Nov 16 2017
Case Study - Traction Drill Collars Reduce Stick / Slip
Two 7” Traction Drill Collars (TDC) were run in a Rotary Steerable Assembly as a trial to improve weight transfer to the bit, and also to reduce vibration & Stick / Slip within the BHA. The 8 ½” section goal was to drill from the 9 5/8” casing shoe at 9,820’, building from 78° to horizontal, before initiating an 87° left turn, whilst holding horizontal to section TD at 16,569’. A new M222 PDC bit was utilised, consistent with the offset wells.
The 6,740’ section was successfully drilled in 96.7 hours, with a drilling ROP of 69.6ft/hr. Offset ROP’s varied between 57ft/hr to 78ft/hr. A significant reduction in Stick / Slip was measured at the LWD tool, with severe Stick / Slip held below 2% for the entire section. The best offset run had measured Severe Stick / Slip, with intervals in excess of 30 minutes, for 20% of the 8 ½” section. Bit grading revealed Worn Cutters on the TDC assembly bit, compared to chipped teeth witnessed on the offset runs; suggesting improved consistent WOB.