Methodology for dense spatial sampling of multicomponent recording of converted waves in shallow marine environments

Allouche, Nihed; Drijkoningen, G.G.; Neut, Joost van der

doi:10.1190/1.3481362

Cited by 3 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…() and some limited mode‐converted wave analysis (Bohlen et al . ; Allouche, Drijkoningen and van der Neut ; Allouche et al . ; Drijkoningen et al .…”

Section: Characterization Of Sedimentsunclassified

“…Over the following sections, each of these parameters is considered in turn using a range of different example datasets However, a major limitation with the quantitative methods applied to the marine shallow subsurface is that S-waves or surface waves are only rarely considered. Notable exceptions are the multi-model surface wave inversion work of Socco et al (2011) and Vanneste et al (2011) and some limited mode-converted wave analysis (Bohlen et al 2004;Allouche, Drijkoningen and van der Neut 2010;Allouche et al 2011;Drijkoningen et al 2012). As S-waves are transmitted through the grain skeleton, they provide a more direct link between the geotechnical and geomechanical parameters than P-waves.…”

Section: Stress Regimementioning

confidence: 99%

See 1 more Smart Citation

State‐of‐the‐art remote characterization of shallow marine sediments: the road to a fully integrated solution

Vardy

Vanneste

Henstock

et al. 2017

Near Surface Geophysics

View full text Add to dashboard Cite

Current methods for characterizing near‐surface marine sediments rely on extensive coring/pene‐trometer testing and correlation to seismic facies. Little quantitative information is regularly derived from geophysical data beyond qualitative inferences of sediment characteristics based on seismic facies architecture. Even these fundamental seismostratigraphic interpretations can be difficult to correlate with lithostratigraphic data due to inaccuracies in the time‐to‐depth conversion of geophysical data and potential loss and/or compression of high‐porosity and under‐consolidated sea‐floor material during direct sampling. To complicate matters further, when quantitative information is derived from marine geophysical data, it often describes the sediments using terminology (e.g., acoustic impedance and seismic quality factor) that is impenetrable to geologists and engineers. In contrast, for hydrocarbon prospecting, reservoir characterization using quantitative inversion of geophysical data has developed enormously over the past 20 years or more. Impedance and amplitude‐versus‐angle inversion techniques are now commonplace, whereas computationally expensive waveform inversions are gaining traction, and there is a well‐developed interface between these geophysical and reservoir engineering fields via rock physics. In this paper, we collate and review the different published inversion methods for high‐resolution geophysical data. Using several case study examples spanning a broad range of depositional environments, we assess the current state of the art in remote characterization of shallow sediments from a multidisciplinary viewpoint, encompassing geophysical, geological, and geotechnical angles. By identifying the key parameters used to characterize the subsurface, a framework is developed whereby geological, geotechnical, and geophysical characterizations of the subsurface can be related in a less subjective manner. As part of this, we examine the sensitivity of commonly derived acoustic properties (e.g., acoustic impedance and seismic quality factor) to more fundamentally important soil properties (e.g., lithology, pore pressure, gas saturation, and undrained shear strength), thereby facilitating better integration between geological, geotechnical, and geophysical data for improved mapping of sediment properties. Ultimately, we present a number of ideas for future research activities in this field.

show abstract

“…() and some limited mode‐converted wave analysis (Bohlen et al . ; Allouche, Drijkoningen and van der Neut ; Allouche et al . ; Drijkoningen et al .…”

Section: Characterization Of Sedimentsunclassified

Section: Stress Regimementioning

confidence: 99%

State‐of‐the‐art remote characterization of shallow marine sediments: the road to a fully integrated solution

Vardy

Vanneste

Henstock

et al. 2017

Near Surface Geophysics

View full text Add to dashboard Cite

show abstract

“…This had been observed on the OBC as well (Allouche et al, 2010), which was initially interpreted as bad coupling, but the borehole sensors are well-coupled to the borehole wall, so the noise was therefore interpreted as generated by the river flow (∼3 m∕s). The main arrivals are the direct P-waves with a velocity of ∼1600 m∕s and the Scholte-wave with a velocity of 240 m∕s.…”

Section: Borehole Datamentioning

confidence: 99%

“…Recently, Allouche et al (2010Allouche et al ( , 2011 have shown that these nongeometrically converted shear waves are clearly observable in data from a marine environment. They used data from water-bottom receivers in a shallow canal to demonstrate this statement, and they modeled seismic data to verify whether the observed response was consistent with the simulated response.…”

Section: Introductionmentioning

confidence: 99%

Nongeometrically converted shear waves in marine streamer data

et al. 2012

View full text Add to dashboard Cite

Under certain circumstances, marine streamer data contain nongeometrical shear body wave arrivals that can be used for imaging. These shear waves are generated via an evanescent compressional wave in the water and convert to propagating shear waves at the water bottom. They are called "nongeometrical" because the evanescent part in the water does not satisfy Snell's law for real angles, but only for complex angles. The propagating shear waves then undergo reflection and refraction in the subsurface, and arrive at the receivers via an evanescent compressional wave. The required circumstances are that sources and receivers are near the water bottom, irrespective of the total water depth, and that the shear-wave velocity of the water bottom is smaller than the P-wave velocity in the water, most often the normal situation. This claim has been tested during a seismic experiment in the river Danube, south of Budapest, Hungary. To show that the shear-related arrivals are body rather than surface waves, a borehole was drilled and used for multicomponent recordings. The streamer data indeed show evidence of shear waves propagating as body waves, and the borehole data confirm that these arrivals are refracted shear waves. To illustrate the effect, finite-difference modeling has been performed and it confirmed the presence of such shear waves. The streamer data were subsequently processed to obtain a shear-wave refraction section; this was obtained by removing the Scholte wave arrival, separating the wavefield into different refracted arrivals, stacking and depth-converting each refracted arrival before adding the different depth sections together. The obtained section can be compared directly with the standard P-wave reflection section. The comparison shows that this approach can deliver refracted-shear-wave sections from streamer data in an efficient manner, because neither the source nor receivers need to be situated on the water bottom.

show abstract

Separation of PS-wave Reflections from Ultra-shallow Water OBC Data Using Elastic Wavefield Decomposition

Allouche¹,

Neut²,

Drijkoningen³

2013

London 2013, 75th Eage Conference en Exhibition Incorporating SPE Europec

View full text Add to dashboard Cite

SUMMARYElastic wave decomposition, aiming at separating the converted modes from the P-waves, is applied to high-resolution OBC data acquired in the River Danube, Hungary. The decomposition relies on accurate knowledge of the water-bottom elastic parameters and on a perfect sensor calibration and coupling. The available decomposition schemes require an adaptation to account for the shallow water depth in the survey area. In the presented method, the medium parameters are obtained from the inversion of the Scholte waves dispersion curves and the coupling filter was determined from the data. The coupling filter accounts for the imperfections in the geophone coupling and was corrected for by minimizing the contribution of the pressure and vertical component to the upgoing S-wave potential at near offsets. This criterion implies that these two components contain no converted energy at these offsets. The estimated coupling filter is applied to the geophone data used as an input to the decomposition scheme. The decomposed S-wave potential showed an improvement in the visibility of some converted modes, mainly at later arrivals.

show abstract

Methodology for dense spatial sampling of multicomponent recording of converted waves in shallow marine environments

Cited by 3 publications

References 15 publications

State‐of‐the‐art remote characterization of shallow marine sediments: the road to a fully integrated solution

State‐of‐the‐art remote characterization of shallow marine sediments: the road to a fully integrated solution

Nongeometrically converted shear waves in marine streamer data

Separation of PS-wave Reflections from Ultra-shallow Water OBC Data Using Elastic Wavefield Decomposition

Contact Info

Product

Resources

About