Oil/water Inversion and Its Genetic Mechanism in the Higher Portions of the Single Sandstone Body

Key words: 
• low permeability reservoirs /
• oil/water distribution /
• lithologic oil reservoirs /
• genetic mechanism /
• heterogeneity of reservoir

Abstract: Complexand levityof geological conditions for forming oil reservoirs result inthe complex nd levityof oil/water distribution, especially, in low permeability reservoirs. There have one kind of oil/water inversion in fault trap and lithologic oil reservoirs, that is, from the high portions of the single sandstone body to the low portions, they are water layer, waterbearing layer, oilwater layer, oil layer, oilwater layer, waterbearing layer, and water layer. According to analysis on the controlling factors of the oil/water inverted distribution in low permeability reservoirs, two kinds of genesis mechanisms were discussed. The results indicate hat there have two status. First, in fault rap, the history diversity f the fault sealing is the key reason for the oil/water inverted distribution and physical properties of reservoir and permeability difference are the second reason. Second, in upward wedge out sandstone,physical properties of reservoir and its levity, especially, the heterogeneity of layer, are the key reasons for the oil/water inverted distribution. Meanwhile,The results indicate hat they include the lowresistivity pay zone in the oil/water inversion system.