American Oil and Gas Reporter - April 2016 - 84

Atlas Copco Deep Leached Dark Matter™ cutter

Premium USA Made Nonleached Cutter

50 passes VTL

100 passes VTL

150 passes VTL

A head-to-head test on a vertical turret lathe shows that Atlas Copco's Dark Matter™
cutters (left) can outlast even premium, U.S.-made deep leach cutters (right). The ultratough cutters work with a unique blade geometry to give the company's Commander™
PDC series bits fantastic durability.

would function under a variety of drilling
challenges. "We saw as much as a 35
percent improvement in stability in offcenter-axis drilling situations, and a 29
percent improvement in stability for abnormal force absorption," he reports.
The new bits are available in gauge
lengths from 15⁄8 inches to 43⁄4 inches.
"Many drillers like a shorter gauge length,
because shorter bits are more responsive
to steering for increasing build rates.
However, others prefer the drilling stability
and hole quality provided by longer
gauges. The trend seems to be toward
shorter gauge lengths, but enough people
favor longer ones for rotary steerables
that we wanted to cover both ends of the
spectrum," explains Atlas Copco Applications Engineer Jason Palmer.
84 THE AMERICAN OIL & GAS REPORTER

Johnson says Dark Matter cutters benefit from a deep leaching process that removes cobalt. He points out that cobalt
is the key catalyst used during the manufacturing process to create the diamondto-diamond bonds of a PDC cutter, and
join the diamond layer to a tungsten carbide substrate so the cutter can be brazed
to the bit's body.
However, Johnson says cobalt decreases
thermal stability. "The cobalt that remains
in the diamond layer from the sintering
process expands in response to heat at a
different rate than the bonded diamond,"
he explains. "Eventually, the cobalt's expansion can cause diamond-to-diamond
bonds to break, leaving drillers with a
cutter that will not drill.
"To keep that from happening, in Dark

Matter cutters, the cobalt is removed from
the top 400-800 microns of the cutter
surface area, and significantly deeper from
around the outer edge, where the cutters
experience the highest temperatures while
drilling," Johnson says. "Tests on a vertical
turret lathe show this makes a huge difference in cutter durability."
Fast Hybrid
The latest iteration of Shear Bits'
Pexus™ hybrid bits is geared toward a
new application. "Because Pexus bits
combine the speed and durability of a
PDC bit with the toughness and directional
control of a roller cone, the first and
second generations targeted applications
that traditionally required both roller cone
and PDC bits," says Tim Beaton, the
company's vice president of engineering
and manufacturing. "In contrast, the third
generation targets applications that traditionally have required only PDC bits."
The hybrid bits have two cutting structures, Beaton notes. "The primary cutting
structure gouges the rock, while the secondary cutting structure shears it," he
describes. "The primary structure is free
to rotate during drilling, so the bits have
the smooth torque response typical of a
roller cone bit. With the secondary structure, they also deliver faster ROP."
With no seals and bearings, the bits
are capable of longer runs than roller
cone designs, Beaton adds. He describes
the bits as proven, noting that in the three
years since their introduction, the first
and second generations have completed
hundreds of runs and achieved top performance in many applications. "In 2014
and 2015, we set at least 22 world records
for hybrid bits," he reports.
The Pexus bits for PDC applications
generally have fewer blades and cutters
than a PDC bit, Beaton says. "The lower
blade and cutter count allows the bit to
be more aggressive," he explains. "On a
typical PDC, this speed would come at
the cost of tool-face control and durability,
but on the hybrid, we can reduce the
blade count while maintaining reliable
durability and a smooth drilling response.
As a result, the bit can drill faster than
conventional PDCs while drilling as far
and much more smoothly than other
fixed-blade drill bits."
According to Beaton, the third-generation Pexus bits have completed more
than 25 runs in Western Canada. "The
results have been spectacular," he assures.
"In fact, based on data for 2015, we are
continuing to set world records for ROP
with hybrid bits."
For a 12¼-inch hole application where
PDC bits ranging in type from a 616 to
519 had been utilized, Shear Bits developed

American Oil and Gas Reporter - April 2016

Table of Contents for the Digital Edition of American Oil and Gas Reporter - April 2016