All formation tops intersected by the wellpath can be entered on the Formations tab.  It is only required to input the MD Top value (Measured Depth of the formation top).  All other fields (TVD Top, MD Bottom and TVD Bottom) are calculated from the survey data entered on the Surveys tab when the data is calculated.  Before calculating the formation data, it may be useful to check that all the survey data is up to date beyond the last formation top.  If such data is not available, depths will be calculated by doing a straight-line extrapolation from the last survey station available.

 

As a matter of tracking, it may be useful to record the prognosed formation depths.  These are input by the expected TVD (TVD Prognosed). The other fields (MD Prognosed, TVD Difference and MD Difference) are calculated from the wellplan data.

 

From WellRep version 2.5.1, it is possible to enter formations that are prognosed only (i.e. not drilled yet).  Previously, a value for MD Top (actual top depth) was mandatory.  This has been changed so that either a value for MD Top or for TVD Prognosed is mandatory.  Of course it is possible to have a depth both fields, as long as at least one is not blank.  This makes it possible to enter all prognosed formations and enter the top depth when a formation is actually drilled.

In the above screenshot, two formations that have not been encountered (yet), can be seen:

1.  The 'Clay, Shale' of the 'North Sea' was prognosed at 510m TVD but never encountered
2.  The 'Vlieland' of the 'Rijnland' was not encountered yet but is still expected (the 'Rijnland' 'Holland' extends to the current TD).

 

Prior to printing reports for a Final Well Report and/or to ensure all data is calculated in the correct sequence, ensure all data is entered and then calculate the entire well in one pass as described.