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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
19
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….
24
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
25
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….
31
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
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