Performance of Perlite as viscosifier in manganese tetroxide water based-drilling fluid

Abstract

The rheological properties of drilling fluids are considered critical criteria in mud design and selection. Rheological parameters greatly impact various drilling fluid functions, including the ultimate workover, carrying capacity, cuttings transportation, minimizing the loss circulation, etc. Therefore, different additives were used to control the rheological properties and improve the other drilling fluid parameters such as filtration and filter cake properties. In this work, amorphous glass rock known as Perlite was examined as an additive for manganese tetroxide water based-drilling fluids. Two dosages of manganese tetroxide were prepared namely 250 and 350 lb/bbl. The rheological properties were evaluated and implemented to assess the fluid behavior using four different models including Bingham plastic, power-law, Herschel-Bulkley and Robertson-Stiff models. In addition, the impact of Perlite on the manganese tetroxide drilling mud at varied densities were investigated in term of pH value and the sagging tendency. The obtained results showed that as function of adding the Perlite, the plastic viscosity was reduced while the yield point increased. The three parameters’ models including Herschel-Bulkley and Robertson-Stiff models were the best in describing the drilling fluid with and without the Perlite. It was also observed that the Perlite has negligible effect on pH and the sagging factor was maintained in the safe window. Moreover, the filtration and the filter cake characteristics were enhanced upon the Perlite addition in both mud densities.