Micro-Scale Pore-Throat Heterogeneity of Tight Oil Sandstone Reservoirs and Its Influence on Fluid Occurrence State

Quantitatively characterizing the micro-scale heterogeneity of pore throats in tight sandstone reservoirs is key to accurately describing influence structures on fluid occurrence characteristics. In this study, taking Chang 6 Member Yanchang Formation Huaqing area Ordos Basin as an example, pore-throat and its state have been systematically studied using cast thin section, scanning electron microscope, X-ray diffraction, constant velocity mercury intrusion, nuclear magnetic resonance tests. The main types pores developed target layer were intergranular pores, followed by feldspar dissolution pores. radius distribution between 5.0 210 μm, with average value 50.27 μm. addition, combination best petrophysical properties are type, intergranular-dissolution dissolution-intergranular type; permeability porosity 0.62 mD, 0.40 0.44 12.0, 12.3, 12.3%, respectively. sandstones contain four typical T 2 relaxation time types. large-pore-fine-throat reservoir has properties. larger uniformity value, more uniform radius, greater permeability. Therefore, throat development controls seepage capacity reservoirs. movable saturation different obvious differences. saturations at 0.1 0.5 μm diameters macro-pore-fine-throat macro-pore-micro-throat both show inflection point, water higher a radius.