Lithologic and anticlinal gas reservoirs were developed in the Lower Permian Shanxi Formation and Lower Shihezi Formation in Shiguhao area of Yimeng Uplift

Ordos Basin.In order to study the hydrocarbon accumulation rules and optimize emplacement of horizontal wells

it is essential to analyze the geometries and types of the gas reservoirs.Based on drilling and seismic data in combination with identification of gas and water layers and test results

this paper analyzed the geometries on plane and sectional views of typical gas reservoir and researched the mainly factors that influence the sealing of gas reservoirs.Five types of gas reservoirs are recognized in the study area.In vertical

lithologic gas reservoirs are mainly developed in the P

1

x

2

and the P

1

x

3

anticlinal gas reservoirs are mainly developed in the P

1

x

1

stratigraphic overlapping gas reservoirs and structural-lithologic gas reservoirs are the predominant types in the Shanxi Formation.On the plane

lithologic and stratigraphic overlapping gas reservoirs are mainly developed in the slope belt of western Shiguhao area; anticlinal and structural-lithologic gas reservoirs are mainly developed in uplift belt of eastern Shiguhao area.Meanwhile

interlayer faults are well developed in Shiguhao area.In addition to small scale fault block gas reservoirs

some lithologic and anticlinal gas reservoirs are cut by interlayer faults

changing their geometries.By using three-dimensional seismic data

the geometries of gas reservoirs can be depicted accurately.