Evaluating Changes in Water Chemistry Exercise

In a basin containing numerous gas wells, a petrophysicist and reservoir engineer have determined downhole water resistivity from drill-stem tests and produced water samples and calculated apparent water resistivity from wireline logs. The resistivity data have been normalized at datum depth, accounting for pressure and temperature changes. The samples have been taken from the same genetic stratigraphic unit. Additionally, one sample has undergone chemistry analyses, and the information has been plotted on a stiff diagram (fig. 3 below).

Figure 3.

All of these data have been compiled and plotted onto a regional map used in the following exercise.