− | | Calculate and plot hydrostatic pressures for a depth above and a depth below the zone of interest. Use the rule-of-thumb pressure gradient for that zone. If it is not available, calculate the gradient from the water density using [[Formation water density|density measured from the formation water]] or calculated from the formation water resistivity (R<sub>w</sub>) . For help, see the following sections. | + | | Calculate and plot hydrostatic pressures for a depth above and a depth below the zone of interest. Use the rule-of-thumb pressure gradient for that zone. If it is not available, calculate the gradient from the water density using [[Formation water density|density measured from the formation water]] or calculated from the [[Spontaneous potential logs in water resistivity calculation|water resistivity (R<sub>w</sub>)]] . For help, see the following sections. |