Mechanical Compliance of Individual Fractures in a Heterogeneous Rock Mass From Production‐Type Full‐Waveform Sonic Data

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Version: Final published version
License: CC BY-NC-ND 4.0
Serval ID
serval:BIB_F7BF90BC4EA8
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Mechanical Compliance of Individual Fractures in a Heterogeneous Rock Mass From Production‐Type Full‐Waveform Sonic Data
Journal
Journal of Geophysical Research: Solid Earth
Author(s)
Zhou Zhenya, Caspari Eva, Barbosa Nicolás D., Greenwood Andrew, Holliger Klaus
ISSN
2169-9313
2169-9356
Publication state
Published
Issued date
08/2022
Peer-reviewed
Oui
Volume
127
Number
8
Language
english
Abstract
The mechanical fracture compliance is of interest in a number of geoscientific applications. Seismic borehole methods, especially full-waveform sonic (FWS) data, have indicated their potential to infer the compliance of macroscopic fractures under in situ conditions. These approaches rely on the assumption of a homogeneous background embedding the fractures and, as of yet, compliance estimates for individual fractures are limited to static FWS measurements. In this work, we assess the potential of inferring the compliance of individual fractures from standard, production-type FWS data in the presence of background heterogeneity. We first perform a comparative test on synthetic data to evaluate three approaches known as the transmission, phase, and group time delay methods. The results indicate that the former two produce adequate compliance estimates for scenarios with a strongly heterogeneous background or a damage zone around the fracture. These two methods are then applied to two FWS data sets acquired before and after a hydraulic stimulation campaign in a crystalline rock, which allows to test them on natural and man-made fractures. The transmission method turned out to be unsuitable for the considered data due to its reliance on amplitudes. Conversely, the travel time behavior remained stable and the phase time delay method produced robust and consistent estimates. The results for a newly created hydro-fracture imply the capability of resolving remarkably small compliance values of the order of 10−14 m/Pa. This estimate is one order-of-magnitude smaller than that for the natural fracture, which may help to distinguish between these two fracture types.
Keywords
Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Geochemistry and Petrology, Geophysics
Web of science
Open Access
Yes
Create date
05/09/2022 8:50
Last modification date
10/09/2022 6:15
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