Assessing the source radiation pattern (SRP) of onshore seismic data: Preliminary results

Le résumé fourni par la source

The source radiation pattern (SRP) in seismology defines the directional dependence of the magnitude of the seismic energy radiated from a seismic source. An SRP depends on the properties of both the exciting shot and the source volume (SV) upon which the wave motions are excited. Hence, the SRP is often viewed on a lower hemispheric projection of normalized wavefield amplitude on the SV surface. In onshore seismic surveys, variation in medium properties of shot sites and the inhomogeneity of each SV may significantly deviate the SRP from being omnidirectional, an ideal pattern of equal amplitude in all directions. However, the SRP’s have not been well studied in onshore seismic surveys due to many challenges. The objective of this study is to assess the feasibility of estimating the SRP of onshore seismic data using first arrivals and reflections. Since the SRP masks all seismic wavefields emitted from the source, we assume an effective SRP is made of the most consistent long-wavelength patterns among all wavefields on the SV surface, after removing the out-of-source factors such as geometrical spreading and effects from deep structures and receivers. To validate this assumption, we have analyzed reflection and first arrival data of selected common shot gathers from a 3D field survey. The preliminary results indicate there are significant amplitude variations of first arrivals and reflections over the directional angle from each shot. There are consistencies between the long-wavelength patterns of shallow reflections on the SV surface, likely being the effective SRP that warrants further investigations. Presentation Date: Wednesday, September 18, 2019 Session Start Time: 9:20 AM Presentation Start Time: 11:00 AM Location: Poster Station 6 Presentation Type: Poster

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.