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

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.

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Introduction to this special section: Acquisition and sensing

The Leading Edge ◽

10.1190/tle38090670.1 ◽

2019 ◽

Vol 38 (9) ◽

pp. 670-670

Author(s):

Margarita Corzo ◽

Tim Brice ◽

Ray Abma

Keyword(s):

Special Section ◽

Seismic Survey ◽

Ocean Bottom ◽

Total Cost ◽

Small Boat ◽

Air Gun ◽

Seismic Acquisition ◽

The Cost ◽

Seismic Images

Seismic acquisition has undergone a revolution over the last few decades. The volume of data acquired has increased exponentially, and the quality of seismic images obtained has improved tremendously. While the total cost of acquiring a seismic survey has increased, the cost per trace has dropped precipitously. Land surveys have evolved from sparse 2D lines acquired with a few dozen receivers to densely sampled 3D multiazimuth surveys. Marine surveys that once may have consisted of a small boat pulling a single cable have evolved to large streamer vessels pulling multiple cables and air-gun arrays and to ocean-bottom detectors that require significant fleets to place the detectors, shoot the sources, and provide support. These surveys collect data that are wide azimuth and typically fairly well sampled.

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NEW DIRECTIONS IN GEOSCIENCE TECHNOLOGY FOR PETROLEUM EXPLORATION IN THE NEW AGE

The APPEA Journal ◽

10.1071/aj93019 ◽

1994 ◽

Vol 34 (1) ◽

pp. 189

Author(s):

T. L. Burnett

Keyword(s):

Oil And Gas ◽

Regional Scale ◽

Seismic Energy ◽

Oil And Gas Industry ◽

Transport Processes ◽

Source Rocks ◽

P Wave ◽

Petroleum Exploration ◽

S Wave ◽

Seismic Acquisition

As economics of the oil and gas industry become more restrictive, the need for new means of improving exploration risks and reducing expenses is becoming more acute. Partnerships between industry and academia are making significant improvements in four general areas: Seismic acquisition, reservoir characterisation, quantitative structural modelling, and geochemical inversion.In marine seismic acquisition the vertical cable concept utilises hydrophones suspended at fixed locations vertically within the water column by buoys. There are numerous advantages of vertical cable technology over conventional 3-D seismic acquisition. In a related methodology, 'Borehole Seismic', seismic energy is passed between wells and valuable information on reservoir geometry, porosity, lithology, and oil saturation is extracted from the P-wave and S-wave data.In association with seismic methods of determining the external geometry and the internal properties of a reservoir, 3-dimensional sedimentation-simulation models, based on physical, hydrologic, erosional and transport processes, are being utilised for stratigraphic analysis. In addition, powerful, 1-D, coupled reaction-transport models are being used to simulate diagenesis processes in reservoir rocks.At the regional scale, the bridging of quantitative structural concepts with seismic interpretation has led to breakthroughs in structural analysis, particularly in complex terrains. Such analyses are becoming more accurate and cost effective when tied to highly advanced, remote-sensing, multi-spectral data acquisition and image processing technology. Emerging technology in petroleum geochemistry, enables geoscientists to infer the character, age, maturity, identity and location of source rocks from crude oil characteristics ('Geochemical Inversion') and to better estimate hydrocarbon-supply volumetrics. This can be invaluable in understanding petroleum systems and in reducing exploration risks and associated expenses.

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

10.5194/egusphere-egu2020-6145 ◽

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

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). 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.Efforts have been under way to construct and test DPG responses in the laboratory. But the sensitivity and long&#8208;period response are difficult to calibrate as they &#160;vary with temperature and pressure, and perhaps by hardware of the same mechanical specifications. &#160;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.&#160;The results compare favorably with calibrations estimated independently through post&#8208;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.&#160;

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

10.5194/egusphere-egu2020-9018 ◽

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

The Caribbean plate has a complex tectonic history, which makes it&#160; 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);&#160; 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.

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

10.1190/sbgf2015-243 ◽

2015 ◽

Cited By ~ 2

Author(s):

Dwight V. Sukup ◽

Patricia F. Crawford

Keyword(s):

Gulf Of Mexico ◽

P Wave ◽

Ocean Bottom

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P-wave velocity structure in the northern part of the central Japan Basin, Japan Sea with ocean bottom seismometers and airguns

Earth Planets and Space ◽

10.1186/bf03352509 ◽

2004 ◽

Vol 56 (5) ◽

pp. 501-510 ◽

Cited By ~ 15

Author(s):

Takeshi Sato ◽

Masanao Shinohara ◽

Boris Y. Karp ◽

Ruslan G. Kulinich ◽

Nobuhiro Isezaki

Keyword(s):

Wave Velocity ◽

Velocity Structure ◽

Japan Sea ◽

P Wave ◽

Ocean Bottom ◽

Japan Basin ◽

Central Japan ◽

P Wave Velocity ◽

Ocean Bottom Seismometers ◽

P Wave Velocity Structure

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Separating quasi-P-wave in transversely isotropic media with a vertical symmetry axis by synthesized pressure applied to ocean-bottom seismic data elastic reverse time migration

Geophysics ◽

10.1190/geo2016-0108.1 ◽

2016 ◽

Vol 81 (6) ◽

pp. C295-C307 ◽

Cited By ~ 3

Author(s):

Pengfei Yu ◽

Jianhua Geng ◽

Chenlong Wang

Keyword(s):

Transversely Isotropic ◽

P Wave ◽

Ocean Bottom ◽

Receiver Side ◽

Reverse Time ◽

Reverse Time Migration ◽

Time Migration ◽

Isotropic Media ◽

Wave Imaging ◽

Obs Data

Quasi-P (qP)-wavefield separation is a crucial step for elastic P-wave imaging in anisotropic media. It is, however, notoriously challenging to quickly and accurately obtain separated qP-wavefields. Based on the concepts of the trace of the stress tensor and the pressure fields defined in isotropic media, we have developed a new method to rapidly separate the qP-wave in a transversely isotropic medium with a vertical symmetry axis (VTI) by synthesized pressure from ocean-bottom seismic (OBS) data as a preprocessing step for elastic reverse time migration (ERTM). Another key aspect of OBS data elastic wave imaging is receiver-side 4C records back extrapolation. Recent studies have revealed that receiver-side tensorial extrapolation in isotropic media with ocean-bottom 4C records can sufficiently suppress nonphysical waves produced during receiver-side reverse time wavefield extrapolation. Similarly, the receiver-side 4C records tensorial extrapolation was extended to ERTM in VTI media in our studies. Combining a separated qP-wave by synthesizing pressure and receiver-side wavefield reverse time tensorial extrapolation with the crosscorrelation imaging condition, we have developed a robust, fast, flexible, and elastic imaging quality improved method in VTI media for OBS data.

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Crustal structure across the Southwest Newfoundland Transform Margin

Canadian Journal of Earth Sciences ◽

10.1139/e88-070 ◽

1988 ◽

Vol 25 (5) ◽

pp. 744-759 ◽

Cited By ~ 40

Author(s):

B. J. Todd ◽

I. Reid ◽

C. E. Keen

Keyword(s):

Continental Crust ◽

Transition Zone ◽

Crustal Structure ◽

P Wave ◽

Ocean Bottom ◽

Ocean Bottom Seismometer ◽

Structure Information ◽

Grand Banks ◽

Air Gun ◽

Transform Margin

A seismic-refraction survey providing deep crustal structure information of the continent–ocean boundary across the South-west Newfoundland Transform Margin was carried out using large air-gun sources and ocean-bottom seismometer receivers. Continental crust ~30 km thick beneath the southern Grand Banks (P-wave velocity = 6.2–6.5 km/s) thins oceanward to a 25 km wide transition zone. In the transition zone, Paleozoic basement of the Grand Banks (5.5–5.7 km/s) is replaced by a basement of oceanic volcanics and synrift sediments (4.5–5.5 km/s). Seaward of the transition zone the crust is oceanic in character, with a velocity gradient from 4.7 to 6.5 km/s and a thickness of 7–8 km. Oceanic layer 3 is absent. No significant thickness of intermediate-velocity (>7 km/s) material is present at the continent–ocean transition, indicating that no under-plating of continental crust has taken place. The continent–ocean transition across the transform margin is much narrower than across rifted margins, supporting the theory that formation of the transform margin is by shearing of continental plates.

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