# Water density

## Formation water density

Water density correlation in the PVT software at pengtools.com

The density of formation water (brine) at standard conditions (14.7psia & 60°F):

$\rho_{wSC} = C_{mg/l}/25000 + 62.428$[1]

The density of formation water (brine) at reservoir conditions:

$\rho_{wR}=\rho_{wSC}/B_w$[1]

## Example. Calculating formation water density

Example source [1]

### Input data

$C_{mg/l} = 74289.3$
$B_w = 1.022$ at 3176 psia and 165°F

Estimate the density of the brine at standard conditions (14.7psia & 60°F) and at 3176 psia and 165°F?

### Solution

$\rho_{wSC} = 74289.3/25000 + 62.428 = 65.4 lb_m/ft^3$
$\rho_{wR} = 65.4/1.022= 64 lb_m/ft^3$

The solution is also available in the PVT software model at [The solution is available in the PVT calculator software model at www.pengtools.com

## Nomenclature

$B_w$ = water formation volume factor, res bbl/STB
$C_{mg/l}$ = water salinity or solids concentration, mg/l
$\rho_{wSC}$ = water density at standard conditions, lbm/ft3