--> Quantification of Architectural Variability and Controls in an Upper Oligocene to Lower Miocene Carbonate Ramp, Browse Basin, Australia

AAPG ACE 2018

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Quantification of Architectural Variability and Controls in an Upper Oligocene to Lower Miocene Carbonate Ramp, Browse Basin, Australia

Abstract

This study integrates seismic geomorphology and trajectory analysis of a 287 km2 high-resolution 3D seismic volume in the Upper Oligocene - Lower Miocene prograding carbonate ramp system in the Browse Basin of Australia. We delineate the effect of relative sea level changes on sediment volume distribution and lateral variability in the system, and introduce cumulative channel cross sectional area (CCCSA) as proxy for slope system stability.

Quantitative analysis of ramp evolution with focus on lateral variability yields a 3D geological subsurface model and an improved understanding of the effect of allogenic and autogenic controls on carbonate system evolution and variability. The model can serve as an analogue for hydrocarbon bearing carbonate systems worldwide to better constrain reservoir distribution and geometries, and as a tool for teaching seismic-based carbonate sequence stratigraphy. Furthermore, a better understanding of lateral variability of potential reservoir facies facilitates more informed business decisions, minimizing acquisition cost and data volume.

We present a quantitative 3D seismic analysis of ramp evolution with focus on lateral variability of sediment volume progradation in the Browse Basin system for 12 seismic sequences through the Upper Oligocene - Lower Miocene. Relative sea level changes are the main control on along-strike variability of the ramp margin by slope channel incision, which affects lateral extent and continuity of potential reservoir facies. The resulting calciturbidites form potential reservoirs and control sediment volume distribution along the slope and in the basin. We conclude that lateral variability is an underexplored aspect of the sequence stratigraphic method that can significantly affect derived relative sea level curves and subsidence rates and result in contradictory signals within a dataset.

This study presents a new way to parameterize carbonate slope channel systems and their stability, and sheds light on how basinward sediment transport is influenced by allogenic and autogenic controls. The quantitative characterization of along-strike variability of the ramp margin can help change the way we think about sequence stratigraphy in three dimensions. This opens up new, potentially unexplored predictable powers of sequence stratigraphy in field scale for characterization, development and production strategies.