ZEEKOET MC3D MARINE SEISMIC SURVEY ENVIRONMENT PLAN: PUBLIC SUMMARY This summary of the Environment Plan for the Fugro Zeekoet MC3D marine seismic survey, which will be acquired in the northern Bonaparte Basin offshore from Western Australia (WA), has been submitted to the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA), to comply with Regulations 11(7) and 11(8) of the Offshore Petroleum and Greenhouse Gas Storage (Environment) Regulations 2009. INTRODUCTION The geophysical company Fugro proposes to undertake a multi-client three-dimensional (MC3D) marine seismic survey (Zeekoet MC3D MSS), in the northern Bonaparte Basin offshore from northern WA. The Zeekoet MC3D MSS will be comprised of a maximum of 3,809 square kilometres (km2) of 3D seismic acquisition, and ~50 line kilometres of 2D seismic acquisition, in Petroleum Exploration Permits WA-446-P, NT/P80 and adjacent vacant acreage (Figure 1). The Zeekoet MC3D MSS is scheduled to occur in the period between May and August 2012 and is expected to be of ~75 days duration. COORDINATES OF THE PROPOSED ACTIVITY Boundary coordinates for the survey area (Figure 1) are provided in Table 1. Table 1: Zeekoet MC3D MSS survey area Latitude (S) Longitude (E) Degrees Minutes Seconds Degrees Minutes Seconds 11 54 50.52 127 41 38.05 11 34 20.67 127 41 23.59 11 25 00.01 127 57 22.21 11 59 31.01 128 19 50.00 11 59 54.87 128 19 49.99 12 12 51.13 128 19 49.99 12 12 50.96 128 12 06.11 12 06 31.31 128 07 27.50 12 05 23.41 127 48 19.29 Datum: WGS84 The Zeekoet MC3D survey area is situated at a minimum distance of ~205 km from the north Kimberley coastline, at Cape Londonderry. The survey area is located in Commonwealth waters, ~250 km north-east of East Holothuria Reef (in WA State waters), and 185 km west of Bathurst Island (in NT waters). The north- west boundary of the survey area is situated ~36 km south-east of the southern boundary of the Joint Petroleum Development Area (JPDA). The survey area is bisected by the WA/NT jurisdictional boundary in Commonwealth waters (Figure 1). Water depths in the survey area range from ~50-125 m. There are no shallow shoals or emergent features (water depths <30 m) within the survey area. Fugro Zeekoet MC3D Marine Seismic Survey Page 1 Environment Plan Public Summary Figure 1: Location map – Zeekoet Multi Client 3D marine seismic survey Fugro Zeekoet MC3D Marine Seismic Survey Page 2 Environment Plan Public Summary DESCRIPTION OF THE PROPOSED ACTIVITY The Zeekoet MC3D MSS is scheduled to occur in the period between May and August 2012 and is expected to be of ~75 days duration. Timing of commencement is dependent on fair sea state conditions suitable for marine seismic acquisition, the availability of the survey vessel for conducting the survey, and granting of approvals from the appropriate government bodies. During the proposed activities, the survey vessel will traverse a series of pre-determined sail lines within the operational area at a speed of ~8-9 km/hr. As the vessel travels along the survey lines, a series of noise pulses (every 8-10 seconds) will be directed down through the water column and seabed. The released sound is attenuated and reflected at geological boundaries and the reflected signals are detected using sensitive microphones arranged along a number of hydrophone cables (streamers) towed behind the survey vessel. The reflected sound is then processed to provide information about the structure and composition of geological formations below the seabed in an attempt to identify hydrocarbon reservoirs. The seismic array will comprise of a maximum of ten solid streamers with a maximum length of 6 km. Streamer spacing will be 100 m, and line spacing will be 500 m. The source (airgun array) tow depth will be 6 m (+/- 1 m) and the streamer tow depth will be 7 m (+/- 1 m). The operating pressure for the airgun array will be ~2,000 psi. The airgun array will consist of two sub-arrays, each with a maximum volume of ~3,200 cui. These sub-arrays will be fired alternately, with a shotpoint interval of 25.0 m vertical distance. The source produces sound pulses within a few metres in the order of 210-220 dB re 1μPa (sound pressure level – SPL) at frequencies extending up to ~128 Hz. These sound pulses are expected to decrease to sound exposure levels (SEL) in the order of 160 to 170 dB re 1µPa2.s within 1 km of the source and ~155 dB re 1µPa2.s within 2 km, dependent on the sound propagation characteristics of the area. Fugro proposes to conduct the Zeekoet MC3D MSS using a purpose-built seismic survey vessel. The specific survey vessel for this survey is yet to be determined—it could be either the Geo Atlantic or possibly the Geo Coral. In either case, the vessel will have all necessary certification/registration and be fully compliant with all relevant MARPOL and SOLAS convention requirements for a vessel of this size and purpose, including a Shipboard Oil Pollution Emergency Plan (SOPEP) in accordance with Regulation 37 of Annex I of MARPOL 73/78. The survey vessel will travel within the survey area at an average speed of 4.5 knots (~8.3 km per hour). A support vessel will accompany the seismic survey vessel to maintain a safe distance between the survey array and other vessels, and to manage interactions with shipping and fishing activities, if required. The specific support vessel for this survey is yet to be determined—it is likely to be the Cassandra VI if the Geo Atlantic is selected as the survey vessel. The support vessel will also re-supply the survey vessel with fuel and other logistical supplies. The support vessel will have a crew of ~15 personnel, and will have an implemented and tested SOPEP in place. During the survey, it is likely that the survey vessel will be refuelled at sea using the support vessel, either within or immediately adjacent to the survey area. At sea refuelling will only take place during daylight hours, and will not take place within a distance of 25 km from any emergent land or shallow water features. Fugro Zeekoet MC3D Marine Seismic Survey Page 3 Environment Plan Public Summary DESCRIPTION OF THE RECEIVING ENVIRONMENT The proposed Zeekoet MC3D survey area is located within the Joseph Bonaparte Gulf Basin, which is one of three sub-systems that constitute the Joseph Bonaparte Gulf system of the North Marine Region (NMR). Physical Environment The climate of the NMR is tropical monsoonal, with two distinct seasons, a summer wet season which occurs broadly between October and March, and a winter dry season, between April and September. The winters are influenced by easterly winds generated over inland Australia, resulting in dry and warm conditions, with very little rainfall and low relative humidity. The high humidity and thunderstorm activity of the wet season is caused by steady west to north-west winds, bringing moisture from the Timor Sea. Cyclones may occur in the region between December and April, resulting in severe storms with gale force winds. Typically, cyclones form south of the equator in the Timor or Arafura Seas when sea temperatures are greater than 26.5°C. Cyclones may move in any direction; however, the majority of past cyclones have moved over the northern Joeseph Bonaparte Gulf overlapping, or north of the Zeekoet MC3D survey area. On average, the Joseph Bonaparte Gulf receives ten cyclones per decade. The Joseph Bonaparte Gulf is protected from swell generated in the Southern Ocean, therefore swells affecting the area are limited to those generated by cyclones or prolonged strong winds. Sea waves, which are usually short period (1–8 second) waves, are generated by local synoptic winds and reflect wind directionality. Persistent strong winds capable of generating significant seas are generally associated with the south-easterly trade winds which dominate during winter or dry season months. However, the small south-easterly fetch is expected to limit the development of large seas throughout northern Joseph Bonaparte Gulf. Larger seas typically occur during the winter, from June to August. The period of calmest seas occurs from April to May. Tides in the Joseph Bonaparte Gulf are semi-diurnal with two high and two low tides per day. The tidal wave propagates in from the Timor Sea and circulates around an amphidromic point located offshore from Cape Londonderry. As a result, there is considerable variation in the tidal range along the north-west Kimberley coast and within the Gulf. Joseph Bonaparte Gulf is a broad and relatively shallow embayment with a coastline dominated by sand and mud flats, tidal creeks and estuaries of major river systems. Major inputs of fine silt sediments from the Ord, Victoria and Keep River systems occur during the wet season creating vast areas of high turbidity, particularly in the southern part of the Gulf. The sediments are deposited to form sand bars and mud flats that are the source of high turbidity throughout the year as sediments are resuspended by tidal movements. Consequently, high turbidity levels occur in the lower region of the Gulf throughout the wet season and during phases of high tidal variation (spring tides) during both the wet and dry seasons. The survey area for the Zeekoet MC3D survey includes two Key Ecological Features identified during the NMR bioregional planning process: 1. Carbonate banks in the Joseph Bonaparte Gulf. 2. Pinnacles of the Bonaparte Basin. Carbonate banks and shoals consist of a hard substrate with flat tops and steep sides that rise from water depths of between 150 and 300 m.