Abstract: Sangonghe reservoir in Cainan oilfield is characterized by active edge and bottom water, abundant natural energy, good connectivity, high permeability, low oil-water-viscosity ratio and high pressure conductivity coefficient, and quickly-replenished edge and bottom water, suitable for a long-term development with natural energy.According to characteristics of different blocks, this paper discussed how to determine reasonable water injection timing, position and oil recovery rate in order to maximize the utilization of its natural energy. Sangonghe reservoir was developed with oil recovery rate of 2.9 %~ 3.4 %for more than five years, kept stable production of oilfield in low-moderate water cut stage and obtained higher oil recovery and better economic benefit.

Key words: Junggar basin, Cainan oilfield, Sangonghe formation, Edge water, Bottom water drive, Reservoir, Natural energy, Development