BAKER HUGHES - Drilling Fluids Reference Manual

Baker Hughes Drilling Fluids
AQUA-DRILL Application (North Sea)
Product Descriptions
Potential applications for the potassium chloride AQUA-DRILL system include a wide spectrum
of wells. To date, the primary application has been for inhibition in tertiary clays. Details of the
fluid system are outlined in the following pages together with general recommendations on
system maintenance. Product applications and concentrations are listed in the following table.
Table 3-24
Recommended Product Concentrations and Applications for the AQUA-DRILL
System
Product Field Concentration Application
Potassium Chloride (KCl) 25 - 40 lbm/bbl Inhibit clay swelling & hydration
MIL-PAC ® LV 2 - 4 lbm/bbl Filtration control
MIL-PAC ® R 0 - 2 lbm/bbl Filtration control
XAN-PLEX ® D 0 - 1 lbm/bbl Rheology control
NEW-DRILL ® 2 - 4 lbm/bbl Improve cuttings integrity
AQUA-COL ® 2% - 5% by vol. Reduced Pressure Transmission
Caustic soda 0.1 - 1 lbm/bbl pH control
MIL-BAR ® As required Density control
KCl – Potassium Chloride can be used at varying concentrations from 0 to 80 lbm/bbl
(saturation). The product is usually shipped in its concentrated form to ease logistics. The level of
inhibition generally increases with increasing concentration of potassium chloride. A typical
curve is illustrated in Figure 3-20 Effect of Temperature on Yield Point at 10% AQUA-
COL TM or tertiary clay. Several wells have been engineered using saturated potassium chloride.
On these wells, only marginal increases in shale inhibition were observed.
In saturated conditions, there is also the potential for formation embrittlement due to the
movement of water from the formation into the drilling fluid. In addition, high chloride levels can
affect log evaluation in reservoir sections. A suitable compromise on inhibition, logistics, and
economics using KCl is to maintain the concentration in the range 25 to 40 lbm/bbl.
Note:
Chloride concentration will affect the cloud point of the polyol in the system and this should
be considered when selecting the salt concentration.
Baker Hughes Drilling Fluids
Reference Manual
Revised 2006 3-83