Reservoir Characteristics and Controlling Factors on Upper Paleozoic Tight Sandstone Gas Reservoir in Ordos Basin ——By Taking Block Tao 2 in Sulige Gasfield for Example

In combination with the data of thin slice analysis,scanning electron microscopy,mercury intrusion curve and core analysis,the characteristics of tight sandstone reservoirs in the upper Paleozoic of Ordos Basin were deeply studied.The results show that the reservoirs in the studied area are mainly of lithic sandstone and lithic quartz sandstone.The main pore types are secondary intergranular pores and intragranular dissolved pore,intercrystalline pore and dissolved holes within the interstitial material are next.Coring data show that the average porosity is 8.6%and the average permeability is 0.62 mD.The reservoirs generally present the characteristics of low porosity and low permeability.The main controlling factors on the reservoir development are sedimentation,diagenesis and tectonic process.The sedimentation is the foundation,it not only determines the original composition and structure of the reservoir rocks and controls the reservoir distribution,but also affects the reservoir diagenesis at the late stage.The diagenesis is the key factor affecting the preservation of reservoir space,evolution and development,and ultimately it determines the quality of reservoir properties.Tectonics create cracks for the improvement of reservoir permeability.