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Near Sea Bed Characterization Study Using Sholte Wave Data Offshore Abu Dhabi - UAE

Belaid, Kamel H.*1; Moshchenko, Anastasia 2; Strobbia, Claudio L.2; Matarid, Tarek 1
(1) Geosciences, ADMA-OPCO, Abu Dhabi, United Arab Emirates. (2) WesternGeco, Abu Dhabi, United Arab Emirates.

In conventional seismic data processing Scholte and Guided Wave data are normally considerd as noise and therefore, are removed at an early stage of seismic data processing.

This paper describes an innovative approach in characterizing near sea bed sediments using Scholte wave data. The ultimate objective of this study was to attempt to locate the closest area to borrow the necessary volume of sediments/sand for the construction of artificial Islands which are required for the development of an offshore oil field.

The works was carried out in Phases.

Phase-1 consisted of the extraction of the dispersion curves of the Scholte wave fundamental mode along one 2D OBC (Ocean Bottom Cable) seismic test line using both hydrophone and geophone shot records. These dispersion curves were inverted to Vs section which was converted later on to Vp section.

The main observations made at the completion of this Phase1 are:

-Sea bottom does not appear to be characterized by a very slow velocity.

-There is no evidence of marine un-lithified sediments which are in general characterized by very low Vs.

-Local calibration with other data sets (borehole cores, geotechnical & geophysical Surveys) can assist to validate the results of the Scholte wave data Study.

Phase-2 consisted of the processing of an area of 120 km2 of 3D OBC seismic data using the same approach applied in Phase-1. Vs and Vp cubes were produced and are showing very consistent and encouraging results. A relatively low velocity area was identified and will be investigated during Phase-3.

Phase3 consists in the interpretation and analysis of several borehole cores and geotechnical data sets which were acquired in the subject offshore field.

The integration of all available seismic, geological and geotechnical data was carried out and showed an encouraging results.

The results of the three Phase study will be described in the full paper and presented at the next coming Geo2012. conference.

 

AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain