Investigation of the dynamic capillary pressure during displacement process in fractured tight rocks

Abstract

Abstract This work investigates the dynamic capillary pressure during the displacement process in fractured tight rocks, through specially designed experiments on fractured and intact core samples. The dynamic capillarity coefficient of matrix and the multiphase flow behaviors are also obtained. Results have shown that the dynamic capillary pressure of the matrix becomes around 5–20% higher after the fracturing treatment. The lower and less variable values of dynamic capillarity coefficient of matrix illustrate a weakened dynamic effect and a more uniform displacement front. Moreover, time derivative of water saturation is increased significantly with fractures. Finally, oil relative permeability after fracturing is lower than its value of the intact core at high water saturations. A dynamic capillarity coefficient model for matrix, which includes the influence of fractures, is derived and verified with the average R 2 more than 0.95. This wok helps to understand and predict multiphase flow in fractured tight porous media.