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1. (WO2000058757) ACOUSTIC LOGGING APPARATUS AND METHOD

Pub. No.:    WO/2000/058757    International Application No.:    PCT/US2000/007605
Publication Date: Oct 5, 2000 International Filing Date: Mar 22, 2000
IPC: G01V 1/50
Applicants: HALLIBURTON ENERGY SERVICES, INC.
Inventors: MANDAL, Batakrishna
Title: ACOUSTIC LOGGING APPARATUS AND METHOD
Abstract:
An apparatus (figure 2) and method (figure 5) for determining fast and slow shear wave velocities and orientations in an anisotropic earth formation that reduces the error and ambiguity in calculating these parameters and eliminates the need for dipole receivers (104, 106) and multiple dipole sources (102). The apparatus generally includes a single dipole source (200) for generating an acoustic signal within a borehole. The acoustic logging tool contains multiple levels of receivers. At each level, four receivers, (204, 206, 208, 210) which may be conventional pressure transducers, receive shear/flexural wave signals which propagate along the borehole earth formation. These receivers measure the pressure fields from the wave signals. A processing device (214), preferably a UNIXtm based computer, interpolates the measured pressure fields between any two adjacent receivers. The processing device performs cross-component decomposition on the pressure field to determine shear wave orientation and velocity. Using the shear wave orientation and velocity the processing device determines transit time anisotropy, energy anisotropy, and slowness anisotropy.