WellTest Wizard: Adjust Gauge Pressure to Datum Depth

All of the equations and plots used in pressure transient analysis are developed for analyzing sandface pressures. As a result, when preparing wellhead pressures for analysis we calculate sandface pressures. Similarly, when preparing downhole gauge data for analysis, we apply an adjustment to convert the run depth pressures to sandface conditions, and this dialog box facilitates the adjustment.

• The pressure adjustment can be entered manually.
• Or, the pressure adjustment can be calculated based on gauge depth, datum depth, and fluid gradient.

The pressure adjustment accounts for the hydrostatic head between the gauge depth and datum depth. As a result, true vertical depth (TVD) should be used for gauge and datum depths when calculating the pressure adjustment. If the gauge depth is below the datum depth, the adjustment will be negative.

Pressure adjustment = ( Datum Depth (TVD) – Gauge Depth (TVD) ) * Fluid Gradient