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FWI for Sub-surface Imaging in the Context of Seismic while Drilling - Synthetic Study
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 74th EAGE Conference and Exhibition incorporating EUROPEC 2012, Jun 2012, cp-293-00483
- ISBN: 978-90-73834-27-9
Abstract
Seismic data acquired while drilling can be used to complement the information provided by surface seismic and reduce drilling hazards. In this paper, we investigate the potential of full waveform inversion (FWI) to provide an update of the subsurface image ahead of and around the drill bit while drilling. Inversion tests are carried out for three different acquisition configurations: surface to wellbore seismic, well to well seismic and wellbore seismic with sources and receivers placed along the drill string. A 2D visco acoustic FWI code in the frequency-space domain is used. We considered a deep section of a simplified P-wave velocity model based on data from the Norne field. A fault, considered as a target in the numerical experiment, is created by shifting the layers along an oblique line. The method is applied to a smooth initial P-wave velocity model. For the different acquisition geometries, the final velocity models show that the method can provide clear indications about the presence of the fault ahead of the drill bit. The quality of the models depends on the acquisition geometry. The spurious artefacts observed in the low illuminated zones reflect the strong signature of the acquisition geometry in the inversion results.