Cretaceous Stratigraphic Play Fairways and Risk Assessment in the Browse Basin: Implications for CO2 Storage and Hydrocarbon Prospectivity  

Authors / CoAuthors

Rollet, N. | Abbott, S.T. | Lech, M.E. | Caust, D. | Romeyn, R.P.

Abstract

The Browse Basin is a Paleozoic to Cenozoic depocentre, situated offshore Australia's Northwest Shelf, which contains significant hydrocarbon reserves. Some of the gas accumulations have naturally elevated levels of CO2. As part of the National CO2 Infrastructure Plan, a regional revised sequence stratigraphic analysis and new pre-competitive geophysical data acquisition (marine seepage surveys and aeromagnetic data) were undertaken to better understand the basin-wide prospectivity of the Cretaceous supersequences both for CO2 storage and hydrocarbons. Long-lived entrenched fluvial systems flowing from the Kimberley on the inner-shelf formed a complex network of sedimentary inputs that operated throughout the Cretaceous. These fluvial systems delivered numerous large Cretaceous submarine fan complexes, with variable reservoir characteristics, which were deposited in the central and northern depocentres during sea level falls in the Valanginian, Barremian, Campanian and Maastrichtian. Paleogeography, play fairways and common risk element maps have been completed to high-grade areas of interest. Risk assessments of these plays focused on containment quality and seal integrity. Simple well log analysis provided information on reservoir quality (porosity and permeability). Reactivated faults, proximity to the seal pinchouts, connectivity between sand bodies, hydrocarbon presence and indication of present-day or paleo-seepage were investigated. Geochemical analysis and Grains with Oil Inclusions (GOI) techniques were used to assess the seal integrity. Updates on current stress field and seal integrity modelling predict fault behaviour under the current stress field and which fault trends could be reactivated with CO2 injection. Further detailed studies and modelling will be required to better predict suitability and volume of potential CO2 storage in high-graded areas, which are not in direct conflict with hydrocarbon prospectivity.

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82613

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• External PublicationConference Paper

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

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2015-01-01T00:00:00

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