Result chart

Softdrill NL   


After calculating the Torque & Drag model, the program will display the Result Chart. Initially it will display the tension chart but this may be changed to torque or normal force through the Chart Menu.  When the calculation mode was set to Trip Log, different charts will be shown.  Please see below.


The primary objective of the Torque & Drag calculation will be to ensure that all tension curves are to the right of the buckling curves and to the left of the tension limit line.  This will ensure that buckling will not occur and the tensile limit of the pipe (or its connections) will not be exceeded.


Note that the tension limit line shown is the 100% value, minus Safety Factor and Margin of Overpull.

Tension curves may be hidden temporarily to improve readability by clicking the relevant checkboxes in the legend.


Note that the chart is initially scaled in accordance with the tension curves.  If the maximum tension is substantially lower than the maximum tension, the tension limit curve may not be showing on the chart (off scale).  The same may apply to (part of) the buckling curves.

The scaling of the chart can be manipulated in several ways. Please refer to Scaling charts for more details.

To track the curves and read data at specific depths, the data reader can be used.


The (tension) chart can be right-clicked with the mouse to access the chart menu:



Chart type selection

These three options ([Tension chart], [Torque chart] and [Normal force chart]) allow switching between the tension, torque and normal force chart.  The currently active chart type is indicated by the bullet point in front of the menu item. 


The [Include block weight] option may be used to include block (and topdrive) weight in the tension curve.  A check-mark in front of the menu item indicates whether this is currently included. Note that this option is only enabled when displaying the tension chart after calculating Trip Log Mode.


Show/hide chart legend

Use this option to toggle visibility of the chart legend.


Chart export

The options provide the possibility to copy the chart - as currently shown on screen - to the Windows clipboard.  This is convenient for including the chart in Powerpoint presentations, Word or Excel documents, etc.  Selecting the metafile option may give better results if the pasted image has to be scaled.


The chart may also be saved to an image file (bitmap or metafile).  Click the menu option and select the image type in the Save dialog box displayed.


Print chart

When one of the print options is selected, the graph will be sent directly to the printer.  Page orientation (Landscape or Portrait) is forced by selecting the relevant option.


Chart settings

This option will show the Chart Settings dialog box to allow manipulation of the chart appearance.



The torque chart will be displayed as below.  Chart scaling can be manipulated in exactly the same manner and chart settings are shared with the tension and normal force charts.


Note that the torque limit line shown is the 100% value (normally connection make up torque), minus the Safety Factor.



The third chart type will display normal force along the drill string.


It is very important to note the units for the normal force. The normal force is expressed as the total force over a specified length.  This length is taken as the calculation's step length. As a result, the normal force value changes with a different step length.  This is very important when evaluating casing wear. 

For example: a normal force (contact force) of 3,000 lbs/30m is exactly the same as 1,000 lbs/10m.



Trip log charts


Upon completion of the calculation, the program will - similar to the Single Depth Mode - display a tension chart.

This chart displays the calculated surface tension for bit depths between surface and a particular depth (i.e. the bit depth input value).  Because this chart displays surface tension rather than drill string tension, buckling curves and tension limit lines are not shown.


Depending on whether the block weight was included, this chart will display surface hook-load or indicated string weight.  Which of the two is displayed can be controlled through the [Include block weight] option in the chart menu.



The chart may be changed to display surface torque for bit depths for increasing depths.





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