Article

Interactive geophysical inversion using qualitative geological constraints

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Abstract

Numerical inversion of geophysical data does not normally require user interaction apart from the selection of initial inversion parameters. However, such an inversion often returns a single solution based upon default parameters. While this solution will be geophysically correct, assuming convergence of the algorithm, it may not be the most geologically reasonable answer. It is necessary to incorporate human interaction in selecting inversion solutions, this being the most efficient method for adding qualitative geological constraints. An automatic system provides a user-directed search of the space of geophysical solutions. Rankings assigned to numerical inversion results guide a genetic algorithm in advancing towards a conceptual target. Our example uses resistivity and chargeability data from a pole-dipole induced polarisation survey collected during a mineral exploration program. We invert for specific geological features: a defined, conductive top layer, sharp geological boundaries in the resistivity, and greatest depth of resolution of the inversion algorithm. The interactive system is an organised way to investigate the solution space for valid inversion results that emphasise these geological possibilities.

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... Quantifying uncertainties of 3D geological models arising from sparse geological field measurements (e.g., dip and strike measurements) has been reported before (e.g., Wellmann and Regenauer-Lieb, 2012;Lindsay et al., 2012;Jessell et al., 2014;Pakyuz-Charrier et al., 2018;Stamm et al., 2019;Giraud et al., 2017Giraud et al., , 2019Giraud et al., , 2020. Wijns et al. (2003); Wijns and Kowalczyk (2007) use interactive evolutionary computation to incorporate human evaluations of model outputs and achieve a user-directed search of the model space. However, uncertainty analysis of geological units resulting from multiple geophysical measurements has not been attempted yet. ...
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... An additional interesting path combining geophysical inversion with geological knowledge is the concept of interactive inversion (Boschetti & Moresi, 2001;Wijns, Boschetti, & Moresi, 2003;Wijns & Kowalczyk, 2007), which aims at an explicit integration of expert knowledge in the inversion process. This is achieved through a system generating possible scenarios. ...
Book
Preprint available here: https://publications.rwth-aachen.de/record/754773/files/754773.pdf
... An additional interesting path combining geophysical inversion with geological knowledge is the concept of interactive inversion (Boschetti & Moresi, 2001;Wijns, Boschetti, & Moresi, 2003;Wijns & Kowalczyk, 2007), which aims at an explicit integration of expert knowledge in the inversion process. This is achieved through a system generating possible scenarios. ...
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... An additional interesting path combining geophysical inversion with geological knowledge is the concept of interactive inversion (Boschetti & Moresi, 2001;Wijns, Boschetti, & Moresi, 2003;Wijns & Kowalczyk, 2007), which aims at an explicit integration of expert knowledge in the inversion process. This is achieved through a system generating possible scenarios. ...
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... The majority of researchers primarily focus on the prior distribution of the prestack parameters inversion (Buland and Omre, 2003;Wijns and Kowalczyk, 2007;Lelièvre et al., 2009;Karimi et al., 2010;Alemie and Sacchi, 2011). The prior distribution of the inversion parameters is only related to the vertical resolution and sparsity of the inversion results. ...
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... The scientific literature is extraordinarily rich in algorithms concerning 2D and 3D potential field data inversion (e.g., Last and Kubik, 1983;Guillen and Menchetti, 1984;Litinsky, 1989;Li and Oldenburg, 1996; Barbosa and Silva 1994;Barbosa, 2004, 2006;Cella and Fedi, 2012;Paoletti et al., 2014;Silva Dias et al., 2009;Wijns and Kowalczyk, 2007). However, there are no 1D algorithms equivalent to those applicable to seismic or electromagnetic methods. ...
Conference Paper
We present a new 1D inversion algorithm for potential field data, which consists in the inversion of vertical soundings of data at different altitudes. The inversion of multiple 1D vertical gravity/magnetic soundings is made over the same source-volume, which is a finite volume of layers of different densities, for interpreting anomalies along a profile or over a measurement surface. The inversion algorithm was tested on synthetic data and on a real case, relative to gravity data referred to a sedimentary basin in Nevada, USA.
... Clapp et al. (2004) use seismic reflector dip estimates based on migrated data to construct a nonstationary anisotropic regularization operator to be used in the objective function. Others have built on the work of Clapp et al. (2004) to allow for increased input from the interpreter to help ensure a good geologic inversion solution (Barbosa and Silva, 2006;Wijns and Kowalczyk, 2007). Guitton et al. (2012) present constrained full-waveform inversion using dip information obtained from migrated seismic sections. ...
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... Most of these aforementioned references incorporate the a priori information to the original set up of the inversion. Wijns & Kowalczyk (2007) and Barbosa & Silva (2006) develop user interactive inversion approaches, which take user input to direct the inversion towards a geologically reasonable solution. A good summary of incorporating a priori information-especially from geological data-into seismic observations can be obtained in Lelièvre (2009). ...
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... The authors also presented an adaptive learning procedure for incorporating prior knowledge (Silva & Barbosa 2006). Wijns & Kowalczyk (2007) proposed a semi-automatic procedure that allows the interpreter to set a geologically reasonable solution. With the aim of incorporating depth information and regularizing the solution, Barnes & Barraud (2012) developed an inversion algorithm that solves for the geometric interface between geological bodies. ...
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... The authors also presented an adaptive learning procedure for incorporating prior knowledge (Silva & Barbosa 2006). Wijns & Kowalczyk (2007) proposed a semi-automatic procedure that allows the interpreter to set a geologically reasonable solution. With the aim of incorporating depth information and regularizing the solution, Barnes & Barraud (2012) developed an inversion algorithm that solves for the geometric interface between geological bodies. ...
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... Another novel approach is that of Wijns & Kowalczyk (2007) who, similarly to the approach of Barbosa & Silva (2006), allow for input from the interpreter to help ensure a geologically reasonable solution. Several inversions are performed with random values for several control parameters. ...
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