Oil-field waters can be subdivided into at least five groups on the basis of their bromine content:

Group I, in which the bromine and total-dissolved-solids content approximates that to be expected from simple concentration of seawater or its dilution with water of low total-dissolved-solids and bromine content.

Group II, which is similar to Group I except for having somewhat more to about twice as much bromine for a specified total-dissolved-solids content. The additional bromine may have been added during early diagenesis.

Group III, in which the total-dissolved-solids content is greater than that of seawater but the bromine content is less than would be expected from simple concentration of seawater. These waters appear to have dissolved halite.

Group IV, in which the total-dissolved-solids content is less than that of seawater but the bromine content is less than would be expected from simple dilution of seawater with water of low total-solids and bromine content. These waters may have been diluted with water having appreciable dissolved solids but low bromine content, or may have been Group III waters diluted with water of low total-dissolved-solids and bromine content.

Group V, which is composed of high-salinity waters having higher bromine content than Group II. Some of these waters are associated with thick salt deposits and appear to be altered bitterns left after salt deposition. The origin of some of these waters is not known.