The Zeppelin 3D rocks the Vulcan sub-basin

Abstract

In January 2012, the storm clouds of Tropical Cyclone Iggy were gathering over the Timor Sea as production of the 500km2 Zeppelin 3D seismic survey began in the Vulcan sub-basin permits AC/P 50 and AC/P 51. Despite the high seas and the adoption of a conventional approach towards acquisition, the Zeppelin 3D appears to have set a new benchmark for seismic data quality in the Vulcan sub-basin, which has traditionally been considered a 'difficult data area'. Reprocessing some of the overlapping legacy Onnia 3D seismic suggests that much of the imaging improvement stems from a similar approach to multiple suppression to that used successfully in other 'difficult' Australian basins. The combination of shallow water demultiple, SRME and gap deconvolution followed by a stratigraphically-controlled velocity analysis appears to account for much of the improvement. Shooting in the (dominant) dip direction also appears to have helped although had we applied 3D SRME this might have been rendered less important. Using the reprocessed Onnia 3D and the Zeppelin 3D, our seismic interpreters have been able to develop a detailed structural model which underpins the distribution of fault bend fold related prospectivity. Enhanced resolution enables sequence stratigraphy to be delineated and low-stand fan leads identified. Seismic amplitudes also provide strong indications of reservoir sand geometries although porefill indications are expected to remain difficult to resolve. A series of structures within 3 separate plays (Triassic, Jurassic and Cretaceous) define a significant increase in the assessed oil and gas volumetric potential thereby justifying the early investment in seismic.