--> Quantification and 3-D Modeling of Architectural Variability and Controls in an Eocene — Mid Miocene Carbonate Ramp, Browse Basin, Australia

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Quantification and 3-D Modeling of Architectural Variability and Controls in an Eocene — Mid Miocene Carbonate Ramp, Browse Basin, Australia

Abstract

A 287 km2 high resolution 3D seismic volume in the Browse Basin of the Australian Northwestern Shelf serves as an ideal dataset to study architectural variations and their controls in an Eocene-Mid Miocene prograding carbonate ramp system. Applying seismic stratigraphy and sequence stratigraphy to the 3D seismic volume and well log data, this study quantifies the three-dimensional variability of facies distribution, depositional geometries (geological variability) and depositional rates within the prograding carbonate clinoforms. Furthermore, the effect of sea level changes, climate, tectonics and ocean currents on facies distribution and depositional rates are delineated and quantified. Deliverables of this study are a quantified description of the 3D facies distribution, a better understanding of universal process-form relationships in carbonate systems and the role of external controls on geological variability. This makes the dataset a valuable analogue model for hydrocarbon bearing carbonate systems worldwide when it comes to estimating reservoir distribution and reservoir properties. This study presents the rates of sediment volume progradation and sediment distribution in the Browse Basin system for 13 seismic sequences from the Eocene to the Mid Miocene. The preliminary models of sediment volume geometries indicate a major influence of sea level variation with minor modification through ocean bottom currents, while the influence of climate and tectonics seems to be negligible. Sea level curves derived from dip directional cross sections throughout the seismic data indicate the intrinsic range of variability within the system itself. Ongoing work will indicate if a reasonable match between the seismically derived sea level curves and regional/eustatic reference sea level curves can be achieved. The study represents a novel approach to the subsurface-based investigation of carbonate systems by quantifying the system progradation not only as distance over time, but also as sediment volumes deposited in given time intervals. A better understanding of universal process-form relationships and the effect of external controls on facies distribution in carbonate systems furthermore enables the ability to increase the accuracy of existing carbonate reservoir models and to better predict reservoir properties in these systems.