Preparation and Rheological Properties of Attapulgite Gel for Aqueous Suspensions

Abstract

A new modified attapulgite gel was prepared as a rheological modifier in liquid fertilizer produced by biogas anaerobic fermentation slurry and in oil well drilling fluids. Magnesium oxide showed a great contribution to apparent viscosity and plastic viscosity of attapulgite aqueous suspensions, the main reason perhaps was the inversion of attapulgite rods configuration because of the electrostatic attractive interactions between magnesium oxide particles with positive charges and attapulgite rods with positive charges. This higher viscosity will provide better cuttings carrying capability during drilling fluid circulation especial at low velocity. Dispersants adjusted the electrolyte level of the dispersions, influenced the surface charge of the clay mineral particles, broken up the aggregated configuration of attapulgite gel, and then improved the yield point of the attapulgite suspension. The yield point was declined with increasing dosage of dispersants in present work. Sodium polyacrylate exhibited a superior effect to other dispersants for the rheological behavior of attapulgite gel. Cationic polyacrylamide was an effective additive which affected the gel strength and the gel structure shift on time-dependent at low content. The optimized rheological modifier was obtained in present work which contained 3.5% magnesium oxide, 0.75% sodium polyacrylate, 0.5% alpha sodium naphthol sulfonate, and 0.05% cationic polyacrylamide in the attapulgite clay.