Emerging Complexity of the Great Artesian Basin Aquifer Systems in the Surat

Abstract

Since the initial assessments of regional hydrodynamic flow in the Great Artesian Basin (GAB) conducted by Hitchon and Hays (1971) who applied Toth (1963) style regional analysis, the perception that the GAB is a regional hydrodynamic system of hydraulically interconnected relatively fresh water aquifers recharging across the intake beds in the north and east with discharge to the south and west, has been largely unchallenged. With the benefit of added well data, more detailed analysis of hydrodynamic systems in the search for carbon storage options with competent seals saw Hennig (2007), Hodgkinson et al. (2010), and Hodgkinson and Grigorescu (2012) begin to define more significant hydraulic discontinuity between individual aquifers and more complicated flow paths within aquifers. The recent expansion of coal seam gas development drilling and associated aquifer monitoring has provided another wave of new data that further highlights large parts of the Surat Basin (such as the Springbok and Hutton) are actually of variable chemistry and are poorly yielding aquifers that are hydraulically disconnected and geologically heterogeneous. The emerging conceptual hydrogeological model is for relatively small parts of the GAB to be hydraulically well connected. Large parts are characterised by sluggish formation water of variable ionic composition occurring with detailed complicated flow paths. This is in keeping with the geological heterogeneity expected in largely continental fluvial and lacustrine dominated depositional systems. Hennig A. 2007. Hydrodynamic interpretation of the formation pressures in CRC-1: Vertical and horizontal hydraulic communication. CO₂ CRC Reports RPT07-0626. Hitchon B. & Hays J. 1971. Hydrodynamics and hydrocarbon occurrences Surat Basin, Queensland, Australia. Water Resources Research 7, 658–676. Hodgkinson J. and Grigorescu M. 2013. Background research for selection of potential geostorage targets—case studies from the Surat Basin, Queensland, Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia, 60:1, 71–89. Hodgkinson J. Hortle A. & McKillop M. 2010. The application of hydrodynamic analysis in the assessment of regional aquifers for carbon geostorage: Preliminary results for the Surat Basin, Queensland. APPEA Conference, Brisbane. Toth J. 1963. A theoretical analysis of groundwater flow in small drainage basins. Journal of Geophysical Research. 67 (16), 4795–4812.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015