弱固结砂岩的岩石学特征及其地质意义—以柳江盆地太原组为例

Weakly Consolidated Sandstone Petrology Characteristics and Geological Significance—Taiyuan Formation in Liujiang Basin

摘要: 弱固结砂岩在我国分布广泛，引发了较多的环境问题和工程问题。本文以柳江盆地太原组顶部弱固结砂岩为研究对象，通过野外地质调查、偏光显微镜和扫描电镜及其能谱进行了分析。结果表明：(1) 弱固结砂岩分布于太原组煤层顶板上部，砂岩的弱固结化与煤的热变质演化具有成因联系。(2) 砂岩类型主要为灰白色中细粒长石石英砂岩，长石以碱性长石为主，发育高岭石化和伊利石化。黏土矿物主要为高岭石和伊利石，高岭石含量在13%~37%之间，伊利石含量在5%~7%之间，高岭石 + 伊利石组合储层敏感性表现为较强的速敏。(3) 矿物元素表明钾长石由Al、Si、O和K元素组成，高岭石由Al、Si和O元素组成，结合岩相学观察认为长石的溶蚀溶解作用为高岭石的形成提供了元素基础。(4) 该研究成果将为煤矿开采过程中地下水防治和矿山工程设计提供重要的地质信息。

Abstract: Miserably consolidated sandstone widely distributed in China, triggered more environmental and engineering issues. Taking Taiyuan Formation, Liujiang Basin miserably consolidated sandstone top for the study, field geological survey, polarized light microscopy and scanning electron microscopy and energy spectrum are analyzed. The results showed that: (1) poorly consolidated sandstone is located in the upper part of the Taiyuan Formation coal seam roof; thermal metamorphism of poorly consolidated sandstone and coal has a genetic link. (2) The main types of sand fines in an off-white medium fine grained feldspar quartz sandstone, feldspar alkaline feldspar, kaolinite and illite petrochemical development. Clay’s minerals are mainly kaolinite and illite, kaolinite content of between 13 to 37%, illite content between 5% - 7%; kaolinite Shiyi Li Shi Reservoir Sensitivity expressed through a combination of strong speed-sensitive. (3) The mineral elements indicate that the K-feldspar is composed of Al, Si, O and K elements, and kaolinite are composed of Al, Si and O elements, and the petrographic observation showed that the dissolution and dissolution of feldspar provide the basis for the formation of kaolinite. (4) The research results will be underground mine engineering design control and provide important geological information coal mining process.