缝洞型介质结构对非混相气驱油采收率的影响

为了研究缝洞型油藏的复杂缝洞介质结构对气驱油的影响,建立4类19个不同缝洞介质结构的数模模型,开展一系列非混相氮气驱油数值模拟研究。结果表明:洞相对于缝的位置越高,气驱油采收率越高;气驱油采收率随着洞密度和洞隙度的增加而增加,随驱替方向裂缝密度的增加而减小;洞的存在有利于提高气驱油采收率,并降低了缝洞介质结构对采收率的影响;气驱油的主要机制是由于密度差异形成的重力驱、体积膨胀补充地层弹性能和降低原油黏度改善流动能力,采收率主要受重力、洞密度、洞隙度、驱替方向裂缝密度等因素影响。

Influence of fractured vuggy structure on oil recovery efficiency during immiscible gas flooding

In order to study the influence of complex fractured vuggy structure on gas flooding, 19 models with 4 types of different fractured vuggy structures were established for a numerical simulation of immiscible nitrogen flooding. The results show that, the higher the position of the vugs above the fracture, the higher the oil recovery, and the oil recovery of gas flooding increases with the increase of vug density and porosity, but decreases with the increase of fracture density along the gas flowing direction. The existence of vugs can have a positive effect on oil recovery during gas flooding, which can overshadow the influence of the fractured vuggy structure. In general, the gas flooding mechanisms can be mainly due to gravity stabilized displacement, increasing formation energy, gas expansion and reducing of oil viscosity. Therefore, the oil recovery factor of gas flooding is mainly influenced by gravity, the density and porosity of vugs and the density of fractures along the gas flooding direction.