Abstract: Igneous reservoirs are complex and exhibit a wide variety.And accordingly, water flood responses of the individual lithofaies zones are different, which renders difficulties for harnessing in later-phase development. It is proposed in this paper that water-cut curves of oil wells can be used to analyze the waterflood character so as to increase water drive efficiency. The method has been applied to the Abei andesite oil reservoir, with four types of water encroachment recognized. Based on such analyses, adjustments were made to the waterflood performance and markedly increased water drive efficiency was obtained.

Key words: Igneous reservoir, water drive efficiency, water-cut curve, adjustment