ELSEVIER pn:sO951-8320(97)00094-x

Reliability ,%q+wing and System Safety 60 ( 1998) 143- I5 I 0 1998 Ekvier Sciince Limited

All rigts mserved. Printed in Northern lmhl 0951-832@98/‘519.00

Adapting the application of risk analysis in offshore platform design to new

framework conditions

Urban Kjdlih* Norwegian University of Science and Technology, Department of Industrial Economics and Technology Management,

N-7034 Trondheim, Norway

This paper reviews results and experiences from a problem driven method development process within an ongoing oil field development project. Primary driving forces have been the NORSOK initiative to reduce overall project costs and new legislation on health, safety and environment. Four cases are presented, where risk analysis methods and practices have been changed to meet new needs. These cover needs of input to the selection of one platform concept from alternative standard concepts, specification and qualification of cost-efficient safety measures and analysis of the risk of occupational accidents. It is concluded that research may support the development processes through systematic evaluation and documentation. Significant areas of interest are standardization of risk acceptance criteria, development of risk analysis methods for special applications and evaluations of safety management programmes. 8 1998 Elsevier Science Limited.

1 INTRODUCTION

At the beginning of this decade, the Norwegian oil industry faced several challenges which threatened its profitability and long-term survival. A high cost level in field develop- ment and operation and low oil prices were common factors in these problems. New discoveries of oil and gas resources were of a small size, and the cost level for field development and operation made investments in these new fields unprofitable. Simultaneously, production from existing fields was starting to decline, and early close down due to high production costs and low revenues was foreseen. To maintain a high activity level on the Norwegian continental shelf, new cost-reducing strategies had to be developed.

In 1993, the so-called NORSOK initiative was launched to improve the competitiveness of the oil industry. Oil com- panies and suppliers co-operated in developing new phil- osophies and work methods. Ambitious goals were set, involving reductions both in field development and in opera- tion expenditures by 40-50s in 1998, compared with the 1993 level’. The reductions should be achieved, while the safety, health and environment (SHE) standard was

*Present address: Norsk Hydro ASA, P.O. Box 190, N-1321, Stabekk, Norway.

143

maintained or improved. These goals represent significant challenges to the oil companies.

Simultaneously, there were major changes in the SHE legislation. The Norwegian authorities had embarked on a new trend among European legislators. This involved a shift from detailed prescriptive SHE requirements to goal oriented requirements and to requirements concerning the industry’s application of risk analysis in the decision making process2.3. It was intended that the new legislation would provide more flexibility in choosing safety measures and avoid the need for frequent updates of the legislation as technology developed. These intentions harmonised with the NORSOK philosophies for cost reduction.

The NORSOK initiative and the new SHE legislation represented significant changes to the framework conditions of SHE management in offshore field development projects. To meet the SHE objectives, the internal safety management work processes had to adapt. The present paper focuses on how changes in framework conditions have affected the industry’s application of risk analysis. It is based on experiences from offshore projects, which have pioneered adaptations to the new framework conditions. The aim is to illustrate results of a problem driven methods development process during application of risk analysis in project work. It has been of interest to study why the changes in risk analysis methods were necessary, how they were accomplished and

144 U. Kjelh

what were the results. Research has only played a minor role should. reduce their efforts in the following up of in this development process. A further aim has thus been to su~liers. Technical simplifications and selection of identify how research can con~bute in the future to standard ~uipment should make the following up improve risk analysis methods development. tasks easier.

2 NEW FRAMEWORK CONDITIONS

2.1 The NORSOK initiative

4.

5.

The old work processes in offshore project work were judged to be bureaucratic and conservative. Typically, con- ceptual and detail engineering and fabrication were carried out in consecutive phases by different contractors. The oil companies required comprehensive documentation from each phase and monitored the contractors closely.

The main report from the NORSOK steering committee summarises the basic NORSOK philosophy for cost reduction’. The main elements are cultural change and new c~o~ration patterns to improve the value adding pro- cesses and avoid ~dund~t work. These basic principles had been discussed within the oil industry and been partly implements before the report was published in 1995.

reduced d~umen~tion. A reduction in documenta- tion by 50% was set up as a goal. Joint technical standards and selection of standard equipment should contribute to reduced documentation needs. decisions based on life cycle costs. Total costs, including costs for operation of the field, should be guiding factors in decisions during the project phases.

2.2 New legisbtion on health, safety and environment

2.1. I Cultural change New work processes needed to be developed. Principles from total quality management can be recognised in how these new work processes were character&d:

0 continuous improvements; l the customer in focus; l cooperation, trust and openness between oil com-

panies, contractors and vendors; l delegation of responsibility; l measurable goals for follow-up of progress; l bench marking.

In parallel with the oil industry’s efforts to reduce costs, the Norwegian authorities prepared a set of new detailed health, safety and environment regulations. These regulations replace the earlier, prescriptive legislation and are to a large extent based on goal oriented requirements. They cover such areas as explosion and fire protection, safety systems, e~rgency preparedness and the working environ- ment. The objective is to provide the indus~ with the necessary freedom of choice regarding technical and organisational solutions. Supplementary to these regulations is a set of guidelines, which further refer to European and international standards where applicable. These guidelines specify a minimum standard and describe design solutions that meet the requirements of the regulations. It is up to the oil companies to choose any design solution which meets the goal oriented requirements. It is, however, the duty of the company to document whether the selected solution is as good as that presented in the guidelines. This may be done by performing risk analysis.

2.1.2 New cooperation patterns In the new patterns for co-operation between oil companies and supplies, these total quality m~agement principles are applied. They involve:

1. development of joint NORSOK standards. Previously, each oil company maintained a set of technical specifications for use in project work. Because of the NORSOK initiative, the oil industry co-operated in developing new standards. These included stan- dards on technical safety, working environment and environmental care5-7. Considerable cost savings were foreseen in that the suppliers now faced a uni- form and co-ordinated set of requirements.

In 1981 the first risk analysis guidelines went into effect. Since then, quantitative analyses of the risk of major acci- dents have played a significant role in safety management of offshore field development projects. Major accidents are represented by a limited number of types of events with the ~tential of causing multiple fatalities or major damage to the insulation or the environment. The Norwegian off- shore ~dus~ and the authorities have gained considerable experience from these types of analyses. Recent changes in the risk analysis regulations leave it to the companies to decide the accepted level of risk and the types of risk analy- sis methods to be applied4. In addition, the scope of the regulations has been widened and now includes require- ments to analyse the risk of occupational accidents.

2. delegation of responsibility. New contract strategies were foreseen, where responsibility would be trans- ferred from the oil companies to contractors and sup- pliers. These were expected to have achieved the necessary competence to develop adequate technical solutions.

3 AN OIL AND GAS FIELD DEVELOPMENT PROJECT

3.1 Concept selection

3. reduced follow-up and inspection. Oil companies An oil and gas field development project with production start in 1998 is used here as an example to illustrate the new

Adaptation of risk analysis for offshore platform design 145

6 ’ S&CtiOll ahctlon daZ$kt of

l dopomtbl contmctor

Fig 1. Important milestones in the concept selection process.

applications of risk analysis. Fig. 1 shows a decision tree for the concept selection process. At an early stage it was decided to evaluate a subsea development with oil and gas wells tied in to a floating production unit. This decision was based on facts concerning water depth and existing infra- structure in the area. Two competing concepts, a production ship and a semi-submersible production, drilling and quar- ters platform were studied by the oil company’s project team. For each concept, a standard design offered by one of the suppliers was evaluated and only very limited engi- neering was performed. The technical-economic evaluation concluded with a recommendation to select the semi con- cept. Next, three different suppliers were invited to tender for the semi contract. In parallel, a plan for development and operation (PDO) was submitted to the authorities. A stan- dard design from one of the suppliers was selected, and conceptual engineering was carried out by an integrated company-supplier team during a 4 month period. Detailed engineering started 28 months before the scheduled produc- tion start time.

3.2 Implementation of NORSOK principles

For comparison, an existing process, drilling and living quarters (PDQ) platform with similar functions is selected. This platform is fixed and consists of a jacket and a topside

Old (W-l)

I

Vendors

r-l Vendors I I

module design. Production started in 1993, i.e. before the NORSOK initiative took effect.

Whereas the existing platform had been tailored to the specific conditions at the field, a standard floater design was selected for the new platform. This decision harmonised with NORSOK principles and had several advantages from a cost point of view. The various standard concepts were reasonably well known. Therefore, major decisions concerning concept selection and contract philosophy could be made before the alternative concepts had been defined in detail. This approach reduced time and costs for conceptual engineering considerably. The total costs of the floater including engineering and fabrication were sub- ject to competition. Cost reductions were accomplished by the supplier through a standard and fabrication friendly design..

New contract strategies, based on the NORSOK prin- ciples of delegation of authority to suppliers were imple- mented. Fig. 2 shows a simplified diagram of the relations between different contracts and responsibilities for follow- up. A main engineering, procurement and construction (EPC) contractor had overall responsibility for platform design after the start of detailed engineering. However, a larger share of the design work was done by subcontractors and vendors. For example, equipment vendors’ share of the total contract value used to be about 25%. This share

New (typical)

Main EPC contractor

I Eng.

contractor

I System Constr. EPC

vendors contractor contractor I I

Vendors

Fig. 2. Comparison of contract strategies for the platform for the old and new projects. E, engineering; P, procurement; C, construction.

146 0: Kjellth

f(N) curve for fatalities Number of l ccidants pr. year

L0ss of evacuation Numkr of accldonta pr. yrr

1 10 100 1 10 100 1000

Numbor of fatafltios NumbrofporsonsInUr,u#

Fig. 3. Acceptance criteria for personnel risk.

increased to about 50% in the new concept. For certain types of standard equipment, the oil company signed frame agree- ments with suppliers. These frame agreements were taken over by the EPC contractor for adaptation to the actual application.

Costs for design and fab~c~ion of the new platform are about 30% lower than those for the existing platform. Also, the time from start of detailed engineering to first oil has been reduced considerably, from 40 to 28 months. Reduced manning has been a key component in reducing operation costs, in the order of 40-50%. However, NORSOK’s goals conce~ng cost reductions in capital expenditure have not been met fully.

Implementation of NORSOK principles involved several challenges to the oil company’s SHE management. Pre- viously, extensive concept risk analyses of the alternative concepts had served as input to concept selection and documentation to the authorities. It had thus been necessary to develop a well defined concept design. Now, risk analyses of the alternative concepts had to be made on a less well- defined basis, leaving it to the main EFC contractor to verify the acceptability of the detailed design solutions. Simulta- neously, the oil company’s follow-up of the EPC contractor and the various subcontractors and vendors was reduced due to the new contract strategy. However, the oil company retained overall ~s~nsibility for the safety of the new concept.

4 FOUR APPLICATIONS OF RISK ANALYSIS

Several risk analyses have been performed as input to deci- sions in the various project phases. This paper gives a short presentation of four cases, where changes in framework conditions have generated the need to develop new methods and applications of risk analysis (Table 1).

4.1 Acceptance criteria

According to Norwegian risk analysis regulations, oil com- panies have to develop acceptance criteria concerning the risk of losses due to accidents. New &sign solutions have to

be qualified in relation to these acceptance criteria by use of risk analysis. Acceptance criteria to risks to personnel that apply to the new platform are given below:

Risk of fatalities. The accepted frequency of fatal- ities for a platform with 100 people on board is shown by the flN) curve in Fig. 3. Loss of evacuation possibilities. There shall be an upper limit on the frequency of losses of means of evacuation from areas outside the immediately affected area by the accident. This limit is deter- mined by the average number of personnel in the area (Fig. 3). Explosion barriers. The atmual frequency of impair- ment of explosion barriers between areas shall be less than 1 X 10e4. Frequency of occupational accidents. The fre- quency of occupational accidents shall not be higher than for comp~able platfo~s in operation. Environmental risk. The frequency of accidents which cause serious damage to the ecological system shall not exceed low4 per year.

4.2 Case 1: ~~b~hrnent of design requirements to s&sea barriers

A basic NORSOK principle to reduce costs is to select standard equipment, e.g. by entering into frame agreements with suppliers. One example of such standard equipment is templates for subsea wells.

The templates are exposed to risk of damage due to dropped objects during drilling and well intervention opera- tions. Traditionally, the templates have been equipped with an extensive protective structure to avoid damage that may result in blow out or rupture of flow lines or manifolds. This design used to be verified in the concept risk analysis, which served as an attachment to the plan for development and operation (PDO).

The question was whether this protection could be reduced or deleted without violating the acceptance criteria for the risk of environmental damage due to release of

Tabl

e 1.

Fou

r ne

w a

pplic

atio

ns o

f ris

k an

alys

is d

urin

g de

sign

Type

of

anal

ysis

R

easo

n fo

r in

trodu

ctio

n of

new

app

licat

ion

Rut

-Pos

e M

aior

diff

eren

ces

in r

elat

ion

to e

arlie

r pn

?iect

s

Cas

e 1:

Ana

lysi

s of

env

ironm

enta

l ris

ks

due

to b

low

out

Cas

e 2:

Del

ta a

naly

sis

of m

ajor

ac

cide

nt r

isks

Cas

e 3:

Sen

sitiv

ity

anal

ysis

of

eff

ects

of

alte

rnat

ive

safe

ty m

easu

res

Cas

e 4:

Wor

king

env

iron~

nt

risk

anal

ysis

New

pro

cure

men

t ph

iloso

phy

invo

lvin

g fr

ame

agre

emen

ts

with

sup

plie

rs o

f st

anda

rd s

ubse

a eq

uipm

ent

Proc

urem

ent

of s

tand

ard

plat

form

de

sign

rat

her

than

dev

elop

ing

new

pl

atfo

rm s

olut

ion

Red

uce

cost

s fo

r sa

fety

mea

sure

s

Mee

t ne

w r

egul

ator

y r~

uire

men

~

Def

ine

min

imum

re

quire

men

ts

to d

ropp

ed

The

risk

anal

ysis

w

as c

arrie

d ou

t be

fore

the

ob

ject

pro

tect

ion

of s

ubse

a sy

stem

s as

pl

atfo

rm c

once

pt h

ad b

een

defin

ed.

An

inpu

t to

fra

me

agre

emen

ts

acce

pted

con

tribu

tion

from

dro

pped

obj

ect

risks

to

the

tota

l ris

k w

as d

efin

ed r

athe

r th

an

sum

min

g up

all

cont

ribut

ions

an

d co

mpa

ring

thes

e w

ith t

he a

ccep

tanc

e cr

iteria

. Fu

nctio

nal

requ

irem

ents

to

sub

sea

barr

iers

wer

e de

fined

as

a r

esul

t of

the

ana

lysi

s ra

ther

tha

n ve

rifyi

ng

a pa

rticu

lar

solu

tion

Sele

ctio

n of

pla

tform

con

cept

and

R

e-us

e of

ear

lier

risk

anal

yses

of

stan

dard

ve

rific

atio

n of

cos

t es

timat

es

conc

epts

. Se

miq

uant

itativ

e ev

alua

tion

of d

if-

fere

nces

bet

wee

n th

e ne

w c

once

pt a

nd t

he

conc

epts

tha

t ha

d be

en a

naly

sed

befo

re.

Focu

s on

crit

ical

des

ign

elem

ents

, w

here

the

sta

udar

d de

sign

with

out

addi

tiona

l sa

fety

mea

sure

s vi

olat

ed t

be a

ccep

tanc

e cr

iteria

Se

lect

ion

of c

ost-e

ffic

ient

so

lutio

ns

The

proj

ect

prop

osed

saf

ety

mea

sure

s an

d to

mee

t th

e ac

cept

ance

cr

iteria

ar

raug

ed t

hese

in

orde

r of

pre

fere

nce.

The

th

ird p

arty

mad

e a

sens

itivi

ty

anal

ysis

, ba

aed

on a

ful

l co

ucep

t ris

k an

alys

is,

to d

efin

e th

e m

ost

cost

-eff

icie

nt

solu

tion

To v

erify

des

ign

and

to d

etai

l N

ew a

pplic

atio

n of

a c

ombi

~on

of r

isk

g~-o

~en~

re

quire

men

ts

anal

ysis

m

etho

ds i

n a

com

pr&

tens

ive

anal

ysis

of

the

who

le p

latfo

rm.

Split

of

~~ns

i~lit

y be

twee

n co

mpa

ny

and

cont

ract

or i

n pe

rfor

m-

ing

the

anal

ysis

148 U. KjellPn

Fig. 4. Method for analysis of dropped object risks for subsea installation.

hydrocarbons. An answer to this question was needed as input to specifications for subsea systems in frame agreements.

The traditional approach in the concept risk analysis of earlier projects was modified to make it possible to select a cost-efficient protection for the standard design at an earlier phase, i.e. before the total concept had been defined. Here, the presentation of the applied method focuses on the analy- sis of the risk of blow outs due to dropped objects with consequences to the environment (Fig. 4). T~~tionally, the analysis proceeded from left to right in the figure. In the present case, it started at both ends and followed the arrows in the figure. It was assumed that the cont~bution from dropped objects to the risk could be allowed to make up a certain share of the acceptance criteria ( 1%). Event tree techniques were then applied in calculating accepted fre- quencies of blow outs from dropped objects. Traditional methods were also applied in calculations of expected fre- quencies of dropped objects and hit frequencies. These were based on assumed drilling and well intervention pro- grammes and template layout and historical data on dropped object frequencies. Functional requirements to subsea bar- riers were then established, which expressed the accepted conditional probability of blow out, given a hit by an object with a certain energy impact (Table 2).

The results showed that there was scope for reduction in pro~tion of the template, comp~ed with the lotions design, without violating the acceptance criteria for environmental damage risks. Design of the protection could be based on economic considerations, where risks of losses due to property damage were compared with costs of the protective structure.

Table 2. Examples of functional requirements to subsea bar- riers to prevent blow out, when different dropped objects hit the template. A combination of barriers (down hole safety valves, X-tree valves, protective structure) shall meet the

requirements

Dimensioning dropped object

Energy WI Accepted probability of blow out when the template is hit by a drop@ object

Crane 650 0.70 Crane boom 42 0.10 Work over riser 15 0.50

4.3 Case 2: selection of concept among standard platform alternatives

Traditionally, the project developed alternative tailor-made concepts based on conditions at the field during the feasi- bility study phase. These development alternatives were then evaluated from an economic and safety point of view. The oil comfy was responsible for the qu~ification of the concepts in relation to the risk acceptance criteria. A full concept risk analysis was executed for each major development alternative by a third party.

Recent developments have changed the situation com- pletely. Major suppliers now offer standard concepts that are flexible enough to meet the specific conditions at differ- ent fields.

In our present example, a standard production ship and a standard semi PDQ platform from two different suppliers were evaluated during concept selection. In a full imple- mentation of the NORSOK philosophy, it would have been the duty of the suppliers to qualify their solutions for this application. However, no such documentation was available from the suppliers. The approach selected by the evaluation team shows possible future development. The team had access to d~umentation from other projects on concept risk analyses of the two alternatives. So-called delta analyses were performed. Differences between the new applications of the ship and semi alternatives and the applications that had been analysed before were identified. These were treated as sensitivities and their implications for personnel risk were assessed. The analyses focused on elements of the standard design, which the previous analyses had identified as critical from a safety point of view.

Two different sets of risk acceptance criteria from two different companies had been employed in the earlier con- cept risk analyses. It was still possible to use the results in the evaluations of the new development alternatives, since standard risk analysis methods had been employed in both analyses.

Concerns regarding potential violations of the risk accep- tance criteria of the new field were identified for both stan- dard development alternatives (Table 3). Remedies were identified and the cost impact was evaluated. It was con- cluded that both concepts were feasible from a personnel risk point of view.

Based on economic considerations, it was decided to pursue the semi alternative. Different suppliers were invited to tender for this alternative. The final decision on type of semi was only made after the PDO had been handed over to the authorities. To save time, the same semi that had been evaluated in the concept selection process was selected as the PDO alternative. Documentation on this type of semi was developed further to meet the expectations of the authorities. A more extensive documentation of the delta analysis was carried out by a third party. Compared with earlier projects, this delta analysis still represented a con- siderable reduction in d~umen~tion of the concept risk

Adaptation of risk analysis for ofihore platform design 149

Tabk 3. Deita analysis of possible violations of acceptance criteria

Concept Special characteristics of the new concept Accident scenarios where additional safety measures compared with the earlier analysed concept had to be considered

Production ship

Semi PDQ

Lower number of risers but a higher operating pressure. More complex swivel. Different process layout. Lower manning Lower blow out frequency but higher flow rates. Different subsea layout. Larger number of risers and operating pressure. Different process layout

Jet fires due to swivel leaks, which represent a threat to escape. Riser leaks b&w living quarters, which expose muster area and life boats Burning riser leaks, which expose the substructure and may cause the platform to collapse

analysis for the PDO. The reduction in documentation had been accepted by the authorities in advance.

4.4 Case 3: selection of safety measures on a cost- efiiciency basis

A traditional concept risk analysis was carried out by the chosen contractor during the conceptual engineering phase. As expected, the results showed that the basic design did not meet the risk acceptance criteria for evacuation. Ignited riser leaks contributed significantly to these violations.

In earlier projects, the third party had made recommenda- tions on safety measures as part of the risk analysis. These were evaluated by the project and the selected solution was verified by the third party. Several iterations could prove necessary before the final solution was chosen and adequate documentation was provided.

This procedure did not ensure the timely implementation of cost-efficient safety measures. An alternative approach was selected, where the project came up with a set of safety measures after the preliminary results were available. These were arranged in order of priority, investment and opera- tions costs serving as the most important input. The third party then carried out a sensitivity analysis to calculate the contribution from different measures to a reduction of the risk (Table 4). These results were included in the final version of the risk analysis report and allowed the project to select a combination of safety measures on a cost-efficiency basis.

4.5 Case 4: analysis of the risk of accupational accidents

The scope of the risk analysis regulations that went into effect in 1991 is wider than that of earlier guidelines and includes traditional occupational accidents as we114. New regulations

relating to the follow-up of the working environment in pet- roleum activities further define the requirements to the appli- cation of risk analysis in this area’. These different requirements had to be considered in developing the new NORSOK standard on ‘Working environmentV6. This standard is based on the general principles of the EN-IS0 9001 standard on quality systems, which defines the responsibilities of sup- pliers. The NORSOK standard specifies design requirements and requirements to analyses to be performed by suppliers. These analyses have two purposes: to verify design and to detail goal oriented requirements to the working environment.

Fig. 5 shows how different analyses of the risk of occupa- tional accidents were applied in the development of design in the new project. Both job safety analysis and comparison analysis had been performed in earlier projects9”‘. This application, however, is new in that: (1) the two analyses are combined in a comprehensive approach covering the whole platform and (2) the responsibility for the analysis is split between company and contractor. It shows how the NORSOK philosophy on new co-operative patterns has been implemented in a work process, where risk analyses play a central role.

An experience checklist was developed by the oil com- pany. It was based on an analysis of accident data from two reference platforms in operation. The accident data base Synergi was employed in the analysis”. Statistics on acci- dent black spots and recommendations on how to prevent these were handed over to the EPC contractor.

The contents of the checklist can be illustrated by an example. There were 21 injuries with knives in the data base from the kitchen at the two reference platforms. For the prevention of accidents with knives, it was recom- mended that all cutting work be carried out outside trafficked zones and that height adjustable work benches be provided.

Table 4. Contribution to a reduced frequency of loss of evacuation from different remedial actions

Area Acceptance criterion

Calculated frequency per loo0 years with no measures

Reduced frequency per 1000 years for different measures

Prucess Drilling Utility Living quarters

4.9 2 3.4 I

10.5 4.9 4.2 4.2

Fire protection of Protection of Ship collision sub structure risers protection

- 2.2 -5 - 1.5 - 3.8 - 2.7 -1 - 3.8 - 2.7 -I - 3.8 - 2.7 -1

150 U. Kjellpn

;‘................,..........,...... i i Accident i I -ANY

Fig. 5. Use of analyses of the risk of occupational accidents in design.

In the next step, the contractor carried out job safety analyses. These were based on inputs from the design, and project and operations personnel participated in the analyses. Subsequently, the oil company carried out a so-called ‘com- parison analysis’ ‘O. The number of accidents per year for different operations was estimated for the new platform. Accident statistics for the reference platforms served as a basis for these estimates. Estimations were made by an expert panel and were documented thoroughly. They represented the best joint judgement by the project and operations team’*.

Table 5 presents an overview of the results. The total number of accidents per year is expected to decrease somewhat. A reduced number of accidents in maintenance contributes to this decrease. This has to do with improved equipment handling during maintenance, improved equipment reliability and improved maintenance plans. The number of accidents in drilling was expected to increase, mainly due to an increased activity level and due to increases in the risk of accidents due to floater movements. Based on manning figures, the expected LTI rate was calcu- lated for the new platform. This was lower than the historical rate for the reference platforms. The acceptance criteria for the risk of occupational accidents were thus met.

4.6 Discussion

The cases presented illustrate a trend in the application of risk analysis. Previously, the main emphasis has been on

Table 5. Results of a comparison analysis of the new platform

Activity Expected number Historical data on of accidents per the number of year for the new accidents per year for

platform reference platforms

Catering 4.2 4.5 Operation 1.8 1.5 Drilling 4.2 3.8 Maintenance 3.8 4.7 Walking I .7 1.7 Others, unknown 0.4 0.3

Total 16.1 16.5

documentation and veriiicati?n of design. It has now shifted to an active use of risk analysis during design development in the identification of needs of safety measures and in the development of cost-efficient solutions.

The cases show how risk analyses have become mote focused and tailored to the specific needs. Extensive use is made of experiences from operations as well as from earlier analyses. A concentration of resources to critical items is allowed for, and a more systematic build-up and use of experiences is possible. These factors contribute to make the resuhs of the risk analyses more robust. The analyses may, however, become too superficial, for example, when analysing new applications of standard design. Possible new risks may not be carefully considered. This concern is especially obvious when a contractor is responsible for the verification of the new application of the contractor’s own standard design during tendering or execution of lump sum contracts. It is a policy question, whether in-house analyses by the contractor’s own personnel can be accepted by the oil company, or whether the analysis has to be made by a third PartYe

Two of the cases show how cost-efficient solutions can be selected through the co-ordination of the implementa- tion of goal-oriented requirements with the application of risk analysis. In this way, expensive solutions with a mar- ginal impact on safety can be avoided. There is a risk, however, that too narrow a focus on cost-efficiency and optimisation will result in a reduced total safety margin. This is a concern when considering the uncertainties that still exist in the current analyses. Deviations from ‘good safety engineering practice’ must be evaluated carefully. Qualification and documentation of the risk analysis methods are required but have yet to be given adequate attention.

Timing of the risk analyses is a crucial question in the new projects, where the realisation phase has been dramati- cally reduced. The results of risk analysis are often needed before enough information about the concept is available for the analysis. The analysis must thus be based on a number of assumptions, which may change in the course of the project. Experience shows that the follow-up of assumptions is of equal importance to follow-up of results and recommendations.

5 RESEARCH NEEDS

5.1 Standardisation of acceptance criteria to personnel

The examples presented show the need for standardisation of the acceptance criteria of different oil companies. New standard design solutions, both for total concepts such as production ships and semi PDQs, and for individual systems and components, have to be qualified. This is the responsi- bility of the suppliers. Since the acceptance criteria differ between oil companies, suppliers currently have to meet varying requirements. Research may support the oil

Adaptation of risk analysis for oRshore platform design 151

companies in developing a joint basis for selection and doc- umentation of acceptance criteria. Important items are his- torical data on accidents and evaluations of existing risk acceptance criteria and risk analyses.

5.2 Development of risk analysis methods for specific PUW@=

Traditionally, the major risk analysis consultants have pro- vided concept risk analyses to support the oil companies in satisfying the requirements of the authorities. The need for cost~~cient decision support was of secondary concern. The examples presented here demonstrate how recent developments, in line with NORSOK philosophy, have gen- erated new needs of risk analyses. Research may support the necessary development work by documenting and qualify- ing various standard methods that meet the new needs.

5.3 Evaluation of the safety management work processes

Safety m~agement faces sig~fic~t new challenges when cost-reduction becomes a central issue. There is a need to evaluate the safety management activities in the new projects. Systematic evaluation will support the adaptation of safety management principles and methods to new needs by speed- ing up the building of experiences and by providing correc- tions of negative developments.

6 CONCLUSIONS

NORSOK has been a necessary driving force in recent developments in the Norwegian offshore industry. Safety management has adapted to the new situation to ensure a maintained safety level. This paper illustrates this adapta- tion by presenting exampies of new methods and applica- tions of risk analysis. The necessary development work has so far taken place in the ongoing projects and has been driven by practitioners. Research may help to make the

learning curve more steep through systematic ev~uation and documentation of experience. This can only be achieved through a close co-operation between research and practice.

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