the present disclosure relates to a biodegradable lubricant composition , notably intended to be incorporated as an oil phase with high lubricating power in a drilling fluid or mud . this composition may be in a drilling fluid or as a fluid for fracture of underground formations . these muds or fluids contained in the composition of the present disclosure are particularly suitable for very deep drillings , offshore in deep water and / or sidetracked drillings or with a long shift .