Drill a large-hole section through interbeded formation in one run
Total was drilling an offshore field development well from a
semisubmersible rig in the Laggan field of the North Sea. The operator planned
to kick off from a 20-in vertical casing and drill a 17 1/2-in section to TD in
one run. The wellplan called for a dogleg severity (DLS) of 2º/30 m.
Drilling the 17 1/2-in section in offset wells in this field had required two
bit runs, and Total expected to encounter interbedded higher-strength
formations while drilling this section.
Manage drilling risks with OptiDrill service to extend life of BHA
Schlumberger recommended using the PowerDrive X6 RSS and a roller cone
bit, complemented by the OptiDrill real-time drilling intelligence service, to
drill the section in one run. Prejob modeling using the IDEAS integrated
drillbit design platform helped to define suggested drilling parameters for
each type of formation Total was anticipating.
The OptiDrill service would enable the rigsite team to monitor downhole
BHA dynamics and quickly adjust drilling parameters to preserve the life of the
BHA, decreasing the severity of an event.
Reached section TD in one run while achieving smooth wellbore
Total drilled to section TD in one run, eliminating the second run that
is typically required to drill the 17 1/2-in section in offset wells in the
field. On-bottom ROP was comparable to that of offset wells, and overall
section ROP was significantly better because the second run was eliminated.
The section of the well crossed three faults and was drilled in
inclination-hold mode, a feature of the PowerDrive X6 RSS, which resulted in a
smooth wellbore. The smoothness was confirmed by real-time bending moment
information from the OptiDrill service.
The roller cone bit rotated 802,000 times while drilling the hole
section and encountered brief instances of bit bounce, which were detected and
mitigated. Average downhole WOB and downhole torque on bit measurements from
the OptiDrill service indicated the bit was performing as expected. Postrun
observation of the bit confirmed the diagnosis.