The Effect Of Surfactant System On Imbibition Bahavior

The characters and mechanisms of imbibition in porous media are fully discussed in this paper. After reviewing its scaling methods and measurements, the imbibition behaviors of surfactant are characterized in details, its application in naturally fractured low-permeability sands are deeply studied, and finally, a new method to enhance oil recovery is developed.Considering the directions of imbibed water and drained oil, two types are identified, namely cocurrent & countcurrent imbibition, and the regimes is due to the contribution of capillary and gravity. Based on the fluid flow mechanisms for oil-water-rock systems with different wettability states, scaling factor N_B^-1 for regimes is modified, making it more extensive and more perfect.In this paper, the ability of surfactant to lower IFT and to alter wettability situation and its efficiency are firstly evaluated, an optimal surfactant are selected out.Here, adhesion work factors (E), interfacial tension factor (E_?) and wettability factor (E_θ) were firstly introduced to characterize surfactant imbibition. Imbibition experiments shows that factors E, E(?), E_θ of the system with surfactant are drastically lower, making more oil displaced by imbibed water and the oil recovery higher.As to oil ganglion in throat, a nonzero capillary pressure potential and Marangoni effect by surfactant are driving forces for imbibition. Over resistance and adhesion, oil spontaneously migrates out, in contrast to water, countercurrent imbibition improved.In addition, according to the relative permeability experiments, wettability, alternated to more water-wet by surfactant, favors oil and water apt to flow, enlarging the range of the two phases co-flowing and enhancing oil recovery, help oil and water redistribute, lowing residual oil and more oil are movable and recoverable.Water-oil capillary pressure measurements for water and surfactant system with different wettability states shows that, by the chemical additive, water-wet situation obtained, imbibition in oil-wet situation occurs; centrifuge capillary pressure curves in...