Title: The character and amplitude of ‘discontinuous’ bottom-simulating reflections in marine seismic data

Abstract

Bottom-simulating reflections (BSRs) identified in seismic data are well documented; and are commonly interpreted to indicate the presence of gas hydrates along continental margins, as well as to estimate regional volumes of gas hydrate. A BSR is defined as a reflection that sub-parallels the seafloor but is opposite in polarity and cross-cuts dipping sedimentary strata. BSRs form as a result of a strong negative acoustic impedance contrast. BSRs, however, are a diverse seismic phenomena that manifest in strikingly contrasting ways in different geological settings, and in different seismic data types. We investigate the characteristics of BSRs, using conventional and high resolution, 2D and 3D seismic data sets in three locations: the Terrebonne and Orca Basins in the Gulf of Mexico, and Blake Ridge on the US Atlantic Margin. The acquisition geometry and frequency content of the seismic data significantly impact the resultant character of BSRs, as observed with depth and amplitude maps of the BSRs. Furthermore, our amplitude maps reinforce the concept that the BSR represents a zone, over which the transition from hydrate to free gas occurs, as opposed to the conventional model of the BSR occurring at a single interface. Our results show that a BSR can bemore » mapped in three dimensions but it is not spatially continuous, at least not at the basin scale. Rather, a BSR manifests itself as a discontinuous, or patchy, reflection and only at local scales is it continuous. We suggest the discontinuous nature of BSRs is the result of variable saturation and distribution of free gas and hydrate, acquisition geometry and frequency content of the recorded seismic data. Lastly, the commonly accepted definition of a BSR should be broadened with careful consideration of these factors, to represent the uppermost extent of enhanced amplitude at the shallowest occurrence of free gas trapped by overlying hydrate-bearing sediments.« less

Authors:

Hillman, Jess I. T. ^[1]; Cook, Ann E.  ^[1];

• Search DOE PAGES for author "Cook, Ann E."
• Search DOE PAGES for ORCID "0000-0002-5658-0329"

Sawyer, Derek E. ^[1]; Kucuk, H. Mert  ^[2];

• Search DOE PAGES for author "Kucuk, H. Mert"
• Search DOE PAGES for ORCID "0000-0003-1822-8129"

Goldberg, David S. ^[3]

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+ Show Author Affiliations

1. The Ohio State Univ., Columbus, OH (United States)
2. Dokuz Eylul Univ., Izmir (Turkey); Lamont-Doherty Earth Observatory, Palisades, NY (United States)
3. Lamont-Doherty Earth Observatory, Palisades, NY (United States)

Publication Date:

Tue Nov 22 00:00:00 EST 2016

Research Org.:

The Ohio State Univ., Columbus, OH (United States); Univ. of Texas, Austin, TX (United States); Lamont-Doherty Earth Observatory, Palisades, NY (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE)

OSTI Identifier:

1373262

Alternate Identifier(s):

OSTI ID: 1398697

Grant/Contract Number:  

FE0023919

Resource Type:

Accepted Manuscript

Journal Name:

Earth and Planetary Science Letters

Additional Journal Information:

Journal Volume: 459; Journal Issue: C; Journal ID: ISSN 0012-821X

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

03 NATURAL GAS; 58 GEOSCIENCES; BSR; gas hydrate; seismic frequency content; resolution