Establish A Bottom Hole Pattern
- Rotate the bit and circulate mud when approaching bottom. This will prevent plugged nozzles and clear out fill.
- Lightly tag bottom with low RPM.
- Gradually increase RPM.
- Gradually increase weight.
USE A DRILL-OFF TEST TO SELECT BEST WEIGHT AND RPM (WR)
- Select RPM.
- Select bit weight. Depending on bit selected, refer to appropriate page and chart in this catalog for recommended maximum RPM's and weights.
- Lock brake.
- Record drill-off time for 5,000 lb, increments of weight indicator decrease.
- Repeat this procedure for different RPM.
- Drill at weight and RPM giving fastest drill-of time.
THE BIT ISN'T ALWAYS TO BLAME FOR LOW RATE OF PENETRATION
- Mud weight may be too high with respect to formation pressure.
- Mud solids may need to be controlled.
- Pump pressure or pump volume may be too low.
- Formation hardness may have increased.
- RPM and weight may not be the best for bit type and formation — use drill-off test.
- Bit not stabilized.
- The bit used may be too hard for the formation.
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