Late Steam Stimulation Of Heavy Oil Residual Oil Distribution In

For the problems of reservoir properties and oil/water distribution evaluation in the development of high water-cut stage, based on systematic summarization of reservoir characteristics in the process of water-flooding and steam-injecting oilfield development, log responses mechanism, relationship between log information and development reservoir properties were discussed in detail through theory analysis and petrophysical experiments simulating the process of oilfield development in order to improve interpretation method in high water cut stage of oilfield development. (1) Environment of reservoir, properties of pay zones and distribution characteristics of pore fluids (oil-water) were researched on the basis of comprehensive analysis on geology characteristics of continental heterogeneity reservoir, oilfield development procedure and production performance, reservoir model of late period of development was built up, in which reservoir's temperature, pressure, oil and water property, depositional feature, homogeneity, and rock wettability were considered. (2) Rock petrophysical characteristics in high water cut stage were studied by related theories and water-drive-oil experiment simulating oilfield development process. Relationships among environment of reservoir, water-flooded characteristics of reservoir and log responses were built. ①Relationships between resistivity index Ιand water saturation S_w obtained from drainage and imbibition are different owing to the different process of oil-drive-water and water-drive-oil. Experiment results simulating oilfield development indicated that resistivity index and water saturation showed a non-liner pattern in dual-logarithm coordinate in water-drive-oil process, but obvious two section related with high and low zones of water saturation. Characteristics of Ι-S_w relationship under water-drive-oil process showed that resistivity curve can not reflect water saturation exactly in high water cut stage of oilfield development. Therefore, it is unsuitable to evaluate development reservoir with high water cut using model from water-drive-oil process. ②Under lower salinity condition of less than 20000ppm, parameters m, n and B of saturation equations increase with solution concentration; but when the concentration is high enough, m, n and B maintain steady, do not change obviously with salinity. It is because that λ_D (length of electrical double layer) is controlled by electrolyte solution concentration and valence of counter ion...