A novel time domain polarization filter based on a correlation matrix analysis

Geophysics ◽  
2020 ◽  
pp. 1-65
Author(s):  
Maher NASR ◽  
Bernard Giroux ◽  
J. Christian Dupuis
Keyword(s):  
Covariance Matrix ◽  
Time Domain ◽  
Linear Polarization ◽  
Seismic Data ◽  
Correlation Matrix ◽  
Data Matrix ◽  
Polarization Filter ◽  
Seismic Reflection Data ◽  
Filter Order ◽  
Svd Decomposition

Polarization filters are widely used for denoising seismic data. These filters are applied in the field of seismology, microseismic monitoring, vertical seismic profiling and subsurface imaging. They are primarily useful to suppress ground-roll in seismic reflection data and enhance P and S wave arrivals. Traditional implementations of the polarization filters involved the analysis of the covariance matrix or the SVD decomposition of a three-component seismogram matrix. The linear polarization level, known as rectilinearity, is expressed as a function of the covariance matrix eigenvalues or by the data matrix singular values. Wavefield records that are linearly polarized are amplified while others are attenuated. Besides the described implementations, we introduced a new time domain polarization filter based on the analysis of the seismic data correlation matrix. The principal idea is to extend the notion of the correlation coefficient in 3D space. This new filter avoids the need for diagonalization of the covariance matrix or SVD decomposition of data matrix, which are often time consuming. The new implementation facilitates the choice of the rectilinearity threshold: we demonstrate that linear polarization in 3D can be represented as three classic 2D correlations. A good linear polarization is detected when a high linear correlation between the three seismogram components is mutually observed. The tuning parameters of the new filter are the length of the time window, the filter order, and the rectilinearity threshold. Tests using synthetic seismograms show that optimal results are reached with a filter order that spans between 2 and 4, a rectilinearity threshold between 0.3 and 0.7, and a window length that is equivalent to one to three times the period of the signal wavelet. Compared to covariance-based filters, the new filter can enhance the signal-to-noise ratio by 6 to 20 dB and reduces computational costs by 25%.

scholarly journals Analysis of the covariance matrix in FWI through density of covariance maps

2020 ◽  
Vol 10 (1) ◽  
pp. 93-105
Author(s):  
Anyeres Neider Jimenez ◽  
Juan Carlos Muñoz Cuartas ◽  
Sheryl Avendaño ◽  
Leonardo Gómez Bernal
Keyword(s):  
Covariance Matrix ◽  
Seismic Data ◽  
Correlation Matrix ◽  
Hessian Matrix ◽  
Waveform Inversion ◽  
Full Waveform Inversion ◽  
R Matrix ◽  
Sources Of Uncertainty ◽  
Full Waveform ◽  
Estimation Of Uncertainties

Full waveform inversion (FWI) is a tool for the inversion of seismic data. There are several sources of uncertainty in the results provided by FWI. The quantification of such uncertainties has been studied through the resolution matrix (Res), which rests on a quadratic approximation that interprets the Hessian matrix as the posterior covariance matrix. Despite efforts in the use of Res, there is no published analysis of the uncertainties contained in the full correlation matrix, (R). Our approach leads to build the full R matrix, which, at the end of the day, is the final quantity that includes all the information associated with uncertainties.We focused on uncertainties related to variation in the starting models of the FWI, and thus propose a method to study the full R matrix, which is-called the Density of Correlation Map, D. By using the D map, we found that the highest uncertainty zones in the FWI inverted model are near the sources, the model boundaries, and the interfaces. We argue that D can be a complement for the study and estimation of uncertainties in FWI.

Study on the Improvement of MUSIC Algorithm Fire Wireless Communication

2014 ◽  
Vol 1049-1050 ◽  
pp. 1880-1884
Author(s):  
Bin Ni
Keyword(s):  
Covariance Matrix ◽  
Time Domain ◽  
Analytical Signal ◽  
Time Domain Analysis ◽  
Observation Time ◽  
Eigenvalue Decomposition ◽  
Target Range ◽  
Radio Communication ◽  
Music Algorithm ◽  
Good Spatial Resolution

Music algorithm has good spatial resolution, provides the possibility to further improve the performance of fire radio communication system, but the algorithm in the target range rapidly changing circumstances poor stability. Aiming at this problem, this paper proposes a MUSIC algorithm based on time domain analytical signals (TAMUSIC, Time-domain Analysis MUSIC). The TAMUISC algorithm first constructs analytical time-domain signal; then the time domain analytical signal covariance matrix; finally the covariance matrix eigenvalue decomposition, the noise subspace estimation results of spatial spectrum. The simulation results show that, TAMUSIC algorithm in target azimuth change quickly, compared with the conventional MUSIC algorithm, need a short observation time, observation has smaller variance.

Potentially Large Subsurface Gas Hydrate Bodies in the Mexican Ridges, Southwestern Gulf of Mexico

2021 ◽  
pp. 1-29
Author(s):  
Papia Nandi ◽  
Patrick Fulton ◽  
James Dale
Keyword(s):  
Gulf Of Mexico ◽  
Gas Hydrate ◽  
Seismic Data ◽  
Poor Quality ◽  
Reflection Point ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
High Impedance ◽  
Acoustic Velocities ◽  
Seismic Images

As rising ocean temperatures can destabilize gas hydrate, identifying and characterizing large shallow hydrate bodies is increasingly important in order to understand their hazard potential. In the southwestern Gulf of Mexico, reanalysis of 3D seismic reflection data reveals evidence for the presence of six potentially large gas hydrate bodies located at shallow depths below the seafloor. We originally interpreted these bodies as salt, as they share common visual characteristics on seismic data with shallow allochthonous salt bodies, including high-impedance boundaries and homogenous interiors with very little acoustic reflectivity. However, when seismic images are constructed using acoustic velocities associated with salt, the resulting images were of poor quality containing excessive moveout in common reflection point (CRP) offset image gathers. Further investigation reveals that using lower-valued acoustic velocities results in higher quality images with little or no moveout. We believe that these lower acoustic values are representative of gas hydrate and not of salt. Directly underneath these bodies lies a zone of poor reflectivity, which is both typical and expected under hydrate. Observations of gas in a nearby well, other indicators of hydrate in the vicinity, and regional geologic context, all support the interpretation that these large bodies are composed of hydrate. The total equivalent volume of gas within these bodies is estimated to potentially be as large as 1.5 gigatons or 10.5 TCF, considering uncertainty for estimates of porosity and saturation, comparable to the entire proven natural gas reserves of Trinidad and Tobago in 2019.

scholarly journals Improved Interpretation of Deep Seismic Reflection Data in Areas of Complex Geology Through Integration With Passive Seismic Data Sets

2018 ◽  
Vol 123 (12) ◽  
pp. 10,810-10,830
Author(s):  
Michael Dentith ◽  
Huaiyu Yuan ◽  
Ruth Elaine Murdie ◽  
Perla Pina-Varas ◽  
Simon P. Johnson ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Data Sets ◽  
Seismic Reflection Data ◽  
Deep Seismic Reflection ◽  
Reflection Data ◽  
Passive Seismic ◽  
Complex Geology

3D constraints and finite-difference modeling of massive sulfide deposits: The Kristineberg seismic lines revisited, northern Sweden

Geophysics ◽  
2012 ◽  
Vol 77 (5) ◽  
pp. WC69-WC79 ◽  
Author(s):  
Mahdieh Dehghannejad ◽  
Alireza Malehmir ◽  
Christopher Juhlin ◽  
Pietari Skyttä
Keyword(s):  
Finite Difference ◽  
Seismic Data ◽  
Massive Sulfide ◽  
Northern Sweden ◽  
Seismic Reflection Data ◽  
Sulfide Deposits ◽  
Time Migration ◽  
Massive Sulfide Deposits ◽  
Prestack Time Migration ◽  
Seismic Lines

The Kristineberg mining area in the western part of the Skellefte ore district is the largest base metal producer in northern Sweden and currently the subject of extensive geophysical and geologic studies aimed at constructing 3D geologic models. Seismic reflection data form the backbone of the geologic modeling in the study area. A geologic cross section close to the Kristineberg mine was used to generate synthetic seismic data using acoustic and elastic finite-difference algorithms to provide further insight about the nature of reflections and processing challenges when attempting to image the steeply dipping structures within the study area. Synthetic data suggest processing artifacts manifested themselves in the final 2D images as steeply dipping events that could be confused with reflections. Fewer artifacts are observed when the data are processed using prestack time migration. Prestack time migration also was performed on high-resolution seismic data recently collected near the Kristineberg mine and helped to image a high-amplitude, gently dipping reflection occurring stratigraphically above the extension of the deepest Kristineberg deposit. Swath 3D processing was applied to two crossing seismic lines, west of the Kristineberg mine, to provide information on the 3D geometry of an apparently flat-lying reflection observed in both of the profiles. The processing indicated that the reflection dips about 30° to the southwest and is generated at the contact between metasedimentary and metavolcanic rocks, the upper part of the latter unit being the most typical stratigraphic level for the massive sulfide deposits in the Skellefte district.

Late Cretaceous – Cenozoic history of the transition zone between the East European Craton and the Paleozoic Platform, Polish sector of the Baltic Sea, revealed by new offshore regional seismic reflection data (BALTEC project)

2021 ◽  
Author(s):  
Piotr Krzywiec ◽  
Łukasz Słonka ◽  
Quang Nguyen ◽  
Michał Malinowski ◽  
Mateusz Kufrasa ◽  
...  
Keyword(s):  
High Resolution ◽  
Late Cretaceous ◽  
Seismic Data ◽  
Seismic Reflection ◽  
Upper Cretaceous ◽  
Seismic Reflection Data ◽  
East European ◽  
Reflection Data ◽  
Multichannel Seismic Reflection ◽  
Multichannel Seismic Reflection Data

<p>In 2016, approximately 850 km of high-resolution multichannel seismic reflection data of the BALTEC survey have been acquired offshore Poland within the transition zone between the East European Craton and the Paleozoic Platform. Data processing, focused on removal of multiples, strongly overprinting geological information at shallower intervals, included SRME, TAU-P domain deconvolution, high resolution parabolic Radon demultiple and SWDM (Shallow Water De-Multiple). Entire dataset was Kirchhoff pre-stack time migrated. Additionally, legacy shallow high-resolution multichannel seismic reflection data acquired in this zone in 1997 was also used. All this data provided new information on various aspects of the Phanerozoic evolution of this area, including Late Cretaceous to Cenozoic tectonics and sedimentation. This phase of geological evolution could be until now hardly resolved by analysis of industry seismic data as, due to limited shallow seismic imaging and very strong overprint of multiples, essentially no information could have been retrieved from this data for first 200-300 m. Western part of the BALTEC dataset is located above the offshore segment of the Mid-Polish Swell (MPS) – large anticlinorium formed due to inversion of the axial part of the Polish Basin. BALTEC seismic data proved that Late Cretaceous inversion of the Koszalin – Chojnice fault zone located along the NE border of the MPS was thick-skinned in nature and was associated with substantial syn-inversion sedimentation. Subtle thickness variations and progressive unconformities imaged by BALTEC seismic data within the Upper Cretaceous succession in vicinity of the Kamień-Adler and the Trzebiatów fault zones located within the MPS documented complex interplay of Late Cretaceous basin inversion, erosion and re-deposition. Precambrian basement of the Eastern, cratonic part of the study area is overlain by Cambro-Silurian sedimentary cover. It is dissected by a system of steep, mostly reverse faults rooted in most cases in the deep basement. This fault system has been regarded so far as having been formed mostly in Paleozoic times, due to the Caledonian orogeny. As a consequence, Upper Cretaceous succession, locally present in this area, has been vaguely defined as a post-tectonic cover, locally onlapping uplifted Paleozoic blocks. New seismic data, because of its reliable imaging of the shallowest substratum, confirmed that at least some of these deeply-rooted faults were active as a reverse faults in latest Cretaceous – earliest Paleogene. Consequently, it can be unequivocally proved that large offshore blocks of Silurian and older rocks presently located directly beneath the Cenozoic veneer must have been at least partly covered by the Upper Cretaceous succession; then, they were uplifted during the widespread inversion that affected most of Europe. Ensuing regional erosion might have at least partly provided sediments that formed Upper Cretaceous progradational wedges recently imaged within the onshore Baltic Basin by high-end PolandSPAN regional seismic data. New seismic data imaged also Paleogene and younger post-inversion cover. All these results prove that Late Cretaceous tectonics substantially affected large areas located much farther towards the East than previously assumed.</p><p>This study was funded by the Polish National Science Centre (NCN) grant no UMO-2017/27/B/ST10/02316.</p>

Using time domain seismic data for history matching processes

First Break ◽  
2011 ◽  
Vol 29 (1770) ◽  
Author(s):  
E. Tillier ◽  
M. Le Ravalec ◽  
F. Roggero
Keyword(s):  
Time Domain ◽  
Seismic Data ◽  
History Matching
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