Exploration Geophysics
Volume 46 Number 3 2015
EG13097An overview of a highly versatile forward and stable inverse algorithm for airborne, ground-based and borehole electromagnetic and electric data
We present an overview of a mature and general algorithm for inversion of most electromagnetic and geoelectrical data, ground-based and airborne. The implementation uses a 1D formulation for electromagnetics and MRS responses, geoelectric responses are 1D and 2D, and the 3D sheet’s response implements an overburden of varying thickness and resistivity.
EG14096mCSEM inversion for CO2 sequestration monitoring at a deep brine aquifer in a shallow sea
We developed an efficient 2.5D mCSEM inversion algorithm based on an accurate forward modelling algorithm and the judicious incorporation of a priori information into our inversion scheme. We demonstrated the successful recovery of resistivity distributions of the injected CO2 from the deep brine aquifer model in the shallow sea.
EG14016Accelerating seismic interpolation with a gradient projection method based on tight frame property of curvelet
A gradient projection method for seismic interpolation based on the tight frame property of curvelet transform is proposed. Some smooth L1 norm functions were analysed, and the Huber function was chosen to replace the L1 norm. The tight frame property of the curvelet transform is utilised to improve the computational efficiency.
The problem of estimating thin layered model parameters by amplitude variation with offset (AVO) inversion of prestack seismic data has been studied. An algorithm for solving the prestack inverse AVO problem in the case of multilayered media has been derived. Numerical examples show the accuracy and efficiency of the method.
EG14069Estimation of surface-wave phase velocity from microtremor observation using an array with a reference station
An interferometric procedure for Rayleigh wave phase velocities from cross correlations of microtremors in an array with a reference station is investigated in this study. After identifying dispersive Rayleigh waves, semblance analysis of the cross correlations was carried out to estimate phase velocities for fundamental and higher-mode Rayleigh waves.
EG13104Edge enhancement of potential field data using an enhanced tilt angle
An edge-detection technique for the enhancement of potential field data, which is based on the tilt angle of the first order vertical derivative of the total horizontal gradient, is presented. The new filter clearly enhances the edges of superimposed sources sharply and generates more subtle detail.
By assuming that anomalies in a TMI grid arise from thin magnetic layers, spectral depth estimates to one or more equivalent magnetic layers may be obtained repeatedly across large areas. A general formula is derived for the purpose and demonstrated on the TMI grid of the Northern Territory.
EG13086First application of airborne gravity to oil exploration in the Shengli oil province, eastern China
An airborne gravity survey was successfully conducted over the onshore and offshore regions of the south-west Bohai Sea. The derived Bouguer gravity data and inversed results correlate well with features such as known faults, swells, sags, and oilfields identified by earlier seismic survey and drilling data.