Presented by Christopher Kitley, Principal Hydrogeologist.

WorleyParsons

Onshore spill modelling to inform contingency planning

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Onshore spill modelling to inform contingency planning

Contents

§  Introduction & background §  Approach §  Modelling techniques §  Case study §  Results §  Innovations and development

Track record: q  Environmental & Social Impact

Assessment (ESIA). q  Contingency planning. q  Infrastructure design. q  Insurance profiles & liability. q  Software development. q  Full field ► Refinery ► Tank

WorleyParsons approach Using our multi-disciplinary consulting & engineering teams q  Phased & risk based approach for

efficient design q  Robust modelling to reduce

uncertainty q  Scalable & transferable to all project

lifecycle assets

Phase 1 Screening

Subsurface migration

Surface spreading

Possible significant spills

Low priority

Phase 2 Numerical Modelling

Catalogue results in OSPS matrix

Phased approach to assess Oil Spill Planning Scenarios (OSPS) for contingency planning

Identification

OSPS Matrix

Contingency planning

Case study: Onshore oil spill modelling to inform contingency planning

Location Development Project scope

§  Arid environment §  Inland wadi systems §  Flat terrain §  Fragile ecosystem §  Surrounding

groundwater users

Large upstream condensate rich: §  >1500 km2

§  >250 gathering wells §  >500 km of pipelines §  CPF, Waste

treatment, §  Reinjection wells §  Fluids: Condensate,

diesel, PW, OBM

§  Front End Engineering & Design (FEED)

§  Contingency planning

§  Numerical modelling to assess spill migration with time

§  No applicable guidance

Case study

Oil spill scenario matrix (OSSM)

Identification of oil spill planning scenarios (OSPS)

Identification: causes / scenarios Likelihood: 100% probability

§  Literature review §  Oil spill planning scenario workshop §  Catalogue of credible oil spill

planning scenarios §  Organised by source, mode of

release & product §  Each populated with pressures,

flows, mitigation measures & socio - environmental risk

Agreed OSSM included 38 top level scenarios & 1,000+ locations

Environmental Impact Factor (EIF) tool

Phase 1 Screening

Risk prioritisation modelling

§  Developed with Statoil.

§  Multi-scenario on-shore tool.

§  Risk management decisions.

§  Prioritisation of sites.

§  Surface and subsurface impact.

§  Maximum surface spreading plotted on GIS → buffer zones.

§  Maximum subsurface migration compared to groundwater elevations.

§  Update oil spill scenario matrix and categorisation of spill scenarios.

Surface spreading

Phase 2 Numerical Modelling

§  Tank & pipeline leak & failure §  Amended flood model and digital elevation model

(DEM)

§  TuFlow 2D surface flow model designed to model shallow flow over complication terrains

§  Amended code for varying fluid properties (density, viscosity, internal eddy friction).

§  Plans and animations of spill migration with time §  Pooling depth and area.

§  Can also model transport in surface water

Phase 2 Numerical Modelling

Subsurface flow

Hydrocarbon spill screening model (HSSM), US EPA/RISC beta version)

Three scenarios:

§  No containment (spill area, duration, volume)

§  Containment (depth, duration)

§  Below ground (flux, duration)

Very sensitive to geological conditions and residual saturation

Worst/best/most likely case used to form up and lower bound estimates

Phase 2 Results Example results:

q  Geographical spread with time

q  Pooling depths

q  Assessment of impacts

q  Re-assessment of impacts

Pipeline failure case

Tank and containment failure Pipeline leak, oblique view with pooling

Results of subsurface modelling

Sensitivity analysis:

q  Variations in pooling depth effects

q  Variations in event durations

q  Upper & lower band cases

Information for contingency planning

Surface spreading Subsurface

Model outputs

§  Graphics of area vs. time. §  Pooling depths. §  Shape files for GIS. §  Depth profiles. §  Upper & lower case envelope. §  Updated OSPS Matrix.

Contingency Planning Information

§  Categorization of spill events. §  Location of worst credible events. §  Response time envelope. §  Areas and volumes of impact. §  Design implications, including:

§  Leak detection requirements. §  Inspection regimes. §  Relocation of camps &

infrastructure. §  Regulatory compliance

Results summary

Response planning

Summary

Innovation q  Project demonstrated that WorleyParsons phased approach worked well. q  Combining multidisciplinary teams of hydrocarbon engineers and environmental

scientists.

q  Adaptation and application of commercially available software q  Robust approach to setting upper and lower bound estimates q  First project of its scope and scale.

q  Development of software & visualization tools Future developments areas:

q  Guidance for standardized approach q  Inclusion of air dispersion modelling to simulate well blow out (screening or detailed)

q  Inclusion of fire hazards (pool fire effects)

q  Inclusion in HAZID workshop q  Project engagement window (ESIA, concept design, detailed design).

Innovation & future developments

Thank you

q  http://www.worleyparsons.com/consultingpractices/ q  http://www.worleyparsons.com/consultingpractices/Documents/Consulting

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