Abstract: Aiming at the highly discrete and locally enriched distribution contradictions of oil and water in mid-deep high-water-cut reservoirs in the Jidong Oilfield,micron CT experiments and displacement experiments were integrated to systematically reveal the dynamic evolution laws and control mechanisms of residual oil at the pore scale.The results show that the relative sorting coefficient of pore radius in high-permeability and low-permeability reservoirs is significantly higher than that in medium-permeability reservoirs,resiindicating a "polarized" distribution characteristic of reservoir heterogeneity;residual oil can be divided into five forms:network,porous,narrow-throat,isolated droplet,and film-like;in the original reservoir,the proportion of network residual oil is positively correlated with reservoir permeability.During the water flooding stage,the oil displacement efficiency is positively correlated with the contribution rate of mega-pores and permeability.The increase in recovery factor by binary combination flooding shows a bimodal characteristic,i.e.,the increase in high-permadbility and low-permeability groups is significantly higher than that in the medium-permeability group,and it is strongly positively correlated with the pore radius sorting coefficient.Based on this,a staged differentiated development strategy is proposed:"staged development" in the water flooding stage,prioritizing the development of medium- and high-permeability layers,and "U-shaped" regulation in the chemical flooding stage,implementing selective plugging in medium-permeability reservoirs and collaborative development of binary combination flooding in high-permeability and low-permeability reservoirs.The research results provide theoretical support and engineering practice guidance for precise potential tapping of remaining oil.

Key words: micron CT, displacement experiment, pore structure, remaining oil, water flooding, polymer surfactant, binary combination flooding