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Hydraulic Properties of Closely Spaced Dipping Open Fractures Intersecting a Fluid‐Filled Borehole Derived From Tube Wave Generation and Scattering
Author(s) -
Minato Shohei,
Ghose Ranajit,
Tsuji Takeshi,
Ikeda Michiharu,
Onishi Kozo
Publication year - 2017
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2017jb014681
Subject(s) - borehole , geology , fracture (geology) , geothermal gradient , fluid dynamics , tube (container) , seismology , scattering , geophysical imaging , hydraulic fracturing , geotechnical engineering , geophysics , mechanics , optics , materials science , physics , composite material
Fluid‐filled fractures and fissures often determine the pathways and volume of fluid movement. They are critically important in crustal seismology and in the exploration of geothermal and hydrocarbon reservoirs. We introduce a model for tube wave scattering and generation at dipping, parallel‐wall fractures intersecting a fluid‐filled borehole. A new equation reveals the interaction of tube wavefield with multiple, closely spaced fractures, showing that the fracture dip significantly affects the tube waves. Numerical modeling demonstrates the possibility of imaging these fractures using a focusing analysis. The focused traces correspond well with the known fracture density, aperture, and dip angles. Testing the method on a VSP data set obtained at a fault‐damaged zone in the Median Tectonic Line, Japan, presents evidences of tube waves being generated and scattered at open fractures and thin cataclasite layers. This finding leads to a new possibility for imaging, characterizing, and monitoring in situ hydraulic properties of dipping fractures using the tube wavefield.