Exploration Geophysics Exploration Geophysics Society
Journal of the Australian Society of Exploration Geophysicists
Table of Contents
Exploration Geophysics

Exploration Geophysics

Volume 48 Number 4 2017

We have studied the correlation between bulk mineralogy and induced polarisation (IP) responses in iron oxide-copper-gold (IOCG) and porphyry copper concealed mineralised systems in northern Chile. Data analyses show that bulk sulphide concentration is the first order factor that explains variation in the IP effect, even for the case of magnetite-related IOCG mineralisation.

EG15074Divergence correction schemes in finite difference method for 3D tensor CSAMT in axial anisotropic media

Kunpeng Wang, Handong Tan, Zhiyong Zhang, Zhiqiang Li and Meng Cao
pp. 363-373

This paper presents a study on divergence correction in the finite difference method for 3D tensor controlled-source audio-frequency magnetotellurics (CSAMT) in an axial anisotropic media. We show how divergence correction can be performed more efficiently and the study results can be used to help accelerate a whole 3D tensor CSAMT forward modelling and inversion.

The objective of this study was to overcome the limitations in using the loop-source TEM method and realise the efficient detection of mined-out areas using the short-offset grounded-wire TEM (SOTEM) method in vegetation-covered mountainous coalfields. The feasibility of SOTEM is verified by the drilling result in the field test.

Forward and inverse modelling are used to demonstrate that the resistivity method can detect alteration above the Midwest uranium deposit in Canada. The inverse section of the field data is similar to the inverse section of a synthetic model when alteration is present, but dissimilar when there is no alteration.

EG15078Near-surface high resolution imaging of a metallogenic zone in the northern fringe of Dalma volcanics in eastern India using electrical resistivity tomography

P. K. Adhikari, P. K. Yadav, Shalivahan Srivastava, Ved P. Maurya, Shailendra Singh, Anurag Tripathi, Roshan K. Singh and Ashish K. Bage
pp. 394-400

An ERT survey was conducted over a defined conducting zone through a magnetotelluric survey in the Dalma volcanics, India. The resistivity models resolved four major zones and the results corroborate well with the geological succession. The resistivity values of less than 1 Ωm at a depth of ~25 m correspond to the deposit.

EG16043Microtremor exploration for shallow S-wave velocity structure in Bandung Basin, Indonesia

Andi Muhamad Pramatadie, Hiroaki Yamanaka, Kosuke Chimoto, Afnimar, Kazuki Koketsu, Minoru Sakaue, Hiroe Miyake, I Wayan Sengara and Imam A. Sadisun
pp. 401-412

We obtained the shallow S-wave velocity profile distributions in the Bandung Basin, Indonesia, from the inversion of the observed Rayleigh wave phase velocity spectra using a microtremor survey. The profiles will be used for calculation of the average S-wave velocity of the upper 30 m and site amplification factors for seismic hazard evaluation in the area.

EG16004Adaptive mixed-norm seismic inversion for non-Gaussian errors

Zhiyong Li, Guangmin Hu and Jiashu Zhang
pp. 413-421

Subsurface-property estimation from remote geophysical measurements is subject to non-Gaussian errors. We propose to minimise the misfit with a robust error measure, which is based on a generalised Gaussian distribution. A suboptimal solution is proposed through a mixed-norm functional combination of the l1 and l2 norms.

This paper introduces a low redundancy curvelet transform which can reduce the redundancy to 10 for three dimensional data and simultaneously interpolate and denoise. Numerical experiments on synthetic and field data demonstrate that the low redundancy transform can provide reliable results while at the same time improving the computational efficiency.

EG15112Improved reservoir characterisation using fuzzy logic platform: an integrated petrophysical, seismic structural and poststack inversion study

Muhammad Kamran Jafri, Aref Lashin, El-Khedr Hassan Ibrahim, Kamal A. Hassanein, Nassir Al Arifi and Muhammad Naeem
pp. 430-448

In this study, petrophysical properties, seismic structural and poststack seismic inversion results are integrated using the fuzzy logic AND operator to characterise the Tensleep Sandstone Formation at Powder River Basin, Wyoming, USA. The 3D seismic cube and logging datasets of 17 wells are used for enhancing the seismic and petrophysical evaluation.

EG15124Effects of the symmetry axis orientation of a TI overburden on seismic images

Chih-Hsiung Chang, Young-Fo Chang and Cheng-Wei Tseng
pp. 449-455

Benefitting from the forward modelling studies, the phenomenon of spatial mispositioning in apparent reflections caused by the symmetry axis orientation of the TI overburden was demonstrated. Numerical manipulations show the imaging problems can be well described by the TERF method and properly handled by the RAKTM method.

A new parameterisation using P-wave velocity, Poisson’s ratio and density is proposed for multi-parameter full waveform inversion (FWI) for isotropic elastic media. By introducing Poisson’s ratio, the virtual source for the P-wave velocity generates additional S-waves in the partial derivative wavefields, which increases the spatial resolution of FWI.

We have developed an improved sparse apex-shifted hyperbolic Radon transform with Fourier-kernel Stolt-based modelling and imaging operators to separate seismic diffractions from reflections. The time axis is stretched to overcome the limitation of the multi-velocity model and a sparsity-promoting inversion is implemented to enhance the resolution of the Radon panel.

We have proposed a dip-oriented gradient energy entropy (DOGEE) coherence method to detect subtle faults and structural features. Theoretical synthetic datasets and a real dataset show that our proposed method is not only robust to noise, but also improves the clarity of small-scale discontinuities.

A crooked-line 2D seismic reflection dataset recorded in the northern part of the Eastern Pannonian Basin was processed to obtain a high-resolution seismic image for the area of interest. Refraction interferometry was used to enhance the first arrivals and to compute static corrections with good accuracy.

EG16098Multiple lapse time window analysis using solely single events in South Korea

Asep Nur Rachman, Tae Woong Chung and Kyung-Hoon Chung
pp. 504-511

Depth variation of scattering attenuation by applying single events to multiple lapse time window analysis (MLTWA) was recently shown; however, this application inevitably combined several events due to insufficient data. This study demonstrated that a flexible range window can be applied successfully to solely single events in MLTWA.

EG15021Radiogenic heat production in Rudeis Formation, Lower Miocene, Belayim marine oil field, Gulf of Suez, Egypt

Hassan Mohamed, Hideki Mizunaga, Nasser Mohamed Abou Ashour, Refaat Ahmed Elterb, Ibrahim Mostafa Elalfy and Ayman Shebel Elsayed
pp. 512-522

This study describes radiogenic heat production (RHP) estimated from two sets of well logging data recorded in Rudeis Formation, Belayim marine oil field. Cross-correlation of the estimated RHP (AR and ABR) yielded a moderate fit of 0.75. The three-dimensional (3D)-slicing of the reservoir shows that the northern and north-western parts of the study area have higher RHP compared to other parts.

EG16010The research on the buried public monumental complexes of Lupiae (Lecce) by geophysical prospecting

Giovanni Leucci, Lara De Giorgi, Giacomo Di Giacomo, Imma Ditaranto, Ilaria Miccoli and Giuseppe Scardozzi
pp. 523-532

This paper presents a case study that involves a geophysical survey employing the surface 3D ground penetrating radar (GPR) techniques, in order to archaeologically characterise the areas located in the south-western sector of the historical centre of Lecce (Italy). GPR measurements significantly contributed to reconstruction of the complex subsurface properties in these modern urban areas.

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