American Oil and Gas Reporter - April 2018 - 139

SPECIAL REPORT: DRILLING TECHNOLOGY
array, we put more of the inserts into
contact with new rock, limiting damage
and increasing cutting efficiency."
Field tests confirm that this spiral configuration reduces damage and improves
ROP, Long says. He indicates the ROP
increase generally exceeds 20 percent,
but can exceed 50 percent in the right
applications.
"We developed the Xplorer Helix configuration using our integrated dynamic
design and analysis platform," Long notes.
"It took careful planning and modeling to
optimize the drilling dynamics and ensure
that staggering the inserts would not interfere
with the patterns on the bits' other cones."
Long says the Xplorer Helix configuration is available globally, and has been
applied in multiple environments around
the world.
For example, the Kuwait Oil Company
selected an Xplorer drill bit with the
Xplorer Helix configuration to increase
ROP while drilling 4,500 feet intervals
through interbedded soft and hard formations. The operator needed to drill a
28-inch vertical section from 500 to 5,000

Arranging tungsten carbide inserts in a spiral array improves
roller cone bits' cutting efficiency
by putting more inserts into contact with new rock. Smith Bits, a
Schlumberger company, says
this innovation increases drilling
speed in many applications by
20-50 percent.

feet through limestone, dolomite, anhydrite
and shale layers, Long details.
Because this section had unconfined
compressive strengths ranging from 6,000
to 24,000 psi, Long says previous bits'
cutting structures would break and chip,

which reduced penetration rates. "With
the spiral configuration, the cutting structure, seal and bearing lasted long enough
to drill the section in one run. This saved
four drilling days and increased ROP by
107 percent," he reports.
r

Positioners Enable Rapid Build Rates
To optimize drilling, operators must
look at how the bit, motor, measurementwhile-drilling tools and other BHA components interact, suggests Ed Spatz, who
was one of the pioneers behind the first
steerable motors. With that goal in mind,
he assembled a multidisciplinary team-
including Mike Reese, who has 40 years
of experience in drill bits, and Jim Dudley,
an MWD and downhole tool expert-to
form an entity now called XR Lateral.
"One of the biggest issues we see is
that drillers need motors with large 2¼degree or 23⁄8-degree bent housings to
achieve the necessary build rates in the
curve," Spatz says. "These extreme bends
stress the motor and other drill string
components, capping the string rotation
speed, and therefore, the ROP the driller
can achieve without risking tool failure.
"At the same time, the high bend
angles cause the motor to rotate in an eccentric pattern that creates an oversized
and tortuous wellbore," Spatz continues.
"The extra hole drilled generates more
cuttings that need to be evacuated while
reducing the annular velocities that assist

with hole cleaning."
Spatz adds that eccentric rotation periodically slams the drill pipe into the side
of the wellbore, causing vibration and potentially damaging BHA components.
"We can reduce bend angle by 40-50
percent," Spatz says. "These 1 to 11⁄4
degree bend angles allow faster and more
concentric rotation, which improves penetration rates and hole quality. In addition,
our technology lets drillers achieve higher
build angles than are possible with standard
steerable motors."
To reduce bend angles, Spatz and his
team use a proprietary model to determine
how well the BHA's components work
together and decide where the BHA needs
to be positioned within the hole to optimize
its performance. Then they add Compound
Geometric Positioners (CGPs) to the motor's housing to keep the BHA in the optimum position.
"No longer is the motor's housing restricted to using no stabilization or a fullwrap stabilizer that is under hole gauge
and often completely ineffective, or a kick
pad for directional work," Spatz declares.

The compound geometry and precise
placement of the positioners lets them
come into play when the BHA is sliding
in the curve or rotating in the lateral,
Spatz says, emphasizing that this optimizes
contact and correctly positions the drill
string in both drilling modes. He adds
that the patent-pending technology enhances the directional driller's job, improving consistency from run to run.
In its first field test, which occurred
in the Permian Basin, Spatz says the positioners exceeded expectations. "The
build rate was within 10 percent of what
our model predicted, and it was 10 percent
higher," he details. "In addition, the tool
face control was excellent. During the
first 100 feet of curve, when tool face is
most erratic, tool face held within one or
two degrees of where the directional
driller wanted it."
Spatz says the CGPs are adaptable to
modern steerable motor technology and
will be beneficial in any directional application, including select parts of the rotary
steerable market, where they can achieve
comparable build rates at a lower cost. r
APRIL 2018 139

American Oil and Gas Reporter - April 2018

Table of Contents for the Digital Edition of American Oil and Gas Reporter - April 2018