An Experimental Study of Influence of Salt Concentration, Mixing Time, and pH on the Rheological Properties of Pre-Hydrated Bentonite Slurries Treated by Polymers

Abstract

The aim of this study is to investigate the influence of pH between 8.5 and 12.5, mixing time, and of NaCl, KCl, and CaCl₂ concentration over the range of 0% to 20% on the rheological properties of pre-hydrated bentonite slurry following by treatments with different polymers. Viscometric data gathered by viscometer described well by the Herschel-Bulkley rheological model for all fluids tested. Increasing salt concentration and pH led to some significant changes in the rheological properties. Moreover, adding saturated salt to pre-hydrated slurry resulted in increasing shear stress and plastic viscosity for all fluids.

Keywords:

• Bentonite
• drilling fluid
• Herschel-Bulkley
• pH
• rheology

Acknowledgments

The authors acknowledge Hamoole and Shavali for their guidance regarding experimental tests. They also would like to gratefully acknowledge National Iranian Drilling Co. for financial support.