Refining your selection

Important   The workflow step Refine Selection is only relevant to thickness maps where at least one event (either top or base) has been assigned the data type 'Marker' on the Assign Data form. If you only use surface data (i.e. a 2D grid or tri-mesh) for both the top and base events, this step is skipped and you continue with the next step in the workflow Interpolate Map.

On the Refine Selection form, you can change the selection of wells to be included in the thickness map calculation:

  1. At the top of the form ensure that the thickness map of interest is selected.

  2. From the Well group drop-down list, select the well group that contains the wells you want to use. The table on the form will only include wells which actually have a marker for the event(s) that you selected in the Assign Data step. For example, if you selected for Top Event the data type 'Marker' and for Base Event the data type 'Surface', only wells which actually have markers for the Top Event will be listed. The table below gives an overview of listed wells in relation to well marker existence for the top and/or base event:

    Top Event set as: Base Event set as: Wells to be listed on Refine Selection form:
    Surface Surface Wells not listed
    Marker Marker Wells which have a marker for the Top Event, as well as for the Base Event
    Marker Surface Wells which have a marker for the Top Event
    Surface Marker Wells which have a marker for the Base Event
    Marker + Surface Marker Wells which have a marker for the Base Event
    Marker Marker + Surface Wells which have a marker for the Top Event
    Marker + Surface Surface Wells which have a marker for the Top Event
    Surface Marker + Surface Wells which have a marker for the Base Event
    Marker + Surface Marker + Surface Wells which have a marker for either the Top Event or the Base Event

    Note that the well list includes wells that are located outside the selected Area. The 'TVT' and/or 'TST' column shows the thickness at the marker location or, when two markers are used, at marker midpoint.

    If a wellbore is highly deviated, the top marker may be below the base marker. This means that a simple thickness calculation based on TVDSS difference will not be reliable. In this case, the TVT and/or TST column shows a warning icon.
  3. If the thickness could not be calculated, or when an apparent thickness is calculated (see Thickness map missing marker for more on this) the wellbore is unchecked for use, and it is indicated by a warning icon. You can decide to use the location by manually entering an anticipated thickness value at the marker location (this will automatically check the wellbore checkbox). When you manually enter a value, the Edited by column updates with the name of the user who made the edit. After clicking Apply or OK, the changes are saved and reflected in the Thickness/Trend Map.
  4. The Exclude marker picks with well angle below checkbox is unchecked by default. When you check it, you can specify an angle that refers to the smallest angle between a wellbore and a marker. Enter the angle below which markers should not be used in the calculations.
  5. Uncheck the wellbores you do not want to include in the calculations.
    6. Important   If you are using the marker-marker combination, but you do not have dip/dip azimuth information for the markers, it is recommended to interpolate one of the two marker events first, then use the interpolated surface (2D grid or tri-mesh) as input to the thickness map calculation. For more on this, see Assigning data to a thickness map.
  6. Click Apply to save your changes and keep the form open, or click OK to save your changes and go to the next from in the workflow, Interpolating thickness maps. After clicking Apply or OK, the Thickness/Trend Map is updated, and will only display the wells that are selected.
Note that wellbores which penetrate an event several times may have multiple marker picks for the same event. In this case the wellbore name will occur multiple times in the Wellbore column.

After making changes to any of the selections on the form, or after changing the position of a marker, you must click the Calculate button to recalculate the thickness.