鄂尔多斯盆地白垩纪岩相古地理与地下水相关性探讨

岩石是地下水储存运移的重要介质，不同的岩石为地下水形成、储存与循环提供了不同的空间条件。岩相古地理反映了沉积环境中的古地理条件和沉积物特征中的岩性特征。沉积相对储层物性有明显的控制作用，不同沉积相内水动力条件不同，因而形成的砂体类型也不同，其岩性、粒度、分选、填隙物特征以及砂体的岩相组合、时空展布特征均有差异，结果导致不同相带内储集体物性特征各不相同。通过岩相古地理研究，能客观反映形成岩石的环境特征、岩石的纵横向展布及其物性特征，从而对区域地下水的水质、水量分布进行宏观预测和评价。本文即是基于此种思路对鄂尔多斯盆地白垩系岩相古地理与地下水相关性的研究。研究表明，沙漠相沙丘砂岩、辫状河道砂体、三角洲分流河道砂体、曲流河边滩砂体、滨岸带砂体是较好的储水体；沙漠相沉积的洛河组和盆地北部以冲积扇、辫状河沉积为主的环河组是其主要的含水层。

The correlation of sedimentary facies and palaeogeography and ground water from the Cretaceous strata in the Ordos Basin

The rocks in the crust always serve as the important media for the storage and migration of ground water. The accommodation spaces have changed with varying rock types. The sedimentary facies and palaeogeography tend to be the significant controls on the physical properties of the reservoir rocks. The differences of sandstone types generated under different hydrodynamic regimes are responsible for the differences of lithology, grain size, sorting, infilling, lithofacies association and spatio-temporal distribution. The study of the sedimentary facies and palaeogeography may help assist in the exploration of the environmental conditions, distribution and physical properties of the resultant rocks, and the prediction and evaluation of water quality and distribution of the regional ground water. The results of research in this paper show that the dune sandstones in the desert facies, braided channel sandstones, deltaic distributary channel sandstones, meandering channel point bar sandstones and (littoral) sandstones are good water-filled rock bodies. The Luohe Formation in the desert facies and the Huanhe Formation in the alluvial and braided stream facies may be delineated as major aquifers.