Investigation of the Dynamic Capillary Pressure During Displacement Process in Fractured Tight Sandstone Reservoirs

Dynamic capillary pressure affects the non-equilibrium multiphase flow behavior in porous media. Fractures has been shown to influence the dynamic capillary pressure in tight rocks, but the role of fractures on the dynamic capillary pressure during the production process in tight sandstone reservoirs remains uncovered. This work examines and simulates the dynamic displacement process in fractured tight sandstone oil reservoirs. The dynamic capillary pressure, the dynamic coefficient and the dynamic relative permeability are measured through specially designed experiments to show the effects of fractures on the dynamic fluid flow process. The experimental data are then used to simulate the reservoirs production process applying the CMG. Results have shown that the dynamic capillary pressures of the fractured samples are 5-15% higher than the intact ones. The dynamic effect is weakened by the fractures indicated by the lower values of dynamic capillarity coefficient in the fractured core samples. Dynamic relative permeability curves are higher than the steady ones at low water saturation, and lower than the steady ones at high water saturation. The production rate of the reservoir is overestimated if dynamic effect is ignored in fractured tight sandstone reservoirs, and the production well will be predicted to breakthrough earlier, with a higher breakthrough water flow. This paper helps to understand the multiphase flow behavior and simulate the oil recovery process in fractured tight sandstone reservoirs.