Kinematical description of the spontaneous imbibition processes

A set of experiments of spontaneous imbibition for water displacing oil or a mixture of water and glycerine displacing oil, on flat and rectangular Hele-Shaw cells, is reported. Visualization of the imbibition process allowed the knowledge of the evolution of three basic kinematical variables: the active oil area, the interfacial length and the mean velocity of displacement. A derived kinematical variable, the active area equivalent length, is shown to be well suited for the kinematical description of spontaneous imbibition processes, since its normalized values become lumped to a narrow experimental band when two time scales are defined and used, looking for a self-similar behavior. The dimensionless active area equivalent length is found to be lumped to a narrow time gap, for a potential function with two time scales. This function is found to be appropriate for further description by a fractal approach. Key–Words: Spontaneous imbibition, Hele-Shaw cells, Oil recovery, Interfacial tension, Sweep efficiency.