Application of polymer microspheres profile-controlling technology in Changqing oilfield

In order to decrease the horizontal and vertical heterogeneity and improve the sweep efficiency in the water-flooding exploration in Changqing oilfield, the laboratory and field tests were conducted using a kind of synthetic polymer microspheres ( PM ). When the PM were put into the simulated formation water with TDS of 10 × 104mg/L at constant temperature of 55°C , the mean particle size of the PM would increased from 305.7 nm to 4 jxm within 5 days, and the morphology of the PM was spherelike after soaked for 20 days by the measurement of TEM. The plugging experiment was conducted by the sandpack test with mean permerbility of 425 × 10-3 μ2. It was indicated that the plugging efficiency was 93. 0% and residual resistance factor was 15. 5. Field tests were carried out in two stages on 6 injectors, with the result of increased injection pressure. For wells with high water cut, there was decline with the production of liquid and water, while for wells with poor oil-production profile, the production of liquid and oil increased.