scholarly journals Geoacoustic Estimation of the Seafloor Sound Speed Profile in Deep Passive Margin Setting Using Standard Multichannel Seismic Data

2021 ◽  
Vol 9 (12) ◽  
pp. 1423
Author(s):  
Ernst Uzhansky ◽  
Omri Gadol ◽  
Guy Lang ◽  
Boris Katsnelson ◽  
Shelly Copel ◽  
...  
Keyword(s):  
Deep Water ◽  
Seismic Data ◽  
Sound Speed ◽  
Sound Propagation ◽  
Passive Margin ◽  
Seismic Profiles ◽  
Geoacoustic Inversion ◽  
Margin Setting ◽  
Receiver Array ◽  
Head Waves

Seafloor geoacoustic properties are important in determining sound propagation in the marine environment, which broadly affects sub-sea activities. However, geoacoustic investigation of the deep seafloor, which is required by the recent expansion of deep-water operations, is challenging. This paper presents a methodology for estimating the seafloor sound speed, c0, and a sub-bottom velocity gradient, K, in a relatively deep-water-compacting (~1000 m) passive-margin setting, based on standard commercial 2D seismic data. Here we study the seafloor of the southeastern Mediterranean margin based on data from three commercial seismic profiles, which were acquired using a 7.2 km-long horizontal receiver array. The estimation applies a geoacoustic inversion of the wide-angle reflections and the travel times of the head waves of bending rays. Under the assumption of a constant positive K, the geoacoustic inversion converges to a unique set of parameters that best satisfy the data. The analysis of 24 measurement locations revealed an increase in the average estimates of c0 from 1537 ± 13 m s−1 to 1613 ± 12 m s−1 for seafloor depths between ~1150 m and ~1350 m. K ranged between 0.75 and 0.85 m s−1 with an average of 0.80 ± 0.035 s−1. The parameters were consistent across the different locations and seismic lines and they match the values that were obtained through depth-migration-velocity analysis and empiric relations, thereby validating our estimation methodology.

Comparison of Sound Propagation Characteristic between Deep and Shallow Water

2014 ◽  
Vol 577 ◽  
pp. 1198-1201
Author(s):  
Zhang Liang ◽  
Chun Xia Meng ◽  
Hai Tao Xiao
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Sound Speed ◽  
Sound Propagation ◽  
Spherical Wave ◽  
Sound Field ◽  
Propagation Loss ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Propagation Law

The physical characteristics are compared between shallow and deep water, in physics and acoustics, respectively. There is a specific sound speed profile in deep water, which is different from which in shallow water, resulting in different sound propagation law between them. In this paper, the sound field distributions are simulated under respective typical sound speed profile. The color figures of sound intensity are obtained, in which the horizontal ordinate is distance, and the vertical ordinate is depth. Then we can get some important characteristics of sound propagation. The results show that the seabed boundary is an important influence on sound propagation in shallow water, and sound propagation loss in deep water convergent zone is visibly less than which in spherical wave spreading. We can realize the remote probing using the acoustic phenomenon.

scholarly journals Egypt in the Twenty-First Century: Petroleum Potential in Offshore Trends

GeoArabia ◽  
2001 ◽  
Vol 6 (2) ◽  
pp. 211-230 ◽  
Author(s):  
John C. Dolson ◽  
Mark V. Shann ◽  
Sayed I. Matbouly ◽  
Hussein Hammouda ◽  
Rashed M. Rashed
Keyword(s):  
Red Sea ◽  
Deep Water ◽  
Seismic Data ◽  
Passive Margin ◽  
Source Rocks ◽  
Western Desert ◽  
Field Size ◽  
Gulf Of Aqaba ◽  
Gulf Of Suez ◽  
Complete Replacement

ABSTRACT Since the onshore discovery of oil in the Eastern Desert in 1886, the petroleum industry in Egypt has accumulated reserves of more than 15.5 billion barrels of oil equivalent. An understanding of the tectono-stratigraphic history of each major basin, combined with drilling history and field-size distributions, justifies the realization of the complete replacement of these reserves in the coming decades. Most of the increase in reserves will be the result of offshore exploration. In addition to the 25 trillion cubic feet already discovered, the offshore Mediterranean may hold 64 to 84 trillion cubic feet and the onshore Western Desert may contribute 15 to 30 trillion cubic feet in new gas resources. Many of the new fields are expected to be in the giant-field class that contains greater than 100 million barrels of oil equivalent. Challenges include sub-salt imaging, market constraints for predominantly gas resources and economic constraints imposed by the high cost of development of the current deep-water gas discoveries that are probably unique worldwide. The offshore Gulf of Suez may yield an additional 1.5 to 3.3 billion barrels of oil equivalent, but it continues to be technologically constrained by poor-quality seismic data. Advances in multiple suppression and development of new ‘off-structure’ play concepts with higher quality seismic data should result in continual new pool discoveries. Offshore frontier exploration includes the Red Sea rift (currently under reassessment with area-wide 3-D surveys) and the Gulf of Aqaba. Deep-water and sub-salt imaging remain significant challenges to be overcome. Despite a relatively complex history, the Phanerozoic geological framework of Egypt is extremely prospective for oil and gas. Eight major tectono-stratigraphic events are: (1) Paleozoic craton; (2) Jurassic rifting; (3) Cretaceous passive margin; (4) Cretaceous Syrian Arc deformation and foreland transgressions; (5) Oligocene-Miocene Gulf of Suez rifting; (6) Miocene Red Sea opening; (7) the Messinian salinity crisis; and (8) Pliocene-Pleistocene delta progradation. Each of these events has created multiple reservoir and seal combinations. Source rocks occur from the Paleozoic through to the Pliocene and petroleum is produced from reservoirs that range in age from Precambrian to Pleistocene. The offshore Mediterranean, Gulf of Suez and Red Sea/Gulf of Aqaba contain significant exploration potential and will provide substantial reserve replacements in the coming decades.

scholarly journals Using a kilometers-long horizontal multichannel array for estimating seafloor sound speed in a passive margin setting

2021 ◽  
Author(s):  
Ernst Uzhansky ◽  
Omri Gadol ◽  
Guy Lang ◽  
Boris Katsnelson ◽  
Shelly Copel ◽  
...  
Keyword(s):  
Sound Speed ◽  
Passive Margin ◽  
Margin Setting

scholarly journals Multi-Proxy Provenance Analyses of the Kingriali and Datta Formations (Triassic—Jurassic Transition): Evidence for Westward Extension of the Neo-Tethys Passive Margin from the Salt Range (Pakistan)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 573
Author(s):  
Shahid Iqbal ◽  
Michael Wagreich ◽  
Mehwish Bibi ◽  
Irfan U. Jan ◽  
Susanne Gier
Keyword(s):  
Lower Jurassic ◽  
Sediment Supply ◽  
Heavy Mineral ◽  
Passive Margin ◽  
Indian Plate ◽  
Late Triassic ◽  
Indian Shield ◽  
Margin Setting ◽  
Salt Range ◽  
Mineral Data

The Salt Range, in Pakistan, preserves an insightful sedimentary record of passive margin dynamics along the NW margin of the Indian Plate during the Mesozoic. This study develops provenance analyses of the Upper Triassic (Kingriali Formation) to Lower Jurassic (Datta Formation) siliciclastics from the Salt and Trans Indus ranges based on outcrop analysis, petrography, bulk sediment elemental geochemistry, and heavy-mineral data. The sandstones are texturally and compositionally mature quartz arenites and the conglomerates are quartz rich oligomictic conglomerates. Geochemical proxies support sediment derivation from acidic sources and deposition under a passive margin setting. The transparent heavy mineral suite consists of zircon, tourmaline, and rutile (ZTR) with minor staurolite in the Triassic strata that diminishes in the Jurassic strata. Together, these data indicate that the sediments were supplied by erosion of the older siliciclastics of the eastern Salt Range and adjoining areas of the Indian Plate. The proportion of recycled component exceeds the previous literature estimates for direct sediment derivation from the Indian Shield. A possible increase in detritus supply from the Salt Range itself indicates notably different conditions of sediment generation, during the Triassic–Jurassic transition. The present results suggest that, during the Triassic–Jurassic transition in the Salt Range, direct sediment supply from the Indian Shield was probably reduced and the Triassic and older siliciclastics were exhumed on an elevated passive margin and reworked by a locally established fluvio-deltaic system. The sediment transport had a north-northwestward trend parallel to the northwestern Tethyan margin of the Indian Plate and normal to its opening axis. During the Late Triassic, hot and arid hot-house palaeoclimate prevailed in the area that gave way to a hot and humid greenhouse palaeoclimate across the Triassic–Jurassic Boundary. Sedimentological similarity between the Salt Range succession and the Neo-Tethyan succession exposed to the east on the northern Indian passive Neo-Tethyan margin suggests a possible westward extension of this margin.

scholarly journals Cluster Analysis of Deep Water Sound Speed Profiles in Indian Ocean

2019 ◽  
Vol 310 ◽  
pp. 052048
Author(s):  
Hua Wang ◽  
Yunbo Li ◽  
Qinghong Li ◽  
Xiangjun Yu
Keyword(s):  
Cluster Analysis ◽  
Indian Ocean ◽  
Deep Water ◽  
Sound Speed
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