A temperature-stable, non eco-toxic oil-base well fluid that is
particularly suitable for high pressure/high temperature drilling
comprises an emulsification system comprising at least one superamide
that may or may not be polyalkoxylated, optionally associated with a
non-ionic co-surfactant. The oil-base well fluid comprising such a system
can be used at temperatures of up to about 200.degree. C. due to the
production of highly temperature-stable reverse emulsions.