Submarine Channels Characterization using Seismic Attribute Analysis: A
Case Study from Browse Basin, Offshore Australia
Abstract
CHALLENGES Submarine channels, erosional features on the world’s
continental margins, are of great interest as they prove to be a
prolific reservoir around Gulf of Mexico, offshore Brazil and western
coast of Africa. The main challenge is to highlight the channels and
extract them as 3D objects from 3D-seismic data, as conventional
approach to delineate and map submarine channels in current data set is
difficult owing to presence of subtle thin submarine channels.
METHODOLOGY This 3D-seismic survey from Poseidon 3D prospect of the
Browse Basin spans an area of 4070 km with an orientation of 310° North.
Submarine channels are present in the Late Cretaceous Woolaston
formation. Generalized Spectral Decomposition and Sweetness attributes
have been used in this study to identify submarine channels. Generalized
Spectral Decomposition attribute volumes were generated at different
frequencies to identify some of the resolved channels. The Sweetness
attribute, on the other hand, was helpful in distinguishing other
channels based on the amplitude envelope and instantaneous frequency.
The Sweetness attribute, after blending with Generalized Spectral
Decomposition attribute, was used for Geobody (3-D objects) extraction
from the seismic data. Significant enhancement of channels and
suppressing background features was accomplished by controlling the
opacity of the volume. It was followed by extraction and editing of
Geobodies. RESULT AND CONCLUSION The current data set in Browse basin
has up to 10 submarine channels in Cretaceous, most of them being subtle
and difficult to map in 3D-seismic data. An alternate methodology to
characterize submarine channels by using Generalized Spectral
Decomposition and Sweetness attribute helped to mitigate the challenge.
Generalized Spectral Decomposition attribute could delineate some
submarine channels that got tuned at specific frequencies. The Sweetness
attribute was helpful in distinguishing other channels using the
amplitude envelope and instantaneous frequency. Further, the process of
extracting submarine channels as ‘Geobodies’ from seismic volume, proved
to be very valuable as it can be directly used for volumetric estimation
of prospects. Thus, the methodology discussed in this study can be used
as a reference to characterize and quantify submarine channels.