Activity Description and Location
CGG proposes to conduct multi-client three-dimensional (MC3D) marine seismic surveys within the Browse and Bonaparte Basins offshore from Western Australia (WA). The Gravis MC3D MSS polygon is located ~132 km from the mainland coastline of the west Kimberley coastline (Cape Voltaire), and ~44 km southeast of Ashmore Reef Commonwealth Marine Reserve. Browse Island is located ~63 km to the southwest of the polygon. Water depths across the polygon are ~25 to 525.
CGG proposes to conduct individual surveys within the Gravis MC3D MSS using a purpose-built seismic survey vessel. A support vessel will accompany the survey vessel. The survey vessel may be refuelled at sea 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. 
Operational Details
The Gravis MC3D MSS is a typical 3D survey similar to most others conducted in Australian marine waters (in terms of technical methods and procedures). No unique or unusual equipment or operations are proposed.
During the proposed activities, the survey vessel will traverse a series of pre-determined sail lines within the survey area at a speed of ~8-9 km/hr. The operating pressure for the airgun array will be ~ 2,000 psi with a maximum volume of ~4,433 cui and will produce at source sound pulses in the order of 242 dB re 1 µPa-m, at frequencies up to~200 Hz.
Timing
CGG plans to commence the Gravis MC3D MSS no earlier than Q2 2015. Although the Gravis MC3D MSS is expected to have an actual acquisition period of no more than 12 months, the individual surveys may be conducted in phases over a period of two (2) years.