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Elgin: key facts & figures
2
On stream since 2001
6 producing wells from 4 HP/HT fields
Produced 135k boe/d in 2011
Operated by Total for 8 x JV partners
Production Utilities Quarters (PUQ) & wellhead platforms linked by 90m bridge
Elgin G4: well architecture
3
Well head deck on Elgin ‘A’ platform
Seabed @ 93m below platform
Chalk HOD non-producing
low permeability high pressure
Fulmar producing
high permeability lower pressure
25 Feb: sudden decrease of A annulus pressure and rapid increase in B and then C annulus
G4 Task Force established: well intervention prepared with Rowan Viking rig support
15 March: tubing and A annulus contents displaced to 1.2sg brine
22 - 25 March: well killing
start pumping 2.05sg OBM down tubing & up A annulus B & C annuli pressure increase
C annulus bled off through WHP process B annulus operating window increased
after 172m3 operation suspended as mud returns to the process via C annulus
attempt to re-route C annulus returns line to surge tank
sudden unsustainable C & B annuli pressure increase - leading to gas release at well head D annulus
Elgin G4 leak: build-up
4
Specialised team mobilised to complete thorough incident investigation
Elgin G4 leak: day one (25 March)
5
12.20: gas & condensate leak confirmed at the wellhead on Elgin’s G4 well
13.30: evacuation begins of Elgin and the adjacent Rowan Viking drilling rig
16.40: 219 people have now been evacuated – leaving 19 still on the complex
01.45: Elgin OIM decides to fully abandon
Platform, rig & wells shut down - but flare still lit
Export pipelines isolated
02.30: the last 19 people are evacuated
All 238 people safely and quickly evacuated
Elgin G4 leak: initial impacts
Gas, condensate & mud released via D annulus
Visible gas plume formed
Condensate & mud falls to sea
Sheen covers a large area of sea surface
Waxy paraffinic deposits on wellhead platform
6
Elgin G4 leak: initial response
Informed all appropriate Authorities
Mobilised Emergency & Crisis Response Teams
Oil Pollution Emergency Plan (OPEP) activated
Enforced sea & air exclusion zones (2 & 3 N miles)
Mobilised a fleet of safety & support vessels
Dispersant ships and planes put on standby
Recruited Wild Well Control to assist
Mobilised Oil Spill Response Limited (OSRL)
7
The Skandi Aker well intervention vessel
The Ocean Ness Emergency Response & Rescue Vessel
Elgin G4 leak: options to regain well control
Preferred Option: a pumped well kill operation a mobile pumping unit putting heavy mud directly into G4 from the wellhead
technically feasible
re-boarding of the Elgin wellhead platform necessary
Wild Well Control already mobilised and suitably experienced
no absolute guarantee of success
timescale measured in weeks
Back-up Option: drill a relief well a contingency in the event the well kill is ineffective
technically feasible
start drillng two wells and use the one that reaches the interception point first
two drilling rigs (Rowan Gorrilla V & Sedco 714) already on Total’s books
success virtually assured
timescale measured in months
8
Elgin G4 leak: post incident milestones (1)
29 March: OSRL flights reveal size of sheen has already diminished considerably
30 March: flare is confirmed as extinguished
2 April: well kill & relief well options announced
5 April: first re-boarding of Elgin complex by Wild Well Control & Total E&P UK teams
15 April: mobilisation of West Phoenix drilling rig & Skandi Aker as main well kill support vessels
18 April: Sedco 714 spuds first relief well
26 April: special ‘diverter’ fitted to G4 well head
10
The Sedco 714 drilling rig
The diverter on the G4 wellhead Fitting the diverter was ‘a game changer’
Elgin G4 leak: post incident milestones (2)
Successful removal of waxy deposits
Laying of 230m of ‘chiksan’ pipeline
10 May: West Phoenix drilling rig alongside
10/15 May: extensive equipment testing
15 May: Well kill operation begins
11
Daily cleaning operations on the Elgin well head platform
The West Phoenix; the main well kill support vessel
‘Chiksan’ temporary rigid pipeline
Elgin G4 leak: well kill operation
Dynamic well kill with 2.05sg mud
Initially pumped water based mud (WBM)
Pumped through G4 wellhead into tubing
1000m3 pumped @ a rate of 8-12bbls/min
Pumped via Coflex & chiksan from West Phoenix
Pumping for 12 hours
No diversion: pumped fluids exited to sea
After 5 days, WBM replaced with oil based mud
14
G4 now stable and under observation
Elgin G4 leak: current status
15
The well has been ‘killed’ and is filled with oil based mud
The well & gas leak path are under control
Progressive re-manning of the Elgin complex & the Rowan Viking is underway
The West Phoenix will be demobilised once the Rowan Viking’s pumps are available
As a contingency, drilling of relief well 1 to continue for now
But a decision taken not to drill relief well 2
Other Elgin/Franklin wells being monitored
16
Elgin G4 leak: environmental impacts
Widespread consensus that the environmental impacts are minimal
Environment Monitoring Activities
2 Oil Spill Response Limited (OSRL) flights per day to monitor marine pollution
Regular survey flights by the National Centre for Atmospheric Science (NCAS)
Daily water samples taken in Elgin surroundings
Leak flow rate estimated at an initial 2kg/s but quickly fell to less than 0.6kg/s
Gas composition: 70% methane + 30% ethane, butane, etc; no H2S traces
Surface sheen extended many kms, but was less than 1/10th of a micron thick
Light condensate that disperses naturally and easily: 50% evaporation in the first 24 hours alone
Several independent chemical, sediment and & fish analyses confirmed no direct marine contamination (eg, Scottish Government, etc)
Elgin G4 leak: next steps
17
Fully re-man the Elgin complex, including on-board sleeping, etc
Re-man the Rowan Viking drilling rig and get its pumps working
Continue to deep clean the Elgin complex, power up & test on board systems
Demobilise the West Phoenix (when Rowan Viking’s pumps are working)
Set a 50m cement plug in well G4 as part of abandonment process
Stop drilling relief well (when cement plug in place)
Co-operate fully with on going HSE investigation
Work towards gradual resumption of normal operations
Adopt lessons learned and share with the wider industry