Oligoglycerol fatty acid ester lubricant additives for drilling fluids

1. A lubricant additive in oil-based drilling mud composition comprising an oligoglycerol fatty acid esters, produced from

(a) an acid component, selected from

(a1) fatty acids of the general formula (I)

R—COOH  (I)

in which R stands for a saturated or unsaturated, branched or linear alkyl- or alkenyl radical with 7 to 21 C atoms, and/or

(a2) dicarboxylic acids and/or

(a3) dimer fatty acids and/or

(a4) oligomer fatty acids and/or

(a5) hydroxy fatty acids; and

(b) a polyol component, which is selected from oligoglycerols or alkoxylates of oligoglycerols;

wherein said oil-based drilling mud comprises paraffin; and

wherein said paraffin comprises 13 to 22 carbon atoms and other hydrocarbons including alpha olefin, internal olefins.

2. The lubricant additive in oil-based drilling mud composition according to claim 1 , characterized in that the fatty acids of formula (I) are selected from unsaturated, linear fatty acids.

3. The lubricant additive in oil-based drilling mud composition according to claim 1 , characterized in that oligoglycerol fatty acids esters are selected, which were produced by conversion of oligoglycerols of formula (II)

in which n denotes a number between 2 and 10, with fatty acid mixtures;

wherein said fatty acid mixtures comprise mixtures of saturated and unsaturated fatty acids and/or dicarboxylic acid and/or dimeric and/or oligomeric fatty acids.

4. The lubricant additive in oil-based drilling mud composition according to claim 1 , characterized in that tri-, tetra- and/or pentaesters of the oligoglycerols are used.

5. The lubricant additive in oil-based drilling mud composition according to claim 1 , characterized in that oleic acid or tall oil fatty acids or mixtures thereof are used as fatty acid for the esterification.

6. The lubricant additive in oil-based drilling mud composition according to claim 1 characterized in that in the esterification, the molar ratio of fatty acids:oligoglycerol lies in the range of from about 5:1 to about 1:1.

7. The lubricant additive in oil-based drilling mud composition according to claim 1 characterized in that in the esterification, the molar ratio of dimer fatty acids or oligomeric fatty acids to oligoglycerol lies in the range of from about 1:1 to about 1:2.

8. The lubricant additive in oil-based drilling mud composition according to claim 1 , characterized in that the oligoglycerol esters are used as additive in a mixture with surfactants, hydrocarbons, fatty alcohols, fatty acid esters and/or fatty acids or glycerol, triglyceride or glycols.

9. A method for improving the lubricating effect of oil-base drilling muds wherein oligoglycerides according to the description in claim 1 are added to the muds in quantities of about 0.1 to about 10% by weight.

10. A lubricant additive in oil-based drilling mud composition comprising an oligoglycerol esters, produced from

(a) an acid component, selected from

(a1) fatty acids of the general formula (I)

R—COOH  (I)

in which R stands for a saturated or unsaturated, branched or linear alkyl- or alkenyl radical with 7 to 21 C atoms, and

(b) a polyol component selected from oligoglycerol or alkoxylates of oligo glycerol.

11. The lubricant additive in oil-based drilling mud composition according to claim 10 characterized in that in the esterification, the molar ratio of elements a:b lies in the range of from about 5:1 to about 1:1.

12. The lubricant additive in oil-based drilling mud composition according to claim 10 wherein the acid component is from oleic acid or tall oil fatty acid.

13. The lubricant additive in oil-based drilling mud composition according to claim 10 wherein the acid component is oleic acid.

14. The lubricant additive in oil-based drilling mud composition according to claim 10 wherein the polyol component is selected from oligoglycerol.

15. The lubricant additive in oil-based drilling mud composition according to claim 10 wherein the acid component is tall oil fatty acid.