凝析气藏气液两相渗流的高速流动效应研究

RESEARCH ON HIGH-VELOCITY EFFECT ON GAS-LIQUID TWO-PHASE FLOW CHARACTERISTIC OF CONDENSATE GAS RESERVOIRS

为了研究高速流动效应对凝析气藏渗流特征的影响,在凝析气藏不稳定渗流数学模型中引入非达西效应和毛细管数效应对相对渗透率的修正模型,并进行数值求解。研究表明,在较低的凝析油饱和度时,毛细管数效应起主要作用,对凝析油产生速度剥离效应,提高气相相对渗透率,而在较高的凝析油饱和度时,非达西效应对气相相对渗透率的负作用更加明显;油相相对渗透率对非达西效应不敏感,但随毛细管数增加而增加。考虑高速流动效应的储层径向上凝析油饱和度明显低于不考虑高速流动效应的情况,随日产气量的增加,近井带的毛细管数效应逐渐增强,远离近井带,非达西效应逐渐超过毛细管数效应,使得最大反凝析液饱和度区不断沿径向向外推进。

In order to study high-velocity effect on gas-liquid two-phase flowing characteristic of condensate gas reservoirs, a modified model considering non-Darcy effect and capillary number effect was introduced into transient flowing model of gas condensate reservoirs which was solved by Newton interactive method. Capillary number effect is dominant in low condensate saturation and can strip liquid drop-out, which can improve relative permeability of gas phase. While in higher condensate saturation, non-Darcy effect does greater harm to relative permeability of gas phase. Relative permeability of oil phase increases with the capillary number but is insensitive to non-Darcy effect. Condensate saturation along wellbore radial considering high-velocity effect is much lower than that without considering high-velocity effect. With increase of gas flow rate, capillary number effect is gradually becoming stronger near wellbore. Far from nearby wellbore, non-Darcy effect exceeds capillary number effect. So the maximum condensate saturation region is moving outward from wellbore.