Rheo-SAXS investigation of organoclay water in oil emulsions

• Rheo-SAXS experiments are applied on organoclays water in oil emulsion under shear flow.
• Stable emulsions exhibit a shear-thinning behavior with a shear stress.
• The nature and the concentration in OC influence the viscosity under flow.
• Under shear flow, the structure and isotropic distribution of OC particles are maintained.

Organoclay (OC) loaded macroemulsions are systems used worldwide as drilling-fluid in oil extraction. SAXS and viscosity measurements (Rheo-SAXS) are simultaneously performed on OC loaded water in dodecane emulsions (W/D = 10/90), at different shear rates in the range 0.1–1000 s−1. The role of three OC (VG69, Bentone and Geltone) was investigated at different concentrations (<3.5%, m/m). The stabilization of W/D emulsions implies co-addition of OC > 2% (m/m) and surfactants. These emulsions exhibit a shear thinning behavior with a yield stress. The dispersion state of the clay mineral particles inferred, with a fit of SAXS profiles using a scattering model of stacking of N core-layer platelets. The structure of clay mineral particles is unchanged under flow and clay mineral particles are isotropically dispersed under a shear rate <1000 s−1. Bentone with the best ability to swell in dodecane, has the large impact on viscosity.

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