BAKER HUGHES - Drilling Fluids Reference Manual

RESERVOIR APPLICATION FLUIDS
6. Amount of fresh water incorporated:
W d
=
450 14.5 – 14.1
----------------- ( ------------------------ ) = 29.2 bbl
14.5 – 8.335
CaCl 2 addition
CaBr 2 required
=
=
(---------------------------- 29.2)121.3
= 4,933 lbs
.718
( 29.2
---------------------------- )248.9
= 10,122 lbs
.718
Final volume
=
450 + 29.2
------------------------- = 667 bbl
.718
Therefore, 4,933 lbs of CaCl 2 and 10,122 lbs of CaBr 2 added to 450 bbl of 14.1 lb/gal fluid will
yield 667 bbl of original 14.5 lb/gal brine
Salt Solubility vs. Freeze Depression
Crystallization
Ice Crystals
Fresh water ice crystals begin to form when the solution drops below the freeze depression curve.
In other words, salts dissolved in water below their maximum solubility limit for that solution
depress the freezing point of the solution.
Salt Crystals
These crystals occur when a particular salt is added above its maximum solubility at a particular
temperature, or when the temperature drops below the curve at which the salt can be in solution.
Problems
Several potential problems can be caused by the formation of ice and salt crystals.
• Density will begin to decrease as ice forms or salt comes out of solution and is removed as
the fluid circulates over the shakers.
• Formation damage can occur as salt crystals plug the pore throats.
• Viscosity increases with crystallization due to solids crowding.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 6-48