BAKER HUGHES - Drilling Fluids Reference Manual

Oil / Synthetic Fluids
One of the most important factors in the formulation of the amide-type non-ionic emulsifier is the
selection of the cross-linking agent. Shown below in Figure 5-19 is the manufacturing process for
polyamide emulsifiers.
Figure 5-19
General Polyamide Emulsifier Synthesis
Colloids
Organophilic Clay
Organophilic clays (CARBO-GEL ® and CARBO-VIS TM ) are the most common gelling and
suspending additives used in oil-base fluids. Organophilic clays are usually formed by reacting a
quaternary ammonium chloride (quat) with sodium bentonite. The cationic quat replaces a sodium ion
on the surface of the bentonite.
This effectively renders the surface oil wettable and allows the hydrocarbons to wet and penetrate the
clay lattice structure and swell the organophilic clay to dispersion. While organophilic bentonite is the
most common example, organophilic hectorite and sepiolite can be used as well.
To obtain the full potential rheology of any organoclay, both shear and heat are required. Organoclays
are manufactured by either a “dry” or “wet” process. The latter method produces purified clays which
are more thermally stable, especially the hectorite base organoclays, which are more consistent in their
performance. By varying the quat chemistry and clay type, a wide variety of organoclays are available
which can be used with various base oils and in various temperature ranges. Maximum thermal
stability of organoclays varies between 285°F (140°C) and 400°F (204°C). The cost of the organoclay
grades increases with thermal stability.
Baker Hughes Drilling Fluids
Reference Manual
5-24 Revised 2006