Abstract: A three-dimensional network model for oil-water two-phase flow was proposed. The influences of pore radius, pore-throat ratio, shaping factor and coordination number on distribution of remaining oil in the oil-wet, water-wet and middle-wet reservoirs were investigated by means of microscopic simulation. The results show that the probability for generating remaining oil in oil-wet or middle-wet reservoirs would be larger as the pore radius and coordination number get smaller or the shaping factor becomes larger. The same was for the water-wet reservoirs as the pore radius becomes larger or the shaping factor becomes smaller. The pores with suitable coordination number will lead to high sweep efficiency. Also remaining oil can be generated easily in the pores with a large or small coordination number. In general, the probability for generating remaining oil in water-wet,oil-wet reservoirs and middle-wet reservoirs will become larger as the pore-throat ratio increases.