Study on Polymer Surface Binary Flooding System in Changqing Low Permeability Reservoir

Abstract

AbstractChangqing oilfield Jurassic reservoirs are typical low permeability reservoirs. After years of water flooding development, most of the reservoirs have entered the the medium and high water cut stage, The comprehensive water cut has reached more than 66%, but the recovery degree is less than 30%. Compared with other CNPC binary flooding test areas, polysurface binary flooding in the Jurassic low permeability reservoir in Changqing has low permeability, strong heterogeneity, and higher salinity of formation water and injected water. Therefore, it is necessary to carry out injection experiments of polymers with different molecular weights to establish injection charts suitable for Changqing oilfield. According to the characteristics of Changqing low permeability reservoir, the low molecular weight salt-resistant hydrophobic association polymer suitable for reservoir was optimized, and the surfactant with good adaptability to reservoir was developed. The experimental results show that the system has a synergistic viscosifying effect, good shear resistance and good thermal stability. Compared with water flooding, binary flooding can improve oil displacement efficiency by 20.5% and achieve better field application effect.KeywordsLow permeability reservoirsPolymer injectabilitySurfactantThe binary systemImprove oil displacement efficiency