Experimental study of influence of temperature, salt, and pH on the rheological behavior of eco-friendly water-based drilling fluid

Abstract

We used nonionic polysaccharides and polyethylene glycols of intermediate molecular weight as environmentally friendly and highly effective additives in water-based bentonite drilling fluids to inhibit syneresis, provide good slurry rheological profiles at elevated temperatures, and maintain these properties in a saline well environment. The effects oResearchers looked into how temperature, salt type and concentration, and pH affect the flow characteristics of an eco-friendly drilling fluid made from two types of Algerian bentonite (Mos-b and Mag-b) and two water-soluble polymers (hydroxyethyl cellulose and polyethylene glycol).  steady shear rheological data to the Herschel-Bulkley (H-B) and Cross models to calculate rheological parameters such as yield stress, consistency index, flow behaviour index, zero shear viscosity, infinite shear viscosity, and characteristic constant of time. The results showed that the highest levels of yield stress, consistency index, and viscosity were found at 65°C for Mos-b and 75°C for Mag-b. These levels went down as the pH went down and when sodium chloride (NaCl) and potassium chloride (KCl) were added to the drilling fluid. The addition of KCl significantly reduced the rheological parameters. The behavior of the base drilling fluid containing Mos-b is more stable and provides superior rheological properties at elevated temperatures and in saline environments compared to the base drilling fluid containing Mag-b.