Based on previous research data of sedimentary burial history

hydrocarbon-generating history

geothermal history

inclusion analysis

denuded thickness

deposition velocity

and etc.

in the northern Ordos basin

a study is initiated with the aim of understanding the pattern of abnormal pressure distribution

and the genesis and evolution of pressure in the Upper Paleozoic of the basin by combining its characteristics of universal low abnormal pressure

tight reservoirs

simple sturctures

dispersed gas pays

and compartment-controlled gas accumulation.The results confirm the existence of favorable geological conditions for developing compartments in the Upper Paleozoic of the basin.The Upper Paleozoic is recognized to be a complicate gas system with high and low pressure coexisted in compartments

i.e.the reservoir belongs to normal pressure-abnormal low pressure

while the mudstone still maintains high pressure.The study also suggests that the shape

inner structure

and sandstone-mudstone relationship of the compartment decide the distribution of gas reservoirs in the compartment.