EFFECT OF PARALLEL MICRO-FRACTURES ON FLOODING BASED ON PORE-FRACTURE NETWORK MODEL

It is of great importance to understand the micro-seepage mechanism of water flooding in dual pore-fracture media, for the improvement of the recovery efficiency. The existence of micro-fractures can on the one hand increase the absolute permeability, on the other hand change the local fluid pressure distribution and flow in the porous media. The fracture flow prevails, the surrounding oil cannot be displaced, reducing the displacement efficiency. In this paper, a pore-fracture network model is used in the analysis, two parallel micro-fractures with equal length are set at the inlet. The effects of the relative interval (micro-fracture gap length/throat length) and the relative length (micro-fracture length/throat length) of the micro-fractures on micro-seepage are investigated. The results show that with the increase in relative length of micro-fractures, the displacement efficiency decreases, while the water saturation at the co-permeable zone and at the intersection of the relative permeability curve increase. With the increase of the relative interval between the two fractures, the pressure of the surrounding pores is approximately equivalent, and the oil displacement will not occur due to the capillary pressure, leading to water channeling and the decrease of the oil recovery.