Understanding risk

(in well integrity)

Stein Haugen

Professor

Department of Marine Technology

Presentation at Well Integrity Seminar, Stavanger, 10. June 2015

Stein.Haugen@ntnu.no+47 934 83 907

2

What am I going to talk about?

• What is the risk level?

• What is risk?

• Risk analysis

• Managing risk

3

4

Macondo in

Norway:

This may

be the

result if you

make the

wrong

decisions

5

What is risk?

6

7

What is risk?

“The words of risk analysis have been and continue

to be a problem….When our Society for Risk Analysis

was brand new, one of the first things it did was to

establish a committee to define the word ”risk”. This

committee laboured for 4 years and then gave up,

saying in it’s final report that maybe it’s better not to

define risk”

Stan Kaplan: The Words of Risk Analysis, Risk Analysis 17(4):407-17

8

Some alternative definitions

”Risk is an expression of the combination of probability for and consequence of an unwanted event.”

Norsk Standard 5814:2008

(unofficial translation)

Common formulation: R = p C

”Risk is the combination of the probability of occurrence of harm and the severity of the harm.”

NORSOK Z-013/ISO-IEC Guide 51

9

What is risk?

• I have a 0.1% probability (0.001) of completely wrecking my car in a year

• The cost of my car is 500.000 kroner

• Risk: 500 kroner per year

• Reality: Either I crash my car (and lose 500.000) or I don’t (and lose nothing)

• This may be regarded as average (long-term) risk

– Based on looking at many drivers for many years and distributing the losses among all these drivers

An enhanced understanding of risk

10

New definition by PSA“Risk means the consequences of the activities, with

associated uncertainty.”PSA, Guidance to Framework HSE Regs §11

Risk is not necessarily negative in this definition – the consequences of the activities are primarily positive (jobs, profit,…)

What has happened to probability?

Uncertainty = Strength of knowledge, Robustness

What does this mean?

11

Strength of knowledge

• Strength of knowledge: Can be interpreted as a

«measure» of how well founded our numbers are

– What was the basis for my probability of 0.001? Statistics

or guesswork?

• But is this constant? When throwing a (fair) dice:

– In the long term, we can be fairly certain that one out six

throws will give us a «6» - high knowledge strength?

– If we are going to throw the dice once – what is our

knowledge strength of the outcome? The only thing we

can say is that there are equal probabilities of all

outcomes – Low knowledge strength?

• Strength of knowledge depends on the decision

12

Robustness

• Hard to interpret directly – what is robust risk results?

• A rough definition of robust – unlikely to change

significantly even if assumptions, input values or

models are changed

• Can be tied to decisions – if the decisions that are

made on basis of the risk analysis are robust, then the

risk analysis can be regarded as robust?

– NB! This may depend very much on the decision!

• Both strength of knowledge and robustness depends

on decision – can our description of risk be separated

from the decision?

13

A short-term decision:What should I do tomorrow?

14

A long term decision:The weather is awful - I want to move!

15

Decision basis

Climate statistics?

Or weather forecast?

16

Risk analysis

• Risk analysis is a systematic tool for:

– Identifying what can go wrong in the future

– How likely it is that something can go wrong

– What the consequences are, if it goes wrong

• In theory, a good risk analysis should include all

relevant accidents

• Important tool for understanding, preventing and

preparing – basis for making decisions about risk

17

Risk analysis

• To a large extent based on average values

• The Kjerag risk analysis with a probability of 0.000000001 is relevant if the police have to make a strategic decision about whether to stop the public from jumping onto the boulder.

• For operational decisions (an individual deciding to jump onto the boulder), more specific information about the individual, shoes, if the boulder is slippery, if it is windy etc. is required.– After taking this into consideration, we may still conclude

that the probability is as low as calculated above – but it is based on more knowledge

– Same risk, different uncertainty

18

Types of risk analyses

Strategic analyses

Qualitative design analyses

Operational analyses

«Climate statistics»

«Weather forecast»

QRA/TRA

Risk matrix, SJA

FMECA, HAZOP etc

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Risk matrix

20

Risk matrix

• Wrong probability or

consequence

• One risk at a time – what

about interactions?

• Coarse risk ranking

• Little support for “marginal

decisions”– How can we decide if it is safe to

continue after a (small) problem

has emerged?

More precise risk analysis is required

21HAL 9000, from 2001: A Space Odyssey by Stanley Kubrick

”I've just picked up a fault in the AE35 unit. It's going to go 100% failure in 72 hours.”

22

Cost vs benefit

• A decision increasing risk:– Cost is a (very) small and usually not

quantified increase in the probability of something which is extremely unlikely (uncertain cost)

– The benefit is quantifiable (money, time, effort) and we know we will get it (certain benefit)

• Do we choose the quantified, certain benefit or the uncertain (small) cost?

• This is where the margins may erode, slowly but surely

23The problem is to know where the line is….

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Change in risk over time

• Single decisions have small effects

• Effect is not quantified

• Effect of all decisions is not accumulated

• Need to find ways of seeing the totality!

RIsk

Time

Change 1 Change 2

Change 3

Change 4 Change 5

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Major accidents

• Large consequences

– Immediate: Loss of life, environment, cost

– Long term: Legislation, operations, design

• Considered to «come out of the blue»

– Little correlation between major accidents and HSE track

record

• Complex causes – many factors influencing

• HAL9000 would have a tough job….

• Day-to-day operation/Barriers:

• Conditions that can change during the execution of an operation

• Technical problems, experience of crew, weather, availability of mud, etc

• Planning:

• Conditions decided during the well planning and that are not changed

during execution

• Drilling program, Well construction, Well specific and location specific

procedures, etc

• Preconditions:

• Given (natural) preconditions for the well that is to be drilled and other

preconditions decided very early

• Reservoir, ship traffic at location, available rigs, available equipment etc.

What influences major accident risk?

Visualizing the links

Re

se

rvo

ir

Reservoir

evaluation

philosophy Design basis

Drilling

technology/

equipmentMaintenance

plan &

procedures

Procedures

- Well

- Rig

Crew

Maintenance

/testing/

inspec.

Crew

- Equipment

(Choice of

SBV,

contingency

means etc)

Maintenance

plan &

procedures Lo

ca

tion

(W

ea

the

r co

nd, d

ista

nce

to s

ho

re, e

nviro

nm

en

tal v

uln

era

bility

)

Drilling

program

PLANNINGPRECONDITIONSDAY TO DAY

OPERATIONBARRIERS

Logging

36" hole, 30"

conductor

26"hole, 20"

casing

17½” hole,

13 3/8"

casing

8 ½” Hole

Well test/

flow test

Plug back

P&A

Casing &

CementMud

BOP

Wellh.

Casing &

CementBOP

Wellh.

Casing &

Cement

Contingency

plans and

procedures

(Move off, oil

spill, etc)

Maintenance/

testing/inspec.

Training

- Emergency

reponse drills

- etc

DAY TO DAY

OPERATIONBARRIERS PLANNING

ESD

Ignition source

control

Gas detection

Fire fighting

system

PA & alarm

Emergency

power

Ventilation

system

Escape and

evacuation

means

Available mud

Move off

location

WELL EVENT

Simultaneous

operations

- Competence

- Cost

-Competence

-Quality of plans

and procedures

-Time pressure

- Communication

- Competence

- Cooperation

- Roles and

responsibilities

-Competence

-Time pressure

- PTW system

- Roles and resp.

- Competence

- Cost

- Availability in

market

- Competence

- Time pressure

- Earlier wells

- Cost

- Availability in

market

- Competence

- Cost

- Time pressure

-Competence

-Communication

- Communication

- Competence

- Cooperation

- Roles and

responsibilities

-Communication

- Permit to work

system

-Time pressure

- Competence

- Cost

- Cost

- Availability in

market

-Competence

-Quality of plans

and procedures

-Time pressure

- Communication

- Competence

- Cooperation

- Roles and

responsibilities

- Competence

- Cooperation

- Time pressure

-Competence

-Time pressure

- Permit to work

system

PRE-

COND.

Maintenance

system

- Computer sys.

- Use of sys.

- Criticality anal.

Maintenance

Philsophy

- Cost

Mud pumpsElectrical

power

Cement

pumps

Diesel

supply

- Design

- Design- Logistics

- Design

Escape and

evacuation

Equipment to

disconnect

riser/anchors

Thrusters

Well-

head

Planning and

risk evaluation

- Competence

- Time pressure

- Communication

Mud Spec Mud Mixing

Mud/-

SeawaterDiverter

Major accident control

• Not only about barriers and barrier

management

• Technical, operational, organizational

• Need a more holistic view of what

influences risk

• Visualising how decisions made early have a

strong influence of risk

• Visualise management decisions and their

influence on risk

• Some small steps closer to HAL9000….

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To conclude

• Risk is an unavoidable fact – what we have to be

careful about is the «fine line»

• Current risk analysis methods are way too coarse

and not really suited for purpose

– Do not give the decision support we need

• A more holistic view on the situation is required

• A good starting point is systematic structuring of

information we have already

– Improved qualitative information is one step

– In the longer term: Improved quantitative information is

required