Reservoir properties and genesis of tight sandstones—A case study from the Gaotaizi oil layer in the Qijia area, Songliao basin

The primary focus of oil and gas exploration for tight sandstone reservoirs is on a quantitative characterization reservoir properties. This paper uses the developed in Gaotaizi layer Qijia area Songliao Basin as an example. petrology, physical properties, pore–throat characteristics, genesis densification oil-bearing sandstones are elucidated using casting thin-sections, scanning electron microscopy, 3D computerized tomography (CT), petrophysical experimental techniques. results show that mainly composed clastic rocks contains small amounts shell limestone. lithic feldspar sandstone, while residual intergranular pores, dissolved intragranular pores intercrystalline constitute different pore types. Mercury intrusion analysis showed micro-nano account 53% total present. coordination number distributed between 1 4, with average 1.8. throats have poor connectivity. porosity distribution 1.4%–22.5%, 9.5%, permeability ranges from 0.01 to 27.10 mD, 0.41 mD. It ultra-low reservoir. divided into three types through systematic study its developmental characteristics. Diagenetic processes like compaction cementation result reduction permeability. Compaction, calcite siliceous cementation, illite packing primarily responsible densification.