Data‐driven adaptive decomposition of multicomponent seabed recordings

Geophysics ◽  
2004 ◽  
Vol 69 (5) ◽  
pp. 1329-1337 ◽  
Author(s):  
Remco Muijs ◽  
Johan O. A. Robertsson ◽  
Klaus Holliger
Keyword(s):  
Water Layer ◽  
P Wave ◽  
Data Driven ◽  
Minimal Amount ◽  
S Wave ◽  
Sea Floor ◽  
Decomposition Scheme ◽  
Wave Potential ◽  
Dual Sensor ◽  
Adaptive Decomposition

Dual‐sensor (hydrophone and three‐component geophone) data recorded on the sea floor allow the elastic wavefield to be decomposed into its upgoing and downgoing P‐ and S‐wave components. Most decomposition algorithms require accurate knowledge of the elastic properties of the sea floor in the vicinity of the receivers and properly calibrated sensors, in order for the data to be a faithful vector representation of the ground motion. We present a multistep adaptive decomposition scheme that provides the necessary information directly from the data by imposing constraints on intermediate decomposition results. The proposed scheme requires no a priori information and only a minimal amount of user‐defined input, thus allowing multicomponent data to be decomposed in an automated data‐driven fashion. The performance of the technique is illustrated using seabed data acquired in the North Sea with prototype single sensors (multicomponent geophones individually sampled). Realistic sea floor properties and sensor calibration operators are obtained, and elastic decomposition of the calibrated data generally yields good results. Dominant water‐layer reverberations are successfully attenuated and primary reflections are substantially enhanced in the computed upgoing P‐wave potential just below the sea floor. In contrast, the result for the upgoing S‐wave potential is somewhat less convincing; although the energy of water‐layer multiples is substantially reduced, notable amounts of undesired multiple energy remain in this section after decomposition, particularly at high offsets. These imperfections may point to inaccuracies in the parametrization of the sea floor or remaining inaccuracies in the vector fidelity of the horizontal geophone recordings. Nevertheless, the results obtained with the extended data‐driven decomposition scheme are at least comparable to previously published results.

Guidelines for building a detailed elastic depth model

Geophysics ◽  
2000 ◽  
Vol 65 (1) ◽  
pp. 35-45
Author(s):  
Jarrod C. Dunne ◽  
Greg Beresford ◽  
Brian L. N Kennett
Keyword(s):  
Wave Velocity ◽  
Mode Conversion ◽  
Poisson Ratio ◽  
Velocity Model ◽  
P Wave ◽  
Time Interval ◽  
S Wave ◽  
Sea Floor ◽  
P Wave Velocity ◽  
Inelastic Attenuation

We developed guidelines for building a detailed elastic depth model by using an elastic synthetic seismogram that matched both prestack and stacked marine seismic data from the Gippsland Basin (Australia). Recomputing this synthetic for systematic variations upon the depth model provided insight into how each part of the model affected the synthetic. This led to the identification of parameters in the depth model that have only a minor influence upon the synthetic and suggested methods for estimating the parameters that are important. The depth coverage of the logging run is of prime importance because highly reflective layering in the overburden can generate noise events that interfere with deeper events. A depth sampling interval of 1 m for the P-wave velocity model is a useful lower limit for modeling the transmission response and thus maintaining accuracy in the tie over a large time interval. The sea‐floor model has a strong influence on mode conversion and surface multiples and can be built using a checkshot survey or by testing different trend curves. When an S-wave velocity log is unavailable, it can be replaced using the P-wave velocity model and estimates of the Poisson ratio for each significant geological formation. Missing densities can be replaced using Gardner’s equation, although separate substitutions are required for layers known to have exceptionally high or low densities. Linear events in the elastic synthetic are sensitive to the choice of inelastic attenuation values in the water layer and sea‐floor sediments, while a simple inelastic attenuation model for the consolidated sediments is often adequate. The usefulness of a 1-D depth model is limited by misties resulting from complex 3-D structures and the validity of the measurements obtained in the logging run. The importance of such mis‐ties can be judged, and allowed for in an interpretation, by recomputing the elastic synthetic after perturbing the depth model to simulate the key uncertainties. Taking the next step beyond using simplistic modeling techniques requires extra effort to achieve a satisfactory tie to each part of a prestack seismic record. This is rewarded by the greater confidence that can then be held in the stacked synthetic tie and applications such as noise identification, data processing benchmarking, AVO analysis, and inversion.

S-S imaging with vertical-force sources

2014 ◽  
Vol 2 (2) ◽  
pp. SE29-SE38 ◽  
Author(s):  
Bob A. Hardage ◽  
Donald Wagner
Keyword(s):  
Seismic Data ◽  
P Wave ◽  
Energy Sources ◽  
Minimal Amount ◽  
Equal Weight ◽  
Vertical Force ◽  
3D Seismic ◽  
S Wave ◽  
Receiver Arrays ◽  
3D Seismic Data

We show examples of S-S images created from multicomponent seismic data generated by vertical-force sources that can be quite useful to seismic interpreters. Two source types are used: vertical vibrators and shot-hole explosives. We first discuss S-S images made from data generated by a vertical vibrator and recorded with vertical receiver arrays of 3C geophones. We next show images extracted from surface-based 3C geophones deployed around this VSP well as a 3D seismic grid. The energy sources used to generate these surface 3D seismic data were shot-hole explosives. In all data examples, we observe that each type of vertical-force source (vertical vibrator and shot-hole explosive) produces abundant direct-S energy on radial and transverse geophones. We find only minimal amounts of P-wave energy on transverse-receiver data. In contrast, radial-receiver data have significant P-wave events intermingled with radial-S events. The minimal amount of P-wave noise on transverse-receiver data makes it easier to study S-S wave physics and to create S-S images with transverse-S data. The data examples focus on transverse-S data created by vertical-force sources because interpreters will find it more convenient to process and use this S-mode. Subsequent publications will assign equal weight to radial-S and transverse-S data.

Extraction of P‐ and S‐waves from the vertical component of the particle velocity at the sea floor

Geophysics ◽  
1995 ◽  
Vol 60 (1) ◽  
pp. 231-240 ◽  
Author(s):  
Lasse Amundsen ◽  
Arne Reitan
Keyword(s):  
Particle Velocity ◽  
Synthetic Data ◽  
Vertical Component ◽  
Transversely Isotropic ◽  
Vertical Axis ◽  
Elastic Stiffness ◽  
P Wave ◽  
S Wave ◽  
Sea Floor ◽  
S Waves

At the boundary between two solid media in welded contact, all three components of particle velocity and vertical traction are continuous through the boundary. Across the boundary between a fluid and a solid, however, only the vertical component of particle velocity is continuous while the horizontal components can be discontinuous. Furthermore, the pressure in the fluid is the negative of the vertical component of traction in the solid, while the horizontal components of traction vanish at the interface. Taking advantage of this latter fact, we show that total P‐ and S‐waves can be computed from the vertical component of the particle velocity recorded by single component geophones planted on the sea floor. In the case when the sea floor is transversely isotropic with a vertical axis of symmetry, the computation requires the five independent elastic stiffness components and the density. However, when the sea floor material is fully isotropic, the only material parameter needed is the local shear wave velocity. The analysis of the extraction problem is done in the slowness domain. We show, however, that the S‐wave section can be obtained by a filtering operation in the space‐frequency domain. The P‐wave section is then the difference between the vertical component of the particle velocity and the S‐wave component. A synthetic data example demonstrates the performance of the algorithm.

Adaptive decomposition of multicomponent ocean‐bottom seismic data into downgoing and upgoing P‐ and S‐waves

Geophysics ◽  
2003 ◽  
Vol 68 (3) ◽  
pp. 1091-1102 ◽  
Author(s):  
K. M. Schalkwijk ◽  
C. P. A. Wapenaar ◽  
D. J. Verschuur
Keyword(s):  
Ocean Bottom ◽  
S Wave ◽  
Depth Level ◽  
S Waves ◽  
Decomposition Scheme ◽  
Adaptive Decomposition ◽  
The Individual ◽  
Event Definition ◽  
Wavefield Decomposition ◽  
Shallow Water Depth

With wavefield decomposition, the recorded wavefield at a certain depth level can be separated into upgoing and downgoing wavefields as well as into P‐ and S‐waves. The medium parameters at the considered depth level (e.g., just below the ocean‐bottom) need to be known in order to be able to do a decomposition. In general, these parameters are unknown and, in addition, measurement‐related issues, such as geophone coupling and crosstalk between the different components, need to be dealt with. In order to apply decomposition to field data, an adaptive five‐stage decomposition scheme was developed in which these issues are addressed. In this study, the adaptive decomposition scheme is tested on a data example with a relatively shallow water depth (∼120 m), consisting recordings from of a full line of ocean‐bottom receivers. Although some of the individual stages in the decomposition scheme are more difficult to apply because of stronger interference between events compared to data acquired over deeper water, the end result is satisfying. Also, a good decomposition result is obtained for the S‐waves. The extension of the decomposition scheme to a complete line of ocean‐bottom cable data consists of a repeated application of the procedure for each receiver. The resulting decomposed upgoing P‐ and S‐wavefields are processed, yielding poststack time migrated images of the subsurface. Comparison with the images obtained from the original (i.e., not decomposed) measurements shows that wavefield decomposition just below the ocean bottom leads to a strong attenuation of multiply reflected events at the sea surface and better event definition in both P‐ and S‐wave sections. Other decomposition effects like improved angle‐dependent amplitudes cannot be evaluated in this way.

Decomposition of multicomponent sea‐floor data into upgoing and downgoing P‐ and S‐waves

Geophysics ◽  
1995 ◽  
Vol 60 (2) ◽  
pp. 563-572 ◽  
Author(s):  
Lasse Amundsen ◽  
Arne Reitan
Keyword(s):  
Particle Velocity ◽  
Layered Medium ◽  
Synthetic Data ◽  
Water Layer ◽  
S Wave ◽  
Sea Floor ◽  
S Waves ◽  
Sea Bottom ◽  
Marine Source ◽  
Horizontal Particle

A method for decomposing multicomponent sea‐floor measurements into upgoing and downgoing P‐ and S‐waves is presented. We assume that a marine survey employing a marine source in the water layer is conducted over a plane‐layered medium. From recordings of the pressure just above the sea floor and the particle velocity vector just below the sea floor, decomposition filters can be determined by plane‐wave analysis. The decomposition filter coefficients depend on the P‐ and S‐wave velocities and the density at the sea bottom. We show how to decompose the multicomponent measurements into upgoing and downgoing P‐ and S‐vertical traction components, vertical‐particle velocity components, and horizontal particle velocity components. The decomposition filters are applied with good results to synthetic data modeled in a plane‐layered medium.

Experimental Analogy Method for Measuring S-Wave Slowness of Low Porosity and Low Permeability Reservoir

2013 ◽  
Vol 318 ◽  
pp. 385-389 ◽  
Author(s):  
Zhong Hao Wang ◽  
Fei Li Qin
Keyword(s):  
Water Saturation ◽  
Water Layer ◽  
Linear Interpolation ◽  
P Wave ◽  
Formation Condition ◽  
Low Permeability ◽  
S Wave ◽  
Log Data ◽  
Experimental Scheme ◽  
Low Porosity

Fracturing technology is one of the most efficient ways to productivity evaluation, and the key of fracturing technology is how to describe rock mechanical behaviors to which S-wave slowness is an important parameter. According to the complexities of low porosity and low permeability of Pucheng oilfield, we designed and obtained the experimental scheme for measuring the velocities of P-wave and S-wave. The samples are focus on dry sample and rock with water saturation 100%, 80%, 60% and 40% respectively, under two conditions at normal temperature with 5MPa and with formation pressure at 90°C. By conducting triaxial test, the velocities of P-wave and S-wave under different temperatures and different pressures were obtained. On the analysis of 26 groups of data, the results showed that on the formation condition, S-wave slowness value varied linearly with water saturation, and S-wave slowness was also linear to P-wave slowness at different water saturation. Oil-bearing layer and water layer models were created separately, to compute S-wave through P-wave based on linear interpolation. We validated the new approach with an example from real array acoustic log data of Pushen 18 well. The results demonstrated the advantages of this method over empirical equation proposed by Entwisle’s and Dreiser Company. The relative error from them compared with log data are more than 10% whereas that of our method is 4.2%.

scholarly journals Teleseismic earthquake wavefields observed on the Ross Ice Shelf

2020 ◽  
pp. 1-17
Author(s):  
Michael G. Baker ◽  
Richard C. Aster ◽  
Douglas A. Wiens ◽  
Andrew Nyblade ◽  
Peter D. Bromirski ◽  
...  
Keyword(s):  
Solid Earth ◽  
Water Column ◽  
Lamb Waves ◽  
Body Wave ◽  
Water Layer ◽  
P Wave ◽  
S Wave ◽  
Ice Shelf ◽  
Geographic Variations ◽  
Ross Ice Shelf

Abstract Observations of teleseismic earthquakes using broadband seismometers on the Ross Ice Shelf (RIS) must contend with environmental and structural processes that do not exist for land-sited seismometers. Important considerations are: (1) a broadband, multi-mode ambient wavefield excited by ocean gravity wave interactions with the ice shelf; (2) body wave reverberations produced by seismic impedance contrasts at the ice/water and water/seafloor interfaces and (3) decoupling of the solid Earth horizontal wavefield by the sub-shelf water column. We analyze seasonal and geographic variations in signal-to-noise ratios for teleseismic P-wave (0.5–2.0 s), S-wave (10–15 s) and surface wave (13–25 s) arrivals relative to the RIS noise field. We use ice and water layer reverberations generated by teleseismic P-waves to accurately estimate the sub-station thicknesses of these layers. We present observations consistent with the theoretically predicted transition of the water column from compressible to incompressible mechanics, relevant for vertically incident solid Earth waves with periods longer than 3 s. Finally, we observe symmetric-mode Lamb waves generated by teleseismic S-waves incident on the grounding zones. Despite their complexity, we conclude that teleseismic coda can be utilized for passive imaging of sub-shelf Earth structure, although longer deployments relative to conventional land-sited seismometers will be necessary to acquire adequate data.

scholarly journals Post-collisional mantle delamination in the Dinarides implied from staircases of Oligo-Miocene uplifted marine terraces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philipp Balling ◽  
Christoph Grützner ◽  
Bruno Tomljenović ◽  
Wim Spakman ◽  
Kamil Ustaszewski
Keyword(s):  
Balkan Peninsula ◽  
Receiver Functions ◽  
P Wave ◽  
S Wave ◽  
Slab Geometry ◽  
Surface Uplift ◽  
River Incision ◽  
Marine Terraces ◽  
Convergence System ◽  
Internal Dinarides

AbstractThe Dinarides fold-thrust belt on the Balkan Peninsula resulted from convergence between the Adriatic and Eurasian plates since Mid-Jurassic times. Under the Dinarides, S-wave receiver functions, P-wave tomographic models, and shear-wave splitting data show anomalously thin lithosphere overlying a short down-flexed slab geometry. This geometry suggests a delamination of Adriatic lithosphere. Here, we link the evolution of this continental convergence system to hitherto unreported sets of extensively uplifted Oligocene–Miocene (28–17 Ma) marine terraces preserved at elevations of up to 600 m along the Dinaric coastal range. River incision on either side of the Mediterranean-Black Sea drainage divide is comparable to the amounts of terrace uplift. The preservation of the uplifted terraces implies that the most External Dinarides did not experience substantial deformation other than surface uplift in the Neogene. These observations and the contemporaneous emplacement of igneous rocks (33–22 Ma) in the internal Dinarides suggest that the Oligo-Miocene orogen-wide uplift was driven by post-break-off delamination of the Adriatic lithospheric mantle, this was followed by isostatic readjustment of the remaining crust. Our study details how lithospheric delamination exerts an important control on crustal deformation and that its crustal signature and geomorphic imprint can be preserved for millions of years.

scholarly journals S-wave experiments for the exploration of a deep geothermal carbonate reservoir in the German Molasse Basin

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Britta Wawerzinek ◽  
Hermann Buness ◽  
Hartwig von Hartmann ◽  
David C. Tanner
Keyword(s):  
Upper Jurassic ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Seismic Survey ◽  
Seismic Exploration ◽  
Molasse Basin ◽  
S Wave ◽  
Induced Earthquakes ◽  
Conversion Point ◽  
Facies Classification

AbstractThere are many successful geothermal projects that exploit the Upper Jurassic aquifer at 2–3 km depth in the German Molasse Basin. However, up to now, only P-wave seismic exploration has been carried out. In an experiment in the Greater Munich area, we recorded S-waves that were generated by the conventional P-wave seismic survey, using 3C receivers. From this, we built a 3D volume of P- to S-converted (PS) waves using the asymptotic conversion point approach. By combining the P-volume and the resulting PS-seismic volume, we were able to derive the spatial distribution of the vp/vs ratio of both the Molasse overburden and the Upper Jurassic reservoir. We found that the vp/vs ratios for the Molasse units range from 2.0 to 2.3 with a median of 2.15, which is much higher than previously assumed. This raises the depth of hypocenters of induced earthquakes in surrounding geothermal wells. The vp/vs ratios found in the Upper Jurassic vary laterally between 1.5 and 2.2. Since no boreholes are available for verification, we test our results against an independently derived facies classification of the conventional 3D seismic volume and found it correlates well. Furthermore, we see that low vp/vs ratios correlate with high vp and vs velocities. We interpret the latter as dolomitized rocks, which are connected with enhanced permeability in the reservoir. We conclude that 3C registration of conventional P-wave surveys is worthwhile.

Inverse design of layered periodic wave barriers based on deep learning

2021 ◽  
pp. 146442072110168
Author(s):  
Chen-Xu Liu ◽  
Gui-Lan Yu
Keyword(s):  
Deep Learning ◽  
Activation Function ◽  
Periodic Wave ◽  
P Wave ◽  
Soil Parameters ◽  
S Wave ◽  
Output Frequency ◽  
Great Generality ◽  
Typical Range ◽  
Deep Learning Model

This study presents an approach based on deep learning to design layered periodic wave barriers with consideration of typical range of soil parameters. Three cases are considered where P wave and S wave exist separately or simultaneously. The deep learning model is composed of an autoencoder with a pretrained decoder which has three branches to output frequency attenuation domains for three different cases. A periodic activation function is used to improve the design accuracy, and condition variables are applied in the code layer of the autoencoder to meet the requirements of practical multi working conditions. Forty thousand sets of data are generated to train, validate, and test the model, and the designed results are highly consistent with the targets. The presented approach has great generality, feasibility, rapidity, and accuracy on designing layered periodic wave barriers which exhibit good performance in wave suppression in targeted frequency range.

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