Polymer Flooding
To what extent, the effects of non-Newtonian fluid rheology of polymer fluids (such as HPAM or Xanthan) on flow dynamics and its associated up-scaling from pore-scale mechanisms to a larger field-scale implementation would remain to be compromised, if the actual non-Newtonian rheology [the apparent viscosity remaining as a constant @ lower shear rates {upper Newtonian plateau}, and then, the apparent viscosity getting mitigated with shear rates roughly following a power law; and the apparent viscosity reaching a lower Newtonian plateau @ higher shear rates] of polymers leading to a non-linear relationship between flow rate and pressure gradient remains ignored and still directly applying linear Darcy law towards quantifying the permeation of polymer fluids in an oil reservoir?
On the other hand, how easy/complex to simultaneously take into account both
(a) complex rheology of polymer fluids;
as well as
(b) complex topology of the pore-network geometry?
How critical is to include
the effects of increased channeling induced by shear-thinning rheology of polymers
rather than simply considering
the flow paths of power-law polymer fluids remaining similar to that of Newtonian fluids?
Dr Suresh Kumar Govindarajan
Professor [HAG]
IIT Madras
09-Macrh-2025
Hello Suresh Kumar Govindarajan ,
These are indeed challenging questions and in addition we shouldn't overlook the surface tension / capillary pressure effects in the pores between the capillary wall and the HPAM or Xantham gels. This lack of wettability can be significant for hydrophobic surfaces. I'm not sure if you're considering a fully wetted system or initial flow?
Regarding the question of whether the flow paths of power-law polymer fluids remaining similar to that of Newtonian fluids? This would not be the case, but rather would be solved by calculating the volumetric flow rate of the fluids through specific diameter capillaries at a given stress.
Shear rate = 4Q/Pi.r^3 Shear stress = p.r / 2L Viscosity(Eta) = Stress/ rate
(where Q is volumetric flow rate, r is the radius of the pore, p is the pressure drop across the pore and L is the length of the pore.)
Q = Shear rate / 4.Pi.r^3, therefore Q = p.r / 2L.Eta
I'm sorry that I can't really speak about the topological effects or capillary/surface tension effects in detail, but I believe that people have simulated similar flows using a capillary rheometer with a porous die and pressure transducer above the die. The flow rate is directly controlled by the piston speed and diameter, and the pressure is measured with a transducer right above the die. Initially you'd "calibrate" the porous block by passing a known Newtonian fluid (water or oil) through it to calculate the overall diameter of the combined pores. A pore count will allow a more accurate shear rate calculation. This known porous material can then be used to run a complex fluid through it.
I hope this helps!
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