Page 197 - Well Control for Completions and Interventions

190 Well Control for Completions and Interventions

Table 5.1 Brine density
Brine type Formula Density range Density range
(ppg) (SG)
Sodium chloride NaCl 8.4 10.0 1 1.20
Potassium chloride KCl 8.4 9.7 1 1.164
Ammonium chloride NH 4 Cl 8.4 8.9 1 1.06
Sodium bromide NaBr 8.4 12.7 1 1.52
Sodium chloride/ NaCl/NaBr 8.4 12.5 1 1.50
bromide
Sodium formate NaCOOH 8.4 11.1 1 1.33
Potassium formate KCOOH 8.4 13.3 1 1.60
Cesium formate CsCOOH 13.0 20.0 1.56 2.40
Potassium/cesium KCOOH/ 13.0 20.0 1.56 2.40
formate CsCOOH
Sodium/potassium NaCOOH/ 8.4 13.1 1 1.57
formate KCOOH
Calcium chloride CaCl 2 8.4 11.3 1 1.36
Calcium bromide CaBr 2 8.4 15.3 1 1.84
Calcium chloride/ CaCl 2 /CaBr 2 8.4 15.1 1 1.81
bromide
Zinc bromide ZnBr 2 12.0 21.0 1.44 2.52
Zinc/calcium bromide ZnBr 2 /CaBr 2 12.0 19.2 1.44 2.30

The densities listed in Table 5.1 can only ever be approximate, since
density varies with temperature, and to a lesser extent, pressure.
Increasing temperature causes fluid to expand, with a consequent decrease
in density. Increasing pressure causes a density increase.
In addition to density requirements, brine selection must also take
account of the true crystallization temperature (TCT). Brine should be
compatible with both the formation and formation fluids, as well as with
any exposed completion components; all elastomers and metal. Selecting
a compatible brine that has both a suitable crystallization temperature,
and is compatible with the formation and the completion, requires an
iterative approach and can require extensive testing.

5.3 BRINE DENSITY
Where brine forms the primary well control barrier, calculating the
correct density is crucial. Density calculations will always be the first step
in the brine selection process. Brine must have sufficient density to