A/S Norske Shell

DRAUGEN PLATFORM WELLSWELL INTEGRITY CHALLENGES WITH AGEING ASSETSWELL AND CHRISTMAS TREE CORROSION HISTORY

Presentation at WIF Seminar 13th June 2019

Jan Sæby

1

PT DL & Well Integrity TA2

A/S Norske Shell

Agenda

➢ Draugen Field background and history

➢ Historical Well integrity issues and Lifetime Extension

➢ First X-mas tree change outs

➢ Well Integrity degradation and 2018 WI campaign

➢ Second X-mas tree change outs

➢ Final Conclusions

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Draugen

3

◼ 6 platform producers, 5 operational

◼ 11 subsea producers

◼ 5 water injectors (4 operational) on 2 templates

◼ 3 abandoned subsea wells

Draugen 6407/9, PL093, Developed by Shell, now operated by OKEA

Water depth 251 m

Reservoir Type shallow marine, upper shore face sandstone reservoir

Structure low relief N-S trending anticlinal structure

Areal extend 20 x 6 km

Max Vertical closure 50 m

FWL 1640 TVDSS

Reservoir Upper Jurassic Rogn/Garn

Porosity 28-32 %

Permeability 5+ Darcy

Initial Reservoir Pressure 165 bara, hydrostatic

Reservoir Fluid light under-saturated oil, with no associated gas cap

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Draugen Historical Production and 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, Integrity problems

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Completion A-1, A-2, A-3, A-6

Standard completion:◼ Ingram Cactus 5k X-mas trees (obsolete design)

◼ 7” x 5.5” tubing

◼ 10 ¾ x 9 ⅝” production casing

◼ 13 ⅜” intermediate casing

◼ 18 ⅝” surface casing – load bearing

◼ 26” conductor

◼ Open hole with 6 ⅝” slimpack screens, 300

◼ 1 GLV: PTC high reliability valve

◼ Below SSSV, part of primary barrier

◼ A4 installed with 9 ⅝” tubing and a CT insert for

gas lift

5June 2014

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Lifetime Extension Challenges

◼ Initial field life expectation – 20 years, i.e. 1993 to +/- 2013. ➢ Lifetime extended to 2032 in 2013

Ageing Wells and Facilities➢ Challenges to maintain well and asset integrity➢ Obsolete Ingram Cactus 5k X-mas trees➢ Gaslifted wells with no ASV installed

Increasing number of Well Integrity failures and long lead times for repairNo drilling/workover capability on platformEnd of field life P&A strategy for platform wells, continued monitoring required for watered out wellsOpex Containment

OKEA took over operatorship on 01.12.2018.

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Key platform Well Integrity issues

Number and severity of WI issues has been increasing with ageing of the Draugen asset. ➢A5 collapse due to corroded surface casing in splash zone (2003)➢ A6 external liftgas leak through corroded test plug from tubing hanger cavity (2008) ➢ Leaking wellhead seals due to introduction of gas lift => pressure in cavities, A to B ann. communication. Controlled with Brinker treatments.➢ DHSV and control line problems, A1 insert DHSV➢ A1 corroded master valve seat, milling repair (2012)➢ Damaged spindle on B- and C-annulus valves on patform wells➢ Surface Casing corrosion discovered in top splash zone (2013), A4 and A6 repaired with clamps➢ 4 new X-mas trees (w/inconel seats) installed in 2012-2014 as part of LTE project➢ Leaking tree valves (PMV, PWV, GLIS etc..) on new trees (2016-2018)➢ Well Integrity repair campaign (2018) discovered significant corrosion in the new X-mas trees due to souring conditions➢ 2nd X-mas tree repair and WI improvement campaign (2018-2019)

Corroded Surface Casings

Leaking Tree valves, PMV, PWV

Corroded Valve seat and housings

Gas leak, wellhead test plug,

A-B communication

Leaaking B and C-ann. valves

Leaking GLIS valves

Control Line Leaks

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Gas leak on platform well A6

Conclusion: Breach of secondary barrier in well (tubing hanger)/primary barrier to gaslift.

▪ Gas Lift introduced in 2002

▪ Well closed in February 2008 due to

external leak through test plug on XT

▪ Investigation concluded with a injection

gas at high pressure leaking through

tubing hanger packoff (JS-seal) to tubing

hanger void, that leaked through a failed

check valve and improperly torqued plug.

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A1 PMV milling repair operation (2012)

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• Successful operation• no accidents or incidents

• 3mm milled

• over-sized seal installed

• restored integrity to PMV in 5 days

(including Wireline plug recovery)

◼ PMV failed WIT test

◼ Observed pitting of sealing faces of valve seat

◼ Temporary fix by online milling with Lineboring

Machine of valve seat by NCA, Norse Cutting &

Abandonment

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A1, A6, A3 and A2 X-mas Tree Change out operations (2012-2014)

Tree preparation for retrieval,

removed speed lock clamp in

preparation for tree lift

106/12/2019

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!

Campaign took 30-40 days per tree change out.

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

▪ New X-mas trees with improved Inconel seal faces

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A4 Surface Casing Corrosion Repair (2016)

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➢ PEC surveys identified up to 65% wall thickness loss.

➢ Camera run (boroscope) had identified a casing

leak

➢ Conductor was removed, severe corrosion and large

holes in surface casing discovered in induced splash

zone

➢ Three step repair solution:

◼ Install temporary support system

◼ Composite wrap (Belzona Supermetal and

Superwrap) to fill surface defects, repair holes and

restore pressure integrity

◼ Clamping and jacking arrangment including Shims to

relieve weight and restore structural capacity

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Draugen eWIMS Status March 2018

◼ Total 23 wells, 12 wells with WI issues, 8 wells deviated, 34% vs target 2% deviations.

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Draugen WI Campaign 2018

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◼ The progress was slower than expected due to the findings and extended scope so A6 was moved to Phase 2

◼ Inspection of A5 was also included in Phase 2 to check if it could be used as replacement tree for A1

Draugen Integrity Scope Campaign - 1 28. Feb – 21. March

A1 New tree installed in March 2012Repair UMVReplace FWVRepair GlisReplace B-annulus valveA4 Tree from 1999, Master and Wingvalve from 2005Repair Wing valveReplace Glis Replace Grease nipple A-annulusReplace Grease nipple B-annulusReplace Blind-plugsSealant treatment of 9 5/8'' and 13 3/8” tbg/csg hanger void. A6 New tree installed in February 2013Repair FWVReplace Greasenipple C-annulus

Draugen Integrity Scope Campaign -2 10. May – 20. June

A-3 New tree installed in March 2013

Replace Grease nipple C-annulus

Replace Blind-plugs

Seal-Tite treatment of 10 ¾” casing hanger void

A-2 New tree installed in February 2014

Repair UMV

Repair FWV

Replace Grease nipple B-annulus

Replace Grease nipple C-annulus

Replace Blind-plugs

Seal Tite treatment 10 ¾” and18 5/8” csg hanger void

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Swab valveProduction wingvalve

Corrosion behind thisarea towards bolt holes

Upper Master valve

Lower master valve

A1 Xmas tree

A/S Norske Shell 12.06.2019 15

A1 – Upper Master Gate Valve

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Well A1 – Upper Master Gate Valve

september 2017 16

➢ Severe corrosion (9mm) found at the lower side of the bore inlet, behind the

Inconel seal face (in valve housing)

➢ Corrosion most likely due to corrosive fluids (water, H2S, CO2...) and material

incompatibility

➢ It was considered unsafe to continue production and the well was c/in awaiting

new tree change out

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Platform Well X-mas tree corrosion findings

◼ A6 FWV housing and bonnet, 2-3mm corroded

◼ A4 FWV seat, 4-5mm corroded

◼ A5 FWV, major

corrosion in seat area◼ A2 UMV, 5-6mm

corrosion in housing

◼ A3 UMV, 6mm corrosion in housing

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Main Findings and actions from X-mas tree WI campaign

➢ All Draugen platform well X-mas trees had severe, but variable, internal corrosion and need replacement with higher spec fully Inconel clad trees (HH spec). Replacement project started in Oct’18 and is now being continued/completed by the new operator OKEA

➢ The valve housings of the 4 new “improved” trees installed in 2012-14 had corroded very fast (1-2 mm/yr) due to incompatibility with todays produced fluids (increased corrosion also seen in oil trains).

➢ Corrosion mechanism is thought to be due to Sour corrosion due to CO2 and increasing H2S levels caused by reservoir souring. The corrosion is worsened by galvanic effects at the interfaces with the Inconel inlays.

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Final Remarks

▪ Draugen has had significant WI and corrosion issues over its life so far

▪ LTE’s of ageing fields is causing Well and Asset Integrity challenges that have to be properly addressed and mitigated

▪ Produced fluids compositions are changing and there may be material incompatibility.

➢ With new improved X-mas trees, the Draugen platform wells are expected to be able to produce for another +/- 20 years.

➢ Well Integrity challenges will still be encountered and require continuous focus and attention to ensure safe production for the remaining lifetime of the field (e.g. Surface Casing corrosion and A-B communication).

Thank You !Any Questions?