The Experts below are selected from a list of 2226 Experts worldwide ranked by ideXlab platform
Chunhe Yang - One of the best experts on this subject based on the ideXlab platform.
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Prediction method for calculating the porosity of insoluble sediments for Salt Cavern gas storage applications
Energy, 2021Co-Authors: Xilin Shi, Kai Zhao, Xin Liu, Chunhe YangAbstract:Abstract Many insoluble sediments accumulate at Cavern bottoms during the construction of Salt Caverns located in highly insoluble Salt formations. Before using the void space for gas storage, knowing the porosity is essential for predicting void volume of insoluble sediments. However, most previous studies have focused on construction and operation of Salt Caverns, and insoluble sediments have been largely ignored. In this study, a series of laboratory tests, including screening and porosity tests, are conducted to obtain the particle size distribution and porosity of samples obtained by dissolving the nonSalt interlayers of target Cavern. The results show that the porosity values of the samples decreases with increasing of fractal dimensions and have no relation to the maximum particle size when the fractal dimension is constant. Based on these results, a porosity prediction method is proposed to calculate the porosity of insoluble sediments combined with fractal and packing theories. In this method, the fractal dimension and the compaction index should be controlled within a reasonable range. The accuracy and reliability of this model was studied by calculating the porosity of insoluble sediments in an actual Salt Cavern. This study can provide a reference for evaluating the void volume in insoluble sediments.
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failure analysis for gas storage Salt Cavern by thermo mechanical modelling considering rock Salt creep
Journal of energy storage, 2020Co-Authors: Xiuxiu Miao, Chunhe YangAbstract:Abstract Salt Cavern is ideal vessel for underground gas storage due to the high deliverability. During cyclic gas operations of injection-and-withdrawal, the temperature change in Salt Cavern imposes thermal stress on Cavern wall. The temperature change, together with the pressure change in Salt Cavern, causes the effective stress on Cavern wall to alter, leading to variation of creep rate. In this study, a coupled thermo-mechanical model is proposed for failure analysis of Salt Cavern in rock Salt prone to creep deformation. Six cases that consider rock Salt with different creep tendency have been conceived for the coupled thermo-mechanical model to investigate the stability of the Salt Cavern in terms of Cavern convergence and failure indices. The results indicate that the affected region by cyclic pressure and temperature is up to 10 m inside the rock Salt from the Cavern wall. It is also revealed from the results that largest displacement occurs on the top of the Cavern, indicating that the Cavern top is most liable to deformation damage. Although convergence of Cavern fluctuates over the injection and withdrawal sessions, long-term convergence of Cavern depends on the creep tendency of rock Salt rather than the cyclic loading; rock Salt with stronger creep tendency leads to larger Cavern convergence. The results also demonstrate that there is stress concentration on the top and bottom of the Cavern; the Cavern wall is likely subject to shear failure according to Mohr‒Coulomb failure criteria, however, the Cavern is unlikely to fail due to expansion according to Drucker‒Prager failure criteria. Both Mohr‒Coulomb and Drucker‒Prager failure indices are smaller in the cases where rock Salt has stronger creep tendency. The proposed thermo-mechanical model provides an approach for evaluation of long-term stability of underground Salt Caverns.
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Physical simulation of flow field and construction process of horizontal Salt Cavern for natural gas storage
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Jie Yang, Xilin Shi, Chunhe Yang, Tongtao Wang, Yue HanAbstract:Abstract Underground Salt Caverns provide appropriate space for storing natural gas. However, Salt Caverns have to be constructed in bedded Salt formations in China. The traditional construction method of Salt Cavern encounters serious problems in such formations. Instead, horizontal Salt Caverns are proposed as a possible alternative for gas storage. Horizontal Caverns can be created by “multi-step retreating” (MSR) method. Two laboratory tests were conducted to understand the shape development and flow field of such Cavern. In one test, we measured fluid velocity distribution in a simulated Salt Cavern environment by particle image velocimetry technology. In another test, the construction process of a Salt Cavern was simulated through MSR method. Results show that the flow field in horizontal Cavern can be divided into five regions. The flow characteristics and rock Salt dissolution properties in these regions are different. A semi-cylindrical Cavern with similar cross section shape along the horizontal direction is obtained through the physical experiment. This study provides important guidance for analyzing the flow field and construction process of the horizontal Salt Cavern.
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thermodynamic response of gas injection and withdrawal process in Salt Cavern for underground gas storage
Applied Thermal Engineering, 2019Co-Authors: Cheng Zhu, Juan Han, Chunhe YangAbstract:Abstract Cycled mode of operation leads to temperature and pressure variation in Salt Cavern for underground gas storage due to mechanical and thermal loading. In this study, based on metamorphic thermodynamic principle, a mathematical model of thermal analysis is proposed for gas injection-and-withdrawal process, formulates a newly analytical solution to temperature and pressure variation with time during injection-and-withdrawal process. The proposed solution is validated with the withdrawal test results. The derived solution can be set as boundary conditions for the thermal-mechanical numerical modeling, which is capable of calculating thermodynamic response for both constant and in-constant air mass flow rate. Fully coupled thermo-mechanical numerical simulations are preformed to evaluate thermal effects on Cavern wall at different gas withdrawal and injection rates. The results indicate that during process of gas-withdrawal, fast withdrawal rate leads to increase of tensile stresses, and there are distinctive tensile stress areas on the roof and floor of the Cavern; while in the gas-injection period, there are no tensile stress area, however, it inclines to occur stress disturbance at intervention of interlayers. Parameters analysis shows that both the thermal coefficients and variation of injection-and-withdrawal rates have impacts on the thermodynamic responses of surrounding rock mass.
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analysis of the plugging process of the leaking interlayer in a thin interbedded Salt Cavern gas storage of jintan china by high pressure grouting and potential applications
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Xiangsheng Chen, Yinping Li, Chunhe Yang, Nan ZhangAbstract:Abstract 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.
Tongtao Wang - One of the best experts on this subject based on the ideXlab platform.
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parameter optimization of solution mining under nitrogen for the construction of a gas storage Salt Cavern
Journal of Natural Gas Science and Engineering, 2021Co-Authors: Jianfu Wang, Tongtao Wang, Jianchao Jia, Wenquan Wang, Baodong Shan, Xiaojin ZhengAbstract:Abstract Using nitrogen as the blanket for the construction of a gas storage Salt Cavern by the solution mining under gas (SMUG) method has many advantages, such as improved safety, enhanced environmental protection and better economy. A critical issue for its field application is how to accurately predict and optimize the Cavern leaching parameters when using SMUG. We propose a mathematical model for predicting leaching parameters based on the “U-tube” principle and the pressure equilibrium of liquid columns in the wellbore. We derive expressions of leaching parameters, including water injection pressure, nitrogen injection pressure, volume of nitrogen blanket, and depth of Gas-Brine (GB) interface. A calculation program is developed based on the derived equations using C# computer language. We take the JT1 Cavern in Jintan district, Jiangsu province, China, as an example, and simulate the water injection pressure, nitrogen injection pressure, volume of nitrogen blanket, and depth of GB interface under different leaching rates and different de-brining pressures. The optimized leaching parameters were used in the leaching of the JT1 Cavern for field tests. Compared with field monitoring data, the proposed mathematical model has high accuracy and strong reliability with an overall error of less than 3.7%, which satisfies the requirements of field Cavern leaching. This study provides guidance for predicting and optimizing leaching parameters for gas storage Salt Cavern leaching with a nitrogen blanket.
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safe distance between debrining tubing inlet and sediment in a gas storage Salt Cavern
Journal of Petroleum Science and Engineering, 2021Co-Authors: Tongtao Wang, Jie Yang, Guoxing Chai, Xueqi Cen, J.j.k. DaemenAbstract:Abstract The proper determination of the distance between the debrining inner tubing (DIT) inlet and sediment during the debrining of an underground gas storage (UGS) Salt Cavern both can increase the expelled brine volume and decrease the risk of blocking the DIT caused either by brine crystallization or by sucking in of large chunks of insoluble solids. Based on the fluid distribution and the force applied to the insoluble particles around the DIT inlet, a mathematical model is built to describe the movement of insoluble particles in a Cavern. The equations are deduced for the forces applied to the particles, the critical fluid rate of the brine, and the critical diameter of particles being sucked in. An equation is given to determine the critical distance between DIT inlet and sediment. Based on the diameter distribution of the insoluble particles, the critical distance is proposed between DIT inlet and sediment under different DIT sizes and debrining rates. Results show that increasing the DIT size can decrease the distance between DIT inlet and sediment greatly, as well as the risk of sucking in insoluble particles. Increasing the diameter of the particles permitted to be sucked in has a slight effect on increasing the debrining volume but notably increases the risk of blocking the DIT. Not permitting insoluble particles being sucked in is proposed as the criterion to determine the distance between the DIT inlet and sediment for an actual debrining. Numerical simulation and field testing results show that the proposed mathematical model has a high accuracy and can effectively guide the field debrining operation.
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Physical simulation of flow field and construction process of horizontal Salt Cavern for natural gas storage
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Jie Yang, Xilin Shi, Chunhe Yang, Tongtao Wang, Yue HanAbstract:Abstract Underground Salt Caverns provide appropriate space for storing natural gas. However, Salt Caverns have to be constructed in bedded Salt formations in China. The traditional construction method of Salt Cavern encounters serious problems in such formations. Instead, horizontal Salt Caverns are proposed as a possible alternative for gas storage. Horizontal Caverns can be created by “multi-step retreating” (MSR) method. Two laboratory tests were conducted to understand the shape development and flow field of such Cavern. In one test, we measured fluid velocity distribution in a simulated Salt Cavern environment by particle image velocimetry technology. In another test, the construction process of a Salt Cavern was simulated through MSR method. Results show that the flow field in horizontal Cavern can be divided into five regions. The flow characteristics and rock Salt dissolution properties in these regions are different. A semi-cylindrical Cavern with similar cross section shape along the horizontal direction is obtained through the physical experiment. This study provides important guidance for analyzing the flow field and construction process of the horizontal Salt Cavern.
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Minimum operating pressure for a gas storage Salt Cavern under an emergency: a case study of Jintan, China
Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, 2020Co-Authors: Tongtao Wang, Jianchao Jia, Wenquan Wang, J J K DaemenAbstract:Decreasing the gas pressure is one of the most effective methods to increase the working gas capacity of Salt Cavern Underground Gas Storages (UGS). In this paper, KING-1 and -2 Caverns of Jintan Salt Cavern UGS, Jiangsu province, China, are studied as an example to investigate their responses under extremely low gas pressure. A 3D geomechanical model of the two Caverns is built based on the geological features and rock properties of the host rock Salt formation. Different operating conditions are simulated. Safety evaluation criteria for completion casing and Caverns are proposed. Thresholds of the indicators consisting of the criteria are given to find the potential minimum gas pressure and the safe working duration of the two Caverns. Calculation results indicate that axial strain (along the vertical direction) can perfectly reflect the effects of low gas pressure on the safety of completion casing. The indicators calculated based on the stresses have advantages compared to those based on deformation in assessing the safety of the Salt Cavern under such low gas pressure and short operating time conditions. The minimum gas pressure gradient of KING-1 and -2 Caverns at the casing shoe can decrease from about 7 kPa/m to 5 kPa/m, viz., the minimum gas pressure can decrease from 7 MPa to 5 MPa. The maximum duration for 5 MPa is no more than 118 days. Taking KING-1 Cavern as an example, the working gas volume can increase about 17.3%. Research results can provide references for Jintan Salt Cavern UGS coping with gas shortages.
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determination of the maximum allowable gas pressure for an underground gas storage Salt Cavern a case study of jintan china
Journal of rock mechanics and geotechnical engineering, 2019Co-Authors: Tongtao Wang, Chunhe Yang, Jianjun Li, Gang Jing, Qingqing Zhang, J J K DaemenAbstract:Abstract Increasing the allowable gas pressure of underground gas storage (UGS) is one of the most effective methods to increase its working gas capacity. In this context, hydraulic fracturing tests are implemented on the target formation for the UGS construction of Jintan Salt Caverns, China, in order to obtain the minimum principal in situ stress and the fracture breakdown pressure. Based on the test results, the maximum allowable gas pressure of the Jintan UGS Salt Cavern is calibrated. To determine the maximum allowable gas pressure, KING-1 and KING-2 Caverns are used as examples. A three-dimensional (3D) geomechanical model is established based on the sonar data of the two Caverns with respect to the features of the target formation. New criteria for evaluating gas penetration failure and gas seepage are proposed. Results show that the maximum allowable gas pressure of the Jintan UGS Salt Cavern can be increased from 17 MPa to 18 MPa (i.e. a gradient of about 18 kPa/m at the casing shoe depth). Based on numerical results, a field test with increasing maximum gas pressure to 18 MPa has been carried out in KING-1 Cavern. Microseismic monitoring has been conducted during the test to evaluate the safety of the rock mass around the Cavern. Field monitoring data show that KING-1 Cavern is safe globally when the maximum gas pressure is increased from 17 MPa to 18 MPa. This shows that the geomechanical model and criteria proposed in this context for evaluating the maximum allowable gas pressure are reliable.
Xilin Shi - One of the best experts on this subject based on the ideXlab platform.
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stability analysis of u shaped horizontal Salt Cavern for underground natural gas storage
Journal of energy storage, 2021Co-Authors: Xilin Shi, Ahu Zhao, Shefeng Hao, Xulong Gong, Su Jiang, Yuan LiuAbstract:Abstract More and more attentions are being paid to horizontal Salt Caverns for natural gas storage because of their large working gas capacity and favorable stability. To accelerate the construction of gas storage underground Salt Caverns, stability analysis of this type of Cavern is necessary to assure the safety of such Caverns. In this paper, the stability is investigated of a U-shaped horizontal Salt Cavern under different constant and cyclic internal gas pressures. A 3D geomechanical model is established based on sonar scanning in the field and predicted Cavern shape. The stability is analyzed of the rock masses around the Cavern under different internal gas pressures and cycle frequencies. Five evaluation criteria are proposed to predict the feasibility and stability of such Caverns, including deformation, dilatancy safety factor, volume shrinkage, plastic zone, and equivalent strain. The stability of the rock mass around the Cavern under different internal gas pressures is compared to that under different cycle frequencies. The results show that the Cavern has a good stability under the constant internal gas pressure of 8 MPa and cyclic internal gas pressures ranging from 8 ~ 18 MPa. The five evaluation indexes of the rock masses around the Cavern improve with increasing internal gas pressure. It is proposed that the corner, horizontal-roof center, and external waist positions of the Cavern are to be highlighted in the design and construction phases. The cycle frequency has appreciable impact on the stability of the rock mass around the Cavern. The difference between the volume shrinkage under cycling compared to constant internal gas pressure is that the cycling simulated results show a rising wave-like curve of creep time. The plastic zone ratio increases with creep time and has a flat peak and a sharp bottom with oscillations. This study provides the design parameters for U-shaped Salt Cavern in the Huaian Salt district and can also be a reference for horizontal Salt Caverns.
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Prediction method for calculating the porosity of insoluble sediments for Salt Cavern gas storage applications
Energy, 2021Co-Authors: Xilin Shi, Kai Zhao, Xin Liu, Chunhe YangAbstract:Abstract Many insoluble sediments accumulate at Cavern bottoms during the construction of Salt Caverns located in highly insoluble Salt formations. Before using the void space for gas storage, knowing the porosity is essential for predicting void volume of insoluble sediments. However, most previous studies have focused on construction and operation of Salt Caverns, and insoluble sediments have been largely ignored. In this study, a series of laboratory tests, including screening and porosity tests, are conducted to obtain the particle size distribution and porosity of samples obtained by dissolving the nonSalt interlayers of target Cavern. The results show that the porosity values of the samples decreases with increasing of fractal dimensions and have no relation to the maximum particle size when the fractal dimension is constant. Based on these results, a porosity prediction method is proposed to calculate the porosity of insoluble sediments combined with fractal and packing theories. In this method, the fractal dimension and the compaction index should be controlled within a reasonable range. The accuracy and reliability of this model was studied by calculating the porosity of insoluble sediments in an actual Salt Cavern. This study can provide a reference for evaluating the void volume in insoluble sediments.
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simulating the transport of brine in the strata of bedded Salt Cavern storage with a fluid solid coupling model
Engineering Geology, 2020Co-Authors: Xiangsheng Chen, Xilin Shi, Tianfu XueAbstract:Abstract The majority of Salt mines in China are located in the strata of lacustrine deposition, which are interbedded structure consisting of rock Salts and non-Salt interlayers. In the solution mining stage, rock Salts will be dissolved to form a cavity for storing natural gas or petroleum. But the non-Salt interlayers will soften or even collapse under the immersion of brine (dissolved rock Salt), some of which will sink to the Cavern bottom to form insolubles, and the other part will become the surrounding rock of this cavity. The retention time of brine in a Salt Cavern depends on the Cavern size and efficiency of solution mining, which is generally about three years. During this period, the brine can seep into the fractures and joints of interlayers, and then inevitably has physical and chemical interactions with the rock minerals (typically montmorillonite). To reveal the affected range and results of brine on the interlayers, this paper takes poro-elasticity theory into account convection–diffusion equation to form a new fluid–solid coupling equation, and then establishes an actual geomechanical simulation model for numerical solution. The calculation results show that the penetration of brine in interlayers is very obvious. The penetration range is 28.37 m within three years, which is about 5.6 times that of rock Salt. As the penetration range increases, the brine pressure gradually decreases and eventually stabilizes. In addition, brine transport has complex coupling boundary conditions composed of concentration, pressure and geostress, which interact with each other. This research contents have important reference and guidance for the study on brine crystallization and halite self-healing, and can lay a foundation for the subsequent safe operation and tightness evaluation of Salt Cavern.
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Physical simulation of flow field and construction process of horizontal Salt Cavern for natural gas storage
Journal of Natural Gas Science and Engineering, 2020Co-Authors: Jie Yang, Xilin Shi, Chunhe Yang, Tongtao Wang, Yue HanAbstract:Abstract Underground Salt Caverns provide appropriate space for storing natural gas. However, Salt Caverns have to be constructed in bedded Salt formations in China. The traditional construction method of Salt Cavern encounters serious problems in such formations. Instead, horizontal Salt Caverns are proposed as a possible alternative for gas storage. Horizontal Caverns can be created by “multi-step retreating” (MSR) method. Two laboratory tests were conducted to understand the shape development and flow field of such Cavern. In one test, we measured fluid velocity distribution in a simulated Salt Cavern environment by particle image velocimetry technology. In another test, the construction process of a Salt Cavern was simulated through MSR method. Results show that the flow field in horizontal Cavern can be divided into five regions. The flow characteristics and rock Salt dissolution properties in these regions are different. A semi-cylindrical Cavern with similar cross section shape along the horizontal direction is obtained through the physical experiment. This study provides important guidance for analyzing the flow field and construction process of the horizontal Salt Cavern.
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experimental device for the study of liquid solid coupled flutter instability of Salt Cavern leaching tubing
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Xilin Shi, Xiangsheng Chen, Chunhe Yang, Chang Shu, Yuanxi LiuAbstract:Abstract A Salt Cavern underground gas storage is typically constructed by water solution mining, in which slender leaching tubings are used as the channel for water injection and brine production. Cavern leaching and well workover operations are accident prone owing to leaching tubings being bended excessively and even ruptured. These accidents are caused primarily by flow-induced vibration of leaching tubings. To investigate these flow-induced vibration phenomena, an in-house laboratory device for liquid–solid coupled flutter instability of Salt Cavern leaching tubing was developed. This experimental device consists primarily of a recirculating flow system, vertical cantilevered pipe test section, and instruments for parameter measurement. The experimental device can be utilized to investigate multiple factors involved in the flow-induced vibration of the leaching tubing, including flexural rigidity, overhang length, and support conditions of tubing string. To verify the adequacy of this device, two sets of experiments have been performed in the air without external space constraints by using a cantilevered silicon rubber and polycarbonate pipes, respectively. Flutter instability phenomena were observed in these experiments. Furthermore, through the study on the length effect, an asymptotic behavior with the critical flow velocity reaching limiting values as the lengths of the pipes increase, is discovered. The present study is conducive to the subsequent experimental step that considers additional factors. Consequently, the device provides adequate in-house experimental conditions for researching the instability mechanism and safety control measures of the leaching tubing.
Yinping Li - One of the best experts on this subject based on the ideXlab platform.
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analysis of the plugging process of the leaking interlayer in a thin interbedded Salt Cavern gas storage of jintan china by high pressure grouting and potential applications
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Xiangsheng Chen, Yinping Li, Chunhe Yang, Nan ZhangAbstract:Abstract 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.
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Experimental device for the study of Liquid–Solid coupled flutter instability of Salt Cavern leaching tubing
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Xinbo Ge, Xiangsheng Chen, Yinping Li, Hongling Ma, Chunhe YangAbstract:Abstract A Salt Cavern underground gas storage is typically constructed by water solution mining, in which slender leaching tubings are used as the channel for water injection and brine production. Cavern leaching and well workover operations are accident prone owing to leaching tubings being bended excessively and even ruptured. These accidents are caused primarily by flow-induced vibration of leaching tubings. To investigate these flow-induced vibration phenomena, an in-house laboratory device for liquid–solid coupled flutter instability of Salt Cavern leaching tubing was developed. This experimental device consists primarily of a recirculating flow system, vertical cantilevered pipe test section, and instruments for parameter measurement. The experimental device can be utilized to investigate multiple factors involved in the flow-induced vibration of the leaching tubing, including flexural rigidity, overhang length, and support conditions of tubing string. To verify the adequacy of this device, two sets of experiments have been performed in the air without external space constraints by using a cantilevered silicon rubber and polycarbonate pipes, respectively. Flutter instability phenomena were observed in these experiments. Furthermore, through the study on the length effect, an asymptotic behavior with the critical flow velocity reaching limiting values as the lengths of the pipes increase, is discovered. The present study is conducive to the subsequent experimental step that considers additional factors. Consequently, the device provides adequate in-house experimental conditions for researching the instability mechanism and safety control measures of the leaching tubing.
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Study on Sealing Failure of Wellbore in Bedded Salt Cavern Gas Storage
Rock Mechanics and Rock Engineering, 2019Co-Authors: Xiangsheng Chen, Xilin Shi, Jianli Ma, Yinping Li, Hongling Ma, Wei Liu, Chunhe YangAbstract:The wellbore tightness of a Salt Cavern gas storage must be tested before solution mining. According to the test results, it will be evaluated whether the wellbore can meet the cementing requirements of gas storage. However, there are many complex reasons that may cause wellbore leakage; hence, how to comprehensively analyze the test results and accurately expose the causes, locations, and scale of the leakage pose many challenges. These mainly include the incomplete test method and lack of theoretical analysis model. A nitrogen leak test was carried out for five wellbores that have been completed in Jintan (Jiangsu, China). The results show that two of them had leakage risk. To clarify the leakage causes and leakage types, we carried out an investigation of engineering geological data of the wellbores and further conducted laboratorial tests and theoretical analysis. The studies of drilling design and engineering geology show that the wellbores have good integrity and initially reveal that a mudstone interlayer intersecting the open hole between the casing shoe and the top of the Salt Cavern is a potential leaking layer. Furthermore, the permeability experiments and CT scans confirm that this mudstone interlayer is a leaking stratum and that the internal cracks develop severely. They are the key reasons leading to wellbore tightness failure. The proposed seepage theoretical model determines that the leakage type is horizontal flow in the mudstone interlayer. Comparing the theoretical results with the field test data, we find that the leakage rate curves of the two are in good agreement, which completely confirms that the mudstone interlayer is the fundamental cause of the wellbores tightness failure. This research not only identifies the leakage causes and leakage types of wellbores, but also enriches the leakage rate analysis method of gas storage and provides a theoretical and experimental analysis method for tightness evaluation of bedded Salt Cavern storage.
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collapse mechanism of the overlying strata above a Salt Cavern by solution mining with double well convection
Environmental Earth Sciences, 2018Co-Authors: Guimin Zhang, Zhenshuo Wang, Yanlong Chen, Yinping Li, Yu Wu, Kai Zhang, Houquan ZhangAbstract:In solution mining of Salt formations, unreasonable Salt cavities formed may lead to surface collapse hazards. In this paper, a mathematical model was proposed to analyze the collapse mechanism of the overlying strata above a Salt Cavern induced by solution mining with double-well convection. In the proposed model, the collapses of the overlying strata were supposed to occur layer by layer, and a thin plate with four edges clamped was introduced to calculate the critical collapse span of each layer. The limit breaking distance of the thin plate can be solved by setting the corresponding surrounding condition. According to the solution, the limit breaking distance is related to the dimensions, the mechanical properties of the rock, the buried depth, and the force status. For the convenience of calculation, a span criterion was introduced to distinguish the limit breaking distance. To keep the immediate roof more stable, the span criterion should be larger. As a case study, the collapse incidents at Dongxing Salt Mine were analyzed by the proposed model, and the collapses were verified to be inevitable under its mining and geological conditions. Discussions were finally carried out to study the influences of the thickness of the immediate roof, tension strength, Poisson ratio, and buried depth on the collapses. Above all, the collapses will occur more easily with the decrease of the thickness, tension strength, and Poisson ratio of each stratum. Especially, the collapse depth will not increase linearly with the buried depth, because of the bulking effect of the overlying strata.
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collapse mechanism of the overlying strata above a Salt Cavern by solution mining with double well convection
Environmental Earth Sciences, 2018Co-Authors: Guimin Zhang, Zhenshuo Wang, Yanlong Chen, Yinping Li, Yu Wu, Kai Zhang, Houquan ZhangAbstract:In solution mining of Salt formations, unreasonable Salt cavities formed may lead to surface collapse hazards. In this paper, a mathematical model was proposed to analyze the collapse mechanism of the overlying strata above a Salt Cavern induced by solution mining with double-well convection. In the proposed model, the collapses of the overlying strata were supposed to occur layer by layer, and a thin plate with four edges clamped was introduced to calculate the critical collapse span of each layer. The limit breaking distance of the thin plate can be solved by setting the corresponding surrounding condition. According to the solution, the limit breaking distance is related to the dimensions, the mechanical properties of the rock, the buried depth, and the force status. For the convenience of calculation, a span criterion was introduced to distinguish the limit breaking distance. To keep the immediate roof more stable, the span criterion should be larger. As a case study, the collapse incidents at Dongxing Salt Mine were analyzed by the proposed model, and the collapses were verified to be inevitable under its mining and geological conditions. Discussions were finally carried out to study the influences of the thickness of the immediate roof, tension strength, Poisson ratio, and buried depth on the collapses. Above all, the collapses will occur more easily with the decrease of the thickness, tension strength, and Poisson ratio of each stratum. Especially, the collapse depth will not increase linearly with the buried depth, because of the bulking effect of the overlying strata.
Xiangsheng Chen - One of the best experts on this subject based on the ideXlab platform.
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tightness and stability evaluation of Salt Cavern underground storage with a new fluid solid coupling seepage model
Journal of Petroleum Science and Engineering, 2021Co-Authors: Xiangsheng Chen, Yufeng Shi, Yalong Jiang, Yuanxi Liu, Jinliang DongAbstract:Abstract The effects of operating pressure and ground stress on the seepage parameters (permeability and porosity) of surrounding rock and stability and tightness of Salt Cavern have been investigated, and a method is proposed for safe operating pressure classification. In previous works, the analysis of stability and tightness of Salt Caverns were mostly carried out independently, and few studies have considered the interaction between them. However, when used as a storage space for natural gas, petroleum and brine, there are many fluid–solid coupling problems in Salt Cavern underground storages. To address these problems, we establish a fluid–solid coupling seepage model based on the relationships between pressure, rock deformation and seepage parameters, and apply it to actual engineering. The coupling analysis results show that the relationship between shrinkage displacement of Salt Cavern and operating pressure is an exponential function with negative correlation, while the relationship between seepage range of a Salt Cavern and the operating pressure is a power function with positive correlation. Therefore, the effects of operating pressure on the stability and tightness of Salt Caverns are diametrically opposite. The seepage range of gas in surrounding formations gradually increases with time, and eventually tends to become stable. Under an operating pressure of 12 MPa and after operating for 30 years, the maximum seepage range and shrinkage displacement of the studied Salt Cavern are 99.72 m and 1.86 m, respectively. Hence the stability and tightness of this Salt Cavern meet the requirements of the regulations in China, and a gas leakage accident will not occur in this storage during operation. The seepage parameters of the surrounding formation increase with operating time of gas storage, and the increase in permeability is larger than that of porosity. The research results can provide reference and guidance for safe operation and parameter design of Salt Cavern underground storage.
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simulating the transport of brine in the strata of bedded Salt Cavern storage with a fluid solid coupling model
Engineering Geology, 2020Co-Authors: Xiangsheng Chen, Xilin Shi, Tianfu XueAbstract:Abstract The majority of Salt mines in China are located in the strata of lacustrine deposition, which are interbedded structure consisting of rock Salts and non-Salt interlayers. In the solution mining stage, rock Salts will be dissolved to form a cavity for storing natural gas or petroleum. But the non-Salt interlayers will soften or even collapse under the immersion of brine (dissolved rock Salt), some of which will sink to the Cavern bottom to form insolubles, and the other part will become the surrounding rock of this cavity. The retention time of brine in a Salt Cavern depends on the Cavern size and efficiency of solution mining, which is generally about three years. During this period, the brine can seep into the fractures and joints of interlayers, and then inevitably has physical and chemical interactions with the rock minerals (typically montmorillonite). To reveal the affected range and results of brine on the interlayers, this paper takes poro-elasticity theory into account convection–diffusion equation to form a new fluid–solid coupling equation, and then establishes an actual geomechanical simulation model for numerical solution. The calculation results show that the penetration of brine in interlayers is very obvious. The penetration range is 28.37 m within three years, which is about 5.6 times that of rock Salt. As the penetration range increases, the brine pressure gradually decreases and eventually stabilizes. In addition, brine transport has complex coupling boundary conditions composed of concentration, pressure and geostress, which interact with each other. This research contents have important reference and guidance for the study on brine crystallization and halite self-healing, and can lay a foundation for the subsequent safe operation and tightness evaluation of Salt Cavern.
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analysis of the plugging process of the leaking interlayer in a thin interbedded Salt Cavern gas storage of jintan china by high pressure grouting and potential applications
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Xiangsheng Chen, Yinping Li, Chunhe Yang, Nan ZhangAbstract:Abstract 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.
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Experimental device for the study of Liquid–Solid coupled flutter instability of Salt Cavern leaching tubing
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Xinbo Ge, Xiangsheng Chen, Yinping Li, Hongling Ma, Chunhe YangAbstract:Abstract A Salt Cavern underground gas storage is typically constructed by water solution mining, in which slender leaching tubings are used as the channel for water injection and brine production. Cavern leaching and well workover operations are accident prone owing to leaching tubings being bended excessively and even ruptured. These accidents are caused primarily by flow-induced vibration of leaching tubings. To investigate these flow-induced vibration phenomena, an in-house laboratory device for liquid–solid coupled flutter instability of Salt Cavern leaching tubing was developed. This experimental device consists primarily of a recirculating flow system, vertical cantilevered pipe test section, and instruments for parameter measurement. The experimental device can be utilized to investigate multiple factors involved in the flow-induced vibration of the leaching tubing, including flexural rigidity, overhang length, and support conditions of tubing string. To verify the adequacy of this device, two sets of experiments have been performed in the air without external space constraints by using a cantilevered silicon rubber and polycarbonate pipes, respectively. Flutter instability phenomena were observed in these experiments. Furthermore, through the study on the length effect, an asymptotic behavior with the critical flow velocity reaching limiting values as the lengths of the pipes increase, is discovered. The present study is conducive to the subsequent experimental step that considers additional factors. Consequently, the device provides adequate in-house experimental conditions for researching the instability mechanism and safety control measures of the leaching tubing.
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experimental device for the study of liquid solid coupled flutter instability of Salt Cavern leaching tubing
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Xilin Shi, Xiangsheng Chen, Chunhe Yang, Chang Shu, Yuanxi LiuAbstract:Abstract A Salt Cavern underground gas storage is typically constructed by water solution mining, in which slender leaching tubings are used as the channel for water injection and brine production. Cavern leaching and well workover operations are accident prone owing to leaching tubings being bended excessively and even ruptured. These accidents are caused primarily by flow-induced vibration of leaching tubings. To investigate these flow-induced vibration phenomena, an in-house laboratory device for liquid–solid coupled flutter instability of Salt Cavern leaching tubing was developed. This experimental device consists primarily of a recirculating flow system, vertical cantilevered pipe test section, and instruments for parameter measurement. The experimental device can be utilized to investigate multiple factors involved in the flow-induced vibration of the leaching tubing, including flexural rigidity, overhang length, and support conditions of tubing string. To verify the adequacy of this device, two sets of experiments have been performed in the air without external space constraints by using a cantilevered silicon rubber and polycarbonate pipes, respectively. Flutter instability phenomena were observed in these experiments. Furthermore, through the study on the length effect, an asymptotic behavior with the critical flow velocity reaching limiting values as the lengths of the pipes increase, is discovered. The present study is conducive to the subsequent experimental step that considers additional factors. Consequently, the device provides adequate in-house experimental conditions for researching the instability mechanism and safety control measures of the leaching tubing.
