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Deep and Shallow Surface Seismic Integration with TDEM, Gravity, VSP, and Logs in South Oman.Normal access

Authors: A.S. Al-Ismaili, J. Shorter, M. Hadhrami, A. Harthy, A. Obeidi and M. Azam
Event name: Fourth EAGE Exploration Workshop
Session: Integration of Non-Seismic Geophysical Data with Seismic
Publication date: 02 May 2017
DOI: 10.3997/2214-4609.201700217
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 1.35Mb )
Price: € 20

Near surface geology in south of Oman is believed to cause static instability, hence affecting seismic imaging. Such phenomena like low-velocity anomalies are suspected to generate pull-down artefacts as these features often correspond to intra-field lows. This effect is extends to deeper horizons and gets wider with depth. Refraction static is usually used by seismic industry to construct near surface velocity. This has been proven successful in some areas. However, because it is data dependent and the method assumes an increase in velocity with depth, it will not work to identify low-velocity anomalies, suspected in this area. Therefore, alternative methods need to be investigated. VSP, logs, Time Domain electromagnetic (TDEM), gravity lines, and 2D seismic were acquired. Each method is expected to give its own overview of the problem, but integrating all data will provide better understanding on extent and magnitude of the phenomena. Resistivity logs converted to velocity for the upholes shows good agreement with sonic, which proved the robustness of Faust’s equation at study area, as results this equation enabled the construction of velocity model for near surface from TDEM data. All data invalidate the existence of shallow anomaly. Therefore, the intra-field lows are considered to be real.

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