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Safeti Offshore An Introduction


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Det Norske Veritas AS. All rights reserved.

Background

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Over the years, DNV has developed a number of tools for safety analysis ofOffshore installations

Offshore Hazard and Risk Analysis Toolkit (OHRAT)

- First version released in 1992 in direct response to Piper Alpha disaster- Joint industry project with numerous Operators, Consultants and EPCs

Neptune

- The OHRAT concept taken into Microsoft Windows environment (1999)

Spreadsheet models (e.g. SOQRATES) (2005+)

Phast also used for Offshore consequences

All these tools have their own respective benefits and drawbacks

As a result, in 2009 DNV started discussing a new tool to harness our Offshoreexperience so far and build a new tool for the future

Welcome to Safeti Offshore!


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Safeti Offshore

A joint collaboration involving significant investment between:

- DNV Consulting, providing their Offshore QRA and domain experience

- DNV Software, delivering software engineering and mathematical modelling expertise

Design discussions during 2009-2010

Project and coding kick-off January 2011, starting with Proof of Concept

First internal release planned for end-2012, plus regular interim releases

Key project goals:- Develop an integrated and uniform approach to Offshore QRA based upon international

standards such as ISO 17776 and NORSOK Z013

- Integration of separate QRA models within one common software tool

- Support risk management throughout the lifecycle of an installation from planning to

decommissioning

- Provision of a standardised tool building on the well-established Phast architecture

- Benefit from software economies of scale

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Whats new in Safeti Offshore?

Safeti Offshore incorporates significant new technology compared with currentSafeti (Phast Risk)

Offshore asset hierarchy

Automatic release case generation (subject to user defined rules)

3-D graphical input and viewer

Powerful data input grid

New mathematical modelling, including:

- Improved discharge modelling, allowing for safety systems:

- Detection, isolation and blowdown

- Integration of DNV Express, a probabilistic model for module explosions

- New compartment fire model taking into account module geometry and flame development- Subsea releases

- Escalation modelling

Plus everything else that Safeti currently contains

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Safeti Offshore Basic Workflow

Assets tab:

Define Installation Areas

Define Safety Barriers, Walls and Decks

Define Escape Routes

Define Structural Elements

Process Tab:

Define Isolatable Sections

Define Equipment items

Define Process Case options

Define Risers & Pipelines

Define Wellgroups

Generate Leak Locations (Scenarios)and Cases (Safety Systems) for eachsection

Add User Defined Scenarios

Assign Explosion Targets &Vulnerabilities

Define other data:

Materials

Weathers

Worker population

Then perform the calculations: Inventory volume

Leak frequencies

Consequences

Risk

Review results and perform sensitivityanalysis

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Building a 3D representation of the QRA (1)

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2. Then add StructuralElements

1. First add your

installation areas (in termsof cuboids)


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3. Next add physical

safety barriers, such aswalls and decks. Thesewill be used later asexplosion targets for yourLeak Locations

(scenarios)

4. Add isolatable sectionswith associated equipment,valves and pipework


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Until finally the full 3D model is complete including:

- Risers

- Pipelines

- Escapeways

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New Data Input Grid

Allows import from other systems and manipulation of data in bulk grid format

Comparable with Excel cells supports Copy and Paste from Excel

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Data can begrouped accordingto your specificrequirements


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New Time Varying Discharge Model

Takes account of time dependent release characteristics together with incorporatedSafety Systems, for example:

- Detection

- Isolation

- Blowdown

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Leak

LocationIS1-G

1.000E-14

1.000E-13

1.000E-12

1.000E-11

1.000E-10

1.000E-09

1.000E-08

1.000E-07

1.000E-06

1.000E-05

1.000E-04

1.000E-03

1.000E-02

1.000E-01

1.000E+00

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 1400.0 1600.0 1800.0 2000.0

Probability

Time [s]

Cumulative Probability of Ignition

Small (main)

Medium (main)

Lare (main)

Leak

LocationIS1-G!E"#l$%i$n &are'

1.000E-06

1.000E-05

1.000E-04

1.000E-03

1.000E-02

1.000E-01

1.000E+00

0.0000 0.2000 0.4000 0.6000 0.8000 1.0000 1.2000

Probability

(givenI

gnition)

Pressure [bar]

Aggregated Exceedance Probability vs Explosion verpressure

Small (main)

Medium (main)

Lare (main)

New probabilistic explosion model - EXPRESS

EXPRESS is used to calculate the following:

- Flammable cloud dispersion in source module (cloud volume)

- Detection, Ignition and Explosion probabilities

- Explosion Overpressure Exceedance Curves (at each defined target)

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New Compartment Fire Model

Bridges the gap between existing Phastfire models and CFD

Builds upon the existing Phast fire

models by combining them in new ways

Fires begin in the source module

Fires allowed to develop and escalatebeyond the source module:

- Overall volume of the flame is conservedand spread over the platform inaccordance with layout and geometry

Also handles scenario where fire walls

are damaged or removed by initialexplosion prior to fire

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New Compartment Fire Model An example (1)

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Wind

Geometry layout and setup consists of definingvarious platform elements, for example

Horizontal decks

Vertical walls

Partial walls (eitherrestricted height or width)Fire start location

Solid fire walls


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Spill rate: 3.5kg/s

Spill rate: 1.5kg/s

Pool fire confined to the sourcemodule and modelled as cone

Flame grows in size. Spreads toadjacent module (represented as

cuboid) and outside the platform(represented as cylinders)


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Spill rate: 11.0kg/s

Spill rate: 16.0kg/s

Fire in adjacent module now grows larger

and it extends outside platform in multiplelocations. External wind effects now tilt theexternal flames.

Fire now at maximum size inside the module. Firemodel considers transition of burning process from

fuel controlled to ventilation controlled inside themodule. This is shown as a similar fire size insidethe module (despite the increased spill rate) coupledwith increased external fires


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Risk Results

Detailed risk results produced for each potential outcome

Work on-going to develop sophisticated reporting mechanisms

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Overview of Typical Results (1)

Results related to frequency, consequence and risk results

Frequency results

- Generally frequencies per year for the specific end events

- Grouped frequencies per year according to high-level hazard categories- Grouped frequencies by area of the platform

Consequence results

- Discharge, release rate data (by event scenario and safety system) including flow rate,

duration- Explosion results: EXPRESS / DAL detailed results; overpressure / impact at targets;

escalation result

- Fire results: fire and radiation extent; impact at targets; escalation result

- Toxic results: dispersion extent; impact at targets

- Smoke results: dispersion extent; impact at targets

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Overview of Typical Results (2)

Personnel risk

- Number of fatalities by area, by event, by immediate / escape / evacuation

- LSIR (Location Specific Individual Risk). The frequency with which a person located in aparticular area would become fatalities. This can be calculated on the assumption that a

person is constantly present in an area, i.e. 365 days per year and 24 hours per day.- Maybe LSIR contours not so relevant for offshore. But areas may be colour coded according to LSIR

results similar to LSIR contours

- NOTE LSIR is key as all other calculations use it as basis

- Potential loss of life (PLL) per area and for the entire facility

- FAR (Fatal accident rate), for personnel inside the plant. The fatal accident rate (FAR) is theexpected number of fatalities per 108 hours of exposure:

- FAR value for a defined group of personnel e.g. process operators.

- FAR value for one specific area (Area FAR)

- IRPA (Individual Risk per Annum). The probability of a given individual becoming a fatality in

a year as a result of their work associated with an installation or group of installations.Positional IRPA

- FN curves, Societal risk or Aggregate risk

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Sample Facility Geometry - FPSO

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Sample Facility Geometry - FPSO

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Sample Facility Geometry Jacket Platform

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Sample Facility Geometry Semi-submersible

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Sample Facility Geometry Semi-submersible

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Towards the Future - Timeline

Safeti Offshore initial development project will run until end of 2012

Initial project use within DNV from early 2013

Timescales for commercialisation and rollout to our existing Phast Risk customers is

not yet defined:- We would greatly welcome your feedback on this topic

If anyone has specific needs for their own Offshore QRA analysis, now is a goodtime to talk with us. We have the possibility to include:

- New calculation models

- Specific features and customisations

- Additional reporting mechanisms

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