深层稠油油藏降黏泡沫驱驱油特征及机理研究

Characteristics of viscosity-reducer foam flooding in deep low permeability heavy oil reservoirs

降黏泡沫驱结合了降黏剂乳化降黏和泡沫选择性封堵的优势,可进一步提高开发后期深层稠油油藏的采收率。通过室内实验,根据降黏泡沫剂的降黏效果、起泡性能、泡沫稳定性,优选出合适的降黏泡沫剂浓度;通过单岩心驱替实验对比不同驱替方式下降黏泡沫驱驱油特征以及开采效果,通过并联岩心实验研究不同渗透率级差下降黏泡沫的分流能力,明确降黏泡沫驱提高采收率机理。结果表明:降黏泡沫驱过程中,降黏剂可以促进稠油乳化降黏,泡沫可以有效封堵大孔喉,同时抑制氮气窜流。二者结合有效提高波及系数和洗油效率,提高驱替压差,降低含水率。降黏泡沫驱可以在降黏泡沫剂驱的基础上进一步提高13%的采收率。非均质条件下,降黏泡沫驱可以有效降低高渗透岩心窜流,迫使流体转向进入低渗透岩心发挥乳化降黏作用,扩大波及范围的同时提高了洗油效率。降黏泡沫驱技术能显著提高深层低渗透稠油油藏的采收率,其优化了油流分布,增强乳化与减少稠油黏度,为深层稠油高效开发提供了有效策略。

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.