A New Approach to Water Velocity Estimation and Correction

Carvill, Charles

doi:10.3997/2214-4609.201400384

Cited by 8 publications

(2 citation statements)

References 3 publications

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“…The acquisition of the legacy surveys spanned more than 10 years, and one of the underlying surveys took more than one year to acquire. Considering the ultra-deep water, water velocity correction (WVC), (Carvill, 2009) is critical to align all the data to the same reference water velocity. The reference water velocity is derived according to the TS Dip measurement from the Base survey.…”

Section: Methodsmentioning

confidence: 99%

Optimum signal re-processing of multiple legacy surveys to improve pre-salt imaging in the complex Santos Basin, Brazil

2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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SantosBasin is emerging as one of the world's most promising exploration and production areas. The pre-salt region is complex, with fast carbonates, slow sediments, volcanic layers, and large fault systems. Together with the complicated overburden structures including carbonate layers in the post salt and stratified salt, high-resolution imaging is critical to better understand the producing fields and to facilitate development of others. High-resolution imaging relies on adequate illumination, seismic data with sufficient resolution and a good signal-to-noise (SNR), and an accurate velocity model. The accuracy of the velocity model is also dependent on the quality of seismic data. In the central Santos Basin, by combining several legacy surveys along different shooting directions, we show that the illumination of the target zones is increased. With signal processing technologies developed in recent years, we show that the SNR and resolution of the data were improved. Surface multiple attenuation is challenging in this area due to the existence of high-velocity, steepdipping post-salt carbonates and stratified evaporites. We show that multiple prediction is improved by the larger crossline aperture enabled by the incorporation of all the legacy data; therefore, improved multiple elimination was achieved. With the reprocessed higher resolution and higher SNR data and increased azimuth sampling, a more accurate velocity model is inverted by contemporary model building technologies. Finally, delivering high-resolution presalt imaging.

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Section: Methodsmentioning

confidence: 99%

Optimum signal re-processing of multiple legacy surveys to improve pre-salt imaging in the complex Santos Basin, Brazil

2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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“…To ensure that all four datasets combine seamlessly, the four legacy datasets were re-datumed to mean sea level during adaptive deghosting (Rickett, 2014;Zarkhidze, et al, 2016) and was followed by water velocity correction (Carvill, 2009) and survey matching. Following this, the combined legacy data were used together for surface multiple prediction (Dragoset et al, 2010) to increase crossline aperture, and therefore improving the surfacemultiple modeling and elimination.…”

Section: Data Preparation For Imagingmentioning

confidence: 99%

Post-migration image optimization of multi-azimuth legacy data in Central Santos Basin

2021

Proceeding of the 17th International Congress of the Brazilian Geophysical

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In complex presalt reservoirs such as the Santos Basin in Brazil, improvements in our techniques for combining and imaging legacy datasets can postpone the need for additional costly seismic acquisitions. In this case study, we show how data from several legacy acquisitions with varying azimuths were carefully combined to create a contiguous multi-azimuth image. Two different migration algorithms are used with each having tailored approaches for the weighting and summation of the migrated data. Compared to the legacy image, significant improvement is attained in terms of signal-to-noise ratio, the coherency of evaporite layers, base salt, presalt, and basement events, and the delineation of the pre-salt faults.

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