Adjust reference elevation

A well schematic may sometimes need to be adjusted to a new rotary table elevation, for example when planning a plug and abandonment project. In these cases, it is preferable to prepare the schematic against the original rotary table elevation, because the available source data, such as end-of-well reports, is typically based on that reference. Preparing the schematic directly against the new elevation would require each depth to be adjusted manually during input, which is time-consuming. This becomes even more challenging when the actual elevation at the start of the well differs from the elevation used during the planning phase and the schematics must be updated quickly.

WellSketch provides options to quickly adjust well columns to a different reference elevation. This allows users to prepare all columns using the available data and then adjust them efficiently to the new elevation. This can be done in two ways:

•The first and preferred method is to apply the adjustment through the trajectory, either the survey or the well plan. This updates the survey data by adjusting all measured depths (MDs) and recalculating the trajectory, including true vertical depths (TVDs). It also updates all well columns associated with that trajectory, meaning any column that references it. This approach is preferred because it keeps related data, such as the well schematic, formations, and graphs, consistent with the selected reference elevation. If a specific column must not be adjusted, it should not reference the trajectory being adjusted.

	Current elevation
	The current reference elevation. Typically this is the rotary table elevation for the trajectory selected under 3 below.

	New elevation
	The adjusted reference elevation. After committing the value (by clicking another field or pressing Tab), the correction applied to the selected trajectory and associated well columns is shown below.

	Trajectory to adjust
	The trajectory (survey or wellplan) that will be adjusted.

	Associated well columns
	All well columns, associated with the selected trajectory, that will be adjusted so that all survey data and well columns remain at a consistent elevation. If a certain column must be excluded for some reason, the its link to the selected trajectory must be removed. This can be done by editing the column itself or through the Link Columns dialog in the Survey Data menu.

•The second method is to adjust an individual column via the Elevation buttons in the column settings menu. However, this only applies to columns that are not associated with a trajectory. In some cases, the column’s association with a trajectory may therefore need to be removed before applying the adjustment.

Two important points should be noted:

•Because a column can be excluded from the adjustment or adjusted individually, inconsistencies between columns can occur. Since both adjustment methods are available, this cannot be fully prevented by the program. Users should therefore apply these options carefully.

•For WellSketch to process depth calculations correctly, the trajectory must include an initial survey station at measured depth (MD) 0.00. If, after the correction, the first MD is greater than 0.00, WellSketch automatically inserts a survey station at 0.00. If the trajectory is later corrected back to the original elevation, this inserted station becomes the first station with a negative MD (which is acceptable), while the original first station returns to 0.00. This is not corrected automatically, but the station with the negative MD can be deleted manually if required.