关键词: 聚合物驱, 吸水剖面, 返转时机, 返转机理, 阻力系数, 模拟实验

Abstract:

The section inversion rules and inversion mechanism during polymer flooding were studied by using physical simulation experiment of indoor parallel core and the basic principles of seepage mechanics.The study result showed that reservoir heterogeneity resulted in the section inversion.With the increase of permeability ratio and advancement of inversion opportunity,the cumulative imbibition rate of low-permeability layer decreases.Under the condition of fixed permeability ratio,the cumulative imbibition rate of low-permeability layer and the sweep efficiency of polymer flooding decrease with the increase of molecular weight and concentration of polymer and the advancement of inversion opportunity.The section inversion lies on the different change laws of dynamic resistance coefficient of polymer solution in the high and low permeability layers.In the high permeability layer,the resistance coefficient rises in the logarithm form.While in the low permeability layer,the resistance coefficient rises in the index form.In the high permeability layer,the changing rate of resistance coefficient decreases constantly,while in the low permeability layer,the changing rate of resistance coefficient continuously increases.In the primary stage of polymer flooding,the changing rate of resistance coefficient in the high permeability layer is bigger than that in the low permeability layer.When those are equal,the water injection profile begins to invert.

Key words: polymer flooding, water injection profile, inversion opportunity, inversion mechanism, resistance coefficient, simulation test