Geochemical characterisation and provenance analysis of conventional Late Jurassic reservoirs, Dampier Sub-basin, Northern Carnarvon Basin, Western Australia

Declan James Bonnick

Research output: ThesisMaster's Thesis

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Abstract

Geochemical characterisation of Late Jurassic sediments was conducted to distinguish provenance and dispersal through deep-water systems in the Dampier Sub-basin. In spite of the economic importance of the Angel Formation, few studies have focussed on the provenance and distribution of reservoir sandstones in the basin. Geochemical data was obtained using portable-XRF analysis on both cuttings and core samples from three wells along a transect of the basin. Comparison of geochemical data with core textures, fabric, structures and composition, as well as graphical and statistical analysis of data, was used to interpret element-element and element-mineral relationships. These relationships were used to characterise the sedimentary successions of each well into chemozones of similar geochemical composition. A comparison of geochemical data of equivalent biostratigraphic age in wells allowed the interpretation of sediment supply and dispersal throughout the Dampier Sub-basin during the Late Jurassic. Transverse sediment supply from basin margins dominated the Oxfordian and Kimmeridgian based on contrasting geochemical signatures of sandstones of the Eliassen Formation in wells proximal to the basin margins and a predominance of mudstone deposition in the central part of the Dampier Sub-basin. A significant axial supply of increasingly sand-rich sediment commencing in the early Tithonian from the northeastern Dampier Sub-basin resulted in widespread Angel sandstone deposition towards the southwest through basin-floor fans. The wells along the flanks of the sub-basin showed contrasting geochemical signatures, this time with different signatures to the central part of the basin, signifying a continuation of transverse sediment input during the Tithonian, causing a mixed geochemical signature.

This study presents new insights into sediment supply and dispersal of Eliassen Formation and Angel Formation reservoir facies in the Dampier Sub-basin. These insights are important for future exploration targeting in the basin and provide a qualitative analysis of reservoir quality in the Late Jurassic sandstones. Additionally, the major axial sediment supply in the Tithonian highlights a dominantly northeast sediment source with transport to the south, in contrast to the large-scale south to north sediment transport routes that dominated the Northern Carnarvon Basin during the Triassic and Early Cretaceous.
Original languageEnglish
QualificationMasters
Awarding Institution
  • The University of Western Australia
Award date8 Feb 2017
Publication statusUnpublished - 2016

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