| 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 Ι and water saturation Sw 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-Sw 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. ② Under 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 λD (length of electrical double layer) is controlled by electrolyte solution concentration and valence of counter ion ③ Break-through of injected water or high-pressure hot steam in high permeable sections were the reasons of resistivity change. Electrical anisotropy caused by different ratio of harvesting among layers in heterogeneity reservoir made the apparent resistivity of the survey zone decrease obviously, though the amount of residual oil was still large enough. ④ The main factors causing electrokinetic phenomenon are abnormal pressure and salinity decrease and multiphase flow in oil field development, and the positive and negative changes of self-potential were the expressions of the streaming potential in waterflooded zone. ⑤ Velocity of elastic wave was affected by reservoir's temperature and pressure changes in oilfield development. Velocity was decreased linearly with temperature raising and decreased logarithmically with pressure decreasing. ⑥ Wettability of rock affected displacement efficiency and water-flooding oil recovery. Residual saturation was low, and oil recovery was high of water-wet rock; water breakthrough came early, and water-cut period was long of oil-wet rock. (3) On the basis of petrophysical experiments and theoretical study, water-flooded zone's log interpretation methods were improved, and the infilled and adjusted wells in development oilfield were evaluated. For example adjusted parameters m, n, B and Rw to perfect original saturation medel, Using other methods to evaluate saturation of water-flooded zone such as ratio of resistivity.
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