Calculating Sandface Pressures

All of the equations used in the analysis are developed assuming that pressures are referenced at sandface conditions. As a result, if your data includes wellhead pressures, they must be converted to sandface pressures.

Use this procedure to convert wellhead pressures to sandface pressures:

1. Click the Production Editor tab.

2. Ensure that you have values in either the Tubing Pressure or Casing Pressure columns of the table.

3. If appropriate, specify liquid levels in the Liquid Level column of the table. Static oil and water gradients may be entered in the Oil and Water Gradient columns. Alternatively, you can opt to calculate these gradients by clicking the Calc checkbox in the header of the Oil and Water Gradient columns.

If you do not see these columns on the table, see Grid Options.

4. Click the Calc SFP icon (). A dialog box opens.

5. In the Wellbore Data tab within the Wellbore Calculations dialog box, modify the inputs to the wellbore calculations. You must fill out the following sections:

  • mid-point of perforations (MPP)
  • tubing specifications (if your pressure source is tubing pressure)
  • casing specifications

6. If you are dealing with more than one phase, click the Pressure Loss Correlation tab and select the most appropriate correlation.

7. If the well is deviated, click the Deviation Survey tab. This table can be populated manually, or by copying and pasting from the deviation survey.

8. After you have entered all the necessary information, click Calculate.

The calculated values are displayed in the Calculated Sandface Pressure column of the table. These are the pressures used for analysis.