) button to add a row to the Frac Gradient spreadsheet and complete the information for each TVD.Frac Gradient Section
Well Planning Report
The Frac Gradient section uses a spreadsheet to define the fracture gradient profile as a function of true vertical depth.
The Current Wellbore/Design picklist identifies the active wellbore/design for the data displayed in this section.
This section displays information for the wellbore/sidetrack selected in the Current Wellbore/Design picklist. Changing the selected wellbore/sidetrack updates the information displayed in the section.
Note: This section is read-only when the associated Design is locked or another application has the Design open.
For information on using spreadsheets, see the Using Spreadsheets and Tables topic.
Note: This section is read-only when the associated Design is locked or another application has the Design open.
To enter data in the Frac Gradient spreadsheet
Click the Add Row () button to add a row to the Frac Gradient spreadsheet and complete the information for each TVD.
The first row in the spreadsheet is calculated by OpenWells® software and is read-only. The first layer (top) must be specified at ground level (for land wells) or mud line (for offshore wells). The default value is calculated as follows:
For land wells: Earth starts at Elevation (ft) - Ground Level
For offshore wells: Earth starts at Elevation (ft) + Water Depth (ft)
The Fracture Pressure and Overburden Pressure fields are read-only for the first row only. Fracture pressure is calculated as follows:
For land wells: Default Pressure (psi) = 0 (psi)
For offshore wells: Default Pressure (psi) = (Water Depth (ft) + Air Gap)* 9.00(ppg) * 0.051948 (API units)
TVD
The TVD field specifies the vertical depth to the top of the layer. This layer is used for well TD if well TD is deeper than the last specified layer.
Fracture Pressure
Entering a value in the Fracture Pressure cell automatically calculates the value in the Equivalent Mud Weight (EMW) cell. Changing the value in the EMW cell recalculates the Fracture Pressure. Fracture pressure is calculated using the following logic:
For land and offshore wells (if not the first row in the spreadsheet):
Pressure (psi) = Vertical Depth (ft) * EMW (ppg) * 0.051948 (for API units)
Note: If you clear the Fracture Pressure, the corresponding EMW will also be cleared.
EMW
Enter an equivalent mud weight (EMW) fracture pressure gradient for each TVD. Entering or changing the EMW causes the Fracture Pressure to be automatically re-calculated.
EMW is calculated for both land and offshore wells as follows:
For the first row: Default EMW (ppg) = 9.00 (ppg).
For all other rows: EMW (ppg) = Pressure (psi) / (Vertical Depth (ft) * 0.051948)
Locked check box
The Locked check box appears at the bottom of the Frac Gradient section. This check box indicates whether the associated Design has been locked. If activated, the Design is locked and data in the section can no longer be modified. A Design can be locked or unlocked through the Design Properties dialog accessed through the Engineer's Desktop™ applications, such as PROFILE™, COMPASS™, CasingSeat™ and StressCheck™.
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