BAKER HUGHES - Drilling Fluids Reference Manual

Water Based Drilling Fluids
Elastomer Testing
The following elastomer tests (Table 3-20 Effects of AQUA-COL ® and AQUA-COL ® D on
Elastomers in a 5% Solution) show the effect of AQUA-COL ® and AQUA-COL ® D on
elastomers in a 5% solution.
Table 3-20
Effects of AQUA-COL ® and AQUA-COL ® D on Elastomers in a 5% Solution
Product Elastomer Time (hrs) Temp (°F) Volume
Change %
Hardness
Change %
AQUA-COL ® Type D 72 250 5.92 5.3
AQUA-COL D ® Type D 72 250 7.50 6.3
AQUA-COL ® Type F 72 250 5.44 4.0
Engineering Guidelines and Comments
Premixed Fluid
North Sea
An existing practice in the North Sea has typically been to utilize concentrated premixes of
AQUA-COL ® to cut down on the number of drums of glycol required at the rig-site and then to
maintain glycol levels at 3% to 5% while drilling. A glycol premix has typically contained 80
lbm/bbl KCl, 7% AQUA-COL ® and 5 lbm/bbl MIL-PAC ® LV. Laboratory tests were conducted
which showed that this mixture produced a cloud point of 6°C (43°F) with complete phase
separation at 8°C (47°F).
Further cloud point measurements have been made to determine the highest levels of KCl and
AQUA-COL ® which could be combined without the risk of phase separation under normal
operating conditions. If the same ratio of salt to glycol as in the original premix is to be
maintained, then 60 lbm/bbl KCl and 5.25% AQUA-COL ® will give a cloud point in the region
of 24°C (75°F). This should be adequate unless there is significant heat input to the fluid resulting
from shear during mixing.
If the KCl concentration is reduced to 50 lbm/bbl, this will allow 7% AQUA-COL ® to be added.
This formulation should be used if the primary requirement is to minimize the number of drums
of glycol shipped to the rig. At 70 lbm/bbl KCl, the highest level of AQUA-COL ® which can be
added without the cloud point dropping below 20°C (68°F) is 2%. Premixes containing more than
60 lbm/bbl KCl should not be used in conjunction with AQUA-COL ® .
Gulf of Mexico
The practice of shipping premixed fluid to the rig is becoming more commonplace. The desired
fluid properties for the anticipated interval are established and a suitable volume of liquid is
prepared. After drilling the cement and performing the formation integrity test, the wellbore is
displaced with the AQUA-DRILL ® fluid. A suitable high viscosity spacer of 30 to 50 bbls is
pumped ahead of the AQUA-DRILL ® fluid.
Reference Manual
Baker Hughes Drilling Fluids
3-78 Revised 2006