Determining petrophysical and hydrogeological parameters from historical bore logs for the Leederville-Parmelia aquifer, northern Perth Basin, using regression methods

Abstract

A new workflow of bore data re-interpretation that increases the value of old data with only a minimal cost has been developed. The workflow estimates hydraulic and petrophysical parameters from historical bore data, providing clay volume, total porosity, effective porosity or free fluid, permeability, hydraulic conductivity and salinity profiling. Hydraulic parameters were calculated for bores installed in the Leederville-Parmelia aquifer in the northern Perth Basin during 2018 and 2019 by using natural gamma ray, resistivity and borehole magnetic resonance logs. The bores were sampled and the laboratory analysis of water salinity was used to verify the accuracy of the computations. Using a regression analysis to correlate the “old with the new”, estimates for these parameters were then calculated for older bores that only had natural gamma logs, resistivity logs and geological logging details available. The calculated salinity values from the historical bores were validated using existing chemistry sampling. This workflow facilitates the calculation of hydraulic parameters across a regional area and potentially reduces the timing and resourcing of investigation programs by increasing the information available from historical bore data.