Abstract: Techniques for displaying sonic logging data that provide highly reliable, visual quality-control (QC) indicators. One aspect herein is directed to a display of sonic logging data corresponding to a slowness frequency analysis (SFA) projection log.

Abstract: Techniques for displaying sonic logging data that provide highly reliable, visual quality-control (QC) indicators. One aspect herein is directed to a display of sonic logging data corresponding to a slowness frequency analysis (SFA) projection log.

Abstract: Systems and methods for determining a formation property related to formation strength and stresses are disclosed. A method for determining a formation strength includes obtaining radial formation property measurements at different wellbore pressures; generating a radial stress profile based on a formation model; generating a radial stress function from the radial stress profile; and comparing the radial formation property measurements with the radial stress function to determine the formation strength. A method for determining a formation stress profile includes deriving formation parameters from a formation radial profiling; obtaining formation log data that comprise formation density data; estimating formation stresses from the formation log data; and deriving a radial stress profile based on a formation model, the derived formation parameters, and the estimated formation stresses.

Abstract: Systems and methods for determining a formation property related to formation strength and stresses are disclosed. A method for determining a formation strength includes obtaining radial formation property measurements at different wellbore pressures; generating a radial stress profile based on a formation model; generating a radial stress function from the radial stress profile; and comparing the radial formation property measurements with the radial stress function to determine the formation strength. A method for determining a formation stress profile includes deriving formation parameters from a formation radial profiling; obtaining formation log data that comprise formation density data; estimating formation stresses from the formation log data; and deriving a radial stress profile based on a formation model, the derived formation parameters, and the estimated formation stresses.

Abstract: A method provides for locating and measuring mechanical damage in rock surrounding a borehole by detecting one or both of reductions in ultrasonic compressional wave velocity in the rock as a function of azimuth, and by detecting focused acoustic energy in the rock from local increases in ultrasonic compressional wave amplitude resulting from velocity gradients. A first preferred embodiment uses a combination of azimuthal ultrasonic compressional wave velocity data and azimuthal ultrasonic compressional wave energy data. A second embodiment uses azimuthal ultrasonic compressional wave velocity data and omni-directional sonic velocity data, with a comparison test or a curve fitting test. A third embodiment uses azimuthal ultrasonic compressional wave energy data.

Abstract: Apparatus and methods for determining an indication of a nonlinear property of a formation traversed by a borehole are provided. An acoustic tool is used in a borehole to generate first and second signals of different frequencies. As a result of nonlinearities in the formation, the mixing of the first and second signals results in a third signal having a frequency equal to the difference of the frequencies of the first and second signals. The amplitude of the third signal is measured by a detector, and the indication of nonlinearity of the formation is determined according to a relationship which relates the measured amplitude at the measured frequency to the amplitudes of the first and second signals, the frequency of measurement, the velocity of the measured wave, the distance of the receiver from the source, and a function of the nonlinear and linear parameters of the formation.

Abstract: An apparatus for reducing or eliminating the effects of a quadrupole component of an acoustic signal received from a transversely mounted acoustic source in a drill collar of a logging while drilling tool. The apparatus includes a drill collar for supporting a drill bit, a transversely mounted transmitter situated in a first horizontal plane in the drill collar which transmits acoustic energy into an earth formation. The drill collar also houses at least one receiver mounted in a second horizontal plane in the drill collar at an angular displacement from the transmitter such that the effects of a quadrupole component of the acoustic energy detected by the receiver are rendered insignificant.

Abstract: Apparatus and methods for the flow analysis of multiphase fluids including a liquid phase in a tubular conduit use Stoneley waves by exciting and detecting sonic wave energy in the tubular conduit. Information about the Stoneley mode component is obtained in one approach by using techniques that excite only the Stoneley mode together with certain other well behaved wave types, and then compensating for the latter. Alternatively the Stoneley arrival is specifically identified in the detected waveforms. Embodiments are described for: determining the flow rate of a liquid; detecting the presence or absence of gas in a liquid; determining the composition by volume of the dispersed phases in a multiphase fluid; determining the size distribution of bubbles in a multiphase fluid; and determining the velocity of slugs in a multiphase fluid.

Abstract: Techniques for a broad band high frequency acoustic investigation of a subsurface formation around a borehole are described utilizing a range of acoustic frequencies selected to produce detectable acoustic backscatter from grains within the subsurface formation. The acoustic backscatter is detected and a spectrum thereof is produced and averaged over adjacent subsurface formation regions. A subsurface formation parameter such as the frequency dependency of the attenuation of the backscatter is determined from an analysis of the spectrum to provide an indication of the granularity property of the subsurface formation. Use of a broad range of frequencies enables a determination of the subsurface formation parameter over a large range of grain sizes. In another technique the spectrum of the detected backscatter is modified to remove the effect of the frequency response of the system with which the investigation is made.