Nuclear Magnetic Resonance is a measurement technique used in a range of fields including medical, industrial, pharmaceutical, and the energy sector. In the Oil and Gas industry it has been used since 1958 to quantify volumes of hydrocarbon and porosity. The physics of the measurement involve the use of a static magnetic field and perpendicular radiofrequency pulse to stimulate hydrogen atoms in water (or hydrocarbon) and recording their return to steady state over time. Primarily the measurement technique gives a direct, lithology independent measure of total porosity. Secondary values include information regarding pore size, specific retention, specific yield and hydraulic conductivity from the use of empirical equations. The technique has been described in great detail elsewhere (Neville & Hopper, 2017; Kleinberg, 2001). With the measurement based on magnetic fields, the Borehole Magnetic Resonance (BMR) tool can be operated in open hole, PVC and GRE cased holes without an impact on the measurement.
The purpose of this study was to demonstrate that reliable hydraulic parameters can be obtained from existing cased bores. Validation of received data was done on the East Midlands project geophysical logs by comparing data obtained from a new bore, where BMR was run in open hole versus GRE/PVC cased holes. BMR was logged in nine shallow PVC - cased holes tapping the Perth superficial aquifer. The selected bores intersect three main lithologies: Bassendean Sand, Tamala limestone and Guildford clay. Geophysical logging results were validated in two bores where CRT - pump test data were available. Evaluation and interpretation of the available data indicates this methodology can be successfully employed to discern aquifer hydraulic parameters from existing bores at an affordable cost.