注气参数对注气驱非稳态驱替效果的影响

非均质油藏注入气与原油由于受粘性指进、重力和毛管力作用,表现出复杂的非稳态驱替特征.使用标定多相流态的无因次量组,采用组分数值模拟技术研究无因次注气参数(扩散数Nd、重力数Ng)对注气混相驱非稳态驱替效果的影响.结果表明,对于注气混相驱随着扩散数增大,溶剂与原油之间传质效果增强,与原油混相更加充分,驱油效率增大;而对于注气非混相和近混相驱,随着扩散数增大,驱油效率减小,采收率越小.注气速度引发的重力数越小,表现为驱替特征稳定程度由强变弱而最终影响驱油效率;而密度差异造成的重力数越小,驱替前缘越稳定驱油效率越高,控制合理的注气参数可以有效改善注气驱替效果,从而提高采收率.

Influence of Gas Injection Parameters on the Effect of Unstable-state Displacement by Gas Flooding

The features of reservoirs of unstable-state displacement was controlled by viscous fingering, gravity segregation and reservoir heterogeneity in gas displacements. The effect of dimensionless on injection gas parameters (dispersion number Nd,gravity number Ng) was studied to describe a multi-phase flow by using numerical simulation techniques. The study shows that the more dispersion number is, the mass transfer and the degree of miscibility between injection solvent and oil are enhanced, the displacement efficiency is higher for miscible gas flood. Whereas for immiscible and near-miscible gas flood, the more dispersion number is, the displacement efficiency is less and the oil recovery is lower. The more gravity number induced by the injection parameters is, the flow regime changes from (he pattern of gravity control to the viscous finger control, the degree of stability has some impact on displacement efficiency. The less gravity number induced by the differential density is. More stable displacement front is and the higher efficiency is. Reasonable control of gas injection parameters can be effective for improving the effect of gas injection displacement and enhancing recovery.