Bachelor of Environmental Science (Honours)
School of Earth, Atmospheric and Life Sciences
Dr Lloyd White
soper, amy, THE CHARACTERIZATION OF FRACTURE AND FLUID FLOW PROPERTIES OF THE HAWKESBURY FORMATION IN THE TAHMOOR REGION, NSW, Bachelor of Environmental Science (Honours), School of Earth, Atmospheric and Life Sciences, University of Wollongong, 2021.
Fractures and associated networks can significantly affect subsurface fluid flow. Subsurface fluid flow is of greatest significance in rocks with favourable aquifer characteristics. In this study, the Hawkesbury Formation, a natural groundwater reservoir is analysed to characterise fracture networks. Longwall mining under the Hawkesbury Formation is common in the Southern Sydney Coalfields region, NSW. Therefore, the Hawkesbury Formation is subject to altered fracture networks due to the increased stress and brittle nature of the Formation. Previous literature focuses heavily on the primary porosity and permeability of the Hawkesbury Formation with little regard for the influence fracture and associated fracture parameters have on subsurface fluid flow. This is because characterising groundwater flow in fractured rock aquifers is difficult. However, this study highlights the need to better understand how flow yields are likely to change with changes to fracture networks. Through the analysis of mechanical stratigraphy including bed thickness, parameters of fracture spacing and fracture aperture this study focuses on the calculation of fracture parameters to model and characterise reservoir flow properties. This was achieved through both observational and geophysical analysis of sedimentary core holes within a 30km radius around the Tahmoor South mine. Examining the observational fracture spacing and bed thickness of the Hawkesbury Formation was subsequently compared to the inferred bed thickness from geophysical gamma logs. The results found that both the fracture parameters and fluid flow results align with previous literature. The predicted mean fracture porosity value of 0.012% is considered insignificant, with fluid flow being predominantly matrix facilitated. The predicted average hydraulic conductivity of 0.055m/d are in close relation to the hydraulic conductivity of 0.041m/d from Tahmoor South. However, further investigation is required as the relationship between bed thickness and fracture spacing did not correlate to the hydraulic conductivity values. With refinement, this model can be used in future studies to predict reservoir flow properties and how they are likely to change if stress from longwall mining occurs.
FoR codes (2008)
040312 Structural Geology
Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.