In order to further reveal natural gas reservoir forming conditions and its main controlling factors in Shenmu gas field

Ordos Basin

this paper systematically analyzed the hydrocarbon generation conditions

reservoir characteristics

reservoir and seal conditions

source-reservoir-cap assemblage and key controlling factors of gas accumulation in the Taiyuan Formation by using theories of petroleum geology and hydrocarbon accumulation in combination with geochemical characteristics.The results indicate that Benxi Formation

Taiyuan Formation and coal seams in the 2

nd

member of Shanxi Formation are high quality source rocks for the Taiyuan Formation reservoir

and have high organic content which is favorable for hydrocarbon generation.The shale in the 2

nd

member of Shanxi Formation has dual sealing mechanisms (i.e.capillary seal and hydrocarbon concentration seal) with strong sealing capacity

which are favorable for hydrocarbon preservation.The reservoir lithology of the Taiyuan Formation is dominated by quartz sandstone and lithic quartz sandstone with low porosity and low to extra-low permeability due to the control of both provenance and sedimentation.However

local high-yield pay zones still exist due to the development of quartz sandstone reservoirs.Physical properties are the main factors controlling hydrocarbon accumulation of the Taiyuan Formation in this area.Mapping quartz sandstone distribution is the key to reduce drilling risk and to ensure high yield of gas wells.