Using caliper logs to interpret breakouts

Caliper tools are commonly run to obtain information about the formation(s) being drilled, e.g. strike and dip of bedding, and to estimate the volume of cement required for casing. You can however, use unprocessed oriented caliper logs to interpret borehole breakouts. The logs needed for this interpretation are:

• Azimuth of Pad 1 (P1AZ) relative to magnetic north
• Diameter of the borehole in two orthogonal directions (C1 between pad 1 and 3, C2 between pad 2 and 4)
• Borehole deviation (DEVI) from the vertical
• Azimuth of borehole drift (HAZI)
• Bearing of pad 1 relative to the high side of the hole (RB)

To interpret breakouts, Depth, C1, C2 and DEVI must be available. Only two of the P1AZ, RB and HAZI are necessary as the missing log can be calculated using the following equation: