GEOHAZARD IDENTIFICATION AND ASSESSMENT FOR ......geo-hazards along a pipeline, drawing on examples for a gas pipeline in New Zealand. Specifically, the presentation will: • Introduce

Otto Huisman

Arash Gharibi

Sebastian Ruik Beyhaut

ROSEN Integrity Solutions

GEOHAZARD IDENTIFICATION AND ASSESSMENT FOR GAS PIPELINES

• Engineering & Consultancy Company within the ROSEN Group

• Data Management, Integrity & Consulting, Software Services

• Human Power:

• 35 Employees involved in Data & GIS Management

• 50 Software Developers

• 80 Integrity Engineers

ROSEN GROUP: INTEGRITY SOLUTIONS

Technical Support /

Data Services

Software Development

Team

Integrity Engineering

Team

Software Product

Development and

Customization

Post-ILI and

Engineering

Consultancy

PIMS Implementation

Projects and Product

Definition

AGA 2015 Conference · Huisman, Gharibi and Ruik Beyhaut · © ROSEN Group · 30-April-2015

The key objective of this presentation is to illustrate a GIS-based methodology for determining the location and expected significance of

geo-hazards along a pipeline, drawing on examples for a gas pipeline in New Zealand.

Specifically, the presentation will:

• Introduce Geohazards as complex processes

• Discuss risk, threats and consequence

• Illustrate examples of:

1. Determining soil instability

2. Determining aggregate geohazard threats to the pipeline

• Provide some conclusions

OBJECTIVE


• Landslides/mass movement

• Tectonics/seismicity

• Hydrotechnics

• Erosion and upheaval displacement

• Geochemical

• Freezing of unfrozen ground

• Thawing of permafrost terrain

• Unique soil structure

• Desert mechanisms

• Volcanic mechanisms

Source: M. Rizkalla (ed.), 2008. “Pipeline Geo-Environmental Design and Geohazard Management”

GEOHAZARDS INCLUDE…


• Characterised by very high spatial variability

• Often dynamic

• Not as predictable as we would like

• Complex

• etc.

Key question remains: “What (and where) are the risks to my pipeline?”

An ideal ‘answer’ to this question would

consider expert local knowledge (e.g. from

operator staff).

GEOHAZARDS ARE…



GAS PIPELINES: CONSEQUENCES

• Model specified by

MACAW• Implemented in GIS

• Results feed the

consequence parameters of

QPRAM risk model in ROAIMS

ASSESSMENT OF RISKS TO THE PIPELINE

A client-specific risk model should answer the following basic questions:

• Which threats are active?

• Will the active threat result in a leak or a rupture?

• What is the company liability in the event of a failure?


• Central-western part of North Island

• Approx. 390km of gas pipeline (main

backbone only).

• Extremely varied terrain: unique

challenges for field monitoring teams

CASE STUDY: MAJOR GAS OPERATOR IN NEW ZEALAND


Two analyses follow:

1) A methodology for identifying and prioritizing locations of ground

instability along the pipeline for foot patrol and possible remediation

2) A methodology for determining ‘aggregate’ geohazard threats to the

pipeline

For each of these analyses we will need to pay significant attention to:

- Data sources

- Identification of hazards

- Analysis and combination

- Visualisation

CASE STUDY: NEW ZEALAND GAS PIPELINE


1. GROUND INSTABILITY


Semi-automated methodology which makes use of a range of spatial data:

• High resolution imagery

• Digital Elevation Models

• Soil and land cover databases

• Rainfall and rivers data

• Earthquakes and fault lines data

• Supplementary data from client where appropriate and/or available

INPUT DATA

Data Mining (C4.5)

Weight Class Category Weight

0.136 Slope >45 0.154

35-45 0.311

20-35 0.423

10-20 0.063

10> 0.049

0.13 Bending Strain Yes 0.833

No 0.167

0.122 Water Resource Yes 0.833

No 0.167

0.192 Ground Instability (Landslide) Yes 0.833

No 0.167

0.077 Precipitation (Rainfall) >3000 0.489

2000-

3000 0.232

1000-

2000 0.19

>1000 0.089

0.147 Seismic Intencity >7 0.727

5-7 0.2

5> 0.073

0.054 Freezing/Thawing Yes

No

0.082 Erosion High 0.717

Medium 0.217

Low 0.066

0.06 Seismic Frequency ???

ANP + weighted overlay (ArcGIS toolbox)


Combined instability zones:

• Data mining of New Zealand Land

Resource Inventory (LRI)

• Spatial model using soil type, rainfall and Digital Elevation Model (DEM)

• Total extent of occurrence (max area)

GROUND INSTABILITY AREAS

Erosion form name

Debris avalanche

Earthflow

Earth slip

Mudflow

Soil slip

Rockfall

Slump


COMBINING GEOHAZARDS


• Reclassification and combination of available data

from multiple data sources

• Use of modelling tools to derive weightings from best practice documents and published sources on

geotechnical risk.

• Additional threat drivers/geohazards can be added

as necessary.

INPUT DATA

Class

Slope

Ground Instability

Precipitation

(Rainfall)

Seismic Intensity

Freezing/Thawing

Erosion


MODEL GEOHAZARDS TO IDENTIFY ‘AGGREGATE’ VALUE: INPUT DATA

Slope is made up of thenational New Zealand DEMfile with a resolution of 11meters

Ground instability is (partially)derived from analysis onnational Land ResourceInformation (LRI),

Rainfall dataset is made upof the average rain fall of thelast 25 years of NewZealand.

Seismic intensity is made up ofEarthquake dataset of last 30 years.

Impact zone of the earthquakes iscalculated based on the studies onregistered hazard zones.

Freezing and Thawing iscalculated based on clusteredaverage temperature of all thedays of the last 30 years.

• Each hazard is assigned a weight

• Each category within the hazard is

also assigned a weight

• These can be derived from data

mining existing failure reports or

databases

• Aim is to get domain expert input

into weighting to assess the relative importance of each hazard within a

give zone or area.

ESTABLISHING WEIGHTS FOR COMBINING GEOHAZARD THREATS


0.175 Slope >45 0.154

35-45 0.311

20-35 0.423

10-20 0.063

10> 0.049

0.139 Proximity to water Yes 0.833

No 0.167

0.203 Ground Instability Yes 0.833

No 0.167

0.098 Precipitation >3000 0.489

2000-3000 0.232

1000-2000 0.19

>1000 0.089

0.195 Seismic Intensity >7 0.727

5-7 0.2

5> 0.073

0.075 Freezing/Thawing Yes 0.901

No 0.099


Medium 0.217

Low 0.066


Use of Analytic Network Processing methodology (ANP) to deal with complexity: categories within each

class are treated separately

Each class is assigned a rank, and a

decision matrix is generated, where

the resulting weights are based upon the principal eigenvector

Mapping and classification can be used for visualizing results...

ESTABLISHING WEIGHTS FOR COMBINING GEOHAZARD THREATS


0.175 Slope >45 0.154

35-45 0.311

20-35 0.423

10-20 0.063

10> 0.049

0.139 Proximity to water Yes 0.833

No 0.167

0.203 Ground Instability Yes 0.833

No 0.167

0.098 Precipitation >3000 0.489

2000-3000 0.232

1000-2000 0.19

>1000 0.089

0.195 Seismic Intensity >7 0.727

5-7 0.2

5> 0.073

0.075 Freezing/Thawing Yes 0.901

No 0.099


Medium 0.217

Low 0.066


AGGREGATE GEOTECHNICAL HAZARD

Areas of

concern/ prioirity

for combinedgeohazards

Resolution: ~400m grid cell


96% of bending strain

segments found to lie within either ‘red’ or

‘orange’ geohazard

zones

EVALUATION OF RESULTS: OVERLAY WITH BENDING STRAIN


• Geohazards represent complex threats to a pipeline

system

• ‘Good’ data required for their accurate assessment, but a good methodology is also essential

• New approaches in handling complex processes can be deployed ‘in a spatial context’

• GIS modelling approaches can provide useful inputs into risk assessment process, but also as ‘screening’ for more

detailed assessment and mitigations.

CONCLUSION


www.rosen-group.com

THANK YOU FOR JOINING

THIS PRESENTATION.

Documents

GEOHAZARD IDENTIFICATION AND ASSESSMENT FOR ......geo-hazards along a pipeline, drawing on examples for a gas pipeline in New Zealand. Specifically, the presentation will: • Introduce