1. University of York, UK Measurement of the Total Elgin gas leak, and future positive outcomes Stéphane Bauguitte Stephen Mobbs

2. University of York, UK Quantification and source identification of the Total Elgin gas leak, UK - North Sea, by aircraft sampling Stéphane Bauguitte 1, James Lee 2, Axel Wellpott 1, David Lowry 3, Rebecca Fisher 3, Alastair Lewis 2, James Hopkins 2, Grant Allen 4, Sebastian O'Shea 4, Mathias Lanoiselle 3, James France 3, Richard Lidster 2, Shalini Punjabi 2, Alistair J. Manning 5, Thomas B. Ryerson 6, Stephen Mobbs 7, Martin Gallagher 4, Hugh Coe 4, John A. Pyle 8, Euan Nisbet 3 1. Facility for Airborne Atmospheric Measurements (FAAM), Building 125, Cranfield University, Cranfield, UK 2. UK National Centre for Atmospheric Science, University of York, York, UK 3. Department of Earth Sciences, Royal Holloway, University of London, Egham, UK 4. School of Earth, Atmospheric and Environmental Sciences, Univiversity of Manchester, Manchester, UK 5. Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA 6. UK Meteorological Office, FitzRoy Road, Exeter, UK 7. UK National Centre for Atmospheric Science, University of Leeds, Leeds, UK 8. Centre for Atmospheric Science, Chemistry Department, Cambridge University, Cambridge, UK Oral presentation on Tues 4 Dec at AGU Fall Meeting, A21J, Atmospheric Impacts of Oil and Gas Development

3. University of York, UK Elgin incident overview Refer to Total Elgin website: www.elgin-total.com/elgin Elgin PUQ National Gas Transmission System 2010 Source: International Energy Agency & DECC

4. University of York, UK Elgin incident overview - timeline Platform evacuated 25 th March 2012 Initially it was not clear where the leak was - some reports said it was on the sea bed What is the leak rate? What is the source? Where is it emitting? 5 x sampling flights 30 th March – 4 th May

5. University of York, UK Measurements In situ CH 4, CO 2 (LGR FGGA) See poster (O’Shea et al, 2012) CO, O 3, NO x Grab samples whole air sample (WAS) system with 64 x 3 litre silco-steel canisters GC-FID: C 2 -C 8 NMHC and DMS; acetone GCxGC: C 6 -C 13 NMHC, oxygenated VOCs continuous flow GC-IRMS - Trace Gas and Isoprime mass spectrometer: Methane  13 C

6. University of York, UK Flight planning UK Met Office NAME dispersion model used to predict the path of the plume Also CH 4 levels for safety (40 ppm)

7. University of York, UK Elgin Platform Ahead of the FAAM Aircraft

8. University of York, UK CH 4 leak rate Plume intercepted at different distances from source and altitudes WAS taken in the centre of and outside the plume Profiles taken to assess mixing layer height

9. University of York, UK CH 4 leak rate – 30 th March CH 4 enhancements 5NM from platform

10. University of York, UK 15NM from platform – black is 30 th March, green is 3 rd April Calculate CH 4 leak using atmospheric mass flux calculation = constant uniform wind speed  = angle between aircraft track and direction normal to the wind direction n = atmospheric number density X m = mixing ratio enhancement White et al. 1976, Ryerson et al. 2011 CH 4 leak rate calculation

11. University of York, UK Source characterization  13 C measurements made from WAS samples Keeling plot (Pataki et al., 2003) gives information about the 13 C content of the plume  field identification

12. University of York, UK Source characterization (2)  13 C Elgin Ethane is ~-29‰ (Isaksen, 2004). Methane is likely to be similar The gas in the shallower (cooler) Hod is likely to be lighter: ~-43% is plausible Isaksen, GH (2004) Central North Sea hydrocarbon systems: Generation, migration, entrapment, and thermal degradation of oil and gas. AAPG Bull. 88, 1545-1572.

13. University of York, UK Summary Small Hod reservoir possibly linked to rapid leak rate depletion  C 13 measurements help confirm this Further 3 missions were flown until end of May Showed similar flux to 3 rd April flight (Stephen Mobbs’ re- analysis) DateCalculated CH 4 flux (kg s -1 ) by direct integration (White et al. 1976, Ryerson et al. 2011)  13 C CH4 (‰) ±2  error (Pataki et al., 2003) 30 March 20121.3 ± 0.4-43.0 ± 0.5 03 April 20120.4 ± 0.3-41.9 ± 1.0 Both Flights-42.3 ± 0.7

14. University of York, UK Non-Methane HydroCarbons (NMHC) Presence of light alkanes confirms that the release was not from a great depth Contrast with BP Deep Water Horizon incident investigated by NOAA Photo released by Total on 5 th April

15. University of York, UK 2 nd Dimension / s 1 4 5 0 1 st Dimension / min 08.3316.6733.3341.6750 Aromatics Alkanes 2 nd Dimension / s 1 4 5 0 1 st Dimension / min 08.3316.6733.3341.6750 Increased Polarity Increased B.P Background Plume sample C6C6 C5C5 C7C7 C5C5 Benzene Toluene Ethyl Benzene / xylenes C 3 mono-sub aromatics C 4 mono-sub aromatics C8C8 C9C9 C 10 C 11 C 12 C 13 NMHCs (2) 2 nd Dimension / s 1 4 5 0 1 st Dimension / min 08.3316.6733.3341.6750 C6C6 C7C7 C5C5 Benzene Toluene Ethyl Benzene / xylenes C 3 mono-sub aromatics C 4 mono-sub aromatics C8C8 C9C9 C 10 C 11 C 12 C 13 Oxygenates Central London air shows more oxygenated compounds, less prevalent aliphatic band Total ~3.5 ppbv aromatics, ~2 ppb aliphatics Background air upwind of the plume, low VOC levels Sum of other HC (C 8 – C 14 ) in plume ~ 4 ppbv (~2% of HC atmospheric composition) Oxygenates

16. University of York, UK Financial implications From the flux calculation it was judged safe to board the platform Platform reoccupied 16 th May Well was killed after 3 months Total cost to UK fiscus £1bn Plan B was a bottom-kill by drilling a relief well: 6 months and likely cost to fiscus £3bn

17. University of York, UK Acknowledgements Pilots and operations staff at DirectFlight Ltd FAAM ops Everyone else who helped with the flights Thank You

18. University of York, UK

19. 15NM from platform 30 th March 3 rd April

20. University of York, UK In-situ methane measurements Analyser procured commercially in 2009 from Los Gatos Research Inc. Fast Greenhouse Gas Analyser (FGGA) model RMT-200 Customisation for airborne operation includes: - external sampling pump (KNF Neuberger model N920APDCB) - provision of in-flight calibration for instrument sensitivity/stability checks, to allow post-processing of dry air mole fractions traceable to greenhouse gas scales of Global Atmospheric Watch programme, World Meteorological Organisation (WMO) Instrumental performance based on analysis of in-flight (known) target concentration measurements: 1 Hz accuracy 0.07 ± 2.48 ppbv for CH 4 and -0.06 ± 0.66 ppmv for CO 2 All observed plume CH 4 enhancements well within instrument detection limit and response instrumental response speed was adequate. Inlet lagtimes (few secs) not an issue O’Shea et al 2012 AMTD

21. University of York, UK In-situ methane measurements FAAM core chemistry instrumentation rack installed in mid-cabin WMO traceable calibration gas standard cylinders installed at rear of cabin Used for FGGA calibration FGGA Pump Calibration

22. University of York, UK Whole air samples Up to 64 silco-steel canisters fitted to the rear hold of the aircraft Each of 3 litre internal volume Filled using an all stainless steel assembly metal bellows pump and manifold. Samples are taken from the main sample inlet pipe on the aircraft Canisters removed from aircraft for analysis

23. University of York, UK Non Methane Hydrocarbon (NMHC) measurements (1) Samples dried using condensation tube held at –30 °C Preconcentrated (–20 °C) using a multi-bed adsorbent trap (Carboxen 1000 and Carbotrap B) Thermally desorbed (330 °C) and injected into GC oven Sample split between two GC columns (a 50 m, 0.53 μm i.d. PLOT column and a 10m, 0.53 μm LOWOX column) Flame Ionisation Detection (FID) C 2 -C 8 NMHC and DMS C 6 -C 8 NMHC, DMS, acetone, methanol and acetaldehyde Analysis and Separation

24. University of York, UK Non Methane Hydrocarbon (NMHC) measurements (2) Comprehensive GCxGC Modulator Detector Injector Two columns are connected via a modulator The Modulator fractionates the flow from the primary column and injects it onto the second at regular time intervals c.a 2-7s Gives significant increases in peak capacity!

25. University of York, UK GCxGC t t Modulator 1 2 3 4 5 6 7 7 6 5 4 3 2 1 1 st dimension RT Boiling point 2 nd dimension RT Polarity A BCD A.Co-eluting peak enters the modulator. B.The Modulator fractionates the flow. C.These are injected onto the second column at regular time intervals, second dimension separation is completed before the next plug is injected. D.This 1D data can the be shown as a 2D contour plot.

26. University of York, UK Methane  13C Analysis at Royal Holloway Methane  13C measured by continuous flow GC-IRMS using a Trace Gas and Isoprime mass spectrometer (Isoprime Ltd.) Precision (repeatability) to 0.05‰ for CH4  13C analysis. Small sample volume (75 mL for ambient air) and fast analysis time (16 minutes per analysis) allows high throughput of air samples. Instrument has been run since 2003 with no deterioration in efficiency of the palladium catalyst. Typically 150 analyses per week New Picarro instruments, Ascension Is and Falklands Fisher et al., Rapid Communications in Mass Spectrometry, 2006. RHUL  13 C CH4 data