Robust summation of dual‐sensor ocean‐bottom cable data

1998 ◽  
Author(s):  
Jianwu Jiao ◽  
Stewart Trickett ◽  
Brian Link
Keyword(s):  
Ocean Bottom ◽  
Dual Sensor

scholarly journals Lithology estimation from a multicomponent 3D-4C OBC seismic survey over a clastic reservoir in the Arabian Gulf

GeoArabia ◽  
2008 ◽  
Vol 13 (1) ◽  
pp. 15-34
Author(s):  
Costas G. Macrides ◽  
Fernando A. Neves
Keyword(s):  
Arabian Gulf ◽  
Seismic Facies ◽  
Seismic Survey ◽  
Ocean Bottom ◽  
Converted Wave ◽  
Flip Flop ◽  
Time Migration ◽  
Dual Sensor ◽  
Seismic Facies Analysis ◽  
Reservoir Quality Index

ABSTRACT In 2002, Saudi Aramco conducted its first 3D, 4-component (4C) ocean-bottom cable (OBC) seismic survey in the Arabian Gulf. The main objective was to delineate the middle Cretaceous Upper Khafji Sand Stringers Reservoir overlying the massive Main Khafji Sand Reservoir in the Zuluf field. The Upper Khafji Sand Stringers Reservoir in the Wasia Formation is typically characterized by weak acoustic impedance contrasts. A pre-survey modeling study, based on the logs of compressional (P) and shear-wave (S) velocities (Vp and Vs), indicated that converted compressional-to-shear waves (P-S) could better-image the structure and stratigraphy of the target reservoir. Commensurate with the objectives of the experiment, a pilot 100-square-kilometer survey was acquired with an inline swath-shooting geometry that employed two seabed receiver cables, with a symmetric split-spread deployment of the 4-C sensors. The acquisition geometry consisted of six sail lines per swath with a single-boat, dual-source, flip-flop configuration. The data were processed through dual-sensor summation, horizontal-component rotation and P-P/P-S pre-stack time migration. Post-stack enhancement using non-stationary Gabor deconvolution proved beneficial in compensating for the missing high frequencies in the acquired converted-wave data. Well-to-seismic calibration for both P-P and P-S data at five wells aided in the interpretation of the data. Five horizons were interpreted and correlated between the P-P and P-S sections. The horizons were analyzed using both amplitude and interval times such that the lateral variations of the Vp/Vs ratio of the Upper Khafji Sand Stringers Reservoir could be mapped. A region of low Vp/Vs ratios in the northwest quadrant, obtained from the isochron interval-time analysis, was correlated with higher ‘net sand’ pay at a hidden well located in the middle of this region. These results were further corroborated by seismic facies analysis and provide a qualitative reservoir quality index in the Upper Khafji Sand Stringers Reservoir.

Combining Dual-Sensor Ocean Bottom Cable Traces - a Comparison of Methods

1997 ◽  
Author(s):  
F.J. Barr ◽  
R.E. Chambers ◽  
W. Dragoset ◽  
J. Paffenholz
Keyword(s):  
Ocean Bottom ◽  
Comparison Of Methods ◽  
Dual Sensor

Rayleigh-Marchenko redatuming for target-oriented, true-amplitude imaging

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. S439-S452 ◽  
Author(s):  
Matteo Ravasi
Keyword(s):  
Seismic Data ◽  
Field Data ◽  
Scaling Factor ◽  
Velocity Analysis ◽  
Ocean Bottom ◽  
Structural Imaging ◽  
Dual Sensor ◽  
Band Limited ◽  
Borehole Seismic ◽  
Amplitude Versus

Marchenko redatuming is a revolutionary technique to estimate Green’s functions from virtual sources in the subsurface using only data measured at the earth’s surface, without having to place either sources or receivers in the subsurface. This goal is achieved by crafting special wavefields (so-called focusing functions) that can focus energy at a chosen point in the subsurface. Despite its great potential, strict requirements on the reflection response such as knowledge and accurate deconvolution of the source wavelet (including absolute scaling factor) and co-location of sources and receivers have so far challenged the application of Marchenko redatuming to real-world scenarios. I combine the coupled Marchenko equations with a one-way version of the Rayleigh integral representation to obtain a new redatuming scheme that handles internal as well as free-surface multiples using dual-sensor, band-limited seismic data (with an unknown source signature) from any acquisition system that presents arbitrarily located sources above a line of regularly sampled receivers—for example, ocean-bottom, source-over-spread streamer, and horizontal borehole seismic data. The redatuming scheme is validated using synthetic and field data, and the retrieved subsurface wavefields are used for improved structural imaging and taken as input for the computation of true-amplitude angle gathers, which can lead to more accurate amplitude-versus-angle interpretation and velocity analysis.

A new seismic methodology to significantly improve deeper data character and interpretability on the North West Shelf

2009 ◽  
Vol 49 (2) ◽  
pp. 572
Author(s):  
Andrew Long ◽  
Guillaume Cambois ◽  
Gregg Parkes ◽  
Anders Mattsson ◽  
Terje Lundsten
Keyword(s):  
Beam Steering ◽  
Ocean Bottom ◽  
Flip Flop ◽  
Surface Reflection ◽  
North West ◽  
The North ◽  
Dual Sensor ◽  
Shot Point ◽  
Different Depths ◽  
Marine Seismic

The sea-surface reflection generates interferences between up- and down-going waves that ultimately limit the bandwidth of marine seismic data. This phenomenon known as ghosting actually occurs twice—on the source side and on the receiver side. Ghost attenuation or elimination to increase the signal bandwidth has been the focus of extensive research. The receiver ghost can be removed using dual-sensor ocean-bottom devices (Barr and Sanders, 1989), a dual-sensor towed streamer (Carlson et al, 2007) or an over/under streamer acquisition (Brink and Svendsen, 1987). The over/under technique can also be used to remove the source ghost (Moldoveanu, 2000) but it requires flip-flop shooting of two sources at two different depths, ultimately halving the survey shot-point density. Alternatively, the source ghost can be attenuated using a beam steering technique originally developed some 60 years ago for dynamite land acquisition (Shock, 1950). The principle is to detonate charges at various depths in a sequence that constructively builds the down-going wave at the expense of the up-going wave. This way the energy of the ghost (the surface-reflected up-going wave) is reduced compared to that of the primary pulse. In this paper we adapt the beam steering approach to airgun arrays in the marine environment.

A comparison of methods for combining dual‐sensor ocean‐bottom cable traces

1997 ◽  
Author(s):  
F. J. Barr ◽  
R. E. Chambers ◽  
W. Dragoset ◽  
J. Paffenholz
Keyword(s):  
Ocean Bottom ◽  
Comparison Of Methods ◽  
Dual Sensor
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