Name
1994.5 Tezuka et al.pdf
Size
825.85 KB
Format
Adobe PDF
Checksum (MD5)
d1bedce097449596806f7f82a810f7b6
Author(s)
Tezuka, Kazuhiko
Cheng, C. H.
Tang, X. M.
Date Issued
1994
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1994-05
Abstract
This paper describes a propagator matrix formulation for the problem of the Stoneley
wave propagation in an irregular borehole. This is based on a simple one-dimensional
theory that is possible for the low frequency Stoneley wave, because it is a guided
wave with no geometrical spreading in the borehole. The borehole and the surrounding
formation are modeled by multi-layers discretized along the borehole axis, then the
propagator matrices at each boundary are calculated. The mass balance boundary
condition is introduced to express an interaction of the Stoneley wave at the interfaces
which include radius changes.
We have used the method to investigate the reflection and the transmission characteristics of the Stoneley wave with several models. The results are consistent with
the results obtained by other existing modeling methods such as the finite difference
method and the boundary integral method. The calculation speed is much faster than
those of the other methods.
We have applied the method to the field data to simulate the synthetic iso-offset
records and have compared them with the actual field records. The results show a good
agreement in the major reflections due to the washout zones and an important disagreement
in the reflections related to the fractures. This result suggests the possibility of
distinguishing the fracture induced reflections from others.
Through this study, we found that the proposed method is efficient in modeling
the low frequency Stoneley wave propagation in the irregular borehole, especially in
simulating the synthetic iso-offset records, which provide helpful information in the
evaluation of fractures.
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