Research On Emulsification Characteristic Of ASP System And Its Effect On Oil Displacement Effect

Our ASP flooding technical started fairly late, but developed rapidly. Field application of Daqing indicated that ASP flooding could enhance oil recovery over 20%. With the development of ASP flooding field test, emulsification characteristic of ASP system and its effect on oil displacement effect become the focus question that people pay attention to gradually.In this paper, the main study on ASP complex system in lab is as follows: methods of judgement of type of emulsions and preparation for emulsions were determined. Emulsions of Daqing crude oil with different chemical agents system were prepared, and type, particle size, and stability of emulsions were analyzed, the influencing laws of different factors on type and stability of emulsions were studied. Some oil displacement experiments were done with different permeability long core physical models, and done some research on emulsification laws of oil with complex system at medium and high watercut stages in the process of ASP flooding. In the homogeneous cores of different permeability and in the heterogeneous cores of different CVs, the effect of crude oil emulsification on oil displacement effect was studied.The results show that: the higher stirring intensity is, the more stable emulsion is, but the stability is degraded on exceeding the critical shear strength. With the prolong of stirring time, the emulsions are more stable, but over a certain time the stability is degraded. The type of emulsions is close association with water-cut, the influence on the transformation of emulsion arranged by the orders from major to minor is water-cut, surfactant, alkali, polymer. With the increasing of chemical agents concentration, the emulsions of oil with ASP are more stable, three agents are interrelated and interaction. Surfactants, polymer and ASP is favorable for the formation of the O/W emulsion, alkali is favorable for the formation of the W/O emulsion. In low-permeability cores, emulsification of ASP flooding appears early, the emulsion is dark in color, and the degree of emulsification is greater. In high-permeability cores, the emulsion appears later, the color is lighter, and the degree of emulsification is weak. In the condition of middle water-cut, the emulsion appeared early and the degree of emulsification is greater. In the condition of high water-cut, the emulsion appears later and the degree of emulsification is weak. Emulsion system have better oil displacement effect and can increase oil recovery by 5%～10% compared with the system not to emulsify.