Effects of Chemical Additives on Dynamic Capillary Pressure during Waterflooding in Low Permeability Reservoirs

Abstract

It is suggested that the capillary pressure–fluid saturation relationship should be determined as a function of a dynamic coefficient (τ) and the time derivative of fluid saturation (∂Sw/∂t), indicating a dynamic capillary pressure in most cases, which will increase the flowing resistance and injection pressure for oil-wet reservoirs, especially in low permeability formations. To decrease the injection pressure and improve injection, various chemical additives such as surfactants and fluorides have been widely used in the waterflooding process in low permeability reservoirs. Effects and mechanisms of these chemical additives are yet not well-known. In this paper, a series of specially designed waterflooding experiments were conducted to investigate the effects and mechanisms of surfactant additives on the dynamic capillary pressure–fluid saturation relationship in low permeability reservoirs. In the experiment, capillary pressure–fluid saturation relationships in three low permeability core samples were e...