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True-Amplitude Seismic Imaging Beneath Gas Clouds

Ghazali, A.R. (author)

A gas cloud is a region of gas accumulation in the subsurface, which can severely deteriorate the seismic data quality from deeper reflectors. Due to complex wave propagation through the anomaly and the resulting transmission imprint on the reflections from below this area, the image below the gas cloud is usually not properly recovered. The...

doctoral thesis 2011

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Electric characterization of construction materials through radar data inversion

Patriarca, C. (author)

The non-destructive evaluation with the aim of characterizing objects before or after treatment has taken place, and the monitoring of long-term performance is analyzed in this thesis. Generally, these test methods measure material properties or changes in these properties that decision makers are interested in. There is a variety of non...

doctoral thesis 2013

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Full wavefield migration, using internal multiples for undershooting

Davydenko, M. (author), Verschuur, D.J. (author)

Full wavefield migration (FWM) is an inversion-based imaging algorithm that utilizes the complete reflection measurements: primaries as well as all multiples, both surface and internal. Using multiples in the imaging can extend the illumination of the subsurface. In this paper we concentrate the study on the internal scattering that can be...

journal article 2013

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Multi-objective full waveform inversion in the absence of low frequencies

Bharadwaj, P. (author), Mulder, W.A. (author), Drijkoningen, G.G. (author)

Least-squares inversion of seismic reflection waveforms can reconstruct remarkably detailed models of the Earth’s subsurface. However, the cycle-skipping associated with the highfrequency waveforms are responsible for spurious local minima in its objective function. Therefore, it is often difficult for descent methods to converge to the true...

journal article 2013

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Methods for source-independent Q estimation from microseismic and crosswell perforation shot data in a layered, isotropic viscoelastic medium

Shigapov, R. (author), Kashtan, B. (author), Droujinine, A. (author), Mulder, W.A. (author)

We consider the problem of anelastic full waveform inversion in a multi-layered, isotropic viscoelastic medium from microseismic and cross-hole perforation shots. Usually, the source wavelet is not well known, so we focus on Q estimation techniques that can handle this problem. We revisit the spectral ratio method (SRM) and discuss its domain of...

journal article 2013

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The road ahead in seismic processing

Berkhout, A.J. (author)

The next generation seismic processing system will comprise a chain of unified algorithms, from preprocessing to reservoir characterization. All these algorithms are formulated in terms of a closed-loop estimation problem, showing a great similarity with each other. A critical module in each algorithm is forward modeling, allowing feedback...

journal article 2013

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Structural similarity regularization scheme for multiparameter seismic full waveform inversion

Li, M. (author), Liang, L. (author), Abubakar, A. (author), Van den Berg, P.M. (author)

We introduce a new regularization scheme for multiparameter seismic full-waveform inversion (FWI). Using this scheme, we can constrain spatial variations of parameters which are having a weak sensitivity with the one that having a good sensitivity to the measurement, assuming that these parameters have similarities in their structures. In...

journal article 2013

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Seismic Sensitivity Analysis of Different Carbonate Lithofacies: A Full-elastic Simulation

Farish, D.R. (author)

Using a complete 2D full-elastic seismic simulation from geological modelling, to 2D seismic data forward modelling, to non-linear full-waveform inversion – the interaction of various carbonate lithofacies are observed. Specifically, three different environments of deposition within a carbonate shelf along with their pore-types ranging from...

master thesis 2015

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Seismic Waveform Inversion: Bump functional, parameterization analysis and imaging ahead of a tunnel-boring machine

Bharadwaj, Pawan (author)

During a seismic experiment, mechanical waves are usually generated by various manmade sources. These waves propagate in the subsurface and are recorded at receivers. Modern seismic exploration methods analyze them to infer the mechanical properties of the subsurface; this is commonly referred as quantitative imaging. These properties assist in...

doctoral thesis 2017

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Robust estimation of VTI ( vertical symmetry axis) models via joint migration inversion: Including multiples in anisotropic parameter estimation

Verschuur, D.J. (author), Alshuhail, A.A. (author)

Since the Earth is predominately anisotropic, the anisotropy of the medium needs to be included in seismic imaging to avoid mispositioning of reflectors and unfocused images. Deriving accurate anisotropic velocities from the seismic reflection measurements is a highly nonlinear and ambiguous process. To mitigate the nonlinearity and trade-offs...

journal article 2018

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Theory for 1D full waveform inversion of surface GPR data

Slob, E.C. (author)

In one dimension, full waveform inversion is shown to be a linear problem under several conditions. I show that if the magnetic permeability can be assumed constant and electric conductivity to be zero, measuring the magnetic field at the surface or in the air suffices as input data. I present the theory using integral equations that describe...

conference paper 2018

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Full waveform inversion in a MCMC framework

Revelo Obando, Billy (author)

Full-waveform inversion within a deterministic framework commonly uses gradient-based methods to minimize a least-squares error function. Due to the non-linearity of the problem, this function has several local minima. To avoid them, it is necessary to start the optimization procedure from a good initial model. Within a probabilistic framework,...

master thesis 2018

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Ultrasound imaging of the brain using full-waveform inversion

Taskin, U. (author), Solberg Eikrem, Kjersti (author), Naevdal, Geir (author), Jakobsen, Morten (author), Verschuur, D.J. (author), van Dongen, K.W.A. (author)

Transcranial ultrasound has been used to image the brain since 1942. Currently, it is regaining interest and full-waveform inversion (FWI) methods are now employed to reconstruct speed-of-sound profiles of the brain. Many of these methods require a good starting model. Here, we test the applicability of contrast source inversion (CSI) as a...

conference paper 2020

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Full wavefield least squares reverse time migration

Davydenko, M.V. (author), Verschuur, D.J. (author)

Waveform inversion based on least-squares reverse time migration (LSRTM) usually involves Born modeling, which models the primary-only data. As a result the inversion process handles only primaries and corresponding multiple elimination pre-processing of the input data is required prior to imaging and inversion. Otherwise, multiples left in...

journal article 2021

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Moment tensor estimation through inversion of borehole microseismic data with machine learning

Revelo Obando, Eddy Darío (author)

The analysis of microseismic measurements acquired during borehole acquisition surveys is essential for a thorough understanding of the source mechanisms in hydraulic fracturing operations. Due to the injection of high-pressure fluids, induced fractures can produce seismic events of low magnitude that can be recorded and subsequently analyzed to...

master thesis 2021

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Reducing near-surface artifacts from the crossline direction by full-waveform inversion of interferometric surface waves

Liu, J. (author), Draganov, D.S. (author), Ghose, R. (author)

Seismic incoherent noise and waves scattered from objects in the crossline directions can cause 2D elastic full-waveform inversion (FWI) to produce artifacts in the resulting 2D models. We develop a complete workflow that can determine subsurface S-wave velocity (VS) models inverted from 2D near-surface seismic data more stably. We make use...

journal article 2022

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Characterizing near-surface structures at the Ostia archaeological site based on instantaneous-phase coherency inversion

Liu, J. (author), Ghose, R. (author), Draganov, D.S. (author)

Traditional least-squares full-waveform inversion (FWI) suffers from severe local minima problems in case of the presence of strongly dispersive surface waves. Additionally, recorded wavefields are often characterized by amplitude errors due to varying source coupling and incorrect 3D-to-2D geometrical-spreading correction. Thus, least...

journal article 2022

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Time Versus Frequency Domain full Waveform Inversion for Ultrasound Imaging

Ramirez, Ana B. (author), Abreo, Sergio A. (author), van Dongen, K.W.A. (author)

With full waveform inversion (FWI) all available information enclosed in the recorded wavefield - including multiple scattering, dispersion, and diffraction - is used to obtain accurate images showing quantitative information of the tissue parameters. These non-linear inversion methods are implemented either in the time or in the frequency...

conference paper 2022

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Investigating scaling techniques and the cost-efficiency of distributed to single FPGA compositions for Full Waveform Inversion

Dierick, Luc (author)

In recent years, the big data era has produced an increasing volume and complexity of data that requires processing. To analyze and process these large amounts of data, applications are being scaled on large clusters using distributed data processing frameworks. A more recent trend utilizes hardware accelerators to offload computationally...

master thesis 2022

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Full-waveform inversion of seismic data using instantaneous-phase coherency

Schaly, Jan (author)

With a rapid increase in computational resources two dimensional full-waveform inversion is evolving into a promising tool for near-surface geophysics. However, near-surface applications suffer from local minima due to amplitude errors associated with two dimensional full-waveform inversion. By clever definition of the misfit function, the...

master thesis 2022