Power Law rheology – Audit

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Power Law rheology model calculations, release 1a, issued 8 October 2008.


This worksheet takes Fann viscometer readings at 300rpm and 600 rpm. It outputs values of n and K for the Power Law model and plots a graph of Shear Stress against Shear Rate.





Fann 300 rpm dial reading, lb/100ft2

Fann 600 rpm dial reading, lb/100ft2

Fann viscometer 300 rpm reading

Fann viscometer 600 rpm reading

Calculate n and K

If n = 1, the fluid is Newtonian.

If n > 1, the fluid is Dilatent.

If n < 1, the fluid is non-Newtonian (most muds).

Shear stress Pστ = KΓn

Plot shear stress (Pστ) vs shear rate (Γ)

Click here when any values are modified to update the result.


Worksheet references

Version 1 of this worksheet was released on 7 October 2008 by Steve Devereux.

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