Multi Small Vehicle Intervention and Innovative Subsea ... gorshkov.pdf• Fugro Subsea Services Ltd...

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