Elgin G4 Leak. 25 March 16 May 2012

Transcription

1 Elgin G4 Leak 25 March 16 May 2012

2 Elgin: key facts & figures Operated by Total for 8 x JV partners Production Utilities Quarters (PUQ) & wellhead platforms linked by 90m bridge On stream since producing wells from 4 HP/HT fields Produced 135k boe/d in

3 Elgin G4: well architecture Well head deck on Elgin A platform 93m below platform Chalk HOD non-producing low permeability high pressure Fulmar producing high permeability lower pressure 3

4 Elgin G4 leak: build-up 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 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 172m 3 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 4 Specialised team mobilised to complete thorough incident investigation

5 Elgin G4 leak: day one (25 March) 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 5

6 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

7 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 The Skandi Aker well intervention vessel Dispersant ships and planes put on standby Recruited Wild Well Control to assist Mobilised Oil Spill Response Limited (OSRL) The Ocean Ness Emergency Response & Rescue Vessel 7

8 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

9 Elgin G4 leak: options to regain well control 9

10 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 The Sedco 714 drilling rig 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 Fitting the diverter was a game changer The diverter on the G4 wellhead 10

11 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 The West Phoenix; the main well kill support vessel Daily cleaning operations on the Elgin well head platform Chiksan temporary rigid pipeline 11

12 Elgin G4 leak: well kill set-up Pre-kill testing, using Coflex from West Phoenix to Elgin PUQ 12

13 Elgin G4 leak: well kill operation Nearing the end of the well kill operation 13

14 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 1000m 3 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 G4 now stable and under observation 14

15 Elgin G4 leak: current status 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 15

16 Elgin G4 leak: environmental impacts 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 1/10 th 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) Widespread consensus that the environmental impacts are minimal 16

17 Elgin G4 leak: next steps 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 17

18 Thank you for listening any questions?