BAKER HUGHES - Drilling Fluids Reference Manual

Baker Hughes Drilling Fluids
Table 3-18
Basic Properties of Glycols Used in the AQUA-DRILL System
Glycol Density Mol. Wt. Freezing
Point °F
pH at 10%
Flash
Point °F
AQUA-COL 8.4 500 < 10 7 - 10 > 200
AQUA-COL D 8.5 380 < 15 7 - 10 > 250
AQUA-COL S 9.1 500 < 10 7 - 10 > 212
Glycol and glycerol have been used in water-base drilling fluids for many applications.
Chemically related to alcohols, glycols have many of the properties of diesel and mineral oils, but
contribute virtually no toxicity to the fluid. Having low vapor pressure at normal temperatures,
glycols are not an inhalation hazard. The similarities between glycols and alcohols are shown
below.
Table 3-19
Chemical Similarities Between Glycols and Alcohols
Common Name Chemical Name Chemical Structure
Wood Alcohol Methanol OH
Drinking Alcohol Ethanol OH
CH 3
CH 3
CH 2
Rubbing Alcohol Isopropanol OH
Antifreeze
Ethylene Glycol
Propylene Glycol
CH 3 CH CH 3
OH
CH 2
OH
OH
CH 2
OH
CH 3
CH CH 2
Glycerin Glycerol OH OH
OH
CH 2
CH CH 2
The chemistry of glycol additives can be varied to meet the demands of the product application.
This formulation flexibility makes the AQUA-DRILL system the ideal fluid for many
applications, including:
• reducing pore pressure transmission into the shale matrix, thus stabilizing the shale
• use on operations in environmentally-sensitive areas
The full benefit and cost-effective use of glycols can only be realized when their use is
engineered correctly. The chemistry of the glycols is such that they possess the physiochemical
characteristics that make them capable of producing a cloud point (coming out of solution)
behavior in the right circumstances. It is the engineering ability to control this physiochemical
phenomenon that can make a mud a success or a failure.
Cloud point, or more precisely the Cloud Point Temperature (CPT), is defined as that temperature
where glycol comes out of solution as small dispersed droplets forming a “cloud”. The cloud
point can also be referred to as the Lower Consulate Solution Temperature (LCST). The ability
to “cloud” reduces consumption of glycol because as fluid cools, glycol goes back into solution
and is not removed with cuttings.
Baker Hughes Drilling Fluids
Reference Manual
Revised 2006 3-69