Abstract:

Using the experimental technique of natural sandstone micromodel，an emmersion experiment of water sentivity is conducted for the Taizhou Formation reservoir sandstone in the Caoshe oilfield，Subei Basin. The experiment results show that the sandstone is moderate in water sentivity. In order to fully understand the impact of water-sensitive damage on water flood development，the water-drive-oil experiments of natural sandstone m icro-model are conducted，including two experimen types，i.e.a single model type and a combined model type，which simulate m icro-water-drive and macro-water-drive respectively and compare water-drive-oil variances before and after waterˉsensitive damage. The results show that the water-sensitive damage does not change the style of water drive oil and the configuration of residual oil. For the single model experiment，however，the bypassing phenomenon is strengthened on the whole and the oil displacement efficiency is lowered，mainly controlled by several factors such as water-injection pressure，water-injection location and micro heterogeneity. For the combined model experimen，the oil recovery ratio tends to decline totally，controlled by both the micro-heterogeneity and macro-heterogeneity. To avoid the impact of waterˉsensitive damage on water flood development，it is suggested that the injected water should be around11.99g/L in salinity.

Key words: oil displacement efficiency, water-sensitive damage, natural sandstone micro model, Taizhou Formation, Caoshe oilfield, Subei Basin