Shearwater Geoservices is carrying out a 2500 km 2 3D seismic survey in the Otway Basin, west of King Island, off the south coast of Australia.
Shearwater Geoservices is carrying out a 2500 km2 3D seismic survey in the Otway Basin, west of King Island, off the south coast of Australia.
Using the vessel Geo Coral for client ConocoPhillips, Shearwater will shoot the Sequoia MSS 3D seismic survey for the t/49P joint venture of ConocoPhillips and 3D Oil T49P. Helping to high-grade gas prospects for potential drilling.
The survey is expected to take 60 days between the middle of August and the end of October 2021.
Under the terms of the farmout agreement, ConocoPhillips is contracted to acquire a minimum of 1580 km2 of 3D seismic data at no expense to the company. The proposed increase in size of the acquisition area will provide coverage of all leads within the T/49P Permit and tie in with the previously acquired Flanagan 3D seismic survey.
The seismic acquisition follows the approval of the environmental plan by Nopsema (National Offshore Petroleum Safety and Environmental Management Authority).
According to Nopsema, water depths in the survey area range from 70 m to 1000 m, with 91% of the survey area being in water depths of less than 150 m. At its nearest points, the survey area is located 23.5 km from the west coast of King Island and 26 km from the Victorian coast.
The survey vessel will acquire the seismic data by towing three acoustic source sub-arrays operating alternatively, one discharging as the others recompress. The lateral distance between each of the sources will be 25 m to 37.5 m. The source volume will be a maximum of 3480 cubic inches with an operating pressure of 2000 pounds per square inch (psi). There will be 12 to 18 hydrophone ‘streamer’ cables approximately 6100 m long.
The vessel will sail back and forth across the acquisition area along 48 sail lines (based on a 14-streamer configuration) that will vary in separation from 500 m to 900 m. The survey will use ConocoPhillips’ Compressive Seismic Imaging (CSI) technology, which means that while the overall width of the streamer configuration remains consistent, the internal streamer separation will vary between 25 m and 100 m with a non-uniform interval distribution. Using CSI technology means that the survey can sail fewer line kilometres and use fewer streamers and acquire the seismic data quicker than a conventional seismic survey, said Nopsema.
Upon completion of the acquisition, processing and interpretation of the survey, the T/49P joint venture will high grade prospects for potential drilling.
ConocoPhillips Australia is the operator of the T/49P joint venture with an 80% interest in the T/49P permit and 3D Oil with a 20% interest.
