Rapid analysis and recommendations result in significantly prolonged bit life and improved drilling performanceDownload PDF
Abrasive wear and gauge/shoulder damage
The Woodford Shale
An operator experienced premature polycrystalline diamond cutter (PDC) bit failure while drilling hard, extremely abrasive shale, requiring 35+ runs per lateral section. To address this downhole failure and determine the origin of the bit damage and suspected dysfunction, Halliburton deployed Cerebro Force™ In Bit Sensing technology for multiple runs across multiple wells in this formation. High-frequency downhole and surface data was combined with forensic bit and BHA images to identify and rectify drill string buckling, rate of penetration (ROP) loss attributed to the use of rotating control devices (RCDs), and WOB and differential pressure (DIFP) tare inconsistencies. Additionally, a team-based, continuous improvement process was implemented to evaluate the root cause of the downhole dysfunction and recommend bit/BHA design and operating procedural changes before the next bit was on bottom. This rapid analysis and joint recommendation process significantly prolonged bit life and improved drilling performance for the operator.
The primary cause of the PDC bit failure was smooth wear and thermal damage. The wear flats were attributed to abrasion and mechanical chipping that rapidly progressed to thermal damage. Higher weights were ineffective, and it was hypothesized that buckling was occurring, causing insufficient weight transfer and increased lateral vibration.
Cerebro Force in bit sensors were run in hole (RIH) during four runs to measure weight, torque, revolutions per minute (RPMs), and lateral, axial, and torsional vibration to evaluate weight transfer issues and dysfunction.
High frequency downhole and surface data were combined with forensic images of the bit and BHA to confirm the weight transfer matters. In total, three major problems were identified and resolved—drillstring buckling, ROP loss caused by RCDs, and WOB and DIFP tare inconsistencies.
During early runs, drill string buckling resulted in the downhole WOB being much less than surface WOB (DWOB<<SWOB). To correct this, heavyweight drill pipe (HWDP) was run across the buckling zone. Subsequent runs showed significant improvement to DWOB, reduced lateral bit vibration, and improved performance and dull condition.
Significantly decreased DWOB, DIFP, and ROP were noted when running tool joints
through the RCD. Although observed previously, in-bit accelerometers showed increased lateral vibration resulting from ROP loss, which continued long after the ROP recovered.
DWOB and downhole torque (DTOR) were often much higher than SWOB and DIFP (converted to torque). Plots of hookload and standpipe pressure tare values were used as indicators of inconsistent tares. Although premature motor failure was not observed during these runs, premature PDC cutter failure was observed.
High-frequency in bit load sensing helped identify persistent lateral vibration after an ROP loss event attributed to tool joints interacting with RCDs. A team based, continuous improvement process was implemented by Halliburton to evaluate the root cause of the downhole dysfunction and recommend bit/BHA design and operating procedural changes to the operator before the next bit was on bottom. This rapid analysis and joint recommendation process significantly prolonged bit life and improved drilling performance.