Oligoglycerol fatty acid ester thickeners for oil-based drilling fluids
Oligoglycerol esters of fatty acids, preferably of unsaturated fatty acids, can be used as thickeners in oil-based drilling mud compositions. The oligoglycerides are preferably employed in invert drilling muds, the oily phase of which contains paraffins.
1. Thickeners in oil-based drilling mud compositions comprising oligoglycerol fatty acid esters prepared from an acid component (a) chosen from (a1) fatty acids of the general formula (I)
R—COOH (I)
in which R represents a saturated or unsaturated, branched or linear alkyl or alkenyl radical having 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) oligoglycerols or alkoxylates of oligoglycerols;
wherein said oil-based drilling muds are invert drilling muds; and
wherein said invert drilling muds comprise paraffins in the oily phase.
2. The thickeners in oil-based drilling mud compositions according to claim 1 , characterized in that the fatty acids of the formula (I) are chosen from unsaturated linear fatty acids.
3. The thickeners in oil-based drilling mud compositions according to claim 1 characterized in that oligoglycerol fatty acid esters which have been prepared by conversion of oligoglycerols of the general formula (II)
wherein 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 acids and/or dimeric and/or oligomeric fatty acids.
4. The thickeners in oil-based drilling mud compositions according to claim 1 characterized in that oleic acid or tall oil fatty acids or mixtures thereof are chosen as the fatty acid.
5. The thickeners in oil-based drilling mud compositions according to claim 1 characterized in that the molar ratio of fatty acids:oligoglycerol in the esterification is in the range of from about 5:1 to about 1:1.
6. The thickeners in oil-based drilling mud compositions according to claim 1 characterized in that the molar ratio of dimeric fatty acids or oligomeric fatty acids to the oligoglycerol in the esterification is in the range of from about 1:1 to about 1:2.
7. The thickeners in oil-based drilling mud compositions according to claim 1 characterized in that the tri-, tetra-, pentaesters of the oligoglycerols or mixtures of these esters are employed.
8. The thickeners in oil-based drilling mud compositions according to claim 1 characterized in that the oligoglycerol esters are employed as an additive in a mixture with surfactants, hydrocarbons, fatty alcohols, fatty acid esters, fatty acids, glycerol, triglycerides and/or glycols.
9. A method for the thickening of oil-based drilling mud compositions, characterized in that oligoglycerol esters according to the description in claim 1 are added to the drilling mud compositions in amounts of from about 0.1 to about 10 wt. %.
10. Thickeners in oil-based drilling mud compositions comprising oligoglycerol fatty acid esters prepared from an acid component (a) chosen from
(a1) fatty acids of the general formula (I)
R—COOH (I)
in which R represents a saturated or unsaturated, branched or linear alkyl or
alkenyl radical having 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) oligoglycerols or alkoxylates of oligoglycerols wherein a mixture of oligoglycerides with glycerol is employed.