Seismic imaging of the Kylylahti Cu-Au-Zn ore deposit using conventional and DAS VSP measurements supported by 3D full-waveform seismic modeling

Marko Riedel, Calin Cosma, Kari Komminaho, Nicoleta Enescu, Emilia Koivisto, Michal Malinowski, Tuija Luhta, Sanna Juurela, COGITO-MIN Working Group

Tutkimustuotos: Artikkeli kirjassa/raportissa/konferenssijulkaisussaKonferenssiartikkeliAmmatillinen

Abstrakti

The focus of this study is reflection seismic imaging of a massive sulfide ore deposit in the Kylylahti Cu-Au-Zn mine in eastern Finland. The geological environment in the target area is dominated by high-velocity rocks which have been severely folded resulting in a complicated assemblage of various near-vertical structures. In order to image those, we rely on VSP data that were acquired in the Kylylahti mine using conventional three-component geophones in four boreholes as well as a fiber-optic Distributed Acoustic Sensing (DAS) cable in one borehole. The boreholes were located within a few hundreds of meters from the known ore body. The use of high-frequency VSP systems directly within the mine is a fortunate situation which enables very good spatial resolution. Despite this, the processing and interpretation of the acquired data is not straightforward due to the geological complexity of the area. Elastic three-dimensional full-waveform seismic modeling was conducted in order to facilitate the understanding of the acquired data. For this purpose, a realistic geological model of the environment was constructed based on extensive borehole data and petrophysical laboratory measurements. Using this model in combination with the true acquisition geometry, a synthetic dataset was generated which is a very close representation of the acquired field data. Based on the synthetics, target reflection signatures were traced to their geological origins and then linked to similar features in the acquired field data. Both datasets were processed in the same way and then migrated in order to map the recorded reflections in 3D space. The resulting reflectivity sections show the ore signature, as well as other dominant lithological contrasts, with high spatial accuracy. We conclude that the applied conventional and DAS VSP methodologies provide sufficient spatial accuracy to correctly image the sub-vertical ore deposit. However, in order to confidently interpret the acquired data in such a challenging environment, realistic synthetic modeling is required to understand the recorded signals with respect to their geological origins.
Alkuperäiskielienglanti
OtsikkoProceedings of Exploration ’17 : Seismic Methods & Exploration Workshop
ToimittajatG. Bellefleur, B. Milkereit
Sivumäärä7
KustantajaDecennial Mineral Exploration Conferences
Julkaisupäivälokak. 2017
Sivut57-63
Artikkeli noPaper 10
TilaJulkaistu - lokak. 2017
OKM-julkaisutyyppiD3 Artikkeli ammatillisessa konferenssijulkaisussa
TapahtumaExploration - Toronto, Kanada
Kesto: 21 lokak. 201725 lokak. 2017

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