On the end-effect correction for Couette type oil-field direct-indicating viscometers for Newtonian and non-Newtonian fluids

V. C. Kelessidis, R. Maglione, G. Bandelis

Research output: Contribution to journalArticle

8 Citations (Scopus)


Analysis and experimental results are presented which quantify the magnitude of end-effects for direct-indicating, narrow gap, rotating cylinder viscometers used extensively in oil-field, for Newtonian and non-Newtonian fluids. Such viscometers have already embedded at manufacturing stage an end-effect correction and give directly the shear stress which does not allow end-effect quantification in a straight forward manner. The presented analysis resolves this problem by estimating the embedded correction, which has been determined as 6.69% of the torque developed along the cylindrical part of the stationary bob of this viscometer. Experimental results with Newtonian and non-Newtonian fluids show that there is no additional end-effect from the bottom of the stationary bob. However, there is additional end-effect contribution from the top section of the bob, which has not been taken into account in the design and manufacturing of the instrument. Its magnitude ranges from 5 to 6% for the Newtonian fluid and the high shear rate range for the non-Newtonian fluid, to 12% for the low shear rate range for the non-Newtonian fluid tested, while the impact on drilling situations is also discussed.

Original languageEnglish
Pages (from-to)37-46
Number of pages10
JournalJournal of Petroleum Science and Engineering
Issue number1-2
Publication statusPublished - 1 Mar 2010



  • Couette viscometer
  • Newtonian
  • end-effects
  • non-Newtonian

ASJC Scopus subject areas

  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology

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