Statoil Improves Lateral Stability in Shale Horizontal Section Using PDC Bit with Central Stinger Element

Extend bit life with Stinger element

Smith Bits, a Schlumberger company, used the IDEAS integrated drillbit design platform to configure a customized bit that included a centrally located Stinger conical diamond element. The Stinger element is manufactured from synthetic diamond material that provides improved impact strength and resistance to abrasive wear.

The element was positioned at the center of a six-bladed bit by selectively removing conventional cutters, creating a void that allows a small rock core to develop at the bit's central axis. When the bit's void area locks onto the rock core, stability of the entire BHA is dramatically improved, and vibration is reduced.

Increase BHA stability and reduce trips

A study was conducted using actual downhole MWD and LWD data to determine if a PDC bit with a central Stinger element provides increased lateral stability compared with a conventional bit. To ensure a valid comparison, all runs were performed by Statoil on a similar steerable-motor BHA with equivalent operating parameters. After compiling the data, engineers compared lateral vibration of the baseline 6-in MDi616 bit (13 runs; 885 h) with a 6-in MDiZ616 bit that was equipped with a centrally located Stinger element (2 runs; 209 h). The analysis was conclusive and confirmed that the element-equipped MDiZ616 bit had a higher percentage of drilling hours at lower levels of lateral vibration as well as a lower percentage of hours at high vibration levels. The reduction in vibration resulted in fewer trips for bit and MLWD changeouts, reducing drilling costs.