鄂尔多斯盆地侏罗纪含煤岩系地下水系统关键要素与格架模型

Key elements and framework model of groundwater system in Jurassic coal measures of Ordos Basin

  • 摘要: 地下水与含煤岩系矿产资源密切共生,直接制约含煤岩系矿产资源的合理开发和长远规划。鄂尔多斯盆地是我国重要的能源盆地,几十年勘查实践表明侏罗纪含煤岩系除具有5套(组)可采煤层外,还伴生有丰富的砂岩型铀矿、砂岩型高岭土和石英砂等矿产资源。基于已往对鄂尔多斯盆地的认知和经验,认为地下水的补给水源和输导通道是侏罗纪含煤岩系地下水系统结构中的关键要素。其中,潜在的地下水补给水源包含3套地下水储层(直罗组底部含水层、下白垩统洛河组含水层和罗汉洞组含水层)和地表水系;地下水输导通道则包含了区域规模的骨架砂体、不整合界面、断裂系统和人工采动裂隙系统等四大类型。含煤岩系矿产资源开发过程中遇到的“水害”,通常是原有的地下水系统被动揭露或者被破坏的表现,是人为因素连通了地下水水源与人工作业面从而导致地下水的泄漏。聚焦侏罗纪含煤岩系矿产资源的安全开发,一方面需要深入总结地下水系统关键要素的基本特征和分布规律,更进一步则需要揭示地下水系统关键要素与矿产资源的空间配置关系,并在此基础上构建含煤岩系地下水的格架模型,以此为煤系资源开发和矿井水害防治提供沉积学-水文地质学基础。在鄂尔多斯盆地,由于构造背景的差异,在不同地区地下水水源类型、输导通道类型、含煤岩系产状、矿产类型组合等都不尽相同,构成的地下水格架模型也因地而异,因此需要区别对待和深入研究。

     

    Abstract: Groundwater is often closely associated with coal resources,and directly restricts their rational development and long-term extraction planning. Ordos Basin is an important energy basin in China. The exploration practice for several decades shows that Jurassic coal measures has not only five sets of minable coal seams,but also is associated with abundant sandstone-type uranium deposits,sandstone-type kaolin,quartz sand and other mineral resources. Based on the previous knowledge and experience about Ordos Basin,it is considered that the supply source and transport channel of groundwater are the key elements of the groundwater system structure of Jurassic coal measures. Among them,the potential groundwater recharge sources include three sets of groundwater reservoirs ( the bottom aquifer of Zhiluo formation,the Luohe formation aquifer and the luohandong formation aquifer of Lower Cretaceous) and surface water system. The groundwater transport channel includes four types of regional scale framework sandstone body,unconformity interface,fracture system and artificial mining fracture system. The “water disaster” encountered in the mineral resources development of coal measures is usually the passive exposure or destruction of the original groundwater system,which is caused by human factors connecting the groundwater source and the artificial working surface. Focusing on the safe development of mineral resources of Jurassic coal measures,on the one hand,it is necessary to understand the basic characteristics and distribution laws of the key elements of groundwater system,and on the other hand,it is necessary to reveal the spatial distribution relationship between the key elements of groundwater system and mineral resources. On this basis,a framework model of groundwater in coal measures should be built so as to provide a sedimentology hydrogeology basis for the coal measures resource development and mine water disaster prevention and control.In Ordos Basin,due to the difference of tectonic background,the types of groundwater source,transport channel,coal measures occurrence and mineral type combination are different in different areas,and the groundwater framework model is also different in different areas,so it needs to be treated differently and studied in depth.

     

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