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Title: Shear wave transducer for stress measurements in boreholes

A technique and apparatus for estimating in situ stresses by measuring stress-induced velocity anisotropy around a borehole. Two sets each of radially and tangentially polarized transducers are placed inside the hole with displacement directions either parallel or perpendicular to the principal stress directions. With this configuration, relative travel times are measured by both a pulsed phase-locked loop technique and a cross correlation of digitized waveforms. The biaxial velocity data is used to back-calculate the applied stress.
Authors:
 [1]
  1. (Castro Valley, CA)
Publication Date:
OSTI Identifier:
866134
Report Number(s):
US 4641520
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Patent
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
Country of Publication:
United States
Language:
English
Subject:
shear; wave; transducer; stress; measurements; boreholes; technique; apparatus; estimating; situ; stresses; measuring; stress-induced; velocity; anisotropy; borehole; sets; radially; tangentially; polarized; transducers; placed; inside; displacement; directions; parallel; perpendicular; principal; stress; directions; configuration; relative; travel; times; measured; pulsed; phase-locked; loop; technique; correlation; digitized; waveforms; biaxial; velocity; data; back-calculate; applied; stress; shear wave; placed inside; travel time; stress measurements; phase-locked loop; measuring stress; wave transducer; velocity anisotropy /73/367/