Residual oil start-up mechanism of polymer/surface dual flooding after polymer flooding in medium-high permeability reservoir

The remaining oil distribution and displacement mechanism of poly/surface dual flooding stage in medium high permeability reservoir are not clear. In this paper, the conditions Gangxi Area 3 Dagang Oilfield were taken as research object. Based on nuclear magnetic resonance large model physical simulation experiment, characterization micro macro residual start-up enhanced recovery experiment carried out respectively after polymer binary flooding. experimental results suggest that polymer-surfactant could increase efficiency by 12-29% flooding, contribution porous to degree is order pore, small pore. When surfactant concentration higher than 0.25%, tends be stable, further enhancing requires expansion sweep volume. Physical experiments show layer has highest chemical stage, mainly based synergistic effect expanding volume improving efficiency. low next, expand lowest degree, improve