Method and apparatus for indirect determination of shear velocity from guided modes

Patent · Tue Dec 30 04:00:00 EST 1986

OSTI ID:6841729

Ingram, J D; Liu, O Y

A method is described of estimating shear wave slowness of formations traversed by a borehole from acoustic log data including guided wave comprising the steps of: generating acoustic energy at a point in the borehole, receiving that acoustic energy as acoustic signals in the form of full waveforms, which include as a portion thereof waveforms representing guided waves, at each of at least four receiver stations spaced one from the other and from the point at which the acoustic energy was generated, windowing each of the full waveforms to identify those portions representing a guided wave, determining the phase velocity and frequency of the guided wave from that portion of the full waveform representing the guided wave, measuring the values for formation density, drilling fluid density, drilling fluid slowness, borehole diameter, and Poisson's ratio, establishing a multi-dimensional matrix comprised of given ranges of assumed values of guided wave frequency, Poisson's ratio, drilling fluid slowness, drilling fluid density, formation density, guided wave phase velocity and borehole diameter, fitting the measured values to the multi-dimensional matrix to obtain an estimate of shear wave slowness at the point in the borehole, and recording the estimate as a function of depth.

• Assignee: NOV; EDB-87-036990; NOV-87-042370
• Patent Number(s): US 4633449
• OSTI ID: 6841729
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580203 -- Geophysics-- Geophysical Survey Methods-- (1980-1989)
ACOUSTIC MEASUREMENTS
BOREHOLES
CAVITIES
DATA PROCESSING
DENSITY
DEPTH
DIMENSIONS
DRILLING FLUIDS
FLUIDS
FREQUENCY MEASUREMENT
GEOLOGIC DEPOSITS
MATRICES
MECHANICAL PROPERTIES
MINERAL RESOURCES
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
PHASE VELOCITY
PHYSICAL PROPERTIES
POISSON RATIO
PROCESSING
RESOURCES
SEISMIC WAVES
SHEAR
SONIC LOGGING
VELOCITY
WAVE FORMS
WELL LOGGING