The water gradient is dependent on the density of the water that in turn depends on the total dissolved solids (TDS). A linear equation gives the density as a function of TDS (measured in parts per million [ppm]), reservoir temperature, and pressure. A straightforward conversion changes water density with unit’s pounds per cubic foot to pounds per square inch per foot.

In a normally pressured reservoir the gas-water contact is at the depth where the water gradient pressure and the gas-gradient pressure are equal. This is where the water-pressure line and the gas-pressure line intersect on a pressure-vs.-depth plot.

Answers:

1. 165 degrees F
2. 0.432 psi/ft
3. 0.07123 psi/ft
4. 7,981 ft