Octanex N.L. announced today that the Rissa 3D seismic survey, located within the WA-422-P permit, has been completed. The Rissa survey is the first of three new 3D seismic surveys currently being acquired in the Company’s Southern Bonaparte Basin permits.
The 3D seismic surveys are being acquired within three of the Company’s eight Southern Bonaparte Basin permits. The Company’s wholly-owned subsidiary, Goldsborough Energy Pty Ltd, holds a 100% participating interest in two of the permits (WA-07-P and WA-420-P), where surveys are still to be acquired, and a 60% interest in the third permit, WA-422-P, where the Rissa survey has just been completed.
These new 3D seismic surveys follow the successful acquisition (during November 2011) of three 2D seismic surveys in other of the Company’s Southern Bonaparte Basin permits. As with the completed 2D surveys, Seabird Exploration FZ LLC is carrying out the 3D surveys using the acquisition vessel, “Voyager Explorer”. The Rissa survey acquired approximately 331 km2 of new 3D seismic data and, like the 2D surveys, it was completed within budget. The amount of 3D data acquired by the Rissa survey exceeds the WA-422-P permit’s Year 2 and Year 3 work obligations of a combined 300 km2 of new 3D data.
The Rissa 3D survey area is located on the northern end of the Londonderry High, which is seen as a potential natural focus for oil migration.
To the north of the Rissa survey area there are several oil fields (Kuda Tasi, Coralina, Laminaria, Jahal/Buffalo and Kitan); while the presence of residual oil columns in exploration wells within and to the south of the survey area indicates the existence of an oil migration route through the survey area.
Leads identified on vintage 2D seismic data possess similar west to east oriented horsts and tilted fault blocks to those in the oil discoveries to the north. There are two wells within the Rissa 3D survey area that will be utilised to calibrate the new 3D data; Fulica-1 and Kittiwake-1/ST1. Fulica-1 was drilled on a large structure which was found to have a residual oil column in Early Cretaceous, Sandpiper Formation sandstones. From the poor resolution vintage 2D seismic, it is uncertain if this well tested a valid trap.
Kittiwake-1/ST1 tested a smaller tilted fault block structure. It found an 11m residual oil column at the top of thick Late Jurassic, Tithonian submarine fan sandstones of the Lower Sandpiper Formation and oil shows in the overlying Early Cretaceous Upper Sandpiper Formation sandstones. The well did not reach the Jurassic target Elang and Plover formations, although at the time the operator of the well thought it had. The poor resolution of the vintage 2D restricts clear definition of trap closure and cross fault seal juxtaposition. Hence there was a need to acquire a modern 3D seismic dataset to better resolve the leads within the survey area at the target reservoirs of the Early Cretaceous Sandpiper sandstones and Jurassic Elang and Plover formations.
[mappress] Offshore Energy Today Staff, January 16, 2012; Image: Seabird