| abstract |
Powder-form lubricant additives for water-based drilling fluids which contain from 95 to 30% by weight, based on the total weight of the powder, of highly disperse silicas, from 5 to 70% by weight, based on the total weight of the powder, of one or more fatty acid alkyl esters corresponding to the following general formula. R1COOR2(I) in which R1 is a straight-chain or branched, saturated or mono- or polyunsaturated C9-C21 alkyl or alkenyl radical and R2 is a straight-chain or branched C1-C12 alkyl radical, and/or polyesters obtainable by reaction of di-, oligo- or poly-hydroxy compounds with carboxylic acids and/or distillation residues from the transesterification of native fatty acid esters and, optionally, other additives known for lubricating purposes in quantities of from 0 to 20% by weight, based on the total weight of the powder, and to the use of these powder-form additives in drilling fluids for oil well and mine drilling in quantities of from 0.01 to 5% by weight, based on the total weight of the drilling fluid. |