Modeling Borehole Stoneley Wave Propagation Across Permeable In-Situ Fractures
Name
1991.3 Tang et al.pdf
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Author(s)
Tang, X. M.
Cheng, C. H.
Paillet, F. L.
Date Issued
1991
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1991-03
Abstract
The characterization of hydraulic transmissivity of permeable fracture reservoirs is a
very important task in the exploration of water resources and hydrocarbons. Previous
studies that model the permeable structure as a single fluid-filled fracture failed to
explain the observed significant Stoneley wave attenuation across the permeable structure.
In this paper, the structure is modeled as a permeable fracture zone and synthetic
Stoneley wave seismograms in the vicinity of the structure are calculated. The results
show that Stoneley waves can be strongly attenuated or even eliminated without significant
reflection, because of the dissipation of wave energy into the permeable zone.
Several field cases are also modeled and the theoretical results are compared with the
field data. It is shown that low- and medium-frequency Stoneley waves (1 kHz data from
Moodus, Conneticut, and 5 kHz data from Monitoba, Canada) are very sensitive to the
permeability of the fractures and can be used to assess permeability from in-situ logging
data, if the fracture porosity and zone thickness can be measured. At high frequencies,
however, Stoneley waves are not very sensitive to permeability but are mainly affected
by the sum of the fracture openings expressed as the product of fracture zone thickness
and porosity in the fracture zone. This finding is demonstrated by a logging data set
(Monitoba, Canada) obtained using high-frequency Stoneley waves at 34 kHz.
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