Based on the research of earlier stage, a detailed investigation was conducted over the synergistic oil displacement mechanism and various physico-chemical phenomena. Especially, the new physico-chemical phenomena of combination flooding recognized in recent years have been further studied and described in detail. Both the mathematical model and the software ASP used for combination flooding established before have been systematically improved or modified. For the first time, such factors as change of interface tension caused by the multi-extraction of alkali, change of solution viscosity due to the further polymer hydrolysis after adding alkali, and change of combination system interface tension by adding polymer have been incorporated into the mathematical model. Thus the model is a more consummate, more exquisitely described and more realistic one. Based on the detailed analysis of various vital influential factors, the improved simulator ASP is used to conduct a great number of series of numerical simulation research. A systematic analysis is firstly carried out upon the sensitivity of various influential factors (including geological factors, physicochemical phenomena, starting conditions and operational parameters) of combination flooding and its effects, from which important recognitions and conclusions in regular have been drawn. A further understanding has been achieved on combination flooding process that is important for further researches and oilfield applications.
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