A preliminary site selection system for underground hydrogen storage in salt caverns and its application in Pingdingshan,China

Large‐scale underground hydrogen storage(UHS)provides a promising method for increasing the role of hydrogen in the process of carbon neutrality and energy transition.Of all the existing storage deposits,salt caverns are recognized as ideal sites for pure hydrogen storage.Evaluation and optimization of site selection for hydrogen storage facilities in salt caverns have become significant issues.In this article,the software CiteSpace is used to analyze and filter hot topics in published research.Based on a detailed classification and analysis,a“four‐factor”model for the site selection of salt cavern hydrogen storage is proposed,encompassing the dynamic demands of hydrogen energy,geological,hydrological,and ground factors of salt mines.Subsequently,20 basic indicators for comprehensive suitability grading of the target site were screened using the analytic hierarchy process and expert survey methods were adopted,which provided a preliminary site selection system for salt cavern hydrogen storage.Ultimately,the developed system was applied for the evaluation of salt cavern hydrogen storage sites in the salt mines of Pingdingshan City,Henan Province,thereby confirming its rationality and effectiveness.This research provides a feasible method and theoretical basis for the site selection of UHS in salt caverns in China.

Theoretical research on gas seepage in the formations surrounding bedded gas storage salt cavern

When constructing salt cavern gas or petroleum storage in lacustrine sedimentary salt formations rich in mudstone interlayers, the influence of the sealing performance of interlayers and salt-mud interface on the storage tightness should be considered adequately. In order to reveal the gas seepage in deep formations surrounding bedded salt cavern underground storage, a leakage analysis model was established based on the characteristics of a low dip angle and the interbedded structure of bedded rock salt. The gas seepage governing equations for one-dimensional and plane radial flow were derived and solved. A gas seepage simulation experiment was conducted to demonstrate the accuracy and reliability of the theoretical calculation results. The error of the seepage range was approximately 6.70%, which is acceptable. The analysis and calculation results indicate that the motion equation of gas in deep formations satisfies a non-Darcy's law with a threshold pressure gradient and slippage effect. The sufficient condition for the gas flow to stop is that the pressure gradient is equal to the threshold pressure gradient.The relationship between the leakage range and operating time is a positive power function, that is, the leakage range gradually increases with time and eventually stabilizes. As the seepage range increases, the seepage pressure decreases sharply during the early stage, and then decreases gradually until the flow stops.Combining the research results with engineering applications, three quantitative evaluation indexes named the maximum admissible leakage range, leakage volume and leakage rate are proposed for the tightness evaluation of gas storage salt cavern during their operating stage. These indexes can be used directly in actual engineering applications and can be compared with the key design parameters stipulated in the relevant specifications. This work is expected to provide theoretical and technical support for the gas loss and tightness evaluation of gas storage salt caverns.

Experimental salt cavern in offshore ultra-deep water and well designevaluation for CO_(2) abatement

This paper presents a proposal for an experimental salt cavern in offshore ultra-deep water for CO2 abatement,including the instrumentation plan and well conceptual design evaluated for carbon capture and storage(CCS)application.These studies are based on applied computational mechanics associated with field experimentation that has contributed to the technical feasibility of the underground potash mine at the State of Sergipe in Brazil.This knowhow allowed the stability analysis of several salt caverns for brine production at the State of Alagoas in Brazil and to the drilling through stratified thick layers of salt of the pre-salt reservoirs in Santos Basin.Now,this knowledge has been applied in the design of onshore and offshore salt caverns opened by dissolution for storage of natural gas and CO2.The geomechanical study,through the application of computational mechanics,of offshore giant salt caverns of 450 m high by 150 m in diameter,shows that one cavern can store about 4 billion Sm3 or 7.2 million tons of CO2.Before the construction of the giant cavern,which will be the first gas storage offshore in the world,it has been decided to develop an experimental one,with smaller size,to obtained field parameters.The experimental cavern will allow the calibration of parameters to be used in the structural integrity analysis of the cavern and well for storage of natural gas which is rich in CO2 under high pressure.

Determination of the maximum allowable gas pressure for an underground gas storage salt cavern——A case study of Jintan,China

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 k Pa/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.

Dynamic simulation research on injection and withdrawal performance of underground salt cavern natural gas storage

Owing to perfect impermeability,dynamics stability,flexible and efficient operation mode and strong adjustment,underground salt cavern natural gas storage is especially adapted to be used for short-term dispatch.Based on characteristics of gas flow and heat transfer,dynamic mathematic models were built to simulate the injection and withdrawal performance of underground salt cavern gas storage.Temperature and pressure variations of natural gas in gas storage were simulated on the basis of building models during withdrawal operation,and factors affecting on the operation of gas storage were also analyzed.Therefore,these models can provide theore-tic foundation and technology support for the design,building and operation of salt cavern gas storage.

Determination of convergence of underground gas storage caverns using non-invasive methodology based on land surface subsidence measurement

Undergroundgas storage caverns aremonitoredfor environmental safety in termsof equipmentandpotential emissions,particularly methane emissions from the underground and above-ground parts of the storage facility.Periodical measurements of land surface deformations and costly echometric measurements of convergence of individual storage facilities are carried out.The aims of environmental monitoring are:(1)to eliminate potential hazards in the shortest time,(2)assess the overall impact of intensive operation of storage facilities on the environment,(3)developmonitoringmethods relevant to environmental protection,and(4)take actions in case of failure.The paper presents a solution to the problem of determination of the convergence of underground caverns in a salt rock mass based on the results of land surface subsidence measurements carried out using the Gauss-Markov equalization algorithm.Themethod makes it possible for ongoing control of cavern volume convergence after each subsidence measurement on the ground surface and determining the actual impact of the use frequency(injection-mediumconsumption)on the convergence in time.The presentedmethodology is universal and verified on caverns located in a salt rockmass.The Gauss-Markov inversion model is the first used in this area,hence its application is significant.

Dynamic subsidence prediction of ground surface above salt cavern gas storage considering the creep of rock salt

A new model is proposed to predict the dynamic subsidence of ground surface above salt cavern gas storage during the leaching and storage, which takes into account the creep of rock salt. In the model, the extended form of Gaussian curve is adopted to figure out the shape of subsidence areas. The corresponding theoretical formulas are derived. In addition, parameters are studied to investigate the surface subsidence as a function of the salt ejection rate, internal pressure, buried depth, diameter, height, running time, etc. Through an example, the subsidence of the salt cavern gas storage located at Jiangsu of China obtained by the new model was compared with those by Peter A F formula, Schober & Sroka formula and FLAC3D through simulation. The results showed the proposed model is precise and correct, and can meet the actual engineering demands. The surface subsidence is equidirectional with the increase of salt ejection rate, depth, diameter, height, and running time, but reverse to the increase of internal pressure. The depth, diameter, running time and internal pressure have great effects on the subsidence, whereas the salt ejection rate and height have little influences on it.

Stability analysis of the pillars between bedded salt cavern gas storages by cusp catastrophe model

The failure of pillars between bedded salt cavern gas storages can be seen as processes that the deformations of pillars convert from continuous gradual change system to catastrophe state,which are typical nonlinear catastrophe problems.In the paper,the cusp catastrophe model is proposed to obtain the stability factors of pillars.It can overcome the shortages of traditional strength reduction finite element method(SR FEM) and greatly improve the accuracy of stability factors obtained by numerical simulations.The influences of cavern depth,gas pressure,pillar width,and time on the stability factors are studied.Y-1 and Y-2 salt cavern gas storages,located at Jiangsu province of China,were simulated as examples.The stability factors of pillars between Y-1 and Y-2 were evaluated,and the running parameters were recommended to ensure the pillars stability.The results showed that the cusp catastrophe model has high practicability and can precisely predict the stability factors.The stability factors are equidirectional with the increase of gas pressure and pillar width,but reverse to the increase of cavern depth and time.The stability factors of pillars between Y-1 and Y-2 are small for narrow widths,which are influenced greatly by gas pressure,time,pressure difference,and gas production rate.In order to ensure the safety of pillars,the lowest gas pressure,safe running time,max.pressure difference and max.gas production rate of Y-1 and Y-2 were recommended as 7 MPa,5 years,3 MPa,and 0.50 MPa/d,respectively.

新能源用钢管的应用现状、需求分析及思考

“双碳”战略下新能源及相关产业发展给钢管带来新的应用场景,对钢管的功能和性能提出新的需求。聚焦于碳捕获、利用与封存技术领域中的CO_(2)输送用管、氢能领域中的氢气输送用管和储能领域中的盐穴压缩空气储能用注采管,总结了新能源用钢管的应用现状和研究进展,分析了各领域用管需求,并就“双碳”背景下新能源用钢管的基础理论研究、关键技术开发和标准体系建设等方面进行了思考,提出了建议。

中国大规模盐穴储氢需求与挑战

氢能是来源广泛且低碳清洁的能源,大力发展氢能产业是实现双碳目标和应对全球能源转型的重要举措。在氢能“制备―储存―运输―应用”全产业链中,储氢难问题长期制约着氢能产业高质量发展。盐穴储氢具有成本低、规模大、安全性高和储氢纯度高等突出优势,是未来氢能大规模储备的重要发展方向,也是我国能源低碳转型的重大战略需求。综合调研了我国制氢产业和氢能消费现状,分析了我国盐穴储氢的需求。调研了国外利用盐穴储存天然气和氢气的技术及工程现状,总结了我国盐穴储气库发展和建设历程。对比了利用盐穴储存天然气、氦气、压缩空气和氢气的异同点,提出我国盐穴储氢面临三大科技挑战:层状盐岩氢气渗透与生化反应、盐穴储氢库井筒完整性管控、储氢库群灾变孕育与防控。研究成果明确了我国氢气储备需求的快速增长趋势和大规模盐穴储氢的重点攻关方向。

基于U型盐穴储气库的新型CCUS方法

我国江苏、广东等东部地区碳排放量高、碳减排压力大,且缺少适用于大型碳减排的油气藏地质构造,但存在丰富的盐矿资源,以及多年采盐形成大量盐穴老腔。在双碳目标严峻形势下,如何将这些盐腔利用起来实现碳减排具有重要的研究意义。文章基于U型盐穴储气库的特点提出了一种新型CCUS方法,并进行了碳封存量和垫底气替代量计算。结果表明,1对井组可封存二氧化碳8.2万t,天然气垫底气可降低3766×10^(4)m^(3),具有较好的经济效益和社会效益。

基于遗传算法的盐穴储气库注气能力方案优化

盐穴储气库作为中国天然气调峰的重要手段之一,承担着战略储备的重要任务。为提高川气东送输气管网的运行优化能力,对金坛盐穴储气库提出合适的注气配产方案以降低压缩机能耗作为当前阶段的首要目标。通过对金坛盐穴储气库的地理环境、管道参数、储气井参数、压缩机能耗等综合因素进行分析后,以该地区十口井注气流程为例,将其配气方案的能耗分析作为主要目标,在满足于储气库总量、单井注气约束条件的情况下,应用遗传算法对注气任务方案进行优化。通过分析了5组遗传算法进行优化的注气配气过程,结果表明当迭代步数达到25步左右时,总能耗达到收敛且平均每组运行时间为4.57 s,进一步分析得出各单井注气量在优化过程中的趋势图。在符合现场条件、满足于注气需求的情况下,最终模拟优化后的配产方案系相比最初配产方案压缩机能耗下降了33%,实际现场压缩机能耗下降普遍在30%~35%,大幅降低了压缩机能耗浪费,对实际生产应用具有一定的指导作用。

三水盐矿老腔储气库密闭性评价

广东省三水盐矿为低品位盐层,夹层多且岩性变化大,已有盐穴溶腔围岩是否满足储气密闭性值得探究。以三水SS1-4老腔为示范案例,建立了盐穴老腔储气库的密闭性评价数值模拟,研究了所储气体在围岩中的渗透范围、孔隙压力和渗漏量。结合密闭性评价指标,探讨了当夹层不同渗透性时气体在围岩中的渗透特征。该研究为三水盐矿及同类地层老腔储气库的选址和运行等提供了重要指导。

深层盐穴储气库排卤管柱盐结晶实验及现场应用

注气排卤是盐穴储气库建造和安全运行的关键环节。国内在建某深层盐穴储气库埋深大、地层温度高,注气排卤时面临盐结晶堵管风险。为提高排卤效率,同时保证注气排卤顺利进行,文中结合某深层盐穴储气库的地质特征,设计制作了盐穴溶腔注气排卤管柱盐结晶实验装置。通过室内实验,对深层盐穴储气库注气排卤过程中的盐结晶堵管问题进行了深入研究,得到了盐结晶诱导期和排卤管柱内盐结晶规律,并结合深层盐穴储气库注气排卤工程实践,提出现场预防深层排卤管柱盐结晶堵管建议。研究成果为深层盐穴储气库注气排卤现场方案设计和施工提供了理论支撑与实践参考。

超深地层盐岩蠕变试验及储气库长期稳定性研究

为了研究宁晋超深地层盐岩的蠕变特性和长期稳定性,采用岩石伺服三轴流变试验机对盐岩进行三轴蠕变试验分析,分析围压、偏应力、时间对蠕变的影响;通过FLAC3D软件对不同循环内压下运行30 a后腔周塑性区范围、腔周位移进行长期稳定性分析。通过三轴蠕变试验表明:围压的变化能够使蠕变三阶段重新发生;随着偏应力的增大,稳态蠕变率增加;偏应力对蠕变的影响要大于围压对蠕变的影响;宁晋超深储气库石盐矿层蠕变参数为:A=1.55×10-10,n=3.961。长期稳定性模拟研究表明:塑性区位置、最大腔周位移都出现在腔体中部位置;随着流变时间的增加,塑性区范围、腔周位移都逐渐变大;内压越高,塑性区范围、腔周位移越小,运行过程中要避免低压长期运行。

宁晋超深盐穴储气库盐系地层地应力测定分析

地应力是盐穴储气库钻完井设计、运行压力设计等方面的重要基础数据,同时在储气库安全运行、经营管理等方面具有非常重要的意义。宁晋石盐田盐岩平均埋深超过2700 m,而国际上基于超深盐岩地应力的研究鲜有报道,这使宁晋盐穴储气库造腔层段地应力的测定面临很大的技术挑战。文章主要以水压致裂法(HF)和声发射试验(AE)两种测试方法为主,对比已有的区域构造应力测试结果,基于Z1资料井对研究区盐系地层地应力分布特征进行综合分析,研究表明:(1)Z1井盐系地层水平最大主应力方向总体表现为近东西向;(2)Z1井盐系地层地应力整体上随深度增大,水平最大主应力为51.9~60.0 MPa,水平最小主应力为43.2~53.7 MPa,垂向最大应力为65.7 MPa;(3)Z1井盐系地层地应结构总体表现为S_(V)>S_(H)>S_(h),垂向应力为最大主应力,区域应力状态属于正断层应力环境。

盐穴储气库水溶造腔技术概述及优劣势比较

盐穴储气库在中国正处于快速发展阶段,山东、湖北、江苏等盐矿丰富的地区均已开展盐穴储气库建库研究工作。水溶造腔技术是盐穴储气库建库技术的关键技术之一,通过介绍单井对流、单井油(气)垫对流、水平对接井开采、小间距双井单腔等几种常见的水溶造腔技术,系统性分析不同造腔技术的适宜场景以及应用情况,对比其优缺点,以期为后续盐穴储气库水溶造腔技术的选择提供参考。

盐穴储气库井连续油管切割解卡技术实践与应用

连续油管切割技术是利用连续油管的优点研制的新型井下切割工艺,本文通过对连续油管机械切割工艺优化,配套液压锚定器等工具改进,实现了连续油管在盐穴井内成功切割,大幅缩短了施工周期,降低劳动强度,提高施工效率,节约了成本。

Numerical simulation and experimental study on dissolving characteristics of layered salt rocks

Underground salt cavern reservoirs are ideal spaces for energy storage. China is rich in salt rock resources with layered lacustrine sedimentary structures. However, the dissolution mechanism of layered salt rocks remains poorly understood, resulting in significant differences between the actual measurements and the designed indices for the layered salt rock water-soluble cavity-making cycle and the cavity shape. In this work, the dissolution rates of 600 groups of layered salt rocks in China under different conditions were determined experimentally.Thus, the established artificial neural network prediction model was used to assess the effects of the contents of NaCl, Na2 SO4, and CaSO4 in the salt rocks, concentrations, dissolution angles, and flow rates on their dissolution rates by performing ANOVA and F-test. The results provide a theoretical basis for evaluating the dissolution rate of layered salt rocks under different conditions and for the numerical simulation of the layered salt rock water-soluble cavity-making process.

基于小波KPCA-SSA-ELM的盐穴储气库注采管柱内腐蚀速率预测

为提升盐穴储气库注采管柱的内腐蚀速率预测精度,建立了基于小波核主成分分析方法(Kernel Principal Components Analysis, KPCA)和樽海鞘群算法(Salp Swarm Algorithm, SSA)优化的极限学习机(Extreme Learning Machine, ELM)腐蚀速率预测模型。首先通过小波KPCA提取影响注采管柱内腐蚀的主要特征,应用ELM建立盐穴储气库注采管柱内腐蚀速率预测模型,并采用SSA对模型参数进行迭代寻优,避免原参数选取的强随机性对模型泛化能力和预测性能的影响。结果表明,经小波KPCA特征提取后得到包含98.73%原信息的3项主成分,SSA-ELM模型的预测结果与实际值基本吻合,其均方根误差(E_(RMS))为0.009 3,平均绝对百分比误差(E_(MAP))为0.336 0%,决定系数(R~2)高达0.991 2,较其他3种对比模型性能更优。研究表明,所建模型具有强泛化性能和高预测精度,能够有效预测盐穴储气库注采管柱的内腐蚀速率,为盐穴储气库注采系统的完整性评价和风险预警提供参考。