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drilling performance. DSE is calculated using both surface and downhole data. The results are used to compare DSE with the
rock compressive strength at surface and downhole conditions. The rock compressive strengths (UCS and CCS) are
calculated from the well logs.
Fig. 16 shows the surface and downhole drilling parameters (ROP, WOB, RPM, torque and HSI). ROP varies from 5 ft/hr
to 60 ft/hr depending on the rock type being drilled (sand or shale). Torque and WOB are the parameters with different
surface and downhole values. This can be explained because of the friction generated by rotating the drilling string inside the
hole. The RPM values are almost the same for the surface and downhole conditions, except when a mud motor is run from
12,195 ft to 13,195 ft.
Fig. 17 shows DSE calculated with the surface parameters and the rock strength (UCS) vs. depth. There is no correlation
between the surface DSE and the UCS. The surface DSE is too high.
Fig. 18 shows DSE calculated with downhole data and the rock strength (CCS) vs. depth, again. In t...
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- Spring '13