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Impact of Near-surface Velocities on Surface Microseismic Signal, a Case Study in the Fayetteville FormationNormal access

Authors: A. Gendrin, E. Muyzert, M. Williams, I. Bradford, I. Rodriguez and A. Probert
Event name: 77th EAGE Conference and Exhibition 2015
Session: Microseismic Event Detection and Localization
Publication date: 01 June 2015
DOI: 10.3997/2214-4609.201413015
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 3.82Mb )
Price: € 20

A near-surface velocity map is derived, using data from active shots, acquired in the frame of a surface microseismic survey, targeting the Fayetteville shale formation. This near-surface velocity map shows strong velocity variations with velocities ranging from a few hundreds of metres per second to approximately 1500 m/s. The visibility of the S-wave expression on the vertical component of surface geophones was investigated. It was found that only one-third of the events showed a visible S-wave arrival, and this arrival was below the level of noise for the other two-thirds of the events. When the S-wave is observed, it is seen preferentially in areas where near-surface velocities are larger and attenuation is lower. The use of only P-waves appears to be widespread in surface microseismic processing. This study suggests, through the derivation of a near-surface velocity map, that near-surface attenuation could be one factor justifying this approach.

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