Modern Seismic Imaging of a Vintage 3-D Seismic Survey Offshore Northern Emirates

Michael A. Hall¹*, Svetlana Bidikhova¹, and John Faragher^2
1GX, Canada
²GX, USA
*[email protected]

This presentation covers the issues involved in the pre-stack imaging of a vintage offshore 3-D dataset and preparing it for modern processing technologies. The spatial sampling of 3-D seismic surveys was considerably more coarse two decades ago than it is today. Within the survey is a substantial gap in short offsets due to the under-shooting of platforms. This paucity of acquired data creates problems for pre-stack migration, especially around the under-shoot areas. The data acquisition used an analogue streamer resulting in strong variations in sensitivity between hydrophone groups. The data suffered from several issues relating not only to acquisition but to transcription and this presentation will address how these were satisfactorily dealt with. Common to this part of the Arabian Gulf is a guided wave noise train that obscures reflections on the longer offsets. An effective attenuation of this unwanted noise is presented that preserves the desired signal and allows the inclusion of longer offset data into the stack. This region is also renowned for severe multiple reflection problems both from the water layer and from strongly reflecting interfaces in the Earth itself. A new approach will be shown to attenuating both surface related and inter-bed multiple reflection energy. Well data and geological information were carefully integrated in the construction of the velocity model to yield improved imaging of the primary reflection data. Comparisons will be made for pre-stack time migration using the sparsely recorded data only against interpolating and regularizing this data prior to migration.

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