American Oil and Gas Reporter - April 2016 - 85

SpecialReport: Drill Bits & BHAs
a 419 Pexus bit. "None of the PDC bits
used in offsets were able to complete the
interval, which contained sand and shale
sequences with low to moderate compressive strength, with a single bit," Beaton
says. "The Pexus SVP419 drilled the entire
interval in one run, and came out in great
condition. At the same time, it achieved
an average ROP of 276 ft/hr, 26 percent
faster than the fastest PDC offset."
Tailored PDC
To push the performance of PDC bits
to the next level in hard and abrasive formations, National Oilwell Varco now
offers Tektonic™ bits. Alexis Garcia,
product line director for performance
series drill bits, says the bits' design benefits from extensive laboratory testing in
facilities designed to replicate dynamic
downhole conditions.
"During development, our engineers
built and tested full-scale bits in the laboratory," he recounts. "The hydraulic
team achieved up to 35 percent ROP increases compared with base-line bits by
improving nozzle orientations and adding
unique flow guides to the bit body structure. The cutter technology team developed
specialized cutter treatments that improved
ROP 150 percent."
After these successful results, Garcia
says the teams expanded to more complex

Because their primary cutting structure
has the smooth torque response and
toughness generally associated with
roller cone bits, Shear Bits' third-generation Pexus™ hybrids can employ aggressive, speed-boosting designs without
compromising durability or steerability.

By combining application-specific designs with efficient hydraulics and ROP-boosting cutter
coatings, National Oilwell Varco's
Tektonic™ bits are delivering exceptional performance in challenging wells.

geological structures, complicated well
profiles, and various BHAs. "By combining extensive dynamic drill bit modeling
and improved hydraulics with a strong
focus on the bits' true failure mechanisms
for each application, we were able to
verify that improvements in both body
and cutter technology would yield breakthrough performance," he reports.
While a strong technological foundation
is vital, Garcia says tailoring a bit to specific applications can yield remarkable
improvements in ROP without sacrificing
borehole quality. "For example, in the
Eagle Ford, we were asked to drill a
12¼-inch surface interval in one run at a
high ROP," he recalls. "In response, we
developed a six-bladed bit with 19 millimeter Reflektor™ cutters suited for highimpact drilling. The bit drilled from 125
feet to 3,980 feet in six hours at an
average ROP of 642.5 ft/hr, which was
an ROP field record for the operator."
The bit drilled 59 percent faster than the
best offset and came out of the hole graded
0-0-NO-A-X-I-NO-TD, Garcia details.
"In another Eagle Ford application,
the operator wanted to improve penetration
rates in a 77⁄8-inch intermediate interval,"
he says. "We provided a five-blade bit
with 16 mm cutters that drilled 5,151
feet at an average ROP of 278 ft/hr on a
motor assembly. That is 20 percent faster
than the best offset and 38 percent faster
than the average offset, and the bit came
out in excellent condition."
For the intermediate section in a
Spraberry well in Midland County, Tx.,
NOV designed a seven-bladed, 12¼-inch
Tektonic bit with 16 mm cutters. According
to Garcia, the bit drilled 3,863 feet in
21.5 hours at an ROP of 179.7 ft/hr,
achieving a 101 percent increase in ROP
compared with the nearest offset within
a 10-mile radius of the field. He adds
that the run took 65 percent less time

than the average offset.
"In the Williston Basin, we were tasked
with helping an operator quickly drill a
six-inch lateral with a single BHA,"
Garcia says. "With a five-blade bit with
16 mm cutters and our Agitator™ system,
which reduces friction by oscillating the
drill string, the operator achieved his goal
of drilling from the intermediate casing
shoe to total depth. The bit went 9,446
feet at an average ROP of 145 ft/hr, providing a 39 percent increase in ROP compared with offsets, and set a lateral record
for the operator."
Customized PDCs
GT® Engineering of Shawnee, Ok.,
which has provided roller cone bits for
30 years, has expanded into steel body,
fixed cutter bits. "Like most bit manufacturers, we take pride in tailoring the
bit to a particular field or application,"
comments John Gault, a company engineer. "We always are looking for ways to
save the customer money, such as increasing ROP or reducing torque to minimize damage."
For the past two years, Gault says GT
Engineering has marketed its PDC bits
in Oklahoma and Kansas. "Since we are
new to PDC bits, we wanted to stay close
to home so we could get to a site in a few
hours if we needed to and provide a
quick and timely turnaround on the product," he explains.
"To improve our designs, we try to get
every bit record we can," Gault says. "However, the record by itself will not give us
the full picture of how a bit performed. We
spend a lot of time talking with people on
the rig who can tell us whether a bit
chattered or the rig ran rough."
Most of GT Engineering's customers
are independents with two to six rigs,
Gault notes. "The people who run these
companies are as close to day-to-day opAPRIL 2016 85

American Oil and Gas Reporter - April 2016

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