Geological and geochemical characteristics of the Middle–Lower Jurassic shales in the Kuqa Depression,Tarim Basin: an evaluation of shale gas resources

Middle–Lower Jurassic terrigenous shales constitute a set of significant hydrocarbon source rocks in the Kuqa Depression of the Tarim Basin. Until recently, however, most investigations regarding this set of hydrocarbon source rocks have mainly focused on conventional oil and gas reservoirs, and little research has been conducted on the formation conditions of shale gases. This research, which is based on core samples from nine wells in the Kuqa Depression, investigated the geological, geochemical, mineralogical and porosity characteristics of the shales, analysed the geological and geochemical conditions for the formation of shale gases, and evaluated the shale gas resource potential. The results show that the distribution of the Middle–Lower Jurassic shales is broad, with thicknesses reaching up to 300–500 km. The total organic carbon (TOC) content is relatively high, ranging from 0.2 to 13.5 wt% with a mean of 2.7 wt%. The remaining hydrocarbon generative potential is between 0.1 and 22.34 mg/g, with a large range of variation and a mean value of 3.98 mg/g. It is dominated by type III kerogen with the presence of minor type II₁ kerogen. The vitrinite reflectance values range from 0.517 to 1.572%, indicating the shales are in a mature or highly mature stage. The shales are mainly composed of quartz (19–76%), clay (18–68%) and plagioclase (1–10%) with mean contents of 50.36 wt%, 41.42 wt%, and 3.37 wt%, respectively. The pore spaces are completely dominated by primary porosity, secondary porosity and microfractures. The porosity is less than 10% and is mainly between 0.5 and 4%, and the permeability is generally less than 0.1 mD. These results classify the shale as a low-porosity and ultra-low-permeability reservoir. The porosity has no obvious correlation with the brittle or clay mineral contents, but it is significantly positively correlated with the TOC content. The maximum adsorbed gas content is between 0.82 and 8.52 m³/t with a mean of 3.37 m³/t. In general, the shale gas adsorption content increases with increasing the TOC content, especially when the TOC content is greater than 1.0%. The volumetric method, used to calculate the geological resources of the Middle–Lower Jurassic shales in the Kuqa Depression, shows that the geological resources of the Middle and Lower Jurassic shales reach 667.681 and 988.115 × 10⁹ m³, respectively with good conditions for the formation of shale gas and good prospects for shale gas exploration.     

湘中与湘东南岩关阶组和龙潭组页岩气潜力

为了揭示湘中与湘东南坳陷海陆过渡相页岩含气潜力及勘探方向,对该区下石炭统岩关阶组和上二叠统龙潭组泥页岩进行总有机碳含量TOC、镜质体反射率R_ran、干酪根碳同位素、有机质显微组成、X衍射、扫描电镜、孔渗特征和等温吸附等测试。结果表明岩关阶组和龙潭组处于成熟-高成熟期、类型以Ⅲ型为主;龙潭组泥页岩TOC含量普遍较高、而岩关阶组泥页岩TOC含量较低。龙潭组和岩关阶关组泥页岩矿物主要为黏土矿物和石英,部分含有较高的方解石。这两套页岩的孔隙发育较差,主要孔隙类型为有机孔、溶蚀孔和层间裂缝。孔隙度为0.41%~2.76%、渗透率为（0.08~0.98）×10-3 μm2。孔隙度主要受TOC控制,不稳定矿物如长石和碳酸盐岩虽然能提供一定孔隙,但对页岩物性的影响有限。泥页岩的甲烷吸附量普遍在1.67~2.5 cm3/g,2015H-D3井龙潭组泥页岩现场解吸气量普遍大于0.5 cm3/g,最高为2.35 cm3/g,表明湘中和湘东南地区龙潭组具有一定的页岩气潜力,但岩关阶组勘探前景相对较差。      

鄂尔多斯盆地东南部上古生界海陆过渡相页岩储集性与含气性

鄂尔多斯盆地上古生界海陆过渡相页岩是重要的页岩气富集层系,但是含气性及其控制因素研究薄弱,制约了对该地区页岩气的勘探和研究。论文通过对鄂尔多斯东南部本溪和山西组大量页岩样品开展有机地球化学、矿物组成、页岩孔隙及分布的研究,评价了海陆过渡相页岩的储集性;通过含气量现场解吸和等温吸附实验,分析了页岩含气特征和影响因素。结论认为研究区海陆过渡相页岩有机质丰度高(TOC含量0.5%~11%),主要发育III型干酪根,有机质成熟度较高(1.0%~3.0% Ro);矿物组成以富黏土页岩为特征,黏土矿物含量可高达60%以上。总孔隙度分布在2%~8%,部分样品微裂缝发育。孔隙类型以平行板状的狭缝型孔隙介孔为主,在岩石孔隙比表面积和孔体积的贡献占90%以上;TOC含量与孔隙比表面积及孔隙总体积具有密切的相关性,有机质孔隙对岩石总孔隙构成具有重要贡献。现场解吸含气量为0.591~4.05 m3/t,兰氏体积从0.05 m3/t到14 m3/t都有分布,页岩实测含气量与气体吸附能力差异大。TOC含量是控制海陆过渡相页岩含气量和含气能力的重要因素,富黏土矿物的吸附作用可使样品含气能力显著增加。     

皖南地区古生界页岩孔隙特征及影响因素

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(R_o)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。     

湘西北下古生界海相页岩储层特征与含气性分析

基于野外地质和钻井资料,结合相关实验测试结果,对湘西北地区下古生界海相页岩储层特征进行了深入研究,并探讨了页岩甲烷含气性及影响因素。结果表明：牛蹄塘组黑色页岩以深水陆棚斜坡相沉积为主,厚度范围为50~250 m;龙马溪组为闭塞海湾沉积,底部黑色页岩发育。两组页岩有机质类型均属于Ⅰ型,有机碳含量平均为3.57%和1.16%,热演化程度较高,平均达2.61%和2.08%。受沉积环境和成岩作用影响,两组页岩均具有高石英、低黏土、少量碳酸盐矿物的组成特征。页岩储集空间可划分为3大类：矿物基质孔、有机质孔、微裂缝。受有机质和黏土矿物等因素影响,页岩内部孔隙结构参数各不同,但主体上孔径小于50 nm的微孔和中孔提供了大部分比表面积和孔体积,为气体存储主要场所。牛蹄塘组页岩甲烷最大吸附量平均为1.98 cm3/g;龙马溪组页岩甲烷最大吸附量较低,为1.16 cm3/g。其中有机质与黏土矿物对页岩甲烷吸附量均有一定的贡献,而过高的成熟度和含水量可导致页岩吸附能力下降。     

Analysis of geological effects on methane adsorption capacity of continental shale: a case study of the Jurassic shale in the Tarim Basin,northwestern China

The Jurassic shale is an important source rock for the found gas reservoirs in the Tarim Basin, northwestern China, but has never been researched for shale gas potential. The geological effects on methane adsorption capacity for the gas shale have been investigated in this paper through the geochemical, mineralogical and adsorption analyses on samples from wells and sections. The methane adsorption capacity ranges from 0.58 to 16.57 cm³/g, and the total organic carbon (TOC) content is between 0.5 and 13.5 wt%. The organic maturity measured by T_max is between 410 °C (immature) and 499 °C (overmature). The methane adsorption capacity of the Jurassic continental shale in the Tarim Basin is affected by many geological factors, including the TOC content, organic matter maturity, mineral composition, surface area and pore size distribution. The TOC content is the most significant factor with a positive effect on the adsorption capacity of the Jurassic shale, and the influence varies piecewise according to the TOC content. The TOC content contributes much more to the methane adsorption capacity of organic‐rich shale samples (TOC content > 0.7 wt%) than to the organic‐lean samples (TOC content < 0.7 wt%). The mineral composition is a secondary factor, and the abundance of clay content has a positive effect on the methane adsorption capacity despite its relatively weaker adsorption ability compared to TOC. The pore size distribution has different effects on surface area and pore volume. Mesopores and micropores provide the major surface area and are mainly derived from TOC and illite, which has a positive influence on the adsorption capacity. Mesopores and macropores offer the major pore volume and are mainly formed by illite, which is the major contributor for pore volume rather than surface area. In addition, the TOC and illite contents of the Jurassic shale in the Tarim Basin are closely related to the origin, maturity and diagenesis evolution of the shale: (1) both TOC and illite content variations are related to the different provenances and depositional environments of shale; (2) the decrease of TOC content with increasing maturity is also partly attributed to hydrocarbon generation; and (3) the increase of illite content with increasing maturity is due to illitization in the diagenesis of shale. Copyright © 2015 John Wiley & Sons, Ltd.     

扬子地区下寒武统与下志留统黑色页岩孔隙度与有机碳关系差异性及原因

下寒武统牛蹄塘组与下志留统龙马溪组页岩是扬子地区发育的两套富有机质黑色页岩,由于其分布面积广、厚度大、有机质丰度高而成为页岩气勘探的重点层位.然而牛蹄塘组孔隙度表现出了与龙马溪组截然不同的规律,两套页岩的孔隙结构、有机碳含量、密度也存在显著差异.结合测井、埋深（上覆压力）、孔隙度、有机碳及成熟度测试数据进行了对比分析.结果显示,牛蹄塘组过高的有机碳含量和热演化程度严重影响了页岩的孔隙结构,使有机质碳化,有机质孔发生坍塌和充填;牛蹄塘组埋深大、上覆压力也大,导致无机孔被压实,因此其总孔隙度明显小于龙马溪组.      

海相页岩气储层特征研究进展与发展动态

富有机质泥页岩复杂的沉积成岩过程、细粒特征,以及远小于常规储层的以微米—纳米级为主的孔隙空间,给海相页岩气储层特征研究带来了极大的挑战。近年来借助多项先进技术方法的推广运用,在海相页岩气储层的多个方面形成了重要认识,页岩有机质与其成熟度关系密切,岩石矿物组分判定方法向定量化发展,岩相预测与建模技术得以应用,但成岩作用对储层的影响尚有待进一步探知,物性变化趋势的认识尚存在不同见解,孔隙结构实现了从定性到定量表征的跨越,页岩力学性质的解析能够有效指导压裂改造。通过进一步分析海相页岩气储层研究的发展动态,就页岩气储层孔隙结构系统表征、区域尺度上成岩与岩相变化的时空配置关系、成岩演化—岩相—孔隙系统—有机质丰度潜在的多元关系等研究方向作出了展望,以期推进储层特征研究在深度和广度上向前发展。     

A Combination of N2 and CO2 Adsorption to Characterize Nanopore Structure of Organic-Rich Lower Silurian Shale in the Upper Yangtze Platform, South China: Implications for Shale Gas Sorption Capacity

The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black shale from four wells in the Upper Yangtze Platform, and their TOC, mineralogical composition and pore characterization were investigated. Low pressure N2 and CO2 adsorption were conducted at 77.35 K and 273.15 K, respectively, and the pore structures were characterized by modified Brunauer-Emmett-Teller (BET), Dubinin-Radushkevich (DR), t-plot, Barrett-Joyner-Halenda (BJH) and density functional theory (DFT) methods and then the relationship between pore structure and shale gas sorption capacity was discussed. The results indicate that (1) The Lower Silurian shale has high TOC content of 0.92%–4.96%, high quartz content of 30.6%–69.5%, and high clays content of 24.1%–51.2%. The total specific surface area varies from 7.56 m2/g to 25.86 m2/g. Both the total specific surface area and quartz content are positively associated with the TOC content. (2) Shale samples with higher TOC content have more micropores, which results in more complex nanopore structure. Micropore volumes/surface areas and non-micropore surface areas all increase with the increasing TOC content. (3) A combination of N2 and CO2 adsorption provides the most suitable detection range (~0.3–60 nm) and has high reliability and accuracy for nanopore structure characterization. (4) The TOC content is the key factor to control the gas sorption capacity of the Lower Silurian shale in the Upper Yangtze Platform.     

阿尔金山前下—中侏罗统页岩气成藏地质条件分析

阿尔金山前侏罗系出露大套厚层的暗色泥页岩,生烃潜力优越,具备陆相页岩气形成条件,是有利的勘探接替区。通过野外地质调查、样品采集和测试分析,研究下—中侏罗统泥页岩的沉积展布、有机地球化学特征及储集性能,并探讨了该区页岩气的勘探潜力。研究表明: 富有机质泥页岩主要处于滨浅湖—半深湖相、沼泽相沉积环境中,其在平面上呈NE向展布,单层厚度和累计厚度均较大; 泥页岩的有机质类型主要为Ⅱ₁、Ⅱ₂型干酪根; TOC含量为0.55%~10%,平均为2.28%; 镜质体反射率(R_o)为1.0%~1.6%,平均为1.269%,处于成熟—高成熟阶段,为页岩气藏形成提供良好的生烃条件; 其矿物特征表现为脆性矿物含量高,大于51%,有利于后期的水力压裂改造和页岩气开采; 通过扫描电镜观察,泥页岩储层发育微孔隙及微裂缝,为页岩气提供了良好的储集空间和运移通道。初步预测,后期改造相对较弱的月牙山地区为页岩气勘探的有利目标区。     

阿尔金山前下—中侏罗统页岩气成藏地质条件分析

阿尔金山前侏罗系出露大套厚层的暗色泥页岩,生烃潜力优越,具备陆相页岩气形成条件,是有利的勘探接替区。通过野外地质调查、样品采集和测试分析,研究下—中侏罗统泥页岩的沉积展布、有机地球化学特征及储集性能,并探讨了该区页岩气的勘探潜力。研究表明: 富有机质泥页岩主要处于滨浅湖—半深湖相、沼泽相沉积环境中,其在平面上呈NE向展布,单层厚度和累计厚度均较大; 泥页岩的有机质类型主要为Ⅱ₁、Ⅱ₂型干酪根; TOC含量为0.55%~10%,平均为2.28%; 镜质体反射率(R_o)为1.0%~1.6%,平均为1.269%,处于成熟—高成熟阶段,为页岩气藏形成提供良好的生烃条件; 其矿物特征表现为脆性矿物含量高,大于51%,有利于后期的水力压裂改造和页岩气开采; 通过扫描电镜观察,泥页岩储层发育微孔隙及微裂缝,为页岩气提供了良好的储集空间和运移通道。初步预测,后期改造相对较弱的月牙山地区为页岩气勘探的有利目标区。     

湘西北地区寒武系牛蹄塘组页岩气资源前景

湘西北地区牛蹄塘组黑色页岩展布广泛,为寒武纪纽芬兰世—第二世滞留还原条件的沉积产物,适中的埋深和较大的厚度为其提供了良好的气藏条件。对其有机地化参数进行试验分析:TOC值为0.59%～13.05%,均值3.75%,有机质丰富;R_o值为1.87%～4.00%,均值3.05%,成熟度高;干酪根类型以Ⅰ型为主,少量为Ⅱ型,具有良好的生气潜力;矿物组成中脆性矿物含量为33%～87%,平均含量为68%,而黏土总量为13%～43%,平均为26%,脆性矿物/黏土矿物值高,有利于储层改造;页岩孔隙度为0.3%~8.0%,平均为3.3%,渗透率均小于0.04×10^-3μm²,为低孔低渗类型。综合研究表明,牛蹄塘组具有良好的页岩气生储潜力,同时运用条件概率体积法对其资源量进行评估计算,资源量十分可观。在此基础上对湘西北地区牛蹄塘组划分出6个页岩气有利区,为进一步实施页岩气勘查提供依据。     

China Shale Gas Reservoir Types and Its Controlling Factors

Shale gas is an important unconventional natural gas. This paper classified shale into three types, which are marine, marine-continental transitional and continental facies shales, and summarized strata, distributions and reservoir features of the three kinds of shales. Marine face shale usually occurs in large scale and great thickness, and has widespread distributions; transitional face shale has the characteristics of thin layers, large multiple thickness and frequent interbedding, while the distribution of terrestrial face shale is relative narrow. Different shale reservoirs have similarities in gas compositions, occurrence states, gas origins. But they also differ in thickness, distributions and rock associations, etc., because of different sedimentary environments. Comparing reservoir characteristics of Chinese and American shale, organic matter abundance, maturity and types control the gas generation; mineral compositions and structures, organic matter maturity and types, pore and fracture structures, gas occurrence and migration characteristics, burial depth, and effective thickness control the shale gas accumulation.     

页岩气储层孔隙类型及特征研究:以渝东南下古生界为例

通过薄片分析、扫描电镜及氩离子抛光技术,对渝东南下古生界含气页岩中的孔隙类型及特征进行了分类观察、描述,结合有机碳含量、X衍射、岩石物性、氮气吸附及甲烷等温吸附实验测试,分析了页岩气储层中各类孔隙的储气贡献,探讨这些孔隙对页岩中烃类运移的影响。研究认为,有机质孔隙、颗粒内孔、粒间孔隙及微裂隙是页岩气储层孔隙的4种类型,有机质表面的分散状孔隙多为nm级,石英碎屑可形成粒内或粒间孔隙,黄铁矿颗粒内部小晶体排列分布产生孔隙空间,黏土絮状沉淀形成片粒状结构孔隙,微裂隙普遍发育在页岩基质中,可达mm级。不同类型的孔隙能够为页岩气的赋存提供不同尺度的储集空间,页岩吸附含气量与表征孔隙特征的参数(TOC、BET比表面积、BJH总孔体积)具有显著的正相关关系。微裂隙与粒间孔隙对页岩中烃类的运移最有利。     

湘中涟源凹陷上二叠统龙潭组和大隆组海陆过渡相泥页岩孔隙结构特征及对比

以湘中坳陷涟源凹陷上二叠统龙潭组和大隆组海陆过渡相泥页岩为研究对象,重点选取12块典型泥页岩钻井岩心样品开展有机碳含量、岩石热解、X射线衍射、密度法孔隙度、高压压汞、二氧化碳和氮气吸附等测试分析,利用氩离子抛光-场发射扫描电镜（FE-SEM）观察了泥页岩孔隙特征,通过定性描述和定量测定相结合的方法研究了海陆过渡相泥页岩纳-微米级孔隙结构特征及孔隙发育影响因素.研究结果表明:龙潭组和大隆组泥页岩有机碳含量均较高,热演化程度处在凝析油和湿气生成阶段早期,对应R_o为1.22%~1.43%;泥页岩孔隙类型主要为粒间孔、粒内孔、有机孔和微纳米缝.龙潭组与大隆组样品在孔隙形态、孔隙大小和影响因素上均有差异:龙潭组样品氮气吸附滞回环开口宽,有机孔形态多为圆形和椭圆形,孔径较大;大隆组样品氮气吸附滞回环开口窄,有机孔形态多为不规则状,孔径较小;龙潭组泥岩和大隆组泥页岩样品有机碳含量与黏土矿物含量呈正相关关系,2套样品的微孔孔隙积体与有机碳和黏土矿物含量均呈正相关性;龙潭组样品介孔+宏孔的孔隙体积与有机碳和黏土矿物含量呈正相关性,与石英+长石含量呈负相关性;大隆组样品中的碳酸盐矿物对其孔隙性有明显影响,大隆组样品介孔+宏孔孔隙体积与有机碳、黏土矿物和石英+长石含量相关性不明显.      

陆相页岩微观孔隙结构及分形特征——以徐家围子断陷沙河子组为例

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。      

基于扫描电镜-氮气吸脱附和压汞法的页岩孔隙结构研究

研究页岩孔隙结构特征,对于探讨页岩气赋存机理有重要意义。本文采用扫描电镜(SEM)、氮气吸脱附法与压汞法对鄂尔多斯盆地页岩样品的孔隙结构进行了全面表征,发现所研究区域页岩孔隙类型包括溶蚀孔隙、粒间孔隙和微裂缝;孔径从几个纳米到几百个微米,BET比表面积在7~25 m~2/g之间,孔体积在0.01~0.03 cm~3/g范围。研究结果表明鄂尔多斯盆地页岩具有良好的孔隙结构,孔隙类型丰富,孔径分布范围广泛,其中纳米级孔隙占主导,纳米级孔的存在有利于页岩气的存储,微裂隙的存在则有利于页岩气的运移。说明该区域页岩气的储藏具有良好的基础环境,页岩含气量可能较丰富。     

金衢盆地上白垩统金华组湖相页岩油气地质特征

以金衢盆地白垩系金华组为研究对象,在钻井资料分析的基础上,结合区域沉积背景,通过分析暗色泥页岩有机质丰度、厚度和分布范围,研究和探索了金衢盆地上白垩统金华组湖相页岩油气地质特征。金衢盆地金华组湖相暗色泥页岩样品的有机质丰度特征表明,TOC值一般小于0.5%,属于非烃源岩,个别样品达到1.57%,属于优质烃源岩; 富有机质层段以富砂夹泥型或富泥夹砂型为主,具多产层特征,盆地北部凹陷具备一定的页岩油气勘探潜力。金华组湖相暗色泥页岩主要发育在西北部衢州—龙游沉积中心区,区域较为局限,厚度不均,范围5~100 m,平均孔隙度3.867%,平均最大渗透率0.087 2×10^-3 μm²,属于典型的致密型储层。将富有机质层段砂泥地层作为一个整体进行页岩油气勘探,源储一体是今后陆相页岩油气的重要勘探思路。     

川南地区筇竹寺组页岩微观孔隙结构特征及其影响因素

页岩微观孔隙结构是影响页岩气储层储集能力的重要因素。为评价川南地区下寒武统筇竹寺组页岩性质,基于井下 岩心样品、钻井资料,运用普通扫描电镜和氩离子抛光-场发射扫描电镜观测、Image J2x软件分析、低温CO2和N2 吸附、 高压压汞实验方法,对川南地区筇竹寺组页岩气微观孔隙成因类型、孔隙结构特征及其影响因素进行了研究。研究结果表 明,川南地区下寒武统筇竹寺组页岩孔隙度为0.25%~5.80%,平均为2.49%;发育多种成因类型微观孔隙,以粒间孔为 主,粒内孔、有机质孔和微裂缝次之,页岩微观孔隙总面孔率为3.58%~5.92%;川南地区筇竹寺组页岩总孔容为（2.86~ 12.55）×10-3 mL/g,总比表面积为2.727~21.992 m2/g,孔径主要分布于0.30~1.00 nm、2.5~4.7 nm和55~70 nm这三个区间,微 孔（<2 nm）和介孔（2~50 nm）是筇竹寺组页岩气储集空间的主体,孔隙结构形态主要为圆孔、楔形孔、平板狭缝型孔和混合 型孔结构。页岩孔隙度及总比表面积与TOC、脆性矿物含量呈正相关关系,页岩微孔孔容及比表面积与TOC呈正相关关 系,页岩孔隙度、总孔容及总比表面积与R0、粘土矿物含量呈负相关关系。     

川西南地区下寒武统筇竹寺组页岩气纵向差异富集主控因素

川西南地区筇竹寺组发育多套富有机质页岩,但上部优质页岩的含气性明显好于下部优质页岩.应用热解实验、物性测试、全岩矿物X衍射、低温氮气吸附、氩离子抛光-扫描电镜等方法对筇竹寺组页岩地化、储层、封盖条件等开展分析,揭示筇竹寺组页岩气纵向差异富集的主控因素.研究表明,页岩气差异富集的主要控制因素为:（1）页岩有机质富集程度:筇竹寺组上部页岩段TOC含量相对较高、分布集中,下部优质页岩段TOC含量较低且分布不均、分散,从而导致页岩纵向生烃物质条件、有机质孔隙发育及微孔（比表面）的差异.（2）页岩岩矿组成及储层特征:上部优质页岩段粘土含量高且以伊蒙混层为主,有利于吸附气富集,该页岩段以有机质孔隙为主,微孔相对比较发育但孔隙度较高,下部优质页岩以粘土矿物孔、脆性矿物粒间孔及微裂缝为主,介孔相对比较发育但孔隙度较低.（3）保存条件:上页岩段顶底板发育完整且岩性致密,对页岩气层具有较好的保护作用;下页优质岩段底部存在碳酸盐岩古风化壳,底板对页岩气的保存能力薄弱.因此,TOC含量高、粘土矿物含量高、有机质孔隙发育、顶底板条件好是决定上部优质页岩段含气性优于下部页岩段的主要因素.