Cumulative Quantitative Risk Assessment of an Onshore Oil and Gas Industrial Site: A Case Study

Srinivas Sambasivam, et. al.HSE&R, W S Atkins,

Houston, USA

Agenda

• Project Description• Key Challenges• Methodology• Field Survey and GIS Map Development• Consequence and Frequency Analysis• Risk Analysis using Atkins “RiskTool”• Conclusions

Project Description

• Primary Objective – Cumulative QRA of an Oil & Gas Industrial Site.

• Site consists of several Oil & Gas Processing Facilities.• Facilities are Operated by Local, National and International

Oil & Gas Operating Companies.• Other Key Objectives

• Identify Key Risk Drivers • Develop Site Wide Emergency Evacuation Plant• Identify Scenarios that can Escalate Between Individual

Facilities.• Provide Input for Future Land Use Planning

Industrial Site – Major Facilities

Industrial Site – Onshore Wells

Oil Wells (45Nos.)

Industrial Site – Buried Pipelines

Onshore Buried Oil and Gas Pipelines(26Nos.)

Cumulative QRA

• Slug Catcher Facilities• Oil Tank Farm• Condensate Station• Pig Launching /Valve Stations• Number of Onshore Oil Wells• Number of Onshore Oil and Gas Buried Transmission

Pipelines• Number of Oil Gathering Lines Located Onsite

Key Challenges

• Local Resource Availability• Limitations in the Availability of Input Data• Non-Availability of Integrated GIS Map for the Entire

Industrial Site.• Risk Modeling Constraints

• 200 Plus Release Scenarios Resulting in Approximately 4,500 Hazardous Events.

• About 90 Pipeline (Linear) Scenarios.• Variations in Population Distributions Throughout the Site.• Large Area (approximately 22 sq. km) of Study.

Methodology

The QRA was Planned and Executed in the Following Stages:• Data Collection and Review.• Field Survey.• GIS Map Development.• Development of Assumptions Log.• Frequency and Consequence Modeling.• Risk Modeling.• Presentation of Results.• Report Preparation.

Resource Management

COLLABORATIONCOLLABORATION• Collaborative Effort• Teams from

• Houston, USA• Port of Spain, Trinidad• Warrington, UKCOLLABORATIONCOLLABORATION

Project Execution Methodology

INTEGRATION

Field Survey and GIS Map DevelopmentTECHNOLOGY DRIVENTECHNOLOGY DRIVEN

• Use of Geographical Information System (GIS)

• Site Data Captured Using

• Satellite Imagery• Site Survey

Conducted Using Mapping Tools

• Desktop Analysis using ArcGIS Package

TECHNOLOGYTECHNOLOGYDRIVENDRIVEN

Field Survey

Field Survey

Field Survey

Desktop Analysis – GIS Map

Frequency and Consequence AnalysisFrequency Analysis• Parts Count was Performed for the Process Systems.• OIR12 Failure Data was Used to Determine the Release Frequency.• Event Trees Generated Using Various Ignition Models.

Consequence Analysis• The study addressed the following events

• Jet Fires• Pool Fires• Explosions• Flash Fires

• DNV’s PHAST and Atkins “RiskTool” used for Consequence Modeling.

Risk Analysis

INNOVATIONINNOVATION

INNOVATIONINNOVATION• Atkins In-house Developed

QRA Software – “RiskTool”• RiskTool Customized To Model

Up To • 4,500 Hazardous Events, • 14 Different Population Areas

and • 100 Pipe Segments

• Population could be defined in number of ways.

• Risk Analysis Could be Done for Different Weather Conditions

• Can Integrate Consequence Modeling

• Can Import GIS Data• Generates

• Individual Risks• Geographical Risk Contours

Using Surfer Integration• F-N Curves

Start

Enter Grid Definition and Project Description Data

Enter Site-Layout Coordinates

Enter Pipeline Coordinates

Enter Population Data

Input Scenario Data

Input Meteorological Data

Save Project Data

Calculate Conditional Risk

Calculate Individual Risk

Summary

Calculate Societal Risks

Calculate Individual Risk

Transect

Calculate Individual Risk

Grid Results

End

View Outputs

RiskTool P

roject Set-U

p Steps

RiskTool – Input Screen

RiskTool – Site Layout Data

RiskTool – Pipeline Route Data

RiskTool – Site Layout

RiskTool – Scenario Screen

RiskTool – Simple Foot Print Model

RiskTool – Weather Categories

RiskTool – Population Definition at Specific Locations

RiskTool – Population Definition Using Population Distribution Grid

Results – Individual Risk Summary

Indi

vidu

al R

isk

Per A

nnum

Distance in meters

Results – Individual Risk Transect

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

-1000 -900 -800 -700 -600 -500 -400 -300 -200 -100 0 100 200 300 400 500 600 700 800 900 1000

Distance from pipeline (metres)

Ris

k of

rece

ivin

g a

dang

erou

s do

se o

r wor

se (p

er y

ear)

Total risk from all events

1 Rupture fireball and jet fire

2 Rupture jet fire

3 Rupture flash fire (D5)

4 Rupture flash fire (F2)

5 Puncture jet fire

6 Puncture flash fire (D5)

7 Puncture flash fire (F2)

8 Rupture pool fire

9 Puncture pool fire

Indi

vidu

al R

isk

Per A

nnum

Distance from Pipeline in meters

Results – Geographical Risks

Results – Societal Risks

Cumulative Freq

uency Pe

r Ann

um

Number of Fatalities

Conclusions

The QRA Study for the Industrial Site:• Generated the Cumulative Risks for the Entire Site.• Identified Key Risk Drivers to Industrial Site and Offsite

Residential Area.• Identified Potential Scenarios That Can Cause Escalations

Between Different Facilities.• Provide Input for Developing Site Wide Emergency Evacuation

Plan.• Provide Input for Future Land Use Planning.• Provide Recommendations for Risk Reductions to Individual

Operators and Site Management.

Conclusions