Estimating the fracture density of small-scale vertical fractures when large-scale vertical fractures are present
Name
Liu_etal_Estimating the fracture density of small-scale vertical fractures when large-scale vertical fractures are present.pdf
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162.76 KB
Format
Adobe PDF
Checksum (MD5)
f79713076232d1d86deca77549e1794e
Author(s)
Liu, Yuwei
Fehler, Michael
Fang, Xinding
Liu, Cai
Date Issued
2013
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;2013-07
Abstract
When fractures are vertical, aligned and their dimensions are small relative to the seismic wavelength, the medium can be considered to be an equivalent Horizontal Transverse Isotropic (HTI) medium. However, geophysical data acquired over naturally fractured reservoirs often reveal the presence of multiple fracture sets. We investigate a case where there are two vertical sets of fractures having differing length scales. One fracture set has length scale that is much smaller than the seismic wavelength but the other has length scale that is similar to the seismic wavelength. We use synthetic data to investigate the ability to infer the properties of the small-scale fractures in the presence of the large-scale fracture set. We invert for the Thomsen-type anisotropic coefficients of the small-scale fracture set by using the difference of the P-wave amplitudes at two azimuths, which makes the inversion convex. Then we investigate the influence of the presence of the large-scale fractures on our ability to infer the properties of the small-scale fracture set. Surprisingly, we find that we can reliably infer the fracture density of the small scale fractures even in the presence of large scale fractures having significant compliance values.
Subjects
Fractures
Inversion
Persistent DSpace Link
