Seismic Geomorphology and Characterization of Deep Water Architectural Elements and its Applications in 3-D modeling: A Case of Study, North Carnarvon Basin Australia

Abstract

Abstract

Analysis of a high resolution 3D seismic volume from Cenozoic strata in the offshore of North Carnarvon basin, Australia has revealed fine details of deep water architectural elements, including their dimensions and position on the slope. Four main groups of architectural elements were identified and measured within eight stratigraphic sequences interpreted in the studied area: (1)erosive channel-fills, (2)channel-levee complexes, (3)mass transport deposits, and (4) sand fan lobes or sheets. Each depositional element exhibits a characteristic morphology and seismic response.

Although from offshore Australia, these Cretaceous-Miocene strata probably bear similarities to deep water strata in the southwestern deep water GOM (offshore Mexico). The high resolution seismic allowed placement of the architectural elements within a sequence stratigraphic framework. Falling stage systems tracts are characterized by development of small erosive channels in the upper slope, channel-levee complexes in the middle and lower slope, and sand fan lobes on the lower slope. Variations in the sediment composition are related to early development of large mass transport deposits. Lowstand systems tracts are characterized by the predominance of sand lobes on the lower slope and basin floor.

Analysis of slope gradients allowed comparison with other deep water sequences deposited on an ungraded-to-graded continuum of continental margins. The characterization of the stratigraphic grade of the margin showed the variations of the slope morphology and its consequences in the evolution of the margin from a graded margin to an out-of-grade margin.

Finally, the seismic attributes used as a guide in the seismic sequence stratigraphy interpretation were implemented in different approaches in order to build a 3D geological interpretation. The interpreted horizons were included in the implementation of a simple methodology in order to construct probability maps for improving prediction of the distribution of architectural elements within a 3D model. Furthermore, measurements and spatial distribution of the mentioned elements identified in this study are used as inputs for the object-based model approach. However, it fails honoring data when well control and even constrains are included. Improved results are observed using a Sequential Indicator simulation approach constrained by three dimensional probability volumes calculated from geobody extractions using multiple seismic attributes.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016