As such it has been the object of a plethora of studies [e. Notice that this sense of shear, associated with contractional tectonics across the Apennines [ Billi et al. In the wake of the evidence supplied by these earthquakes, Fracassi and Valensise  reinterpreted the seismotectonics of the earthquake sequence, possibly the largest in Italian history, suggesting to extend the buried MGsz further to the west toward the core of the Apennines see section 3. This sector of the northern African margin is bounded to the east by the Malta Escarpment Figure 1 , an inherited Mesozoic tectonic boundary separating the continental crust of the Pelagian block from the oceanic crust of the Ionian basin [ Scandone et al.
Similarly to what is observed in the Adriatic foreland see section 2. Grasso et al. The Mesozoic to Quaternary overburden consists mainly of interlayered volcanic and marine sedimentary successions with a total thickness in excess of 5 km [ Jongsma et al. On the basis of offset drainage patterns, Catalano et al. This offset was attained between 1. These latter two points will be thoroughly discussed in sections 3. To the east, it is bounded by the Malta Escarpment, which marks the progressive transition from continental to oceanic crust in the Ionian Sea [ Catalano et al.
In contrast, their sense of motion has been variously interpreted e. On the basis of evidence of synsedimentary activity, these faults are assumed to have operated since the Miocene. Available seismic reflection lines allow the Scicli offshore to be mapped for a minimum length of 40 km [ Grasso et al. They were both complex events generated by the rupture of adjacent or nearby fault segments, and caused widespread destruction and significant effects on the environment Guidoboni et al. The Gargano earthquake was followed on the same day by a M w 5. The Sicily earthquake was felt all over eastern Sicily and was preceded by a strong foreshock on 9 January M w 6.
The seismic sequence lasted until Most likely the main shock itself included two or more subevents, as suggested by the existence of two separate concentrations of damage, but this hypothesis is not explicitly backed by the available historical sources. Such a source, however, would explain the occurrence of the tsunami but not the observed damage pattern, since the largest shaking took place inland, 10—20 km from the coastline and south of the Lesina Lake Figure 2.
Most of the proposed sources for the Gargano earthquake are instead onshore [ Salvi et al. Also in this case the main open question regards the mismatch between the hypothesized offshore source and the damage pattern, which displays the highest intensities inland Guidoboni et al. We remark that, similarly to the case of , only an inland source is compatible with the observed intensity distribution.
An offshore source 1 would not explain the observed intensity decay along the coast and 2 would require an unrealistically high seismic moment to account for the very large intensities X and XI reported over 50 km west of the Ionian coast. Sirovich and Pettenati  proposed a NNE oriented, 60 km long fault nearly overlapping the VSsz and characterized by oblique motion.
At the opposite end of the spectrum, Gutscher et al. Lavecchia et al. In the Gargano, historical seismicity concentrates near the eastern and northern coasts, testifying to the activity of the Mattinata Fault and of other still unknown structures Figure 2. Sizable earthquakes occurred on 31 May M w 6. The historical seismicity of the Hyblean foreland is much more significant Figure 3 and includes several destructive earthquakes, some followed by a tsunami [ Tinti et al. Among them, the 3 October , M w 5. Castello et al. Milano et al. The 31 October to 1 November Molise earthquake sequence shed light on the potential of the westernmost reach of the MGsz Figure 2.
Two similarly large M w 5. Similarly to the Gargano area, seismicity extends down to the depth of the Moho, about 30 km, and concentrates in the 15—25 km depth interval.
The 13 December , M L 5. In map view this earthquake falls on or just to the west of the Malta Escarpment, but its depth 22 km indicates that it occurred well below the rather shallow NE dipping normal faults that delineate the submarine scarp. No breakout data are available for the Adriatic foreland near the Gargano Promontory Figure 2 , but to the south, within the same foreland, the stress map of Italy [ Montone et al. Finally, Barba et al. At the scale of the country, studies using GPS velocities from campaigns [ Hollenstein et al.
Ferranti et al. For instance, Giuliani et al. The Mattinata Fault has also been interpreted as the source of sizable historical earthquakes e. Chilovi et al. The 15 km estimate, however, was originally proposed by De'Dominicis and Mazzoldi [ ] as a cumulative value for the entire slip history of the Gondola Fault Zone.
On the basis of analog modeling, Di Bucci et al. Tondi et al. Unfortunately, the state of activity of the Scicli offshore is not backed by background seismicity data Castello et al. This system can be subdivided into three main segments: the Cava d'Aliga, Ragusa, and Giarratana faults, from south to north, respectively [ Catalano et al.
Nevertheless, a swarm of historical and instrumental earthquakes up to magnitude 5. Whether and how the VSsz continues across this area is unknown: no data are available to even speculate on this issue. In detail, both shear zones display two fault systems in the foreland, the first of which is submerged Gondola Fault Zone and Scicli offshore, respectively whereas the second one is exposed in the mainland Mattinata Fault and Scicli onshore, respectively. A third fault system is located near the front of the chain, buried below the foredeep deposits or covered by pillow lavas Chieuti High and Vizzini Fault Zone, respectively.
The MGsz also exhibits a fourth fault system buried below the frontal part of the Apennines wedge. The most recent slip reversal of the MGsz has been interpreted as related to the contemporaneous deactivation of the southern Apennines frontal thrust ramp [ Di Bucci et al. In Sicily, the frontal thrust ramp of the Gela nappe in correspondence with the VSsz ceased its motion roughly at the same time [ Patacca and Scandone , b ].
Therefore, we hypothesize a similar reason also for the slip reversal along the VSsz. Notice that the frontal thrust deactivation must not necessarily correspond to the end of the contraction in the whole chain, as it depends on the critical taper of the wedge front. In the absence of this integration, the sense of shear and even the mere state of activity or quiescence of both the MGsz and VSsz would still be debated.
Some of these earthquakes Tables 1a and 1b have been positively associated with the fault systems comprising the investigated shear zones Figure 4. The complexity of the largest earthquakes and the moderate magnitude of the smaller ones see section 3. Timofey Eltsov and Tadeusz W. Preview Abstract We present a technique for the detection of integrity of the magnetic cement behind resistive fiberglass casing.
Numerical simulations show that an optimized induction logging tool allows one to detect small changes in the magnetic permeability of cement Missing well-log data prediction using Bayesian approach in the relative-geologic time domain. Preview Abstract We propose a method to estimate missing sonic logs using Bayesian estimation in the relative geologic time domain. In this approach, we first use local similarity to estimate alignment shifts to stratigraphically correlate several well logs to the Identification and characterization of natural fractures in gas shale reservoir using conventional and specialized logging tools.
Preview Abstract For the quantification of fractures in shale, several methods have been proposed from laboratory data and well logs analysis. However, challenges are still remained for the identification and characterization of natural fractures in shale reservoir. Triaxial induction tool response in dipping and triaxially anisotropic formations. Preview Abstract Over the years, triaxial induction tools have found applications in not only determining resistivity anisotropy and dip of formations, but also in detecting fractures.
When fractures are developed in a formation, the formation can exhibit triaxially Porosity prediction and application with multiwell-logging curves based on deep neural network. Preview Abstract Accurate calculation of reservoir porosity is the key to geological interpretation and petroleum exploration decision. Porosity is influenced by various geological factors such as buried depth, tectonic position, sedimentary environment, lithologic change Using geophysical well logs to evaluate the mechanical parameters of a turbiditic reservoir in Campos Basin, southeast Brazil.
Lais Monteiro and Abel Carrasquilla. Preview Abstract The field of the geomechanical properties of the rocks is a very significant work in oil field operations, such as reservoir characterization, drilling, completion and production monitoring. For such reason, this study focuses on deriving these parameters Automatic detection of reflectors and their local dips from borehole acoustic array data.
Anna Przebindowska and Tim Geerits. Preview Abstract Modern borehole acoustic array data can provide high-resolution, sub-seismic scale images of geological features up to about hundred feet away from the borehole. However, interpretation and automatic feature extraction from these images is rather Simulation study of simultaneous anisotropy inversion method.
Preview Abstract The simultaneous inversion method for obtaining formation shear-wave anisotropy parameters is widely used based on the four-component dipole acoustic data. The method combines the information of the fast and slow principal waves and the auxiliary waves Wellbore integrity investigation using seismic tube-wave and time-domain reflectometry: Laboratory modeling.
Preview Abstract Integrity of boreholes is key to subsurface resource extraction, energy storage, and waste disposal. Monitoring the integrity of a well is challenging due to the inaccessibility, high cost, and the complex of the subsurface condition. In this study, we An imaging method utilizing PGNAA gadolinium prompt gamma to determine propped fracture parameters and its application.
Preview Abstract The ability of induced fractures to improve well production is dependent upon three primary characteristics of the fracture geometry: fracture height, fracture width, and fracture length. These methods containing micro-semic, acoustic, temperture logging Transdimensional Bayesian inversion for directional resistivity logging while drilling data. Preview Abstract Real-time geosteering technology plays a key role in horizontal well development, which keeps the wellbore trajectories within target zones to maximize reservoir contact.
Deep-directional-resistivity logging while drilling LWD tools have longer Detection of conductive fluids associated with hydraulic fracturing using surface based CSEM: Steel casing effects. Matthew Couchman and Mark E. Here we explore the capability of controlled source electromagnetic CSEM methods to detect Casing-integrity mapping using top-casing electrodes and surface based EM fields. Preview Abstract Among the most serious issues facing the oil and gas industry is the condition of older wells.
In the US alone more than 1 million wells have mechanical or corrosive degradation of the well completion, resulting in mechanical instability and potential Monitoring hydraulic-fracture volume using surface-to-borehole EM and conductive proppant. Michael Hoversten and Christoph Schwarzbach. Preview Abstract Numerical forward and inverse simulations using measured electric and magnetic field noise spectra and actual deviated well casing geometries are performed.
The simulations demonstrate that hydraulic fracturing using typical slurry volumes of electrically Daniele Colombo and Gary W. Preview Abstract A baseline surface-to-borehole CSEM survey was performed in a supergiant oil field in Saudi Arabia with the objective of monitoring the evolution of the waterfront around a vertical monitoring well. Several aspects were taken into consideration including Effects of completion design on electrically stimulated casing and its 3D response.
Chester J. Weiss , Evan Um , and Michael Wilt. Preview Abstract To better understand the factors contributing to electromagentic EM observables in developed field sites, we examine in detail through finite element analysis the specific effects of casing completion design. The presense of steel casing has long been Gary W. McNeice and Daniele Colombo. Preview Abstract A surface-to-borehole controlled source electromagnetic CSEM survey was acquired in a research well in the eastern province of Saudi Arabia to monitor waterfront movement in a supergiant oil field.
The initial baseline CSEM survey was conducted in a Top-casing electric-source method for imaging hydraulically active fracture zones. Preview Abstract We examine the detection and imaging sensitivity of surface electric field measurements over a 3D hydraulically active fracture zone HAFZ at depth when one end point of a surface electric dipole source is directly connected to a wellhead.khjfdgjhfg.co.vu/10656.php
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Improved upscaling of steel-cased wells through inversion. Christoph Schwarzbach and Eldad Haber. Preview Abstract Accurately simulating electromagnetic fields for oil reservoirs where conductive casings are present requires special care when building parameter models. Because casings and geological structures present in the reservoir occur at significantly different EM 2 — Theory August Data-driven initial-model estimation with application to marine CSEM data. Rune Mittet and Lodve Berre.
Preview Abstract Initial model estimation can be fully data driven. Normally only one inversion run is required to achieve a good estimate for a smooth initial model with this approach. The scheme saves the operator in charge of the processing from repeated tests to find Time evolution of the electric field: Part 1 — Using the rapid expansion method REM with pseudospectral evaluation of spatial derivatives. Paul L. Stoffa and Anton Ziolkowski. Preview Abstract We present a method for modeling transient EM data acquired on land or at sea.
We use the rapid expansion method REM to develop the 3-component electric wave field time response from the spatial responses found using a pseudo-spectral method. Robust optimal synthetic aperture imaging of towed streamer electromagnetic data. Xiaolei TU and Michael S. Preview Abstract The synthetic aperture SA method has recently found applications in analysis of the low frequency marine controlled source electromagnetic data. It has been shown in numbers of publications that SA method can enhance the response from an anomalous Practical methods for model uncertainty quantification in electromagnetic inverse problems.
Randall L. Mackie , Federico Miorelli , and Max A. Preview Abstract Geophysical inverse problems are non-unique. Through regularization and the use of a priori information we can derive stable and geologically reasonable inversion models. Providing an analysis of the model uncertainty is necessary for the critical task of Guided fuzzy c-means clustering inversion of electrical potential due to an anisotropic-layered half-space. Joseph Capriotti and Yaoguo Li. Preview Abstract Most geophysical properties have a directional dependence, or anisotropy, that affects our measurements. However, this is still not commonly taken into account in inversions.
Here we develop a clustering inversion method for a layered anisotropic Preview Abstract The grounded electric source airborne time-domain electromagnetic GREATEM method has recently undergone a number of advances, including development of tools that can produce large source moments and hence allow for large transmitter—receiver offsets and Location-based parameterization of CSEM data inversion for the monitoring of hydraulic fracturing with magnetically enhanced proppants.
Preview Abstract We developed a particle mapping PM method which optimizes the location of each particle using a priori information on the susceptibility-volume product as a constraint. This PM method was applied to the imaging of magnetically enhanced proppants for Jones , Alan D. Chave , Shane F. Evans , and Jessica Spratt.
Such systems allow more rapid acquisition compared to standard magnetotelluric MT approaches. Instead of EM 3 — Applications August Daniil V. Shantsev , Elias A. Nerland , Amir Babakhani , and Leiv J. Preview Abstract Repeatability of acquisition parameters for the base and monitor surveys is an important consideration for time-lapse studies of hydrocarbon reservoirs using controlled-source electromagnetics CSEM. Variations in parameters such as source and receivers Identification of geothermal reservoirs from ensemble-based Bayesian inversion of 3D MT data. Svenn Tveit and Trond Mannseth.
Preview Abstract We consider the problem of identifying geothermal reservoirs in an exploration setting utilizing information from transient electromagnetic TEM and magnetotelluric MT data. The inversion methodology proposed uses information about the conductive clay Magnetotelluric imaging for exploration in fold-and-thrust belt settings: A feasibility and case study. Rita Streich and Akshat Abhishek.
Preview Abstract We investigate the potential of magnetotelluric MT imaging to aid exploration activities in fold-and-thrust belt settings. While MT is known to be sensitive to electrically conductive structures, here we examine resolution capabilities for strongly MT modeling and inversions for the Bolivian foothill exploration, from unconstrained to constrained, from 2D to 3D.
Jorlivan L. Correa and Paulo T. In the present article, we report the 3D CSEM finite—difference time domain forward study to generate Marine self-potential and controlled-source EM measurements using an autonomous underwater vehicle. Preview Abstract Using an autonomous underwater vehicle AUV equipped with a three-axis electric field receiver we were able to make measurements of self potential SP fields over a hydrothermal prospect in the Iheya area of the Okinawa Trough, southwest of Japan. Electromagnetic mapping of offshore groundwater on the US Atlantic continental shelf.
Preview Abstract Submarine groundwater contained in continental shelves may be a significant global phenomenon, yet little is known about its distribution. Off the US Atlantic coast, boreholes have revealed low salinity groundwater far offshore but are unable to EM P1 — Developments August On tilted transmitters in time-domain electromagnetics.
Andrei Swidinsky. Preview Abstract The response of an inclined time domain electromagnetic TEM system over a layered earth is derived and studied both in the marine and land environments. On land, only horizontal current flow can be induced in a layered subsurface, regardless of Electromagnetic modeling of induced polarization with the fictitious wave-domain method.
Rune Mittet. Preview Abstract The fictitious wave domain method makes a numerically effective implementation of finite-difference simulations of lowfrequency electromagnetic field propagation in the earth feasible. Up until now frequency dependent conductivity has not been considered Meshless inversion of magnetotelluric data. Preview Abstract We present a novel two-dimensional inversion scheme, which uses a meshless approximation framework to recover Earth models from available magnetotelluric data.
Given the theoretic description of the forward modelling scheme, we provide an extension to a Study on the performances of optimization methods of particle swarm and eigenstate analysis in CSEM data synthetic aperture processing. Preview Abstract After Fan introduced the concept of synthetic aperture SA to marine controlled-source electromagnetics CSEM , numerous of optimization methods are applied to SA weights selection for improving the detectability of deeply buried targets under seabed, Preview Abstract We carry out the inversion of marine controlled-source electromagnetic data using real coded genetic algorithm to estimate the isotropic resistivity.
Unlike linearized inversion methods, genetic algorithms belonging to class of stochastic methods are not Divergence of tipper real induction vector in tensor frequency-domain ground-airborne electromagnetic method. Preview Abstract Frequency-domain ground-airborne electromagnetic method has the potential and advantages of rapid detection in largearea with a deep investigation depth.
However, due to the limitations of source excitation method, data processing and interpretation Three-dimensional electromagnetic forward-modelling using gauge potential technique. Musa A. Bello , Jianxin Liu , and Rong-wen Guo. To unravel the Using multiphase fluid-flow modeling and time-lapse electromagnetics to improve 4D monitoring of CO2 in an EOR reservoir. Kris MacLennan and Christine Doughty.
Cretaceous Ostracoda from wells in the southeastern United States :: State Publications II
Preview Abstract Understanding the changes in the saturation within a reservoir undergoing enhanced oil recovery EOR is crucial to optimizing production. We debut a novel, multiphase fluid flow modelling code, TOGA, to assist in modeling gas, oil, and water phases Understanding and overcoming risks of CSEM for reservoir monitoring. Preview Abstract A new technology for reservoir monitoring includes full field controlled-source electromagnetics CSEM and microseismics. To mitigate the risk, we have developed full technology cycle: from patents, hardware, acquisition methodology, to data processing Preview Abstract In this paper, we propose a 3D regularized inversion method for frequency-domain marine controlled-source electromagnetic CSEM data.
In this method, the model is discretized by unstructured tetrahedral grids, which is suitable for simulating complex We applied this inversion on three survey lines from the given data set to image the salt body and The galvanic HeliSAM survey uses a large grounded electric dipole and a mobile cesium vapor magnetometer to simultaneously yield magnetic, magnetometric Analysis of simultaneous velocity and source parameter updates in microseismic FWI.
Nadine Igonin and Kristopher A. Preview Abstract In the microseismic field, a complete characterization of events involves determining the positioning and focal mechanism properties, which requires an accurate seismic velocity model. Conversely, the construction of a velocity model with surface seismic Multiscale direct-envelope inversion using wavenumber filtering based on reflection tomography for background velocity recovery of large-scale, strong-contrast media. Regularized full-waveform inversion for salt bodies. Preview Abstract Full-waveform inversion FWI aims to resolve an ill-posed non-linear optimization problem in order to retrieve unknown subsurface model parameters with high resolution from seismic data.
The non-linearity, in the absence of low frequencies from the Adaptive preconditioning of full-waveform inversion based on structure-oriented smoothing filter. Donguk Lee and Sukjoon Pyun. Preview Abstract In seismic full waveform inversion, regularization or preconditioning have been exploited to stabilize the inverse problem. Isotropic smoothing is one of the easiest way to implement regularization in full waveform inversion.
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However, the isotropic Joint-acoustic full-waveform and gravimetric inversion. Silva , J. De Basabe , M. Sen , M. Here we employ joint inversion of gravity and full waveform seismic data for estimating shapes and locations of salt bodies. Multiscale time-frequency domain full-waveform inversion with a local correlation-phase misfit function. Preview Abstract To mitigate the cycle skipping of Full Waveform Inversion FWI , we introduce a correlation-phase misfit function in the time-frequency domain, which is defined as the correlation between the phases of synthetic data and recorded data.
The correlation Full-waveform inversion based on gradient-sampling algorithm with randomized space shift. Preview Abstract Full waveform inversion FWI has the great potential to retrieve high fidelity subsurface models, with the constraint that the traveltime difference between the predicted data and the observed data should be less than half of the period at the lowest Waveform-based source-parameter estimation for elastic full-waveform inversion. Preview Abstract Estimating source parameters e.
Waveformbased source-parameter estimation potentially leads deeper insights into the nature of Elastic full-waveform inversion of multicomponent ocean-bottom data in the Moere Vest Basin, offshore Norway. Gustavo Alves and Biondo Biondi. Preview Abstract The extension of full waveform inversion FWI into elastic models can potentially address the limitations of acoustic FWI due to amplitude versus offset effects.
We present results of applying an elastic FWI workflow to multicomponent ocean-bottom nodes FWI on land seismic datasets with topography variations: Do we still need to pick first arrivals? Preview Abstract Building accurate depth migrated seismic images in on-shore environments is very challenging, especially for data acquired in areas of strong topography changes and complex shallow velocities variations like in foothills context. The examples presented in The survey was conducted simultaneously with a conventional ocean-bottom node OBN survey that used dual airgun Preview Abstract Reservoir imaging under the triangular Conger salt remains very challenging even after significant velocity model building efforts in recent years.
Continuity and focusing of reservoir reflectors are sub-optimal due to subtle velocity errors from the Preview Abstract Performing 3D time-domain full-waveform inversion FWI poses a challenge in terms of computational resources required, especially when the volume of recorded data is large. We adopt a subsampling strategy, wherein only a fraction of the total data are High-resolution full-waveform inversion for structural imaging in exploration. Preview Abstract We demonstrate a recent application of high resolution Full-waveform inversion in the exploration setting.
Supported by quality Ocean-bottom node data, we used successive higher frequency data up to imaging frequencies in the FWI workflow. The resulting Preview Abstract We recently acquired a full-azimuth, long-offset, high density ocean-bottom-node OBN dataset in Trinidad, and early analysis of the data seemed to suggest large effects of azimuthal anisotropy in the subsurface. It is well-known that significant image Preview Abstract Deriving an accurate subsurface velocity model in complex geology requires seismic data with long offsets and wide signal bandwidth in combination with high-resolution model building and imaging methods.
Full waveform inversion FWI has become a powerful A model reduction approach for full-waveform inversion via generalized multiscale finite elements. Yongchae Cho , Richard L. Preview Abstract We applied a model reduction technique known as the generalized multiscale finite element method GMsFEM to accelerate full-waveform inversion.
GMsFEM combines results of calculations on two different sizes of grids the fine and coarse grids. The fine Efficient frequency-domain reflection-based full-waveform inversion using wavefield separation. Hyunggu Jun. Preview Abstract Full waveform inversion FWI is a suitable algorithm to invert the subsurface velocity with high accuracy. The low frequency components and long offset seismic data are necessary for the FWI to invert the long wavelength velocity. To invert the long Addressing the challenges of heritage surface seismic data in a complex shallow water environment for improved overburden imaging and reservoir characterization.
Preview Abstract We present an integrated workflow that involves broadband reprocessing, high-resolution model building, and depth domain inversion, aiming to reduce some of the uncertainties of the Cook reservoir, located in the West Central Graben of the North Sea. Essential steps for successful full-waveform inversion using land data. Preview Abstract While low-frequency seismic data are crucial for the success of full-waveform inversion FWI to overcome sensitivity to starting velocity fields, this part of the data suffers the most from low signal-to-noise ratio SNR , especially for land Mitigating amplitude versus ray-parameter effect in joint migration inversion using a zero-lag crosscorrelation objective function of redatumed wavefields.
Preview Abstract Joint migration inversion JMI is a recently proposed full wavefield inversion method, which tries to minimize the mismatch between observed reflection data and forward modeled data, which is based on decoupled velocity and reflectivity models. A demigration-based reflection full-waveform inversion workflow. Preview Abstract Reflection FWI is effective at providing low-wavenumber velocity updates for deep areas beyond the penetration depth of diving waves and significantly improves seismic imaging.
However, the tomographic term of the FWI gradient that is good for low Correcting for salt misinterpretation with full-waveform inversion. Preview Abstract Using full-waveform inversion FWI to update velocity models that contain salt bodies with high velocity contrasts is challenging. It is even harder if erroneous salt geometry is part of the velocity model. Shen et al. A subsampled truncated Newton approach for multiparameter full-waveform inversion. Gian Matharu and Mauricio D.
Preview Abstract Accounting for the Hessian in full waveform inversion can lead to higher convergence rates, improved resolution, and better mitigation of parameter trade-offs in the multi-parameter case. In spite of these potential advantages, the widespread adoption of Multiscale full-waveform inversion using flux-corrected transport.
Mahesh Kalita and Tariq Alkhalifah.
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Preview Abstract Full-waveform inversion FWI iteratively recovers the unknown model parameters from seismic data. In practice, a successful FWI implementation often follows a multistage recovery approach: starting from the retrieval of the lower model wavenumbers A graph-space approach to optimal transport for full-waveform inversion. Allain , R. Brossier , Q. Oudet , and J. Preview Abstract Optimal transport distances have been recently proposed to design more convex misfit functions in the frame of full waveform inversion.
The main difficulty for this strategy is the non-positivity of seismic data: the optimal transport is developed for the Overcoming cycle skipping in full-waveform inversion by reducing the adjoint sources oscillations. Preview Abstract Classical full waveform inversion based on L 2 2 distance suffers from cycle skipping.
Expanding the radius of convergence relying on modifications of the objective function can mitigate local minima. In this paper, we propose a novel method to expand Long-wavelength FWI updates beyond cycle skipping. Qiu , J. Valenciano , and Y. Preview Abstract Full Waveform Inversion FWI success depends on producing seamless updates of the short- and long-wavelength features missing in the starting velocity model while avoiding cycle skipping. The use of cross-correlation gradients in FWI can lead to updates A penalty method for extended-waveform inversion based on discrepancy principle. Lei Fu and William W.
Preview Abstract Extended waveform inversion overcomes local minima obstacle by adding additional dimensions of freedom to the model, thus permitting it to fit the data well throughout the inversion process. These extra degrees of freedom must be curtailed at the solution, Model recovery below reflectors by optimal-transport FWI. Preview Abstract We analyze different velocity recovery mechanisms of full waveform inversion FWI and compare misfit functions based on the least-squares L 2 norm and optimal transport.
The focus will be on recovering velocity even below reflecting interfaces. Full-waveform inversion by model extension. This behavior is due to the presence of local minima in the FWI objective function. Direct envelope inversion and the inverse problem of Schrodinger impedance equation. Ru-Shan Wu. Preview Abstract Strong-scattering inversion or the inverse problem for strong scattering has different physical-mathematical foundations from the weak-scattering case.
In this paper I try to illustrate the connection between the Schrodinger inverse scattering inverse Decoupled elastic reflection traveltime inversion for improving S-wave velocity imaging. Preview Abstract Elastic reflection waveform inversion has great potential to update the low-wavenumber components of P- and S-velocities by relying on reflection kernels. However, the PP and SS mode wavepaths always overlap together due to the coupling effects of Elastic full-waveform inversion by b-spline projection.
Preview Abstract We explain a method of elastic full waveform inversion EFWI using the basis spline b-spline projections in data domain. Elastic-reflection waveform inversion with petrophysical model constraints. Daniel Rocha and Paul Sava. Preview Abstract Elastic wavefield tomography faces challenging pitfalls due to its multiparameter and multicomponent character, while seeking a model that generates accurate and high-quality images of the subsurface.
Inter-parameter crosstalk and absence of petrophysical Time-domain elastic Gauss-Newton full-waveform inversion: A matrix-free approach. Ke Chen and Mauricio D. The proposed algorithm consists of Trinh , R. Brossier , L. Preview Abstract Full waveform inversion FWI of onshore targets is very challenging due to the complex free-surface-related effects and 3D geometry representation. In such areas, the seismic wavefield is dominated by highly energetic and dispersive surface waves, Strategies for reducing crosstalk in viscoacoustic full-waveform inversion.
Scott Keating and Kristopher A. Preview Abstract Phenomena of seismic attenuation are both harmful to our ability to resolve elastic properties and of interest in their own right for quantitative interpretation. In applying methods of full waveform inversion on land, where low Q values are common in the Junxiao Li , Kristopher A. Innanen , Wenyong Pan , and Geng Yu. Preview Abstract In this study, a frequency-domain elastic full waveform inversion algorithm for 2-D VTI media has been developed. The forward problem used in this inversion algorithm is simulated by applying frequency domain finite difference method, which is a fast Target-oriented elastic full-waveform inversion through extended-migration redatuming.
Preview Abstract The high computational cost of elastic full-waveform inversion FWI limits its applicability to real exploration datasets; hence more simplistic and computationally cheaper methods are usually employed. However, these methods are affected by strong Waveform inversion based target-oriented redatuming. Qiang Guo and Tariq Alkhalifah. Preview Abstract Finding a velocity model that produces simulated data that fits the observed one is the main objective of full waveform inversion FWI.
To meet such an objective we often need to solve for a high-resolution delineation of the subsurface medium. Seismic inversion for a smooth velocity model using a wave-to-diffusion transform. Preview Abstract Non-linear seismic inversion faces difficulties with multiple local minima due to cycle skipping. It is possible to demonstrate that cycle skipping is unlikely to appear in the diffusive domain with a very common definition of the error functional. Robust reflection full-waveform inversion with exponential signal encoding.
Preview Abstract Although, with the usual seismic acquisition, much of the information about subsurface parameters is contained in the reflections data, many of the current Full Waveform Inversion applications still focus on the use of the transmitted energy i. Adriano Gomes and Zhuocheng Yang. This is an important step of the inversion process, since it not only affects the generation of the synthetic reflection data, but also the Aghamiry , A.
Gholami , and S. Preview Abstract Full waveform inversion FWI is a waveform matching procedure which can potentially provide subsurface models with a wavelength-scale resolution. However, sophisticated regularization techniques are required to decrease the sensitivity of FWI to the Full-waveform inversion with Mumford-Shah regularization. Preview Abstract Full-waveform inversion FWI is a non-linear procedure to estimate subsurface rock parameters from surface measurements of induced seismic waves. This procedure is ill-posed in nature and hence, requires regularization to enhance some structure depending Full-waveform inversion with prelearned dictionaries and nonlocal similarity.
Dongzhuo Li and Jerry M. Preview Abstract As a highly nonlinear and ill-posed problem, full waveform inversion FWI can be trapped in local minima, and suffers from reduced resolution due to limited aperture and source bandwidth. To steer the inversion process into a better direction and to Source-independent full-waveform inversion using an amplitude-semblance objective function. Preview Abstract Full-waveform inversion is a promising tool to produce accurate and high-resolution subsurface elastic models.
Accurate estimation of the source wavelet is required for most full-waveform inversion algorithms to obtain reliable inversion results. Time-domain reflection-based waveform inversion. Khalid Almuteri. Preview Abstract Full waveform inversion FWI is proven to be a successful high-resolution velocity model building tool, when low-frequency information and long-offset data are available.
Usually, the low-frequency is only available for the shallow section of the Reflection-intensity waveform inversion. Preview Abstract Conventional full waveform inversion FWI needs long offset data to update the deep structure of a velocity and low-frequency information to avoid cycle skipping with diving or refraction waves.
To reduce the data requirements, we propose an approach Keys to robust reflection-based full-waveform inversion. Preview Abstract Reflection based full waveform inversion RFWI is a category of approaches that employs a waveform-fitting-driven inversion process to build kinematically sound background models with reflections, which is usually a conventional full waveform inversion Preview Abstract Full waveform inversion FWI in recent years is widely used in the Gulf of Mexico area to optimize the accuracy and resolution of the subsurface velocity model.
A velocity model using tomography is heavily dependent on the signal-to-noise ratio of the Characterization of the Cascadia ocean margin methane hydrates using prestack waveform inversion and reverse time migration. Lingxiao Jia and Subhashis Mallick.
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Preview Abstract Cascadia ocean margin, offshore Washington, USA poses a major seismic and environmental hazard to the population centers of the northwestern United States and western Canada with 10,year record of magnitude 9 or greater earthquakes occurring in every Imtiaz Ahmed. Low-frequency compensation and its application in full-waveform inversion.
Jidong Yang and Hejun Zhu. Multi-scale strategy starting from low frequencies is a natural way to mitigate this problem. The success of multi-scale inversion requires the presence of effective low A robust full-waveform inversion based on a shifted correlation of the envelope of wavefields.
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