Research Article

Research on Effectiveness and Application of Fixed-Plane Perforation Fracturing Technology in Ultra-Low-Permeability Reservoir

Table 3

Classification standard of a single sand body oil reserves [8].

ClassificationDisplacement characteristicsPorosity (%)Permeability (mD)Microscopic pore throat radius (μm)Natural gamma (API)

Class IGood physical properties, easy to form (fingering) watered-out channels, early watered-out, good displacement effect, and high oil recovery≥14≥0.8≥0.250.3-0.5
Class IIThe water flooding front advancing is slow, physical properties are relatively poor, swept efficiency is low and widely distributed, and there is high shale content≥10-14≥0.2-0.8≥0.1~0.251.5-0.3
Class IIIBelonging to the unconventional tight formation, which cannot be swept and used temporarily; the reserves can be calculated, unless developed by gas flooding in the future<10<0.2<0.10-1.5