Conventional multichannel surveys provide good images in 2D and 3D of the Earth in depth, which are successfully used for the oil and gas industries. However, their cost and environmental impact make them rarely affordable for engineering applications, especially for offshore infrastructures. In this case, monochannel systems, such as Boomers, having cables that are a few-meters long, provide time-domain images that are useful but miss relevant lithological information for engineers, such as the P-wave velocity of shallow layers. In this paper, we present a tomographic approach that exploits multiple reflections, in addition to primaries and direct arrivals, which work for monochannel surveys with a short offset. It can detect lateral variations of velocity and thickness of the first layer under the sea floor. Two complementary algorithms are compared: a pure tomographic inversion, and a tuning exploiting the classical Dix formula; the first one is more precise, while the second is more robust with respect to noise. A two-step inversion with incidence-angle parametrization performs slightly better than a single-step algorithm based on the direct traveltime inversion. We validate the method by synthetic and real data examples.

Tomographic Joint Inversion of Direct Arrivals, Primaries and Multiples for Monochannel Marine Surveys

Vesnaver A.
;
Baradello L.
2022-01-01

Abstract

Conventional multichannel surveys provide good images in 2D and 3D of the Earth in depth, which are successfully used for the oil and gas industries. However, their cost and environmental impact make them rarely affordable for engineering applications, especially for offshore infrastructures. In this case, monochannel systems, such as Boomers, having cables that are a few-meters long, provide time-domain images that are useful but miss relevant lithological information for engineers, such as the P-wave velocity of shallow layers. In this paper, we present a tomographic approach that exploits multiple reflections, in addition to primaries and direct arrivals, which work for monochannel surveys with a short offset. It can detect lateral variations of velocity and thickness of the first layer under the sea floor. Two complementary algorithms are compared: a pure tomographic inversion, and a tuning exploiting the classical Dix formula; the first one is more precise, while the second is more robust with respect to noise. A two-step inversion with incidence-angle parametrization performs slightly better than a single-step algorithm based on the direct traveltime inversion. We validate the method by synthetic and real data examples.
2022
Boomer
joint inversion
multiple reflections
offshore engineering
P velocity
seafloor characterization
seismic imaging
tomography
File in questo prodotto:
File Dimensione Formato  
geosciences-12-00219.pdf

accesso aperto

Tipologia: Versione Editoriale (PDF)
Licenza: Copyright dell'editore
Dimensione 6.13 MB
Formato Adobe PDF
6.13 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14083/18564
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 3
  • ???jsp.display-item.citation.isi??? 3
social impact