鄂尔多斯盆地中部中生界地下水动力系统

Analysis on groundwater hydrodynamic systems of the Mesozoic in the central Ordos Basin

地下水是油气运移的载体,地下水赋存状态必将影响盆地中油气的运移、聚集和分布规律,正确划分地下水动力系统对油气田勘探和开发具有重要的指导意义。通过分析鄂尔多斯盆地中部上三叠统延长组至白垩系的现今地下水压力场、化学场和同位素特征,尝试性地划分出3种不同性质的地下水动力系统:浅部相对开启带、中部过渡带和深部相对封闭带。深部相对封闭带对油气藏的保存条件最为有利,是油气勘探的有利目标区域。

Groundwater serves as the carrier for hydrocarbon migration. The modes of groundwater occurrence have an effect on hydrocarbon migration, accumulation, and distribution in a basin. Therefore, a correct division of groundwater hydrodynamic systems can be a useful guidance for hydrocarbon exploration and development. The analyses of the present groundwater pressure field, geochemical field and stable isotope features of the Mesozoic （T3y-K） in central Ordos Basin revealed three kinds of groundwater hydrodynamic systems of various characteristics. They are the relative open zone in the shallower part, the transitional zone in the middle part, and the relative confining zone in the deeper part. The relative confining zone in the deeper part has the most favorable conditions for hydrocarbon preservation and can be the target for future exploration.