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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?
Larger chokes/less change-outs?
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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Benefits gained by us ing HYSYS as the topside processsimulator
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
Benefits gained by us ing HYSYS as the topside processsimulator
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
Larger chokes/less change-outs?
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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