Operations Manual
Reaming and Circulating Back reaming for extended periods with the D-Tech RST is not recommended. If back reaming is necessary, ensure that flowrate is kept at or above the minimum flow for the tool size and as low as practically possible, and Bit RPM is at least 40 but kept low to reduce shock and vibration. It is often necessary to ream small sections while running in the hole. For longer sections of reaming such as a curve that was drilled with a conventional BHA, we suggest a separate, stabilized reaming run without D-Tech RST. • Reduce flow to the RSTs Minimum Flow rate (see Appendix A) and bit RPM of 40, attempt to wash to bottom . This will reduce piston pressure significantly but will allow the RST to ream with minimal vibration. • Monitor MWD shock, vibration and annular pressure readings if available. • If weight begins stacking while washing to bottom, top drive or rotary should be increased to 60 RPM. • Slowly increase both the GPM and rotary or top drive RPM as needed. • Hole conditions should dictate reaming ROP. Example (RST675 – minimum flow 400 GPM) 1. Trip in hole without washing or reaming if possible. 2.When reaming becomes necessary wash with 400 GPM, and bit RPM of 40. 3. If the rig begins to stack weight while washing, increase bit RPM. 4. If weight stack does not subside increase GPM to 450 and bit RPM to 50 RPM. 5. If weight stack does not subside increase GPM to 475 and bit RPM to 60 RPM. 6. If weight stack does not subside increase GPM to 500 and bit RPM to 70 RPM.
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