Price, D, Angus, DAC, Chambers, K et al. (1 more author) (2015) Surface microseismic imaging in the presence of high-velocity lithological layers. Geophysics, 80 (6). WC117-WC131. ISSN 0016-8033
Abstract
Surface microseismic monitoring above regions containing high-velocity units will be influenced by a reduction in the effective array aperture and contain significant seismic coda due to an increase in reflected and converted wave energy, which can influence the capability of surface arrays to image microseismic events. We have examined the imaging difficulties due to the reduction of the effective array aperture and increased coda within microseismic data caused by the presence of a fast anhydrite layer. We have generated and used finite-difference, full-waveform microseismic synthetics derived from 1D sonic log data taken from an unconventional shale reservoir in complex anhydrite geology. Two imaging techniques are used to locate the synthetic microseismic events. We use a simplistic and easily reproducible standard diffraction imaging procedure and a more sophisticated technique, Moment Tensor Microseismic Imaging™ (MTMI™). We have confirmed that the presence of high-velocity layers, such as anhydrite, reduce the overall aperture of a surface array, which result in poor resolution of imaged events and reduction in the accuracy of event locations. More importantly, we have determined that the coda in the microseismic data can isolate itself from the direct arrival, stacked into the final imaging result, and it can be misinterpreted as separate events located directly below the true source location, which is unavoidable given the ambiguity between event location and time. Comparison of the two imaging procedures found that even though the more sophisticated MTMI was able to better cope with the effects caused by high-velocity layers, it still demonstrated a significant reduction in resolution of imaged events, a reduction in accuracy, and evidence of multiple and converted energy still present in the final imaging result.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2015 Society of Exploration Geophysicists. All rights reserved. This is an author produced version of a paper published in Geophysics. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | microseismic, subsalt, imaging |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Funding Information: | Funder Grant number EPSRC EP/K021869/1 EPSRC EP/K035878/1 NERC NE/L000423/1 EPSRC EP/K035878/1 Rockfield Software Ltd No External Ref |
Depositing User: | Symplectic Publications |
Date Deposited: | 13 Jul 2015 11:11 |
Last Modified: | 19 Jan 2018 06:29 |
Published Version: | http://dx.doi.org/10.1190/geo2015-0242.1 |
Status: | Published |
Publisher: | Society of Exploration Geophysicists |
Identification Number: | 10.1190/geo2015-0242.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:87924 |