1790 PROPOSED BROWSE TO NWS PROJECT – DRAFT EIS/ERD Chapter 10 D.5 RPS Oil Spill Modelling Report BROWSE TO NWS PROJECT - QUANTITATIVE SPILL RISK ASSESSMENT Report MAW0815J Browse to NWS Project - Quantitative Spill Risk Assessment Rev 4 27 November 2019 ES udi T www.rpsgroup.com/mst S ical N CH E T 10D PROPOSED BROWSE TO NWS PROJECT – DRAFT EIS/ERD APPENDICES 1791 REPORT Document status Version Purpose of document Authored by Reviewed by Approved by Review date B. Gómez Rev A Internal review M. Watt D. Wright D. Wright 01/07/2019 J. Wynen-Gaugg B. Gómez Rev 0 Client review M. Watt D. Wright D. Wright 04/07/2019 J. Wynen-Gaugg B. Gómez Rev 1 Client review M. Watt R. Alexander D. Wright 25/07/2019 J. Wynen-Gaugg Rev 2 Client review J. Wynen-Gaugg R. Alexander D. Wright 29/08/2019 Rev 3 Client review J. Wynen-Gaugg R. Alexander D. Wright 05/11/2019 Rev 4 Client review N. Page D. Wright D. Wright 27/11/2019 Approval for issue David Wright 27 November 2019 This report was prepared by RPS within the terms of RPS’ engagement with its client and in direct response to a scope of services. This report is supplied for the sole and specific purpose for use by RPS’ client. The report does not account for any changes relating the subject matter of the report, or any legislative or regulatory changes that have occurred since the report was produced and that may affect the report. RPS does not accept any responsibility or liability for loss whatsoever to any third party caused by, related to or arising out of any use or reliance on the report. Prepared by: Prepared for: RPS Woodside Energy Ltd Level 2, 27-31 Troode Street Mia Yellagonga, 11 Mount Street West Perth WA 6005 Perth WA 6000 T +61 8 9211 1111 T +61 8 9348 4000 ES ES udi T S UDI MAW0815J | Browse to NWS Project - Quantitative Spill Risk Assessment | Rev 4 | 27 November 2019 T S www.rpsgroup.com/mst Page ii ical N CH ical E T N CH E 10DT 1792 PROPOSED BROWSE TO NWS PROJECT – DRAFT EIS/ERD REPORT Contents Executive Summary ........................................................................................................................................13 Metocean Influences ..............................................................................................................................13 Oil Characteristics ..................................................................................................................................13 Summary of Stochastic Assessment Results .........................................................................................14 Interpretation of Contour Figures .................................................................................................14 Scenario 1: Long-Term (77-Day) Surface/Subsea Blowout of Unstabilised Torosa Condensate at the TRA-C Well ....................................................................................................14 Scenario 2: Short-Term (24-Hour) Surface Release of Stabilised Torosa Condensate after a Vessel Cargo Tank Rupture at the Torosa FPSO Location ..............................................15 Scenario 3: Short-Term (Instantaneous) Surface Release of Stabilised Torosa Condensate after an FPSO Offtake System Failure at the Torosa FPSO Location ....................16 Scenario 4: Short-Term (Instantaneous) Surface Release of Marine Diesel after a Vessel Fuel Tank Rupture near the Rowley Shoals ................................................................................16 1 INTRODUCTION ...................................................................................................................................... 1 1.1 Background .................................................................................................................................... 1 1.2 Stochastic Modelling of Spill Scenarios ......................................................................................... 3 1.3 Deterministic Analysis .................................................................................................................... 4 1.4 Report Structure ............................................................................................................................. 4 2 MODELLING METHODOLOGY .............................................................................................................. 5 2.1 Description of the Models ............................................................................................................... 5 2.1.1 SIMAP ............................................................................................................................... 5 2.1.2 OILMAP ............................................................................................................................ 6 2.2 Calculation of Exposure Risks ....................................................................................................... 7 2.3 Inputs to the Risk Assessment ....................................................................................................... 8 2.3.1 Current Data ..................................................................................................................... 8 2.3.2 Wind Data .......................................................................................................................29 2.3.3 Water Temperature and Salinity Data ............................................................................32 2.3.4 Dispersion .......................................................................................................................32 2.3.5 Replication ......................................................................................................................32 2.3.6 Contact Thresholds .........................................................................................................34 2.3.7 Oil Characteristics ...........................................................................................................35 2.3.8 Weathering Characteristics .............................................................................................38 2.3.9 Emulsification Characteristics .........................................................................................49 2.3.10 Subsea Discharge Characteristics..................................................................................50 3 STOCHASTIC ASSESSMENT RESULTS ............................................................................................53 3.1 Overview ......................................................................................................................................53 3.2 Scenario 1: Long-Term (77-Day) Surface/Subsea Blowout of Unstabilised Torosa Condensate at the TRA-C Well ....................................................................................................56 3.2.1 Discussion of Results .....................................................................................................56 3.2.2 Results Tables and Figures ............................................................................................58 3.3 Scenario 2: Short-Term (24-Hour) Surface Release of Stabilised Torosa Condensate after a Vessel Cargo Tank Rupture at the Torosa FPSO Location ..............................................79 3.3.1 Discussion of Results .....................................................................................................79 3.3.2 Results Tables and Figures ............................................................................................81 3.4 Scenario 3: Short-Term (Instantaneous) Surface Release of Stabilised Torosa Condensate after an FPSO Offtake System Failure at the Torosa FPSO Location ..................102 3.4.1 Discussion of Results ...................................................................................................102 3.4.2 Results Tables and Figures ..........................................................................................104 3.5 Scenario 4: Short-Term (Instantaneous) Surface Release of Marine Diesel after a Vessel ES Fuel Tank Rupture near the Rowley Shoals ..............................................................................125 udi T S MAW0815J | Browse to NWS Project - Quantitative Spill Risk Assessment | Rev 4 | 27 November 2019 ical www.rpsgroup.com/mst Page iii N CH E T 10D PROPOSED BROWSE TO NWS PROJECT – DRAFT EIS/ERD APPENDICES 1793 REPORT 3.5.1 Discussion of Results ...................................................................................................125 3.5.2 Results Tables and Figures ..........................................................................................127 4 DETERMINISTIC ASSESSMENT RESULTS ......................................................................................148 4.1 Overview ....................................................................................................................................148 4.2 Scenario 1: Long-Term (77-Day) Surface/Subsea Blowout of Unstabilised Torosa Condensate at the TRA-C Well ..................................................................................................149 4.2.1 Simulation with Minimum Time to Oil Contact and Accumulation at Any Shoreline Receptor at Defined Thresholds ...................................................................................149 4.2.2 Simulation with Maximum Oil Accumulation across All Shoreline Receptors and at Any Individual Shoreline Receptor at Defined Threshold .........................................150