The influence of pore throat structure on fluid displacement in tight oil reservoir

Abstract Based on core imbibition experiments combined with nuclear magnetic resonance technology, this study identifies the dominant governing forces for different pore throat types and quantitatively characterizes the contribution of pore throats at various levels to imbibition-driven oil production. The results show that: Higher permeability correlates with greater fluid displacement rates. In reservoirs with high permeability, gravity dominates the imbibition process, with macropore recovery accounting for 96.27% of total recovery. In reservoirs with lower permeability, both gravitational and capillary imbibition forces are prominent. Fluid displacement primarily occurs during the early imbibition phase, with relatively weaker displacement in the later phase. Macropore recovery accounts for 86.36% of total recovery, while mesopores contribute a minor portion of imbibition recovery. Pinholes and micropores also make negligible contributions. Whether driven by gravitational or capillary forces, macropores and mesopores are the primary contributors to imbibition recovery rates, indicating that oil content and connectivity are critical factors influencing imbibition recovery efficiency. This research provides valuable guidance for enhancing recovery rates through imbibition enhancement in tight sandstones. Clinical Trial Registry :NOT APPLICABLE