INSTITUTO SUPERIOR TCNICO LISBOA

FPSO: managing environmental related

risks Technological and Natural Risks

Mariana Maral (n 71000) & Dominika Lesniakov (n 80002)

Prof: Manuel Heitor, Date: 2nd Semester 2014

1

Index List of Figures ............................................................................................................................ 2

List of Tables ............................................................................................................................. 2

List of Abbreviations ................................................................................................................. 2

Summary .................................................................................................................................. 3

Introduction .............................................................................................................................. 4

FPSO The most difficult industrial environment of Earth ..................................................... 5

Oil versus fishing ............................................................................................................... 5

Technology of FPSO .............................................................................................................. 7

Oil and gas production ...................................................................................................... 7

Mooring systems ...................................................................................................................... 9

Types of mooring systems ..................................................................................................... 9

Spread mooring system ..................................................................................................... 9

Turret mooring system .................................................................................................... 10

Pros and Cons of the Turret-Moored and Spread-Moored systems .................................. 11

Risks analysis....................................................................................................................... 12

How to protect FPSOs mooring systems? ............................................................................ 12

Real Time Monitoring of FPSOs (Tritech International Ltd) ............................................ 12

Cathodic protection (Deepwater Corrosion Services, Inc.) ............................................... 13

Alarm procedures ................................................................................................................... 14

Top 10 Potential Hazards .................................................................................................... 14

Hazard ranking ................................................................................................................ 14

Procedures to follow in case of an Alarm Situation .............................................................. 16

Formulation of the plan ................................................................................................... 16

Human factors................................................................................................................. 17

Case study........................................................................................................................... 18

Incident description ........................................................................................................ 18

Conclusion / lessons learned ........................................................................................... 19

Corrective action (MSS) ................................................................................................... 19

Conclusion / Discussion of Results ........................................................................................... 20

Bibliography ............................................................................................................................ 21

2

List of Figures Figure 1 - Dead whale in the coast of Ghana.............................................................................. 5

Figure 2 - The Kwame Nkrumah FPSO facility ............................................................................ 6

Figure 3 - Subsea field layout .................................................................................................... 8

Figure 4 - Spread Mooring system ........................................................................................... 10

Figure 5 - External Turret Mooring systems ............................................................................. 10

Figure 6 - Internal Disconnectable and Permanent Turret Mooring systems ............................ 11

Figure 7 - Real - time 360 riser and anchor chain monitoring for FPSOs .................................. 12

Figure 8 - Cathodic protection (RetroBuoy RB-4) ..................................................................... 13

List of Tables Table 1 - Comparative Summary of Turret Moored and Spread Moored FPSO Systems ........... 11

List of Abbreviations BP - British Petroleum

COW - Crude oil washing

CP - Cathodic protection

DP - Dynamic Positioning

FPDSO - Floating Production Drilling Storage and Off-Loading unit

FPSO - Floating Production, Storage and Off-Loading unit

FSO - Floating Storage and Off-Loading unit

ICCP - Impressed-current cathodic protection

LNG - Liquefied natural gas

OGP - The International Association of Oil & Gas producers

RAMS - Riser Anchor Monitoring System

SCU - Surface Control Unit

SPM - Single Point Mooring

VLT - Very Large Turret Mooring System

3

Summary

This project focus on the floating production, storage and offloading (FPSO) units used in

offshore oil and gas exploration. The study is composed of introduction, which consists of

describing FPSO, how strong is impact on the oil and gas industry as well as environmental

impact, and project contains the two major "issues" with critical implications for risk

governance in the South Atlantic:

a) mooring systems;

b) alarm procedures.

It makes use of case studies, along with information obtained from professionals and from

websites of oil and gas companies in order to have the highest quality information, aiming at

two main goals, namely:

identify the effectiveness of mooring systems;

identify hazard scenarios/events and potential associated human errors.

Conclusions of this work consist of answering two questions:

a) How to protect FPSOs mooring system?

b) What are the procedures to follow in case of an alarm situation?

We hope that our work will help in the further plans of the oil and gas industries as well as to

protect the world we live in together.

4

Introduction

Nature is full of countless examples of adaptation, from the long neck of the giraffe to the

natural camouflage of a chameleon. Adaptation, loosely defined, is the ability to become

better suited to an environment. In nature, it is a condition of survival. The world of oil and gas

production, specifically floating production, storage and offloading (FPSO) units, is in a

transitional state.

Increases in deep-water exploration and drilling over the past six-plus years have resulted in a

large number of new discoveries, which will now require development solutions. Market

forecasts suggest that there are more than 200 offshore oil and gas projects in the planning

and study phrases, which will require floating production solutions. The majority of these will

likely be FPSOs.

An Floating Production Storage and Offloading (FPSO - also called a "unit" and a "system") is

a type of floating tank system used by the offshore oil and gas industry and designed to take all

of the oil or gas produced from nearby platforms or templates, process it, and store it until the

oil or gas can be offloaded onto a tanker or transported through a pipeline.

FPSOs are effective development solutions for both deepwater and ultra-deepwater fields and

their main advantage is the ability to operate without the need for a specific export

infrastructure.

The key components of an FPSO are:

1) The vessel itself, which may be a new build or, more usually, a tanker conversion;

2) The mooring system, which is based on patented technologies and comprise a

promising niche market;

3) The process plant, whose configuration will depend largely on reservoir characteristics

and environmental factors; water and/or gas injection and gas-lift facilities are

commonly included.

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FPSO The most difficult industrial environment of Earth

An increasingly common aspect of oil production, floating production, storage and offloading

(FPSO) units are now a mainstay of many offshore oil installations. The ability to process and

store hydrocarbons in close proximity to drilling platforms allows producers to exploit oil and

gas reserves where laying an export pipeline is either impossible or not cost effective.

The unique operating environment of the FPSO and the relative rarity of such units can make

finding a suitable maintenance contract provider very difficult.

Oil versus fishing

Oil production worldwide has been synonymous with environmental damage, and Ghana is

proving to be no exception. Oil production 60 kilometres offshore has created problems for

the environment and the locals.

Since the exploration and subsequent production of oil, nine whales have been washed ashore

in Ghanas coastal Western Region: Jomoro and Ellembelle Districts (Figure 1). There are no

specific research which link the death of the whales to the oil extraction, but whale deaths

have been notably rampant since production began in 2009.

Figure 1 - Dead whale in the coast of Ghana

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The Kwame Nkrumah Floating Production, Storage and Offloading facility (Figure 2) in Ghanas

offshore Jubilee Field, operated by Tullow and partners. The powerful lights attract fish into

a "safety zone" that local fishermen cannot enter, and some fishermen complain of health

problems associated with excessive gas flaring.

Figure 2 - The Kwame Nkrumah FPSO facility

In March 2011, in the district of Nzema East, some fishermen developed reddened eyes and

skin rashes due to excessive flaring of gas. Maritime Law in Ghana prohibits fishing within five

hundred metres of the FPSO. The injured fishermen were respecting this safety zone limit.

The issue is on the restrictions to fish near the FPSO. Fish are attracted by lights on the FPSO

which are very powerful. As a result, the fish migrate into the zones where the fishermen

cannot reach.

Also there happened few accidents because of poor communication between fishing

community and the oil operators. Some fishermen have been losing their nets to the supply

vessels that traverse the waters to and from the FPSO.

Fish stocks have reduced over the years, partly because of poor management of the sector as

well as over population. Oil is now adding to the difficulties of the fishing industry. In that case

the oil company in Ghana wasnt prepared and did the strategic environment assessment after

they had found oil. Its necessary to prepare protective measures more specifically and protect

the community, fishermen and our environment. Also in the future prevent the accidents

which could happen for example like in the coast of Ghana.

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Technology of FPSO Oil has been produced from offshore locations since the 1950s. Originally, all oil platforms sat

on the seabed, but as exploration moved to deeper waters and more distant locations in the

1970s, floating production systems came to be used.

The first oil FPSO (Floating Production Storage and Offloading) was the Shell Castellon, built in

Spain in 1977. The first-ever conversion of a LNG carrier into an LNG floating storage and

regasification unit was carried out in 2007 by Keppel shipyard in Singapore.

FPSO and FSO systems today have become the primary method for many offshore oil and gas

producing regions around the world.

An FPSO is a floating production system that receives fluids (crude oil, water and a host of

other things) from a subsea reservoir. FPSOs have been serving the offshore oil and gas

industry for nearly 30 years. They have proved to be safe and economical.

Advantages of FPSOs are:

Early production;

Easy to remove and reuse;

Reduced upfront investment;

Can be used in any water depth;

Abandonment costs are less than for fixed platforms;

Retained value because they can be relocated to other fields;

Earlier cash flow because they are faster to develop than fixed platforms.

Over the years, advanced mooring systems as well as advancements in subsea equipment have

made FPSO/FSOs useful in deeper and rougher waters. Currently, approximately 160 FPSOs

and 100 FSOs are in operation worldwide.

Oil and gas production

The oil received from a subsea oil and gas field is not immediately ready for the refinery, as it

always comes with water, gas etc. This is why a processing installation is essential.

An FPSO is equipped with hydrocarbon processing equipment for separation and treatment of

crude oil, water and gases that arrive on board from sub-sea oil well reservoirs via flexible

pipelines. The separation process is a fundamental part of all hydrocarbon production. The aim

for operators is to produce oil free from gas and water, remove all liquids from gas, and

discharge produced water overboard within the environmental limits. Alternatively, water may

be injected to the reservoirs.

Treated oil is transferred to cargo tanks in the FPSO ships hull. Treated gas is either re-injected

back into the reservoirs or exported through a pipeline to shore.

8

Water and gas injection refers to methods where water and gas are injected back into the

subsurface oil reservoirs via injection wells (Figure 3), usually to increase pressure and thereby

stimulate production to increase oil recovery from an existing reservoir.

Alternatively, gas may be reinjected into an underground reservoir to store and save it if it

cannot be exported to shore.

Figure 3 - Subsea field layout

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Mooring systems

Ever increasing drilling and production in deepwater and arctic fields requires equipment of

highest quality and performance. To design a suitable mooring system for any floating

structure on sea is a big challenge.

To develop a preliminary mooring system design based on the consideration of steady

wind/current/wave loads/motions, wave-frequency loads/motions, and slowly-varying

loads/motions of the FPSO. Full loaded ship condition (100% loading) in 100-year survival

sea environment is considered in the design and analysis.

Types of mooring systems The most popular mooring systems used in the offshore industry are as under:

Spread Mooring - The spread mooring system seems to be the simplest way of

mooring an FPSO. The system consists of mooring lines attached symmetrically to the

bow or the stern. These connections can be relatively simple because the overall

system does not allow the floater to "weathervane".

Single Point Mooring (SPM) - Single Point Moorings are generally understood to be

associated with vessels moored at a fixed location which weathervane around a single

point. Different configurations of SPM provide position keeping to FPSOs. Nowadays

the most common configurations (by Bluewater and SOFEC, Inc. companies) are:

- External Turret;

- Internal Disconnectable Turret;

- Internal Permanent Turret;

- Very Large Turret (VLT);

- SPM Tower Yoke Systems;

- SPM Buoy Systems.

Dynamic Positioning (DP) - This method is not as popular as the first two, but slowly

getting there. There are no mooring lines required in this case. Basically, the technique

is to keep a floating structure stationary by means of controlling the magnitude and

the direction of thrust, based on position feedback.

Most FPSOs are ship-shaped and are "anchored" (moored) by a turret. The type of turret used

is determined by the environment of the FPSO. In calmer waters spread mooring is often

sufficient. In environments where cyclones or hurricanes occur disconnectable mooring

systems are used so that the vessel can be taken out of the storm's way and replaced when

the storm has passed.

Spread mooring system

10

Spread mooring systems (Error!

Reference source not found.) are

multi-point mooring systems that

moor vessels to the seabed using

multiple mooring lines. Usually

there are four groups of anchor

legs, arranged in a symmetrical

pattern, attached to the bow and

stern of the vessel. This style of

mooring maintains the vessel on

location with a fixed heading. Thus,

its application is dependent on a

site where the prevailing severe

weather is highly directional.

Turret mooring system

The turret mooring system consists of a turret assembly that is integrated into a vessel and

permanently fixed to the seabed by means of a mooring system and also it contains a bearing

system that allows the vessel to rotate around the fixed geostatic part of the turret, which is

attached to the mooring system. The turret mooring system can be combined with a fluid

transfer system that enables connection of (subsea) pipelines to the vessel like an FPSO.

The turret system is fully passive and does not require active vessel heading control or active

rotation systems in the turret or swivels. The turret system can be located externally (Figure

5), or internally (Figure 6) with respect to the vessel hull structure.

Figure 5 - External Turret Mooring systems

Figure 4 - Spread Mooring system

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Figure 6 - Internal Disconnectable and Permanent Turret Mooring systems

Pros and Cons of the Turret-Moored and Spread-Moored systems

The description of the two mooring systems discussed above has highlighted many of the

differences between a turret moored and spread moored system in terms of design and

performance. Table 1 provides a comparative summary between the two systems.

Table 1 - Comparative Summary of Turret Moored and Spread Moored FPSO Systems

TURRET-MOORED SPREAD-MOORED

VESSEL ORIENTATION 360 degree weathervaning Fixed orientation, can impact

flare

ENVIRONMENT Mild to extreme, directional to spread

Mild to moderate, uni- to fairly directional

FIELD LAYOUT Fairly adaptable, partial to distributed flowline arrangements

Prefers flowline arrangement to approach beam-on

RISER NUMBER & ARRANGEMENT

Requires commitment, moderate expansion capability

Can be designed for flexibility, additional tie-ins

RISER SYSTEMS Location of turret (bow) requires robust riser design

Adapts to various riser systems, combinations of various types

STATIONKEEPING PERFORMANCE

Number of anchor legs, offsets minimized

Larger number of anchor legs, offsets variable

VESSEL MOTIONS Weathervaning capability reduces motions

Dependent on relative vessel/environment directionality

VESSEL ARRANGEMENT Turret provides compact load and fluid transfer system

Components spread on deck, requires extensive interfaces

OFFLOADING PERFORMANCE

FPSO typically aligned with mean environment

Dependent on vessel/environment orientation

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Risks analysis The main risks on mooring systems occur during installation. One of the most problematic

operation concerning FPSOs mooring is called "Anchor Handling" - this process of mooring and

anchors installation are provided by specific company, which sometimes can take more than

one month, depending mainly on:

quantity of moorings and anchors;

kind of moorings and anchors;

environmental situation (weather, sea wind, waves etc.).

Risks involved during fabrication and platform operation are smaller than during installation,

because of several reasons:

1. Well chosen manufacturer based on the quality, fabrication procedures and

certifications.

2. Every step of fabrication are inspected and documented.

3. Materials are certificated and their welding are inspected several times and also

documented.

4. Manufacturer and installer own inspection and quality system.

5. The inspection of a certification company - such as "ABS Consulting" and "DNV GL",

in order to minimize the security risks during fabrication and during platform

operation life cycle.

How to protect FPSOs mooring systems? From the previous chapter we already know how to avoid or reduce risks and problems on

mooring systems during fabrication or installation processes and platform operations. But how

to avoid risks on mooring system during the process of drilling, how to protect mooring lines

and other components of mooring system and how to keep the operating life of those

components?

Real Time Monitoring of FPSOs (Tritech International Ltd)

Tritechs RAMS is a 360 anchor-chain

and riser integrity monitoring system for

Floating Production Storage and Offloading

Units (FPSOs). This technology is deployed

beneath the vessel and monitors the

presence, integrity and position of mooring

lines and risers 24/7 from a single sonar

head (Figure 7). In 2009, RAMS was

installed on the Petrojarl Foinaven FPSO,

where it continues to be in operation

today.

Figure 7 - Real - time 360 riser and anchor chain monitoring for FPSOs

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How It Works

The RAMS sonar head is controlled by the RAMS software which runs on a dedicated

Surface Control Unit (SCU). The RAMS software displays the known turret configuration as

a background to the real-time sonar imagery. Acceptable levels of movement for the displayed

targets are user definable, with any abnormal behaviour being easily identifiable. Internal and

external alarms are generated when the target behaviour falls outside the defined scope of

movement.

Advantages:

Unlike other monitoring systems for mooring lines and risers the Tritech RAMS

system is suitable for long-term deployment capability as it has no mechanical moving

parts.

RAMS provides continuous data recording, which allows detailed data export for

offline trend analysis.

RAMS is suitable for use on internal or external turrets and fixed or disconnect able

turret systems.

Cathodic protection (Deepwater Corrosion Services, Inc.)

Deepwater designs and manufactures cathodic protection systems for purpose-built and

conversion FPSO (Floating Production Storage and Offloading) structures.

FPSOs have many components, all of which require different types of innovative CP system

designs (moorings, hulls, ballast tanks and etc.). To design a system that protects the structure

as a whole, each part must be addressed separately.

To protect mooring chains, where

larger amounts of exposed steel

require a lot of cathodic protection,

Deepwater has routinely deployed

the RetroBuoy impressed-current

cathodic protection (ICCP) retrofit

system to the seabed. Providing up

to 400 Amps of cathodic protection

for 25 years, the Buoys are

connected to the FPSO by feed

cables deployed in a "Lazy S"

configuration back to the surface.

Whether turret-moored or spread-moored, each FPSO requires a slightly different

configuration. These adjustments are not unmanageable; the designers of Deepwater

company can modify the system to address these concerns.

The RetroBuoy RB-4 (Figure 8) is the newest model of RetroBuoy, rapidly becoming the

standard model for almost all applications.

Figure 8 - Cathodic protection (RetroBuoy RB-4)

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Alarm procedures

Human error is widely acknowledged as the major cause of quality, production, and safety

risks in many industries. Its unlikely that human error will ever be completely prevented, there

is growing recognition that many human performance problems stem from a failure within

organizations to develop an effective policy for managing human reliability.

Human errors begin during the design stage, extending beyond process and workplace design,

into construction and continuing into the design of management systems for operations and

maintenance. Such systems include management and training policies and procedural

development and standard operating procedure development.

Top 10 Potential Hazards

An identification and ranking of potential hazards was carried out in the Pre-project phase1

(Operational safe ty of FPSOs: Initial summary report - Jan Erik Vinnem), resulting in the

following list of hazards:

Hazard ranking

Marine and hull related accidents, structural impacts

M1 Hull failure due to extreme wave load

M2 Hull failure or marine accident due to ballast failure or failure during

loading/offloading operations

M3 Leak from cargo tank caused by fatigue

M4 Accident during tank intervention

M5 Passing vessel collision with FPSO or shuttle tanker

M6 Strong collision by supply vessel with FPSO or shuttle tanker

M7 Other vessels or floating structures operating on the field colliding with FPSO

or shuttle tanker

M8 Collision during offloading

M9 Rapid change of wind direction

M10 Multiple anchor failure

Hydrocarbon systems accidents

H1 Leak that may lead to fire or explosion in process plant

H2 Leak from turret systems that may cause fire or explosion in turret

15

H3 Leak or rupture of riser

H4 Impacting loads due to crane operations (swinging loads) on a moving vessel

H5 Dropped object from retrieval of cargo pumps

H6 Severe rolling during critical operations, such as crane operations (considered

as included in other scenarios, therefore not addressed separately)

H7 Topside fire threatening cargo tank

H8 Emergency flaring with approaching shuttle tanker or during off-loading

H9 Unintended release of riser

H10 Work in open air spaces during winter conditions

Auxiliary systems accidents

A1 Failure of cargo tank explosion prevention function during normal operation

A2 Fire or explosion in pump room

A3 Spill from off-loading system.

A4 Engine room fire or explosion

A5 Helicopter crash

The ranking of the hazards was based on frequency as well as consequence. The

classification of consequence reflects personnel consequences only, but it should be noted

that consequences to environment and assets largely follow the same patterns as the

consequences to personnel.

The following broad categories of risk resulted (starting with the highest):

Risk category 1: M2, M8, M9, M10, H1, H2, H3, A2

Risk category 2: M1, M4, M5, M6, H4, H5, H7, H10, A1, A3, A4

Risk category 3: M3, M7, H8, H9, A5

In addition to the risk categories reported above, two aspects were considered in

particular, i.e. the FPSO uniqueness and the importance of HOF. When these two additional

filters were applied, the list was limited to the following:

Risk category 1: M2 (ballast/loading/off-loading), M8 (collision during off-

loading)

16

Risk category 2: M4, (tank explosion during intervention), M9 (wind direction

change), H4 (swinging crane loads), H5 (deep well pump

retrieval), H10 (work in open air)

Risk category 3: M3 (working accident during tank intervention)

The majority of these hazards are associated with the cargo storage function directly or

indirectly, as follows:

M2, marine accident associated with ballasting operations during /loading and off-

loading

M4, tank explosion during intervention

M8, collision between FPSO and shuttle tanker during off-loading

H5, impact load on process equipment during retrieval of deep well pump

M3, working accident during tank intervention

Procedures to follow in case of an Alarm Situation

The emergency planning, the management competences and the communications

arrangements should be succinctly adaptable and robust to allow effective assessment of the

emergency as it develops and to ensure that all personnel are informed as to the action that

must be taken.

Although the topics required to be considered in the ERP are wide-ranging, the plan itself

should have a thread of simplicity running through it. It should be user-friendly to assist

understanding and enable confidence to be built up in the plan itself.

Formulation of the plan

The Emergency Response Plan (ERP) is part of the emergency response arrangements. It

should set out the operational and procedural part of the arrangements by stipulating:

Who does what

- Where

- When

- How, and

- To what effect

The ERP is a working tool that will be used regularly for training and practices, and will be the

basis upon which a real emergency will be handled. It needs to be clear with the emphasis on

ease-of-use and the practical information that would be required in an emergency.

17

The parameters of the plan should cover all stages of an emergency response from detection

of the emergency until the emergency is over and persons are considered to be in a place of

safety. For example, the stages in an ignited hydrocarbon release may involve detection,

alarm, firefighting, muster, evacuation, recovery from the sea and transport to shore (possibly

even via another vessel). Other emergencies will have a very different sequence of events and

equally should be accommodated by the plan.

Where onshore, regional or inter-regional facilities are required as part of the plan, the

interface between the F(P)SOs arrangements and the onshore arrangements should be fully

integrated. The plan should also consider what external notifications to government and other

bodies may be required by local regulations or by pre-arranged working agreements.

Weather conditions have a major impact on the options available during offshore

emergencies. The ERP should be developed to consider the implications of all expected

weather conditions upon the full range of emergency scenarios envisaged.

Human factors

In formulating the ERP and in carrying out the assessment, realistic assumptions need to be

made regarding the likely pattern of human behaviour in an emergency. For example,

increased stress, reduced visibility and extreme temperatures can severely reduce human

performance levels. Personnel should not be assumed to be both intrinsically capable and

reliable in carrying out all duties required of them. In particular:

Where a person is required to perform a key task as part of the ERP, it is essential that

factors relevant to its success (information flows, physical requirements etc.) are assessed to

ensure that the probability of a successful outcome is acceptably high and that the possibility

of the situation being made worse by incorrect actions being taken is considered.

The time allowed to complete actions, should adequately reflect the possibilities of delays

being introduced by stress, physical conditions etc. and not just be based on times obtained in

practices where such performance modifying factors may not be present.

The nature of the emergency may limit the time available for the decision making process.

The degree and complexity of the decisions that are required to be made should take these

constraints into account.

All personnel who have a significant role to play in the emergency plan should be identified

by role and function. Contingency arrangements should be put in place to accommodate injury

or unavailability of key personnel or information sources. The way in which the emergency

command and control structure will respond to changed circumstances should be considered.

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Case study

Incident description

Following an excursion incident during severe weather, where the Maersk Oil owned Floating

Production Storage and Off-take (FPSO) installation lost heading and parted 4 of 10 anchor

chains, it became necessary to provide a heading control/positioning assist tug at the bow of

the installation, on a short term basis, until such times as the integrity of the mooring system

could be re-instated and confirmed.

Initially following the Gryphon excursion incident this role was fulfilled by another Maersk

vessel, which is a sister vessel to the subject of this report. The main characteristics of this

Maersk vessel (and sisters) are, as follows.

During the night of 23rd February the weather increased to 5.5m significant wave height with

maximum waves of around 9 meters from a general South-easterly direction with wind gusting

to 65 knots were experienced.

It was reported by Gryphon that the offshore vessel was seen to deviate from his position

upwind of the FPSO and move to a position approximately 500m to the East of the installation

before returning to the correct position.

This occurred between 2030-2040hrs on 23rd February. It was ascertained from the vessel

Master that this excursion was the result of very large seas affecting the vessels heading

control whilst in manual operation.

He stated that 2-3 very large seas struck the vessel in succession which deviated the vessel

heading such that the wind took hold of the bow and the vessel moved bodily to the East.

The Second Officer was on watch as the sole watch-keeping Officer on the bridge at the time.

He was manoeuvring the vessel in manual mode through the use of individual controls for

main engines, rudders and thrusters.

The tow-wire was at 860 meters length and tension of the tow was at 55 tonnes at the time of

the incident. The tow-wire was held in position through the towing pins on the centre-line of

the offshore vessel.

The Master was called and quickly attended the Bridge where he took command of the vessel,

paid out some tow wire and corrected the vessels heading before gradually bringing the ship

back to optimum location.

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Conclusion / lessons learned

Immediate Cause(s)

Lost heading control of the vessel due to the effect of adverse wind and weather conditions.

O/O/W did not take appropriate action when the vessel stared to drift off its intended

position.

Unable to react to the changed circumstances.

Not calling the Master in due time in order to prevent the situation from escalating.

Vessels manoeuvrability and the effect of adverse wind and weather conditions not fully

understood by the O/O/W.

Watch instructions not followed.

Underlying Cause(s)

Operation not properly planned in advance.

Proper risk assessment / SJA not conducted.

Bridge team composition not efficient for the task.

O/O/Ws insufficient knowledge of the manoeuvrability of the vessel in order to take full

control of the situation.

Masters evaluation of the junior officers capability to take the sole watch responsibility.

No full understanding of the winch tension set-up and interface with the DP system.

Watch instruction did not include action triggers, e.g. weather criteria, power criteria.

Corrective action (MSS)

Share the incident and findings with the fleet.

Remind Masters to conduct risk assessment (Job Package System) prior to any operation

with offshore installations.

Review company procedures regarding Masters watch instructions to include action

triggers.

Review company procedures regarding bridge composition to ensure watch-keeping

arrangements allow for two watch-keeping officers being on watch at any time comprising, as

a minimum, one senior and one junior officer per watch.

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Conclusion / Discussion of Results

Floating Production Storage and Off-loading (FPSO) vessels have become increasingly popular

concepts in recent years, especially on marginal or small fields as they are cheap (especially

conversions of existing tankers). FPSOs are very flexible; theyve been used in thousands of

meters of water offshore Brazil to a few meters of water offshore Nigeria. FPSO uses subsea

trees to convert crude oil from offshore or subsea platforms onboard for next processing and

they are not capable as drilling facilities; although there were proposals for FDPSO, which is

FPSO with drilling capabilities (e.g. Azurite FDPSO owns by Prosafe SE).

Nowadays the most used options how to moored FPSO to the seabed are spread moored (in

calm waters) or moored with a turret, allowing the vessel to weather vane, in harsher waters.

All those systems have their own pros and cons and there are many certificated mooring

manufacturers who offers the best quality services.

Mooring system is one of the main key components of an FPSO. Besides the codes and

standards for mooring systems in the offshore industry and inspection processes of

certification companies, its necessary to protect mooring system while they are operating -

through the maintenance systems avoid or reduce the risks on mooring systems.

Tritechs RAMS technology has been installed on the Foinaven FPSO (owns by Teekay corp.)

since 2009 and shown to be 100% effective. BP company is confident of the system and its

ability to monitor the integrity of riser, umbilicals and its capability for data export in order to

analyse riser/ bend stiffener movement which is very important, not only to maintain the asset

but to identify the need for corrective action.

For protection of spread and turret moored FPSOs, the RetroBuoy (developed by Deepwater

comp.) anode-sled has proved very efficient and effective in providing cathodic protection for

the mooring. The most efficient and environmentally responsible cathodic protection.

No serious accidents with consequences to personnel have occurred on FPSOs in the North

Sea, but several near misses and less serious accidents have demonstrated a potential for

serious accidents. These incidents have also demonstrated that operational safety control is

important.

It can therefore be concluded that efforts to control operational failures are important for

FPSOs in particular, probably also for Floating Production Systems in general. This implies that

systematic efforts in order to manage and control operational safety aspects are important.

Risk assessment studies are required as basis for the identification of actions that may be used

to control operational safety aspects.

Potential causes of loss of operational control need to be addressed early in the design work,

in order to ensure proper inclusion of risk reduction measures in design and operational

planning.

21

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