Petrology, Diagenesis and Reservoir Quality in the Hawkesbury Sandstone, Southern Sydney Basin, AustraliaAl Gahtani F*
Ministry of Energy and Industry and Mineral Resources, Riyadh, Saudi Arabia
- *Corresponding Author:
- Al Gahtani F
Ministry of Energy and Industry and Mineral Resources
Riyadh, Saudi Arabia
E-mail: [email protected]
Received date: January 05, 2017; Accepted date: February 28, 2017; Published date: March 8, 2017
Citation: Al Gahtani F (2017) Petrology, Diagenesis and Reservoir Quality in the Hawkesbury Sandstone, Southern Sydney Basin, Australia. J Geol Geophys 6:283. doi: 10.4172/2381-8719.1000283
Copyright: © 2016 Al Gahtani F. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Petrography of the Hawkesbury Sandstone was described by thin section, scanning electron microscope and Xray diffraction techniques. Quartz is dominant in the Hawkesbury Sandstone which contains very minor feldspar, lithic grains, mica and heavy minerals. The Hawkesbury Sandstone is quartzarenite to sublitharenite. Quartz includes monocrystalline and polycrystalline grains while the feldspar includes both K-feldspar and plagioclase. Volcanic, sedimentary and chert rock fragments are present. Thin section porosity occurs in the Hawkesbury Sandstone, particularly the coarse-grained deposits. Primary porosity is more common than secondary porosity in the Hawkesbury Sandstone. Thin sections and scanning electron microscopy were used to describe diagenetic alterations and their influence on porosity in Hawkesbury Sandstone. These diagenetic alterations include compaction, quartz overgrowths, authigenicclay minerals and carbonate cement. Compaction occurred in the Hawkesbury Sandstoneduring throughout diagenesis. The influence of chemical compaction on thin section porosity was greater in the Hawkesbury Sandstone. Quartz overgrowths are common in the Hawkesbury Sandstone where they have a strong influence on porosity. Authigenic clay minerals are the widespread in the Hawkesbury Sandstone filling pores and occurring as grain-coatings on detrital and authigenic grains. Where they coat quartz grains they preserve porosity by preventing growth of quartz overgrowths. Pore-filling carbonate cement reduced porosity whereas dissolution of carbonate resulted in secondary porosity. Dissolution of unstable feldspar and lithic grains is absent in the Hawkesbury Sandstone. The Hawkesbury Sandstone is characterized by primary and secondary porosity, thus it has good groundwater storage and flow potential. Medium- and coarse-grained sandstone beds are common in the Hawkesbury Sandstone but it shows vertical variations in porosity. A few impermeable shale and siltstone units occur in the Hawkesbury Sandstone forming local confining layers.