The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Tongtao Wang - One of the best experts on this subject based on the ideXlab platform.

  • Physical simulation of flow field and construction process of horizontal salt Cavern for natural gas storage
    Journal of Natural Gas Science and Engineering, 2020
    Co-Authors: Jie Yang, Tongtao Wang, Chunhe Yang, Xilin Shi, Yue Han
    Abstract:

    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.

  • 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, 2020
    Co-Authors: Tongtao Wang, Jianchao Jia, Wenquan Wang, J J K Daemen
    Abstract:

    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.

  • 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, 2019
    Co-Authors: Tongtao Wang, Chunhe Yang, Jianjun Li, Gang Jing, Qingqing Zhang, J J K Daemen
    Abstract:

    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.

  • Determination of the maximum allowable gas pressure for an underground gas storage salt Cavern – A case study of Jintan, China
    Elsevier, 2019
    Co-Authors: Tongtao Wang, Chunhe Yang, Gang Jing, Qingqing Zhang, J J K Daemen
    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. Keywords: Underground gas storage (UGS) salt Cavern, In situ stress testing, Maximum gas pressure, Gas penetration failure, Microseismic monitorin

  • salt Cavern gas storage in an ultra deep formation in hubei china
    International Journal of Rock Mechanics and Mining Sciences, 2018
    Co-Authors: Tongtao Wang, Chunhe Yang, Jianjun Li, N Zhang, S L Ding
    Abstract:

    Abstract The target formation of Jianghan salt district, Qianjiang city, Hubei province, China, for underground gas storage (UGS) construction has a depth of more than 1800 m. The Cavern will be the deepest salt Cavern UGS in Asia. A 3D geomechanical model of the proposed salt Cavern UGS is built based on the geologic characteristics and mechanical parameters of the target formation. A new indexes system composed of displacement, volume shrinkage, plastic zone, dilatancy safety factor, and equivalent strain is proposed to quantitatively evaluate the safety of Jianghan salt Cavern UGS. The thresholds of each indicator are proposed based on the characteristics of rock salt in China. By using the proposed indexes system, the Cavern shape, dimensions, operating parameters and pillar width are optimized. Calculating results show that the optimized Cavern has a slender cylindrical shape with a domed roof and an inverted cone bottom; its diameter ranges from 80 to 90 m, its height is about 210 m, and its free volume (accessible to gas) is about 50–65×104 m3. The maximum operating gas pressure is about 34 MPa, and the minimum gas pressure is no less than 17 MPa. The width of the pillar between adjacent Caverns is about 2.5–3 times the Cavern diameter. The gas storage capacity of a single Cavern is about 1.1×109 m3, and the working gas is about 0.7×109 m3, which is about three times that of a single Cavern in Jintan salt Cavern UGS, Jiangsu province, China. The results indicate that Jianghan salt Cavern UGS has a good feasibility for large-scale gas storage.

Chunhe Yang - One of the best experts on this subject based on the ideXlab platform.

  • investigation of thermal mechanical effects on salt Cavern during cycling loading
    Energy, 2021
    Co-Authors: Xing Nan, Jiasong Chen, Chunhe Yang
    Abstract:

    Abstract Traditional stability analysis for salt Cavern as UGS overlooks the thermal effects induced by cycling loading and cannot predict the potential risk. In this study viscoelastic WIPP model is employed to describe the temperature-dependent creep behavior of rock salt. A thermal-mechanical simulation framework is established to couple the effect of mechanical stress and thermal stress. A coupling thermal-mechanical numerical model implemented by FLAC3D in combination with the WIPP creep model is proposed. A field case, Cavern L, in Jintan, Jiangsu Province of China is demonstrated in this paper to explore the thermal response to gas injection-and-withdrawal process. The results show that there is tensile stress concentration region at the Cavern roof. The dynamic process of thermal damage evolution and block falls on Cavern roof is also investigated. The disintegration of rock salt mass at Cavern roof occurs after the most severe gas depressurization period, and the retain of low pressure after gas withdrawal aggravate the thermal damage. It indicates that the thermal-induced tensile stresses are critical for salt Cavern stability assessment. The feasibility and accuracy of the proposed thermal-mechanical modeling is verified by the field case, and the simulation results of thermal damage are coincided with the sonar results. This analysis confirmed the influence of thermal-mechanical effects on salt Cavern wall. The approach used in this study provides an improved method for the stability evaluation and optimal operation parameters for salt Caverns.

  • Prediction method for calculating the porosity of insoluble sediments for salt Cavern gas storage applications
    Energy, 2021
    Co-Authors: Xilin Shi, Kai Zhao, Xin Liu, Chunhe Yang
    Abstract:

    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.

  • failure analysis for gas storage salt Cavern by thermo mechanical modelling considering rock salt creep
    Journal of energy storage, 2020
    Co-Authors: Xiuxiu Miao, Chunhe Yang
    Abstract:

    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.

  • Physical simulation of flow field and construction process of horizontal salt Cavern for natural gas storage
    Journal of Natural Gas Science and Engineering, 2020
    Co-Authors: Jie Yang, Tongtao Wang, Chunhe Yang, Xilin Shi, Yue Han
    Abstract:

    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.

  • 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, 2019
    Co-Authors: Tongtao Wang, Chunhe Yang, Jianjun Li, Gang Jing, Qingqing Zhang, J J K Daemen
    Abstract:

    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.

J J K Daemen - One of the best experts on this subject based on the ideXlab platform.

  • 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, 2020
    Co-Authors: Tongtao Wang, Jianchao Jia, Wenquan Wang, J J K Daemen
    Abstract:

    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.

  • 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, 2019
    Co-Authors: Tongtao Wang, Chunhe Yang, Jianjun Li, Gang Jing, Qingqing Zhang, J J K Daemen
    Abstract:

    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.

  • Determination of the maximum allowable gas pressure for an underground gas storage salt Cavern – A case study of Jintan, China
    Elsevier, 2019
    Co-Authors: Tongtao Wang, Chunhe Yang, Gang Jing, Qingqing Zhang, J J K Daemen
    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. Keywords: Underground gas storage (UGS) salt Cavern, In situ stress testing, Maximum gas pressure, Gas penetration failure, Microseismic monitorin

  • stability and availability evaluation of underground strategic petroleum reserve spr Caverns in bedded rock salt of jintan china
    Energy, 2017
    Co-Authors: Nan Zhang, Tongtao Wang, Chunhe Yang, Xilin Shi, Wei Liu, J J K Daemen
    Abstract:

    Abstract Due to the rock salt resources in China mainly being bedded salt, it brings great challenges for the strategic petroleum reserve (SPR) Cavern construction and safety evaluation. A series of investigations are presented to analyze the stability and availability of the China's first underground SPR salt Cavern facilities, located in bedded rock of Jintan, China. Systematic mechanics experiments of rocks surrounding SPR Cavern were carried out to determine their properties. A 3D-geomechanical model is developed based on the mechanical test results and the characteristics of the target formation. Results show that the bedded rock salts in Jintan salt mine are suitable to construct underground SPR facilities. The interlayers in the bedded rock salt are beneficial to the stability of the underground SPR salt Caverns because of their ‘Reinforcement Effect’. The results also demonstrate that a number of existing abandoned salt Caverns in Jintan salt mine which are unsuitable for gas storage can be rebuilt for SPR in the future. The results can also provide a reference for the implementation of similar projects in other places.

  • feasibility analysis of using closely spaced Caverns in bedded rock salt for underground gas storage a case study
    Environmental Earth Sciences, 2016
    Co-Authors: Chunhe Yang, Tongtao Wang, Jianjun Li, J J K Daemen
    Abstract:

    A closely spaced Caverns design for large-scale underground gas storage (UGS) is proposed, in which four Caverns compose one group. The pillar widths between adjacent Caverns are 0.7D in the same group and 1.5D between different adjacent groups (D is the maximum diameter of the Cavern). Caverns in the same group operate with the same injection–production mode to decrease the negative effects of running parameters on the pillar safety. Thicknesses of salt between the Cavern and the upper and lower mudstone layers are about 15 m. To verify the design, a three-dimensional geomechanical numerical model is built by ANSYS software, taking into account Jintan salt mine strata characteristics, mechanical behavior properties and running of the UGS, to monitor the deformations and stresses of the model. The deformations, volume shrinkages, plastic zone extension and configuration, equivalent strain, and safety factor are studied with the three-dimensional geomechanical numerical model. The results obtained by the numerical simulations and the model experiments show that the three-dimensional geomechanical numerical model has a high accuracy, the safety of the closely spaced Caverns UGS can be ensured under different running conditions, and the proposed design has a good feasibility. This design can double the number of Caverns of the original design and provide additional storage capacity of about 10 × 104 m3 for a single Cavern. This approach can be implemented for similar projects in other places.

Wei Liu - One of the best experts on this subject based on the ideXlab platform.

  • stability analysis of a typical two well horizontal saddle shaped salt Cavern
    Journal of energy storage, 2021
    Co-Authors: Guangjie Yuan, Wei Liu, Jifang Wan, Tianji Peng, Maria Jose Jurado, Fansheng Ban, Yan Xia, Hong Zhang
    Abstract:

    Abstract 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.

  • research on gas leakage and collapse in the Cavern roof of underground natural gas storage in thinly bedded salt rocks
    Journal of energy storage, 2020
    Co-Authors: Wei Liu, Deyi Jiang, Zhixin Zhang, Jinyang Fan, Jie Chen
    Abstract:

    Abstract 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.

  • evaluation of potential for salt Cavern gas storage and integration of brine extraction Cavern utilization yangtze river delta region
    Natural resources research, 2020
    Co-Authors: Wei Liu, Xiong Zhang, Jinyan Fan, Lu Wang
    Abstract:

    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.

  • physical simulation of construction and control of two butted well horizontal Cavern energy storage using large molded rock salt specimens
    Energy, 2019
    Co-Authors: Wei Liu, Deyi Jiang, Jie Chen, Zhixin Zhang, Jinyang Fan, Daemen Jjk
    Abstract:

    Abstract 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.

  • study on the mechanism of roof collapse and leakage of horizontal Cavern in thinly bedded salt rocks
    Environmental Earth Sciences, 2019
    Co-Authors: Zhixin Zhang, Deyi Jiang, Jie Chen, Wei Liu, Jinyang Fan, Kainan Xie
    Abstract:

    In the thinly bedded salt formations, due to the limited thickness of the salt strata along with the fast upward dissolution, the collapse of the non-salt roof of the Cavern often occurs, leading to the leakage of brine and instability of the Cavern as well as other undesirable geological consequences. To investigate the gypsum-salt interbedded roof collapse, the failure mechanism and the control methods of Dainan siltstone, which is the indirect roof of the horizontal salt Caverns in Zhaoji Salt Mine, were thoroughly investigated. Through the drilled cores from this mine, a series of contrast tests such as SEM, EDS, XRD, soaking, and nuclear magnetic properties were carried out to study the physical properties of the salt layer and non-salt layer of the Cavern roof and to determine the Cavern roof collapse and leakage mechanism. Using the Comsol software, the model of a horizontal Cavern roof leakage was established, and the leakage range and leakage of brine at different time were analyzed, as well as the safety problems caused by it. Finally, some suggestions have been provided for the leakage control of the Cavern roof in bedded salt Cavern.

Xilin Shi - One of the best experts on this subject based on the ideXlab platform.

  • stability analysis of u shaped horizontal salt Cavern for underground natural gas storage
    Journal of energy storage, 2021
    Co-Authors: Xilin Shi, Ahu Zhao, Shefeng Hao, Xulong Gong, Su Jiang, Yuan Liu
    Abstract:

    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.

  • Prediction method for calculating the porosity of insoluble sediments for salt Cavern gas storage applications
    Energy, 2021
    Co-Authors: Xilin Shi, Kai Zhao, Xin Liu, Chunhe Yang
    Abstract:

    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.

  • Physical simulation of flow field and construction process of horizontal salt Cavern for natural gas storage
    Journal of Natural Gas Science and Engineering, 2020
    Co-Authors: Jie Yang, Tongtao Wang, Chunhe Yang, Xilin Shi, Yue Han
    Abstract:

    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.

  • Mathematic modelling of the debrining for a salt Cavern gas storage
    Journal of Natural Gas Science and Engineering, 2018
    Co-Authors: Tongtao Wang, Chunhe Yang, Wang Huimeng, Shuanglong Ding, Xilin Shi
    Abstract:

    Abstract Debrining is one of the key steps to complete the construction of a salt Cavern gas storage, which determines whether the Cavern can transfer to underground gas storage (UGS) and the effective volume of a salt Cavern UGS. A mathematical model is proposed based on the change characteristic of the dynamic depth of the interface between gas and brine and the pressure equilibrium principle to predict the parameters of the debrining. The calculating equations of debrining parameters, such as, total debrining time, gas injection pressure, gas injection volume per day, and cumulative gas injection volume, are deduced. A calculating program is developed based on the deduced equations by using Visual Basic computer language. To verify the proposed mathematical model, MZ-1 Cavern of Jintan salt district, Jiangsu province, China, is simulated as an example. Based on the calculating results, the debrining parameters of MZ-1 Cavern are optimized. These parameters were used in the debrining of MZ-1 Cavern. By comparing the analytical results with field monitoring data, the proposed mathematical model is shown to have a high accuracy. The error between the predicting results and the field monitoring data is less than 5%, which can satisfy the requirement of actual debrining prediction. Research results can provide the parameter optimization and prediction for the debrining of salt Caverns used for gas storage in Jintan salt district and some other places with similar conditions.

  • stability and availability evaluation of underground strategic petroleum reserve spr Caverns in bedded rock salt of jintan china
    Energy, 2017
    Co-Authors: Nan Zhang, Tongtao Wang, Chunhe Yang, Xilin Shi, Wei Liu, J J K Daemen
    Abstract:

    Abstract Due to the rock salt resources in China mainly being bedded salt, it brings great challenges for the strategic petroleum reserve (SPR) Cavern construction and safety evaluation. A series of investigations are presented to analyze the stability and availability of the China's first underground SPR salt Cavern facilities, located in bedded rock of Jintan, China. Systematic mechanics experiments of rocks surrounding SPR Cavern were carried out to determine their properties. A 3D-geomechanical model is developed based on the mechanical test results and the characteristics of the target formation. Results show that the bedded rock salts in Jintan salt mine are suitable to construct underground SPR facilities. The interlayers in the bedded rock salt are beneficial to the stability of the underground SPR salt Caverns because of their ‘Reinforcement Effect’. The results also demonstrate that a number of existing abandoned salt Caverns in Jintan salt mine which are unsuitable for gas storage can be rebuilt for SPR in the future. The results can also provide a reference for the implementation of similar projects in other places.