Abstract: In this paper,the mechanism of cychc water flooding has been studied by NMRI tech-niques.Based on the action of pressure fluctuation and capillary force in the sample,cyclicvvater flooding can improve oil recovery.Capillary force introduces imbibition in water-wet-ted sample.Periodical pressure fluctuation between high and low permeability area leads tothe change of oil saturation in both areas.The pressure variation(rising and dropping downperiodically) in high permeability area is more prominent than in low permeability area.Notall of the water percolated into low permeability area can flow back into high permeabilityarea.So oil saturation in high permeability stratum gets rising as the pressure drops down.The greater of pressure fluctuation,the greater effect of cyclic water flooding.This methodis effective in both of oil and water wetted reservoirs.

Key words: oil displacement mechanism, cyclic water flooding, nuclear magnetic, resonance, image techniques

摘要： 用核磁共振成像技术研究了周期注水驱油机理.压力扰动弹性效应和高低渗透区之间的油水交渗效应是周期注水的主要机理,对不同地层可实施不同方式的周期注水,它对水湿地层和油湿地层都是有效的.

关键词: 驱油机理, 周期注水, 核磁共振, 成像技术