Multicomponent seismology—The next wave

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 49-49 ◽  
Author(s):  
Thomas L. Davis
Keyword(s):  
Measurement System ◽  
Seismic Data ◽  
Body Waves ◽  
Ground Displacement ◽  
S Waves ◽  
Sea Bottom ◽  
Full Complement ◽  
Seismic Acquisition ◽  
Fourth Component ◽  
Three Components

Multicomponent seismology requires recording of seismic data with three‐ and sometimes four‐component receivers. The three components measure displacement of the ground, usually in two horizontal and one vertical directions. The fourth component is a measurement of pressure, which is used in sea‐bottom surveys. Measuring three components of ground displacement enables the recording of compressional (P) and shear (S) waves which represent the full complement of “body” waves in seismology. Earthquake seismologists have been using the full complement for years to interpret the structure of our living planet; however, exploration seismologists have been slow to bring multicomponent seismology to the forefront of their measurement system. This is finally changing. Thanks to new seismic acquisition recording systems, it is now feasible to economically record multicomponent seismic data in both land and marine (sea‐bottom) settings. In the future, all land or sea‐bottom seismic data will be recorded by multicomponent technology, thereby bringing us the next wave of exploration geophysics as we begin to “see the unseen.”

Passive Seismic Marchenko Imaging

2020 ◽  
Author(s):  
Zhongyuan Jin
Keyword(s):  
Free Surface ◽  
Seismic Data ◽  
Low Cost ◽  
Body Waves ◽  
Seismic Survey ◽  
Significant Difference ◽  
Passive Seismic ◽  
Seismic Acquisition ◽  
Imaging Property ◽  
Internal Multiples

<p>In recent years, seismic interferometry (SI) has been widely used in passive seismic data, it allows to retrieve new seismic responses among physical receivers by cross-correlation or multidimensional deconvolution (MDD). Retrieval of reflected body waves from passive seismic data has been proved to be feasible. Marchenko method, as a new technique, retrieves Green’s functions directly inside the medium without any physical receiver there. Marchenko method retrieves precise Green’s functions and the up-going and down-going Green’s functions can be used in target-oriented Marchenko imaging, and internal multiples related artifacts in Marchenko image can be suppressed. </p><p>Conventional Marchenko imaging uses active seismic data, in this abstract, we propose the method of passive seismic Marchenko imaging (PSMI) which retrieves Green’s functions from ambient noise signal. PSMI employs MDD method to obtain the reflection response without free-surface interaction as an input for Marchenko algorithm, such that free-surface multiples in the retrieved shot gathers can be eliminated, besides, internal multiples don’t contribute to final Marchenko image, which means both free-surface multiples and internal multiples have been taken into account. Although the retrieved shot gathers are contaminated by noises, the up-going and down-going Green’s functions can be still retrieved. Results of numerical tests validate PSMI’s feasibility and robustness. PSMI provides a new way to image the subsurface structure, it combines the low-cost property of passive seismic acquisition and target-oriented imaging property of Marchenko imaging, as well as the advantage that there are no artifacts caused by internal multiples and free-surface multiples.</p><p>Overall, the significant difference between PSMI and conventional Marchenko imaging is that passive seismic data is used into Marchenko scheme, which extends the Marchenko imaging to passive seismic field. Passive seismic Marchenko imaging avoids the effects of free-surface multiples and internal multiples in the retrieved shot gathers. PSMI combines the low-cost property of passive seismic acquisition and target-oriented imaging property of Marchenko imaging which is promising in future field seismic survey.</p><p>This work is supported by the Fundamental Research Funds for the Central Universities (JKY201901-03). </p>

Pre-stack sea bottom detection and swell correction within an expected hyperbolic range for noisy high-resolution 8-channel airgun seismic data

2021 ◽  
Vol 42 (1) ◽  
Author(s):  
Ho-Young Lee ◽  
Nam-Hyung Koo ◽  
Byoung-Yeop Kim ◽  
Young-Jun Kim ◽  
Woohyun Son ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Sea Bottom

Kirchhoff elastic wave migration for the case of noncoincident source and receiver

Geophysics ◽  
1984 ◽  
Vol 49 (8) ◽  
pp. 1223-1238 ◽  
Author(s):  
John T. Kuo ◽  
Ting‐fan Dai
Keyword(s):  
Elastic Wave ◽  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Horizontal Layer ◽  
P Wave ◽  
Seismic Section ◽  
S Waves ◽  
Surface Data ◽  
Marine Seismic ◽  
Wave Migration

In taking into account both compressional (P) and shear (S) waves, more geologic information can likely be extracted from the seismic data. The presence of shear and converted shear waves in both land and marine seismic data recordings calls for the development of elastic wave‐migration methods. The migration method presently developed consists of simultaneous migration of P- and S-waves for offset seismic data based on the Kirchhoff‐Helmholtz type integrals for elastic waves. A new principle of simultaneously migrating both P- and S-waves is introduced. The present method, named the Kirchhoff elastic wave migration, has been tested using the 2-D synthetic surface data calculated from several elastic models of a dipping layer (including a horizontal layer), a composite dipping and horizontal layer, and two layers over a half‐space. The results of these tests not only assure the feasibility of this migration scheme, but also demonstrate that enhanced images in the migrated sections are well formed. Moreover, the signal‐to‐noise ratio increases in the migrated seismic section by this elastic wave migration, as compared with that using the Kirchhoff acoustic (P-) wave migration alone. This migration scheme has about the same order of sensitivity of migration velocity variations, if [Formula: see text] and [Formula: see text] vary concordantly, to the recovery of the reflector as that of the Kirchhoff acoustic (P-) wave migration. In addition, the sensitivity of image quality to the perturbation of [Formula: see text] has also been tested by varying either [Formula: see text] or [Formula: see text]. For varying [Formula: see text] (with [Formula: see text] fixed), the migrated images are virtually unaffected on the [Formula: see text] depth section while they are affected on the [Formula: see text] depth section. For varying [Formula: see text] (with [Formula: see text] fixed), the migrated images are affected on both the [Formula: see text] and [Formula: see text] depth sections.

A 108km2 Compressive Sensing Processing Trial

2021 ◽  
Author(s):  
Dustin Blymyer ◽  
Klaas Koster ◽  
Graeme Warren
Keyword(s):  
Compressive Sensing ◽  
Surface Waves ◽  
Seismic Data ◽  
High Frequency ◽  
Quality Data ◽  
Low Velocity ◽  
Conventional Design ◽  
Seismic Acquisition ◽  
Similar Cost ◽  
Station Density

Abstract Summary Compressive sensing (CS) of seismic data is a new style of seismic acquisition whereby the data are recorded on a pseudorandom grid rather than along densely sampled lines in a conventional design. A CS design with a similar station density will generally yield better quality data at a similar cost compared to a conventional design, whereas a CS design with a lower station density will reduce costs while retaining quality. Previous authors (Mosher, 2014) have shown good results from CS surveys using proprietary methods for the design and processing. In this paper we show results obtained using commercially available services based on published algorithms (Lopez, 2016). This is a necessary requirement for adoption of CS by our industry. This report documents the results of a 108km2 CS acquisition and processing trial. The acquisition and processing were specifically designed to establish whether CS can be used for suppression of backscattered, low velocity, high frequency surface waves. We demonstrate that CS data can be reconstructed by a commercial contractor and that the suppression of backscattered surface waves is improved by using CS receiver gathers reconstructed to a dense shot grid. We also show that CS acquisition is a reliable alternative to conventional acquisition from which high-quality subsurface images can be formed.

Imaging below a complex overburden with borehole-seismic data

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. S135-S150
Author(s):  
Jakob B. U. Haldorsen ◽  
Leif Jahren
Keyword(s):  
Economic Evaluation ◽  
Seismic Data ◽  
Seismic Profile ◽  
Profile Data ◽  
Vertical Seismic Profile ◽  
S Waves ◽  
Critical Information ◽  
Measured Polarization ◽  
Borehole Seismic

We have determined how the measured polarization and traveltime for P- and S-waves can be used directly with vertical seismic profile data for estimating the salt exit points in a salt-proximity survey. As with interferometry, the processes described use only local velocities. For the data analyzed in this paper, our procedures have confirmed the location, inferred from surface-seismic data, of the flank of a steeply dipping salt body near the well. This has provided us more confidence in the estimated reservoir extent moving toward the salt face, which in turn has added critical information for the economic evaluation of a possible new well into the reservoir. We also have found that ray-based vector migration, based on the assumptions of locally plane wavefronts and locally plane formation interfaces, can be used to create 3D reflection images of steeply dipping sediments near the well, again using only local velocities. Our local reflection images have helped confirm the dips of the sediments between the well and the salt flank. Because all parameters used in these processes are local and can be extracted from the data themselves, the processes can be considered to be self-sufficient.

Automated microseismic event location by amplitude stacking and semblance

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. KS191-KS210 ◽  
Author(s):  
Chengwei Zhang ◽  
Wenxiao Qiao ◽  
Xiaohua Che ◽  
Junqiang Lu ◽  
Baiyong Men
Keyword(s):  
Body Waves ◽  
S Waves ◽  
Advantages And Disadvantages ◽  
Location Uncertainty ◽  
Event Location ◽  
Time Average ◽  
Microseismic Events ◽  
Location Methods ◽  
Microseismic Event Location ◽  
Microseismic Event

Without the need to pick the arrival times of P- and S-waves, migration-based location methods, such as semblance-based and amplitude-stacking-based location methods, are best applied to microseismic events. By comparing and analyzing the advantages and disadvantages of these two methods, we have developed a new location method using amplitude information and semblance. First, we use the two-point ray-tracing method to calculate the traveltime of body waves from the trial point to each receiver, which determines the time-window positions of the P- and S-waves on all traces. Then, we calculate the semblance of the waveforms and the amplitude stacking of the ratio between the short-time average and the long-time average is computed upon the original waveform over the windows. Finally, the semblance weighted by amplitude stacking is used to image the spatial location of the microseismic events. Using experimental and synthetic data considering different factors that may affect the location result (e.g., the signal-to-noise ratio of the waveforms, the scale of the observation array, and the horizontal and vertical distances from the source to fracture zones), we perform microseismic event location with all three methods. According to the source imaging results from experimental and synthetic tests, the semblance method has great location uncertainty in the radial direction but it has good constraints in the circumferential direction; the amplitude-stacking method exhibits the opposite result; and the weighted-semblance method has good constraints in the circumferential and radial directions because it inherits the advantages of semblance-based and amplitude-stacking-based methods. Therefore, compared with existing migration-based location methods, our weighted-semblance method indicates stronger stability and lower location uncertainty, even when downhole monitoring is conducted with a limited aperture of the receiver array.

Recording the Aurora at Seismometers across Alaska

2020 ◽  
Vol 91 (6) ◽  
pp. 3039-3053 ◽  
Author(s):  
Carl Tape ◽  
Adam T. Ringler ◽  
Don L. Hampton
Keyword(s):  
Magnetic Field ◽  
Seismic Data ◽  
Vertical Component ◽  
Seismic Array ◽  
Magnetic Shielding ◽  
Data Sets ◽  
S Waves ◽  
Auroral Activity ◽  
Seismic Sensors ◽  
Magnetometer Data

Abstract We examine three continuously recording data sets related to the aurora: all-sky camera images, three-component magnetometer data, and vertical-component, broadband seismic data as part of the EarthScope project (2014 to present). Across Alaska there are six all-sky cameras, 13 magnetometers, and >200 seismometers. The all-sky images and magnetometers have the same objective, which is to monitor space weather and improve our understanding of auroral activity, including the influence on magnetic fields in the ground. These variations in the magnetic field are also visible on seismometers, to the extent that during an auroral event, the long-period (40–800 s) waves recorded by a seismometer are magnetic field variations, not true ground motion. Although this is a problem—one that can be rectified with magnetic shielding at each seismometer site—it is also an opportunity because the present seismic array in Alaska is much broader than the coverage by magnetometers and all-sky cameras. Here we focus on three aurora events and document a direct link between aurora images in the night sky and seismometer recordings on ground. Simultaneous recordings by magnetometers provide a critical link between the sky images and the seismometer recordings. We document qualitative correlations among sky, magnetic, and seismic data. The findings suggest that the signature of auroral activity is widespread across seismometers in Alaska, implying that the seismic array could be used to enhance the spatial resolution of the existing network of all-sky cameras and magnetometers. Future efforts to improve the multisensor seismic stations in Alaska, for the purpose of monitoring seismic and auroral activity, should consider installation of all-sky cameras, installation of magnetometers, and magnetic shielding of seismic sensors.

scholarly journals The relative contributions of scattering and viscoelasticity to the attenuation of S waves in Earth's mantle

Solid Earth ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 161-171
Author(s):  
Susini deSilva ◽  
Vernon F. Cormier
Keyword(s):  
Dominant Frequency ◽  
Relative Strength ◽  
Density Fluctuations ◽  
Body Waves ◽  
Small Scale ◽  
Thermodynamic Models ◽  
S Waves ◽  
Intrinsic Attenuation ◽  
Apparent Attenuation ◽  
Deep Focus

Abstract. The relative contributions of scattering and viscoelastic attenuation to the apparent attenuation of seismic body waves are estimated from synthetic and observed S waves multiply reflected from Earth's surface and the core–mantle boundary. The synthetic seismograms include the effects of viscoelasticity and scattering from small-scale heterogeneity predicted from both global tomography and from thermodynamic models of mantle heterogeneity that have been verified from amplitude coherence measurements of body waves observed at dense arrays. Assuming thermodynamic models provide an estimate of the maximum plausible power of heterogeneity measured by elastic velocity and density fluctuations, we predict a maximum scattering contribution of 43 % to the total measured attenuation of mantle S waves having a dominant frequency of 0.05 Hz. The contributions of scattering in the upper and lower mantle to the total apparent attenuation are estimated to be roughly equal. The relative strength of the coda surrounding observed ScSn waves from deep focus earthquakes is not consistent with a mantle having zero intrinsic attenuation.

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