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Figure 110: Example well plan graph.
The planned dogleg severity should have consisted of a short 2 deg/100 nudge and drop then a simple 2deg/100 build to 27 degrees inclination then a hold to TD. The actual inclination against md graph is plotted in figure 110:
Figure 111: Actual inclination against measured depth graph.
Clearly things did not go according to plan. However, the directional driller used a standard technique for the drop section of the nudge by replacing a motor (smooth build) with a pendulum rotary assembly (slow natural drop) which is an acceptable and economic method of returning to vertical. On closer examination, the build section is rapid at first then slower later. This is likely to be an assembly with a bent sub above the motor which is less aggressive at higher inclinations but assembly was capable of over 5 degrees of dls when only 2 was needed, suggesting a slide ratio of less than 40%. This explains the rapid changes in dls in the build section but even that is not unusual. The main problems here lie in the hold section where the directional driller has great trouble holding inclination and tends to steer a great d l n n mp o pl c h su ys ‘on h l n ’. H s over correcting and creating unnecessary doglegs when a smpl ‘ m h g fomwh you ’ pp o ch would h c d smooh w llp h.
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