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One of the most important results is the graph of Surface Weight plotted against Depth.

This graph shows how the surface weight is expected to change with depth. In a vertical well the weight will usually increase linearly (except for a tapered drill string, for example), but in a deviated well the variation can be highly complex, especially when there is a toolstring or BHA passing around a tight dogleg. Note that there is a significant difference between conditions going in (RIH) vs coming out (POOH).

You can also plot the weak point and cable breaking strength on the same plot. You must ensure that the normal running weights (the blue and green curves) are well below the cable or pipe breaking strength (otherwise it will break under its own weight) and that the weak point is chosen so as to be well above the running weight (so that overpull is available if needed) but less than the breaking strength (so it fails before the cable or pipe does). In the following example, the 3000lb weak point choice is too conservative – the overpull (separation between green and light blue lines) is much smaller than it needs to be.

If there is a problem, an arrow and explanatory text will indicate the problem depth.

All of these graphs can be printed, and also cut and pasted into other Windows applications such as Word and Excel.

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