He 8 and Shan 2 plays in the study area have the characteristics of and conditions for accumulation of deep basin gas. The reservoirs are characterized by high compactibility

sporadic water production in gas-bearing area and strong compartmentalization of gas reservoir pressure

mainly due to continental sedimentary sequence and later reconstruction of gas reservoirs. Geologic analysis and physical modelling show that sandbodies have regional connectivity (along) strike

thus migration and accumulation processes of gas displacing water might occur in reservoiring conditions. A development stage and a reconstruction stage of deep basin gas can be divided at the end of Early Cretaceous. Reservoir pressure evolved from overpressure to underpressure in the reservoiring process. The main factors that caused the pressure drops in different areas are not the same. In Suligemiao area

it is mainly caused by the enlargement of dissolution pores in reservoirs

and temperature drop also has certain influences. While in Yulin and Shenmu-Mizhi areas in eastern Ordos Basin

it is mainly caused by the uplifting and temperature drop.A specific reservoiring pattern is presented based on comprehensive analysis of reservoiring features and process.