An accurate evaluation of injectivity is essential to the economics of any chemical EOR process. Most commercial simulators enable non-Newtonian behaviour modelling but it is often overlooked due to inadequate grid resolution. Indeed, in cases where shear-thinning fluids are injected in a reservoir, shear rates and viscosities in the vicinity of the wellbore can be poorly estimated if the spatial resolution of the well grid-blocks is too coarse. This results in biases in injectivity and economics which we discuss here in the context of foam-based displacements.

We first demonstrate that a poor evaluation of near-wellbore velocity leads to erroneously degraded injectivity on coarser grids when compared to a sufficiently refined reference grid. In order to correct these errors we propose new formulations of the well index that capture shear-thinning behaviour that the conventional Peaceman calculation fails to address. This modified well index is applied and validated in various scenarios of foam displacement simulation with radial grids. Our proposed solution, used under a simplified form as direct input in reservoir simulation, significantly enhances injectivity estimates without resorting to grid refinements or modifying the shear-thinning model of the injected foam. In most cases it yields results that are closer to those obtained using grid refinements than the Peaceman formula at a much more attractive computational cost. Additional work remains to complete our understanding of injectivity in more complex settings, especially when effects such as foam dry-out and destruction in the presence of oil are as important on sweep efficiency as its shear-thinning behaviour.

Our workflow successfully corrects biases in the estimation of injectivity and yields more accurate results and avoids resorting to time-consuming methods such as grid refinements and physical input data alteration. Moreover it is simple to implement in most commercial simulators and does not require using empirical criteria. However, it bears some limitations which we also discuss.

准确评估注入能力对于任何化学EOR工艺的经济性至关重要。大多数商业模拟器都支持非牛顿行为建模，但由于网格分辨率不足，通常会​​被忽略。实际上，在将稀疏稀疏流体注入到储层中的情况下，如果井格块的空间分辨率太粗糙，则井筒附近的剪切速率和粘度可能难以估计。这导致注入性和经济性方面的偏差，我们将在基于泡沫的位移的背景下进行讨论。

我们首先证明，与足够精细的参考网格相比，对近井眼速度的不良评估会导致在较粗网格上的注入能力错误地降低。为了纠正这些错误，我们提出了新的井指数公式，以捕获传统的Peaceman计算无法解决的剪切稀化行为。修改后的井指数在带有径向网格的泡沫驱替模拟的各种场景中得到应用和验证。我们提出的解决方案以简化形式作为油藏模拟中的直接输入，可显着提高注入量估算值，而无需借助网格细化或修改注入泡沫的剪切稀化模型。在大多数情况下，它产生的结果比Peaceman公式更接近于使用网格细化获得的结果，而计算成本却更具吸引力。在更复杂的环境中，尤其是当诸如泡沫变干和在有油的情况下破坏等影响扫掠效率与降低剪切力的行为同样重要时，还有许多工作要做，以使我们更好地理解注入性。

我们的工作流程成功地纠正了注入性估计中的偏差，并产生了更准确的结果，并且避免诉诸于耗时的方法，例如网格优化和物理输入数据更改。此外，它在大多数商业模拟器中易于实现，并且不需要使用经验标准。但是，它具有一些限制，我们也将对此进行讨论。