draugen well integrity improvement project · campaign conclusions (1) successful temporary repair...
TRANSCRIPT
Copyright of Norske Shell 16/25/2013
DRAUGEN WELL INTEGRITY
IMPROVEMENT PROJECT
WIF Well Integrity Workshop
Residence Hotel, Sandnes
4th June 2013
Ksenia Arkhipova and Jan Sæby
Production Technologists
AS Norske Shell
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AGENDA
Draugen History and Field
Overview
Lifetime Extension Challenges
Well Integrity Issues with Ageing
Well Stock
Review of Platform X-mas Tree
Change Out and WI Improvement
Campaign
Conclusions
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D3H
E3H
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DRAUGEN FIELD OVERVIEW
A/S Norske Shell (44.56%)
Chevron Norge AS (7.56%)
Petoro AS (47.88%)
PL 255 in Block 6407/9Discovered 1984 w/development start 1993Haltenbanken basin, 250 m water depth, 1640 mssLow relief N-S trending anticlinal structure, 20 x 6 kmVery good reservoir properties, 28-32% por, 5+ Darcy
Fluid: Light undersaturated oil Artificial lift: gas liftDrive mechanism: weak aquifer drivePressure support: water flood (sea water, PWRI from 2013 onwards)Expected RF 73%
Wells:14 producers, 6 platform, 8 subsea5 water injectors on 2 templates (SWIT, NWIT)1 gas injector – suspended4 infill wells planned, 3 P&A’s planned
Current Production 5800 Sm3/dAverage water cut: 83%
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PRODUCTION HISTORY & KEY EVENTS
FIRST OIL ON DRAUGEN
October 19th 1993
October 1994 – Water injection in the north and south came on line with 5 injectors
July 2000 – Highest production reached with 39,978 sm3/day
End 2000 – 8 Producing wells on Draugen
Year 2002 – Subsea development of Garn West and Rogn South
Mid 2002 – Plateau production period is over, significant
increase in water break through
Mid 2005 – Water injection in NWIT is suspended due to ruptured flowline.
Rupture is fixed however NWIT remains suspended.
Year 2008 – Two new wells are drilled (D3 and E3).
December 2011 – FID on Draugen Infill 4 new wells to
be drilled.
Draugen Production Forecast
Changing Operating Conditions:
Tail end oil production, < 5000 m3/d
Significant water production, 25-45,000 m3/d
Increasing H2S levels
Seawater injection replaced by PWRI
Ageing Facilities
Lifetime Extension Challenges
Initial field life expectation – 20 years, i.e. 1993 to +/- 2013.
Current license end – 2024, Production expected to last until 2035
Ageing Wells and Facilities
Challenge to maintain well and asset integrity
Obsolete Ingram Cactus 5k X-mas trees
No ASV installed
Increasing number of Well Integrity failures and long lead times for repair
No drilling/workover capability on platform
End of field life P&A strategy for platform wells, continued monitoring required for
watered out wells
Opex Containment
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KEY WELL INTEGRITY ISSUES
Platform wells:
Corroded valve seats in platform X-mas trees
Leaking wellhead seals due to introduction of gas lift => pressure in cavities, A to B ann. communication
DHSV and control line problems
Damaged spindle on B- and C-annulus valves on patform wells
Unknown tubing corrosion status
Subsea wells:
Tree valve operabilities
Hydrates in leaking XOV’s
Well Integrity Testing requirements:
WIT 6 monthly
SIT every 2 years
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WELL INTEGRITY ISSUE 1 – PLATFORM WELL A6
Conclusion: Breach of secondary barrier (tubing hanger). Well not in compliance with Norsok D-010 nor Shell Well Integrity Policy.
Draugen A6 – gas lifted platform well
Gas Lift introduced in 2002
Well closed in February 2008 due to external leak through test plug on XT
Investigation concludes with a gas leak through tubing hanger packoff (JS-seal) caused by the A-annulus lift gas (high pressure)
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LEAK PATH IN TUBING HANGER
JS-seal cav.
TP5
VoidTP2
Check valve
Test port plug
Bleed port plug
JS-seal assembly
JS-seal assembly
Neck sealTubing
Annulus A
Contained system
External environment
Bleed line Test
line
Leak path: Injection gas passing the JS seals, then entering the void and displacing the void fluid, which in turn leaked through a failed check valve and the improperly torqued plug.
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TEMPORARY MITIGATING MEASURES
Classify the tubing hanger as a weakened well
barrier (leak rate less than ALR (0.5%))
Replaced and qualified the plugs and check valves
on test- and bleed ports as additional barriers for
containing void pressure
Established compensating surveillance measures Daily visual inspection
Plug movement
Seeping fluid
Foam leak test on plugs Monthly, 3 monthly, 6 monthly
Get approval from TA’s, notified PSA (Ptil) Continue production under deviation (with 6-
monthly Technical Reviews and Risk Assessments)
while reviewing more permanent repair options
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A6 EXT. LEAK REPAIR ACTIONS
External leak fixed and pressure from void contained by pressure tested test- and bleed
plugs
Plugs gas rated to 5.000 psi and Pressure tested
Tubing Hanger Neck seal tested OK.
Repair tubing hanger packoff (JS-seal) by injecting chemical sealant (GlyFlo by Seal-Tite). Finally test and qualify/disqualify the tubing hanger packoff performance.
Seal repair job was not successful
Tubing hanger voids still charged with pressure
Later the leak developed into A to B- communication, again loss of secondary barrier
Continue investigate for a long-term solution Workover?
Chemical sealant?
Alternative design?
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WELL INTEGRITY ISSUE 2 – PLATFORM WELL A1
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Draugen A1 – gas lifted platform well
2010 events:
HP hydraulic oil leak from failed WRSSSV
During change out, identified UMV leaking (failed WIT test)
Replaced UMV seals – leak worsened; observed ‘pitting’ on sealing faces of
valve seat
Planned temporary fix by online milling of X-mas tree UMV seat
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MILLING OPERATIONS PLANNING
13
NCA – Norse Cutting & Abandonment
Equipment: Lineboring Machine (60 rpm), Zone II ratedHyd Power Unit (15 kW)
• Initial onshore tests
required LMV opened, this
was rejected in HAZID
and required further trials
with closed LMV!
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MILLING OPERATIONS
14
• Successful operation
• no accidents or incidents
• 3mm milled
• over-sized seal installed
• restored integrity to UMV in 5
days (including Wireline plug
recovery)
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EXPERIENCE FROM NCS
Statoil and other operators have considerable experience with similar problems
Leaking JS-seals
Leaking neck-seals
Leaking ring and radial gaskets
Occurs typically within 2-3 years after the wells have been put on gaslift
Old and often Obsolete designs
Seals not optimized, designed and properly tested for long term gas integrity
Test procedures and criterias
Seal design
Material selection (elastomer/rubber)
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DRAUGEN WELL INTEGRITY IMPROVEMENT PROJECT
• The lifetime on Draugen was extended with +/- 20 years, there were
increasing H2S levels and WI issues => improved WI was required
• Based on A1 findings (damaged tree valve seats), it was advisable to
changeout 4 out of 6 platform wells Xmas trees with upgraded specs
(Inconel valve seats) over the forthcoming years – wells had been in
production for 20 years.
• The X-mas change outs would also allow to address the JS seal
problems and the other WI issues (leaking annulus valves, control line
leaks)
• Xmas trees purchased from Cameron (40 week lead time)
• Identical interfaces to existing trees (like for like replacement) but upgraded seats
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A1, A6 AND A3 X-MAS TREE CHANGE OUT OPERATIONS
Tree preparation for retrieval,
removed speed lock clamp in
preparation for tree lift
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Old tree lifted out of location
Unable to remove old Xmas
tree with pull of 6500 kg by an
overhead crane. Had to utilise
the lifting jacks (550 Kgs) to
‘break the seal’ or used
pressure in the tubing hanger
cavity to assist breaking
The new Xmas trees were landed and secured in correct orientation first time!
Challenges with removing the Tubing Hanger
Flange Seal
Constructed a fit-for-purpose tool used to remove
flange (only ¼ turn was tight, then by hand)Wellhead, old gasket, metal-to-metal seals – all was found in the good condition
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SUMMARY OF DRAUGEN WI IMPROVEMENTCAMPAIGN
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Well no. WI issue Mitigation/Temporary repair Permanent Repair CommentsA1 Pitting corrosion in UMGV, failed leak test Onsite milling New X-mas tree installed
A to B annulus communication Treatment w/Brinker Plasma Re-application of Brinker every 2 yearsLeaking WRSSSV, high hydraulic fluid usage Produced under deviation Replaced WRSSSV WRSSSV held up in X-mas tree during change outLeaking C-annulus valve Replaced valveNon Qualified GLV as barrier element Installed PTC GLVPossible Tubing Corrosion Ran caliper survey Survey indicated tubing in good condition
A2 Leaking Swab valve, not passing WIT test Change out valve seals X-mas tree change outRemaining well w/obsolete X-mas tree Produce under deviation X-mas tree change out X-mas tree repalcement planned Q4 2013
Accidental leak to environment in Apr'13A3 Leaking Tubing hanger seals Treatment w/Brinker Plasma Re-application of Brinker every 2 years
Leaking JS seals, A to B annulus comm. Treatment w/Brinker Plasma Re-application of Brinker every 2 yearsDamaged spindle in B-ann. valve Produced under deviation Replaced valve
A6 Leaking tree cavity test plug Frequent inspection routines Changed out Test Plugs Leak to environment in 2008Leaking JS-seals, A to B annulus comm. Treatment w/Brinker Plasma Re-application of Brinker every 2 yearsDamaged spindle in C-ann. Valve Produced under deviation Replaced valveLeak into DHSV control line Possibly install WRSSSV
Campaign Conclusions (1)
Successful Temporary repair by onsite milling of UMGV seat (3 mm) allowed continued
production until new trees were available
Successful Change out of X-mas trees on A1 (May 2012), A6 (Feb 2013) and A3 (Mar
2013), campaign for each well taking 30 to 40 days.
Successful Change out of C-annulus (A1, A6) and B-annulus (A3) Side Outlet Valves.
Successful repair of JS seals with Brinker Plasma (additional treatments every 2 years),
all wellhead voids treated
Change out of GLV’s as part of primary barrier, old in relatively good condition
Completed multi-finger caliper survey in A1 – tubing in good condition with no significant
penetrations, areas of cross-sectional wall loss or ID restrictions
Change out of failed DHSV in A1
3 Well Integrity issues resoved with each X-mas tree change out, no need for deviations!
Campaign Conclusions (2)
Significant learnings in campaign operation
Problems with change out of Engineering
contractor between jobs
Interfaces between departments (Ops-Eng-
CWI-DE) are a real challenge
A2 X-mas tree change out still outstanding,
planned for Q4 2013
Upon Completion of the WI improvement
campaign, the Draugen platform wells will
have renewed WI to face continued
production for next 20 years.
Thank You !
Any Questions?