韩城地区构造煤类型与孔隙特征

The types of tectonic coals and pore characters in Hancheng

利用扫描电镜、压汞法、低温氮吸附和等温吸附试验对韩城地区煤岩样品的综合分析,探讨了韩城地区构造煤孔隙特征。研究表明:同一煤级,碎裂煤层理、裂隙发育,在富水文地质单元等条件影响下多被矿物质充填,孔隙连通性变差;碎粒煤、糜棱煤显微构造、外生裂隙发育,气孔大量出现促使渗流孔隙显著恢复,隔水性能强造成矿物质变少,孔隙连通性变好,渗流能力提升;不同煤体结构的煤孔隙均以吸附孔(微孔)占据主导地位,孔径介于1～100 nm的孔占71.436%～88.152%,其中微孔含量很大,占74.56%～94.70%;同一煤级,随构造变形程度加大,中孔比例增大,开放型孔逐步转化为细瓶颈型孔,碎裂煤微孔比表面积0.002 7 m2/g,糜棱煤增至7.479 0 m2/g,微孔对煤孔隙结构参数影响逐渐占据主导作用。

Using scanning electron microscope,low-temperature nitrogen and isothermal adsorption,coal sample of Hancheng were tested and analyzed,and pore structure for tectonic coals was discussed.The results indicate that in the same coal rank,stratification and crack are well developed in cataclastic coal,which is mostly filled by mineral substance in the geohydrologic element abundance,results in pore connectivity variation.Granulated and mylonitic coal being of these characteristics,as develope microstructures and exogenous fractures as well as large quantity of pores resulted from gas generation and strong impermeability,stimulate the recovery of seepage coal,improve coal connectivity and enhance reservoir permeability.Absorption pore（micro-pore） is dominant in coal pore for different coal body structure,the percent of which pore aperture is from 1 to 100 nm is 71.436% to 88.152%,including large of micro-pore with the 74.56%~94.70%;with the deformation becoming more intense in the same coal rank,mesopore enlarge further,open-end pores become thin-neck-bottle-shaped pores step by step,specific surface area of micro-pore for cataclastic coal is 0.002 7 m2/g,while mylonitic coal increases to 7.479 0 m2/g,micro-pore gradually play a dominant role in effecting pore structural parameters.