T
he drilling industry has known for more than 30 years that
the stress state of the formation around the bit and drilled
well is significantly lowered once penetrated by the bit.
However, conventional PDC drill bits are unable to take advantage
of this reduced stress having already drilled the borehole. If a
drill bit could use this phenomenon to its advantage it could
greatly improve the efficiency and economics of an operation.
It was with this concept in mind that NOV designed
ReedHycalog™ SpeedDrill™.
Previously, bi‑centre bits had been observed in a number of
applications as being able to drill and enlarge a hole faster than
a PDC bit could drill an equivalent hole. This prompted engineers
at NOV to evaluate whether the same could be achieved with
a concentric fixed‑cutter bit. With a two‑stage, dual‑diameter
SRI MARKANDEYA AND ANDREW MILLER, NOV,
SHOW HOW
TAKING ADVANTAGE OF LOWER STRESS IN THE WELLBORE CAN
PROVIDE RELIEF FOR OPERATOR’S BOTTOM LINES.
COVER STORY
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