Drill challenging reentry well from 42-slot platform
Statoil planned to drill a reentry well from one of its 42-slot offshore
platforms in the Statfjord field, one of the largest and oldest fields on the
North Sea continental shelf. Slot recovery had become challenging in this
environment because of close-proximity wells and hole cleaning issues related
to mud system limitations.
In this specific well, Statoil expected to encounter severe packoffs
because of cement agitation in the 40-m rathole, located below the 9 5/8-in
casing shoe. Statoil needed an RSS capable of managing these conditions and
efficiently drilling the 8 11/2-in section on target.
Use PowerDrive Orbit RSS to remain on target despite well collision
risks
After modeling the dynamic downhole conditions of the Statfjord field
using VIRTUAL HYDRAULICS† software, Schlumberger experts recommended
drilling the well with PowerDrive Orbit RSS and WARP fluids technology. This
fluid contains micronized weighting material to improve hole cleaning and
requires a high flow rate of 2.3–2.35 m3/min, which can cause
standpipe pressure to exceed the limitations of conventional RSSs. Unlike a
conventional RSS, the PowerDrive Orbit RSS is designed with metal-to-metal
seals on the bias unit that expand the tool’s flow rate window.
Reached section TD on target and in one run
To avoid nearby wellbores and ensure sufficient hole cleaning,
Schlumberger conducted collar rpm surveys rather than pump cycling. The collar
rpm cessation surveys were coupled with magnetic ranging technology to allow
Statoil to drill close to an offset producing well at a minimum separation
factor of 0.18 and a center-to-center distance of 34 m [111 ft]. Statoil
drilled the 950-m section according to plan and in one run.
Despite experiencing stick/slip severity of 90–100% in the first
475 m of the section, the PowerDrive Orbit RSS drilled the reentry well on
target. As a result of the durability demonstrated on this job, Statoil plans
to use the PowerDrive Orbit RSS in other reentry wells in this field.
