Abstract: The microscopic feature and the expansion multiplying factor of new pore-throat scale microsphere As Profile Control Agent are measured using XL30 Scanning Electron Microscope and new expansion multiplying factor evaluation method. The effects of temperature, salinity and swelling time on expansion performance of microsphere are analyzed. The results show that the expansion multiplying factor of microspher's grain diameter gradually increases with the temperature and the swelling time increasing, decreases with the salinity increasing, and ultimately being stable. In Gasi reservoir, this expansion multiplying factor is 3.93 after the microsphere expanded for 15 days under the circumstances of formation water (17 4501 mg/L) and temperature (126℃), showing good temperature resistance, salinity resistance and stability. The performance of migration and plugging of the microsphere As Profile Control Agent is studied by the long core test, showing that it has good injectivity and plugging capacity. The core displacement test indicates that the EOR given by such a new microsphere approach is up to 11.80%.

Key words: profile control agent, microsphere, temperature, salinity, performance, EOR