SupOps, Haugesund, Norway - 2018.08.08

AUV iCP Results from an integrated Cathodic

Protection Survey of a North Sea Pipeline

Brian Claus, Ph.D., Matthew Kowalczyk, Eng. - OFG

Craig Donald BSc. Dip Eng – ISES Technical Services

Cathodic Protection

Survey

OFG Company OverviewAUV Sensor Development and SupplyAUV Survey Operations

OFG owned and operated “Chercheur”

Hugin1000 - Equipped with HiSAS, MBES, SBP, HiRes

Camera, ADCP, water geochemistry, Self-

compensating magnetometer

OFG/ISES integrated Cathodic Protection

(iCP) system

Operational Support for Third party AUV’s

OFG Self-Compensating Magnetometer (SCM).

Installed in > 20 AUVs

OFG/ISES integrated Cathodic Protection (iCP)

system

Full Service Provider

Project Management

Survey and Mission planning

Data Analysis and Interpretation

Development and Operation of Other

Geophysical Systems

Vulcan CSEM towed array

AUV borne CSEM

ROV borne EM and magnetometer systems (OFG EM

MkIII)

3D Vertical Cable Seismic (VCS)

Towed Array Marine Induced Polarisation System

(MIPS)

Some Recent Interesting Projects

Shell Ocean Discovery XPRIZE

AUV iCP Test Results from a Cathodic

Protection Survey of a North Sea Pipeline

This presentation includes:

1. Overall concept description of the OFG AUV iCP

2. Results of in-field system trials of the OFG AUV iCP system over an operational pipeline in the North Sea. In particular:

• Sensitivity

• Accuracy/Repeatability

• Survey Positioning

• Survey Speed

• Multiple Payload Capability

3. Scenarios for AUV iCP Surveywithin a Pipeline Integrity Management and Inspection Strategy

OFG AUV iCP tests results over North Sea pipeline

• Uses AUV pipe tracking and E-Field system concurrently to accurately locate field gradient measurements relative to pipe

• Current flow through the pipe from Cathodic Protection is then be mapped

• Determines:

- Level of cathodic protection

- Activity of anodes estimate of remaining anode life

- Leakage currents in pipe indictatingfor pipe damage/non-uniformity

The AUV-iCP Concept:integrated Cathodic Protection System

EIVA Simulated Data

Precision NavigationReal-time accuracy of ~2m with HiPAP USBL system

Pipe TrackingReal-time tracking of pipe using HiSAS/MBES provides ~cm level positioning relative to pipe

Field GradientsGradient measurements in 3-axis

Cathodic Current EstimationBy combining these three systems the cathodic current flowing through the pipe can be estimated

dz

dyEx

EyEz

i

dx/dy/dz Ex/Ey/Ez

i

X/Y/Z

The AUV-iCP Concept

• OFG’s AUV Chercheur, a 3000m HUGIN, - Can perform pipe inspection and tracking using MBES,

HiSAS, magnetometer, and photos

• Chercheur now also equipped with the OFG AUV iCPSystem

MBES

AUV-iCP Deployment

Still Photos

AUV iCP Trials over a North Sea Pipeline

Field trial of AUV iCP flights conducted in Q1 2018 on an operational pipeline installed in the North Sea in collaboration with DOF Subsea:

• Measured Field Gradient during multiple survey runs in opposite directions. • ROV CP-DAS survey also performed as a reference survey

• Flown at altitude of 5m above pipeline• iCP data was collected with all usual AUV sensor payloads running, to confirm no

interference• AUV speed of 3.3 knots (~6 km/hr)*

*Note that vessel USBL installation limited speed during the trials.

Nominal AUV survey speed is approximately 7km/hr depending on conditions.

DOF M/V Geocat attending to AUV iCP trials

AUV iCP Sensitivity Test Results

• Variations of approximately 0.01µV/cm were reliably and repeatedly detected.

• The results confirmed during multiple test runs in both directions along pipeline

• The test results indicate that the system is approaching a detection limit TEN times that of any other available field gradient logging system (as per published results).

• UNAMBIGUOUS AND REPEATABLE

AUV iCP Accuracy/Repeatability

Measured FG data showing 2 survey runs in opposite directions

Cross

Vertical

In Line

Standard deviation of difference between measurements in opposite directions:

Et = 0.021µV/cmEx = 0.012µV/cmEy = 0.015µV/cmEz = 0.027µV/cm

- Without correction for position, range, attitude. - Difference is between entire length of pipe that was surveyed in both

directions at the same altitude.

Total

AUV iCP Accuracy/Repeatability

In Line

Total

• OFG AUV iCP Accuracy ~ 0.01 µV/cm

• Standard twin cell CP/FG system +- 1 µV/cm

• Rotating sensor +- 0.1 µV/cm (as per publically available information)

AUV iCP Accuracy/RepeatabilityComparison with other systems:

The grey bar illustrates 0.1µV/cm sensitivity threshold of rotating

sensor system (as published).

Indications would only be observed above sensitivity threshold of

rotating sensor, however they were easily detected using OFG AUV iCP in

x,y & z planes

sensitivity threshold

• The iCP results are not influenced by other on-board sensors e.g. HIPAP, HISAS,

magnetic, acoustic modem, photo mapping, etc.

Allows for concurrent data acquisition from multiple AUV mounted

sensors during pipeline surveys.

• The results of the trials show very good iCP data quality at various ranges from

the pipeline. The distance from the pipeline that the AUV inspection is flown

will not be determined by the iCP, but rather by the limitations of the other

inspection sensors, eg. Camera, Multibeam, Laser Scanner.

AUV Multiple Payload Capability

OFG AUV iCP tests results over North Sea pipelineThis image- MBES bathymetry - Pipeline model from MBES data- Camera imagery draped over pipeline

model

OFG AUV iCP tests results over North Sea pipelineThis image:

- MBES bathymetry - Pipeline model derived from MBES data- Camera imagery draped over pipeline

model

OFG AUV iCP tests results over North Sea pipeline.This image:

- MBES bathymetry - Ex (inline E-field, red line)- Ez (vertical E-field, green line)- AUV track (yellow line)- Pipeline model from MBES data

OFG AUV iCP tests results over North Sea pipelineThis image:

- MBES bathymetry - Pipeline model derived from MBES data- Camera imagery draped over pipeline

model

OFG AUV iCP tests results over North Sea pipelineThis image- MBES bathymetry - Pipeline model from MBES data- Camera imagery draped over pipeline

model

OFG AUV iCP tests results over North Sea pipelineThis image- MBES bathymetry - Pipeline model derived from MBES

data- Camera imagery draped over pipeline

model

OFG AUV iCP tests results over North Sea pipelineThis image:

- MBES bathymetry - Et (E-field total magnitude, multi-

coloured line)- AUV track (yellow line)- Pipeline model from MBES data

Scenarios for AUV iCP Survey within a

Pipeline Integrity Management and

Inspection Strategy

For example; Integrity Management of Submarine Pipeline Systems DnV-RP-F116 Feb 2015, specifies

• Regular inspection on condition of CP system.

• Strategies and plans for pipeline integrity improvement related to cathodic protection

Pipeline Integrity Management Strategy

The AUV iCP system opens the possibility of being able to conduct fast, accurate CP surveys with minimal or no requirement for time-consuming potential contacts

“iCP” means integrated Cathodic Protection; it’s not only about cathodic potential.

Cathodic Potential is measured in mV and is only one of the measurements used to assess how effectively a cathodic protection system is operating.

AUV iCP can give you more information for your Cathodic Protection program.

OFG AUV iCP in a Pipeline Integrity

Management Strategy

Measuring the electrical field (field gradient µV/cm ) around a pipeline with the sensitivity of the AUV iCP system also allows (in addition to the items in previous slide “Excerpt from DNV-RP-F116 Feb 2015”):

- Current density along the pipeline - Disconnected or passivated anodes.

- Anode current output - Identification of anomalies

- Anode activity - Identification of location, direction and magnitude of current flow.

- Estimation of remaining life of the anodes - Current drain (e.g. to platform, well head)

- Identification of areas of active coating damage - Areas exhibiting higher than expected current flow.

Pipeline Integrity Management Strategy

Excerpt from DNV-RP-F116 Feb 2015 AUV iCP Survey

Visual inspection of the external coating condition

Visual inspection of the condition and consumption of the galvanic anodes

Potential measurements of galvanic anodes

Steel-to-electrolyte potential measurements along the pipeline

Potential measurements at any coating damage exposing bare pipe metal

Electric field gradient measurements and current densities in the vicinity of the pipe

Anode current output.

Excellent -> Acceptable -> Poor / Not possible

Measurement of current at anodes

Detection of areas of current flow along the length of the pipeline, including buried and under rock protected

Detection of coating damage under concrete coating and also of areas exposing bare pipe

AUV iCP Electrical Currents

Field Gradients Electrical Currents

Negative are sources:• Anodes

Positive are sinks:• Pipe damage

• Current drain

Distance along pipeline

A D

-1040

-900

-850

-650

mV wrt Ag/AgCl

B C

Protected Design Life – Stable Conditions (e.g. 20 years)

Polar-isation

Depolar-

isationUnder Protected

ROV CP “Stab” vs OFG

AUV iCP Measurements

Lifecycle of Structure

ROV CP “Stab” - Voltage drops and depolarization begins when the anode

mass is nearly consumed….possibly too late to intervene in time.

OFG AUV iCP – Calculate anode currents compute mass and energy remaining and predict anode end-of-

life much earlier!

Protected Design Life – Stable Conditions (e.g. 20 years)

Polar-isation

Depolar-

isationUnder Protected

Potential will start to fall off once majority of anode is consumed

Lifecycle of Structure

Scenario One - Post lay baseline/tie-in CP survey

Scenario Two - Maintenance CP survey

Scenario Three - Intervention CP survey

OFG AUV iCP Usage Scenarios

in a Pipeline Integrity Management Strategy

Rapidly undertaken to confirm the integrity of the pipeline installation.

From a cathodic protection standpoint a number of factors require confirmation. • General Potential level

• Anode connection to pipeline

• Anode damage

• Stinger or laying damage to pipeline

• Unusual or unexpected anode activity

• Areas of current drain.

The OFG AUV iCP system can be used to undertake high speed visual and field gradient measurements.

Other non-CP inspection data can be acquired by the AUV concurrently for out of straightness, free-span, visually identifiable damage, buckling, etc.

Scenario One:

Post lay baseline/tie-in CP survey

Pipelines are typically required to be surveyed either on a prescriptive basis or at a frequency derived from a risk based inspection (RBI) plan, as part of an overall integrity management strategy.

Frequency of inspections generally range from annually to every 5 years, depending on the strategy employed.

Scenario Two:

Maintenance CP survey

• Undertaken to identify any significant changes in the condition of the CP system has occurred since the previous survey.

• To determine if the pipeline cathodic protection system is performing as designed in terms of protection levels and anode performance and anode life.

OFG AUV iCP tests results over North Sea pipeline

Anomaly Based Inspection Example:

OFG AUV iCP used to calculate current

output of each anode over time

𝑀𝑎 =𝐼𝑐𝑚𝑡𝐹8760

𝑢𝜖=273kg

𝑢 = 0.8

𝜖 = 2000𝐴ℎ/𝑘𝑔

𝑡𝑓 = 50𝑦𝑟𝑠

𝐼𝑐𝑚 = 1A

Scenario Two:

Maintenance CP survey

Survey

Year

Current

[A]

Mass Budget

[kg]

0 0 273

1 0.25 271.6313

2 5 244.2563

3 0.5 241.5188

4 0.5 238.7813

5 0.5 236.0438

10 0.5 222.3563

15 0.7 203.1938

20 1 175.8188

25 2 121.0688

27 3 88.21875

29 5 33.46875

30 6 0.61875Premature Consumption!

Identify Increase in activity

Activity above design!

Undertaken if something significant has been identified which could affect the cathodic protection system, for example:

• Pipeline damage• Post anode retrofit survey• Additional connections to pipeline e.g. tie-ins new well, risers, manifolds and structures.

The iCP system can be used to undertake a rapid assessment of the condition of the pipeline after the event has occurred to provide accurate information on the activity of the anodes and identify if there is a correlation between areas of damage and current drain and measure the effects.

Scenario Three:

Intervention CP surveys

The passive, non-contact AUV iCP system allows fast, accurate CP surveys to be conducted:

1. Real-time pipe tracking and inspection using MBES, HISAS, magnetometer and photos

2. Accurately detect and quantify Field Gradient (FG) along a pipeline route at significantly higher speeds than an ROV survey.

3. Detect & quantify pipeline electrical fields to an unprecedented level (variations of ~0.01µV/cm) from which currents (anodes and also damaged areas) can be calculated

4. Signal accuracy was not reduced by either vertical or horizontal standoff distances between the AUV and the pipeline.

5. Gather multiple data sets from other sensors simultaneously without degrading the received FG signals due to system’s operations noise.

6. The system can add significant value in efficiency and cost savings when used as part of an integrated pipeline inspection management strategy.

• Instead of a contact every km this could may be reduced to a handful of selected key point contacts along the entire pipeline route

OFG AUV iCP

Conclusions Based on Field Trials

OFG AUV iCP - AUV Chercheur currently mobilised

to a vessel in the North Sea and will become

available again for pipeline inspection in September

2018.

Questions?

Technical Services Ltd

Europe

ISES Technical Services Limited

1st Floor, Block 7, The Altec Centre

Minto Drive, Altens Industrial Estate

Aberdeen AB12 3LW, Scotland

Tel: 01224 874440

Fax: 01224 872211

Asia Pacific

ISES Technical Services PTE Ltd.

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Tel +65 65 467228

Malaysia

Inspection Survey & Integrity Services Sdn Bhd

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Jln SS15/4G, 47500 Suband Jaya, Selangor, Malaysia

Tel: +6 03 5635 9500 / 9850 / 9750

Fax: +6 03 5635 9655

Web Site: www.ises.techEmail: craig@ises.tech

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Ocean Floor Geophysics Inc.

B108 – 9000 Bill Fox Way

Burnaby, BC

Canada V5J 5J3

E: Matthew.Kowalczyk@OceanFloorGeophysics.com

T: +1-778-654-7781