Gorgon Emp Gorgon Gas Development Drilling and Completion Program

7/26/2019 Gorgon Emp Gorgon Gas Development Drilling and Completion Program

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Chevron Australia Pty Ltd

Document No: G1-NT-PLNX0001023 Revision: 0

Revision Date: 9 June 2011 Copy No:

IP Security: Public

Environment PlanGorgon Gas Development Drilling andCompletion Program


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Document No: G1-NT-PLNX0001023 Environment Plan:

DMS ID: 00391225 Gorgon Gas Development Drilling and Completion Program

Revision Date: 9 June 2011 Revision: 0

Chevron Australia Pty Ltd Public Page v

Printed Date: 7 July 2011 Uncontrolled when Printed

Table of Contents

Terminology, Definitions and Abbreviations .................................................................................................. 9

Executive Summary ..................................................................................................................................... 18

1.0

Introduction ........................................................................................................................................ 19

1.1

Proponent ................................................................................................................................ 19

1.2

Project ..................................................................................................................................... 19

1.3

Location ................................................................................................................................... 19

1.4

Gorgon Gas Development Environmental Approvals ............................................................. 23

1.5

Purpose of this Plan ................................................................................................................ 24

1.5.1

Scope of this Environment Plan .............................................................................. 24

1.5.2

Requirements .......................................................................................................... 24

1.5.3

Hierarchy of Documentation .................................................................................... 26

1.5.4

Relevant Standards and Guidelines ........................................................................ 28

1.5.5

Stakeholder Consultation ........................................................................................ 29

1.5.6

Public Availability ..................................................................................................... 30

2.0

Drilling Activities ................................................................................................................................ 31

2.1

Overview ................................................................................................................................. 31

2.2

Well Design and Drilling Details .............................................................................................. 32

2.2.1

Design ...................................................................................................................... 32

2.2.2

Drilling Fluids and Chemical Additives .................................................................... 33

2.2.3

Drilling Fluids and Cuttings Handling and Disposal................................................. 34

2.2.4

Cleaning the SBM Holding Tanks ........................................................................... 35

2.2.5

Cementing Operations ............................................................................................. 35

2.2.6

Pre- and Post-drilling Seabed Surveys ................................................................... 35

2.2.7

Logging .................................................................................................................... 36

2.2.8

Well Testing and Clean-Up ...................................................................................... 36

2.2.9 Well Suspension and Completion ........................................................................... 36

2.2.10 Marine and Support Operations .............................................................................. 36

2.2.11

Time Frame ............................................................................................................. 37

3.0

Existing Marine Environment ............................................................................................................ 38

3.1

Physical Environment ............................................................................................................. 38

3.1.1

Bathymetry and Seabed Features ........................................................................... 38

3.1.2

Metocean Conditions ............................................................................................... 38

3.2

Marine Biological Environment ............................................................................................... 38

3.2.1 Benthic Flora and Fauna ......................................................................................... 39

3.2.2

Macrofauna .............................................................................................................. 39

3.3

Social and Economic Environment ......................................................................................... 43

3.3.1

Petroleum Activities ................................................................................................. 43

3.3.2

Fisheries .................................................................................................................. 43


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Environment Plan: Document No.: G1-NT-PLNX0001023

Gorgon Gas Development Drilling and Completion Program DMS ID: 00391225

Revision: 0 Revision Date: 9 June 2011

Page vi Public Chevron Australia Pty Ltd

Uncontrolled when Printed Printed Date: 7 July 2011

3.3.3

Shipping .................................................................................................................. 44

3.3.4

Recreational and Tourism Activities ....................................................................... 45

3.3.5

Marine Protected Areas .......................................................................................... 45

3.3.6

Shipwrecks.............................................................................................................. 45

3.3.7

Defence Practice Areas .......................................................................................... 45

3.3.8

Cultural Heritage ..................................................................................................... 45

3.3.9

Particular Issues or Sensitivities ............................................................................. 45

4.0

Risk Assessment .............................................................................................................................. 46

4.1

Overview ................................................................................................................................ 46

4.2 Methodology ........................................................................................................................... 46

4.3 Key Outcomes ........................................................................................................................ 61

4.3.1 Routine and Operational Discharges ...................................................................... 61

4.3.2

Noise ....................................................................................................................... 66

4.3.3

Positioning and Presence of the Rig ...................................................................... 67

4.3.4

Quarantine .............................................................................................................. 67

4.3.5

Contingency Plan and Management of Unplanned Operations ............................. 68

5.0

Objectives, Performance Standards and Relevant Documentation ................................................. 72

5.1 Overview ................................................................................................................................ 72

5.2

Objectives ............................................................................................................................... 72

5.3

Performance Standards ......................................................................................................... 72

5.3.1

Discharge of Drilling Fluid and Cuttings ................................................................. 72

5.3.2

Underwater Noise ................................................................................................... 73

5.3.3

Oil/Chemical Spill .................................................................................................... 73

5.3.4

Fuel (Diesel Spill) .................................................................................................... 73

5.3.5

Loss of Well Control ................................................................................................ 73

5.3.6

Quarantine .............................................................................................................. 73

5.3.7 Discharge of Domestic Wastes............................................................................... 73

5.4 Relevant Documentation ........................................................................................................ 73

6.0

Implementation ................................................................................................................................. 78

6.1 Environmental Policy .............................................................................................................. 78

6.2 Environmental Management Documentation ......................................................................... 78

6.2.1 Overview ................................................................................................................. 78

6.2.2 Chevron ABU OE Documentation .......................................................................... 78

6.2.3 Gorgon Gas Development and Jansz Feed Gas Pipeline Documentation ............ 79

6.2.4 Project-specific Documentation .............................................................................. 79

6.2.5 Project-specific Plans and Procedures ................................................................... 80

6.3

Environmental Management Measures ................................................................................. 80

6.3.1 Rig and Vessel Wastes, Discharges and Emissions .............................................. 80

6.3.2 Vertical Seismic Profiling ........................................................................................ 81


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Chevron Australia Pty Ltd Public Page vii


6.3.3

Air Emissions ........................................................................................................... 82

6.3.4

Quarantine and Ballast Water ................................................................................. 83

6.3.5

Onboard Storage and Handling of Chemicals ......................................................... 83

6.3.6

Interaction with Other Users of the Area ................................................................. 83

6.3.7

Resupply Operations ............................................................................................... 84

6.3.8

Well Control ............................................................................................................. 85

6.3.9

Emergencies and Accidental Discharges ................................................................ 86

6.4

Training and Inductions ........................................................................................................... 86

6.5

Responsibilities ....................................................................................................................... 87

6.5.1 Chain of Command .................................................................................................. 87

6.5.2 Roles and Responsibilities ...................................................................................... 87

6.6 Maintenance of Emergency Response and Marine Oil Pollution Plan ................................... 90

7.0

Auditing, Reporting and Review ........................................................................................................ 92

7.1

Auditing ................................................................................................................................... 92

7.1.1

Internal Auditing ....................................................................................................... 92

7.1.2

External Auditing ..................................................................................................... 92

7.2

Reporting ................................................................................................................................. 93

7.2.1 Compliance Reporting ............................................................................................. 93

7.2.2

Environmental Performance Reporting ................................................................... 93

7.2.3

Routine Internal Reporting....................................................................................... 93

7.2.4

Monitoring and Audit ................................................................................................ 93

7.2.5

Incident Response and Reporting ........................................................................... 94

7.2.6

Reportable Incidents ................................................................................................ 95

7.2.7

Recordable Incidents ............................................................................................... 96

7.2.8

Record Keeping ....................................................................................................... 96

7.3

Review of this Plan ................................................................................................................. 97

8.0 References ........................................................................................................................................ 98

Appendix 1 Identification of Marine Matters of National Environmental Significance .............. 104

Appendix 2

EPBC Act Protected Matters Report ..................................................................... 105

Appendix 3 Chevron Integrated Risk Prioritization Matrix ........................................................ 106

Appendix 4 Oil Spill Operational Response Plan (OSORP) ..................................................... 108

Appendix 5 Chevron Corporate Operational Excellence Policy 530 ........................................ 109

Appendix 6 Computer Modelling of Noise Generated by VSP Source .................................... 110

Appendix 7 Compliance Reporting Table ................................................................................. 111


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List of Tables

Table 1-1 Requirements of this Plan ........................................................................................................ 24

Table 2-1 Coordinates of the Development Wells .................................................................................... 31

Table 2-2 Gorgon Development Well Design Details ............................................................................... 32

Table 2-3 Gorgon Development Well Total Cuttings Volumes (per well) ................................................. 33

Table 2-4 SBM Composition ..................................................................................................................... 34

Table 3-1: EPBC Act Listed Threatened Species that may Occur within the Permit Area ...................... 39

Table 4-1 Summary of Environmental Risks, Management and Mitigation Measures ............................ 48

Table 4-2 NOVATEC Saraline 185V-based SBM Ecotoxicity Results for Western AustralianSpecies ................................................................................................................................ 61

Table 4-3 Component Assay Data ........................................................................................................... 69

Table 5-1 Objectives, Performance Standards and Relevant Documentation ......................................... 74

Table 6-1 Well Controls and Mitigation/Recovery Measures ................................................................... 85

Table 7-1 Incident Reporting Requirements ............................................................................................. 94

List of Figures

Figure 1-1 Location of the Gorgon Gas Field ........................................................................................... 20

Figure 1-2 Proposed Well and Manifold Locations ................................................................................... 21

Figure 1-3 Gorgon Development Manifold Locations: Associated Environmental and Socio-economic Sensitive Areas ................................................................................................... 22

Figure 1-4 Hierarchy of Gorgon Gas Development Environmental Documentation ................................ 27

Figure 1-5 Deliverable Development, Review and Approval Flow Chart ................................................. 30

Figure 2-1 Bathymetry at Manifold and Well Locations ............................................................................ 32

Figure 6-1 Gorgon Gas Development Drilling Organisation Chart ........................................................... 91


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Chevron Australia Pty Ltd Public Page 9


Terminology, Definitions and Abbreviations

Terms, definitions and abbreviations used in this document are listed below. These align withthe terms, definitions and abbreviations defined in Schedule 2 of the Western Australian GorgonGas Development Ministerial Implementation Statement No. 800 (Statement No. 800) and theCommonwealth Gorgon Gas Development Ministerial Approvals (EPBC Reference: 2003/1294

and 2008/4178).

C Degrees Celsius

3D Three-dimensional

ABS American Bureau of Shipping

ABU Australasia Business Unit

ADIOS Automated Data Inquiry for Oil Spills

AFMA Australian Fisheries Management Authority

AFZ Australian Fishing Zone

AHTSV Anchor Handling, Tug and Supply Vessel

ALARP As Low As Reasonably Practicable

Defined as a level of risk that is not intolerable, and cannot be reducedfurther without the expenditure of costs that are grossly disproportionate tothe benefit gained.

AMOSC Australian Marine Oil Spill Centre

AMSA Australian Maritime Safety Authority

Annulus The space between two concentric objects, such as between the wellboreand casing or between casing and tubing, where fluid can flow.

APASA Asia-Pacific Applied Science Associates

APPEA Australian Petroleum Production and Exploration Association

AQIS Australian Quarantine and Inspection Service

ARI Assessment on Referral Information (for the proposed Jansz Feed GasPipeline dated September 2007) as amended or supplemented from timeto time.

ARPA Automated Radar Plotting Aid

AS Australian Standard

AusRep Australian Ship Reporting

AusSAR Australian Search and Rescue

Ballast water Any water and associated sediment used to trim and stabilise a vessel.


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Bathymetric Relating to measurements of the depths of oceans or lakes.

bbl Barrel

Benthic Living upon or in the sea floor.

Bentonite clay Clay formed from volcanic ash which can absorb large amounts of waterand expands to many times its normal volume.

Biocide Any substance that can destroy living organisms.

Biota All the plant and animal life of a particular region.

Bioturbation The displacement and mixing of sediment particles by benthic fauna(animals) or flora (plants).

BOP Blow Out Preventer

BP Boiling Point

Bund An area of containment, such as a dam, wall, or other artificialembankment.

CaCl2 Calcium Chloride

CAMBA China-Australia Migratory Bird Agreement

Carbon Dioxide(CO2) Injection

System

The mechanical components required to be constructed to enable theinjection of reservoir carbon dioxide, including but not limited to

compressors, pipelines and wells.

CCSBT Commission for the Conservation of Southern Bluefin Tuna

CCTV Closed Circuit Television

CEFAS Centre for Environment, Fisheries and Aquaculture Science

Cetacean Various aquatic (mainly marine) mammals of the order Cetacea, (includingwhales, dolphins and porpoises) characterised by a nearly hairless body,front limbs modified into broad flippers and a flat notched tail.

CGR Condensate/Gas Ratio

CHARM Chemical Hazard Assessment and Risk Management

CO2 Carbon Dioxide

Coaming A raised rim or border around an opening, as in a ship's deck, designed tokeep out water.

CommonwealthMarine Areas

Zoned areas of waters of the sea, the seabed and the airspace above thewaters of the sea, defined under section 24 of the EPBC Act (Cth).

cP Centipoise; a unit of dynamic viscosity equal to 1 millipascal second

Cth Commonwealth of Australia


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D&C Drilling and Completion

dB Decibel; a unit to measure sound

dB re 1 Pa Decibels relative to one micro pascal; the unit used to measure the

intensity of an underwater sound

Deadman A function to a safe mode that is automatically activated if all power andcontrols are lost to the equipment.

DEC Western Australian Department of Environment and Conservation

DEH Former Department of the Environment and Heritage (now SEWPaC)

Demersal Living on the seabed or just above it.

DEWHA Former Commonwealth Department of the Environment, Water, Heritage

and the Arts (now SEWPaC)

Diurnal Daily

DMP Western Australian Department of Mines and Petroleum (formerly DoIR)

DNV Det Norske Veritas; independent foundation that provides services formanaging risk

DoIR Western Australian Department of Industry and Resources (now DMP)

DP Dynamic Positioning; a computer controlled system to automatically

maintain a vessel's position and heading by using her own propellers andthrusters

DP Class 2 Dynamic positioning equipment Class 2 has redundancy so that no singlefault in an active system will cause the system to fail. Loss of positionshould not occur from a single fault of an active component or systemsuch as generators, thruster, switchboards, remote controlled valves etc.but may occur after failure of a static component such as cables, pipes,manual valves etc.

DSM Drill Site Manager

EC50 Concentration or dose yielding biological effects in 50% of test species.

EIS/ERMP Environmental Impact Statement/Environmental Review and ManagementProgramme (for the Proposed Gorgon Gas Development datedSeptember 2005) as amended or supplemented from time to time.

EMP Environmental Management Plan

EP Environment Plan

EP Act Western Australian Environmental Protection Act 1986

EPA Western Australian Environmental Protection Authority


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EPBC Act Commonwealth Environment Protection and Biodiversity Conservation Act1999

EPBC Reference:2003/1294

Commonwealth Ministerial Approval (for the Gorgon Gas Development) asamended or replaced from time to time


Commonwealth Ministerial Approval (for the Jansz Feed Gas Pipeline) asamended or replaced from time to time.


Commonwealth Ministerial Approval (for the Revised Gorgon GasDevelopment) as amended or replaced from time to time.

EPCM Engineering, Procurement and Construction Management

EPS Environmental Performance Standard

ERP Emergency Response Plan

Finfish A term used to distinguish fish with fins and gills, from shellfish, crayfish,jellyfish, etc.

G&G Geology and Geophysics

g/m2 Grams per square metre

gal/100 bbl Gallons per 100 barrels

GDA94 Geocentric Data of Australia

GM General Manager

Gorgon GasDevelopment

The Gorgon Gas Development as approved under Statement No. 800 andEPBC Reference: 2003/1294 and 2008/4178 as amended or replacedfrom time to time.

GU Global Upstream

HAZID Hazard Identification

HAZOP Hazard and Operability Study

Helideck Helicopter platform

Helifuel Helicopter fuel

HES Health, Environment and Safety

HPU Hydraulic power unit

HSE Health, Safety and Environment

HTB High Temperature Blend

Hydrocarbons A large class of organic compounds composed of hydrogen and carbon.Crude oil, natural gas, and natural gas condensate are all mixtures ofvarious hydrocarbons.


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IMDG International Maritime Dangerous Goods

IMO International Maritime Organization

IMS Invasive Marine Species

Infauna Benthic fauna (animals) living in the substrate and especially in a soft seabottom.

IP Intellectual Property

ISO International Organization for Standardization

Isobath A line on a chart joining places of equal depth of water; a depth contour.

JAMBA Japan-Australia Migratory Bird Agreement

Jansz Feed GasPipeline

The Jansz Feed Gas Pipeline as approved in Statement No. 769 andEPBC Reference: 2005/2184 as amended or replaced from time to time.

kcal/h Kilocalories per hour

kg/m3 Kilograms per cubic metre

km Kilometre

L Litres

L/h Litres per hour

LAO Linear Alpha Olefin

lb Pound

LC50 Concentration or dose found to be lethal in 50% of a group of test species.

LMRP Lower Marine Riser Package

LNG Liquefied Natural Gas

LOEC Lowest Observed Effect Concentration

LOT Leak Off Test

m Metre

m/s Metres per second

m3 Cubic metres

Macrofauna Animals whose shortest dimension is greater than or equal to 0.5 mm andthat can be seen without the aid of magnification; includes polychaetes,snails and amphipods.

Macrophytes A large aquatic plant, visible to the unaided eye, that grows in or nearwater and is either emergent, submergent, or floating (e.g. kelp).


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Marine Facilities In relation to Statement No. 800 and EPBC Reference: 2003/1294 and2008/4178, the Marine facilities are the:

Materials Offloading Facility (MOF)

LNG Jetty

Dredge Spoil Disposal Ground

Offshore Feed Gas Pipeline System and the marine component of theshore crossing

Domestic Gas Pipeline.

Marine Turtles Sea turtles of families Cheloniidae (Green, Flatback, Hawksbill,Loggerhead and Olive Ridley) and Dermochelyidae (Leatherback).

MARPOL The International Convention for the Prevention of Pollution From Ships,1973 as modified by the Protocol of 1978.

Also known as MARPOL 73/78.

(MARPOL is short for marine pollution)

Metocean Meteorological and oceanographic conditions.

MFO Marine Fauna Observer

mg/L Milligrams per litre

Migratory Species Species listed as migratory under section 209 of the EPBC Act (Cth).

mm Millimetre

MMO Marine Mammal Observer

MMscf/day Million standard cubic feet per day. 1 MMscf/day = 1180 Sm3/h (Standardcubic metres per hour).

MOF Materials Offloading Facility

MOPP Marine Oil Pollution Plan

MSDS Material Safety Data Sheet. A widely used system for cataloguing

information on substances, such as chemicals, chemical compounds, andchemical mixtures. MSDS information may include instructions for thesafe use and potential hazards associated with a particular material orproduct.

MTPA Million Tonnes Per Annum

N/A Not Applicable

Nearshore Close to shore; or within 3 nautical miles of Barrow Island.

Neritic The neritic zone, also called the sublittoral zone, is the part of the ocean

extending from the low tide mark to the edge of the continental shelf, witha relatively shallow depth of


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NES [Matters of] National Environmental Significance, as defined in Part 3,Division 1 of the EPBC Act (Cth).

NGER Act Commonwealth National Greenhouse and Energy Reporting Act 2007

nm Nautical Miles

NOEC No Observable Effect Concentration

NPI National Pollution Inventory

NZS New Zealand Standard

OE Operational Excellence

OECD Organisation for Economic Co-operation and Development

OEMS Operational Excellence Management System

OIM Offshore Installation Manager

OPGGS (E)Regulations

Commonwealth Offshore Petroleum and Greenhouse Gas Storage(Environment) Regulations 2009

OPGGS Act Commonwealth Offshore Petroleum and Greenhouse Gas Storage Act2006

OSORP Oil Spill Operational Response Plan

Pelagic Living in the open sea rather than in coastal or inland waters.

PER Public Environmental Review

PerformanceStandards

Are matters which are developed for assessing performance, notcompliance, and are quantitative targets or where that is demonstrated tobe not practicable, qualitative targets, against which progress towardsachievement of the objectives of conditions can be measured.

PGPA Policy, Government and Public Affairs

Photic Zone The depth of the water in a lake or ocean that is exposed to sufficient

sunlight for photosynthesis to occur. The depth of the photic zone can begreatly affected by turbidity.

POB Persons on Board

ppm Parts per million


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Practicable Practicable means reasonably practicable having regard to, among otherthings, local conditions and circumstances (including costs) and to thecurrent state of technical knowledge.

For the purposes of the conditions of EPBC Reference: 2003/1294 and2008/4178 that include the term practicable, when considering whether

the draft plan meets the requirements of these conditions, theCommonwealth Minister will determine what is practicable having regardto local conditions and circumstances including but not limited topersonnel safety, weather or geographical conditions, costs,environmental benefit and the current state of scientific and technicalknowledge.

psi Pounds per square inch

QC Quality Control

RAAF Royal Australian Air Force

ROC Retention on Cuttings

ROKAMBA Republic of Korea-Australia Migratory Bird Agreement

ROV Remotely Operated Vehicle

SAFE Safety Analysis and Functional Evaluation

SBM Synthetic-based Mud

SBT Southern Bluefin Tuna

SCSSV Surface-controlled Subsurface Safety Valve

SEWPaC Commonwealth Department of Sustainability, Environment, Water,Population and Communities (formerly DEWHA)

Significant Impact An impact on a Matter of National Environmental Significance, relevant toEPBC Reference: 2003/1294, 2005/2185 and 2008/4178 that is important,notable or of consequence having regard to its context or intensity.

Slug Pit Tank for storing drilling fluid

SOPEP Shipboard Oil Pollution Emergency Plan

Statement No. 748 Western Australian Ministerial Implementation Statement No. 748 (for theGorgon Gas Development) as amended from time to time [superseded byStatement No. 800].

Statement No. 769 Western Australian Ministerial Implementation Statement No. 769 (for theJansz Feed Gas Pipeline) as amended from time to time.

Statement No. 800 Western Australian Ministerial Implementation Statement No. 800 (for theGorgon Gas Development) as amended from time to time.

Substrate The surface a plant or animal lives upon. The substrate can include bioticor abiotic materials. For example, encrusting algae that lives on a rockcan be substrate for another animal that lives above the algae on the rock.


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TAPL Texaco Australia Pty. Ltd.

TDF Terrestrial Disturbance Footprint

Threatened

Species

Species listed as extinct, extinct in the wild, critically endangered,

endangered, vulnerable or conservation dependent under section 178 ofthe EPBC Act (Cth).

Turbidity The cloudiness or haziness of a fluid caused by individual particles(suspended solids) that are generally invisible to the naked eye, similar tosmoke in air. The measurement of turbidity is a key test of water quality.

UK CAA United Kingdom Civil Aviation Authority

VMS Vessel Management System

VP Vice President

VSP Vertical Seismic Profile

WA Western Australia

WAFIC Western Australian Fishing Industry Council

WAPET West Australian Petroleum Pty Ltd.

WAPET Landing Proper name referring to the site of the barge landing existing on the eastcoast of Barrow Island prior to the date of Statement No. 800.

WBM Water-based Mud

WMP Waste Management Plan

WOMP Well Operations Management Plan


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Executive Summary

This document provides a Plan (Environment Plan (EP)) for managing the potential impacts of aproposed drilling program in Commonwealth waters of the North West Shelf, which is scheduledto commence mid 2011 and is anticipated to be completed by mid to late 2013. This EP fulfilsthe relevant requirements of Conditions 16A of the Variation Decision for the Gorgon Gas

Development (EPBC Reference: 2003/1294), Condition 3.2 of EPBC Reference 2003/1294 and2008/4178, as well as those of the Commonwealth Offshore Petroleum and Greenhouse GasStorage Act 2006(OPGGS Act).

Eight Gorgon Gas Development wells will be drilled within Exploration Permit WA-37-L byChevron Australia Pty Ltd (Chevron Australia) using the Atwood Ospreysemi-submersible rig.Environmental management for the drilling and completions program will be conducted inaccordance with this EP and a specific Waste Management Plan. This EP describes thefollowing:

the area of operations, the proposed drilling activities, and the expected time frame

the existing natural, social and economic environments of the region, including issues and

sensitivities particular to the drilling activities

the possible risks to the environment from both planned (normal) and unplanned (abnormal)operations

Chevrons Environmental Policy and the environmental performance objectives derived fromthe Policy

the standards and criteria that will be used to measure environmental performance

the Implementation Strategy, including key roles and responsibilities, that will be applied toachieve the programs environmental performance goals

a system for documenting, monitoring, and reviewing the success of the ImplementationStrategy, to facilitate improvement of environmental performance.

Assessment of the environmental risks and effects of the drilling program indicates that thelikely impacts are temporary and/or localised, and are limited to:

physical disturbance of the seabed and benthic communities from the anchoring of the rig,discharge of the cuttings, and drilling of wells

reduction in water quality from waste discharges (including drilling fluid, cuttings, greywater,and sewage wastes)

disturbance to marine macrofauna and benthic communities from the presence, artificiallighting, and/or movements of the rig, support vessels, and helicopters

disturbance to marine fauna species from noise and vibration emissions from the rig andvessels

reduction in air quality from atmospheric emissions resulting from the flaring of hydrocarbonsand engine emissions.

Due to the remote location of the drilling program and the comprehensive management that willbe implemented, risks to the environment are all considered to fall within the low or lowmediumcategory.


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1.0 Introduction

1.1 Proponent

Chevron Australia Pty Ltd (Chevron Australia) is the proponent and the person taking the actionfor the Gorgon Gas Development on behalf of the following companies (collectively known as

the Gorgon Joint Venturers):

Chevron Australia Pty Ltd

Chevron (TAPL) Pty Ltd

Shell Development (Australia) Proprietary Limited

Mobil Australia Resources Company Pty Limited

Osaka Gas Gorgon Pty Ltd

Tokyo Gas Gorgon Pty Ltd

Chubu Electric Power Gorgon Pty Ltd

pursuant to Statement No. 800 and EPBC Reference: 2003/1294 and 2008/4178.

1.2 Project

Chevron Australia proposes to develop the gas reserves of the Greater Gorgon Area (Figure1-1).

Subsea gathering systems and subsea pipelines will be installed to deliver feed gas from theGorgon and JanszIo gas fields to the west coast of Barrow Island. The feed gas pipelinesystem will be buried as it traverses from the west coast to the east coast of the Island, wherethe system will tie in to the Gas Treatment Plant located at Town Point. The Gas TreatmentPlant will comprise three Liquefied Natural Gas (LNG) trains capable of producing a nominalcapacity of five Million Tonnes Per Annum (MTPA) per train. The Gas Treatment Plant will alsoproduce condensate and domestic gas. Carbon dioxide (CO2), which occurs naturally in thefeed gas, will be separated during the production process. As part of the Gorgon GasDevelopment, Chevron Australia will inject the separated CO2 into deep formations belowBarrow Island. The LNG and condensate will be loaded from a dedicated jetty offshore fromTown Point and then transported by dedicated carriers to international markets. Gas fordomestic use will be exported by a pipeline from Town Point to the domestic gas collection anddistribution network on the mainland.

Proposed drilling activities in support of the Gorgon Gas Development will comprise eightdevelopment wells to be drilled within Permit Area WA-37-L. Drilling operations are scheduled

to commence in June 2011 and will extend until all the Gorgon wells are drilled and completed,which is anticipated to be by the end of 2013.

1.3 Location

The Gorgon gas field is located in Production Licence WA-37-L, in Commonwealth marinewaters of the North West Shelf, off Western Australia (Figure 1-1 andFigure 1-2). ProductionLicence WA-37-L is located approximately 130 km off the north-west coast of Western Australia,and 65 km north-west of Barrow Island. Barrow Island is located off the Pilbara coast 85 kmnorth-north-east of the town of Onslow and 140 km west of Karratha. The Island isapproximately 25 km long and 10 km wide and covers 23 567 ha. It is the largest of a group ofislands, including the Montebello and Lowendal Islands (Figure 1-3).


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Figure 1-1 Location of the Gorgon Gas Field


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Figure 1-2 Proposed Well and Manifold Locations


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Figure 1-3 Gorgon Development Manifold Locations: Associated Environmental andSocio-economic Sensitive Areas


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(Statement No. 769) and the Commonwealth Minister for the Environment and WaterResources on 22 March 2006 (EPBC Reference: 2005/2184).

This Plan covers the Gorgon Gas Development as approved under EPBC Reference:2003/1294 and 2008/4178.

1.5 Purpose of this Plan

1.5.1 Scope of this Environment Plan

This Plan has been prepared to ensure that drilling activities for the Gorgon Gas Development,as described in Section2.0,are conducted in a manner that protects environmental values andreduces impacts to the environment to as low as reasonably practicable (ALARP).

1.5.2 Requirements

For the proposed drilling program, this Plan satisfies the relevant requirements of Condition 16Aof the Variation Decision for the Gorgon Gas Development (EPBC Reference: 2003/1294) for

the Management of Offshore Impacts, which is quoted below:Prior to commencement of construction of offshore facilities in Commonwealth waters, theperson taking the action must submit for the Ministers approval a plan (or plans) formanaging the impacts of the action....

Offshore construction may not commence in Commonwealth marine areas until the plan isapproved.

This Plan also addresses the relevant requirements of Condition 3.2 of EPBC Reference:2003/1294 and 2008/4178. Table 1-1 summarises the specific requirements of the relevantconditions of EPBC Reference: 2003/1294 and where they are addressed in this Plan.

This Plan is also required under the Commonwealth Offshore Petroleum Gas and Greenhouse

Gas Storage Act 2006 (OPPGS Act)and associatedOffshore Petroleum Gas and GreenhouseGas Storage (Environment) Regulations 2009(OPGGS (E) Regulations), to be approved by theDesignated Authoritythe Western Australian Department of Mines and Petroleum (DMP).

This Plan is being submitted for approval only for the scope of works outlined in Section2.0. Inaccordance with Condition 16A of EPBC Reference: 2003/1294, approval of other plans tomanage the impacts of additional offshore construction activities will be obtained beforeconstruction commences for those specific activities.

The process for development, review and approval of this Plan is shown inFigure 1-5.

Table 1-1 Requirements of this Plan

MinisterialDocument

ConditionNo.

Requirement Section Referencein this Plan

EPBC Ref:2003/1294and2008/4178

3.2.1 Provide a description of the EPBC listed speciesand their habitat likely to be impacted by thecomponents of the action which are the subject ofthe plan.

Section3.2,Appendix1,andAppendix 2

EPBC Ref:2003/1294and2008/4178

3.2.2 Provide an assessment of the risk to these speciesfrom the components of the action the subject ofthat plan, relevant to the plan.

Section4.0 andAppendix 3

EPBC Ref:2003/1294and

3.2.3 Provide details of the management measuresproposed in relation to these species if it is arequirement of the condition requiring that plan.

Section6.3.2 andAppendix 6


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MinisterialDocument

ConditionNo.

Requirement Section Referencein this Plan

2008/4178

EPBC Ref:2003/1294

16A.1.i Design and construction of facilities to allow for thecomplete removal of all structures and components(except flowlines) above the sea floor

Section2.0

EPBC Ref:2003/1294

16A.1.ii Sea floor surveys around proposed flowline pathsand well sites to identify sensitive marineecosystems such as reefs, sponge beds and seagrasses and historic shipwrecks

Sections2.2.6,3.1.1,and4.3.3.1

EPBC Ref:2003/1294

16A.1.iii Selection of flowline paths and well sites to avoidimpacts on sensitive marine ecosystems andhistoric shipwrecks as referred to in 16A.1ii

Sections2.2.6 and3.2.1

EPBC Ref:2003/1294

16A.1.iv Establish baseline information to inform a risk-based approach to environmental managementand monitoring of action-attributable impacts towater quality, benthic flora and fauna and keystonespecies from the installation and operation ofmarine facilities.

Sections2.2.6 and3.2

EPBC Ref:2003/1294

16A.1.v A schedule of works Section2.0

EPBC Ref:2003/1294

16A.1.vi Managing the impacts on cetaceans, includinginteraction procedures for aircraft, supply andconstruction vessels that are consistent with part 8of the Environment Protection and BiodiversityConservation Regulations 2000

Sections4.3.3,5.3.2,and6.3.2

EPBC Ref:2003/1294

16A.1.vii Cetaceans sightings reporting Sections 7.2.4 and7.2.6

EPBC Ref:2003/1294

16A.1.viii Hydrotest fluid type, handling and disposal Not ApplicableseeSection2.1

EPBC Ref:2003/1294

16A.1.ix Ballast water management for internationalconstruction vessels arriving in Australia inaccordance with Australian Quarantine andInspection Service Australian Ballast WaterManagement Requirements

Sections4.3.4,5.3.6,6.3.4,and7.2.6.1

EPBC Ref:2003/1294

16A.1.x The use and disposal of drilling muds Sections2.2,4.3.1.1,6.3.1.1,and7.2.6.2

EPBC Ref:2003/1294

16A.1.xi The monitoring and disposal of produced formationwater, if it is planned to dispose of it to theCommonwealth marine environment

Not ApplicableseeSection2.1

EPBC Ref:2003/1294

16A.1.xii A plan for contingencies and the management ofunplanned events such as oil or gas leaks or spills

Sections4.3.5,5.3.3,5.3.4, 5.3.5,6.3.5,6.3.7,6.3.8,6.3.9,and

Appendix 4

Any matter specified in this Plan is relevant to the Gorgon Gas Development only if that matterrelates to the specific activities or facilities associated with that particular development.

The sections in this Plan which are noted in the above table to meet the conditions of EPBCReference: 2003/1294 and 2008/4178 shall be read and interpreted as only requiringimplementation under EPBC Reference: 2003/1294 and 2008/4178 for managing the impacts ofthe Gorgon Gas Development on, or protecting, the EPBC Act matters listed inAppendix 1


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1.5.3 Hierarchy of Documentation

This Plan will be implemented for the Gorgon Gas Development via the Chevron AustralasiaBusiness Unit (ABU) Operational Excellence Management System (OEMS). The OEMS is thestandardised approach that applies across the ABU in order to continuously improve themanagement of safety, health, environment, reliability and efficiency to achieve world-class

performance. Implementation of the OEMS enables the Chevron ABU to integrate itsOperational Excellence (OE) objectives, processes, procedures, values, and behaviours into thedaily operations of Chevron Australia personnel and contractors working under ChevronAustralias supervision. The OEMS is designed to be consistent with and, in some respects, gobeyond ISO 14001:2004 (Environmental Management SystemsRequirements with Guidancefor Use) (Standards Australia/Standards New Zealand 2004).

Figure 1-4 provides an overview of the overall hierarchy of environmental managementdocumentation within which this Plan exists. Further details on environmental documentationfor the Gorgon Gas Development are provided in Section6.1 of this Plan.


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Figure 1-4 Hierarchy of Gorgon Gas Development Environmental Documentation

Note: The above figure refers to all Plans required for Ministerial Statement No. 800. The Plans are only relevant to EPBC Reference: 2003/1294, if required for those Conditions ofthose approvals.


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1.5.4 Relevant Standards and Guidelines

The following standards and guidelines, including applicable legal, environmental, and otherrequirements, have been taken into account in the development of this Plan:

Code of Environmental Practice (Australian Petroleum Production and ExplorationAssociation [APPEA] 2008)

Commonwealth Quarantine Act 1908

Commonwealth Quarantine Regulations 2000

CommonwealthAustralian Maritime Safety Authority Act 1990

Commonwealth Environment Protection and Biodiversity Conservation Act 1999(EPBC Act)

Commonwealth Environment Protection (Sea Dumping) Act 1981

Commonwealth Historic Shipwrecks Act 1976

CommonwealthNative Title Act 1993

Commonwealth Offshore Petroleum and Greenhouse Gas Storage Act 2006(OPGGS Act)

Commonwealth Offshore Petroleum and Greenhouse Gas Storage (Environment)Regulations 2009 (OPGGS (E) Regulations)

Commonwealth Protection of the Sea (Prevention of Pollution from Ships) Act 1983

CommonwealthAustralian Heritage Commission Act 1975

Commonwealth Department of Resources, Energy and Tourism Guidelines for thePreparation of an Environment Plan

Western Australian Department of Industry and Resources (DoIR) Petroleum Guidelines

Drilling Fluids Management (DoIR 2006)

The principal international agreement governing petroleum operations in both State andCommonwealth waters is the United Nations Convention on the Law of the Sea 1982. Australiais also a signatory to a number of international conventions of relevance to the proposedproject:

Convention on the Conservation of Migratory Species of Wild Animals (Bonn Convention)

Convention on Wetlands of International Importance Especially as Waterfowl Habitat(RAMSAR)

International Convention on Oil Pollution Preparedness, Response and Co-operation 1990

United Nations Convention on the Law of the Sea 1982 (UNCLOS)

United Nations Framework Convention on Climate Change

International Convention for the Prevention of Pollution from Ships 1973, as modified by theProtocol of 1978 (MARPOL 73/78)

Protocol to International Convention on the Prevention of Marine Pollution by Dumping ofWaste and Other Matter 1972 (London Dumping Convention).

JapanAustralia Migratory Bird Agreement (JAMBA)

ChinaAustralia Migratory Bird Agreement (CAMBA)

Republic of KoreaAustralia Migratory Bird Agreement (ROKAMBA).


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1.5.5 Stakeholder Consultation

Consultation with stakeholders has been undertaken by Chevron Australia on a regular basisthroughout the development of environmental impact assessment management documentationfor the Gorgon Gas Development and Jansz Feed Gas Pipeline. This has includedengagement with the community, government departments, industry operators and contractors

to Chevron Australia via planning workshops, risk assessments, meetings, teleconferences, andthe PER and EIS/ERMP formal approval processes.

In December 2010, additional consultations specifically regarding the proposed drilling andcompletions program were undertaken. A detailed written description (letter) of the drillingprogram, including the water depths of the permit area, the distance of the permit area fromBarrow Island and North West Cape, the number of wells to be drilled and the specificcoordinates for each well location, was provided to each stakeholder. Attached to the letter wasa figure showing the permit areas, well locations, bathymetry, other oil and gas permit areas,and distances to land. This letter (with attached figure) was emailed to these stakeholders:

Australian Fisheries Management Authority (AFMA)

Australian Maritime Safety Authority (AMSA)

Western Australian Department of Fisheries

Commonwealth Department of Defence

Commonwealth Fisheries Association

Australian Southern Bluefin Tuna Industry Association

A. Raptis and Sons

JAMACLAN Marine Services

Northern Fishing Companies Association

TunaWest

Recfishwest

Western Australian Fishing Industry Council

Western Australian Northern Trawl Owners Association

Western Australian Seafoods.

The key outcomes of this consultation were that:

Low levels of commercial shipping traffic are expected near the permit area.

Southern Bluefin Tuna spawning occurs north of the survey area between September andApril with a peak in December through to March, and the Leeuwin Current may entrainjuveniles through the permit area during operations.

Fishing activity for the State fisheries is likely to be very low in the area of proposed drilling.

The Australian Hydrographic Office (AHO) (response through the Department of Defence)requires information on whether the wells are left suspended, or plugged and abandoned oncompletion of the drilling.

Chevron Australia will maintain communications with relevant agencies, fishery groups, and portauthorities to ensure that they are informed of any aspects of the drilling program that may

affect other users of the area.The process for development, review and approval of this Plan is shown inFigure 1-5.


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Figure 1-5 Deliverable Development, Review and Approval Flow Chart

1.5.6 Public Availability

This Plan will be made public as and when determined by the Minister under Condition 22 of

EPBC Reference: 2003/1294 and 2008/4178.


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2.0 Drilling Activities

2.1 Overview

As part of the Gorgon Gas Development, Chevron Australia proposes to conduct drilling andwell testing activities within Production Licence WA-37-L for eight development wells,. All

operations will be conducted in accordance with relevant Acts and Regulations to meet therequirements of the OPGGS Act. The wells will be drilled using the Atwood Oceanics PacificPty Ltd (Atwood)Atwood Ospreysemi-submersible rig.

Proposed drilling activities in support of the Gorgon Gas Development will comprise eightdevelopment wells to be drilled within Permit Area WA-37-L. Drilling operations are scheduledto commence in June 2011 and will extend until all the Gorgon wells are drilled and completed,which is anticipated to be by the end of 2013.

Table 2-1 Coordinates of the Development Wells

Well Name Latitude (GDA94) Longitude (GDA94) Water Depth (m)

GOR-1C 20 24 28.372 S 114 50 56.841 E 215

GOR-1D 20 24 28.611 S 114 50 57.734 E 215

GOR-1E 20 24 29.171 S 114 50 58.313 E 215

GOR-1F 20 24 30.019 S 114 50 58.543 E 215

GOR-2B 20 27 36.535 S 114 50 31.386 E 199

GOR-2C 20 27 37.095 S 114 50 31.964 E 199

GOR-3B 20 31 11.275 S 114 49 25.845 E 199

GOR-3C 20 31 11.835 S 114 49 26.424 E 199

To minimise environmental impact, and to maximise drilling efficiency, safety, and operationsmanagement, the batch drilling will follow this schedule of works:

At Manifold 3, the top-hole section on GOR-3B will be drilled and cased before the rig movesto GOR-3C. GOR-3C will then be drilled through to partial completion (cemented casingstrings) and well suspension. The rig will then move back over GOR-3B and partiallycomplete the wells through to suspension before moving to subsea Manifold 1.

At Manifold 1, the top-hole sections on all four wells (GOR-1C, GOR-1D, GOR-1E and GOR-1F) will be drilled before the rig commences partial completion and well suspension on GOR-1E, followed by GOR-1C, GOR-1D, and GOR-1F. The rig will then move to subseaManifold 2.

At Manifold 2, the top-hole sections of GOR-2B and GOR-2C will be drilled. Well GOR-2Cwill then be partially completed and suspended before the rig moves back to GOR-2B tocomplete the drilling of the well to completion.

Well GOR-2B will be the first well completed, following the batch drilling phase. The batchcompletion of the Gorgon wells will proceed in the reverse order in which they were drilled.Each well will be terminated at the seabed by a horizontal subsea tree. SeeFigure 1-2 for welland manifold locations. Coordinates of the proposed wells are given inTable 2-1.

The batch drilling phase for each well is scheduled for 52 days, and the batch completion phaseis scheduled for 38 days. The scheduled days are estimates and are exclusive of additionaltiming that could result from adverse weather, equipment delays, rig downtime or well problems

etc.

The program does not include any post-completion tie-in or other operations, and hence doesnot involve hydrotest fluid or produced formation water handling or disposal.


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Figure 2-1 Bathymetry at Manifold and Well Locations

2.2 Well Design and Drilling Details

The wells have been designed in accordance with Chevron Corporate and Chevron AustraliaStandards, accepted industry practices, and DMP regulatory requirements. Wells will besuitable for all conditions that might be expected during drilling operations.

2.2.1 Design

The eight Gorgon development wells will be designed as shown inTable 2-2 andTable 2-3. Allwells will be of similar design.

Table 2-2 Gorgon Development Well Design Details

Hole size Casing size Depth BelowSeabed

Length ofHole Section

Volume ofcuttings

Drilling Fluid

Inch mm Inch mm m m bbl m3

42 1067 36 914 70 70 590 95 Sea water with

high viscositysweeps


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Hole size Casing size Depth BelowSeabed

Length ofHole Section

Volume ofcuttings

Drilling Fluid

Inch mm Inch mm m m bbl m3

26 660 20 508 400 330 950 151 Sea water with

high viscositysweeps

17 444 14 340 1800 1,400 1549 246 Synthetic-basedMud (SBM)

13 343 10 244 3200 1,400 813 129 SBM

8 222 7 178 5200 2,000 540 86 SBM

Table 2-3 Gorgon Development Well Total Cuttings Volumes (per well)

Cuttings Volumes Volume (bbl) Volume (m3)

Water-based Mud (WBM) 1540 246

Synthetic-based Mud (SBM) 2902 461

Total 4442 707

The upper sections of each well (42 and 26 hole sections) will be drilled riserless, using seawater with high viscosity sweeps. The remaining sections of each well will be drilled with amarine riser and Blow-Out Preventers (BOP) installed and using a synthetic-based drilling fluid(SBM), namely NOVATEC.

Drilling will be conducted to a target depth of approximately 5200 m below the seabed. Coreswill also be taken in targeted reservoirs in the well.

Cuttings volumes provided in Table 2-3 are indicative of volumes to be generated anddischarged for each well.

2.2.2 Drilling Fluids and Chemical Additives

Shallower sections of the wells will be drilled using sea water with high viscosity gel sweeps.The remaining sections of the well will be drilled using SBM in a closed-fluid system. Theselected SBM NOVATEC, provided by MI Swacohas been chosen for improved safety,environmental, operational, and economic performance (reduced time on location, better wellcontrol).

NOVATEC is a Saraline 185V based SBM. This SBM has been assessed to be non-toxic toalmost non-toxic and has previously been approved by DMP for drilling operations in WesternAustralia (WA). Characteristics of the drilling fluids to be used during the drilling operations,including ecotoxicity information, are described briefly below.

2.2.2.1 Water-based Drilling Fluids (WBM)

The proposed WBM will be a sea water/high viscosity sweeps (bentonite) mixture, which isconsidered to have minimal environmental effect (see Section4.3.1.1).

2.2.2.2 Synthetic-based Drilling Fluids (SBM)

The preferred fluid system for the drilling program is the NOVATEC fluid system, previously

approved by DMP for other drilling operations in WA, which contains a Saraline 185V base fluid.According to the DMPstoxicity ratings system (DoIR 2006), the components of NOVATEC(whole mud) are considered non-toxic to almost non-toxic and biodegradable (see Section


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Manager (DSM) onboard. For SBMs, the target recovery will be


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practicable) any debris in the drilling area and to provide a record of the size and position of anycuttings piles (if present).

The results of the surveys will be included in close-out environmental reporting.

2.2.7 Logging

The wells will be evaluated with a standard wireline logging suite, including sidewall cores,formation samples, and, on some wells, Vertical Seismic Profile (VSP). The VSP acousticsource will consist of a 750 cubic inch three airgun array. The airgun array will generateacoustic pulses five times at 20 second intervals every five to seven minutes for each depthlevel, and is expected to take between six and 12 hours per well. The maximum noise levelexpected to be generated is approximately 195 dB re 1 Pa @ 1m. VSP operations will beundertaken in accordance with cetacean interaction procedures, discussed in Section6.3.2.

2.2.8 Well Testing and Clean-Up

The wells will be subject to a clean-up well flow test to 60 to 75 MMscf/day at the end of thecompletion phase, prior to production. Well flow clean-up is planned to be no longer than12 hours per well, commencing in daylight but possibly continuing into the night. Rates of flaredgas and liquids will be recorded, and reported as per the National Pollutant Inventory (NPI)requirements and the National Greenhouse and Energy Reporting Act 2007 (Cth) (NGER Act)guidelines (Commonwealth Government of Australia 2008).

2.2.9 Well Suspension and Completion

At the completion of the batch drilling phase of development, wells will be cased and cemented,and will be suspended (or, in the event a dry hole, plugged and abandoned) in accordance withthe requirements of the OPGGS Act and industry best practice. A tested retrievable packer willbe set in the well bore, which will later be recovered during the completion phase.

When all eight wells are batch drilled, the wells will be batch completed in the reverse order thatthey were drilled. After the Horizontal Trees have been fitted, and the BOPs and riser havebeen landed out, tubing will be run in the well, the reservoir zones will be perforated, and clean-up flows undertaken ready for production. The wells will be fitted with a surface-controlledsubsurface safety valve (SCSSV) designed to slam shut in the event of wellhead or treedamage. An exclusion zone will be established around the manifolds and subsea infrastructure.

Completion brine will be discharged during well completion when the fluid will be displaced fromthe well. Approximately 500 bbl of sodium bromide (solution of 27% mixed with fresh water) willbe discharged per well.

Seabed surveys of the well location will be conducted by ROV to check for (and recover wherepracticable) any debris in the vicinity of the well, and to provide a record of the size and positionof any cuttings piles (if present).

2.2.10 Marine and Support Operations

2.2.10.1 Rig and Support Vessels

The Atwood Osprey rig is a semi-submersible, moored drilling rig. The Atwood Ospreywasconstructed in the Jurong Shipyard in Singapore and was towed into Australian Commonwealthwaters for Chevron Australias drilling program in May 2011. TheAtwood Ospreyhas a 12-pointanchoring system, comprising three anchors off each corner of the main deck of the rig. Thefootprint of each anchor on the seabed is 5.5 m (length) by 6.0 m (wide).

The rig is supported by two dedicated Anchor Handling, Tug and Supply Vessels (AHTSV)supplied by Farstad Shipping, the Far Shogun and Far Saracen. Both support vessels areClass 2 Dynamic Positioning (DP2) vessels. The rig may also share, as required, supportvessels for the Atwood Eagle rig, namely the Maersk Supporter and the Maersk Searcher,mobilised for exploration drilling activities in nearby exploration permits. All support vessels willoperate out of the Port of Dampier.


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The two support vessels will be used primarily to supply the rig, support drilling operations, andtow the rig between drilling sites, but they will also provide search and rescue functions. Allsupport vessels will be fitted with Shipboard Oil Pollution Emergency Plan (SOPEP) equipmentin accordance with MARPOL 73/78 requirements.

The rig will be serviced by helicopters based on Barrow Island. Helicopter flight frequency will

be on average one per day and will primarily be used for passenger transfers/crew changes,and minor supplies. All crew changes for the rig will be conducted by helicopter, with rotationsscheduled every 21 to 28 days. The rig has the capacity for a maximum Persons on Board(POB) of 200 personnel, with an operational personnel capacity of 145 to 160 POB. Crewchanges for the support vessels will be conducted in the Port of Dampier, with rotationsscheduled every 28 to 35 days. The support vessels are capable of a maximum POB of40 personnel each, with an operational personnel capacity of 16 POB for each vessel.

2.2.10.2 Refuelling

Refuelling will be conducted for theAtwood Ospreyrig from the two AHTSVs in accordance withthe Atwood Diesel Fuel Oil Bunkering procedures outlined in the Atwood Osprey OperationsManual, Section 6.3 (in prep). Dedicated transfer hoses with dry break couplings and safety

breakaway fittings will be used. Pressure tests (120 psi hose integrity test) will be conductedprior to transfers to verify the integrity of the hoses and piping. Refuelling may occurapproximately twice a week for the duration of the drilling program.

2.2.11 Time Frame

The drilling program will commence in June 2011. Drilling each Gorgon well will takeapproximately 90 days (52 days drilling and 38 days well completion), including relocationbetween sites. The program is expected to continue until all wells are drilled and completed,which is anticipated to be by the end of 2013. Drilling operations will be conducted 24 hours aday.


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3.0 Existing Marine Environment

3.1 Physical Environment

3.1.1 Bathymetry and Seabed Features

The eight Gorgon development wells are located in waters off the Australian continental shelf,with water depths ranging from 199 to 215 m. These wells are located approximately 60 kmfrom Barrow Island and 155 km from the mainland (North West Cape is the closest point). Thenorthernmost portion of the Gorgon gas field is gently sloping and dissected by a north-west tosouth-east aligned ridge (Chevron Australia 2005). The southern extent of the gas field ischaracterised by deeply undulating valley terrain (Chevron Australia 2005). Benthic marinehabitats were surveyed for the Gorgon Gas Development using a combination of side-scansonar and video transect. Survey results indicated the seabed of the gas field would beexpected to comprise bioturbated soft sediments, and benthic habitats of the field are likely tobe widespread throughout the Montebello-Lowendal-Barrow Island region (Chevron Australia2005). Surveys conducted just north of the proposed drilling area in similar water depths (238to 264 m) showed the substrate to be predominantly silty muds (RPS 2009). There was

evidence of burrow holes in soft sediment, likely from worms, small fish or crustaceans, andoccasional sparse communities of crinoids, sponges and gorgonians associated with areas ofconsolidated sediments and scattered rubble (RPS 2009). Based on current knowledge, nosensitive ecosystems have been identified.

3.1.2 Metocean Conditions

The region is generally characterised by two seasons: summer (SeptemberApril) and winter(MayAugust) (Pearce et al.2003). The climate in winter is dominated by intense anti-cyclonicbelts (high pressure systems), which generate strong winds (predominantly from the east andsouth-east) and infrequent rain. Summer conditions are more variable, with varying winddirections (although south-westerly winds are the most common) (Pearce et al. 2003).

The area typically experiences a persistent winter swell of around 2 m, generated by lowpressure systems in the southern latitudes (Pearce et al. 2003). During winter, strong easterlywinds can also generate 2 m seas. Both swell and seas tend to be smaller during summer.

Tropical cyclones occur in the region, with an average of five per year (Bureau of Meteorology2011). According to the Bureau of Meteorology, the Australian region tropical cyclone seasonruns from 1 November to 30 April (Bureau of Meteorology 2011). Tropical cyclones areunpredictable in occurrence, intensity and behaviour, but are most common between Decemberand March, and can generate extreme seas and swell.

Water circulation in the area is influenced by the southward-flowing oceanic Leeuwin Current.The Leeuwin Current is strongest in winter, flowing steadily to the south-west at up to 0.3 m/s(Holloway and Nye 1985).

Tides are strongly semidiurnal, with four tide changes per day. The dominant tidal current flowsin summer are east-north-east and west-south-west, with speeds generally ranging from 0.1 to0.3 m/s (Pearce et al. 2003).

Near-surface water temperatures of the North West Shelf range from 31 C maximum insummer, to 22 C minimum in winter (Chevron Australia 2005), with an average of 26.8 C anda mixed layer of 35.7 m.(Brewer et al. 2007). The mean water temperature for depths between200 and 250 m is around 10 C (Chevron Australia 2003).

3.2 Marine Biological Environment

Condition 3.2.1 of EPBC Reference: 2003/1294 and 2008/4178 requires a description of theEPBC Act listed species and associated habitats likely to be impacted by the components of the


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action that is the subject of this Plan. The EPBC Act listed species and associated habitats aredescribed inAppendix 1.

Condition 3.2.2 of EPBC Reference: 2003/1294 and 2008/4178 requires an assessment of therisk to EPBC Act listed species (detailed inAppendix 1)from the components of the action. AnEPBC Act Protected Matters search was also conducted specifically for Permit Area WA-37-L

(Appendix 2).

3.2.1 Benthic Flora and Fauna

Marine biological surveys indicate that subtidal habitats near the Gorgon gas field, which lies in200 m of water, comprise soft, bioturbated sediments (Chevron Australia 2005). The benthos inthis area is well below the photic zone so there are no marine macrophytes (marine flora). Fineorganic particles settle from the water column to form deep silt and mud.

The sea floor at specific well locations is likely to be typical of those across the permit area andacross broad expanses of the North West Shelf, comprising predominantly unconsolidated softsediments inhabited by sparse communities of relatively large benthic species (crustaceans,molluscs, and sponges). Infaunal communities are likely to be predominantly smaller burrowing

invertebrates. Any areas of exposed hard substrate that occur may support more diverseassemblages, including deepwater filter-feeding organisms, such as hydroids and sponges.

Prior to the commencement of drilling, surveys, using ROV and/or other subsurface imagingtechniques, will be used to confirm the absence of significant environmental features andidentify any sensitive marine ecosystems at drilling locations. Specific well locations andflowline paths will be selected to avoid sensitive marine ecosystems, and wells will bedirectionally drilled from three subsea manifold locations, reducing the impact and footprint onthe seabed.

3.2.2 Macrofauna

The offshore environment of the permit area is typical of wide expanses of the continental slope

and does not represent habitat of particular significance for any macrofauna.Some marine migratory species with broad distributions, such as cetaceans, fish, sharks,marine turtles and seabirds, may traverse the permit area occasionally (CommonwealthDepartment of Sustainability, Environment, Water, Population and Communities [SEWPaC]2010a). Under the EPBC Act, nine species listed as Threatened and 16 listed as Migratory mayoccur in Permit WA-37-L (Table 3-1;Appendix 2). However, the permit area does not containrecognised critical habitat for any Threatened or Migratory fish, sharks, marine turtles,cetaceans, or seabirds.

Further details regarding the main fauna groups that might occur in the area are provided in thefollowing sections.

Table 3-1: EPBC Act Listed Threatened Species that may Occur within the Permit Area

Common Name Scientific Name EPBC Act Status

Fish

Whale Shark Rhincodon typus Vulnerable; Migratory

Longfin Mako Shark Isurus paucus Migratory

Shortfin Mako Shark Isurus oxyrinchus Migratory

Reptiles

Flatback Turtle Natator depressus Vulnerable; Migratory

Green Turtle Chelonia mydas Vulnerable; Migratory

Hawksbill Turtle Eretmochelys imbricata Vulnerable; Migratory


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Common Name Scientific Name EPBC Act Status

Leatherback Turtle Dermochelys coriacea Vulnerable; Migratory

Loggerhead Turtle Caretta caretta Endangered; Migratory

Birds

Southern Giant-Petrel Macronectes giganteus Endangered; Migratory

Mammals

Antarctic Minke Whale Balaenoptera bonaerensis Migratory

Blue Whale Balaenoptera musculus Endangered; Migratory

Brydes Whale Balaenoptera edeni Migratory

Humpback Whale Megaptera novaeangliae Vulnerable; Migratory

Killer Whale Orcinus orca Migratory

Sperm Whale Physeter macrocephalus Migratory

Spotted Bottlenose Dolphin(Arafura/Timor Sea populations)

Tursiops aduncus Migratory

3.2.2.1 Fish

A number of sharks and pelagic finfish, including mackerel, tuna and billfish, occur in the watersof the North West Shelf and would be expected to occur in the permit area. The deep offshoreenvironment of the permit area is typical of the continental slope of north-western Australia andis not expected to represent habitat of particular significance to sharks and finfish.

Whale Sharks have a broad distribution in tropical and warm temperate seas. They feed onphytoplankton, macro-algae, plankton, krill and small nektonic life, such as small squid orvertebrates. Whale Sharks undertake a well-known annual migration to aggregate at NingalooReef (140 km from the closest development well) between March and July each year (Wilson etal. 2006). Yearly numbers of Whale Sharks at Ningaloo Reef are estimated to vary from 200 to400 individuals. This seasonal aggregation is thought to be linked to localised seasonal peaksof productivity, likely associated with a mass coral spawning event that occurs around March toApril each year. After July, the Whale Sharks disperse widely, mainly in a north-east directiontowards Indonesian waters. Whale Sharks are expected to occur only in very low numberswithin the permit area, due to the distance between the proposed wells and Ningaloo Reef.

The Longfin Mako Shark is a widely distributed, but rarely encountered, oceanic tropical shark.This species can grow to just over 4 m and is found in Western Australian waters north ofGeraldton. The Shortfin Mako Shark is a pelagic species with a circumglobal, wide-ranging,oceanic distribution in tropical and temperate seas (Mollet et al. 2000), and is widespread inAustralian waters.

Given their wide-ranging habitat and highly transient nature, Shortfin and Longfin Mako Sharks

may occur within the permit area. However, there are no bathymetric features or aggregationareas of importance for these species within the permit area. Therefore, these species are onlylikely to occur in very low numbers.

3.2.2.2 Seabirds

The Southern Giant-petrel is listed as Endangered under the EPBC Act and may be found in thepermit area. The Southern Giant-petrel is widely distributed; it breeds in sub-Antarctic watersduring the summer, while in winter most disperse north from 50 S to the Tropic of Capricorn(Environment Australia 2001).

There are no important feeding grounds known for this species near the permit area, and giventhe distance from land, foraging activity is likely to be low. Due to the widespread distribution of

the Southern Giant-petrel, numbers at any given location are likely to be low.There are no islands or other areas of known seabird breeding significance, or importantfeeding grounds for seabirds, within or close to the permit area.


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3.2.2.3 Reptiles

Five species of marine turtles may occur in the permit area: Flatback, Green, Hawksbill,Leatherback and Loggerhead Turtles.

Flatback Turtles are found only in the tropical waters of northern Australia, Papua New Guinea,and Irian Jaya. All recorded nesting beaches are in Australia (Limpus et al. 1989). The

Kimberley region of Western Australia, Cape Dommett, and Lacrosse Island are importantnesting areas (Bowlay and Whiting 2007). The nearest Flatback Turtle aggregation and nestingsites are located on Barrow Island (SEWPaC 20

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