沁水盆地南部山西组煤储层产出水的化学特征

Chemical characteristics of drainage water from Shanxi Formation coal reservoir of Southern Qinshui Basin

为研究沁水盆地南部柿庄南煤层气开发区块山西组3号主采煤层的地下水径流与水化学特征,从该区采集了煤层气井排出水样,对主要离子浓度进行测定,并分析离子浓度展布特征。研究结果表明:研究区水质类型以Na-HCO_3-Cl或Na-HCO_3型为主;由东向西呈现出水文径流区(氧化环境)到滞流区(还原环境)的过渡特征,受控于矿物溶解反应,KDS、Na^+、K^+、Cl^-、Ca^(2+)、Mg^(2+)、HCO_3^-等离子浓度由东向西逐渐增加,SO_4^(2-)由于脱硫酸效应呈相反变化趋势,高产井多分布于高矿化度、高离子浓度的区域,离子浓度与矿化度指示了研究区的地下水径流特征,可以作为判断煤储层水动力条件与开发有利区的参考因素。

In order to study the groundwater runoff and water chemistry characteristics of the No. 3 Shanxi Formation coal reservoir in Shizhuangnan Block,Southern Qinshui Basin,the authors collected water samples from coalbed methane wells. The characteristics of ion concentration were determined to analyze the distribution characteristics of ion concentration. The results showed that the water types of the water samples in study area were mainly Na＋-HCOa-C1 and Na＋-HCO3＋ type ; the study area had the characteristics of the transition from the runoff area （oxidation environment） to the residence area （reduction enviromnent） from east to west. The concentration of KDS, Na＋ , K＋ , C1-, Ca2＋ ,Mg2＋and HCO3 which increased gradually from east to west were controlled by mineral dissolution reaction,while under the concentrauou of S04 was gradually decreased. High production wells were mainly distributed in high salinity and high de sulfate effect,the . 2- ion concentration region. KDS and ion concentration indicated the characteristics of groundwater flow in the study area and can be used as reference factors for judging the runoff conditions of coal seam water and evaluating exploration target.