| 渝东南—黔北地区牛蹄塘组页岩微-纳米级孔隙发育特征及主控因素分析 |
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| 引用本文： | 曾维特,丁文龙,张金川,李玉喜,王濡岳,久凯.渝东南—黔北地区牛蹄塘组页岩微-纳米级孔隙发育特征及主控因素分析[J].地学前缘,2019,26(3):220-235. |
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| 作者姓名： | 曾维特 丁文龙 张金川 李玉喜 王濡岳 久凯 |
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| 作者单位： | 海南省地质局,海南海口570206;中国海洋大学海洋地球科学学院,山东青岛266100;海南省地质调查院,海南海口570206;海南省海洋地质资源与环境重点实验室,海南海口570206;中国地质大学(北京)能源学院,北京100083;中国地质大学(北京)海相储层演化与油气富集机理教育部重点实验室,北京100083;中国地质大学(北京)页岩气勘查与评价自然资源部重点实验室,北京100083;自然资源部油气资源战略研究中心,北京,100032;中国石油化工股份有限公司石油勘探开发研究院,北京,100083;北京京能油气资源开发有限公司,北京,100022 |
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| 基金项目： | 国家自然科学基金项目(41272167，40672087，41372139，41072098)；国家科技重大专项专题(2016ZX05046-003， 2011ZX05018-001-002，2011ZX05009-002-205)；海南省博士后面上资助项目 |
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| 摘 要： | 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。
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| 关 键 词： | 渝东南一黔北 牛蹄塘组 页岩孔隙 微一纳米级 发育特征 主控因素 |
| 收稿时间： | 2018-07-11 |
Analyses of the characteristics and main controlling factors for the micro/nanopores in Niutitang shale from China's southeastern Chongqing and northern Guizhou regions |
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| ZENG Weite,DING Wenlong,ZHANG Jinchuan,LI Yuxi,WANG Ruyue,JIU Kai.Analyses of the characteristics and main controlling factors for the micro/nanopores in Niutitang shale from China's southeastern Chongqing and northern Guizhou regions[J].Earth Science Frontiers,2019,26(3):220-235. |
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| Authors: | ZENG Weite DING Wenlong ZHANG Jinchuan LI Yuxi WANG Ruyue JIU Kai |
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| Abstract: | We performed nitrogen adsorption isotherm and scanning electron microscopy (SEM) analyses on core and fresh outcrop samples of Niutitang shale from the southeastern Chongqingnorthern Guizhou region, which allow us to classify the micro/nano scale pore types and quantify the pores developmental stages and morphological structures. In addition, we carried out qualitative or semi-quantitative geochemical analysis on the controlling factors for the micro/nanopore development. The results show that the micro/nano scale pores in Niutitang shale can be divided into 3 types (including 7 subtypes): organic and inorganic pores and micro fracture. Structurally, the organic pore features spherical fine neck and ink bottle, the inorganic pore has bead, sphere and wedge features, and the micro fractures develops parallel plates with four-side opening and splint structures. The organic and intergranular pores and micro fracture are the main pore types, which could serve as storage space and seepage channels for shale gas with good connectivity. Shale pores are dominated by mesopores, followed by macropores, with pore diameters ranging from 1 to 50 nm. The specific surface area (SSA) is mainly provided by nanopores with diameters less than 5 nm, so that smaller pores make greater contribution to SSA and are more favorable for shale gas adsorption and accumulation, while SSA increases with increasing total pore volume. Our study further show that organic carbon content is the most important internal factor for controlling micro/nanopore development and SSA, particularly in controlling micro and mesopores. Moreover, increasing clay mineral content could enhance shale adsorption capacity, however, its controlling effect on pore volume and SSA is not obvious. The brittle mineral content mainly controls macropore development with negligible contribution to shale adsorption. For high and post mature shale, the order of organic pore development and specific surface area is type Ⅰ>type Ⅱ>type Ⅲ for different kerogen types. |
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