Compute TST & TVT

The TST and TVT calculation is used to compute actual thickness of a zone by taking into account the regional or local structural dip and azimuth and directional well surveys.

To open the Compute TST & TVT tool, select Compute>From Zones>TST and TVT from the menu bar at the top of the Main Module.

Variables To Compute

Zone - This dropdown selects the zone for the TST and TVD calculation.  Petra will use the upper and lower extents selected on the zone's interval definition.

TST - This dropdown sets the desired zone data item that will contain each well's calculated true stratigraphic thickness.  You can select an existing zone item or enter a new name.

TST - This dropdown sets the desired zone data item that will contain each well's calculated true vertical  thickness.  You can select an existing zone item or enter a new name.

Structural Dip and Azimuth

This section defines the structural dip and azimuth used in the TST and TVT calculation.  The structural setting can either be constant or individually set for each well with zone data items.

Zone Data - This option uses zone data items for dip and azimuth for each well.  Wells without dip or azimuth entries will not have a TST or TVT calculation.

Constant -  This option instead uses a constant, regional dip and azimuth for all wells in the calculation.

Values are Apaprent Dip and Azimuth - This option changes the calculation to use apparent dip and azimuth.  Note this option will use borehole azimuth instead of the bed azimuth for deviated and horizontal wells.