BAKER HUGHES - Drilling Fluids Reference Manual

Oil / Synthetic Fluids
lower pH. They emulsify freshwater well, but show poor electrolyte tolerance (they lose effectiveness
at low Aw). Thermal stability of the molecule is good as is resistance to alkaline hydrolysis (lime will
not decompose the molecule), but some soaps gel up at low temperatures. All soaps tend to require
additional surfactants at high solids concentration. Tall oil soap (CARBO-TEC or OMNI-TEC) is
particularly good at dispersing DENSIMIX ® (hematite).
Fatty Acids
Figure 5-17
Soap Formation
Fatty acids are the basic components for nearly all emulsifiers and wetting agents used in the
preparation of invert emulsions. Their demand is due primarily to their low cost and availability in
many forms, including crude and refined tall oil, animal pitch, and others.
Tall oil fatty acids are the most common and are obtained as a by-product of the Kraft pulping process,
in which alkaline pulping liquor converts fatty and rosin acids present in soft pines to their
corresponding sodium salts. These sodium salts are then removed and acidified to yield crude tall oil,
which can either be processed into anionic emulsifiers or further refined for use in the manufacture of
non-ionic emulsifiers.
Chemical composition of tall oil varies with the geographical source and species of trees used in
pulping and in the refining process. Oxidation, isomerization, adduct formation, and polymerization
are all factors in the refining process which will influence the final tall oil product.
Baker Hughes Drilling Fluids
Reference Manual
5-22 Revised 2006