Abstract: Based on formation water analysis data from Huanghenan area in Dongpu sag, the salinity variation and origin of the formation water are discussed, and the relation of the formation water salinity to sedimentary environment and oil-gas distribution is expounded. It is pointed out that the area or zone with high salinity possesses high abundance of organic matter and enough supply of oil source. So it is favorable area for oil-gas accumulation. TI1e authors proposed viewpoint that pools with both source and reservoir could be found in the zone with high formation water salinity. The rolling exploration/development practice in recent two years has gained outstanding effectiveness with incremental the cumulative proved reserves of over 1000x104^t.

Key words: Dongpn sag, Huanghenan area, formation water, salinity, oil-gas distribution