# Water salinity from density equation

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## Water salinity from density equation

Handy equation to get the formation water (brine) salinity from the density at standard conditions obtained by the data regression with a stage line.

## Math and Physics $C_{mg/l} = 25000 \times (SG_w - 1) \times 62.428$

## Example. Calculating water salinity from density

Example source 

### Input data $\rho_w$ = 65.4 lbm/ft3

Calculate water salinity in weight percent solids?

### Solution $SG_w = \rho_w/62.428=1.0476$ $C_{mg/l} = 25000 (1.0476 - 1) 62.428 = 74289.32$ $C_{ppm} = 74289.32 / 1.0476 = 70913.8$ $C_W = 70913.8 / 10000 = 7.1 %$

## Nomenclature $C_{ppm}$ = water salinity / solids concentration, ppm $C_{mg/l}$ = water salinity / solids concentration, mg/l $C_W$ = weight percent solids, % $SG_w$ = water specific gravity, dimensionless

## See also

Water bubble point pressure
Water compressibility
Water density
Water formation volume factor
Water salinity from density equation
Water solids concentration
Water viscosity
Gas/Water Interfacial Tension