基于岩相的鄂尔多斯白垩系盆地含水层系统结构的研究

Lithofacies-based study of the structure of the aquifer system of the Cretaceous Ordos basin, China

依据岩性岩相研究、孔隙度研究、物探测井解译等成果,对鄂尔多斯白垩系盆地含水层系统的结构进行了划分与研究。结果表明:盆地北部沙漠高原区含水层系统为单一结构,表现为强富水与中等富水含水层在垂向上叠置与组合,无区域性连续稳定的隔水层,由下到上构成含水统一体;南部黄土高原区为多层结构,表现为含水层与隔水层上下叠置,垂向水文地质分层明显;盆地南、北含水层的结构类型明显不同。利用孔隙度、渗透系数、单位涌水量3个参数,对含水层的富水性级别进行了划分,盆地中共划分出7个强富水含水层、7个中等富水含水层和2个弱富水含水层。盆地南、北比较,北部含水层孔隙度大,富水性强,地下水主要富集于盆地北部地区。垂向上比较,盆地北部由上到下,孔隙度由大变小,富水性由强变弱,地下水主要富集于浅层和中层;南部上部罗汉洞组和下部洛河组孔隙度较大,富水性好,中部环河组相对较差,地下水主要富集于罗汉洞组和洛河组。

based on lithologic, lithofacies, porosity and logging studies, the aquifer system in the Cretaceous Ordos basin may be classified into two subsystems, i,e, the single structure of the desert plateau in the north and the multiple structure of the loess plateau in the south, The structure characteristics of the two subsystems are notably different： the northern subsystem is a uniform aquifer from the top downward, marked by vertical overlapping and association of aquifers with large and moderate water storage capacities and no regional continued and steady aquifuge, By contrast, the southern subsystem is a separated hydrologic layer, characterized by overlapping of aquifers and aquifuges and pronounced vertical hydrogeological layering, The types of the northern and southern aquifer structures of the basin are markedly different, The water storage capabilities of the aquifers are classified, Altogether 7 aquifers with a large storage capacity, 7 aquifers with a moderate storage capacity and 2 aquifers with a small storage capacity are distinguished, Comparing the north and south of the basin, the aquifers in the north have a high porosity and a. The groundwater mainly concentrates in the north because the porosity in the north is higher and the storage capacity is larger than those in the south. In the north, the porosity changes from higher to lower and the water storage capacity turns from larger to smaller; so the groundwater mainly concentrates in the shallow and middle levels. In the south, the Luohandong formation in the upper part and the Luohe Formation in the lower part have higher porosities and larger water storage capacities, while the porosity and storage capacity in the Huanhe Formation in the central part are relatively poor; so the groundwater mainly concentrates in the first two aquifers.