Shojaei Mohammad Javad, Rodríguez de Castro Antonio, Méheust Yves, Shokri Nima
The School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK.
Arts et Métiers ParisTech, 51006 Châlons-en-Champagne, France; Laboratoire MSMP - EA7350, Rue Saint Dominique, 51006 Châlons-en-Champagne, France.
J Colloid Interface Sci. 2019 Sep 15;552:464-475. doi: 10.1016/j.jcis.2019.05.068. Epub 2019 May 21.
There has recently been renewed interest in understanding the physics of foam flow in permeable media. As for Newtonian flows in fractures, the heterogeneity of local apertures in natural fractures is expected to strongly impact the spatial distribution of foam flow. Although several experimental studies have been previously performed to study foam flow in fractured media, none of them has specifically addressed that impact for parallel flow in a realistic fracture geometry and its consequences for the foam's in situ shear viscosity and bubble morphologies. To do so, a comprehensive series of single-phase experiments have been performed by injecting pre-generated foams with six different qualities at a constant flow rate through a replica of a Vosges sandstone fracture of well-characterized aperture map. These measurements were compared to measurements obtained in a Hele-Shaw (i.e., smooth) fracture of identical hydraulic aperture. The results show that fracture wall roughness strongly increases the foam's apparent viscosity and shear rate. Moreover, foam bubbles traveling in regions of larger aperture exhibit larger velocity, size, a higher coarsening rate, and are subjected to a higher shear rate. This study also presents the first in situ measurement of foam bubbles velocities in fracture geometry, and provides hints towards measuring the in situ rheology of foam in a rough fracture from the velocity maps, for various imposed mean flow rates. These findings echo the necessity of considering fracture wall when predicting the pressure drop through the fracture and the effective viscosity, as well as in situ rheology, of the foam.
最近，人们对理解泡沫在多孔介质中流动的物理过程重新产生了兴趣。至于裂缝中的牛顿流体流动，天然裂缝中局部孔径的不均匀性预计会强烈影响泡沫流动的空间分布。尽管此前已经进行了几项实验研究来探究泡沫在裂缝介质中的流动，但没有一项研究专门针对实际裂缝几何形状中的平行流动的这种影响及其对泡沫原位剪切粘度和气泡形态的影响。为此，通过以恒定流速将六种不同质量的预生成泡沫注入具有特征明确的孔径图的孚日砂岩裂缝复制品中，进行了一系列全面的单相实验。将这些测量结果与在具有相同水力孔径的赫勒-肖（即光滑）裂缝中获得的测量结果进行了比较。结果表明，裂缝壁粗糙度会显著增加泡沫的表观粘度和剪切速率。此外，在较大孔径区域中移动的泡沫气泡具有更高的速度、更大的尺寸、更高的粗化速率，并且受到更高的剪切速率。这项研究还首次对裂缝几何形状中泡沫气泡的速度进行了原位测量，并为根据不同施加平均流速下的速度图测量粗糙裂缝中泡沫的原位流变学提供了线索。这些发现呼应了在预测通过裂缝的压降以及泡沫的有效粘度和原位流变学时考虑裂缝壁的必要性。
