Deepwater Meets The Shelf.

Paul StevensonRegional ManagerFugro Structural MonitoringSeptember 9, 2009

Deepwater Meets The Shelf

Production from Deepwater Developments rely on the existing older infrastructure on the Shelf to come to Market.

Expanding development in deepwater will inevitable put more strain on the existing older infrastructure.

GOM Pipeline Routing

Safeguard Structural Integrity of Shelf Platforms

There is a growing need to further safeguard the structural integrity of the shelf platforms.

This is done by regular inspection on typically 5 year interval but can be longer.

Current GOM Inspection Approach

Majority of platforms are on a five year underwater inspection interval alternating Level II - primarily general visual inspection (GVI) Level III - GVI and close visual inspection (selected

nodes and some FMD Flooded Member Detection)

MMS administers this process following Federal law 30 CFR 250.901 which generally adheres to API RP 2A guidelines

Underwater inspection of platforms is primarily performed by divers

What Happens to Production When a Hurricane Comes Through The GOM

Similarly an inspection process is enforced after an event such as a hurricane. Production is shut-in (stopped at source) Hurricane Passes Topside Visual inspection is carried out Assessment done to establish what further level of

inspection is required, and carried out. Pursuant to 30 CFR 250.919 which generally adheres to API

RP 2A guidelines and more recently extracts from API BUL 2HINS

Production is started if deemed safe to do so.

Which Platforms Are Selected to be Inspected

The Post Hurricane Inspections

Approximately 3400 platform Inspections were required and

has taken many years to complete

Why so long?

Mainly Due to Lack of Resources After Hurricanes

GOM Workboat DayRatesWorkBoat Survey of 34 Offshore Vessel Supply Companies

1

1.5

2

2.5

3

3.5

4

20-Sep-04 9-Nov-04 29-Dec-04 17-Feb-05 8-Apr-05 28-May-05 17-Jul-05 5-Sep-05 25-Oct-05 14-Dec-05 2-Feb-06

Nor

mal

ized

US

$ /

Day

70

75

80

85

90

95

100

% F

leet

Util

izat

ion

AHTS Dayrate 200' Supply Boat Dayrate 125' Crew Boat Dayrate

AHTS Utilization 200' Supply Boat Utilization 125' Crew Boat Utilization

AHTS Quadrupled in Price Since Nov 04 Average Price 15 to 60 $K

Hurricane Dennis Shut-in

Katrina Shut-in

Supply and Crew Boats Doubled in Price Since Nov 04 Average cost 7 to 10 $K

Hurricane Katrina/Hurricane Rita/Hurricane Wilma Shut-in

Utilization Maxed

GOM Oil and Gas Shut-in

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

11/9/2004 2/17/2005 5/28/2005 9/5/2005 12/14/2005 3/24/2006 7/2/2006

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

Oil, BOPD Shut-in Gas, MMCF/D Shut-In

Katrina Shut-inHurricane Dennis Shut-in

Hurricane Katrina/Hurricane Rita

Shut-in

Hurricane Katrina/Hurricane

Rita/Hurricane Wilma Shut-in

22%

14%

                                                                                                   

What Happened To Production

What Can we do to Ease The Inspection Burden

World Trends to Inspection:

Move away from detailed weld inspection and towards less invasive methods (e.g., FMD)

A stronger focus on the overall Structural integrity Acceptance that some level of damage can be shown to

be permissible Structural Integrity Response monitoring as an

alternative to subsea inspection

What is Structural Integrity Response Monitoring

Structural Integrity Response Monitoring is considered to be the process whereby:

Response characteristics of a structure are measured (either continuously or at regular intervals)

With a view to comparing the measured characteristics with a previously measured baseline or trend.

Structural Response Characteristics

Mode Shapes, Natural Frequencies

Offshore Fixed Jacket Structural Response Characteristics

0 0.5 1 1.510

-4

10-3

10-2

10-1

100

Frequency (Hz)

Pow

er S

pect

ral D

ensi

ty

Typical Acceleration Power Spectrum

Sway Mode

Torsion Mode

Higher Order Modes

DominantWave

Excitation

Sway Mode 1st Torsional Mode

2nd Torsional Mode2nd Sway Mode

How do we Assess the Structural Response Characteristics

Sensors on structureFor an offshore fixed platform it can be

something as simple as a vibration sensor

Acquire Structural dynamic data Perform Structural Analysis Compare results with model or Trend

The Basis to Structural Integrity Monitoring

The frequency response of the structure is determined from the stiffness and mass properties of the structure. In the over simplified form:

M

kf 2

1

where k is the stiffness of the ‘spring’ returning the mass, M, to its equilibrium position.

On a platform, k is a measure of both jacket and foundation stiffness.

•Single Degree of Freedom Oscillator

How Does Structural Response Monitoring Work?

Change in stiffness leads to a detectable shift in Change in stiffness leads to a detectable shift in response frequency of the platform.response frequency of the platform.

Structures loaded periodically by wave loading. Structures loaded periodically by wave loading. (Excitation force)(Excitation force)

Accelerometers detect movement on topsides. Accelerometers detect movement on topsides. (response to excitation force)(response to excitation force)

PC collects and processes data to show PC collects and processes data to show frequencies of dynamic response of structure.frequencies of dynamic response of structure.

Some Examples of Where Response Measurements Are Used?

One of the oldest systems is installed on the CNR’s (One of the oldest systems is installed on the CNR’s (formally formally Chevron’sChevron’s) Ninian Southern Platform in the North Sea in 1986. ) Ninian Southern Platform in the North Sea in 1986.

The most recent Fugro OLM systems :The most recent Fugro OLM systems : ExxonMobil Thames field (4 platforms)ExxonMobil Thames field (4 platforms) Statoil’s Kvitbiorn PlatformStatoil’s Kvitbiorn Platform Chevron’s Benguela Belize Compliant Tower offshore West Africa Chevron’s Benguela Belize Compliant Tower offshore West Africa

(about to be commissioned).(about to be commissioned). ExxonMobil Thebaud Platform (Sable Island)ExxonMobil Thebaud Platform (Sable Island) CNR’s East EspoirCNR’s East Espoir Pemex AKAL H and C1 (includes shallow gas and seismic Pemex AKAL H and C1 (includes shallow gas and seismic

monitoring)monitoring)

Other OLM systems previously in the North Sea: Shell’s Other OLM systems previously in the North Sea: Shell’s Goldeneye, Tern A, BP’s Magnus, Forties Alpha and Bravo, Goldeneye, Tern A, BP’s Magnus, Forties Alpha and Bravo, Total’s MCP01, Statoil’s Gulfaks, Oseberg A and C, 16/11 ETotal’s MCP01, Statoil’s Gulfaks, Oseberg A and C, 16/11 E

Fugro have performed over 200 of these measurements worldwideFugro have performed over 200 of these measurements worldwide

Advanced Eigen Analysis

Combining the advanced computer structural modeling

with the advances in measurement technologies

Major Benefits of Response Measurements

To reduce periodic sub-sea structural inspection.To reduce periodic sub-sea structural inspection. Either by extending the time between regular inspection or by omission after Either by extending the time between regular inspection or by omission after

an event. an event.

Instant detection of subsea structural failure after seismic event, storms, Instant detection of subsea structural failure after seismic event, storms, hurricanes, impact etchurricanes, impact etc Allow the operator to focus on damaged platforms. Allow the operator to focus on damaged platforms.

Reduce the time the structure is at risk to a failed member.Reduce the time the structure is at risk to a failed member. Hence reduce the probability of catastrophic failure. Hence reduce the probability of catastrophic failure.

Assess the effectiveness of a repair to platformAssess the effectiveness of a repair to platform Show that the platform stiffness has returned to an acceptable levelShow that the platform stiffness has returned to an acceptable level

Tune Structural Model, for assessing effect of modifications and damage to the Tune Structural Model, for assessing effect of modifications and damage to the structure.structure.

Risk-based inspection methods can demonstrate the influence of the damage on Risk-based inspection methods can demonstrate the influence of the damage on a structure.a structure.

Secondary Benefits

It can be used as an alarm system on unmanned platforms in the event of a collision with a vessel.

Where marine growth is a problem the system may show a significant change in structural response.

Ensuring no further degradation in robustness during platform abandonment

Case Study of Subsea Structural Failure

4-legged Jacket 100 meters of water depth Long term OLM system Inverted K configuration

On-line Detection of Structural Failure

4-legged Platform with permanent On-Line Structural Integrity Monitoring system onboard

B4 EW

North

F4 EW

F4 NS

B2 NSF2 NS

B4 NS

F2 EW

B2 EW

Sudden Change in Natural Frequency

Dec2006 Jan2007 Feb20070.36

0.365

0.37

0.375

0.38

0.385

0.39

0.395

0.4

Date

Sta

tistics (

Hz)

Results Data

NS1-F4NS

AC.FREQUENCY

Dec2006 Jan2007 Feb20070.36

0.365

0.37

0.375

0.38

0.385

0.39

0.395

0.4

Date

Sta

tistics (

Hz)

Results Data

EW1-F4EW

AC.FREQUENCY

Dec2006 Jan2007 Feb20070.495

0.5

0.505

0.51

0.515

0.52

0.525

0.53

0.535

Date

Sta

tistics (

Hz)

Results Data

TOR1-F4NS

AC.FREQUENCY

North

F4 EW

F4 NS

B2 NSF2 NS

B4 NS

F2 EW

B4 EW

B2 EW

Sudden change in NS frequency

Sudden change in Torsional frequency

NO Change in EW

Summary of Change

Natural Frequency

Change

NS1 -2.8%

EW1 No Detectable change

TOR1 -1.2%

Comparison of Measured With Model Analysis

Frequency NS1(%)

EW1(%)

TOR1(%)

Observed 2.8 0.0 1.2

Possible brace severance with high probability

MD41 2.31 0.57 0.88

MH21 2.46 1.00 1.26

MH41 2.46 1.00 1.26

Possible brace severance but with less probability

MB41 1.48 0.19 0.53

MD21 1.76 0.22 0.50

Natural Frequencies After Repair

03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 01 02 03

0.36

0.37

0.38

NS

1 (

Hz)

Natural Frequency Values

28-day mean LoLo

Guide

Absolute Low er Limit

Hourly

24-hour Mean

03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 01 02 03

0.37

0.38

0.39

EW

1 (

Hz)

28-day mean

LoLo

Guide

Absolute Low er Limit

03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 01 02 03

0.495

0.5

0.505

0.51

0.515

Date: Sep - Oct 2007

TO

R1 (

Hz)

28-day mean

LoLo

Guide

Absolute Low er Limit

Major Benefits of Response Measurements

To reduce periodic sub-sea structural inspection.To reduce periodic sub-sea structural inspection. Either by extending the time between regular inspection or by Either by extending the time between regular inspection or by

omission after an event. omission after an event.

Instant detection of subsea structural failure after seismic Instant detection of subsea structural failure after seismic event, storms, hurricanes, impact etcevent, storms, hurricanes, impact etc

Allow the operator to focus on damaged platforms. Allow the operator to focus on damaged platforms.

Reduce the time the structure is at risk to a failed member.Reduce the time the structure is at risk to a failed member. Hence reduce the probability of catastrophic failure. Hence reduce the probability of catastrophic failure.

Assess the effectiveness of a repair to platformAssess the effectiveness of a repair to platform Show that the platform stiffness has returned to an acceptable Show that the platform stiffness has returned to an acceptable

levellevel

Tune Structural Model, for assessing effect of modifications Tune Structural Model, for assessing effect of modifications and damage to the structure.and damage to the structure.

Consideration

Consideration should be given to applying this technology to the 40 or so shelf installations that the deepwater production relies on.

THE END

Thank you