鄂尔多斯盆地富县探区上古生界天然气运移模式

鄂尔多斯盆地富县探区位于陕北斜坡，通过对该探区上古生界天然气初次运移的历史、动力、方向和二次运移方向的研究，认为该区上古生界在晚侏罗世一早白垩世开始大量生成天然气，为排烃的高峰期，初次运移的动力除扩散作用外，主要是气源岩所产生的异常压力，方向垂直向下，即指向奥陶系风化壳；天然气的二次运移方向主要是北东向，但由于地层倾角较小，横向进行二次运移的动力不足以及受储集层物性差和砂体展布方向等方面的制约，天然气只能在较短的范围内运移。富县探区是鄂尔多斯盆地上古生界天然气成藏的最佳地区。图6参8

Gas migration pattern of Upper Paleozoic in the Fuxian exploration area, Ordos Basin

Fuxian exploration area is located in Shanbei slope of the south Ordos Basin. The research of gas primary migration history, dynamic, direction, as well as secondary migration direction shows that the main generation of hydrocarbon was in the Late Jurassic-Early Cretaceous,and Early Paleozoic. Besides gas diffusion, the main factor of the primary migration is the abnormal pressure of the source rock with vertical direction, i.e., downward to the Ordovician weathering zone. Secondary migration is mainly to EN. Gas couldn't move further because of the slight slope and therefore the lack of dynamic for secondary migration, as well as the poor physical property and the restricted distribution of reservoir rock. This is the most promising area for gas exploration in Upper Paleozoic.