Studies On The Mechanism Of ASP And The Injection Optimization Of ASP Flooding

On the basis of the information analysis of chemical flooding, the ultra-low interfacial tension, emulsion, mobility ratio, wettability of reservoir in the ASP flooding were investigated by the core flooding tests with micro-model, parallel connection physical model. Based on the experiments the injection mode of ASP flooding was optimized, and the results should be constructive for the popularization of ASP flooding. The main conclusions are as follow:1. The ASP flooding can not only increases the oil displacement efficiency, but also improves the sweep coefficient. The mechanisms of the ASP flooding are: (1) The ultra-low interfacial tension between oil and water can increase the capillary number and decrease the oil saturation of remaining oil, so it would improve the oil displacement efficiency; (2) The addition of the polymer can increase the viscosity of the system and decrease the mobility ratio, so it can improve the flow field, reduce the finger advace and increase the sweep coefficient; (3) The ASP system and crude oil can form the emulsion, the oil drop will aggregate continually and form the oil wall, then more and more residual oil will be emulsified and displaced; (4) The addition of surfactant and alkali changes the wettability of reservoir.2. The parallel connection core tests shows that the alternately injection of P/ASP can increase the sweep efficiency obviously compared with the normal infection mode of ASP flooding, the fruid injection of the low permeability layer improve availably, and the oil recovery can be increased about 5%. In the core test, the cost of the ASP flooding can be reduced about 20% with the alternately injection mode and combined with the reduction of the alkaline and surfactant.