Aya asks PERM:
What will happen if viscosity of oil was not equal to viscosity of water , what is the general effect on trapping of oil drop in a pore doublet throat if the viscosity of oil was large ?
Dr. Jonathan Bryan from PERM Answers:
This is a great question!
The pore doublet model is supposed to show the balance between viscous and capillary forces that will govern flow through either a more narrow tube or a broad tube. The output from calculating flow through the two tubes is the velocity ratio in the small vs. the large tube. When oil and water viscosity are the same, in order for flux in the large tube to exceed flux in the small tube, you would require unrealistically large injection velocities, so on this basis capillary forces are deemed to dominate displacement, and flow will follow the small imbibition pathways. As oil viscosity increases, it gets harder to move oil through the smaller branch of the doublet, so even at lower rates flow will occur through the larger branch of the doublet. For more reference, please see the University of Calgary Thesis by An Mai (2008) titled Mechanisms of Heavy Oil Recovery by Waterflooding. The confluence of this is that, for viscous oil systems, flow may follow the drainage pathways at first, even for a water wet system, because viscous forces are dominant prior to water breakthrough.
Dr. Jonathan Bryan