Modification of bentonites with nonionic surfactants for use in organic-based drilling fluids

• Nonionic surfactants were effective in the intercalation of interlayer spaces.
• Combined use of organophilization agents produced the best results.
• Clays unsuitable for water-based muds can be used as organoclays in oil-based fluids.

The use of organophilic bentonites as additives in organic-based drilling fluids has long been a subject of study, but few studies have focused on the modification of these clays with nonionic surfactants. The advantage of nonionic surfactants over ionic ones is that they improve the thermal and chemical properties of organoclays (OC), and are also more readily biodegradable. The work described here involves a study of bentonites modified by nonionic surfactants, aiming at their use as dispersants in the composition of organic-based drilling fluids. The organophilization process was analyzed by X-ray diffraction and thermogravimetry, and the interaction of organoclays with the solvent medium was assessed based on the swell index and the determination of the apparent viscosity of clay-containing dispersions. The results indicate an effective intercalation of the nonionic surfactants in organoclays, and the content of incorporated surfactants was also quantified. The swelling results demonstrate chemical compatibility between diesel and kerosene organic media and the organoclays produced. From the rheological standpoint, some of the organophilic clay samples present a potential for use as raw materials for additives in organic-based drilling fluids, despite being considered of poor quality when analyzed for water-based drilling fluids.