TY - JOUR

T1 - An overview of a highly versatile forward and stable inverse algorithm for airborne, ground-based and borehole electromagnetic and electric data

AU - Auken, Esben

AU - Christiansen, Anders Vest

AU - Kirkegaard, Casper

AU - Fiandaca, Gianluca

AU - Schamper, Cyril

AU - Behroozmand, Ahmad Ali

AU - Binley, Andrew

AU - Nielsen, Emil

AU - Efferso, Flemming

AU - Christensen, Niels Boie

AU - Sorensen, Kurt

AU - Foged, Nikolaj

AU - Vignoli, Giulio

PY - 2015/7/29

Y1 - 2015/7/29

N2 - We present an overview of a mature, robust and general algorithm providing a single framework for the inversion of most electromagnetic and electrical data types and instrument geometries. The implementation mainly uses a 1D earth formulation for electromagnetics and magnetic resonance sounding (MRS) responses, while the geoelectric responses are both 1D and 2D and the sheet's response models a 3D conductive sheet in a conductive host with an overburden of varying thickness and resistivity. In all cases, the focus is placed on delivering full system forward modelling across all supported types of data. Our implementation is modular, meaning that the bulk of the algorithm is independent of data type, making it easy to add support for new types. Having implemented forward response routines and file I/O for a given data type provides access to a robust and general inversion engine. This engine includes support for mixed data types, arbitrary model parameter constraints, integration of prior information and calculation of both model parameter sensitivity analysis and depth of investigation. We present a review of our implementation and methodology and show four different examples illustrating the versatility of the algorithm. The first example is a laterally constrained joint inversion (LCI) of surface time domain induced polarisation (TDIP) data and borehole TDIP data. The second example shows a spatially constrained inversion (SCI) of airborne transient electromagnetic (AEM) data. The third example is an inversion and sensitivity analysis of MRS data, where the electrical structure is constrained with AEM data. The fourth example is an inversion of AEM data, where the model is described by a 3D sheet in a layered conductive host.

AB - We present an overview of a mature, robust and general algorithm providing a single framework for the inversion of most electromagnetic and electrical data types and instrument geometries. The implementation mainly uses a 1D earth formulation for electromagnetics and magnetic resonance sounding (MRS) responses, while the geoelectric responses are both 1D and 2D and the sheet's response models a 3D conductive sheet in a conductive host with an overburden of varying thickness and resistivity. In all cases, the focus is placed on delivering full system forward modelling across all supported types of data. Our implementation is modular, meaning that the bulk of the algorithm is independent of data type, making it easy to add support for new types. Having implemented forward response routines and file I/O for a given data type provides access to a robust and general inversion engine. This engine includes support for mixed data types, arbitrary model parameter constraints, integration of prior information and calculation of both model parameter sensitivity analysis and depth of investigation. We present a review of our implementation and methodology and show four different examples illustrating the versatility of the algorithm. The first example is a laterally constrained joint inversion (LCI) of surface time domain induced polarisation (TDIP) data and borehole TDIP data. The second example shows a spatially constrained inversion (SCI) of airborne transient electromagnetic (AEM) data. The third example is an inversion and sensitivity analysis of MRS data, where the electrical structure is constrained with AEM data. The fourth example is an inversion of AEM data, where the model is described by a 3D sheet in a layered conductive host.

KW - airborne electromagnetic

KW - frequency domain electromagnetic

KW - geoelectric

KW - inversion

KW - magnetic resonance sounding

KW - transient electromagnetic

KW - LATERALLY CONSTRAINED INVERSION

KW - INDUCED POLARIZATION DATA

KW - DATA INCORPORATING TOPOGRAPHY

KW - RESISTIVITY DATA

KW - TEM DATA

KW - MAGNETIC-RESONANCE

KW - FULL-DECAY

KW - TRANSIENT

KW - TIME

KW - APPROXIMATION

U2 - 10.1071/EG13097

DO - 10.1071/EG13097

M3 - Journal article

VL - 46

SP - 223

EP - 235

JO - Exploration Geophysics

JF - Exploration Geophysics

SN - 0812-3985

IS - 3

ER -