Synthesis and characterization of Tunisian organoclay: Application as viscosifier in oil drilling fluid

Abstract

In this study, the viscosifiers for diesel oil drilling fluid were prepared using Tunisian clay modified with cationic surfactant for five concentration levels from 0.5 to 4.0 times the cationic exchange of purified clay (CEC). The organo-modified clay samples were characterized by X-ray diffraction (XRD), Infrared spectroscopy (FTIR), scanning electron micrography (SEM) and specific surface area (BET model). Oil–clays suspensions were investigated using polarized light optical microscopy (PLOM) and double cone rheometer. The influence of surfactant concentration on rheological properties of suspensions is related to the different microstructures development which depend on surfactant arrangement in the interlayer of clay. The results showed the growth of yield stress and consistency coefficient as the surfactant concentration is increased and the best behaviors were observed for the 3.0 CEC concentration. This sample was tested for two weight percents (5 and 10wt%), the higher Herschel Bulkley parameters (τ0=3.6Pa, K=0.397 and n=0.85) were found for the organoclay at 10wt%. The latest sample has the high thixotropy loop area so can be used as viscosity enhancer for the oil drilling fluid.