Definition(s)
Sodium Absorption (SAR)
“Sodium Adsorption Ratio (SAR)” means the index which indicates the relative abundance of sodium ions in solution as compared to the combined concentration of calcium and magnesium ions. It is calculated as follows:
SAR = (Na ppm/23.0) / sq. root of [{(Ca ppm/20.02) + (Mg ppm/12.16)} / 2]
where Na=Sodium, Ca=Calcium. Mg=Magnesium.
Source: Corporation Commission, Oil and Gas Conservation, Oklahoma Administrative Code 165:10, February 2013. Regulations