Nerites Season 2 MC3D MSS
|Activity type||Seismic survey|
|Submitted by||TGS-NOPEC Geophysical Company Pty Ltd|
|Submission date||08 September, 2014|
|Decision date||23 October, 2014|
|Link to previously accepted EP|
Ms Tanya Johnstone
The geophysical company TGS-NOPEC Geophysical Company Pty Ltd (TGS) proposes to acquire a multi client three-dimensional (MC3D) marine seismic survey (MSS) within the Great Australian Bight (GAB), in the South-west Marine Region (SWMR).
The proposed Nerites Season 2 MC3D MSS area is located entirely within Commonwealth waters in the Ceduna sub-basin south of South Australia (SA). At the closest point, the survey area is located ~190 km west of the Eyre Peninsula, 270 km south-west from Ceduna and 180 km from the nearest mainland coastline (see Figure 1.1). The water depths in the operational area are in the range of ~750 to 3,500 metres, with the shallowest water depths situated along the north-eastern boundary.
During the proposed activities, the survey vessel will traverse a series of pre-determined sail lines within the Nerites Season 2 MC3D MSS full fold survey area at a speed of ~8 - 9 km/hr. As the vessel travels along the survey lines a series of noise pulses (approximately every 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 12 solid streamers (cables), with a maximum length of ~8 km. The seismic cables are towed side-by-side and the spacing will be 120 m between each cable. The seismic energy source tow depth will be 7.5 m (+/-0.5 m) and the cable tow depth will be 12 – 30 m (+/-1 m). The operating pressure for the seismic energy source will be approximately 2,000 psi and the source will be deployed in two arrays, each with a maximum volume of 4,100 cubic inches (cui). These arrays will be activated alternately, every 25 m along each acquisition line (i.e. 50 m per array).
Phase II of the Nerites MC3D MSS will be acquiring data in the period November 2014 to approximately June 2015. The Nerites Season 2 MC3D MSS will overlap Phase II of the Nerites MC3D MSS. This means that during the period January to June 2015 there will be two seismic survey vessels acquiring data concurrently within the overall Nerites operational area.
Note: This information has been extracted from the EP Summary. Please refer to the attached EP Summary for more information.