The change in pressure of a fluid column per unit of true vertical depth.
Normal hydrostatic pressure gradient of popular petroleum fluids at Standard Conditions
| Fluid | Normal density range (g/cc) | Gradient range (psi/ft) |
|---|---|---|
| Natural Gas | 0.007 – 0.30 | 0.003 – 1.130 |
| Gas Condensate | 0.200 – 0.40 | 0.090 – 0.174 |
| Oil | 0.400 – 1.12 | 0.174 – 0.486 |
| Water | 1.000 – 1.15 | 0.433 – 0.500 |