TY - JOUR
T1 - Coda Wave Interferometry for Accurate Simultaneous Monitoring of Velocity and Acoustic Source Locations in Experimental Rock Physics
AU - Singh, Jonathan
AU - Curtis, A.
AU - Zhao, Youqian
AU - Cartwright-Taylor, A.
AU - Main, I.
N1 - Funding Information:
The authors would like to thank Petrobras and Shell for their sponsorship of the International Centre for Carbonate Reservoirs (ICCR), and for permission to publish this work from the 4DRP project. We are also grateful to Ian Butler, Florian Fussies, Phil Cilli, Angus Lomas, and Roseanne Clement for their helpful scientific input and comments. We also acknowledge the thoughtful and constructive reviews of Editor Douglas Schmitt and two anonymous reviewers. The MATLAB code package is available at https://github.com/JonathanSingh/cwi_codes/. The code package of Zhao and Curtis () is available at https://www.geos.ed.ac.uk/eip/codes.html.
Publisher Copyright:
© 2019. The Authors.
PY - 2019/6
Y1 - 2019/6
N2 - In many geoscientific, material science, and engineering applications it is of importance to estimate a representative bulk seismic velocity of materials or to locate the source of recorded seismic or acoustic waves. Such estimates are necessary in order to interpret industrial seismic and earthquake seismological data, for example, in nondestructive evaluation and monitoring of structural materials, and as an input to rock physics models that predict other parameters of interest. Bulk velocity is commonly estimated in laboratories from the time of flight of the first-arriving wave between a source and a receiver, assuming a linear raypath. In heterogeneous media, that method provides biased estimates of the bulk velocity, and of derived parameters such as temporal velocity changes or the locations of acoustic emissions. We show that coda wave interferometry (CWI) characterizes changes in the bulk properties of scattering media far more effectively on the scale of laboratory rock samples. Compared to conventional methods, CWI provides significant improvements in both accuracy and precision of estimates of velocity changes, and distances between pairs of acoustic sources, remaining accurate in the presence of background noise, and when source location and velocity perturbations occur simultaneously. CWI also allows 3-D relative locations of clusters of acoustic emissions to be estimated using only a single sensor. We present a method to use CWI to infer changes in both P and S wave velocities individually. These innovations represent significant improvements in our ability to characterize the evolution of properties of media for a variety of applications.
AB - In many geoscientific, material science, and engineering applications it is of importance to estimate a representative bulk seismic velocity of materials or to locate the source of recorded seismic or acoustic waves. Such estimates are necessary in order to interpret industrial seismic and earthquake seismological data, for example, in nondestructive evaluation and monitoring of structural materials, and as an input to rock physics models that predict other parameters of interest. Bulk velocity is commonly estimated in laboratories from the time of flight of the first-arriving wave between a source and a receiver, assuming a linear raypath. In heterogeneous media, that method provides biased estimates of the bulk velocity, and of derived parameters such as temporal velocity changes or the locations of acoustic emissions. We show that coda wave interferometry (CWI) characterizes changes in the bulk properties of scattering media far more effectively on the scale of laboratory rock samples. Compared to conventional methods, CWI provides significant improvements in both accuracy and precision of estimates of velocity changes, and distances between pairs of acoustic sources, remaining accurate in the presence of background noise, and when source location and velocity perturbations occur simultaneously. CWI also allows 3-D relative locations of clusters of acoustic emissions to be estimated using only a single sensor. We present a method to use CWI to infer changes in both P and S wave velocities individually. These innovations represent significant improvements in our ability to characterize the evolution of properties of media for a variety of applications.
UR - http://www.scopus.com/inward/record.url?scp=85068180399&partnerID=8YFLogxK
U2 - 10.1029/2019JB017577
DO - 10.1029/2019JB017577
M3 - Article
AN - SCOPUS:85068180399
SN - 2169-9313
VL - 124
SP - 5629
EP - 5655
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 6
ER -