Characteristics of viscosity-reducer foam flooding in deep low-permeability heavy oil reservoirs
Viscosity-reducer foam flooding combines the advantages of emulsification of viscosity-reducers and selective blocking of foam to further enhance oil recovery in deep low-permeability heavy oil reservoirs during the later development stages.The suit-able concentration of viscosity-reducing foam agents were selected according to the viscosity-reducing effect,foaming performance and foam stability of the agents by laboratory experiments.Meanwhile,the characteristics and recovery effects of viscosity-reducer foam flooding under different displacement modes were compared by single-core displacement experiments,and the diverting ca-pacity of viscosity-reducing foam at various permeability ratios were investigated by parallel core experiments,and thus the en-hanced oil recovery(EOR)mechanisms of viscosity-reducer foam flooding ware defined.The results demonstrate that the viscosity-reducing agents facilitate the emulsification and viscosity reduction of heavy oil,while the foams block large pore throat and inhibit N2 channeling during viscosity-reducer foam flooding.Combination of the both can improve the sweep coefficient and displacement efficiency,increase displacement pressure differential,and lower the water cut.Furthermore,the viscosity-reducer foam flooding can enhance the oil recovery by an additional 13%based on the viscosity-reducer flooding.In heterogeneous conditions,viscosity-reducer foam flooding decreases the high-permeability core channeling to direct the flow towards low-permeability cores,thereby exerting an emulsification and viscosity-reducing effect.Finally,this expands the swept volume and simultaneously enhances the displacement efficiency.While the viscosity-reduce foam flooding significantly enhance the oil recovery of deep low-permeability heavy oil reservoirs by optimizing the oil flow distribution,enhancing emulsification,and reducing heavy oil viscosity,thus pro-viding an effective strategy for efficient development of deep heavy oil reservoirs.
deep heavy oil reservoirviscosity-reducer floodingfoam floodingviscosity-reducer foam floodingEOR
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