fluctuating nature of renewable energy sources can be managed by storing the surplus of electrical energy in an appropriate reservoir. The excess electricity available during o�-peak periods of consumption may use to compress air or electrolyze Hydrogen. Afterwards the pressurized gas is stored in the rock salt cavities and discharge to compensate the shortage of energy when required. During this process, the rock salt surrounding the cavern undergoes thermo-mechanical cyclic loading. In order to achieve a stable geotechnical design, the stress-strain response of rock salt under such loading condition have to be identi�ed and predicted. Investigation of a rock salt cavern behavior under such loading is the main focus of this study. To accomplish this, a comprehensive study using three concepts of geotechnical engineering, i.e., constitutive modeling, numerical analysis and experimental investigation is conducted. A triaxial experimental set up is developed to supplement the knowledge of cyclic thermo-mechanical behavior of rock salt. The imposed boundary conditions in the experimental setup are assumed to be similar to the stress state obtained from a full-scale numerical simulation. The computational
model relies primarily on the governing constitutive model for predicting the behavior of rock salt cavity. Hence, a sophisticated elasto-viscoplastic creep constitutive model is developed to take into account the dilatancy and
damage progress, as well as the temperature e�ects. The contributed input parameters in the constitutive model are calibrated using the experimental measurements. In the following, the initial numerical simulation is modi�ed based on the calibrated constitutive model.
... Due to its great physical and mechanical features such as densification, self-healing performance and sound plastic deformation capacity, salt rock is internationally regarded as the ideal medium for storing oil and natural gas, handling the radioactive nuclear waste and storing compressed air energy [1]. Scientists and engineers have spent more than 50 years in studying the usage of salt caverns, and the study on natural gas storage in salt rock in China was also launched over a decade. ...
The high cost and serious pollution of salt cavern construction (SCC) with fresh water (FW) under oil blanket (OB) poses a major challenge to the development of salt cavern energy storage, and it is of great significance for clean brine mining and efficient SCC to replace FW with light brine (LB) as well as OB with gas blanket (GB). However, the expansion and control of cavern shape after replacement remains unclear, and it also needs to be clarified of the feasibility of SCC with LB. Therefore, the experimental and theoretical research on the physical simulation of SCC with LB under GB was carried out. Firstly, the dissolution test of salt rock in brine was performed, and the effect of brine concentration on the dissolution rate of salt rock was investigated, which provides foundation for the brine preparation of the physical simulation and on-site SCC. Then, based on dimensional analysis and similarity theory, a visual physical simulation platform of SCC under GB was established and five groups of physical simulation experiments were carried out. The effects of tube lifting method and circulation mode on the concentration of withdrawn brine and cavern shape were explored. The relationship between lateral dissolution angle and the effective volume of salt cavern energy storage were analyzed, and the measures and suggestions of controlling lateral dissolution angle and GB were proposed. Finally, the techno-economic analysis of SCC with FW and LB under GB was carried out, which shows that SCC with LB under GB possesses lower cost and better environmental protection. This research can serve as a basis for promoting clean and efficient brine mining and SCC.
Worldwide vast experience exists, dating back to 1915, for liquid and gaseous hydrocarbons storage deep underground in geological strata/traps. Storage options include salt caverns, porous rock (depleted hydrocarbon fields or saline aquifers), abandoned mines and mined (unlined or lined) rock caverns, which offer opportunities for compressed air energy storage (CAES). Underground storage presents a number of benefits, notably very large volumes of gas (including air) stored at high pressures (up to 200 MPa), a small footprint with low environmental impact and considerable protection against external influences. CAES plants using solution‐mined salt caverns have operated commercially since 1978 (Huntorf, Germany) and 1991 (McIntosh, Alabama, USA). Despite many studies, proposals and tests in most underground storage types since the 1970s, no further commercial plant was commissioned until 2019 with an ACAES plant at Goderich (Ontario, Canada), utilising a former brine cavern. The development and increasing integration of inherently intermittent renewable energy sources into the electricity grid means that CAES is once again being considered to provide rapid response, bulk energy storage, load‐levelling and grid‐scale support. Various CAES test types have commenced in salt caverns, tunnels and areas of abandoned mines. Options for geological storage, CAES development to date and some key considerations are briefly reviewed.
Compared with vertical storage, horizontal storage in bedded salt rock deposits is reasonable and scientific for large-capacity gas storage and for avoiding the risk of interlayer and interfacial oil and gas leaks. The single-well retreating horizontal (SWRH) leaching method is introduced in this paper. After calculating similarity ratios, a physical similarity simulation experiment was conducted for inferring the cavern shape. A numerical model was developed based on the inferred cavern shape, and the stability of the SWRH cavern was analysed. Reasonable values of the cycle frequency and the roof and floor salt layers’ thicknesses were determined. The effects of the pillar width and asynchronous internal gas pressure between adjacent caverns were analysed. The results show that the SWRH cavern satisfies the safety requirements of bedded salt rock districts over the entire design lifetime. A cyclic frequency that is too low and asynchronous internal gas pressure are not conducive to the stability and reliability of the cavern. To ensure stability, the thicknesses of the roof and floor salt rock layers of the horizontal cavern should exceed 16 m and 6 m, respectively. This study opens new vistas for constructing horizontal gas-storage systems in bedded salt rock.
Power-to-Gas–Oxyfuel, or Electrolysis-Methanation-Oxyfuel, is an advanced concept that addresses some concerns of conventional Power-to-Gas: supply of high-purity CO2, release of greenhouse gases to the atmosphere and fate of the O2 from electrolysis. Due to the intermittent nature of several renewable energy sources, massive storage is needed to balance supply and demand. This paper focuses on the storage phase required for Electrolysis-Methanation-Oxyfuel. Synthetic CH4, O2 and CO2 have to be stored at different times. Due to the high fluid rates and volumes required, salt caverns are potential candidates. While salt caverns have been used for decades to store CH4, storage of CO2 and O2 has not been implemented to date. A generic seasonal scenario with a 200 MW oxyfuel unit is investigated. Numerical modelling that couples cavern thermodynamics with the thermomechanical response of the surrounding rock salt has been performed. The results, although exploratory, show that the caverns would be stable as they respect the criteria commonly used for cavern design. Moreover, combined storage of CO2 and O2 in the same cavern, rather than independent storage, would reduce the number of caverns needed and the likelihood of phase changes, but it would require separation of the two substances at the ground surface.
This article presents a numerical methodology for the simulation of mineral dissolution which couples brine flow, dissolved mineral transport, and cavity evolution. The proposed model considers both (1) the varying density brine flow within the cavity governed by the compressible Navier‐Stokes equations and (2) the evolution of the cavity boundary using a sharp interface model with a physically‐derived dissolution rate equation. The proposed nonlinear multi‐physics model can capture complex flow patterns such as the generation of a vortex in the cavity. The impact of those complex flow patterns on the cavity development can be studied because of the coupling of brine flow and dissolution front movement. The model employs a new strategy to explicitly track the dissolution front, which results in low computational cost for long‐term dissolution simulations. The proposed model is verified through a convergence analysis, showing both spatial and temporal convergence. Numerical simulations of mineral dissolution in horizontal cavities are conducted to investigate the flow velocity, mass fraction of dissolved mineral, cavity shape evolution, and dissolution rate over time. Additionally, a discussion on the effect of Peclet number on mineral dissolution in the cavity is undertaken.
The frequency of occurrences per facility-year, their probabilities, and their uncertainties are critical inputs to hazard and risk management plans for underground storage facilities. We used Bayesian analysis to investigate and quantify the occurrence frequencies at US underground natural gas storage facilities in porous rock and salt-cavern storage facilities. Occurrences for each of the 31 hosting states were classified by storage type, probable cause, and severity.
States having the largest number of occurrences at the lowest, nuisance-group level of severity are California and Pennsylvania (for oil-and-gas storage), Iowa and Illinois (for aquifer storage), and Texas (for salt-cavern storage). Those states having the longest operational experience in natural-gas storage, as inferred by the number of facility-years, are Pennsylvania (for oil-and-gas storage), Illinois (for aquifer storage), and Texas (for salt-cavern storage). Bayesian nuisance-group occurrence frequencies are generally within a two order-of-magnitude range, 10⁻³ to 10⁻¹ (P5–P95), with greater variability for salt-cavern storage. Serious- and catastrophic-group occurrence frequencies for depleted oil-and-gas storages decrease to 10⁻⁴ to 10⁻² for all states except for California, Colorado, and, for aquifer storage, in Illinois, that remain consistent with their nuisance-group levels. The data do not support previous correlations of high occurrence frequencies with well age or construction practices. Instead, anomalously high occurrence frequencies for individual states might be associated with increased testing of wells and related infrastructure, or particular subsurface conditions that might promote location-specific hazards such as corrosion of well components.
Benefiting from its outstanding gas injection-production capability and fully recoverable cushion gas, salt cavern gas storage technology was developed rapidly in recent years. Wangchang salt cave gas storage is characterized by deep burial depth and multiple interlayers. The project of water-soluble cavity construction faces problem of serious tubing and casing bending and deformation. Therefore, development of effective tubing and casing string damage-prevention and risk control method remains an ongoing challenge.
Both theoretical study and field tests are presented in this article. Through field observation, mechanical analysis and production data analysis, it was identified that the main reasons causing tubing and casing bending are liquid-solid coupling instability, interlayer rock impact and smashing, as well as pipe string wear and corrosion. By optimizing the tubing and casing strings design and adjusting production parameters, tubing and casing bending problem could be effectively improved. Besides, remedial measures to deal with bending pipe string were proposed.
Critical destabilizing flow rate of the tubing and casing was calculated under different diameter and wall thickness conditions. Analysis of calculation results showed that the current water injection volume of the Wangchang gas storage well was higher than the critical displacement. It was verified that the liquid-solid coupling instability was the main reason causing tubing and casing bending in the gas storage well. Field data analysis showed that large water injection displacement and high water injection pressure fluctuation was more likely to cause bending and damage of tubing and casing. Technical measures are listed as following: (1) strengthening the steel grade wall thickness of intermediate casing; (2) equipping the central tubing column with a drop connector to optimize the distance between the central tubing shoe and the middle casing shoe; (3) Optimizing the cavity water circulation method to stabilize the water injection pressure and displacement.
The anti-bending technology presented in this study unlocks a critical bottleneck during the salt cave building progress, which is the tubing and casing bending and deformation problem. With the application of this method, efficiency of water-soluble cavity building can be greatly improved. More importantly, this technology might pave a new way for the deep multi-interlayer salt cavern gas storage design.
Underground TWH (Two-well-horizontal) salt caverns are an ideal storage medium for large-scale energy storage, having large usable volumes and high construction efficiency. Different tubing/oil-blanket lifting techniques relate to different solution mining rates and help define cavern geometries based on the previous experience of SWV (Single-well-vertical)-cavern construction. In this study, we present a complete and comprehensive evaluation of the influence of a particular tubing/oil-blanket lifting method on TWH-cavern leaching and geometric shapes. Based on the solution mining numerical simulation original program TWHSMC V2.0 (Two-well-horizontal solution mining cavern V2.0), we carried out a set of numerical simulations, such that the cavern construction process is real-time display and easily recorded. The results demonstrate that with a matching water injection rate, the outlet brine concentration is not sensitive to tubing/oil-blanket lifting. During construction of a horizontal cavern with a volume of 300,000 m3, lifting tubing on both sides simultaneously yields the shortest leaching time (near 307 days). Only lift the tubing on one side will form an asymmetrical cavern, with the height of the cavity near the side being higher than on the opposite side. The lower the frequency of tubing and oil blanket lifting, the smaller the height/length ratio coefficient is, meaning the cavern is closer to the horizontal. Therefore, when constructing TWH-caverns in thinly-bedded rocksalt formations, simultaneously lifting the both sides of tubing and oil-blanket, in addition to a lower lifting rate, are required. This research provides theoretical basis and engineering guidance for TWH-cavern constructing in thinly bedded rocksalt formations.
The salt rock formations in China all contain a certain amount of impurities. It is necessary to study the mechanical performances of salt rock that contains impurities. However, to obtain the salt rock samples that have different types and contents of impurities is difficult. Therefore, man-made salt rock samples containing impurities (sodium sulfate salt rock-SSR and gypsum salt rock-GSR) were prepared to replace the natural salt rock for study. The results show that the density of man-made salt rock was slightly lower than natural ones. And the compactness of SSR samples was suitable while GSR samples were differed slightly, which might be related to the particle size and water absorption of the impurities. Laboratory compression tests were conducted to investigate the influence of impurities on the mechanical performances of the salt rock. The strengths of both SSR and GSR samples decreased with the increase in impurity content. The peak strength of the SSR samples fell straightly, while that of the GSR samples show a parabola-like dropping trend. The elastic modulus of SSR samples beavered enhanced effect and was increased with the increasing content of impurity. And the elastic modulus of GSR samples behaved a parabola-trend decreasing with the impurity content increased. On the evaluation of brittleness characteristics, when the impurity content was at a low level, it had almost no significant effect on the sample's whole ductility. Only at the higher impurity content, the brittleness was increased dramatically, resulting in a rapid rupture of the sample after the peak strength. At last, some discussions about the geological properties of salt mine pointed out the direction of future research. This study revealed the influence of impurities on the mechanical characteristics of salt rocks and could provide a reference for the stability evaluation of natural gas storage caverns in salt formations.
The Yangtze River delta region of China consumes a large amount of natural gas, but the current gas storage facilities of this region can provide only 19.6 × 108 m3 of natural gas for use, which will be far less than the required gas storage volume of 66.8 × 108 m3 in 2030. The reason is due to lacking suitable underground gas storage space. To meet the space demands of underground gas storage (UGS) in the Yangtze River Delta region, the feasibilities of UGS construction in salt formations including depth of mines, thickness of salt strata, distance to pipelines, and geologic safety of the salt mines are evaluated. The representative blocks of Huai’an salt mine and Fengxian salt mine are suggested as potential sites for UGS construction. To promote UGS construction operation quickly and economically, utilizing the existing caverns can be considered firstly. The evaluation indicates that the existing caverns can store about 12.91 × 108 m3 natural gas for UGS with a cavern utilization rate of 30%. To satisfy the space for residual gas storage, the idea of “integration of brine extraction and cavern utilization” is put forward; that is, salt mining enterprises carefully control the usability of newly increased cavern volume during brine extraction. The forecast shows that about 36.9% of the newly increased cavern volume is sufficient to meet the residual cavern demand of UGS to fulfill a gas store volume of 34.3 × 108 m3 in 2030 in the Yangtze River delta. This research provides an effective method to solve the space need for UGS in the Yangtze River delta; simultaneously, it also presents win–win cooperation for the utilization of abandoned caverns and energy storage.
Hydrogen can be produced and stored by electrolysis of water using 100% renewable and clean energy sources (such as solar and wind energy). It can then be converted back into electricity with fuel cells to meet the energy demand. Today, by physical methods, hydrogen is stored as liquid and gas in tanks and underground geological areas (depleted oil and gas, aquifers and salt caverns). One of the important underground gas storage areas are salt caverns. Salt caverns are built in very tight and sealed underground salt rock formation by solution mining method. In this study, the storage of hydrogen in the underground at very large scales was investigated. As a result, salt caverns built in underground salt domes have very high hydrogen storage capacity. Therefore, in the future, we believe that large-scale underground hydrogen storage areas will play an important role in the hydrogen economy as integrated power plants.
Managing produced water from oil and gas wells constitutes a significant portion of the costs of operating a well. In this work, we have designed two different centralized water treatment facilities capable of managing produced water from oil and gas wells in Texas and Louisiana, both of which convert the produced water into the following valuable resources: ten-pound brine and fresh water. The two main designs each use commercially available technology with varying levels of establishment in treating produced water. Both treatment processes remove oil and grease and suspended solids, reduce the divalent ion concentrations, and concentrate the brines to a near-saturation state. The baseline design uses chemical precipitation to remove the divalent ions to meet the reuse specifications, whereas the advanced design uses nanofiltration (NF) membranes to separate divalent ions and uses reverse osmosis (RO) membranes to partially concentrate the brine. Both models use mechanical vapor recompression to concentrate the brine up to NaCl saturation. The baseline process is shown to be cost-effective for low-hardness brines. In the case of high hardness, the chemical precipitation step is cost-prohibitive. We find that NF membranes are a promising alternative to chemical precipitation as a means of separating monovalent and divalent ions.
The reuse of abandoned anhydrite mine-outs has significant potential to reduce the cost and period of construction of crude oil storage facilities and provides a new option for exploiting underground space. Based on a case study of the Anhui Hengtai anhydrite mine located in East China, this study formulated a comprehensive field test program to investigate its tightness and stability and evaluate its feasibility for reuse as crude oil storage. Combining the field tests with laboratory tests, the underlying mechanism of interaction among anhydrite, water, and crude oil was revealed, and the stability and tightness of anhydrite mine-out during the storage of crude oil was evaluated. The results indicate that the anhydrite mine-out has good stability and tightness, which is not affected by the presence of crude oil. Additionally, the anhydrite has negligible effects on the crude oil quality; however, the presence of water reduces the strength of anhydrite rock, which has the potential to affect the stability and tightness of the mine-out. It is concluded that the anhydrite mine-out has the potential to be used as underground crude oil storage space, but the long-term contact between anhydrite rock and water should be avoided. This work is expected to benefit future underground space exploitation through reuse of mine-out.
Salt rock distinguished properties such as creep and tightness make them useful as underground disposal and storage media. This work presents a comprehensive review of salt caverns history and fundamentals of their mechanical behavior. Emphasis is given to salt creep and dilatancy. Following, a methodology for numerical simulation of mechanical behavior of salt caverns is compiled. Transient pressure simulates the constructive period by solution mining and the operation period, during which gas pressure cycles apply. A synthetic case study is performed to demonstrate the methodology. Stress- and strain-based engineering-practical criteria evaluate the global integrity of the cavern. Results show that the cavern wall does not undergo microcracking, remaining tight. This integrity condition is fundamental for underground storage safety. Moreover, strain-related engineering criteria are satisfied in such a way that cavern usability is assured over its lifespan.
The open hole of wellbore may pass through one or several mudstone interlayers during the construction of the salt cavern gas storage in thin interbedded salt mines. Once an interlayer is formed, leakage occurs that will cause the sealing failure of the wellbore. Based on the treatment project executed to ameliorate the wellbore sealing failure in Jintan's (China) salt cavern gas storage, a feasible grouting scheme and plugging evaluation criteria are proposed for similar, leaking interlayers. Combined with geological conditions and leaking types used to establish a radial grouting model, theoretical and numerical solutions for the plugging range are implemented. According to the grouting and plugging parameters used for analyses, the engineering practice indicates that the squeeze ultra-fine grouting can successfully plug this leaking interlayer and the depleted wellbore meets the requirements of storing natural gas that can be used for secondary utilization. The sealing effect mainly depends on the plugging range, which is affected by the grouting parameters, physicochemical properties of grout, and by the fluid–solid coupling. The results show that the viscosity rheology can inhibit grout diffusion, while the grout–rock coupling can promote grout diffusion. Their effects are completely opposite. Finally, the established plugging evaluation criteria can be used to analyze the plugging effect in the short and long-terms, and will have a good theoretical and practical guiding significance for the formation of sealing and gas leakage analysis of underground gas storage (UGS) in the future.
In the current energy transition context, salt caverns are promising for massive energy storage but their design methodology needs to be updated to face the challenge of new operating scenarios. This work proposes a new methodology based on the development of a new rheological model that includes dilatancy and tensile criteria, consistent with the long and short term conditions.
To illustrate the difference between the classical and the new methodologies, fully coupled thermo-mechanical numerical simulations of a spherical cavern, filled with either methane or hydrogen, and the surrounding rock salt are performed under various cycling scenarios. Although the two studied gases show distinctive thermodynamic behaviors, the storage of hydrogen does not raise new issues in terms of the cavern design. Concerning the operation history, in addition to the fact that lowering the cycling amplitude limits the development of dilatancy and tension, it is observed that employing a high cycling rate leaves the dilatancy unchanged but intensifies the tension, both in extent and magnitude, even for a small cycling amplitude.
Wasserstoff ist ein Medium, das aufgrund seiner Erzeugbarkeit allein mit Strom aus Wasser immer wieder das Interesse der Energiewirtschaft weckt. Eine wichtige Komponente auf einem Wasserstoffpfad ist – neben den Einheiten für Erzeugung, Transport und Nutzung – der Speicher. In Abhängigkeit des Einsatzes werden verschiedene Anforderungen an dessen Leistungsfähigkeit gestellt.
استفاده از مغارهای نمکی برای ذخیرهسازی هیدروکربنهای سیال، به عنوان یکی از پیشرفتهترین روشها بکار گرفته میشود. اطمینان از پایداری مغارهای نمکی ذخیره گاز و در عین حال اقتصادی بودن نسبت گاز بیشینه به کمینه، همواره مسئلهای مهم بوده که تاکنون در ایران کمتر به آن پرداخته شده است. با توجه به خصوصیات سنگ نمک و عمق زیاد، تنش عمده در این ناحیه تنش ثقلی است که این تنش به صورت یک فشار خارجی به مغار وارد میشود و سبب کاهش حجم مغار میشود. در مقابل با توجه به اینکه در مغارهای نمکی امکان بکارگیری نگهداریهای مرسوم در مغارهای سنگی مانند شاتکریت، پیچسنگ و غیره وجود ندارد، پایداری مغار تنها با ایجاد یک فشار داخلی (عکسالعمل) به وسیله گاز درون مغار تأمین میشود.این مقاله به بررسی پایداری مغارهای نمکی ذخیره گاز میپردازد. مشخصات هندسی و ژئومکانیکی محدوده مورد مطالعه در جنوب ایران، در نظر گرفته شده و در ادامه پایداری دو مغار کپسولی و هویجی شکل در محیطی پیوسته با استفاده از نرمافزارهای Phase2 و FLAC3D بررسی شده است. با مدلسازی هندسی و مکانیکی این مغارها بر پایه روش اجزاء محدود و تفاضل محدود در عمق مربوط، فشار کمینه (پایه) و بیشینه گاز جهت پایداری مغارها تعیین گردید و بر این اساس نسبت گاز کاری برای مغارها محاسبه شد. مقایسه این نتایج نشان داد که در حالت پایدار مغار هویجی شکل دارای نسبت گاز کاری بیشتری بوده که این مطلب بیانگر صرفه اقتصادی بیشتر این نوع مغار است.
An account is given on the contributions of the U.S. Strategic Petroleum Reserve (SPR) to technology improvements in testing, salt modeling and understanding of underground crude oil storage in salt. Cavern pressure monitoring and modeling capabilities which can enable loss detection of very small volumes of storage oil are highlighted, along with state of the art salt creep modeling, leaching, and cavern design capabilities. Mitigative and diagnostic techniques for fluid leaks are also detailed.
This article describes several accidents that have occurred in underground storage facilities, and reveals some basic safety problems related to mechanical stability, gas and oil tightness, and eruption hazards. Acceptable loss level also is discussed.RésuméCet article décrit plusieurs accidents qui ont eu lieu dans un centre de stockage souterrain et révèle quelques problèmes de sécurité de base se rapportant aux mécanismes de stabilité, aux fuites de gaz ou de pétrole, et aux dangers d'éruption. Un niveau acceptable de perte est aussi discuté.
Some types of oil and gas production and processing wastes contain naturally occurring radioactive materials (NORM). If NORM is present at concentrations above regulatory levels in oil field waste, the waste requires special disposal practices. The existing disposal options for wastes containing NORM are limited and costly. This paper evaluates the legality, technical feasibility, economics, and human health risk of disposing of NORM-contaminated oil field wastes in salt caverns. Cavern disposal of NORM waste is technically feasible and poses a very low human health risk. From a legal perspective, there are no fatal flaws that would prevent a state regulatory agency from approaching cavern disposal of NORM. On the basis of the costs charged by caverns currently used for disposal of nonhazardous oil field waste (NOW), NORM waste disposal caverns could be cost competitive with existing NORM waste disposal methods when regulatory agencies approve the practice.
A relatively large number of salt caverns are used for fluid hydrocarbon storage, including an extensive set of facilities in the Gulf Coast salt domes for the Strategic Petroleum Reserve (SPR) Program. Attention is focused on the SPR caverns because of available histories that detail events involving loss and damage of the hanging string casing. The total number of events is limited, making the database statistically sparse. The occurrence of the events is not evenly distributed, with some facilities, and some caverns, more susceptible than others. While not all of these events could be attributed to impacts from salt falls, many did show the evidence of such impacts. As a result, a study has been completed to analyze the potential for salt falls in the SPR storage caverns. In this process, it was also possible to deduce some of the cavern interior conditions. Storage caverns are very large systems in which many factors could possibly play a part in casing damage. In this study, all of the potentially important factors such as salt dome geology, operational details, and material characteristics were considered, with all being logically evaluated and most being determined as secondary in nature. As a result of the study, it appears that a principal factor in determining a propensity for casing damage from salt falls is the creep and fracture characteristics of salt in individual caverns. In addition the fracture depends strongly upon the concentration of impurity particles in the salt. Although direct observation of cavern conditions is not possible, the average impurity concentration and the accumulation of salt fall material can be determined. When this is done, there is a reasonable correlation between the propensity for a cavern to show casing damage events and accumulation of salt fall material. The accumulation volumes of salt fall material can be extremely large, indicating that only a few of the salt falls are large enough to cause impact damage.
The occurrence of gas in salt mines and caverns has presented some serious problems to facility operators. Salt mines have long experienced sudden, usually unexpected expulsions of gas and salt from a production face, commonly known as outbursts. Outbursts can release over one million cubic feet of methane and fractured salt, and are responsible for the lives of numerous miners and explosions. Equipment, production time, and even entire mines have been lost due to outbursts. An outburst creates a cornucopian shaped hole that can reach heights of several hundred feet. The potential occurrence of outbursts must be factored into mine design and mining methods. In caverns, the occurrence of outbursts and steady infiltration of gas into stored product can effect the quality of the product, particularly over the long-term, and in some cases renders the product unusable as is or difficult to transport. Gas has also been known to collect in the roof traps of caverns resulting in safety and operational concerns. The intent of this paper is to summarize the existing knowledge on gas releases from salt. The compiled information can provide a better understanding of the phenomena and gain insight into the causative mechanisms that, once established, can help mitigate the variety of problems associated with gas releases from salt. Outbursts, as documented in mines, are discussed first. This is followed by a discussion of the relatively slow gas infiltration into stored crude oil, as observed and modeled in the caverns of the US Strategic Petroleum Reserve. A model that predicts outburst pressure kicks in caverns is also discussed.
In order to optimize LPG delivery at the Medford, Okla., plant, consideration was given to various storage methods. This location is on the edge of the Permian salt basin where there is a limited salt thickness. A solution cavity was proposed where the volume was developed essentially in the horizontal direction. Two wells were drilled approximately 400 ft apart and a fracture developed between them. The cavity was dissolved by circulating water between the wells until the volume reached 150,000 bbl. The paper discusses the geological situation and considerations, the fracturing technique, and the solution process.
Bedded and domal salt deposits occur in many states. If salt deposits are thick enough, salt caverns can be formed through solution mining. These caverns are either created incidentally as a result of salt recovery or intentionally to create an underground chamber that can be used for storing hydrocarbon products or compressed air or for disposing of wastes. This report evaluates the suitability, feasibility, and legality of disposing of nonhazardous oil and gas exploration, development, and production wastes (hereafter referred to as oil field wastes, unless otherwise noted) in salt caverns.
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