Abstract: The present invention relates to a process for preparing fatty acids derived from oils and/pr fats with a phosphorus content below 200 ppm in good yield and with good color and color stability, which process comprises the steps of (A) hydrolytic splitting of degummed oils and/or fats, (B) at least one thermal pre-treatment of a composition comprising crude fatty acids, and (C) high vacuum distillation of the thermally pre-treated composition comprising crude fatty acids.

Abstract: The present invention relates to a method and to a fluid for drilling or workover in a well running through a porous permeable formation, wherein a water-based well fluid circulates in said well. In the method, at most 3% by weight of a composition obtained from fat, or an oil, and an alcohol, is added to the fluid in addition to the conventional constituents for such a fluid, the chain lengths of the acid and alcohol parts being chosen such that the ester thus obtained has sufficient dispersion in water, compatibility with said constituents, does not form an emulsion with the reservoir oil and adsorbs sufficiently on the porous formation.