Exploration achievements in the Southeastern Ordos Basin have attracted tremendous attention in recent years. However, few researches about distribution of formation pressure and relation with natural gas have been carried out in this area. The measured formation pressure data of 293 wells and well log data of 154 wells are analyzed in this paper, and the results show that the mudstones from Upper Shihezi Formation to Taiyuan Formation of Permian are mostly undercompacted, and that the variations with depth of formation pressure in 4 target layers have obvious differentiation, which can be divided into negative pressure system of Permian and normal pressure system of Carboniferous in further. The distribution of current formation pressure is high in the east and north and low in the west and south, the relation between sedimentary facies and distribution of formation pressure in Permian are in a good consistency. Gas reservoirs on vertical zonation are controlled by the under compacted mudstone layers, and also can be found in the "low pressure" areas of negative pressure stratum in Permian and "high pressure" regions of normal pressure in Carboniferous. The discovery of the relation between formation pressure and gas reservoirs is significant for the following natural gas exploration in this area.

formation pressure  /  natural gas distribution  /  Upper Paleozoic  /  Ordos Basin