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Oilfield Technology
January
2016
Dri ll Bit Q&A
extensive field operating and performance data were used
to determine how changes in bit features and dimensions
affected characteristics – including steerability, bit walk,
DLS capability and vibration control – for a particular well
trajectory and BHA.
Abrasionresistance
Horizontal drilling performance in Canada’s highly
abrasive Montney formation is benefiting from tailored bit
design modifications and cutter enhancements. Precisely
altering bit wear profile, cutter positioning, and other
characteristics of a V613PDUX PDC bit has resulted in a
38 to 61% ROP increase and 55 to 105% increase in meters
drilled in two different Montney applications.
The bit redesign met objectives with an increase in
average ROP from a range of approximately 12 to 15 m/hr
to 15 to 19 m/hr while increasing meterage drilled from
300 to 500 m to approximately 700 to 800 m.
The 156 mm (6.125 in.) bit was modified over several
design iterations in which designers and field engineers
used proprietary design software to specifically address
the formation and application. The process employed
advanced algorithms, rock analytics, and extensive field
operating and performance data to determine how bit
changes impacted steerability, balance, cutter loading, and
vibration control for a particular well trajectory and BHA.
Design changes first focused on durability and overall
ROP. Cutters were repositioned to improve distribution of
loading forces across the face of the bit and increase the
diamond volume coming in contact with the formation.
Further enhancements to meet ROP and meterage
objectives incorporated a new PDC diamond material
composition. Using tests for measuring material toughness,
abrasion, and thermal stability, Varel now incorporates a
new cutter that is 30% more thermally stable and has 20%
higher abrasion resistance than previous cutters.
Figure 3.
‘One bit-oneBHA’ drilling in the Eagle Fordwith Varel Voyager bit eliminated trips and cut costs.
