Study On Foam Combination Flooding After Polymer Drive

Polymer drive has received a good effect in Lamadian oilfield. However, there are fifty percent recoverable reserves remained underground after polymer drive. In order to improve recovery after polymer drive, foam combination flooding technology was studied. This paper investigated remaining oil distribution by using core sample analysis, static and dynamic data and numerical simulation. Foam system prescription was preliminarily determined by the screening of type and concentration of surfactant, the screening of concentration of alkaline, and the study of the effect of polymer system property and water quality on foam system property. The influence of polymer molecular weight, gas fluid ratio, injection rate, injection strategy on the effect of foam system displacing residual oil after polymer drive was studied and suitable foam system was developed through laboratory experiments. Injection parameters of the foam combination flooding after polymer drive were optimized based on the reservoir condition of pilot area, the actual injection ability during polymer drive and the injection history of foam flooding after water flooding in N-2-D area. After laboratory experiments seeing good results, filed pilot test on foam combination flooding was performed on a well in Lamadian oil field. After the injection of foam system, the injection pressure has risen, entry profile has been adjusted, the injection and production ability has dropped. Through this pilot test, it is realized that foam flooding has stronger injection ability in this kind of reservoir, and the surface injection technology for foam combination flooding was constructed. This study provides a good basis for the future large-scale pilot test of foam combination flooding.