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Fugro Subsea Services Ltd Neil Gorshkov
Project Engineer
Multi Small Vehicle Intervention
and Innovative Subsea Tooling
Prolongs the Life of an Offshore
Platform.
Introduction
• Background to Annual Inspection
– Why Inspect
– Example
• The Problem
• The Solution
• Vehicles Used
• Bespoke ROV Tooling Developed
• Challenges to be Overcome
• Lessons Learned
• Conclusions
Background
• Most Operators perform annual inspection programmes to
confirm the integrity of offshore assets.
• Fugro Subsea Services Ltd perform inspection
programmes by ROV from purpose build vessels and from
structures.
• Todays presentation highlights the importance of such
inspection programmes and how multi small vehicle
intervention and innovative Subsea tooling helped to
prolong the life of an offshore platform.
Background – Why Inspect
• Video shows the type of anomalies we are looking for (in
this case a fatigue crack on a subsea structure).
Background – Example
• Combination of design flaws and inclement weather leads to
excessive stresses and strains within a structure.
• Constant presence of stresses and strains in excess of design
factors leads to crack formation.
• If cracks are left unchecked, loss of structural integrity will result.
• Cracks are normally terminated to stop propagation by drilling
holes at the end of the crack
• On the exterior of structures with good access this is normally
achieved by WROV or diver.
The Problem
• Cracks appearing within the interior of a subsea
structure.
• One crack observed on an internal bulkhead.
• Crack was propagating towards an internal strength
member.
• Intervention by divers or work class ROVs not viable
due to limited access and safety concerns.
The Solution
• Only option available was early intervention.
• Fugro Subsea Services Ltd developed an innovative
solution to the problem.
• Solution makes use of a bespoke drill and multiple
small vehicles.
Vehicles Used
Panther ROV
Falcon ROV
VideoRay
ROV
1300mm
470mm
220mm
Tooling Developed
• Mark I Drilling Tool
Tooling Developed
• Mark I Drilling Tool (Modified in Field) and Mark II Drilling Tool
Challenges to be Overcome
• Size constrained entry/egress point
ROV Access
Cutout (1m x
1m approx)
Challenges to be Overcome
• Convoluted Internal Route
Crack
Location
Arrows indicate route taken by ROVs and Drill
ROV
Job Site
ROV
Entry
Point
Challenges to be Overcome
• Placement of Drill With Falcon ROV
Crack
Location
View at the end of route taken on previous slide
Drill needs to be
placed at this
location
Challenges to be Overcome
• Placement of Drill With Falcon ROV
Challenges to be Overcome
• Challenging Work Environment
Footage from Falcon – currently sitting within structure interior
Pre Drilling Inspection
Footage from VideoRay – currently flying within structure interior
Drilling of Termination Hole
Footage from camera mounted on drill
Post Drilling Inspection
Footage from VideoRay – Opposite side of drill
Lessons Learned
• Visibility and ability to position accurately are key to
success.
• Control of cutter speed and feed rate of the cutter are
essential to performing a successful cut.
• Good co-ordination between the three ROV pilots (Panther,
Falcon and Video Ray) essential to minimise risk of
entanglement during operation.
Conclusions
• Tasks normally associated with work class ROVs can now
be conducted by smaller ROVs with bespoke tooling.
• Interventions can now be carried out in areas where,
previously, access was considered restricted due to having
to use a work class ROV to perform the operation.
• Response time to emergencies can be reduced as
mobilisation of a work class ROV is no longer necessary;
in-situ ROVs can be made use of instead.
• The use of small vehicles and
innovative subsea tooling helped
to prolong the life of an offshore
structure
Thank You