18 Gulbraar BPT_Tekna-ProcessSafety Rev01F_ConfPaper

7/27/2019 18 Gulbraar BPT_Tekna-ProcessSafety Rev01F_ConfPaper

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Over ressure Protection of Oi l & GasProduction Facilit ies (Inlet Arrangements)

Design av innlpsarrangement(choke kollaps/feilpning) ved brukav integrerte simuleringsverkty.

Billington Process Technology AS

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rne yrvang u raar Tekna, Prosessikkerhet Olje og Gass,2.-3. Nov. 2011, Bergen

Email:[email protected] Phone:+4767569990

VisitingAddress: Lkketangen20,Sandvika

COMPANY PRESENTATION

Since 1998, BPT core business is to provide so lu tion focused ver i ficaton andsuppo rt services as an independan t 3 rd par ty p rocess spec ial is t t o asset

owners and/or proprietory process owners.

Our business is conducted by combining component and system design know-how, f ield exper ience with st ructured use of both r igorous sta tic and dynamicprocess simulation models.

BPT hol ds ow n s oftw are l icenses for steady s tate as w el l as dynami csimulations.: HYSYS & OLGA (Including HYSYS options like Crude, Amines,


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Upstream Dynamics,.Olga-Hysys link etc.).

Models are as far aspossible validated against f ield data.

The company has implemented a Quality Assurance System according to ISO9001:2000.

BPT is certified to the Achilles Joint Qualification System underID No. 26845 for suppliers to the oil & gas industry.


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Life cycle simulations


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Overpressure Protection of Oil & Gas Production Facilit ies(Inlet Arrangements)

BPT Utilizes Integrated Dynamic Multiphase (OLGA (1))and Process (HYSYS (2)) to design Oil & Gas ProductionFacilities for the so called inadvertent opening of inletblock valves with production choke fully open andchoke collapse scenarios.

Fail open & Choke collapse Projects by BPT:

Statoils sgard A & Bincl the Morvin tie-in & theSmrbukk Sr tie-in

Picture of sgard B: With courtesyfrom Statoil ASA

Statoils Kristin incl theTyrihans tie-in

Enis Goliat

Enis Marulk tie-in toStatoils Norne FPSO

Statoils Huldra

Totals HildStatoils Valemon

Statoils Skuld tie-in toStatoils Norne FPSO

Statoils Visund Srtie-into Gullfaks C


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(1) OLGA :

Dynamic multiphase flowproduct of SPT Group

(2) HYSYS :

Aspen HYSYS Dynam ics,by AspenTech


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Benefits vs Plant Regularity &

Integrity

Extend operational limits

(raise flowline PSHH)? Remove interlocks?

Simplify procedures?

Reduce maintenance requirements?

Larger chokes/less change-outs?

ll ll i i

By using dynamic simulations in the design ofoverpressure protection systems, a betterutilization of existing as well as newinstallations can be achieved

PlantRegularity/

Production

(ii) Design based on tooconservative model

(i) Design based on improvedmodel assumptions, by use ofrigorous dynamic simulations=> Robust / Conventionalsecondary pressure protectionsystem

ll ll i i

Potential for...

Less flowline trips

Less plannedmaintenance

(ii)

(i)


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Plant integrityA plants minimum spec.

=> Complex / Instrumentedsecondary pressure protectionsystem.

Quicker start-up aftertrip

Introduction - Overpressure Protection

Overpressure protection of inlet arrangement in a process plant is achallenging design task due to the complex dynamic multiphasephenomena often occuring from incoming pipelines

Key standards:FlareTip

Typical Inlet Arrangement:

Norsok P-100 ++

Example:

Oil&Gas offshoreproductionfacility with longdistance subseatie-backs

InletSeparatorRiser

BlockValve

Riserhang-off

Production

Choke

PSV

InletManifolds

FlareK.O.Drum

TestSeparator

PSV

HV

HV


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TemplatesFlowlines

Wells

Risers

Sub sea valves(Wing, master and choke)


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Introduction - Overpressure Protection

Operators Needs:Safe platform operations without restricting Production orPlant OperabilityOptimum utilization of the facility

Static approaches have in various cases shown to be unpredictable,resulting in safety hazards

Stand alone multiphase (OLGA) simulations have been used by manyoperators with success to establish a safe and operable system

The linked multiphase & process simulations bring additional benefitsinto the design:

more realistic design cases can be evaluated Extend operational limits(raise flowline PSHH)?


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Improved understanding is gained

This again leads to a safer design, and abetter utilization of the facility

Remove interlocks? Simplify procedures?

Reduce maintenance requirements?


Allow for choke collapse in design?

Overpressure Protection of process inlets

PSV

FlareTip

Aim:

To keep the flow ratefrom a shut-inpipeline, uponaccidental opening ofInadvertent

Example 1: Protection of process equipment frompressure overload resulting from Inadvertent opening ofinlet block valve with production choke fully open

InletSeparatorRiser

Block

ValveRiser

hang-off

Productionfrom wellsor flowlines

ProductionChoke

InletManifolds

FlareK.O.Drum

TestSeparator

PSV

HV

HV

the blocking valve,below an acceptablevalue

Means:

Restrict settle-outpressure in pipelineupon shut-in

Result:

(1st error)

100%open

Flare header


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Conventionalpressure protectionaccording to API

What is the flowline process conditions at the start of the incident?

Well: Full shut-in pressure

Flowline: Full shut-in pressure, or restricted settle-out pressure in pipeline uponshut-in ?


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Overpressure Protection of process inlets

PSV

FlareTip

Aim:

To keep the flow ratefrom a shut-inpipeline, upontopside choke

Collapsing /

Sudden increase

Example 2: Protection of process equipment frompressure overload resulting from topside chokecollapse

InletSeparatorRiser

BlockValve

Riserhang-off

Productionfrom wellsor flowlines

ProductionChoke

InletManifolds

FlareK.O.Drum

TestSeparator

PSV

HV

HV

collapse, below anacceptable value

Means:

Choke configuration(1x100%, 2x50%..)

Restrict settle-outpressure in pipelineupon shut-in

in capacity

(1st error)100%open

Flare header


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Result:

Conventionalpressure protectionaccording to API

What is the flowline process conditions at the start of the incident?Normal production? Normal start-up? Choke position at time of collapse

Picture reference:Cage Collapse, Safety aspects of TC cage collapse and impact testing,Presentation by Mokveld at TEKNA Process Safety Conference, Bergen, 2010.

Basic requirements

Codes and standards for vessels and pipelinesPressure directive for vessels: P < 1.1 x design pressure, brief surge allowed

ASME ANSI B31.3 for i es: 1.3 x desi n ressure

Conventional design of relief-systemsAPI Std 521 (identical ISO 23251)

Sizing of secondary barrier, PSV and associated flare system Protection against any single failure, e.g. mal operation of valves

API RP 14C

To define necessar rimar and secondar barriers


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ISO 10418 replaces API RP 14C for new systems

Choose a conventional solution according to a strict interpretation of APIpractice ?


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Basic requirementsAPI Std 521, 5th Edition, 2007 (ISO23251)5.22 Dynamic simulation:

..can be used to calculate transientpressure increases

..can be used to calculate relief rates from

The user should be aware of the underlyingassumptions that are built into the dynamicsimulation software code and how they affect

individual relief devices (PSVs)

Conventional methods for calculating reliefloads are generally conservative and canlead to overly sized relief- and flare systemdesigns.

Dynamic simulations provides an alternativemethod to better define the relief load andim roves the understandin of what ha ens

At steady-state conditions, the dynamicmodel shall closely match the steady-statemodel

If dynamic simulation is used, sensitivityanalyses shall be performed to assessfactors such as the effect of pressure-reliefdevices with excess capacity, the action of


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during relief

If the physical phenomena are not wellunderstood, the dynamic simulation modelshall include conservative assumptions.

, ,

Basic requirementsAPI Std 521, 5th Edition, 2007 (ISO23251)5.22 Dynamic simulation:

..can be used to calculate transientpressure increases

..can be used to calculate relief rates from

The user should be aware of the underlyingassumptions that are built into the dynamicsimulation software code and how they affect

Degree of conservative assumptions mayimpact number of sensitivity cases that arerequired. Key parameters to define:

individual relief devices (PSVs)

Conventional methods for calculating reliefloads are generally conservative and can

lead to overly sized relief- and flare systemdesigns.

Dynamic simulations provides an alternativemethod to better define the relief load andim roves the understandin of what ha ens

At steady-state conditions, the dynamicmodel shall closely match the steady-statemodel

If dynamic simulation is used, sensitivityanalyses shall be performed to assessfactors such as the effect of pressure-reliefdevices with excess capacity, the action of

Worst case normal operating conditions

Well production (reservoir cond, PI,..)

Flowline conditions (P, T, Holdup)

Separator conditions (P, T, Level)

Valve initial posistions & actions

Backgound production

Piping P-Flow relation and volumes


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during relief

If the physical phenomena are not wellunderstood, the dynamic simulation modelshall include conservative assumptions.

, , Valve capacity & characteristics


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Basic requirementsNorsok P-100, Edit ion 3, Feb 2010)

16.2.2 Choke valve collapse:

.. The relieving rate and the resultingpressure build-up in case of choke collapseshall be determined. The relieving capacity

.determining the required relieving rate, thehighest realistic GOR and pressure in flow-line/riser shall be used. A dynamic analysismay be required to determine these effects.


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Method - Overpressure Protection of process inlets

Utilizing Integrated Dynamic Multiphase (OLGA (1)) and Process(HYSYS (2)) to design Oil & Gas Production Facilities for inadvertentopening of inlet block valves with production choke fully open andchoke collapse scenarios.

Statoils Kristin

(1) OLGA :

Dynamic multiphase flow


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Statoils sgard B

product of SPT Group

(2) HYSYS :

Aspen HYSYS Dynam ics ,by AspenTech

Pictures: With courtesy from Statoil


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OLGA - Multiphase flow simulator

Dynamic simulator designed forflow in wells and pipelines

Appears to be the de-factoindustr standard for simulationof transient multiphase flow

Engineering

Operation


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Figure: OLGA application areas and users (With courtesy from SPT Group)

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OLGA/HYSYSLinkBy AspenTech and SPT Group

A dynamic user operationextension withinHYSYS Dynamics

Process parametersexchanged

Pressure, Temperature, Phase mass flow rates, Phase fractionsdP/dF: Change of pressure with change in phase flow

Fluid definitions OLGA uses PVT tables com ositional OLGA not used in thiswork Use the same set of pseudo components and apply the sameequation of state/fluid definitions in both OLGA and HYSYS.A HYSYS Reference stream defines compositional split from

phase fractions, P & T as received from OLGA (Gas, Liquid &Water)

Time Synchronization OLGA and HYSYS integrate differently using potentially differenttime steps and integration techniques.


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OLGA time step must be an integer multiple of HYSYS steps. The solved pressure-flow conditions from OLGA are notimmediately enforced upon the HYSYS model but instead HYSYSlinearly moves to the final values at its own (shorter or equal) stepsize.


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Issues solved Staticapproach

OLGAStandalone

OLGA/HYSYSLinked

Prediction of slu henomena - ++ ++

Overpressure protection of process inlet

Integrated approach; forced coupling ofmultiphase and process diciplines

- + ++

Account for volume accumulation - ++ +++

Dynamic response from other flowlines - ++ ++

Prediction of separator performance - + +++


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ynam c response rom are sys em an o erdownstream systems - + +++

User friendliness with regard to interpretation ofprocess results

+ + +++

Benefits gained by us ing HYSYS as the topside processsimulator

Load reducing measures as piping/equipment volumes from other feedstreams, surrounding systems/segments can be included.

BPT has run cases where the full main topside process has been included, andwhere the design loads have been reduced significantly

Separators

Recompressors

Gas treatment

Gas compressor

Added volumes


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Added PSVcapacity

Added realism...


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Prediction of separator performance:Realistic geometries can be implemented

Flexibility wrt liquid carry-over functions

PSV modeling:Key factor is tuning of flow capacity

Stand alone HEM calculations required?(acc to API Std 521)


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Fast to get started, a model may already exist? User friendliness with regard to interpretation of process results


Simulation of Primary & Instrumented Secondary Protection systems.Rigorous models of all relevant equipment, including Unit Op. for Cause & Effects.


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Example

Case: Separator conditions following fail opening at time=1050s Value

Gas/Oil fluid with GOR 1500 Max GAS flow peak into separator at timeMax OIL flow peak into separator at time

Max TOTAL mass flow (used in static calculations)

+5 s+19 s

135 kg/s

u e e a meMax TOTAL relief

No relief duringinitial peak flow

+ s70 kg/s

Reduction indesign relief flow

(static vs dynamic)30-50%


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Example

Tie-in of high GOR (3000)satelitte field to an existing NorthSea operating facility.

Objective to verify that facility has

Flowline initial condition: maximumshut-in

Fail opening towards separatorwith closed outlets (that is, firstproducer towards this separator)

Normalized data:


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Level/Vessel ID Flowrates/typical


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Example

1


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Graph for PRIMARY barrrierdefines the requirementfor thePSD functionto close inlet valves

1

Example flare rate reduction


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Example

Choke collapse incidents:Any sudden increase in valve capacity.

Flexibility wrt modeling of collapsing valve: Capacity is dependant of initial opening

at start of incident:

(1) Valve closed, about to open (high dP)=> collapsed capacity < design capacity?

(2) Valve fully open=> capacity >> design capacity

(2)


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(1)

Economic benefits

Although the main result from such overpressure protection studies are relatedto plant safety, huge cost impacts may be gained:

A too high flowline arrival PSD PSHH setting and/or a too large choke size may result in anunprotected system :=> None-API secondar rotection=> Potential loss of installation => Cost/HSE impact?

Need of flare system modification ? (if yes, a full topside production shutdown is required for xnumber of days/weeks) => Cost/HSE impact?

Optimization of production choke capacity.If over-conservative assumptions must be taken dueto a non-rigorous calculation, the production choke willunnecessary limit the production for x number of years)=> Cost/HSE impact ?

Plant operability and regularity vs

plant Integrity Extend operational limits(raise flowline PSHH)?

Remove interlocks?

Simplify procedures?


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ee or more compex n e arrangemen con gura on;2 x 50% or 3 x 33% lines with block valves and productionchokes to reduce relief rates? => Cost/HSE impact

A too conservative (low) PSD PSHH setting causesunnecessary trips. => Reduced availability => Cost impact?

e uce ma ntenance requ rements


Allow for choke col lapse indesign?


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Conclusions

By using dynamic simulations in the design of overpressure protectionsystems, a better utilization of existing as well as newinstallations can be achieved

a erdesign without restricting ro uc on or an pera y. Integrated multiphase and process dynamic simulations (OLGA /HYSYS)

provides improved capabilities

Direct transfer of dynamic responses frompipeline to process model

Simultaneous simulation of pipeline androcess d namics

- More realisticdesign cases- Improvedunder-standingis ained


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Dynamic picture of overpressure from wellheadto flare tip is achieved

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