DISTRIBUTION CHARACTERISTICS OF PALEOPRESSURE IN THE LOWER PALEOZOIC OF THE ORDOS BASIN, CHINA

摘要

The Ordos Basin in China is a stable craton ba-sin. Previous studies on overpressure in the Ordos Basin have focused on Mesozoic and Cenozoic strata, but recent exploration results have shown that overpressure gas reservoirs have been discovered in the Lower Paleozoic Majiagou Formation in the eastern Ordos Basin. In this paper, the PetroMod ba-sin simulation software is used to simulate the paleo-pressure of 26 exploratory wells in the Ordos Basin. The results show that the Ordovician Majiagou For-mation in the Ordos Basin began to experience over-pressure in the Jurassic and reached its peak value in the Cretaceous. The paleo-pressure distribution of the Majiagou Formation is generally high in the east and low in the west. Among them, the paleo-pressure coefficient of the Mizhi area in the east is 1.5-1.7. which is a strong overpressure development area; the paleopressure coefficients of the Hengshan-Jing-bian-Ansai area in the central part are mostly distrib-uted in 1.3-1.4; the paleopressure coefficients of the Wushengi-Anbian-Wuqi area in the west are mostly distributed in the range of 1.2-1.4, so the overpres-sure development intensity in these areas is the weakest. The overpressure in the Majiagou For-mation is not a small-scaleregionaloverpressure, but a basin-level overpressure distribution.