Estimation of fracture compliance from tubewaves generated at a fracture intersecting a borehole
Name
Bakku_fracture_compliance.pdf
Size
284.37 KB
Format
Adobe PDF
Checksum (MD5)
4655239b0c645f9e09017dcf6e9f4c34
Author(s)
Bakku, Sudhish Kumar
Fehler, Michael
Burns, Daniel R.
Date Issued
2011
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;2011-11
Abstract
Understanding fracture compliance is important for characterizing fracture networks and for inferring fluid flow in the subsurface. In an attempt to estimate fracture compliance in the field, we developed a new model to understand tubewave generation at a fracture intersecting a borehole. Solving the dispersion relation in the fracture, amplitude ratios of generated tubewave to incident P-wave were studied over all frequency ranges. Based on the observations from the model, we propose that measuring amplitude ratios near a transition frequency can help constrain fracture compliance and aperture. The transition frequency corresponds to the regime where the viscous skin depth in the fracture is comparable to its aperture. However, measurements in the high frequency limit can place a lower bound on fracture compliance. Comparing the model to a previously published VSP dataset, we argue that compliance values of the order 10[superscript −10] −10[superscript −9] m/Pa may be possible in the field.
Subjects
Fractures
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