Optimization of invert emulsion oil-based drilling fluids performance through heterocyclic imidazoline-based emulsifiers

In this work six structurally related imidazoline oligomers based on the reaction of liner polyamine with saturated and unsaturated long alkyl chains (C18 oleic and stearic) fatty acids were prepared, followed by a quaternization reaction to produce new conventional and gemini imidazolinium quaternary salts. The chemical structures of prepared amphiphiles were confirmed via spectroscopic methods and elemental microanalysis, also, the prepared emulsifier's characterization has been studied through static interfacial tension, visual and microscopic examination of prepared emulsification systems. The static interfacial tension measurements show a high ability to reduce interfacial tension values between diesel oil and water. The visual and microscopic examination gave evidence of a multilayer interface around emulsion particles and an increase of emulsion droplets size as a function of time with acceptable emulsion stability and phase separation. For both oil-based mud cost and diesel oil toxicity, this article brings to light many important aspects of designing new emulsifiers for low toxicity invert emulsion muds with lower diesel oil content. The prepared emulsifiers were mixed to be investigated and evaluated as primary emulsifiers package to formulate the invert emulsion oil-based muds (IEOBMs). The electrical stability, rheological properties, and filter loss were evaluated before and after hot roller aging and compared with the reference mud sample formulated from the commercial-grade emulsifiers. The experimental investigations conducted based on the Herschel-Bulkley rheological model showed good rheological behavior compared to the reference mud sample, high resistance to the deformation that occurred to prepared mud systems due to hot roller aging, good electrical stability, and high pressure-high temperature filtration loss values.

Automated summary

In this study, six structurally related imidazoline oligomers were synthesized through chemical methods, which showed a high ability to reduce interfacial tension values between diesel oil and water, and exhibited acceptable emulsion stability and phase separation behavior. The experimental investigations demonstrated good rheological behavior, high resistance to deformation, good electrical stability, and high pressure-high temperature filtration loss values of the prepared emulsifiers when used as primary emulsifiers in invert emulsion oil-based muds.