BAKER HUGHES - Drilling Fluids Reference Manual

RESERVOIR APPLICATION FLUIDS
In 1984, Dow Chemical (Krook and Boyce, SPE 12490, 1984) developed experimental data for
input into a working method for determining the effect of temperature and pressure on brine
density. The model used the following equation.
Where:
ΔP t = (ΔP d x 10 -3 )β -– (ΔT x 10 -2 ) α
ΔP t = Change in density resulting from temperature and pressure, lb/gal
ΔP d = Pressure difference, psi
ΔT = Temperature difference, °F
β = Compressibility factor, lb/gal/100 °F
α = Expansion factor, lb/gal/1000 psi
If the values of α and β are known for a particular brine, the change in density can be calculated.
Although the industry had taken a step forward in estimating clear brine downhole densities, the
compressibility and expansion factors for most mixed-salt brine combinations were unavailable.
The ESD Calculator has resolved this issue and developed a database of compressibility and
expansion factors for most of the mixed-salt brine compositions. To complete the program, the
Baker Hughes Drilling Fluids ESD Calculator provides calculated density values at 20 different
TVD increments along the wellbore.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 6-107