Abstract: Based on the input-output balance theory, a method for evStimating economic limit water cut is presented through analyses of components and changes of production cost of waterflooding conglomerate reservoirs in Karamay oilfield. Results of its application in typical reservoirs showed that economic limit water cut is 92% for the 1st-class reservoirs, and 90% for the 2nd- and 3rd-class reservoirs. Ultra-high water cut bound for cyclic low-efficiency to inefficient oilfield operation is 93.5%.

Key words: Conglomerate reservoir, Economic evolution, Water cut, Output per well, Oil production cost