Dear Mohamed Benhsinat,

WATER RESISTIVITY FROM SALINITY AT ANY TEMPERATURE

Crain's Model is used to convert a lab measured salinity to a formation water resistivity (RW) at any specific temperature (FT) in degrees Fahrenheit. The result is abbreviated as RW@FT throughout this Handbook. You can use equation 5 to convert a salinity to any arbitrary temperature, for example 75 0F or 770F (roughly 250 C) to find the resistivity at laboratory conditions.

      1: FT = SUFT + (BHT - SUFT) / BHTDEP * DEPTH

      2: IF LOGUNITS$ = "METRIC"

      3: THEN FT1 = 9 / 5 * FT + 32

      4: OTHERWISE FT1 = FT

      5: RW@FT = (400000 / FT1 / WS) ^ 0.88

Invert this equation to solve for WS given RW at a a specific temperature FT1.

      WS = 400000 / FT1 / ((RW@ET) ^ 1.14)

WHERE:

  BHT = bottom hole temperature (degrees Fahrenheit or Celcius)

  BHTDEP = depth at which BHT was measured (feet or meters)

  DEPTH = mid-point depth of reservoir (feet or meters)

  FT = formation temperature (degrees Fahrenheit or Celcius)

  FT1 = formation temperature (degrees Fahrenheit)

  RW@FT = water resistivity at formation temperatures (ohm-m)

  SUFT = surface temperature (degrees Fahrenheit or Celcius)

  WS = water salinity (ppm NaCl)

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Dear Mohammed,

are you not sufficiently helped to look at some data given for brine at

https://en.wikipedia.org/wiki/Brine

Regards, Kees

I do not think there can be a generalized empirical relations between salinity for water saturated with NaCl and temperature. It will depend on the environment as well as climatic condition. Based thereon, empirical relations are site specific and as such a function of in situ measurements namely salinity, depth and temperature as well as geomorphology of the site.