沁水盆地南部煤层气藏水文地质特征

Hydrogeologic feature of coalbed methane reservoir in the southern Qinshui Basin

水文地质条件对煤层气的高产富集起到重要的作用。沁水盆地南部有多个水文地质子单元 ,存在地下分水岭 ,造成煤层气井气水产能动态复杂化。研究区东部边界晋获断裂褶皱带的北段有明显的横向阻水作用 ,南段地下水径流条件极差 ,不导水。南部边界的中段具阻水性质 ,对晋城一带煤层气的保存与富集起到了重要作用。西部边界以安泽为界 ,北段阻水 ,南段由导水断层组成。本区内部存在着 4条重要的水文地质边界。其中寺头断裂是一条封闭性的断裂 ,导水、导气能力极差。在沁水盆地的大宁—潘庄—樊庄地区 ,地下水以静水压力形式将煤层中的煤层气封闭起来。在寺头断裂西侧的郑庄及其附近地区 ,地下水径流强度可能较弱 ,较有利于煤层气保存。大宁—潘庄—樊庄一带为等势面“洼地”滞流型 。

Hydrogeologic condition is important for the high yield and enrichment of coalbed methane.Hydrogeologic unit in the southern Qinshui basin consists of lots of hydrogeologic subunits.Underground drainage divide results the gas- water yield performance complexity in coalbed methane wells.The northern interval of Jin- huo fracture fold belt on eastern boundary blocks the water in water- bearing beds in middle Ordovician formation horizontally,radial flow condition and water conductivity of underground water in southern interval is extrem ely poor.The water blocking property in middle interval of southern boundary is profitable for the preservation and enrichmentof coalbed methane in Jincheng.Western boundary is Anze,whose northern part is a water blockage boundary,southern part is water conducting fault.There are four important hydrogolgic boundaries in this area,in which Sitou fracture is a closed fracture whose water conductivity and gas conductivity is exceedingly poor.Underground water in terms of hydrostatic pressure encloses the coalbed methand in coalbed in Daning- Panzhuang- Fanzhuang district.It is profitable for the preservation and enrichment of coalbed methane that radial flow strength of underground water is probably weak in Zhengzhuang and nearby area of western Sitou fracture area.The enrichment condition of coalbed methane is good in Daning- Panzhuang- Fanzhuang district whose equipotential surface belongs to pothole stagnantpattern.