Abstract: The Karamay-Baikouquan oilfields were developed with water injection. The distribution and controlling factors of the surplus oil in the water injecting developed resetvoirs were analysed through the behaviour analysis. sealed coring and numeric simulation. Tt was considered that the depositionai environment was the major factor in controlling the surplus oil distribution of the oil reservoirs.

Key words: Karamay oilfield, Baikouquan oilfield, Conglomerate reservoir, Surplus oil, Sedi-mentary facies, Sealed coring, Numeric simulation