scholarly journals Integrated Offshore Seismic Survey Using an Unmanned Wave Glider

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 297
Author(s):  
Snons Cheong ◽  
Young-Jun Kim ◽  
Jong-Hwa Chun ◽  
Jung-Ki Kim ◽  
Shin Huh
Keyword(s):  
Single Channel ◽  
Seismic Refraction ◽  
Seismic Source ◽  
Offshore Structures ◽  
Seismic Survey ◽  
Acoustic Basement ◽  
Sedimentary Deposits ◽  
Reflection Data ◽  
Autonomous Surface Vehicle ◽  
Wave Glider

An autonomous surface vehicle, known as a wave glider, was used to record refracted and reflected signals from a seismic source penetrating the shallow subsurface. An integrated survey system consisting of a wave gilder and a human-operated source vessel was deployed. These survey systems are used to acquire wide-offset seismic survey data from specific areas, such as offshore structures. The wave gliders can collect seismic refraction and reflection data, which can be used to estimate subsurface information, e.g., acoustic wave velocity and subsurface structure. We processed raw data collected by a receiver equipped with the wave glider and used the relationship between travel time and offset distance to calculate the velocities of shallow sedimentary deposits and the acoustic basement. The velocities of the sedimentary deposits and basement were estimated to be 1557 and 3507 m/s, respectively. We then overlaid the velocities on subsurface data measured using a single-channel streamer. Our results indicate that unmanned equipment can be used for ocean exploration to aid offshore energy development.

Surface Seismic Measurements of Near-Surface P- and S-Wave Seismic Velocities at Earthquake Recording Stations, Seattle, Washington

1999 ◽  
Vol 15 (3) ◽  
pp. 565-584 ◽  
Author(s):  
Robert A. Williams ◽  
William J. Stephenson ◽  
Arthur D. Frankel ◽  
Jack K. Odum
Keyword(s):  
Seismic Refraction ◽  
Ground Surface ◽  
Industrial Area ◽  
High Amplitude ◽  
Seismic Velocities ◽  
S Wave ◽  
Near Surface ◽  
Sedimentary Deposits ◽  
Reflection Data ◽  
Seismic Reflections

We measured P- and S-wave seismic velocities to about 40-m depth using seismic-refraction/reflection data on the ground surface at 13 sites in the Seattle, Washington, urban area, where portable digital seismographs recently recorded earthquakes. Sites with the lowest measured Vs correlate with highest ground motion amplification. These sites, such as at Harbor Island and in the Duwamish River industrial area (DRIA) south of the Kingdome, have an average Vs in the upper 30 m (V¯s30) of 150 to 170 m/s. These values of V¯s30 place these sites in soil profile type E (V¯s30 < 180 m/s). A “rock” site, located at Seward Park on Tertiary sedimentary deposits, has a V¯s30 of 433 m/s, which is soil type C (V¯s30: 360 to 760 m/s). The Seward Park site V¯s30 is about equal to, or up to 200 m/s slower than sites that were located on till or glacial outwash. High-amplitude P- and S-wave seismic reflections at several locations appear to correspond to strong resonances observed in earthquake spectra. An S-wave reflector at the Kingdome at about 17 to 22 m depth probably causes strong 2-Hz resonance that is observed in the earthquake data near the Kingdome.

A comparative study of multi-scaled high-resolution seismic surveys in shallow marine environments: examples from three sites, offshore Korea

2020 ◽  
Author(s):  
Young Jun Kim ◽  
Snons Cheong ◽  
Deniz Cukur ◽  
Dong-Geun Yoo
Keyword(s):  
High Resolution ◽  
Data Processing ◽  
Seismic Data ◽  
Single Channel ◽  
Seismic Source ◽  
Seismic Survey ◽  
Minimum Length ◽  
Seismic Surveys ◽  
Air Gun ◽  
Target Depth

&lt;p&gt;In marine seismic surveys, various acquisition systems are used depending on the survey purpose, target depth, survey environment, and conditions. A 3D survey of oil and/or gas exploration, for instance, require large-capacity air-gun arrays and six or more streamers with a minimum length of 6 km. In contrast, a high-resolution seismic survey for the shallow-water geological research and engineering needs a small capacity source such as air-gun, sparker, and boomer, deployed with a single-channel or multi-channel (24-channel) streamers. The main purpose of our seismic survey was to investigate the Quaternary geology and stratigraphy of offshore, Korea. Because the Quaternary is the most recent geological period, our target depth was very shallow at about 50 m below the sea-bottom. We used a high-frequency seismic source including a sparker of 2,000 J capacity or a 60 in&lt;sup&gt;3&lt;/sup&gt; mini GI-gun and an eight-channel streamer with a 3.125 m group interval or a single-channel streamer that included 96 elements. To compare the resolution of seismic data according to the seismic source, a boomer or sparker systems were used with the single-channel streamer on a small survey ship. The seismic data processing was performed at the Korea Institute of Geoscience and Mineral Resources (KIGAM) with ProMAX, and the data processing and resolution of each survey were compared based on their acquisition systems.&lt;/p&gt;

Structural interpretation using refraction velocities from marine seismic surveys

Geophysics ◽  
1986 ◽  
Vol 51 (1) ◽  
pp. 12-19 ◽  
Author(s):  
James F. Mitchell ◽  
Richard J. Bolander
Keyword(s):  
Sedimentary Rock ◽  
Seismic Energy ◽  
Seismic Survey ◽  
Subsurface Structure ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
Reflection Data ◽  
Wide Range ◽  
Streamer Length ◽  
Set Up

Subsurface structure can be mapped using refraction information from marine multichannel seismic data. The method uses velocities and thicknesses of shallow sedimentary rock layers computed from refraction first arrivals recorded along the streamer. A two‐step exploration scheme is described which can be set up on a personal computer and used routinely in any office. It is straightforward and requires only a basic understanding of refraction principles. Two case histories from offshore Peru exploration demonstrate the scheme. The basic scheme is: step (1) shallow sedimentary rock velocities are computed and mapped over an area. Step (2) structure is interpreted from the contoured velocity patterns. Structural highs, for instance, exhibit relatively high velocities, “retained” by buried, compacted, sedimentary rocks that are uplifted to the near‐surface. This method requires that subsurface structure be relatively shallow because the refracted waves probe to depths of one hundred to over one thousand meters, depending upon the seismic energy source, streamer length, and the subsurface velocity distribution. With this one requirement met, we used the refraction method over a wide range of sedimentary rock velocities, water depths, and seismic survey types. The method is particularly valuable because it works well in areas with poor seismic reflection data.

Effects of near-surface waveguides on shallow high-resolution seismic refraction and reflection data

1996 ◽  
Vol 23 (5) ◽  
pp. 495-498 ◽  
Author(s):  
J. O. A. Robertsson ◽  
K. Holliger ◽  
A. G. Green ◽  
A. Pugin ◽  
R. De Iaco
Keyword(s):  
High Resolution ◽  
Seismic Refraction ◽  
Near Surface ◽  
Reflection Data

Far-offset detection of normal modes and diving waves: a case study in Valhall, southern North Sea

Geophysics ◽  
2021 ◽  
pp. 1-50
Author(s):  
Filipe Borges ◽  
Martin Landrø
Keyword(s):  
Normal Modes ◽  
Seismic Source ◽  
Velocity Model ◽  
Seismic Survey ◽  
The Past ◽  
Lack Of Control ◽  
Record Data ◽  
Refracted Waves ◽  
1D Velocity Model

The use of permanent arrays for continuous reservoir monitoring has become a reality in the past decades, with Ekofisk and Valhall being its flagships. One of the possibilities when such solution is available is to passively record data while acquisitions with an active source are ongoing in nearby areas. These recordings might contain ultrafar-offset data (over 30 km), which are hardly used in standard reservoir exploration and monitoring, as they are mostly a combination of normal modes, deep reflections and diving waves. We present here data from the Valhall Life of Field Seismic array, recorded while an active seismic survey was being acquired in Ekofisk, in April 2014. Despite the lack of control on source firing time and position, analysis of the data shows that the normal modes are remarkably clear, overcoming the ambient noise in the field. The normal modes can be well explained by a two-layer acoustic model, while a combination of diving waves and refracted waves can be fairly well reproduced with a regional 1D velocity model. We suggest a method to use the far-offset recordings to monitor changes in the shallow sediments between source and receivers, both with and without a coherent seismic source in the area.

Lithospheric structure in northwestern Canada from Lithoprobe seismic refraction and related studies: a synthesis

2005 ◽  
Vol 42 (6) ◽  
pp. 1277-1293 ◽  
Author(s):  
Ron M Clowes ◽  
Philip TC Hammer ◽  
Gabriela Fernández-Viejo ◽  
J Kim Welford
Keyword(s):  
Seismic Data ◽  
Seismic Refraction ◽  
Velocity Model ◽  
Wide Angle ◽  
Slave Craton ◽  
Reflection Data ◽  
Western Cordillera ◽  
Thermal Constraints ◽  
Geological Information ◽  
Tectonic Boundaries

The SNORCLE refraction – wide-angle reflection (R/WAR) experiment, SNORE'97, included four individual lines along the three transect corridors. A combination of SNORE'97 results with those from earlier studies permits generation of a 2000 km long lithospheric velocity model that extends from the Archean Slave craton to the present Pacific basin. Using this model and coincident near-vertical incidence (NVI) reflection data and geological information, an interpreted cross section that exemplifies 4 Ga of lithospheric development is generated. The velocity structural models correlate well with the reflection sections and provide additional structural, compositional, and thermal constraints. Geological structures and some faults are defined in the upper crust. At a larger scale, the seismic data identify a variety of orogenic styles ranging from thin- to thick-skinned accretion in the Cordillera and crustal-scale tectonic wedging associated with both Paleoproterozoic and Mesozoic collisions. Models of Poisson's ratio support the NVI interpretation that a thick wedge of cratonic metasediments underlies the eastern accreted Cordilleran terranes. Despite the variety of ages, orogenic styles, and tectono-magmatic deformations that are spanned by the seismic corridors, the Moho remains remarkably flat and shallow (33–36 km) across the majority of the transect. Significant variations only occur at major tectonic boundaries. Laterally variable crustal velocities are consistently slower beneath the Cordillera than beneath the cratonic crust. This is consistent with the high temperatures (800–900 °C) required by the slow upper mantle velocities (7.8–7.9 km/s) observed beneath much of the Cordillera. Heterogeneity of the lithospheric mantle is indicated by wide-angle reflections below the Precambrian domains and the western Cordillera.

Research on Position Keeping and Path Following Strategy for the Under-Actuated Waved Glider

2020 ◽  
Author(s):  
Peng Wang ◽  
Xinliang Tian ◽  
Xiantao Zhang ◽  
Daoyong Wang ◽  
Xiaoxian Guo
Keyword(s):  
Mathematical Model ◽  
Surface Waves ◽  
Path Following ◽  
Degree Of Freedom ◽  
Environmental Disturbances ◽  
Autonomous Surface Vehicle ◽  
Wave Glider

Abstract Wave glider is a novel autonomous surface vehicle that uses energy from surface waves for propulsion. However, because it is inherently under-actuated, multi-variable and strong coupled, it is challenging to control the wave glider accurately under the environmental disturbances. In this study, a novel robust position keeping guidance strategy and an advanced path following approach for the under-actuated wave glider based on restricted circle are firstly developed. Furthermore, an 8-DOFs (Degree-of-Freedom) mathematical model for the under-actuated wave glider is adopted, and the position keeping and path following tasks of the wave glider are conducted in simulation. The results demonstrate that the under-actuated wave glider is able to accomplish the position keeping and path following tasks with the proposed strategies.

scholarly journals Seismic reflection imaging of a geothermal aquifer in an urban setting

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1285-1294 ◽  
Author(s):  
Lee Liberty
Keyword(s):  
Seismic Reflection ◽  
Seismic Source ◽  
Urban Setting ◽  
Seismic Survey ◽  
Quality Data ◽  
Signal Quality ◽  
Fracture Permeability ◽  
Air Gun ◽  
Explosive Source ◽  
Geothermal Aquifer

A seismic reflection survey that was conducted in downtown Boise, Idaho, to help city planners site a new well for injection of spent geothermal water illustrates some methods to safely and successfully employ a seismic reflection survey in an urban setting. The objective of the seismic survey was to estimate the depth and continuity of a basalt and rhyolite volcanic sequence. Well siting was based on geothermal aquifer depth, location of interpreted faults, projected thermal impact of injection on existing wells, surface pipe extension costs, and public land availability. Seismic acquisition tests and careful processing were used to ensure high‐quality data while minimizing the potential for damage along city streets. A video camera placed in a sewer and a blast vibration monitor were used to confirm that energy from the seismic source (a 75-in3 land air gun) did not damage nearby buildings, street surfaces, or buried utilities along the survey lines. Walkaway seismic tests were also used to compare signal quality of the air‐gun source to an explosive source for imaging targets up to 800 m depth. These tests show less signal bandwidth from the air‐gun source compared to the buried explosive source, but the air‐gun signal quality was adequate to meet imaging objectives. Seismic reflection results show that the top of this rhyolite/basalt sequence dips (∼8–11°) southwest away from the Boise foothills at depths of 200 to 800 m. Seismic methods enabled interpretation of aquifer depths along the profiles and located fault zones where injected water may encounter fracture permeability and optimally benefit the existing producing system. The acquisition and processing techniques used to locate the Boise injection well may succeed for other hydrogeologic and environmental studies in urban settings.

Wide-area imaging from OBS multiples

Geophysics ◽  
2009 ◽  
Vol 74 (6) ◽  
pp. Q41-Q47 ◽  
Author(s):  
Ranjan Dash ◽  
George Spence ◽  
Roy Hyndman ◽  
Sergio Grion ◽  
Yi Wang ◽  
...  
Keyword(s):  
Single Channel ◽  
Water Layer ◽  
Velocity Model ◽  
Imaging Method ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Conventional Imaging ◽  
Depth Migration ◽  
Reflection Data ◽  
Obs Data

The subseafloor structure offshore western Canada was imaged using first-order water-layer multiples from ocean-bottom seismometer (OBS) data and the results were compared to conventional imaging using primary reflections. This multiple-migration (mirror-imaging) method uses the downgoing pressure wavefield just above the seafloor, which is devoid of any primary reflections but consists of receiver-side ghosts of these primary reflections. The mirror-imaging method employs a primaries-only Kirchhoff prestack depth migration algorithm to image the receiver ghosts. The additional travel path of the multiples through the water layer is accounted for by a simple manipulation of the velocity model and processing datum: the receivers lie not on the seabed but on a sea surface twice as high as the true water column. Migration results show that the multiple-migrated image provides a much broader illumination of the subsurface than is possible for conventional imaging using the primaries, especially for the very shallow reflections and sparse OBS spacing. The resulting image from mirror imaging has illumination comparable to the vertical incidence surface streamer (single-channel) reflection data.

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