BAKER HUGHES - Drilling Fluids Reference Manual

GLOSSARY OF TERMS
Hydrophilic-Lypophilic Balance (HLB) - Surfactants are characterized according to the “balance”
between the hydrophilic (“water –loving”) and lypophilic (“oil loving”) portions of their molecules.
The hydrophilic-lypophilic balance (HLB) number indicates the polarity of the molecules in an
arbitrary range of 1-40, the the most commonly used emulsifiers having a value between 1 and 20.
The HLB number increases with increasing hydrophilicity. According to the HLB number,
surfactants may be utilized for different purposes.
Function
HLB
Range
Antifoaming Agent 1 to 3
Emulsifier,
water-in-oil
3 to 6
Wetting Agent 7 to 9
Emulsifier,
oil-in-water
8 to 19
Detergent 13 to 15
Solubilizer 15 to 20
Oils also have HLB values assigned; however, this “HLB” is relative as to whether an oil-in-water
emulsion is to be stabilized. Emulsifiers should have similar HLB values to that of the respective oils
in order to achieve maximum stabilization. Mineral oil has an assigned HLB number of 4 when a
water-in-oil emulsion is desired, and a value of 10.5 when an oil-in-water emulsion is to be prepared.
Accordingly, the HLB number of the emulsifier should also be around 4 and 10.5, respectively. The
desired HLB numbers can also be achieved by mixing lypophilic and hydrophilic surfactants. The
overall HLB value of the mixture is calculated as the sum of the fraction times the individual HLB.
Hydrophobe - A substance, usually in the colloidal state, not wetted by water.
Hydrophobic - Descriptive of a substance which repels water.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 15-25