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.

Synthesis of Macro-Mesostructured γ-Al_2O_3 with Large Pore Volume and High Surface Area by a Facile Secondary Reforming Method

Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry(XRD), scanning electron microscopy(SEM), Fourier transform infrared(FTIR) spectroscopy and thermogravimetry(TG). The experimental results indicated that AACH and amorphous AlOOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume(2.175 cm3/g), high surface area(237.8 m2/g), and low bulk density(0.284 g/mL).

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.

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.

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。

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。

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。

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。

安塞地区长8段储层成岩作用及孔隙定量演化

通过铸体薄片鉴定、扫描电镜分析等方法,在储层基本特征、成岩作用与成岩序列分析的基础上,对安塞地区长8段储层的孔隙演化进行定量分析,建立储层孔隙演化模式。研究表明:压实作用对储层的破坏性最强,是储层致密的主要原因,减孔67.56%;胶结作用减孔23.65%,是储层在中成岩A期达到致密的关键;溶蚀作用则对储层物性具有一定的改善作用,在一定程度上延缓储层致密化的进程,增孔1.47%。孔隙演化在早成岩A期经历了快速压实—早期胶结阶段,在早成岩B期经历了压实减缓—早期溶蚀阶段,在中成岩A期经历了溶蚀—胶结致密阶段。该研究为安塞地区长8油层组下一步勘探开发提供依据。

利用高纯铝酸洗废渣制备大孔高比表面积拟薄水铝石研究

以硫酸铝、氢氧化钠及高纯铝酸洗废渣为原料,采用双铝法制备拟薄水铝石,研究了pH值、反应温度及尿素添加量对拟薄水铝石的形成及结构的影响与合成条件对拟薄水铝石形成时的物相及结构性能的影响。结果表明,随着反应温度升高,拟薄水铝石比表面积和孔容增大,结晶度提高。pH值6.5~9.5时,可以得到明显的拟薄水铝石物相;pH值达到10.5时,会产生三水铝石相。添加尿素能显著增加拟薄水铝石的比表面积和孔径。

脱气时间对中煤级煤低温氮吸附实验的影响

低温氮吸附法是目前用于评估直径在0.35 nm~300 nm之间煤的孔隙结构广泛使用的实验方法,通过实验得到的数据可以表征出煤的孔隙结构特征。在低温氮吸附实验中,样品的粒径、脱气温度和脱气时间等因素对实验结果影响较大。为研究脱气时间对低温氮吸附实验结果的影响,进行了一系列其他条件不变,只改变脱气时间的实验,选择的脱气时间分别为2 h,3 h,4 h,5 h,6 h,9 h,12 h,24 h。选取三种中煤级煤岩样品为实验材料,分别为济宁三号井气煤、张北矿气煤以及临涣矿焦煤。研究不同脱气时间下中煤级煤样在低温氮吸附实验中孔隙结构的变化,以确定最佳的脱气时间。通过分析煤样的吸附曲线、吸附-脱附曲线“滞后环”、阶段孔容曲线、平均孔径等参数,发现煤样在脱气时间发生变化时,煤样孔隙结构也发生相应的变化。研究发现,煤样在脱气时间为2 h和3 h时吸附-脱附曲线的类型以H3为主,其孔隙结构简单。煤样测定的平均孔径在脱气时间为3 h达到最大值,平均孔径在脱气时间为5 h达到最小值。在脱气3 h时,水分对煤样孔隙结构的影响可以忽略不计,挥发分对煤样孔隙结构的影响较低,此时煤样的孔隙结构更佳。三种中煤级煤样最佳脱气时间为3 h。

孔面积变化对孔盘式水力测功器影响的数值分析

为了探究静转子孔面积变化对孔盘式水力测功器性能的影响,利用数值计算的方法,对现有孔盘式水力测功器在不同孔面积条件下的内部流动过程进行分析,得到水力测功器腔室内部的流场和温度场,对比水力测功器进出口温差、流量、扭矩以及吸收功率等参数的变化。结果显示:静转子孔面积的增加会导致水力测功器进出口温差的增大,且大致呈线性关系,而流量的变化幅度较小,维持在20%以内。扭矩与吸收功率随孔面积增加而增大,且增大幅度逐渐减小,孔面积变化的影响不断减弱。

自密实混凝土早龄期孔结构演化及其强度形成规律研究

为保证水工混凝土构筑物在早龄期阶段的服役安全性,进行早龄期自密实混凝土力学性能和细观结构试验。制作100 mm×100 mm×100 mm的自密实混凝土试件,研究不同龄期(1 d、3 d、7 d、14 d、28 d)自密实混凝土立方体抗压强度的发展规律;分析龄期与自密实混凝土孔隙率、孔径分布之间的关系;构建龄期影响下抗压强度与孔隙率和T_(2)谱面积之间的数学模型。结果表明:自密实混凝土立方体抗压强度随龄期呈现非线性增长,且主要增长期为前7 d;随龄期发展,1号峰面积逐渐增大、2号和3号峰面积逐渐减小,自密实混凝土内部小孔隙(毛细孔)数量逐步增多且中、大孔隙数量逐步减少;1号峰面积和毛细孔孔隙率均与自密实混凝土立方体抗压强度呈正相关,且能更好地反映自密实混凝土强度的发展。随龄期增长,7 d之前毛细孔占比增长迅速,中孔和大孔占比减幅巨大,中、大孔均向毛细孔转变,28 d时内部结构中毛细孔占比达80%以上;毛细孔分形维数介于0.189~0.865,中孔分形维数位于2.881~2.977之间,大孔分形维数在2.906~2.998区间变化,整体上大孔分形维数明显大于中孔及毛细孔分形维数。

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。