The LaSaXing Oilfield has entered the ultra-high water cut stage, and the original evaluation indexes of water flooding development effect cannot reflect development status of the oilfield. In order to correctly evaluate the water flooding development effect of the oilfield at ultra-high water cut stage, the indexes were extensively selected in terms of geological conditions, development technologies, production management, and economic benefits, and they were initially screened by observation principle, the Delphi method, and theoretical analysis. Then, the evaluation indexes were quantitatively selected by Pearson correlation analysis and combination of gray clustering-rough set to establish the index system evaluating water flooding development effect of oilfield at ultra-high water cut stage. The practice showed that the index system evaluating the development effect, which was scientific, objective, and strongly applicable, had great significance for comprehensive evaluation of the water flooding development effect of oilfield at ultra-high water cut stage, analysis of development potential, and formulation of development adjustment plan.
