captain jonathan mills. noble denton marine assurance, dnvgl oil & gas - offshore rig moves from...

DNV GL © 24th June 2015 SAFER, SMARTER, GREENER DNV GL © Noble Denton Marine Assurance & Advisory

24th June 2015

Captain Jonathan F B MIlls

OIL & GAS

Noble Denton Marine Assurance & Advisory

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Mobile Offshore Unit (MOU) Moves from the

Marine Warranty Surveyor & Towmaster Perspective

DNV GL © 24th June 2015


Introduction

Marine Warranty – Why?

Marine Warranty – Wet & Dry Tows/Moves

The Towmaster & Marine Representative

Tow Vessel Suitability – First Impressions

Practical Challenges

Jack-Ups in Particular

MWS Approvals, Best Practice & Competency

Tow Vessels What to Look for Inside & Out

Constant Issues

Questions

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Marine Warranty

A Marine Warranty Survey

is the Review, Supervision and

Approval of complex marine

operations such as “Rig

Moves” in the interest of

Client’s Insurance Company

and Underwriters.

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The extent of review and supervision is dictated by the insurers within their Warranty Clauses.



Marine Warranty

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MOU moves are basically of two types:

Wet Tow

Dry Transportation.



The Towmaster

The Tow Master, also known

as the Rig Mover, is

responsible for the

operational manoeuvring of

the MOU from one location to

another in accordance to the

approved towing plan.

The Tow Master instructs the

main and assist towing

vessels with regard to tow

wire deployment and the

various courses & speeds to

follow.

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The Tow Master is not in

overall control of the unit and

the OIM at all times remains

responsible for the overall

control of the unit. The Master of

lead towing vessel is legally

responsible for the tow.

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Marine Representative

Suitably experienced marine professional stationed on board the MOU who

represents the marine related interest of the Chartering Oil Company. Works

closely with, or reports directly to, the Company Man.

Ensures that the Oil Company’s applicable policies are adhered to at all times

during the move and installation of the MOU.

Ensures that the Oil Company’s assets are protected at all times.

Is responsible for monitoring all marine vessels under the responsibility of the Oil

Company.

Closely liaises with the OIM, Tow Master and MWS with regard to rig move

status.

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Practical Challenges During MOU Operations

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Poor Performance by Main Towing and Assisting Vessels.

Towing and assist vessels should be

inspected prior to move to ensure they

meet all Class and Port State Regulations

as well as against established technical

standards

Competency of Crew – with particular

regard to towage experience




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Bad Weather Accurate, continual and reliable

weather forecasts from a reputable weather forecasting company (x2)

Local anomalies Weather Routing – good and bad Watertight Integrity Shelter Areas and Safe Ports




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Determining unpredictable motions in seemingly good weather

Deceptive long period swell can induce extreme motions on a rig

Vietnam Seminar/F&G JU 2000_S.Leg Pulling.MPG




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Geographical and Location challenges

Tow to pass under bridges, power cables etc. Tow to pass over shallow areas, reefs etc. River passages, TSS transits etc.

Vietnam Seminar/MAGNUS - Bosporus Jack-Up Towage - Rig Move.mp4




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Jack up installations – Punch Through, stability, mechanical failures etc.



Jack-ups - Briefly

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Jack up is MOU comprising of hull, legs and jacking system such that it can be towed to a location, legs lowered into seabed and hull elevated to operating air gap.

Since the legs of jack up are supported by seabed, the soils have to be proven as a reliable foundation via preload operation which is simulation of maximum anticipated storm footing reaction by adding equivalent ballast weight.



Challenges with Jack-Ups

Leg Run, Punch Through: Seabed soils

can be unstable during installation or

even after the jack-up is elevated

particularly due to the presence of

stronger over weaker soil layers. In

this type of soil, rapid leg penetration

or drastic drop in the soil resistance

(“punch through”) may occur. If not

anticipated properly, a punch through

can cause major structural damages

with severe consequences.

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Challenges with Jack-ups

Interaction with Existing Footprints:

Many times jack-ups have to be installed

on disturbed seabed adjacent to or

overlapping with existing footprints. This

could lead to issues like leg sliding,

eccentric loading and rack phase

differences which results in difficulty

positioning the rig at the intended

location safely.

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Challenges with Jack-ups

Scour: Scour is associated with

jack-up deployment on a sandy

seabed with high bottom current.

Potential erosion of the spudcan

bottom contact with the seabed

may lead to eccentric support

and settlement of the spudcan

which affect the jack-up

behaviour and potentially

compromise structural integrity.

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Can be Mitigated by Integrated Structural & Geotechnical:

Leg Penetration Analysis

Punch Through Analysis

Site Specific Engineering Assessments

RPD Analysis

Spudcan Scour Potential & Protection Analysis

Seismic Assessments

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International Association of Marine Warranty Surveyors IAMWS

Established in 2013

Accreditation of MWS to minimum professional standard and code of ethics

Competency measured through testing and continuing professional development

Individual membership rather than tied to individual companies

Technical forum to share ideas, best practice and lessons learnt

Promotes open dialogue between MWS, underwriters and other stakeholders

Insurers & Underwriters have begun to assess the capabilities of MWS companies

– Local and global capability assessment

– Using pre-qualification criteria

– Scope of Work will state IAMWS accredited Surveyors

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MWS Approval Process for Wet & Dry Tow

Class, Port State etc.

Calculation of Bollard Pull Requirement for the tow

Review the Main and Emergency Towing Gear strength

Inspection of Towing Vessels

Motion Response & Longitudinal Strength Checks

Cribbing Strength and Positioning

Seafastening

Stability

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First Impressions



Check the vessels Class Certificates and the Towing Equipment

Certification first; that will give a good indication of the standard a

vessel is managed at.

PMS - CEO

Towing Log – Last Tow

Navigation Systems, Chart Corrections (Latest N to M)

ISM – DPA - Ask

Maritime Labour Convention – Rights, Complaints Procedure

Sanitary Certificate – 6 months

LSA & FFE Maintenance Logs

Certificates of Equivalency

DP Certificates and Log Books

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Tow Wires, Sockets, Pennants, Winches – Condition/Maintained/Op



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Towing Pins, Karm Forks, Shark Jaws, Stern Roller, Shackles



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Engine Room, Emergency Generator, Steering Gear & Thruster Spaces



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Bridge Equipment, Documents, Vision/View



Constant Issues

HRU’s & Liferaft Service Dates – Correct Installation

Crane Certification

Engine Room & Steering Gear bilges

Housekeeping

Oxy/Acetylene Cylinders

Fire Hoses

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Constant Issues

Escape Hatches

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Constant Issues

Watertight Integrity

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SAFER, SMARTER, GREENER

www.dnvgl.com

Questions

29

Captain Jonathan F B Mills

[email protected]

+65 97 595441

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