ABSTRACT:

Multi-component 2D/3D seismic is gaining more and more attention in the E&P world. This seismic methodology is already established as a suitable tool for imaging through gas clouds, for fluid detection and for petrographic characterization. The importance of multi-component surveys relies on the possibility of recording Shear or Converted waves by means of inline and crossline horizontal geophones. Regarding offshore surveys the multi-component methodology is based on Ocean Bottom Cables, a technology that allows the recording of compressional and shear waves directly at the Sea floor. In the recent years Agip performed two OBC acquisitions: a 2D survey in the North Sea, aimed to improve the imaging through gas chimney, and a 3D multi-azimuth, multi-offset survey in the Adriatic Sea aimed to characterize the fracture setting in a carbonatic reservoir. The extra cost of a shear waves acquisition and processing compared to the cost of a standard P wave acquisition is an issue to be carefully considered in evaluating the feasibility of a multi-component project. In some cases the cost can even quadruplicate. There is no doubt that the extra costs would be lowered if shear waves operations were more widely used. The usefulness of multi-component seismic will be discussed through the presentation of the main features of the two Agip surveys and other case histories.

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