BAKER HUGHES - Drilling Fluids Reference Manual

Baker Hughes Drilling Fluids
Anionic Emulsifiers
Anionic emulsifiers, such as CARBO-TEC ® , are usually prepared by oxidation of crude tall oil. This
oxidation process is shown in Figure 5-18.
H
- H
CH 3 (CH 2 ) 6 - C - CH = CH (CH 2 ) 7 CO 2 H
H
(RH)
•
CH 3 (CH 2 ) 6 - C - CH = CH (CH 2 ) 7 CO 2 H
H
(R•)
Figure 5-18
R• + O 2 -- ROO•
ROO• + RH -- ROOH + R•
2 R• -- R - R
R - OO• + R• -- R - OO - R
R - OO - R -- 2 RO•
RO• + R• -- ROR
Oxidation of Fatty Acids during the Manufacture of Anionic Emulsifiers
The fatty acid of the crude tall oil is converted to a water-insoluble soap by reaction with calcium
hydroxide. Soap formation changes the relative solubility of the fatty acid, whereas air oxidation
increases the surface activity by introducing hydrophilic oxygen groups.
Anionic emulsifiers are used in vast amounts in the detergent industry. They are excellent at reducing
interfacial tension, have good thermal stability, and have resistance to alkaline hydrolysis (some
sulfated or sulfonated oils are an exception).
Non-ionic Emulsifiers
Non-ionic emulsifiers, such as OMNI-MUL TM , are used to provide emulsion stability in drilling fluids
and also to facilitate wetting and dispersion of incorporated solids. These non-ionic emulsifiers tend
to be non-ionic, although they can have slightly cationic tendencies.
Cationics tend to adsorb strongly on mineral surfaces and are excellent oil-wetters. They also function
excellently when emulsifying concentrated calcium chloride solutions. Thermal stability is moderate
and resistance to alkaline hydrolysis is fair to good.
Non-ionics reveal excellent thermal stability and have a high resistance to alkaline hydrolysis. They
also exhibit good electrolyte tolerance. Non-ionics are usually mixed with other surfactants to
maximize oil-base fluid temperature stability.
Baker Hughes Drilling Fluids
Reference Manual
Revised 2006 5-23