--> Abstract: Modeling the Near-Surface Using High-Resolution Seismic Data, by Ramzy M. AlZayer and Tariq Alkhalifa; #90077 (2008)

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Modeling the Near-Surface Using High-Resolution Seismic Data

Ramzy M. AlZayer1* and Tariq Alkhalifa2
1Saudi Aramco
2KACST, Saudi Arabia
*[email protected]

Complex near-surface geology, usually of Quaternary or Tertiary age, is a major problem in land seismic data. It degrades the stacking coherency, and therefore affects velocity analysis as well as the quality of the time-image. Furthermore, long-wavelength anomalies introduce erroneous time structures, a serious interpretation pitfall. Yet more serious, the near-surface might introduce dynamic errors, which influence the isochron technique of mapping and interpretation. The solution to this problem is to remap the data to a datum below the prob-lematic zone. Whether you intend to use simple static corrections or one of the more nu-merically demanding techniques of wavefield extrapolation (i.e. datuming), the first step is to build a near-surface velocity model. Traditional method, such as uphole-based or refrac-tion-based techniques proved to be effective in limited cases. In this presentation, we pro-pose the use of high-resolution seismic data to model the near-surface. The shallow seismic method is a major tool of investigation in engineering and environmental applications. The purpose of this work is to exploit this method to build an equivalent near-surface macro-velocity model. The methodology involves three steps: (1) data acquisition and processing; (2) obtaining the velocity information; and (3) relating this information to borehole data. The result of applying this methodology to synthetic data was an accurate reconstruction of the near-surface model. We have also applied this method to real field data from the Ara-bian Peninsula. The model we obtained resolved deep anomalies (about 350 m deep), which are not usually penetrated by shallow upholes. When comparing our stacked section with a refraction-based one, we noticed marginal improvements in quality, but noticeable differ-ences in time structures. Uphole and geological information in that area support our model.

 

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain