Influence of solids concentration and solid/polymer interaction on the apparent viscosity of drilling fluids

Abstract

Drilling fluids perform several functions such as lubrication and cooling of the drill bit, carrying the cuttings to the surface and also maintaining the stability of the well. The physicochemical characteristics of solid particles affect the drilling fluid properties, such as density, chemical composition, and surface charge. In this research, the effects of concentration, surface charge, and adsorption of different solid additives (Barite, Calcite, and Glass spheres) in carboxymethylcellulose (CMC) aqueous solutions were evaluated to quantify its influence on the apparent viscosity of drilling fluids. A study of the polymer hydration time was also carried out. The suspensions were characterized and analyzed by the rheological parameters, the morphology, the surface charge, and the chemical composition. The results showed that suspensions with solids concentration higher than 25% (m/v) presented an increase of the frictional effect of solids, leading to a significant increase in the apparent viscosity of the suspensions. The morphology of the glass spheres facilitated the fluid flow, leading to the lowest apparent viscosity among the suspensions. Ca 2+ ions from calcite solids reduced the energy barrier against flocculation, making the apparent viscosity of calcite suspensions the highest. The barite suspensions showed the highest zeta potential value (in modulus) among all suspensions. The appearance of two bands related to the carbonyl in the FTIR spectrum of barite suspensions proves chemical adsorption with the CMC polymer, justifying its lower apparent viscosity compared to calcite suspensions.

Asymmetrical Dependence of {Ba2+}:{SO42–} on BaSO4Crystal Nucleation and Growth in Aqueous Solutions: A Dynamic Light Scattering Study

“…Common chemicals that have been used as additives for the inhibition of barite are phosphonates and compounds with polyphosphino-carboxylic functional groups − as they are stable over a wide range of temperatures and pH, inhibit scale at low concentrations, target many types of scale, and their concentration is easily determined by colorimetric techniques . However, most studies investigated the bulk phase, such as in situ jar tests, and research focusing on the surface chemistry in industrial settings has only taken place recently. − The main goal of those studies was to relate surface chemistry processes to the interaction behavior of barite crystals with distribution piping material and drilling fluids under specified physicochemical conditions.…”

“… 69 However, most studies investigated the bulk phase, such as in situ jar tests, and research focusing on the surface chemistry in industrial settings has only taken place recently. 70 − 75 The main goal of those studies was to relate surface chemistry processes to the interaction behavior of barite crystals with distribution piping material and drilling fluids under specified physicochemical conditions.…”