Mature assets presented long-term well integrity challenges
A major North Sea operator planned to refurbish its offshore
infrastructure, which was installed in the 1980s and 1990s. Through its
ambitious North Sea renewal program, the company aimed to extend the life of
some existing platforms by performing long-term maintenance and equipment
upgrades in parallel with drilling and other activities.
Well integrity was a critical issue. Defects resulting from lack of
equipment maintenance and exposure to multiple forms of degradation and
external factors—such as corrosion, erosion, fatigue, physical impacts,
and environmental loading—can lead to catastrophic consequences.
Recognizing the need for a focus on engineering quality and reliability, the
operator approached Cameron for assistance.
Proactive engineering helped operator upgrade legacy technology
The two companies collaborated closely to review equipment design and
complete failure mode and effects analysis for defining failure probability and
criticality of components and identifying contingencies. Our fast response
times and ability to customize equipment helped to qualify alternative
solutions in preparation for future requirements.
On one platform, Cameron supplied three sets of equipment for the
water-alternating-gas (WAG) injection well, two for the production well, one
for the backup well, and two sets of running tools. Among the updates was the
installation of the Cameron compact wellhead system, which uses fast-makeup
connectors throughout and eliminates the need for at least one flange
connection, thus reducing field makeup time and the need for heavy torque
equipment. The wellhead was designed to interface with the existing starter
head, which housed the previously cemented 13 3/8-in casing string. Older-style
equipment could not be monogrammed to API 6A specification, so new equipment
now carries the API monogram. The new design incorporates double-sealing valve
technology in the interface between the bonnet and body on the lower master
valve and inboard valve on the A-annulus.
Four sets of 13 5/8-in SSMC standard snap-ring modular compact wellheads
for sidetracking previously drilled wells, three 5 1/8-in 10,000-psi Christmas
trees, and two sets of running tools were supplied on another platform. The
wellhead was again designed to interface with the existing starter head housing
the previously cemented 13 3/8-in casing string.
On a third platform, Cameron replaced outdated equipment and also
upgraded to single-stack 18 3/4-in BOP compatibility. A “dry”
system integration test (SIT) was performed for the produced water reinjection
project. The test involved a full stack-up with Christmas tree, spool, and a
three-stage SSMC wellhead.