ABSTRACT
The flow characteristics of fluids in porous solids are important for these systems. The flow of hydraulic fracking fluid through shale matrix is the primary step. This is the same as any fluid flow through a porous media, that is, capillary pressure. The interaction between a liquid and any solid will form curved surfaces, which, being different from a planar fluid surface, give rise to capillary forces. The behavior of liquids in narrow tubes is one of the most common examples in which capillary forces are involved. Physical chemistry studies are based on the molecular interactions in liquids that are responsible for their physico-chemical properties such as boiling point, melting point, and surface tension. The mechanical equilibrium at liquid surfaces has been investigated for over a century. The liquid surface has been considered as a hypothetical stretched membrane, this membrane being termed the surface tension.
