Physical Property of the Upper Paleozoic Tight Sandstone Reservoir and Its Main Controlling Factors during Diagenesis of Well D18 in Daniudi Gas Field

Key words: 
• Well D18 /
• physical property characteristic /
• densification /
• cementation /
• favorable reservoir /
• dissolution

Abstract: Taking the Upper Paleozoic tight sandstone reservoir of Well D18 in Daniudi Gas Field as research object, utilizing microscopic methods and reservoir physical property data, we have performed researches on petrologic features, pore types, physical property evaluation characteristics, causes of densification and favorable reservoir main controlling factors. The analyzing results provide some indications. Firstly, Well D18 the Upper Paleozoic reservoir space is mainly dominated by secondary pore including quartz intergranular dissolved pore, quartz intragranular dissolve pore, intercrystal pore, rarely mold pore and oversized pore. Secondly, the reservoir belongs to low porosity and low permeability reservoir:the average porosity is 7.1%, and the average permeability is 0.34×10^-3 μm². Thirdly, compaction is the general background of reservoir densification; siliceous, calcareous and clay cements are the main causes of densification. Lastly, dissolution is the main controlling factor of Well D18 favorable reservoir, especially the quartz dissolution most growing; chlorite cementation can preserve primary pores without increasing reservoir physical property by enhancing the resisting compaction strength of rocks and inhibiting quartz over growth.