Study on Utilization Boundaries and Contributions of Pore Throats of Different Scales in Low-Permeability Reservoirs

Low-permeability sandstone oil reservoirs, as an important type of oil and gas resource, feature high reservoir density and low permeability. The utilization of pore throats of different scales during their development process is crucial for enhancing oil recovery. Based on nuclear magnetic resonance and CT scanning techniques, this paper systematically studies the utilization limits and energy contribution of pore larynx under different displacement methods. The results show that during the water injection development process, the main pore–throat radius used by water flooding is between 1 and 20 μm. Among them, the contribution of the small pore tends to stabilize after the pressure rises to a certain stage, the contribution of the medium pore increases with the rise in pressure, while the contribution of the large pore gradually decreases with the increase in pressure. After switching to CO2 gas flooding, the application range of the pore throat was further expanded to a smaller scale. The contribution of the small pore and the middle pore significantly increased in a specific pressure range, while the large pore made a greater contribution at a lower pressure. This paper has certain reference significance for the study of the limit and contribution of pore–throat exploitation in low-permeability sandstone oil reservoirs.