Risk The Road to Eliminating Operator-Related Dynamic Positioning...

Risk

The Road to Eliminating Operator-Related Dynamic Positioning Incidents

Arjen Tjallema – Bluewater Energy Services BVClemen van der Nat – Bluewater Energy Services BVHugo Grimmelius – Delft University of TechnologyDouwe Stapersma - Delft University of Technology

October 9-10, 2007Return to Session DirectoryReturn to Session Directory

MTS DP Conference -- Houston 2007

The Road to Eliminating Operator Related DP Incidents

Arjen Tjallema . Hugo Grimmelius . Clemens Van Der Nat . Douwe Stapersma

2MTS DP Conference -- Houston 2007

Introduction

• Operator involved in majority of DP incidents

• Nature of DP incidents• Role of DP operator• Modes of operation• Monitoring DP

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Incident process

time

wor

kloa

d

faultinitiation

faultdetection

detectiontime

faultidentification

generation ofsolution strategy

system’sreaction

available time

incidentoccurs

time needed to solve problem

incidentprevented

or

solutionimplementation

problemsolved

(if action successful)



The operator’s role

• Level of automation• Failure experience• Situation awareness• Reaction time• Workload

Collisions Recovery action time since drive-off initiation (s)

Collision time since drive-off initiation (s)

1 close to 120 1202 91 1433 167 Not available4 58 125

Near misses Revovery action time since drive-off initiation (s)

Collision time since drive-off initiation (s)

1 45 1402 very short 75

Source: Chen & Moan, 2003

Source: Grootjen & Neerincx, 2005 Return to Session Directory


The operator’s role

• Level of automation• Failure experience• Situation awareness• Reaction time• Workload overload

Vigilance problems

optimal

underload

task switches

time o

ccup

ied

leve

l of i

nfor

mat

ion

proc

essi

ng

Source: Chen & Moan, 2003



Workload in DP operations

overload

Vigilance problems

optimal

underload

task switches

time o

ccup

ied

leve

l of i

nfor

mat

ion

proc

essi

ng

normal operation

fault in DP system

changingcircumstances



Modes of operation

normal operationLow workload

DP system can operate autonomously

alerted operationNormal workload

Operation as is currently done

emergency situationHigh workload

Operator support



• Operator only monitoring• Workload very low

• DP system takes over operator’s task• Self-monitoring system

• Unattended operation– Operator can perform other tasks– Normal workload

• After fault detection: emergency mode

Modes of operation

normal operation



Modes of operation

alerted operation


• Situation with relatively high risk– Offloading / bad weather

• Self-monitoring system not reliable enough• Similar to current DP operations


• Operator called to DP system• Very high workload

• DP system supports operator in five phases:1. Fault detection2. Fault identification3. Generation of solution strategy4. Implementation of solution strategy5. System’s reaction

Modes of operation

emergency situation



New functions

• To enable three modes of operation:– Self-monitoring for normal operation– Operator support for emergency situation



Self-monitoring

Validation Healthmonitoring

Plant Healthy?

Reference value generator

+

-

Yes

Diagnosis

Knowledgedatabase

Knowledge sources

reference values

residuals

symptoms

sensor readingsinputsignals

No

Process

Source: Grimmelius, 2005



Self-monitoring


Plant Healthy?


+

-

Yes

Diagnosis

Knowledgedatabase

Knowledge sources

reference values

residuals

symptoms


No

Process

Validation:• Sensor self-check• Compare sensors




Self-monitoring


Plant Healthy?


+

-

Yes

Diagnosis

Knowledgedatabase

Knowledge sources

reference values

residuals

symptoms


No

Process

Health monitoring:• Threshold on residuals• Level of threshold determines reliability




Self-monitoring


Plant Healthy?


+

-

Yes

Diagnosis

Knowledgedatabase

Knowledge sources

reference values

residuals

symptoms


No

Process

Reference value generation:• First principle model• Black-box model




Self-monitoring


Plant Healthy?


+

-

Yes

Diagnosis

Knowledgedatabase

Knowledge sources

reference values

residuals

symptoms


No

Process

Health monitoring:• Threshold on residuals• Level of threshold determines reliability

0.0

0.4

0.8

1.2

1.6

0 20 40 60 80 100

time

valu

e

Process [y(t)]

Model [ŷ(t)]residual [r(t)]

threshold

fault detected




Implementation of diagnostics

DP system

ship response

dp computer

monitoringsystem

consistency check

reference based verification

alarm

call operator if suspect behaviour detected

control signals

analyze detected symptoms

operator support

sensors

environment

reference value generator



Operator support

• Presentation of system status– Operator has to ‘familiarize’– Low situation awareness due to unattended operation

• Solving a detected problem– Analyze detected problem to find cause– Generate solution strategies– Predict effect of strategies– Present advice to operator



Requirements and risks

• Fault detection:– Operator to be called in case of any fault– To many false alarms harm functionality

• Quick operator familiarization after fault detection

• Online simulation:– Trade off: accuracy vs. computational power



DP system with diagnostics and support


22MTS DP Conference -- Houston 2007 [email protected] Return to Session Directory

Risk The Road to Eliminating Operator-Related Dynamic Positioning...

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