Br/Cl,I/Cl and chlorine isotopic compositions of pore water in shallow sediments：implications for the fluid sources in the Dongsha area,northern South China Sea

The Dongsha area is one of the most promising target areas for gas hydrate exploration in the South China Sea（SCS）.The study of pore water geochemistry has played a key role in Chinese gas hydrate exploration.Br/Cl,I/Cl and δ37Cl in pore water were applied here in tracing gas hydrate occurrence,chemical evolution of pore fluids and water/rock interactions in low temperature sediment environments.The samples were collected from Sites HD255 PC and HD309 PC in the Dongsha area in 2004.At Site HD255 PC,we found the elevated Br/Cl,I/Cl and decreased SO_4/Cl at the depth of 4–5 m,suggestive of a laterally migrated fluid probably generated from the gas hydrate occurrence.The range of δ37Cl is –0.54‰ to ＋0.96‰,and positive δ^（37）Cl at 4–5 m interval should be related with different diffusion rates between ^（35）Cl and ^（37）Cl.At Site HD309 PC,a laterally migrated fluid was also found at the depth of 3–4 m,with the Br/Cl two times to that of the seawater and decreased I/Cl,indicating the fluid has no relationship with the gas hydrate.In this site,the chlorine isotopic composition varies from –0.7‰ to＋1.9‰.Extra high Br/Cl might relate with the deep generated fluid.At higher temperature and pressure,the Br/Cl of the fluid is elevated during the hydrous silicate formation,while positive δ37Cl is also associated with the same mechanism.

A New Discovery on the Deformation Behavior of Shale Gas Reservoirs Affecting Pore Morphology in the Juhugeng Coal Mining Area of Qinghai Province, Northwest China

Objective The Juhugeng mining area in Qinghai Province of northwest China has attracted wide attention among geologists for it hosts typical coal measure gases.The shale gas reservoirs were reformed by intensive structural movements during geological periods,

Pore Structure Heterogeneity of the Xiamaling Formation Shale Gas Reservoir in the Yanshan Area of China: Evaluation of Geological Controlling Factors

Micro-heterogeneity is an integral parameter of the pore structure of shale gas reservoir and it forms an essential basis for setting and adjusting development parameters.In this study,scanning electron microscopy,high-pressure mercury intrusion and low-temperature nitrogen adsorption experiments were used to qualitatively and quantitatively characterize the pore structure of black shale from the third member of the Xiamaling Formation in the Yanshan area.The pore heterogeneity was studied using fractal theory,and the controlling factors of pore development and heterogeneity were evaluated in combination with geochemical parameters,mineral composition,and geological evolution history.The results show that the pore structure of the reservoir was intricate and complicated.Moreover,various types of micro-nano scale pores such as dissolution pores,intergranular pores,interlayer pores,and micro-cracks are well developed in member 3 of the Xiamaling Formation.The average porosity was found to be 6.30%,and the mean value of the average pore size was 4.78 nm.Micropores and transition pores provided most of the storage space.Pore development was significantly affected by the region and was mainly related to the total organic carbon content,vitrinite reflectance and mineral composition.The fractal dimension,which characterizes the heterogeneity,is 2.66 on average,indicating that the pore structure is highly heterogeneous.Fractal dimension is positively correlated with maturity and clay mineral content,while it is negatively correlated with brittle mineral content and average pore size.These results indicate that pore heterogeneity is closely related to thermal history and material composition.Combined with the geological background of this area,it was found that the pore heterogeneity was mainly controlled by the Jurassic magmatism.The more intense the magma intrusion,the stronger the pore heterogeneity.The pore structure and its heterogeneity characteristics present today are a general reflection of the superimposed geological processes of sedimentary-diagenetic-late transformation.The influence of magmatic intrusion on the reservoir is the main geological factor that should be considered for detailed evaluation of the Xiamaling Formation shale gas reservoir in the Yanshan area.

Model construction of micro-pores in shale: A case study of Silurian Longmaxi Formation shale in Dianqianbei area, SW China

Based on scanning electron microscopy and nitrogen adsorption experiment at low temperature, the pore types and structures of the Longmaxi Formation shale in the Dianqianbei area, SW China were analyzed, and a molecular model was built. According to mathematical statistics, the validation of the model was solved by converting it into a mathematical formula. It is found by SEM that the pores in clay mineral layers and organic pores occupy most of the pores in shale; the nitrogen adsorption experiment at low temperature reveals that groove pores formed by flaky particles and micro-pores are the main types of pores, and the results of the two are in good agreement. A molecular model was established by illite and graphene molecular structures. Moreover, based on the fractal theory and the Frenkel-Halsey-Hill formula, a modified Frenkel-Halsey-Hill formula was proposed. The reliability of the molecular model was verified to some extent by obtaining parameters such as the fractal dimension, replacement rate and fractal coefficients of correction, and mathematical calculation. This study provides the theoretical basis for quantitative study of shale reservoirs.

破孔面积对燃气弹射性能影响机理分析

为探究发射筒破损面积对燃气弹射过程的影响,采用RNG k-ε湍流模型、有限速率/涡耗散模型和动态分层网格技术,建立包含筒壁损伤的发射筒三维数值模型,在数值验证的基础上通过改变破孔直径,仿真得到不同破孔面积下发射筒内流场分布与内弹道参数。结果表明:在发射筒内部整体流场形态近似呈对称分布,但由于燃气产生附壁效应和旋转涡的出现,局部流场呈现非对称性;随孔径增大筒内压力减小,孔径为160 mm时,t_(0)时速度相比完整筒壁的速度下降高达13.17%,在设定的出筒条件下当孔径大于140 mm后不能满足出筒要求;进行各参数相关性分析时发现破孔面积与第一次压力峰值及t_(0)时速度之间呈负线性相关。

鄂尔多斯盆地吴起地区延长组长6段储层特征研究

为深入研究吴起地区延长组长6段储层地质特征,通过开展各类分析测试,对研究区储层孔隙结构特征和流体可动性进行了定量表征,系统分析了不同成岩作用强度与物性之间的关系。结果表明:研究区长6段储层岩石类型为长石砂岩,填隙物以铁方解石和绿泥石为主,储层物性较差,孔隙类型以残余粒间孔为主。储层孔隙结构可分为Ⅰ类、Ⅱ类和Ⅲ类,对应的孔喉大小、孔喉连通性和可动流体饱和度依次变差。研究区长6段储层压实作用中等偏强,压实作用主要是减小储层的孔隙空间,但对储层渗流能力影响较小;碳酸盐矿物和黏土矿物胶结均降低了储层物性,但绿泥石膜的存在可以有效保存储集空间;而溶蚀作用对储层物性的改善作用较小。以上成果对鄂尔多斯盆地吴起地区延长组储层综合评价和开发方案制定具有一定理论指导价值。

Pore-Throat Combination Types and Gas-Water Relative Permeability Responses of Tight Gas Sandstone Reservoirs in the Zizhou Area of East Ordos Basin, China

With the aim of better understanding the tight gas reservoirs in the Zizhou area of east Ordos Basin,a total of 222 samples were collected from 50 wells for a series of experiments.In this study,three pore-throat combination types in sandstones were revealed and confirmed to play a controlling role in the distribution of throat size and the characteristics of gas-water relative permeability.The type-I sandstones are dominated by intercrystalline micropores connected by cluster throats,of which the distribution curves of throat size are narrow and have a strong single peak(peak ratio>30%).The pores in the type-II sandstones dominantly consist of secondary dissolution pores and intercrystalline micropores,and throats mainly occur as slice-shaped throats along cleavages between rigid grain margins and cluster throats in clay cement.The distribution curves of throat size for the type-II sandstones show a bimodal distribution with a substantial low-value region between the peaks(peak ratio<15%).Primary intergranular pores and secondary intergranular pores are mainly found in type-III samples,which are connected by various throats.The throat size distribution curves of type-III sandstones show a nearly normal distribution with low kurtosis(peak ratio<10%),and the micro-scale throat radii(>0.5μm)constitute a large proportion.From type-I to type-III sandstones,the irreducible water saturation(Swo)decreased;furthermore,the slope of the curves of Krw/Krg in two-phase saturation zone decreased and the two-phase saturation zone increased,indicating that the gas relative flow ability increased.Variations of the permeability exist in sandstones with different porethroat combination types,which indicate the type-III sandstones are better reservoirs,followed by type-II sandstones and type-I sandstones.As an important factor affecting the reservoir quality,the pore-throat combination type in sandstones is the cumulative expression of lithology and diagenetic modifications with strong heterogeneity.

生物质碳材料的孔道分析

生物质碳材料的孔道类型和孔径大小制约着材料有效的活性位点数量,影响材料的性能。孔道分类又是孔径分析的前提条件,因此,建立孔道分类的方法非常有意义。随着生物质碳材料的深入研究,研究者对其孔道分析的要求逐渐提高。由于实际的吸脱附等温线具有不规则性,难以匹配IUPAC规范中的吸脱附等温线,所以,用实际的吸脱附等温线与IUPAC规范中的吸脱附等温线进行匹配对生物质碳材料的孔道进行分类准确度不能得到保证。使用自制生物质碳材料,运用物理吸附仪对其进行表征,采用BET方程(Brunauer-Emmett-Teller)、T-plot方法(Thickness-plot)、DFT方法(Non-local Density Functional Theory)、BJH(Barrett Joyner And Halenda)方法对其孔道进行分析。研究表明,采用孔隙率和比表面积占有率对其进行孔道分类,可以准确地定义出微孔生物质碳材料、介孔生物质碳材料和微介孔生物质碳材料,从而建立了孔隙率和比表面积占有率的孔道分类新方法。用标准样品对孔隙率和比表面积占有率的孔道分类新方法进行论证,结果一致。方法准确可靠、实用性高。

志丹-甘泉地区晚三叠世储层特征与成岩演化序列

为研究志丹-甘泉地区晚三叠世储层特征以及成岩演化序列,在岩芯、测井分析的基础上,采用普通压汞、恒速压汞等间接测定技术与核磁共振、微米CT等直接观测技术相结合的方式对储层的微观孔隙结构进行研究。结果表明:志丹-甘泉地区晚三叠世储层以次生孔隙为主,发育粒间溶孔、粒内溶孔、填隙物内溶孔及微裂隙,其中常见粒内溶孔,长石溶孔多伴随粒内溶孔发育,填隙物溶孔为少量浊沸石溶蚀形成的孔隙,微裂缝溶孔发育较少;普通压汞确定了志丹甘泉地区储层排驱压力、中值压力的最小值,计算了进汞饱和度值以及退汞效率;恒速压汞试验总结了不同渗透率储层的喉道分布特征,认为喉道是决定渗流率的主要因素;核磁共振T2谱的弛豫时间与储层的孔隙度呈正相关;微米CT技术构建了储层的孔隙网络模型,认为储层孔隙连通性较差。研究结果对志丹-甘泉地区延长组储层特征与成岩演化序列研究提供了理论依据。

Logging interpretation method for reservoirs with complex pore structure in Mesozoic-Cenozoic faulted basin around Daqing exploration area

In Mesozoic-Cenozoic faulted basin in the periphery of Daqing exploration area, the clastic reservoirs mainly consist of siltstone and gravel-bearing sandstone. The electrical conductivity of the reservoirs is complicated due to the complex pore structures, which cannot be accurately interpreted with commonly used model. In order to solve the problem, a three-water model has been applied in this study based on in-depth analysis of the conductive mechanism of rocks in the explored area, and favorable application results are achieved.

四川盆地PT1井区海相地层工程地质特征研究

PT1井区超深海相地层钻井过程中气侵和井漏频发,严重制约该区块的安全高效开发。文章基于有效应力法,利用最优化方法开展了海相地层孔隙压力评价;结合断层和裂缝发育程度探讨了PT1井区气侵和井漏纵横向分布特征。结果表明,受异常高压和裂缝发育程度的双重影响,气侵主要发生在龙潭组,占比达40%;井漏主要发生在筇竹寺组和灯影组,占总漏失量的80%以上。气侵与异常压力、裂缝发育程度、断裂情况等因素有关,异常高压是气侵内在的原因,而断裂带和发育的构造裂缝为气侵提供了必要条件。井漏层位和漏失量主要受一、二级大型断裂带控制,不同断裂带的影响具有显著的叠加效应,断裂带附近发育的构造裂缝为漏失提供了通道,距离F I7断裂越近越易出现漏失,且漏失量越大。研究成果为PT1井区钻井过程井下复杂预防和处理提供了科学支撑。

二氧化锡基染料敏化太阳能电池电子传输模型优化及器件性能研究

针对染料敏化太阳能电池(DSSC)而言,其光阳极的材料特性与设计参数对DSSC性能具有显著影响。为了深入研究这一影响,本文采用数值模拟的方式,以探究光阳极结构变化对DSSC性能的详细影响。但目前的数学模型不够完善且预测精度较低,因而本文在光电子传输理论和朗伯比尔定律的基础上,采用常数堆叠法和可变堆叠法将孔隙率对电子扩散系数的影响引入到DSSC的数学模型中,建立了更加完善且精确的电子传输模型,该模型能够更深入剖析光阳极结构参数变化对DSSC性能的影响。通过数值模拟了在不同孔隙体积、电子寿命、SnO_(2)涂层厚度及比表面积下DSSC的性能。结果发现:随着SnO_(2)薄膜孔隙体积的增加,太阳能电池的短路电流密度逐渐减小,而开路电压则呈增大趋势,这导致光电转换效率逐渐降低。当孔隙体积达到0.10 cm^(3)/g时,DSSC光电转换效率达5.16%,因此在保证电池刚性的前提下,尽量降低SnO_(2)的孔隙体积,有利于吸收系数和扩散系数的提升,这两个参数的提升有利于DSSC整体性能的提升,同时电子寿命的延长会带来太阳能电池短路电流密度和开路电压的增大,进而提升光电转换效率,当电子寿命达到200 ms时,光电转换效率达到5.82%。本研究通过详细的数值模拟分析,为优化光阳极结构从而提升DSSC的光电性能提供了有力的理论指导,有助于进一步推动DSSC的研究与应用。

内养护机制对再生混凝土材料宏、细观力学性能的影响研究

再生混凝土作为绿色生态混凝土,其在生态水利工程中的应用较为广泛。为提高其力学性能和耐久性,采用内养护方式将再生骨料预处理至干燥、半饱和、饱和状态,分别以50%、100%的取代率取代普通混凝土,并设置干燥状态的普通混凝土作为对照组,分析了不同取代率下含水量对再生混凝土宏细观性能的影响并对各参数进行相关性分析,通过建立再生骨料吸水、解吸模型从细观尺度诠释内养护作用机理。研究结果表明,同等取代率下,养护90 d时抗压强度较优异的是含水率50%的再生混凝土组。取代率增大,孔隙增多,养护90 d时,R50P、R100P的孔隙率比7 d时分别降低14.2%、10.3%,说明含水率50%的再生骨料能一定程度上改善孔隙和界面过渡区结构;骨料吸水、解吸过程中发挥的内养护作用机制是再生混凝土后期强度持续增长的主要原因。

淮南矿区1/3焦煤二次氧化煤样孔隙特性实验研究

采空区二次氧化煤样自然发火为煤矿安全生产带来了巨大隐患。以淮南矿业集团顾桥煤矿1/3焦煤为研究对象,利用实验研究的方法,系统研究了不同预氧化温度和预氧化时间对煤孔隙特性的影响,研究发现:新鲜煤样和不同预氧化处理煤样的等温吸附曲线均呈典型的第Ⅱ类等温吸附曲线;预氧化处理对煤中孔隙的影响主要集中在0.45~20 nm,其中,2~4 nm内微孔的数量和总孔容在减少,在4~20 nm内的孔隙的数量和总孔容则显著增大;煤样的比表面积随着预氧化温度的提升呈现出先增大后变小的趋势,并在70℃时达到最大值;预氧化处理后,孔径处于0.45~5.9 nm时,孔隙的数量和总孔容有较大的变化。研究成果可为采空区自然发火防控提供必要的科学理论支撑。

柴达木盆地马海东地区古近系砂岩储层微观孔隙结构特征及微观致密区成因

柴达木盆地北缘马海东地区古近系的油气勘探已经取得发现,但储层微观孔隙结构特征认识不清是影响油气勘探与开发的主要因素之一。为揭示马海东地区古近系砂岩储层微观特征,综合运用岩石薄片显微镜观察、X射线衍射(XRD)分析和压汞测试等试验技术,开展了低渗透砂岩储层的岩石学特征、物性特征、微观孔隙结构及各储层非均质性对比研究,用变异系数定量表征了储层非均质强弱程度。研究结果表明:①古近系砂岩储层以长石岩屑砂岩为主,填隙物主要为方解石。②路乐河组Ⅰ砂组储层孔隙度较大,下干柴沟组Ⅱ砂组储层孔隙度中等,路乐河组Ⅱ砂组储层孔隙度最小。③储层岩石经历了压实、胶结和溶蚀成岩作用,路乐河组Ⅱ砂组储层非均质性最强,路乐河组Ⅰ砂组储层非均质性最弱,下干柴沟组Ⅱ砂组储层非均质性介于两者之间。④富塑性岩屑纹层或富杂基的低渗砂岩为致密储层,方解石胶结和塑性黏土质岩屑变形是致密储层形成的重要原因。

泸州地区五峰组——龙马溪组页岩气成藏特征

为寻找四川盆地泸州地区五峰组—龙马溪组页岩气有利区,在开展流体包裹体检测、页岩微观孔隙观测、气泡变孔模拟等研究基础上,查明了泸州地区构造埋藏过程和生烃热演化过程,总结了泸州地区页岩气成藏特征和成藏规律。研究结果表明:泸州地区五峰组—龙马溪组富有机质页岩厚度大,在二叠纪—早三叠世生油,经历了中三叠世和燕山运动期—喜马拉雅运动期2次构造抬升,中三叠世抬升幅度有限,未导致大规模烃散失,燕山运动期—喜马拉雅运动期构造抬升晚于川东南且幅度小,利于页岩气保存;泸州地区五峰组—龙马溪组页岩有机孔发育,是由于中三叠世隆升时间短,强度小,未发生大规模排烃,大量液态烃保留在储集层中,有利于后期有机孔的大量形成,同时在晚三叠世—中白垩世,地层深埋发生液态烃裂解产气,地层广泛超压,有利于有机孔的后期保存;泸州地区三叠纪隆升虽然时间短、强度小,但是从模拟实验结果来看,可以导致原油稠化和气孔形成,对页岩气富集成藏有利。因此,发生在印支运动期的泸州地区的隆升造成原油稠化,有利于页岩气富集成藏;泸州地区地层抬升时间晚,页岩气散失时间短,低角度层理缝发育,而纵向裂缝少,均有利于形成超压页岩气富集区。提出的泸州地区五峰组—龙马溪组页岩富集成藏规律,对于指导其他同类型油气勘探具有借鉴意义。

干湿循环作用下红壤土孔隙结构与强度特性试验研究

【目的】周期性库水位升降使三峡库区消落带土体受反复干湿交替过程,为了分析干湿循环作用对土体的孔隙结构和强度特性的影响,【方法】针对三峡库区某滑坡消落带红壤土,开展反复干湿循环下的三轴试验和扫描电镜、核磁共振测试,分析干湿循环作用对红壤土微细观孔隙结构与强度特性的影响,研究土体孔隙结构演化规律及其与强度特性之间的关系。【结果】结果显示:干湿循环对消落带土体强度有明显弱化作用,随着干湿循环次数增加,土体剪切强度逐渐减小并趋于稳定;在干湿循环作用下,孔隙扩张向大孔隙演化,土颗粒间距增加,裂隙发育后团聚体崩解、分散为微小团聚体,孔隙间连通性增强,原有微观孔结构基本丧失,逐渐形成新的稳定孔隙结构状态。【结论】土体结构呈现明显的双重分形特征,土体黏聚力和内摩擦角与中巨孔隙分形维数呈现明显关联关系,干湿循环作用使中巨孔隙分布复杂程度降低,孔隙结构更松散,颗粒间咬合作用降低,黏聚力和内摩擦角减小。

多孔结构可磨耗涂层抗氧化性能评价方法

防钛火可磨耗封严涂层的抗氧化性能是决定其服役寿命的重要因素。然而,当涂层呈现孔隙率高达50%量级的多孔结构,经典的氧化增重评价方法不适用。为构建多孔结构涂层抗氧化性能的合理评价方法,以防钛火可磨耗封严涂层为典型的多孔结构合金涂层研究对象,通过系统研究涂层氧化动力学规律、氧化膜分布特征,揭示了多孔结构涂层内表面氧化机制,建立合理考虑涂层实际氧化表面积的多孔结构涂层抗氧化性能评价方法。结果表明,孔隙作为环境氧的快速扩散通道,使涂层与环境氧的接触面积增大2个数量级,导致根据经典氧化增重法所得氧化膜厚度比实际表面氧化膜厚度高2个数量级。据此,通过建模计算包含外表面和内表面的多孔涂层实际氧化面积,构建基于实际氧化表面积的涂层抗氧化评价方法。采用该方法评价NiCrAl-膨润土可磨耗封严涂层,得出600℃空气氧化条件下该涂层平均氧化速率为1.8×10^(-2) g·m^(-2)·h^(-1),达到标准HB5258—2000规定的完全抗氧化级。上述评价方法为准确评价多孔涂层抗氧化性能从而保障涂层可靠服役提供方法支撑。

微生物加固粉土的强度特性及加固机理研究

针对华北地区广泛分布的黄河冲积粉土级配差、强度低的问题,采用微生物诱导碳酸钙沉淀(MICP)技术对其进行加固。通过三轴试验研究加固粉土的强度特性,通过微观结构测试分析其微观机理;结合宏观现象和微观机理揭示强度加固机理。结果表明:MICP加固后粉土的强度得到了大幅提升;其黏聚力和内摩擦角均随加固轮数、胶结液浓度的增加而增大,且增长速率呈现出先快后慢的趋势;在胶结液浓度为0.5 mol/L、加固两轮时加固效率更高。就微观结构而言,土样中的孔隙随胶结液浓度和加固轮数的增大而逐渐减少;土样截面的平均非孔隙面积比随加固轮数、胶结液浓度的增加而增大;黏聚力、内摩擦角与平均非孔隙面积比之间均符合先快后慢的双线性增加关系。黏聚力与内摩擦角提升原因在于MICP加固生成的碳酸钙通过粘结粉土颗粒,填充堵塞颗粒间孔隙,使平均非孔隙面积比增大,进而提升土体强度。

铁尾矿人工湿地填料的制备及其成孔机理研究

为解决铁尾矿堆积问题,以铁尾矿和木屑粉为主要原料,制备出性能较好的铁尾矿人工湿地填料FITCWS。该填料焙烧前后的主要矿物成分由长石和角闪石转变为辉石。焙烧温度(T)、木屑粉用量(η)、木屑粉粒径(dw)和尾矿粒径(di)均可影响FITCWS的物理性能。T是影响吸水率和颗粒强度的主要因素,dw和di是影响比表面积和孔容的主要因素,dw、T和di是影响孔径的主要因素。T越高,FITCWS的颗粒强度越大,吸水率越低;dw和di越小,FITCWS表面的粗糙度越低,比表面积、孔容和孔径越大。制备FITCWS的优选方案是:η为0.3,T为1200℃,dw和di均为200~250目(58~74μm),所制FITCWS的吸水率为44%,颗粒强度为115.9 N,比表面积为6.932 m^(2)/g,孔容为0.017 cm^(3)/g,孔径为3.169 nm,孔形为通透的狭缝。