This paper presents a 21-point finite difference (FD) scheme for the frequency-space domain elastic wave forward modelling, which is about 15% lower in memory consumption and computing time than the 25-point scheme. The numerical examples show that the 21-point FD scheme is valid in the sense of the numerical simulation of ideal models.

A new method is proposed to convert gamma-ray log data to in situ uranium estimates, which is especially applicable to high grades (>2 %). Monte Carlo modelling is utilised to derive the necessary environment corrections, which is demonstrated on log data from two deposits and a variety of probes.

This paper presents 34 new heat flow estimates from the western Otway Basin. The average estimated heat flow is 65.6 mW/m², with a range of 42–90 mW/m². Some areas have heat flow that is slightly anomalous, coinciding with dormant Pleistocene-Holocene volcanoes, but the simplest explanation comes from heterogeneous basement heat production.

This paper presents a fast magnetotelluric inversion algorithm which is distinctive for the level of accuracy it attains while bypassing the sensitivity matrix update. It updates the smoothness filter coefficients at each model element. Using synthetic examples, we demonstrate that the method can bypass the sensitivity matrix update.

New methods of analysis of magnetic gradient tensor data have been applied to analyse the magnetic signature of the Early Permian Mount Leyshon gold-mineralised system in Queensland.

High resolution airborne geophysical data were acquired by Fugro Airborne’s GEOTEM system over the Mohar Cauldron Complex (MCC). Advanced processing and interpretation mapped the major geological domains and indicated the presence of three felsic intrusive bodies. The boundary of the sediments within the MCC and subsurface distribution of conductivities are accurately mapped.

This paper proposes a systematic methodology to measure the reliability of seismic inversions through prior seismic-to-well correlation analyses for the fidelity of seismic data. Case studies from several oilfields show the potential application of the methodology in reducing the uncertainty of seismic inversions in the characterisation of complex reservoirs.

In order to improve imaging accuracy, we have developed an acoustic prestack reverse-time migration (RTM) scheme based on the time-space domain high-order staggered-grid finite-difference method. Additionally, we apply adaptive variable-length spatial operators to compute spatial derivatives to decrease computational costs effectively in RTM.

Reflectivity series of seismic traces are developed in a random-search scheme by using adaptive simulated annealing as a tool for sparse spiking deconvolution. Then, P-wave velocities are estimated by considering Gardner’s equation for density and velocity. Results of processing Marmousi data using this random layer-stripping algorithm are presented.

In this paper, two improved theta map filters are presented, which use the power transform and the exponential transform of the theta map to recognise the edges of the sources. The advantage of the new filters lies in their ability to delineate the source edges more clearly.

A helicopter time-domain EM (HTEM) system was flown along the Coorong which contains very shallow waters ranging from saline to extremely hypersaline. Interpretation of data via 1D inversion shows that HTEM has the potential to detect shallow water depths and conductivity gradients to monitor hypersalinisation in ecologically important wetland areas.

Lineament analysis is implemented for quantifying levelling in an aeromagnetic dataset. A lineament’s azimuth separates geologic sources from artefacts associated with acquisition or pre-processing. Lineaments are displayed as rose diagrams and the numerical difference along specific azimuths before and after pre-processing quantifies the suppression of flight-line variations.