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.

Diffusion-controlled Adsorption Kinetics at Air/Solution Surface Studied by Maximum Bubble Pressure Method

In studying the diffusion-controlled adsorption kinetics of aqueous surfactant solutions at the air/solution surface by means of the maximal bubble pressure method, Fick's diffusion equation for a sphere should be used. In this paper the equation was solved by means of Laplace transformation under different initial and boundary conditions. The dynamic surface adsorption F(t) for a surfactant solution, which was used to describe the diffusion-controlled adsorption kinetics at the solution surface, was derived. Different from the planar surface adsorption, the dynamic surface adsorption F(t) for the short time consists of two terms: one is the same as Ward-Tordai equation and the other reflects the geometric effect caused by the spherical bubble surface. This effect should not be neglected for the very small radius of the capillary. The equilibrium surface tension γeq and the dynamic surface tension γ(t) of aqueous C10E6 [CH3(CH2)9(OCH2CH2)6OH] solution at temperature 25℃ were measuredby means of Wilhelmy plate method and maximal bubble pressure method respectively. As t→ 0, the theoreticalanalysis is in good agreement with experimental results and the dependence of γ(t) on is linear.

A formation pressure prediction method based on tectonic overpressure

Traditional formation pressure prediction methods all are based on the formation undercompaction mechanism and the prediction results are obviously low when predicting abnormally high pressure caused by compressional structure overpressure.To eliminate this problem,we propose a new formation pressure prediction method considering compressional structure overpressure as the dominant factor causing abnormally high pressure.First,we establish a model for predicting maximum principal stress,this virtual maximum principal stress is calculated by a double stress field analysis.Then we predict the formation pressure by fitting the maximum principal stress with formation pressure. The real maximum principal stress can be determined by caculating the sum of the virtual maximum principal stresses.Practical application to real data from the A1 and A2 wells in the A gas field shows that this new method has higher accuracy than the traditional equivalent depth method.

Investigation on short-term burst pressure of plastic pipes reinforced by cross helically wound steel wires

Plastic pipes reinforced by cross helically wound steel wires (PSP), which have exhibited excellent mechanical performance, consist of inner polyethylene (PE) layer, winding layer and outer PE layer. The winding layer is composed of two monolayers where steel wires are cross helically wound. An analytical procedure is developed to predict the short-term burst pressure of PSP as the monolayer is assumed to be elastic and orthotropic. The 3D anisotropic elasticity and Maximum Stress Failure Criterion are employed in the formulation of the elasticity problem. Good agreement between the theoretical results and the experimental data shows that the proposed approach can well predict the short-term burst pressure of PSP.

Urethral pressure profilometry in artificial urinary sphincter implantation: A case report

BACKGROUND Artificial urethral sphincter(AUS)implantation is currently the gold standard for treating moderate and severe urinary incontinence.Currently,cuffs are chosen based on the surgeon’s experience,and adjusting cuff tightness is crucial.The TDOC air-charged catheter has not been proven to be inferior to traditional catheters.We report how intraoperative urethral pressure profilometry is performed using a T-DOC air-charged catheter with ambulatory urodynamic equipment,to guide cuff selection and adjustment.CASE SUMMARY A 67-year-old man presented to our hospital with complete urinary incontinence following transurethral prostatectomy,using five pads/d to maintain local dryness.Preoperatively,the maximum urethral pressure(MUP)and maximum urethral closure pressure(MUCP)were 52 cmH2O and 17 cmH2O,respectively.An AUS was implanted.Intraoperatively,in the inactivated state,the MUP and MUCP were 53 cmH2O and 50 cmH2O,respectively;in the activated state,they were 112 cmH2O and 109 cmH2O,respectively.The pump was activated 6 wk postoperatively.Re-measurement of the urethral pressure on the same day showed that in the inactivated state,MUP and MUCP were 89 cmH2O and 51 cmH2O,respectively,and in the activated state,120 cmH2O and 92 cmH2O,respectively.One month after device activation,telephonic follow-up revealed that pad use had decreased from five pads/d to one pad/d,which met the standard for social continence(0-1 pad per day).There were no complications.CONCLUSION The relationship between intraoperative urethral pressure and urinary continence post-surgery can provide data for standardizing AUS implantation and evaluating efficacy.

Probability Analysis of the Wave-Slamming Pressure Values of the Horizontal Deck with Elastic Support

This paper presents the probability distribution of the slamming pressure from an experimental study of regular wave slamming on an elastically supported horizontal deck. The time series of the slamming pressure during the wave impact were first obtained through statistical analyses on experimental data. The exceeding probability distribution of the maximum slamming pressure peak and distribution parameters were analyzed, and the results show that the exceeding probability distribution of the maximum slamming pressure peak accords with the three-parameter Weibull distribution. Furthermore, the range and relationships of the distribution parameters were studied. The sum of the location parameter D and the scale parameter L was approximately equal to 1.0, and the exceeding probability was more than 36.79% when the random peak was equal to the sample average during the wave impact. The variation of the distribution parameters and slamming pressure under different model conditions were comprehensively presented, and the parameter values of the Weibull distribution of wave-slamming pressure peaks were different due to different test models. The parameter values were found to decrease due to the increased stiffness of the elastic support. The damage criterion of the structure model caused by the wave impact was initially discussed, and the structure model was destroyed when the average slamming time was greater than a certain value during the duration of the wave impact. The conclusions of the experimental study were then described.

Aerodynamic Optimization of the Expansion Section in a Hypersonic Quiet Nozzle Based on Favorable Pressure Effect

Maximum expansion angle is the primary parameter for the design of expansion section of hypersonic quiet nozzle. According to the quantity of maximum expansion angle, expansion section could be classified as fast expansion and slow expansion. In order to diminish the effect of instability of Görtler vortex, gradually, slow expansion was employed for quiet nozzle design. Based on the favorable pressure effect, the maximum expansion angle is optimized in this paper, and a considerable selective session of maximum expansion angle is obtained. The trend that slow expansion is employed instead of fast expansion is explained, and a new method is established for aerodynamic optimization of expansion section contour in a quiet nozzle.

Visualizing Relationships between Drivers of Environmental Change and Pressures on Land-Based Ecosystems

The pursuit of human needs and demands is placing more pressure on land resources than ever before. The challenge of feeding 7 billion people is increasingly competing with rising demands for materials and biofuels. Deforestation and land degradation are among the pressing outcomes of these trends. Drivers of environmental change—including population growth, economic activity, consumption, urbanization, trade, conflict, and governance—clearly play a role in aggravating or mitigating these pressures on land. Despite advances in understanding causality in complex systems, navigating the interactions between these drivers remains a major challenge. This paper analyzes and visualizes the relationships between multiple, interacting drivers of environmental change and specific pressures on land-based ecosystems. Drawing on experience from the development of the Drivers and Land chapters of the UN Environment Programme’s Fifth Global Environment Outlook report (GEO-5), we use a series of Kiviat diagrams to illustrate the relative influence of key drivers on selected pressures on land. When individual diagrams are overlaid, patterns of influence emerge that can provide insight into where policy responses might best be targeted. We propose that, subject to some limitations, the Kiviat exercise can provide an accessible and potentially valuable “knowledge-intermediary” tool to help link science-based information to policy action.

Trump Administration's North Korea Policy Logic and DPRK Nuclear Issue Prospects

The North Korea nuclear challenge,urgent on the US foreign policy agenda since Donald Trump took office,has prompted unilateral,bilateral and multilateral moves to address rising tension on the peninsula.The underlying logic of US policy,which in November placed the DPRK back on the list of state sponsors of terrorism,promotes negotiation by imposing Maximum Pressure and by enlisting China's support.Possibly,North Korea will return to negotiations with its nuclear and missile development suspended temporarily.Other possibilities are a stalemate with North Korea joining the ranks of countries with credible nuclear deterrent,or an emerging crisis that escalates to military or other conflict.The lingering uncertainty is central to northeast Asia security.

The Diffusion of Bilateral Tendencies in the Common Trade Policy of the European Union During the Global Financial and Economic Crisis

In this research work, the author focuses on the analysis of the diffusion of bilateral tendencies in the common trade policy of the European Union （EU） during the global financial and economic crisis. Realistic point is important trends in the trade regime during the economic crisis. The decisions taken by the representatives of the governments participating in the World Trade Organisation （WTO） are, to a significant degree, influenced by various lobbies, such as organisations and unions of food producers or other non-governmental organisations, including trade unions, The main objective of the research task is to give a comprehensive analysis of the international trade policy during the world financial and economic crisis 2008-2010. The particular mains concern the political economy models of foreign trade policy, protectionistic pressures in different political system, the level of protectionistic pressures, food producer pressures, international trade liberalization, and environmental protection bilateral tendencies in the common trade policy of the EU and the respond of the EU to the economic crisis, it must be emphasized that on a theoretical level, understanding the choice of trade policies between liberalizm and protectionisme is very important. Despite the undeniable benefits of the multilateral WTO forum for trade liberalisation, the rapid increase of North-South bilateral and multilateral Free Trade Areas （FTAs） begs a systematic explanation for why some forums are prioritized relative to others.

面向波动可再生能源的质子交换膜电制氢系统最优压强运行

为提升质子交换膜电制氢系统在波动可再生能源输入下的制氢效率,提出面向最大效率的质子交换膜电制氢系统最优压强运行模式。介绍质子交换膜电制氢系统,提出基于压强控制的协调运行原理;对质子交换膜电制氢系统的压强特性和功率特性进行建模,从而建立面向最大效率的压强优化模型。在波动电流输入算例下检验最优压强运行模式的制氢效果,结果表明,相较于恒定压强模式,最优压强运行模式下的质子交换膜电制氢系统平均制氢能耗得到有效降低,系统性能得到明显提升。

长江漫滩相超固结软土最大动剪切模量试验研究

为探究长江漫滩相超固结软土最大动剪切模量G_(max)变化特征,利用弯曲元对原状长江漫滩相软土开展了系列试验研究,探讨了不同超固结比H_(OCR)、初始有效固结围压σ'_(3c)及孔隙比e对漫滩相软土G_(max)的影响规律。试验结果表明,当σ'_(3c)和H_(OCR)均相同时,G_(max)随e的增大而减小;H_(OCR)的增大会导致G_(max)随e的衰减速度逐渐降低,而σ'_(3c)的增大不会引起G_(max)衰减速度的变化。孔隙归准化最大剪切模量G_(max)/F(e)随归准化初始有效围压σ'_(c0)/Pa的增大而增加,但其增长速率逐渐降低,G_(max)/F(e)与σ'_(3c)/Pa呈幂函数关系。基于回归分析,提出了合理表征具有不同超固结状态、初始应力条件及密实程度的长江漫滩相软土G_(max)预测方法,并通过独立试验验证了该方法的有效性。

最大气泡压力法测定溶液表面张力实验的优化设计

从测试溶液类型、实验数据的处理方法两方面对最大气泡压力法测定表面张力实验做出改进。改进后的实验将促使学生更深入地全面掌握溶液表面的性质如吸附现象、吸附量和表面活性剂的临界胶束浓度等,学生能够从本实验中获得知识最大化,拓展学生实验思路。此外,采用origin软件处理实验数据,有助于提高学生处理实验数据的能力,提高学生实验综合能力。

Sealing capacity evaluation of underground gas storage under intricate geological conditions

Evaluating underground gas storage(UGS)sealing capacity is essential for its safe construction and operational efficiency.This involves evaluating both the static sealing capacity of traps during hydrocarbon accumulation and the dynamic sealing capacity of UGS under intensive gas injection and withdrawal,and alternating loads.This study detailed the methodology developed by Sinopec.The approach merges disciplines like geology,geomechanics,and hydrodynamics,employing both dynamic-static and qualitative-quantitative analyses.Sinopec's evaluation methods,grounded in the in situ stress analysis,include mechanistic studies,laboratory tests,geological surveys,stress analysis,and fluid-solid interactions.Through tests on the static and dynamic sealing capacity of UGS,alongside investigations into sealing mechanisms and the geological and geomechanical properties of cap rocks and faults,A geomechanics-rock damage-seepage mechanics dynamic coupling analysis method has been developed to predict in situ stress variations relative to pore pressure changes during UGS operations and evaluate fault sealing capacity and cap rock integrity,thereby setting the maximum operational pressures.Utilizing this evaluation technique,Sinopec has defined performance metrics and criteria for evaluating the sealing capacity of depleted gas reservoirs,enabling preliminary sealing capacity evaluations at UGS sites.These evaluations have significantly informed the design of UGS construction schemes and the evaluation of fault sealing capacity and cap rock integrity during UGS operations.

页岩油藏逆向渗吸的最大渗吸动用距离计算方法

渗吸是页岩油藏压裂开发的重要机理,最大渗吸动用距离是渗吸动用范围评价的直接指标,对页岩油藏开发具有重要意义。为确定页岩油藏最大渗吸动用距离,在表征页岩油藏毛细管力曲线基础上,运用渗流理论、数值计算方法,建立了页岩油藏逆向渗吸最大渗吸动用距离计算方法,通过与室内实验结果进行对比,验证了计算方法的可靠性,同时开展了最大渗吸动用距离影响因素分析。研究表明:随着渗透率增加,最大渗吸动用距离呈线性增加,但达到最大渗吸动用距离所用时间呈指数降低;油水黏度比对最大渗吸动用距离无影响,但原油黏度越大,达到最大渗吸动用距离所需时间越长;当储层渗透率为0.05 mD、接触角为45°、界面张力为50 mN/m时,最大渗吸动用距离为2.2 m,所需时间为170 d,用时较长。该研究可为页岩油藏渗吸动用范围评价提供借鉴。

气顶砂岩油藏型储气库运行上限压力和库容量定量评价研究

提高运行上限压力是增加储气库工作气量最直接、最有效且综合效益最优的方案。通过在矿场井中原位实测得到的最小主应力,对冀东南堡油田1-29气顶砂岩油藏型储气库的运行上限压力和库容量进行了定量评价,研究结果表明:基于最小主应力准则,盖层发生拉张破坏对应的上限压力最低,即根据实测最小主应力确定南堡油田1-29储气库的运行上限压力为27.2 MPa。基于有效库容计算模型,综合考虑气层含水量、残余水和边缘孔隙以及油层的波及系数、气驱液效率和含油空间利用率等因素,将上限压力从原始地层压力22.5 MPa提升到27.2 MPa,储气库的有效库容从15.46×10^(8)m^(3)增加到18.14×10^(8)m^(3),库容量增加约17.3%,预期可显著提升储气库的经济效益。研究成果对其他地下储气库运行上限压力和库容量定量评价具有一定参考价值。

基于最大净功率输出的PEMFC阴极供气系统优化控制研究

通过建立质子交换膜燃料电池(PEMFC)阴极供气系统数学模型,分析空气压缩机电压和背压阀开度对系统净功率输出的影响;针对负载电流变化,研究PEMFC系统对应的最优过氧比和最优阴极压力,建立最大输出净功率-过氧比-阴极压力寻优表;考虑过氧比和阴极压力之间的耦合关系,基于辨识出的传递函数矩阵,设计针对空气压缩机电压和背压阀开度的前馈解耦控制器,优化氧气供给和压力控制,并进行相应的仿真验证。结果表明,所提解耦控制器能有效减小过氧比和阴极压力之间的耦合影响,在实现最大净功率闭环控制的同时,具有更快的响应速度和更小的超调量。

青年人躯干压力生物反馈与膈肌功能参数的相关性

背景:躯干压力生物反馈被认为是评估核心肌肉力量的一个可靠指标,其不仅能反映个体躯干力量状况,而且与呼吸肌功能有着密切关系。目的:探讨青年人躯干压力生物反馈与膈肌功能之间的相关性。方法:选择上饶师范学院80名大学生为研究对象,男34名,女46名,年龄(19.83±1.45)岁,采用床旁肌骨超声系统测量受试者膈肌厚度和移动度,便携式肺功能检测仪检测受试者最大吸气压,压力生物反馈仪测试受试者俯卧与仰卧位的腰部及腹部压力。采用Pearson或Spearman相关系数确定躯干压力生物反馈与膈肌功能之间的相关程度,多元线性回归分析确定膈肌功能的预测模型。结果与结论:①以性别分组,男子组年龄、身高、体质量、躯干压力生物反馈数值、平静吸气末膈肌厚度、平静呼气末膈肌厚度、平静呼吸膈肌增厚率、深吸气末膈肌厚度、深呼气末膈肌厚度、深吸气膈肌移动度、最大吸气压均大于女子组(P均<0.05);②以体力活动水平分组,久坐组躯干压力生物反馈数值及最大吸气压均低于运动组(P均<0.05);③相关性分析显示,躯干压力生物反馈(俯卧)、躯干压力生物反馈(仰卧)与平静吸气末膈肌厚度、平静呼气末膈肌厚度、平静呼吸膈肌增厚率、深吸气末膈肌厚度、深呼气末膈肌厚度、深呼吸膈肌增厚率、深吸气膈肌移动度、最大吸气压均具有显著性相关关系(P均<0.01);④多元线性回归分析显示,躯干压力生物反馈(俯卧)进入平静吸气末膈肌厚度的预测模型(F=27.228,P<0.001),躯干压力生物反馈(俯卧)进入深吸气末膈肌厚度的预测模型(F=38.615,P<0.001),躯干压力生物反馈(仰卧)、年龄进入深吸气膈肌移动度的预测模型(F=15.408,P<0.001),躯干压力生物反馈(俯卧)、体质量、年龄进入最大吸气压的预测模型(F=22.314,P<0.001);⑤结果显示,躯干压力生物反馈与膈肌厚度、膈肌移动度和最大吸气压的相关性较强,快速简便的躯干压力生物反馈测量可以作为筛查健康青年人膈肌功能的一种方法。

环境温度对锂离子电池爆炸参数影响

为探究在不同环境温度下锂离子电池触发热失控后的燃爆危险性,利用改进的20-L球装置测试了锂离子电池在不同初始环境温度和加热功率下触发热失控后的爆炸参数,对爆炸后的气体取样并分析气体成分。结果表明,当初始环境温度为25℃时,随着加热功率增加,电池更早发生燃爆,最大压升速率增大,电池质量损失增大,损毁更为严重;当初始环境温度为60℃时,最大压升速率由14.41 MPa/s增加至29.12 MPa/s,表明初始环境温度对爆炸参数的测试结果有显著影响;当初始环境温度为95℃时,最大压升速率基本一致,最大压力略有下降;爆炸后的气体中均存在CO和H2,其体积分数随着初始环境温度的增加而增加,表明锂离子电池热失控产物并未充分燃烧。研究结果有助于更为全面地评估锂离子电池的燃爆危险性,为锂离子电池的安全防护提供数据参考。

1971-2022年河南省水汽压与能见度的时空分布及其关联

为探究河南省水汽压和能见度的时空分布特征和相关性,利用1971-2022年河南省118个国家级气象站的日最高水汽压和日最小能见度数据,分析了河南省年平均最高水汽压和最小能见度的时空变化特征及二者的相关性。结果表明:(1)年平均最高水汽压呈显著上升趋势,其气候倾向率达0.25 hPa/10a;最高水汽压在1998年发生由低到高的突变;豫中南、豫东及豫北水汽压上升最为显著;最高水汽压变化幅度大值区主要位于豫中南大部、豫西南部分县市。(2)年平均最小能见度呈显著下降趋势,其气候倾向率为-0.56 km/10a;最小能见度在2014年出现下降突变;豫西、豫西南、豫北部分县市及商丘、信阳局部能见度下降显著,变化幅度较大。(3)河南省大部分地区年平均最高水汽压与最小能见度存在显著的负相关(区域平均相关系数约为-0.41),水汽压升高(降低)易引起能见度降低(升高)。