P-Wave Ocean-Bottom Node Processing in Gulf of Mexico: a test survey

2015 ◽  
Author(s):  
Dwight V. Sukup ◽  
Patricia F. Crawford
Keyword(s):  
Gulf Of Mexico ◽  
P Wave ◽  
Ocean Bottom

Teepee technology applied to seismic acquisition P-wave design, Part 3: 3D ocean-bottom-cable example

2004 ◽  
Vol 23 (3) ◽  
pp. 214-217
Author(s):  
J. W. (Tom) Thomas ◽  
John M. Hufford ◽  
Gary M. Hoover ◽  
Warren H. Neff
Keyword(s):  
P Wave ◽  
Ocean Bottom ◽  
Seismic Acquisition

Multi-parameter model building for the Qiuyue structure using four-component ocean-bottom seismometer data

Geophysics ◽  
2021 ◽  
pp. 1-52
Author(s):  
Yuzhu Liu ◽  
Xinquan Huang ◽  
Jizhong Yang ◽  
Xueyi Liu ◽  
Bin Li ◽  
...  
Keyword(s):  
Wave Velocity ◽  
Waveform Inversion ◽  
Velocity Model ◽  
P Wave ◽  
Velocity Analysis ◽  
Full Waveform Inversion ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Full Waveform ◽  
P Wave Velocity

Thin sand-mud-coal interbedded layers and multiples caused by shallow water pose great challenges to conventional 3D multi-channel seismic techniques used to detect the deeply buried reservoirs in the Qiuyue field. In 2017, a dense ocean-bottom seismometer (OBS) acquisition program acquired a four-component dataset in East China Sea. To delineate the deep reservoir structures in the Qiuyue field, we applied a full-waveform inversion (FWI) workflow to this dense four-component OBS dataset. After preprocessing, including receiver geometry correction, moveout correction, component rotation, and energy transformation from 3D to 2D, a preconditioned first-arrival traveltime tomography based on an improved scattering integral algorithm is applied to construct an initial P-wave velocity model. To eliminate the influence of the wavelet estimation process, a convolutional-wavefield-based objective function for the preprocessed hydrophone component is used during acoustic FWI. By inverting the waveforms associated with early arrivals, a relatively high-resolution underground P-wave velocity model is obtained, with updates at 2.0 km and 4.7 km depth. Initial S-wave velocity and density models are then constructed based on their prior relationships to the P-wave velocity, accompanied by a reciprocal source-independent elastic full-waveform inversion to refine both velocity models. Compared to a traditional workflow, guided by stacking velocity analysis or migration velocity analysis, and using only the pressure component or other single-component, the workflow presented in this study represents a good approach for inverting the four-component OBS dataset to characterize sub-seafloor velocity structures.

Large-Scale, Shallow-Water, Ocean-Bottom Seismic Project in Southern Gulf of Mexico

2019 ◽  
Author(s):  
M. Ortin ◽  
M. Salgadoe ◽  
F. Fenoglio ◽  
A. Raj ◽  
M. Sanchez ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Shallow Water ◽  
Large Scale ◽  
Ocean Bottom ◽  
Southern Gulf Of Mexico

Performance of an Ocean Buoyancy Glider in a Coastal Region: Application to the Gulf of Mexico Hypoxic Zone

2017 ◽  
Vol 51 (4) ◽  
pp. 41-51
Author(s):  
Elizabeth Ramey ◽  
Steven F. DiMarco ◽  
Karen Dreger ◽  
Heather M. Zimmerle
Keyword(s):  
Gulf Of Mexico ◽  
Action Plan ◽  
Coastal Region ◽  
Ocean Bottom ◽  
Low Oxygen ◽  
Northern Gulf Of Mexico ◽  
Hypoxic Zone ◽  
Horizontal Stratification ◽  
Oxygen Conditions ◽  
Oil Gas

AbstractThe Gulf of Mexico Coastal Hypoxia Glider Experiment was designed to assess the feasibility of using ocean glider technology in the coastal hypoxic zone of the northern Gulf of Mexico in Summer/Fall 2014. The objectives were (1) to coordinate and operate multiple autonomous buoyancy ocean gliders in depths less than 50 m and (2) to determine how close to the bottom gliders can reliably reach without making contact. Strong vertical and horizontal stratification gradients, strong coastal currents, and the low-oxygen conditions that occur within the lower water column characterize the coastal area of the northern Gulf of Mexico. These environmental conditions combine with the presence of more than 5,000 surface piercing oil/gas structures to make piloting and navigation in the region challenging. We quantify glider performance to assess the usefulness of buoyancy gliders to address the National Oceanic and Atmospheric Administration Action Plan goal to monitor the spatial extent, duration, and severity of the Gulf hypoxic zone. We find that the gliders, despite the operational challenges, were consistently able to travel from the surface to the oxygen-depleted depths of subpycnocline waters, that is, within 2 m of the ocean bottom. Our assessment is that gliders are able to provide real-time observations suitable to monitor coastal hypoxia.

Case Study: A Large 3D Wide-Azimuth Ocean-Bottom Survey in the Deepwater Gulf of Mexico

2007 ◽  
Author(s):  
Richard Clarke ◽  
Ganyuan Xia ◽  
Nurul Kabir ◽  
Laurent Sirgue ◽  
Scott Michell
Keyword(s):  
Gulf Of Mexico ◽  
Ocean Bottom

In-Situ Calibration of Differential Pressure Gauges on OBSIP Ocean Bottom Seismometers

2020 ◽  
Author(s):  
Gabi Laske ◽  
Adrian Doran
Keyword(s):  
Pressure Sensor ◽  
Broad Band ◽  
Pressure Gauge ◽  
Differential Pressure ◽  
P Wave ◽  
Earth Tides ◽  
Release Mechanism ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer

<p>A standard ocean bottom seismometer (OBS) package of the U.S. OBS Instrument Pool (OBSIP) carries a seismometer and a pressure sensor. For broadband applications, the seismometer typically is a wide-band or broad-band three-components seismometer, and the pressure sensor is a differential pressure gauge (DPG). The purpose of the pressure sensor is manifold and includes the capture of pressure signals not picked up by a ground motion sensor (e.g. the passage of tsunami), but also for purposes of correcting the seismograms for unwanted signals generated in the water column (e.g. p-wave reverberations).<br>Unfortunately, the instrument response of the widely used Cox-Webb DPG remains somewhat poorly known, and can vary by individual sensor, and even by deployment of the same sensor.</p><p>Efforts have been under way to construct and test DPG responses in the laboratory. But the sensitivity and long‐period response are difficult to calibrate as they  vary with temperature and pressure, and perhaps by hardware of the same mechanical specifications.  Here, we present a way to test the response for each individual sensor and deployment in situ in the ocean. This test requires a relatively minimal and inexpensive modification to the OBS instrument frame and a release mechanism that allows a drop of the DPG by 3 inches after the OBS package settled and the DPG equilibrated on the seafloor. The seismic signal generated by this drop is then analyzed in the laboratory upon retrieval of the data. </p><p>The results compare favorably with calibrations estimated independently through post‐deployment data analyses of other signals such as Earth tides and the signals from large teleseismic earthquakes. Our study demonstrates that observed response functions can deviate from the nominal response by a factor of two or greater with regards to both the sensitivity and the time constant. Given the fact that sensor calibrations of DPGs in the lab require very specific and stable environments and are time consuming, the use of in-situ DPG calibration frames pose a reliable and inexpensive alternative. </p>

Evolution of Caribbean subduction from P-wave tomography and plate reconstruction

2020 ◽  
Author(s):  
Robert Allen ◽  
Benedikt Braszus ◽  
Saskia Goes ◽  
Andreas Rietbrock ◽  
Jenny Collier ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Plate Boundary ◽  
P Wave ◽  
Lesser Antilles ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Equatorial Atlantic ◽  
The North ◽  
The Caribbean ◽  
Plate Reconstruction

<p>The Caribbean plate has a complex tectonic history, which makes it  particularly challenging to establish the evolution of the subduction zones at its margins. Here we present a new teleseismic P-wave tomographic model under the Antillean arc that benefits from ocean-bottom seismometer data collected in our recent VoiLA (Volatile Recycling in the Lesser Antilles) project. We combine this imagery with a new plate reconstruction that we use to predict possible slab positions in the mantle today. We find that upper mantle anomalies below the eastern Caribbean correspond to a stack of material that was subducted at different trenches at different times, but ended up in a similar part of the mantle due to the large northwestward motion of the Americas. This stack comprises: in the mantle transition zone, slab fragments that were subducted between 70 and 55 Ma below the Cuban and Aves segments of the Greater Arc of the Caribbean; at 450-250 km depth, material subducted between 55 and 35 Ma below the older Lesser Antilles (including the Limestone Caribees and Virgin Islands);  and above 250 km, slab from subduction between 30 and 0 Ma below the present Lesser Antilles to Hispaniola Arc. Subdued high velocity anomalies in the slab above 200 km depth coincide with where the boundary between the equatorial Atlantic and proto-Caribbean subducted, rather than as previously proposed, with the North-South American plate boundary. The different phases of subduction can be linked to changes in the age, and hence buoyancy structure, of the subducting plate.</p>

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