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