How rough sea affects marine seismic data and deghosting procedures

Egorov, Anton; Glubokovskikh, Stanislav; Bóna, Andrej; Pevzner, Roman; Gurevich, Boris; Tokarev, M.

doi:10.1111/1365-2478.12535

Cited by 16 publications

(5 citation statements)

References 33 publications

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“…To introduce free‐surface reflections, we assume that the free surface is flat, and the reflectivity is −1. In practical marine acquisitions, the free surface can be complicated by the time‐varying fluctuant sea surface (Asgedom et al., 2017; Blacquière & Sertlek, 2019; Cecconello et al., 2018; Egorov et al., 2018; Laws & Kragh, 2002; Orji et al., 2013). Under this circumstance, the free‐surface reflectivity can be parameterized by effective coefficients which may be frequency dependent or frequency and angle dependent (Ainslie, 2010; Blacquière & Sertlek, 2019; Orji et al., 2013).…”

Section: Discussionmentioning

confidence: 99%

The effect of free‐surface reflections on depth images for acquisition with buried sources and receivers: Investigation through the point spread function#

Han

Xie

2023

Geophysical Prospecting

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In reverse time migration, if sources or receivers are buried at certain depths, the interference between the primary wave and the free‐surface reflection causes losing spectral contents in seismic data. If they are not properly compensated, errors will be carried to the target during the reverse time migration and cause a distorted image by so‐called ghost image. By invoking the point spread function, we investigate how distorted seismic data are mapped to the subsurface. Quantitative relations between the free‐surface parameters (i.e. source/receiver depth, free‐surface incident angle and near‐surface velocity) and wavenumber‐domain illumination can be created, which map missing frequency contents in seismic data to missing wavenumber contents in the point spread function. After transformed back to the space domain, we can investigate its effect on the image distortion. Numerical calculations expand the above approach to handle complex overburden structures and more realistic acquisition geometries. The proposed method provides us with a useful tool to investigate deghosting related problems, for example optimizing parameters of acquisition geometry, evaluating capabilities of existing acquisition systems and data processing technologies in suppressing the free‐surface reflection effect in the depth image, or developing new deghosting approaches.

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Section: Discussionmentioning

confidence: 99%

The effect of free‐surface reflections on depth images for acquisition with buried sources and receivers: Investigation through the point spread function#

Han

Xie

2023

Geophysical Prospecting

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“…Different from imaging of surface‐related multiples or internal multiples, it is difficult to image ghost reflections which follows primaries with extreme shot delay time and convert the primary wave into primary‐ghost wave. In real, the sea surface is rough in the marine seismic survey and makes ghost complicated (Egorov et al., 2018). Despite all this, ghost reflections can be used for sea surface imaging to improve the resolution of marine seismic data (Laws & Kragh, 2002; Orji et al., 2010).…”

Section: Introductionmentioning

confidence: 99%

Application of deconvolution interferometry to receiver ghost reflection in vertical cable seismic survey

Wang

Liu

et al. 2023

Geophysical Prospecting

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Marine vertical cable seismic is to probe targets near the submarine with use vertical hydrophone array suspending in deep sea water. Despite imaging of primary reflections from vertical cable seismic data can provide seismic profiles with high resolution, its submarine illumination is much narrower than that of conventional towed-streamer seismic owing to the irregular geometry. In view of the fact that imaging of multiples can provides better subsurface illumination with fine resolution, we present a strategy for imaging of receiver ghost reflections from vertical cable seismic data, based on seismic interferometry by deconvolution. This method can convert first-order receiver ghosts into virtual primaries from the towed-streamer data without velocity model and sourcereceiver position. We illustrate the deconvolution interferometry for the receiver ghost reflections with the real vertical cable seismic data in Shenhu area, South China Sea and further obtain virtual primary reflections. Finally, we use these virtual primaries to successfully construct a stacked image and obtain a post-stack migration image with conventional seismic data process method. This stacked and migrated image significantly extends the submarine illumination with higher resolution and it is useful in characteristics recognition of hydrate-bearing sediments and free gas.

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“…There is a wealth of literature discussing the modeling of the ghost and providing methods for deghosting. For example, Laws and Kragh (2002) use a Kirchhoff method for computing the ghost in the case of a rough sea surface and focus on the implications on time-lapse data; Mayhan and Weglein (2013) discuss source and receiver deghosting both inside and away from the notch areas using pressure as well as its vertical gradient (particle velocity); Amundsen and Zhou (2013) pay special attention to the low frequencies; Beasley et al (2013) and Robertsson et al (2014) use causality of the upcoming wavefield with respect to the downgoing wavefield in a deghosting method based on wave-equation modeling; Egorov et al (2018) study the effects of a rough sea surface for frequencies up to several kHz; Konuk and Shragge (2018) developed a mimetic finite-difference scheme using a dynamic mesh to compute the effects of the time-varying sea surface, and Cecconello et al (2018) derived an integral approach to modeling the time-variant reflection of a rough sea surface and who also provide an extensive literature review. In this paper, we introduce a modeling method where the source and/or the receiver ghost can be added to an existing ghost-free data set.…”

Section: Introductionmentioning

confidence: 99%

Modeling and assessing the effects of the sea surface, from being flat to being rough and dynamic

Blacquière

Sertlek

2019

GEOPHYSICS

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The sea surface acts as a very strong reflector because of the large impedance contrast between water and air. The reflection coefficient is [Formula: see text] in a very good approximation. Apart from the surface multiples, the sea surface is also responsible for generating the source and receiver ghost wavefields. These cause the well-known ghost notches in the spectrum: areas where the signal-to-noise ratio is very low. To model the ghost wavefields, ghost operators can be computed and applied to ghost-free data. Modeling experiments indicate that in the case of a flat sea surface, the character of the notches in various gather types, e.g., receiver gather, common-offset gather, shot record, is largely determined by the complexity of the earth. In a simple earth, e.g., horizontally layered, the notches are always well-defined and deep, but in a complex earth, they become blurry in some of the gather types. Therefore, in the case of a complex subsurface, source deghosting is best carried out in the common-receiver domain and receiver deghosting is best carried out in the common-shot domain. In the case of a simple subsurface, deghosting can be carried out in all domains. An additional factor is that the sea surface may be rough and dynamic. This causes blurry ghost notches in all gather types, even in the case of a simple earth. To model the source ghost for this situation, an effective static rough sea surface suffices. This keeps the computations simple. The condition is that the source has an impulsive character. However, to model the receiver ghost (and the source ghost for a nonimpulsive source), the dynamics of the sea surface must be included. This can be done by composing the final result from the results computed for several “frozen” snapshots of the dynamic sea surface.

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How rough sea affects marine seismic data and deghosting procedures

Cited by 16 publications

References 33 publications

The effect of free‐surface reflections on depth images for acquisition with buried sources and receivers: Investigation through the point spread function#

The effect of free‐surface reflections on depth images for acquisition with buried sources and receivers: Investigation through the point spread function#

Application of deconvolution interferometry to receiver ghost reflection in vertical cable seismic survey

Modeling and assessing the effects of the sea surface, from being flat to being rough and dynamic

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