An improved shear rate estimation using rotating coaxial cylinder Fann viscometer

• Accurate estimation of the rate of shear using Fann 35 rotating coaxial cylinder narrow gap viscometer is proposed.
• The generalized difference equation is used to predict the wall shear rate.
• Synthetic crude oil and suspension of bentonite, hydroxypolyacrylamide, xanthan gum polymer are considered as test fluids.
• Rheology of drilling fluids can also be determined using proposed shear rate formula.

In this study, an improved formula for shear rate calculation has been proposed for drilling fluids, and is estimated using the generalized difference equation for the rotating narrow gap coaxial cylinder Fann Viscometer under purely steady, laminar and isothermal tangential fluid flow condition. Rotor rotating speeds and bob dial readings are the important input variables for shear rate prediction. The proposed equation was used to calculate shear rates accurately for several non-Newtonian fluids, mainly, synthetic crude oil, aqueous bentonite suspension, aqueous hydroxypolyacrylamide solution and aqueous xanthan gum polymer solution. Finally, the predicted consistency plots were compared with those which are obtained from the conventional method of estimating the rate of shear for drilling fluids.

Figure optionsDownload as PowerPoint slide