Chemistry of Rustler fluids

Water chemistry determinations were performed by the US Geological Survey on water samples collected from the three fluid-bearing zones of the Rustler Formation from 20 testholes at and adjacent to the WIPP from 1976 to 1980. Analysis of the data demonstration that the three fluid-bearing zones are chemically separate from one another at the WIPP site, but progressively merge towards the west into Nash Draw. The fluids present at the Rustler-Salado contact approach saturation with respect to sodium chloride. Magnesium replaces sodium as the prevalent cation east of the WIPP site: this boundary may represent the approximate limit of salt dissolution in the Rustler Formation. Three zones (areally) of differing predominant chemical constituents are present in the Culebra Dolomite. Groundwater flow paths cross these zones, changing the Culebra water from a sodium choride brine to a moderately saline calcium sulfate water. The Culebra waters are undersaturated with respect to halite and have the capacity of dissolving more halite from the Rustler or the Salado formations. The major ions present in the fluids in the Magenta Dolomite are predominantly sodium and chloride. A few wells have sulfate rather than chloride as the predominant anion