American Oil and Gas Reporter - September 2022 - 75

SpecialReport: Extended Reach Tech
One of the bottlenecks limiting well
economics in many plays is drilling the
vertical section, where bits must endure
potentially damaging torque spikes generated
by sudden formation changes,
notes Brady Walters, the vice president of
engineering for Ulterra Drilling Technologies
LP. To extend bit life in these
applications, he says Ulterra has invented
a novel PDC cutting structure that is delivering
exciting results.
" Across 775 runs and almost 3.5 million
feet drilled, we are seeing ROP increases
averaging between 15% and 23%, "
Walters reports. " This improvement in performance
comes because the wave-like
cutting structure minimizes vibration,
wasted energy and drilling dysfunctions. "
According to Walters, the cutting
structure mitigates these issues by varying
the blades' shape. " Instead of making
every blade straight or slightly curved,
we give every single blade on the bit a
unique shape that has been engineered so
that each cutter will engage the formation
in a distinct way. For example, the third
cutter on one blade will interact with the
rock differently than the third cutter on
the other blades, " he outlines.
" We are trying to let the bit step
through imperfections or changes in the
rock one cutter at a time, with each
blade disrupting and breaking up the
pattern of the blade in front of or behind
it, " Walters continues. " This leads to
smoother drilling than biting into the
imperfection simultaneously, which can
spike reactionary forces that transmit up
the drill string as vibration and potentially
create resonance. "
Staggering when and how cutters contact
downhole imperfections turns those
spikes into gentle bumps and concentrates
the energy that normally would
cause vibration to instead cut rock, Walters
contrasts. He notes that the concept
for the cutting structure originates with a
design engineer named Spencer Case.
" He came up with the idea while watching
YouTube videos of recycling shredders
cutting through tires and other
objects, " Walters recounts. " The shredders'
teeth are spaced so they each engage
the tire individually, allowing the
machine to shred tire after tire without
locking up. "
Since pioneering the concept, Walters
says Case and other Ulterra engineers
have applied it to 27 bit designs. " Most
of these bits fall between 77
⁄8 and 121
⁄4
inches in diameter and are used to drill
intermediate sections and gentle tangents
where bits often fail. For example, many
of our runs are in vertical sections of the
Delaware Basin, " he says.
" The data from the runs shows that we
are getting higher ROP for the same
weight on bit with an otherwise comparable
design, " he reports. " Today, we are
beginning to test the new concept in laterals,
where the more efficient cutting
structure has shown an aptitude for improving
directional responsiveness and
predictability that enables increased ROP
and run length. "
Accelerating Engineering
Applying the new cutting structure to
proven designs takes careful engineering,
Walters comments. " We need to lay out
the waves to minimize spots in the cutting
structure where two blades may behave
the same so we can introduce as
much disruption as possible in the bladeto-rock
interaction, " he explains.
To aid its engineers, Walters says Ulterra
is improving the tools they use. " One
of the most frustrating parts of engineering
is inputting an idea and then waiting
30 seconds for computer feedback, " he reflects.
" It's much easier to stay in engineering
mode when we barely notice
delays, so we are optimizing our software's
code to get more from multithreading
and other processor improvements. "
For particularly demanding tasks,
such as computational fluid analysis, Ulterra
is moving calculations from engineers'
computers to the cloud, Walters
adds. " When engineers want to check
how a particular nozzle layout will affect
performance, which can take 10 or 15
minutes to calculate, they can leave the
number crunching to the cloud and work
on other tasks until the results are ready, "
he explains.
Walters points out that a commission
is updating the International Association
of Drilling Contractors' standard for dull
grades. " The new standard breaks the bit
into zones-cone, nose, shoulder and
gage-to provide more resolution than the
existing system, which only classifies
cutters as inner or outer, " he says. " The
standard also calls for quantifying the
percentage of diamond loss on each cutter,
which should help the industry diagnose
and improve bits even faster. "
Walters predicts that the more precise
dull grades predominantly will be generated
using artificial intelligence. " Ulterra
and other companies are developing mobile
applications that can analyze photos
of dull bits to grade them, " he mentions.
" The goal is to let people in the field take
photos at about the same pace as they do
today, but get back a more useful report. "
For the more precise data to speed
drilling improvements, Walters stresses
that it must be easy to find and interpret.
" For the industry to move forward as
quickly as possible, we need to develop
data transfer standards so operators and
service companies can import dull
grades and other information into internal
tools and match them with well
headers, " he clarifies.
Some companies already are well
down that path, Walters praises. " It is
powerful to see drillers with tools that
allow them to check dull photos, other bit
details and directional data from offsets
without doing any manual research or
Standard
New Concept
By varying each blade's shape, a new cutting structure concept from Ulterra Drilling
Technologies LP enables PDC bits to engage the formation one cutter at a time.
According to the company, this approach minimizes reactive torque and drilling dysfunctions,
enabling bits to drill faster and longer.
SEPTEMBER 2022 75

American Oil and Gas Reporter - September 2022

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