American Oil and Gas Reporter - April 2018 - 133

SPECIAL REPORT: DRILLING TECHNOLOGY

Latest Bit Designs Drill Faster, Farther
By Colter Cookson

Human beings are exploring deep
space, eradicating diseases, designing pilotless planes and cars, and placing horizontal wells with multi-mile laterals on
target. Psychologists say we do so much
in part because we all share a desire to
accomplish big things. For the humans
in the oil and gas industry, that means
celebrating even their greatest successes
for only a few days, then getting to work
on the next challenge.
Nowhere could that dynamic be more
obvious than in the world of drill bits.
Instead of resting after record-setting
runs, bit engineers analyze their designs'
performance to identify and address the
barriers that keep them from drilling even
faster and farther.
Their efforts are paying off. PDC makers say their latest designs deliver significant improvements in speed and durability
by optimizing hydraulics, enhancing backup cutters, leveraging modern motors,
and minimizing reactive torque. Meanwhile, the newest roller cone and hybrid
bits employ advanced cutters and application-specific cutter configurations to
set new standards for drilling efficiency
and durability.
To drill faster, bits need to handle
the additional cuttings generated by the
extra speed, notes Chris Casad, innovation
project manager at Ulterra. "As better
PDC bits have unlocked faster penetration
rates, it has become clear we need to
take the next step in hydraulic performance," he says. "Improving cuttings evacuation not only enables faster rates of
penetration, but also keeps the cutters
clean and cool. This minimizes thermal
degradation and cutter damage, enabling
the bits to maintain their high performance longer."
According to Casad, Ulterra has advanced hydraulic performance through a
new concept called SplitBlade™. The
primary blades in SplitBlade bits are divided into two parts, with the inner part
offset from the outer part near the shoulder.
"The offset creates a recess to put a
second nozzle for each blade," he explains.
"Two nozzles create dedicated flow paths
from the cone of the bit and from the
shoulder outward. The focused flows en-

ergize the cuttings and ensure evacuation
happens quickly and reliably.
"In addition, offsetting the blades gives
bit designers the opportunity to try cutting
structures that previously would have
been impossible," he comments. "For example, because the offset increases the
distance between the cutters, we often
can double the diamond volume in areas
that are seeing a lot of wear without encroaching on an adjacent cutter."
Casad adds that the offset gives the
bit more points of contact with the formation, allowing it to distribute point
loads more evenly and reduce torque
fluctuations. He says the smoother torque
improves tool face control, cutting the
amount of time spent sliding in the curve
and enabling the bit to stay on target
once it is in the lateral.
He highlights one other benefit: Because they are so clean, SplitBlade bits
do a great job of converting weight into
energy. "Like a knife, a PDC bit works
by applying force to a small area," Casad
notes. "When cuttings are recirculating
or building up on the tool face, they
spread the weight across a wider area,
making the cutters less effective."

By applying more weight to the bit,
Casad says drillers can increase depth of
cut to improve performance. "Fast rotation
speeds and a low depth of cut cause the
bit to turn and start eating into the well
bore, creating bumps and undulations. A
high weight and a lower rpm let the bit
drill fast, clean and smooth, meaning the
wellbore will be easier to complete and
produce," he says.
The SplitBlade concept has been tested
on more than 300 runs and has drilled
more than 2 million feet across North
America and in China, Australia and
South America, Casad reports.
"The field testing started in the Eagle
Ford, where operators were looking for
ways to drill 15,000 feet through the
curve and lateral sections without steerability issues in the curve or tracking
issues in the lateral," he relates. "When
we introduced SplitBlade, we were able
to combine the sections more reliably
while cutting drilling times by 30 percent.
The bits came out with a dull grade of 11 to total depth and drilled smoothly
through both sections."
While it is often used in curve and
lateral bits, Casad says the enhanced hy-

With two nozzles for each blade,
the cutters on Ulterra's SplitBlade™ bits stay clean, cool and
sharp. The company adds that
the two-part blades have more
points of contact with the formation, which improves tool face
control by mitigating torque ﬂuctuations.

APRIL 2018 133

American Oil and Gas Reporter - April 2018

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