The Benefits of High-Resolution Full Waveform Inversion over the Scarborough Field Western Australia

The Scarborough gas field, located in WA-1-R and WA-62-R on the North West Shelf, Australia was discovered in 1979. The field is covered by the Scarborough 3D seismic survey acquired in 2004, but further appraisal remained difficult due to poor resolution and distortions from polygonal faulting and shallow gas in the overburden.

It was proposed that Full Waveform Inversion (FWI) could be used to derive a high frequency velocity model which when used in conjunction with a hi-resolution depth migration could correctly flatten the distorted gas water contact without need to resort to interpretation.

A test swath was initially reprocessed to determine firstly if the short cable would be long enough to adequately update the reservoir, secondly to determine the required frequency to flatten the contact and lastly to assess whether it would be possible to accelerate the processing by reducing the requirement for tomography. The success of the test resulted in full reprocessing of the full field.

In this paper we demonstrate that pre-stack depth migration with an FWI/tomography derived high resolution model results in a significant improvement in the seismic data quality over the Scarborough field in a shorter timeframe than conventional tomography.

The benefits of high-resolution full waveform inversion over the Scarborough field Western Australia