米仓山—汉南隆起区牛蹄塘组页岩矿物组分与微观孔隙的关系  

Relationship between mineral composition and micro-pores of Niutitang-Formation shale in Micangshan-Hannan Uplift

作　　者：田涛[1,2,3] 付德亮 杨甫 段中会[1,2] 蔺亚兵 赵雪娇[1,2] TIAN Tao;FU Deliang;YANG Fu;DUAN Zhonghui;LIN Yabing;ZHAO Xuejiao(Key Lab of Coal Resources Exploration and Comprehensive Utilization,MLR,Xi＇an 710021,China;Shaanxi Coal Geology Group Co.,Ltd.,Xi＇an 710021,China;Key Laboratory of Petrole,Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]国土资源部煤炭资源勘查与综合利用重点实验室,陕西西安710021 [2]陕西省煤田地质集团有限公司,陕西西安710021 [3]中国科学院地质与地球物理研究所兰州油气资源研究中心,甘肃兰州730000

出　　处：《煤炭学报》2018年第B06期236-244,共9页Journal of China Coal Society

基　　金：陕西省重点研发计划资助项目(2017GY-150)

摘　　要：利用米仓山—汉南隆起区牛蹄塘组暗色泥页岩样品,进行X射线衍射、低温氮气吸附、氩离子抛光-场发射扫描电镜等实验,结合有机地球化学参数,探讨矿物组分对微观孔隙结构的影响。研究结果显示,米仓山—汉南隆起区牛蹄塘组页岩矿物组分复杂,以石英和黏土矿物为主,平均含量分别为41.35%和31.55%,其次为长石、碳酸盐矿物、黄铁矿,脆性指数集中分布在0.6~0.8,具有良好的脆性和可压性。石英、长石等脆性矿物提供纳米级粒边缝隙、少量粒间孔和溶蚀孔;黏土矿物提供了大量的顺层缝隙、泥粒孔和片间缝隙;有机质中普遍发育气孔、边缘缝隙、铸模孔等多种孔隙类型。比表面积、孔体积与黏土矿物含量具有良好正相关性,而与石英、长石含量关系不明显,有机质含量与孔比表面积具良好正相关性,而与孔体积关系较差。结果表明,黏土矿物对牛蹄塘组页岩微孔-介孔-大孔发育有主控作用,而有机质则主要是微纳米孔发育的载体;黄铁矿通过自身孔隙结构特征及其与有机质相互影响,对页岩微观孔隙发育起到先促进后抑制的作用,作用转换阈值可能为2.8%左右。Based on the shale samples from Niutitang Formation in Micangshan-Hannan Uplift,some technical experimental devices,such as X-ray diffraction（ XRD）,low-temperature nitrogen gas adsorption and argon ion figuring-field emission scanning electron microscope（ Ar-FESEM） were used to analyze the relationship between mineral composition and micropore structure of Niutitang-Formation shale.The results show that the mineral composition of Niutitang-Formation shale in Micangshan-Hannan Uplift is complex.The mineral composition are mainly quartz and clay minerals,then feldspar,carbonate minerals and pyrite,and the average content of quartz and clay minerals are 41. 35% and31. 55% respectively.The brittleness index（ BI） of Niutitang-Formation shale distributes mainly in the range from 0.6 to 0.8 that demonstrate a good compressibility and brittleness. Some nano-sized fractures are along the edge of particles,and few intergranular pores and dissolved pores are formed by quartz and feldspar. There are lots of beddingcracks,pores among clay particles and cracks between schistose minerals formed in clay minerals.Multiple types of micropores are developed in organic matter,such as pores by hydrocarbon expulsion,fractures between organic matter and other minerals and mold pores. The BET and micropore volume have the positive correlation with the content of clay minerals and organic matter,but not with the quartz and feldspar.And the TOC has a positive correlation with BET but not with micropore volume.Also,the results show that the clay minerals are the main influences on the development of macropores,mesoporous and micropores of Niutitang-Formation shale. However,TOC is the main carrier of micropore which means the macropores and mesoporous are not well-developed in organic matter.The pyrite inhibits the growth of micropore after promoting it due to its own unique pore space structure and interaction with organic matter,and the functional mechanism changes when the content of pyrite increases up to 2.8%.

关 键 词：米仓山—汉南隆起 牛蹄塘组 页岩 矿物组分 微观孔隙 

分 类 号：P618.13[天文地球—矿床学]