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Oilfield Technology
June
2015
in Eastern Siberia. Drilling though 494 m of interbedded lithology
including limestone, dolomite, anhydrite, and 114 m of very hard
dolerite, the bit averaged 10% higher ROP than the best offset
result. All of the directional driller’s requirements were met, and the
section was completed in one run.
SuccesswithRSS
Another operator chose the 12 ¼ in. bit with a goal of completing
the section in a single run while improving ROP and reducing the
requirement to backream. The first run was marred by balling
issues caused by poor mud condition and drilling while circulating
on a single pump. Once the operator had these issues resolved,
the bit was re-run on an RSS assembly from 8293 ft and drilled
1987 ft to total depth with an average ROP of 69.5 ft/hr. This was the
first RSS run for a SpeedDrill bit, and in addition to providing this
above-average ROP, the bit easily met the goals for planned DLS
with 30 - 50% steering force and a maximum DLS of 3.5˚/100 ft.
Unconventional drilling
Typical well profiles in unconventional plays involve building
a curve and then drilling long horizontal sections to TD, with
the horizontal sections taking up to 7000 ft to complete. One of
the most cost-effective means to drill such wells is with positive
displacement motor (PDM) bottomhole assemblies (BHAs) with
bend angles for a directional control. But drilling on a bent motor in
rotational mode has long proven challenging for both the PDM and
the bit, and this complex, dynamic behaviour has rarely been fully
understood or even analysed.
The next generation of SpeedDrill bits is being developed by
utilising a new method for analysing the dynamic behaviour of
PDC bits on bent motor BHAs. At the heart of a proprietary new suite
of tools from NOV is the capability to analyse the complex trajectory
of the cutting structure of the bit to simulate the bottomhole
pattern (BHP) created in the rock.
These bits developed under this design process will provide
operator with a means to improve drilling performance based on
BHA criteria and drilling parameter selection.
Deepwaterdrilling
Some of the most common challenges in drilling deepwater
environments include, but are not limited to, BHA steerability,
rig equipment limitations, efficient operating parameters,
identification of both sediment and salt formations, hole cleaning
and hydraulics, salt creep, drilling fluid displacement, drillpipe
torque limitations, stabilisation
placement, lateral/ torsional
BHA vibrations, and more.
The new SpeedDrill bits
featuring increased lateral and
torsional stability along with
high drilling efficiency are being
developed as an ideal drill bit
solution to provide improved
penetration rates, high stability,
better hole quality, reduced
vibration levels, and lower
cost per foot for deepwater
applications.
Summary
In these challenging
environments and more,
drillers have reported a marked
difference in their operations
when using this line of bits.
And soon, advancements in
technology will also allow these
bits to increase performance
in the ultra-deepwater and
unconventional plays that will
dominate the future of the
drilling landscape.
Taking advantage of
increased stability and lowered
stress in the formation to
improve drilling efficiency, these
bits can also help reduce the
stress on an operation’s bottom
line. With its novel design
and marked improvements,
SpeedDrill bits are shown to
increase ROP, reduce the MSE,
and extend reach in challenging
environments.
Figure 2.
FEA Analysis simulating rock confinement – high stress equivalent to high confinementmeaning rock
that is harder to drill.
Figure 3.
FEA Analysis simulating the ‘stress relieving effect’ of SpeedDrill (Left: conventional drill bit. Right:
SpeedDrill).
