沁水盆地南部潘庄区块废弃矿井煤层气地球化学特征及成因

为了研究废弃矿井中煤层气成因，以沁水盆地南部潘庄区块废弃矿井为例，抽采废弃矿井中煤层气并进行化学组分和同位素测试，并采集部分废弃矿井水样品测试水中离子浓度、pH值等进行研究。结果表明:潘庄区块废弃矿井中煤层气CH₄体积分数平均值为91.99%，CO₂为1.26%，N₂为6.73%；甲烷碳同位素（δ13C₁）值为-31.36‰~-33.53‰，平均-32.25‰，氢同位素（δD）值为-182.76‰~-193.20‰，平均-187.538‰。废弃矿井排采水中阴阳离子主要为Mg2+、K+、HCO₃-、Cl-、Na+、SO₄2-和NO₃-等，产出水型为Mg-（HCO₃）₂型，表明矿井水受到地表水的强烈影响。废弃矿井中煤层气主要以热成因气为主，少量次生生物气。与附近未开采煤储层相比，研究区废弃矿井中的环境更有利于次生生物气的生成。 

Origin and geochemical characteristics of coalbed methane in abandoned coal mines,Panzhuang block,southern Qinshui basin

In order to analyze the carbon and oxygen composition and origin of the coal seam gas(CSG) in abandoned mines, Panzhuang block, south of Qinshui basin, in this paper, the coalbed methane and produced water samples were collected. The results show that the CSG of abandoned mines is dominated by CH₄, the average is 91.99%, with minor amounts of N₂(6.73%) and CO₂(1.26%). The δ13C values of CH₄ range from -31.36‰ to -33.53‰, with an average of -32.25‰, the hydrogen isotope(δD) value is between -182.76‰ and -193.20‰, and the average value is -187.538‰. The main ions in produced water of abandoned mine are mainly composed of Mg2+, K+, HCO₃-, Cl-, Na+, SO₄2- and NO₃-, and the type is Mg-(HCO₃)₂. The CH₄ was mainly generated from thermal cracking during coalification, with some microbial genetic methane. Compared with the unexploited coal seams, the abandoned coal mine is more suitable for methanogen to produce the CH₄.