Study on Water-Oil Flow Characteristics in Porous Media

During recent five years, the percentage of low-permeability reservoirs in newly increased proven reserves has reached 50~60%. And in the remaining reserves low-permeability reservoirs account for 76.5%. But in normal situations, the average recovery efficiency of water- injected reservoirs is only 33%. Study on how to reduce the amount of residual oil and to enhance oil recovery efficiency is of great significance.In this paper, experimental and theoretical analysis on water-oil flow characteristics in low-permeability porous media were introduced. Main conclusions are as follows. Critical volumes of injected water for high-permeability, low-permeability and heterogeneous porous media were found in the experimentals, which were 1.5PV, 2PV and 3.5~4PV respectively; Concept of "utilization ratio of the differential pressure" was first put forward, which could be used to analyze and evaluate the utilization of displacement pressure.