Distribution of remaining oil by water flooding in heterogeneous reservoirs and indoor simulation study for its potential tapping

In order to tap the potentiality of the remaining oil from water flooded layer of the long-term water flooding oil fields, a visualized heterogeneous model was developed through analyses of the pore structure and the size of pore throats of the reservoirs, which was used to carry out indoor observation of the formation process of water flooding remaining oil by way of video and analysis was conducted of its distribution characteristics and way of thinking of potential tapping techniques. Based on the material properties of elastic particles in throat structure, the screening principle for the diameter of this elastic particle which was in match with reservoir throat was presented. And through test of profile control of particles after water flooding in heterogeneous cores, evaluation was made on the dynamic plugging capacity and profile control effectiveness of this elastic particle. The results show that heterogeneity occurs commonly in oilfield reservoirs, which affects the distribution of water flooding remaining oil; the remaining oil in flooded layers is mainly heterogeneous remaining oil, mostly found in local low-permeability zones of the layers and distributed dispersedly, so its potential tapping will be mainly by improving the microscopic sweep efficiency; the plugging strength of elastic particles on throat increases first and then keeps constant with the enlarging of elastic particle diameter-when the ratio of particle diameter with throat diameter is over 3, the particles will be broken in throat structure; when plugging the water channel in water flooded layer and tapping the remaining oil, the elastic particle works effectively whose diameter is three times of the size of throat.