Drilling through unconsolidated ground conditions in order to set casing into bedrock is one of the most challenging tasks facing the drilling industry. That is why Numa has spent so much time and energy designing a underreamer systems drill bit that can drill a larger diameter hole than the casing, while simultaneously advancing the casing.
The Super Jaws® Overburden Bit is a revolutionary new bit design with wings that extend out larger in diameter than the casing while in the drilling position. The face design of the Super Jaws® Overburden Bit keeps it almost identical with a conventional bit face, allowing for unmatched penetration rates and smooth operation while drilling through overburden, boulders, or bedrock.
When duplex drilling is completed, the bit is simply lifted off bottom, causing the wings to retract back into the guide body. This allows all tooling to be extracted while leaving the casing in place. There is no forward or reverse rotation required, nor any expensive rings left in the hole.
One version utilizes an inexpensive drive shoe that is welded to the front of the casing. As the bit advances through the formation, the casing is advanced at the same rate due to the drive shoulder on the guide body contacting the drive shoe welded to the casing.
The second version is called Super Jaws® ND, which stands for “No Drive” shoulder. This version utilizes thick wall casing or thick wall threaded casing. The guide body has no drive shoulder on it and the casing is advanced via a casing hammer, duplex diverter, or dual rotary. This version is especially popular in micro-piling and tie-back work where the casing is recovered, or in deep overburden areas where high amounts of friction build up on the outside of the casing.
The Super Jaws® Overburden Bit produces outstanding results in all formations. It is available for drilling hole sizes from 5-1/2″ – 42″ (140 – 1067 mm) in diameter, and can be used with different casing wall thicknesses.