US4385999A - Sulfonated gilsonite drilling mud additive

Gilsonite.pro | Gilsonite in Water Based Drilling Muds

SOLTEX ADDITIVE - Chevron Phillips Chemical

Asphasol is shale inhibitor in water base drilling mud

Water based drilling API sulfonated asphalt fluid

Global Sulfonated Asphalt Market: Development History

Sulfonated Asphalt - Polyacrylamide for drag reduction