Geometric and depositional responses of carbonate build-ups to Miocene sea level and regional tectonics offshore northwest Australia

James Van Tuyl,Lesley Cherns,Tiago M Alves

doi:10.1016/j.marpetgeo.2018.02.034

Abstract

The geometric and depositional responses of isolated carbonate build-ups to Miocene sea-level change and regional tectonics was investigated using a combination of 3D seismic and borehole data from the Browse Basin, North West Australia, and outcrop information from the Cariatiz Reef, southeast Spain. The interpreted seismic volume documents five (5) Miocene sequence boundaries and five (5) main seismic facies. Seismic attribute analyses proved a highly effective tool for interpreting carbonate facies but, when compared with outcrop information from southeast Spain, data are limited to large-scale features of scales beyond 16.4 m vertically and 18.75 m horizontally. Hence, this work clearly shows that estimations of reservoir potential are significantly underestimated if based on seismic data alone. As a corollary of the structural analysis in this work, growth patterns suggest Messinian structural partitioning across the Browse Basin, with deformation associated with plate collision focused in preferentially orientated faults - thus only influencing carbonate build-up evolution at a local scale.

Highlights

Carbonate-hosted reservoirs are significant hydrocarbon exploration targets (Saqab and Bourget, 2015), and are estimated to comprise half of the world's hydrocarbon reserves (Ahr, 2008)
Located offshore Northwest Australia, the Browse Basin is one of a series of sedimentary basins developed on the so-called North West Shelf (Stephenson and Cadman, 1994; Rosleff-Soerensen et al, 2012, 2016) (Fig. 1)
Two major sequence boundaries include BB1, which marks the top of the Eocene-Oligocene ramp at 2789 m (1796 ms TWT) and BB5, marking the top Miocene in the Poseidon-2 well at 1808 m (1142 ms TWT)

Summary

Introduction

Carbonate-hosted reservoirs are significant hydrocarbon exploration targets (Saqab and Bourget, 2015), and are estimated to comprise half of the world's hydrocarbon reserves (Ahr, 2008). The production of hydrocarbons from such a type of reservoirs is important in equatorial regions of the Middle East (Harris and Frost, 1984; Ehrenberg et al, 2007), Indonesia (Kusumastuti et al, 2002), or the Philippines (Neuhaus et al, 2004), to provide a few examples In addition to their economic importance, carbonate sequences often record the tectonic and sedimentary evolutions of continental margins (Chang et al, 2017). The tropical Miocene sequence investigated in this work was established above a unit of temperate-water, flat-topped bryozoan reefs (Belde et al, 2017; Van Tuyl et al, 2018) Most understanding of this Miocene carbonate sequence comes from regional analyses by RosleffSoerensen et al (2012, 2016), Saqab and Bourget (2015) and Belde et al (2017).

Methods

Results

Discussion

Conclusion