松藻矿区地下水动力场特征及其对煤层气富集的影响

Characteristics of groundwater dynamic field and its effect on coalbed methane accumulation in Songzao mining area

松藻矿区是我国煤层气资源富集区之一。为揭示松藻矿区地下水对煤层气富集影响,利用煤田勘查获取的水文地质资料,基于含水层结构、水化学特征、抽水资料的系统分析,阐明了含煤地层上覆和下伏含水层地下水的空间展布特征,建立了地下水的分布模式,探讨了地下水动力场对煤层气富集的影响。研究表明:松藻矿区含水层和隔水层相互叠置,随着埋深的增加含水性减弱;含煤岩系与上覆、下伏含水层缺乏水力联系,为相互独立的含水系统;上覆长兴组和下伏茅口组地下水动力场呈南高北低展布;地下水动力场有近河流岩溶裂隙渗入型、断层沟通岩溶裂隙补给型、稳定承压弱含水型三种类型,以稳定承压弱含水型为主;含煤岩系的极弱含水性及其与上覆、下伏含水地层缺乏水力联系构成了区内水文地质控气基础,是研究区煤层含气性高的重要控制因素。

Songzao mining area is one of the most abundant coalbed methane resources in China.In order to reveal the characteristics of groundwater and its effect on coalbed methane enrichment in Songzao mining area,the hydrogeological data obtained from coal field exploration,based on the analysis of aquifer structure,water chemistry characteristics and pumping data,the distribution pattern of groundwater was established,and the influence of groundwater dynamic field on coalbed methane enrichment was discussed.The results show that aquifers are overlapped with each other in Songzao mining area,and the water content is weakened with the increase of the buried depth.The coal-bearing rock series and the overlying and underlying aquifers are lack of hydraulic connection and are independent of the water system.There are three types of groundwater dynamic field in Changxing Formation and Lower Maokou Formation,and the groundwater dynamic field has three types:karst fissure infiltration type,fault communication karst fissure recharge type,stable pressure weak water type,stable weakly aquiferous type is dominant,and the weak water-bearing property of coal-bearing rock series and its lack of hydraulic connection with overlying and underlying water-bearing strata constitute the basis of hydrogeological control of gas in the area,is an important control factor.