| Summary: | Field testing has been conducted to evaluate a model which predicts the
permeability and orientation of a permeable zone, in a deep water well in crystalline
rock. Tube waves are generated by seismic P-waves incident on a fracture
intersecting the borehole, a process observed in vertical seismic profiling (VSP). The
behavior is explained by fluid exchange between the fracture and borehole, and the
observed efficiency of conversion is theoretically related to fracture permeability.
Additionally, fracture orientation may be obtained from multiple-source-offset VSP
surveys. Conventional temperature, caliper, resistivity and televiewer logs show the
presence of fractures and their orientation, and provide indirect evidence of
associated flow. Open fractures are simultaneously sampled over the full borehole
depth by hydrophone VSP methods. The tube wave generation model produces results
which compare favorably to independent estimates of fracture parameters.
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