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1.
山西省域煤系泥页岩孔隙分形特征 总被引：1，自引：0，他引：1
为定量化表征山西省域煤系泥页岩储层孔隙结构复杂程度,以山西省域140件海陆交互相煤系泥页岩实测低温液氮吸附数据为基础,利用FHH模型分别计算了孔径小于4 nm孔隙分形维数D_1与孔径大于4 nm孔隙分形维数D_2,结合XRD衍射、吸附甲烷、有机质丰度、类型等实验成果,讨论了孔隙结构、饱和吸附量、黏土矿物含量及有机质丰度与分形维数的关系。结果表明:山西省域煤系泥页岩发育有机质孔与无机孔,页岩有机质孔不及海相页岩发育,无机孔以黏土矿物层间孔与粒间孔为主,孔隙形态结构复杂,存在较多墨水瓶状、狭缝状孔;孔隙分形维数随BET比表面积、黏土矿物含量增高呈现出增大趋势,随有机质丰度、平均孔径及石英含量增高呈现出减小趋势;D_1与微孔及孔径为2～4 nm的介孔比孔容呈正相关关系,D_2与孔径为4～50 nm的介孔比孔容呈正相关关系,而与宏孔比孔容呈负相关关系;饱和吸附量与分形维数呈正相关关系;山西组泥页岩中黏土矿物含量比太原组高,分形维数与矿物含量的相关性比太原组好,太原组泥页岩w(TOC)高,但有机质孔发育不如山西组,D_1与w(TOC)的负相关关系比山西组更明显。 相似文献
2.
《地球科学进展》2016,(7)
在有限的条件下,为了更经济有效地评价页岩微观孔隙特征,同时利用扫描电镜(SEM)、氩离子抛光场发射扫描电镜(FESEM)方法对四川盆地彭水地区龙马溪组页岩孔隙特征进行了定性观察,并借助专业的图像分析软件Iamge J2x提取页岩SEM和FESEM图像蕴含的孔隙定量信息,结合统计学方法分析页岩全孔径分布特征,计算页岩孔隙分形维数,探讨孔隙结构特征以及分析维数与有机碳含量、矿物成分、孔隙吸附能力等的相关性,研究发现:扫描电镜下,彭水地区龙马溪组页岩微米级孔隙发育,主要孔隙类型有粒间孔、黏土矿物层间孔、粒内孔以及微裂缝等;氩离子抛光场发射扫描电镜下,可见大量纳米级孔隙,主要发育有机质孔、无机矿物孔(黄铁矿晶间孔、粒内孔、黏土矿物层间孔、粒间孔等)和微裂缝,两者综合分析更有利于页岩孔隙定性表征;页岩孔隙全孔径分布特征呈4个主峰,主要分布区间为3~9 nm,10~40 nm,100~400 nm,1~4μm;页岩有机质孔隙形状系数分布区间为0.9~1,孔隙呈圆形、近圆形,无机矿物孔形状系数分布在0.5~0.7,多呈三角形、多边形、狭缝形等,孔隙形状较有机质孔复杂,主要受页岩孔隙成因不同所致;彭水地区龙马溪组页岩孔隙符合分形特征,有机质孔隙分形维数较无机矿物孔分形维数小,孔隙结构相对简单;分形维数与有机质含量、矿物成分、孔隙度及吸附气含量都有一定的相关性,随有机质含量的增加,孔隙分形维数增加,孔隙结构复杂化,随分形维数增加,页岩孔隙的最大吸附气含量也随之增加,孔隙吸附能力增强。 相似文献
3.
柴北缘盆地YQ-1井中侏罗统石门沟组泥页岩纳米孔隙特征及影响因素 总被引：1，自引：0，他引：1
柴达木北缘(柴北缘)盆地侏罗纪是典型的陆相湖沼盆地,是目前具有页岩气潜力的盆地之一。本文运用氮气吸附、有机碳含量、有机质成熟度、全岩X衍射分析等方法,对柴北缘鱼卡地区YQ - 1井中侏罗统石门沟组泥页岩的纳米孔隙特征及控制因素进行研究。结果表明,石门沟组泥页岩纳米孔隙结构复杂,根据吸附回线及孔径分布特征可划分为两类,第一类以一端不透气性孔和开放性平行板状狭缝孔为主,孔径主要集中在3～5 nm范围内,呈单峰状分布;第二类则以一端不透气性孔和开放性倾斜板狭缝孔为主,孔径主要分布在3～5 nm和8～14 nm范围内,呈双峰状分布。孔径小于50 nm的微孔和介孔是比表面积和孔体积的主要贡献者;黏土矿物含量与微孔、介孔、总孔体积呈正相关;在较低的成熟度制约下,泥页岩有机质孔隙基本不发育,有机质丰度较高的石门沟组上段H9泥页岩TOC含量与微孔、介孔、总孔体积呈负相关性,有机质丰度较差的下段H8泥页岩TOC含量与孔体积相关性则不甚明显;孔隙结构及孔径分布受沉积环境水动力条件影响;黏土矿物是石门沟组泥页岩纳米孔隙的主要提供者,是孔隙发育的主控因素,TOC含量与沉积环境也会对泥页岩孔隙发育产生一定影响。 相似文献
4.
通过有机地化分析、全岩X衍射矿物分析、甲烷等温吸附及低压氮气吸附实验,本文对桂中坳陷环江凹陷上古生界页岩样品的孔隙结构及分形特征进行了研究.结果表明:研究区页岩总有机碳含量(TOC)平均为2.40%,热成熟度(Ro)平均为2.65%,处于过成熟演化阶段.页岩主要的矿物组成为石英和黏土.页岩的比表面积平均为5.86 m2/g,孔容平均为0.014 9 mL/g,平均孔径为11.2 nm.页岩中发育大量的中孔,主要呈两端开口的圆筒形孔或四边开放的平行板状孔.页岩中TOC含量和石英含量越多,微-中孔越发育、比表面积和孔容越大,而平均孔径则变小.通过Frenkel-Halsey-Hill (FHH)模型和氮气吸附实验数据计算得到孔隙表面分形维数D1(平均为2.428 4)和孔隙结构分形维数D2(平均为2.622 2),对应的相对压力(P/P0)分别是0~ 0.45和0.45 ~ 0.99.分形维数D1、D2随着比表面积、孔容的增加而增加,而平均孔径随着前者的增加而减小.分形维数D1、D2、TOC含量、石英含量和甲烷吸附量之间呈现较好的正相关性,但随着黏土矿物含量的增多而减小.分形维数D1与Langmuir压力存在弱负相关性,分形维数D2随Langmuir压力增大有变大的趋势.桂中坳陷西北部页岩分形维数越大,孔隙结构越复杂,其对天然气的吸附和存储能力越强. 相似文献
5.
贵州丹寨南皋下寒武统牛蹄塘组黑色页岩孔隙结构特征 总被引：1，自引：0，他引：1
页岩孔隙结构特征研究对页岩含气性评价具有重要意义。以上扬子东南缘南皋剖面下寒武统牛蹄塘组页岩储层为例,应用场发射环境扫描电子显微镜观察了页岩纳米级孔隙微观形态,通过低温氮气吸附法测定了页岩的氮气吸附等温线,并结合X-衍射矿物定量分析和有机碳含量测定,探讨了纳米级孔隙发育的控制因素。研究结果表明:矿物成分主要为黏土矿物(伊利石和少量绿泥石)、石英、长石、重晶石和石膏等。石英含量相对较高且沿剖面向上降低,wB平均为53%;相反,黏土矿物含量较低且沿剖面向上增加,wB平均为34%;碳酸盐矿物较少,仅在顶部可见。页岩主要发育粒内孔、粒间孔、裂缝和有机质孔4种孔隙类型,其中前两者较为常见。根据氮气吸附-脱附曲线、孔径分布特征、孔体积和比表面积可将样品划分为4类黑色页岩,孔隙以似片状颗粒组成的非刚性聚合物的槽状孔为主,前3类黑色页岩的孔径分布呈双峰形态,第4类黑色页岩的孔径分布呈单峰形态,最可几孔径分别为d≈0.9nm和d≈3.5nm。孔体积在0.002 8~0.024 3cm3/g之间,平均为0.014 7cm3/g,比表面积在1.056 8~28.825 0m2/g之间,平均为17.541 8m2/g,4类黑色页岩微孔频率分布依次减小,而介孔和宏孔频率分布逐渐增加,即微孔性逐渐变差,至第4类黑色页岩几乎只有宏孔孔隙。有机质丰度和矿物组分控制丹寨南皋牛蹄塘组黑色页岩的孔隙发育,其中有机质有利于孔隙发育且有机质微孔是孔体积和比表面积的主要贡献者;石英有利于孔隙发育,而黏土矿物则降低黑色页岩的孔隙性;它们均主要通过控制微孔和介孔的发育来控制黑色页岩的孔隙发育。 相似文献
6.
渝东南地区龙马溪组高演化页岩微纳米孔隙非均质性及主控因素 总被引：1，自引：0，他引：1
对页岩气赋存的主要场所页岩孔隙的研究是解决页岩气赋存和保存机理的关键,但目前缺少有效的手段去定量刻画高演化页岩微纳米孔隙的非均质性特征。通过低压N2吸附/解吸、高压压汞、场发射扫描电镜(FE-SEM)等实验,运用分形维数对渝东南地区龙马溪组高演化页岩微纳米孔隙非均质性进行了定量分析。结果表明：高演化页岩的微纳米级孔隙非均质性极强。中孔(2.0~50.0 nm)中2.0~4.5 nm 的孔隙分形维数平均2.853 4,4.5~50.0 nm 的孔隙分形维数平均2.7367,这种极强非均质性主要受有机质控制。总有机碳(TOC)含量大于1.7 %时,有机质孔在中孔中占主导地位,粘土矿物含量的增加会在一定程度上增加中孔的非均质性。宏孔(＞50.0 nm)分形维数平均2.8441,非均质性较强,主要受石英和碳酸盐等脆性矿物控制,随着碳酸盐矿物含量的增大,非均质程度增加,有机质对页岩宏孔的非均质性影响不明显。 相似文献
7.
为揭示陆相页岩微观孔隙结构特征,应用低温氮气吸附-解吸实验,结合扫描电镜分析、有机碳测定及X射线衍射等手段,分析页岩有机质和矿物组成,厘清孔隙结构和分形特征,并探究其影响因素。结果表明:沙河子组陆相页岩矿物组成以黏土矿物、石英和长石为主。储集空间类型主要为黏土矿物粒内孔、长石溶蚀孔和颗粒边缘孔,有机孔隙不发育。氮吸附曲线主要呈现为Ⅳ类吸附曲线,发育H2和H3两类迟滞回线,其中H3型比表面积较低,平均孔径较大,宏孔含量较高。页岩孔体积主要由介孔和宏孔贡献,比表面积主要由介孔贡献。孔径分布呈现双峰态,左峰约为2.7 nm,右峰分布在20~70 nm。页岩发育两段分形特征,分形维数显示H3型页岩孔隙结构非均质性及复杂性较弱。孔隙结构主要受矿物组成控制,与TOC无明显相关性,微孔含量与比表面积越高,宏孔含量与平均孔径越高,页岩孔隙结构越复杂,越不利于页岩气的运移及产出。陆相页岩因沉积环境控制下赋存的腐殖型有机质,从本质上影响了其孔隙空间、孔隙结构及页岩气富集特征,与海相页岩区别显著。 相似文献
8.
为了研究宁武盆地山西组过渡相页岩的孔隙特征和影响因素,对宁武盆地山西组过渡相页岩进行了系统采样,并针对性地进行了扫描电镜分析、低温氮吸附实验、TOC含量测试、有机质成熟度（Rmax）测试、全岩矿物X衍射分析和孔隙度测试,探讨了页岩孔隙类型、孔隙特征及影响因素。结果表明:研究区页岩孔隙类型主要以粒间孔、晶间孔、有机质气孔、有机质原生孔、溶蚀孔及裂缝为主,大小以2~50 nm的介孔为主,孔隙形态包括开放的尖壁形孔、平行壁孔、锥型管状孔、墨水瓶孔等;页岩平均孔隙度为3.64%,平均孔径为7.78 nm,BET比表面积平均为11.70m2/g,总孔体积平均为0.022 2 cm3/g,具有较强的储集性和吸附性;页岩孔隙具有分形特征,分形维数为2.61~2.77,分形维数与微孔体积分数表现出良好的正相关性;页岩孔隙发育受TOC含量、成熟度（Rmax）和矿物组成的影响。 相似文献
9.
为了评估下扬子皖南地区古生界页岩气储层性质,应用扫描电子显微镜、高压压汞法、N2和CO2气体吸附法,对皖南地区古生界页岩孔隙特征和孔隙结构进行研究,并探讨页岩孔隙发育的主要影响因素。结果表明,皖南地区古生界页岩孔隙度和渗透率低,页岩样品中常见粒间孔、凝絮孔、溶蚀孔、基质晶间孔和有机质孔,并且发育微米-纳米级孔隙。古生界页岩孔隙中50%以上为微孔和介孔;孔隙结构主要为圆柱孔、狭缝型孔和混合型孔,平均孔径范围为4.17~12.06 nm。页岩孔容和比表面积随着有机碳(TOC)含量的增大而增大;页岩孔隙度随着有机质成熟度(Ro)的增大而减小;页岩孔容随着黏土矿物含量的增加而增大,随着脆性矿物含量的增加而减小。 相似文献
10.
以渝东南-黔北地区牛蹄塘组页岩岩心及野外新鲜露头样品为研究对象,运用低温液氮吸附实验和氩离子抛光扫描电镜观察,划分页岩微纳米级孔隙类型,并对其发育程度和形态结构进行定量表征,结合页岩样品地球化学测试数据,明确页岩微观孔隙发育主控因素,试图建立微纳米级孔隙发育程度与主控因素定性或半定量关系。结果表明：研究区牛蹄塘组页岩微纳米级孔隙分为有机孔、无机孔和微裂缝3大类,包括7个亚类。有机质粒内孔结构特征为球状、细瓶颈状和墨水瓶状,无机孔主要为串珠状、球状和楔状,微裂缝呈四方开口的平行板状、夹板状。有机质粒内孔、矿物粒间孔和微裂缝为主要孔隙类型,且具有较好连通性,可作为页岩气赋存空间和渗流通道。页岩孔隙以中孔为主,其次为宏孔,孔隙直径分布范围主要在1~50 nm。比表面积主要由孔径≤5 nm孔隙所提供,页岩孔隙孔径越小,对比表面积贡献越大,越有利于页岩气吸附聚集,随着孔隙体积的增加,比表面积不断增加。有机碳含量是控制页岩微纳米级孔隙发育和比表面积的最重要内因,特别体现在对微孔和中孔发育的控制上;黏土矿物含量增加能增强页岩吸附能力,但对孔隙体积和比表面积主控作用不明显;脆性矿物含量主要控制宏孔发育,对页岩吸附的贡献可以忽略;热演化程度过低或过高均不利于有机质孔隙的发育,微纳米孔隙体积随着成熟度增加呈现出先增后减的趋势,对于高过成熟页岩,不同干酪根类型的有机质孔隙发育程度和比表面积大小次序为Ⅰ型＞Ⅱ型＞Ⅲ型。 相似文献
11.
为研究海相含煤地层页岩的微观孔隙特征,选取黔西北地区石炭系祥摆组页岩作为研究对象,利用扫描电镜(SEM)和液氮吸附实验研究孔隙特征,同时研究其分形特征,并探讨孔隙结构的影响因素。研究结果表明:研究区石炭系祥摆组页岩在扫描电镜下可观察到4类微观孔隙(粒内孔、粒间孔、有机质孔、微裂缝),其中微裂缝、有机质孔发育较丰富,具有较强的生成烃类气体能力和良好的储集性能;液氮吸附等温线在形态上呈反“S”形,表明中孔在微观孔隙中最为发育,滞后回线类型主要为H2型的细颈广体的墨水瓶孔;BJH总孔体积和BET比表面积值均较大,平均值分别为0.0155 cm3/g和13.20 m2/g,平均孔径为6.22 nm,纳米级微观孔隙大量发育,为烃类气体提供丰富的储集空间;页岩样品微观孔隙结构分形维数D较大,主体大于2.723 2,反映出孔隙结构复杂、非均质性较强;BET比表面积与TOC、石英含量呈一定的负相关性,与分形维数呈一定的正相关性;平均孔径值与石英含量正相关性较好,与分形维数负相关性较好,与黏土矿物含量呈一定的负相关性。石炭系祥摆组页岩微观孔隙的BET比表面积较大、平均孔径较小,微观孔隙结构较为复杂。 相似文献
12.
In order to evaluate the shale microscopic pore characteristics more economically and effectively in limited circumstances, the pore characteristics of Longmaxi Formation in Pengshui area, Sichuan Basin, were qualitatively observed and analyzed with Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) with argon ion polishing method at the same time. Pore quantitative information were extracted from shale SEM and FESEM images with the help of a professional image analysis software IamgeJ2x, and combined with statistical methods, the whole pore size distribution as well as shale pore fractal dimension and the relevance between fractal dimension and organic matter content, mineral composition and pore adsorption capacity and the corresponding pore structure characteristics of Longmaxi Formation in Pengshui area were analyzed. The study shows that under SEM, there are mostly micro pores of Longmaxi Formation in Pengshui area. The main pore types include intergranular pore, clay mineral layer pore, intragranular pore and micro cracks, etc. Through argon ion polishing FESEM, there mainly develop nanoscale pores. The main pore types contain organic pore, inorganic mineral pore (pyrite intergranular pore, intragranular pore, clay mineral layer pore and intergranular pore, etc.) and micro cracks. The use of both of the two methords is more advantageous to qualitatively analyze shale pore. The whole pore size distribution of shale pore has four main peaks and the main distribution range is 3~10 nm, 10~40 nm, 100~400 nm, 1~4 μm, respectively. The shape factor of shale organic matter pore is distributed between 0.9~1 and inorganic mineral pore is distributed between 0.5~0.7. It shows that the organic matter pore is circular, nearly circular and inorganic mineral pore shape is triangle, polygon, slit shape and so on. The inorganic mineral pore shape is relativly complex because of the different pore causes. The shale pore of Longmaxi Formation in Pengshui area conforms to the fractal features, and the organic pore fractal dimension is smaller than that of inorganic mineral pore, showing that the organic matter pore structure is relatively simple. There is a certain relevance between fractal dimension and organic matter content, mineral composition, porosity, and adsorbed gas content. With the increase of the organic matter content, the shale pore fractal dimension increase, the pore structure characteristics become complicated. With the shale pore fractal dimension increasing, the biggest gas adsorption quantity increases and the ability of pore adsorption strengthens. 相似文献
13.
Tianyi Zhao Xiangfang Li Zhengfu Ning Huawei Zhao Jinglun Zhang Wen Zhao 《Arabian Journal of Geosciences》2018,11(13):353
Knowledge of pore structure and adsorption capacity provides guidance for better studying the origin, hydrocarbon distribution, and productivity of shale gas reservoir. In this study, pore structure characteristics of six shale core plugs with different maturity from the Lower Silurian Longmaxi formation in south China were investigated using the Rock-eval analysis, X-ray diffraction, total organic carbon (TOC) content test, and scanning electron microscope (SEM) observation. To further investigate the influence of maturity, the adsorption behavior of gas shale was experimentally measured, with the maximal pressure being 20 MPa. Rock-eval analysis indicates that Ro is 0.67~1.34%. SEM results show that organic matter (OM) pores are abundant in high-maturity shale sample. The OM pores are mainly irregular to elliptical in shape, the size is 8~100 nm. The TOC content is 0.16~4.21% and shows a positive correlation with the BET surface area. A negative relationship exists between TOC content and average pore diameter, which indicates that abundant nanometer pores are related to the OM. A noticeable characteristic in the pore size distribution curve is that the content of micropores (pore width <?2 nm) increases with the increasing TOC content. Additionally, the thermal maturity results in significant difference in methane adsorption capacity. Maximal adsorption capacity of shale samples is also lineally correlated with TOC content, which increases with maturity. This study provides a quantitative understanding of how maturity affects pore structure and adsorption behavior of shale gas reservoir. 相似文献
14.
LI Xueyuan CHEN Shangbin WANG Xiaoqi ZHU Yanming CHANG Minghu Clementine UWAMAHORO 《《地质学报》英文版》2019,93(3):588-603
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. 相似文献
15.
页岩气储集空间与储层矿物特征关系密切,以四川盆地东缘龙马溪组页岩为研究对象,利用矿物组成、微量元素、地球化学等测试结果,结合低温氮气吸附法和高分辨率成像技术,采用多元统计分析方法,建立了页岩孔容预测方程,并分析孔隙分布特征和影响因素。结果表明,龙马溪组中部和底部页岩组分含量差异较大,生物成因的自生石英发育是龙马溪组底部石英含量高的主要原因;页岩纳米级孔隙以2~5 nm为主,对孔容贡献率介于64.2%~70.1%;建立的页岩组分含量与孔容的预测模型高度显著。脆性矿物孔、黏土矿物片间孔及其粒内孔是富黏土矿物页岩的主要孔隙类型,孔隙呈微缝状,小于2 nm孔隙不发育;有机质含量是富有机质页岩孔容大小的主控因素,有机质孔的面孔率介于8.8%~12.5%;有机质含量及成熟度是小于2 nm微孔发育的主控因素,大于50 nm孔隙的发育则受控于黏土矿物、石英及长石含量。 相似文献
16.
鄂尔多斯盆地长73亚段的页岩层系有机质含量、矿物含量变化大,发育凝灰岩夹层,具有较强的非均质性,不同岩相的孔隙结构差异及主控因素尚不明确。综合多种分析技术手段,对鄂尔多斯盆地南部长73页岩层系的岩相进行系统划分,对比不同岩相的孔隙结构及物性差异,探讨其有效孔隙网络及主控因素。根据粒度、TOC和矿物成分将长73细粒岩分为8种岩相类型,其中高有机质硅质页岩、凝灰岩及高有机质黏土质页岩三种岩相所占比例较高。长73页岩中有机质丰度高(平均20.04%),类型以Ⅰ型为主,处于低熟到成熟阶段。储集空间根据产状可分为基质孔隙(粒间孔、粒内孔、晶间孔、特大溶蚀孔)、有机质相关孔隙(有机质孔、有机质边缘孔隙)、裂缝(构造缝、成岩缝、晶面裂缝、粒边缝)。各岩相等温吸附曲线特征以IV型为主,迟滞回线以H3型为主。宏孔是储集游离油的有效孔隙,储集性能受岩相、有机质含量及矿物组成控制。凝灰岩孔隙度、渗透率及宏孔比孔容最高,其次为高有机质硅质页岩和高有机质黏土质页岩,而低有机质页岩宏孔比孔容最小,介孔比孔容大。页岩中有机质、黄铁矿含量与宏孔比孔容呈正相关,凝灰岩中石英含量与宏孔比孔容也呈正相关。研究成果可为长73亚段页岩油甜点评价及预测提供地质依据。 相似文献
17.
Based on 10 shale samples collected from 4 wells in Qinshui Basin,we investigate the full-sized pore structure and fractal characteristics of Marine-Continental transitional shale by performing organic geochemistry,mineralogical composition,Nitrogen gas adsorption(N_2 adsorption)and Nuclear Magnetic Resonance(NMR)measurements and fractal analysis.Results show that the TOC content of the shale samples is relatively high,with an average value of 2.44wt%,and the thermal evolution is during the mature-over mature stage.The NMR T_2 spectrum can be used to characterize the fullsized pore structure characteristics of shale.By combining N_2 adsorption pore structure parameters and NMR T_2 spectrums,the surface relaxivity of samples are calculated to be between 1.7877 um/s and 5.2272 um/s.On this basis,the T_2 spectrums are converted to full-sized pore volume and surface area distribution curves.The statistics show that the pore volume is mainly provided by mesopore,followed by micropore,and the average percentages are 65.04%and 30.83%respectively;the surface area is mainly provided by micropore,followed by mesopore,and the average percentages are 60.8004%and39.137%respectively;macropore contributes little to pore volume and surface area.The pore structure characteristics of shale have no relationship with TOC,but strong relationships with clay minerals content.NMR fractal dimensions D_(micro) and D_(meso) have strong positive relationships with the N_2 adsorption fractal dimensions D_1 and D_2 respectively,indicating that D_(micro) can be used to characterize the fractal characteristics of pore surface,and D_(meso) can be used to characterize the fractal characteristics of pore structure.The shale surface relaxivity is controlled by multiple factors.The increasing of clay mineral content,pore surface area,pore surface fractal dimension and the decreasing of average pore size,will all lead to the decreasing of shale surface relaxivity. 相似文献
18.
ZHANG Xu LIU Chenglin LI Bing WU Linqiang GUI Herong WANG Ziling ZHANG Zhihui LIANG Dexiu 《《地质学报》英文版》2020,94(2):337-351
The Songliao Basin is one of the most important petroliferous basins in northern China. With a recent gradual decline in conventional oil production in the basin, the exploration and development of unconventional resources are becoming increasingly urgent. The Qingshankou Formation consists of typical Upper Cretaceous continental strata, and represents a promising and practical replacement resource for shale oil in the Songliao Basin. Previous studies have shown that low-mature to mature Qingshankou shale mainly preserves type Ⅰ and type Ⅱ1 organic matter, with relatively high total organic carbon(TOC) content. It is estimated that there is a great potential to explore for shale oil resources in the Qingshankou Formation in this basin. However, not enough systematic research has been conducted on pore characteristics and their main controlling factors in this lacustrine shale reservoir. In this study, 19 Qingshankou shales from two wells drilled in the study area were tested and analyzed for mineral composition, pore distribution and feature evolution using Xray diffraction(XRD), scanning electron microscopy(SEM), low-pressure nitrogen gas adsorption(N2-GA), and thermal simulation experiments. The XRD results show that clay, quartz, and feldspar are the dominant mineral constituents of Qingshankou shale. The clay minerals are mostly illite/smectite mixed layers with a mean content of 83.5%, followed by illite, chlorite, and kaolinite. There are abundant deposits of clay-rich shale in the Qingshankou Formation in the study area, within which many mineral and organic matter pores were observed using SEM. Mineral pores contribute the most to shale porosity;specifically, clay mineral pores and carbonate pores comprise most of the mineral pores in the shale. Among the three types of organic matter pores, type B is more dominant the other two. Pores with diameters greater than 10 nm supply the main pore volume;most are half-open slits and wedge-shaped pores. The total pore volume had no obvious linear relationship with TOC content, but had some degree of positive correlation with the content of quartz + feldspar and clay minerals respectively. However, it was negatively correlated with carbonate mineral content. The specific surface area of the pores is negatively related to TOC content, average pore diameter, and carbonate mineral content. Moreover, it had a somewhat positive correlation with clay mineral content and no clear linear relationship with the content of quartz + feldspar. With increases in maturity, there was also an increase in the number of carbonate mineral dissolution pores and organic matter pores, average pore diameter, and pore volume, whereas there was a decrease in specific surface area of the pores. Generally, the Qingshankou shale is at a low-mature to mature stage with a TOC content of more than 1.0%, and could be as thick as 250 m in the study area. Pores with diameters of more than 10 nm are well-developed in the shale. This research illustrates that there are favorable conditions for shale oil occurrence and enrichment in the Qingshankou shale in the study area. 相似文献
19.
为了研究下扬子地区二叠系大隆组页岩孔隙结构特征,联合扫描电镜、高压压汞、N2/CO2气体吸附实验手段对页岩储层孔隙结构进行了研究。结果表明,研究区二叠系大隆组页岩孔隙类型以有机质孔、粒间孔、粒内孔、溶蚀孔和微裂缝为主;孔隙结构为多峰态-多尺度孔隙并存,微孔-介孔-宏孔都有发育,各个尺度的孔隙对孔容都有所贡献,其中以0.75～1.5 nm的微孔、10～35 nm的介孔及大于100 nm的宏孔为主。通过拟合孔体积、比表面积与埋深、有机碳(TOC)、成熟度(RO)以及矿物含量的相关性发现,微孔表面积与埋深、TOC呈正相关;微介孔体积和表面积均与RO呈负相关;宏孔体积与埋深、TOC、黏土矿物含量呈负相关,与RO呈较正相关;宏孔表面积与埋深成正比,与RO成反比。研究结果说明下扬子地区大隆组页岩孔隙发育主要受控于埋深、TOC、RO、黏土矿物含量等因素。 相似文献