扬子北缘中二叠统孤峰组不同岩性孔隙特征及其地质意义  

Pore Characteristics of Different Lithologies and Their Geological Significance from the Middle Permian Gufeng Formation in the North Margin of Yangtze

作　　者：梁西文[1] 吴勘[2] 马强分[3] 冯庆来[3] 喻建新[3] 

机构地区：[1]中石化江汉油田分公司勘探开发研究院,武汉430223 [2]中国地质调查局武汉地质调查中心,武汉430223 [3]中国地质大学地球科学学院,武汉430074

出　　处：《地质科技情报》2014年第3期78-86,共9页Geological Science and Technology Information

基　　金：国家自然科学基金项目(41272024);中国地质调查局项目(1212011220796);生物地质与环境地质国家重点实验室自主研究课题项目(GBL11302)

摘　　要：孔隙是页岩层系是否具有生烃能力、储气能力和开采价值的主要标志。采用场发射扫描电镜对鄂西建始扬子北缘中二叠统孤峰组硅质页岩、泥质灰岩和碳质页岩3类岩石采取二次电子模式扫描,发现并分析了5大类9小类孔隙,即①絮凝作用孔隙;②有机质化石孔;③有机质碎片沥青孔;④黄铁矿粒间孔;⑤矿物颗粒晶间孔;⑥微型通道;⑦微裂缝;⑧钙质化石孔;⑨碎屑与围岩之间孔。研究表明,硅质页岩中发育较多的黄铁矿微球粒以及絮凝结构,有机质孔隙从纳米级至微米级;泥质灰岩中以矿物质孔隙为主,微裂缝比较发育,脆性矿物多;碳质页岩中存在大量蜂窝状孔洞和广泛分布的微裂缝,孔隙类型主要为有机质纳米孔。碳质页岩与传统储层孔隙特征具有很大差异,是页岩气勘探最为有利的岩层。Porosity is the main aspect to evaluate the hydrocarbon generation capacity, gas storage capacity and exploitation value of shales. In this paper, we use field emission scanning electron microscopy to take the secondary electron mode to scan three types of shale from the Gufeng Formation in Jianshi, which are siliceous shale, argillaceous limestone and carbonaceous shale. Five categories and nine types of pores have detected, including： （1） porous floccules, （2） pores of organic matter fossils, （3） asphalt pores from organic matter debris, （4） pores of pyrite grains, （5） intercrystal pores within mineral grains, （6） micro- channels, （7） microfractures, （8） pores from calcium fossils, （9） pores between the debris surrounding rock. The main pore types in argillaceous limestone are intercrystal pores within mineral grains. Micro- fractures and brittle minerals are well developed. In siliceous mudstone, many pyrite microspherulites and floccules, organopores size from the nanoscale to several microns are found. A large number of honeycomb holes and microfractures are widely distributed in carbonaceous shale, the main pore types are organic mat ter nanopores. This shows that the nanoscale pore characteristics in carbonaceous shale differ from traditional reservoirs, which is the most favorable rock strata for shale gas exploration.

关 键 词：孤峰组 页岩气 孔隙 空间分布 资源评价 

分 类 号：P618.130.21[天文地球—矿床学]