A first wellhead fluid sample is collected from a petroleum well. Multiple geochemical water analysis (GWA) tests are preformed to form GWA water analysis data. The GWA tests determine physical properties of, and one or more geochemical water element (GWE) concentration values associated with, the first wellhead fluid sample. Correlation data associated with the GWA water analysis data is determined. A second wellhead fluid sample is collected from the petroleum well and only a water conductivity analysis is performed on the second wellhead fluid sample to determine water conductivity data.