Study On Scheme Of The Unstable Waterflooding In The Low Permeability Reservoir

Daluhu oilfield, a medium-sized ultra-low permeability oil field is discovered and putted into production in 1990's. It's necessary to adjust the water flooding method due to serious formation anisotropy and complex oil-water relationship, the efficiency of water flooding gradually drops down. Based on documentation study, theoretical research and numerical reservoir simulation software application, the macro and microcosmic mechanism of elastic and capillary force during the unstable water flooding in F29 block of Daluhu oilfield to improve the production ability of low-permeability reservoirs were studied, and the effect of formation Anisotropy, oil-water viscosity ratio, formation wettability and formation elastic compression factor were analyzed. According to the geological model of F29 block, the producting indicators were matched and pridication plans were designed using the numerical reservoir simulation software. The plans were optimized on the effect of all parameters together and the development of F29 block. After 3 unstable water-flooding injection cycles, average daily production of oil increased from 47.8t/d to 63.78t/d and the water-cut increased slightly from 73.52% to 74.24%, and formation pressure also was buildup slowly and the decline rate decreased from 2.0MPa/a to 0.52MPa/a. The study can improve the development effect of Daluhu oilfield and similar fields.