Abstract: Oscillators that use resonator elements formed from langasite or one of its isomorphs are described herein. The resonator elements include crystal orientations that are stress and/or temperature compensated. The resonators vibrate at an oscillating frequency in a thickness-shear mode of vibration. The oscillating frequency can be used to derive temperature, derive pressure, and/or for frequency control applications.

Abstract: Systems and methods for identifying sanding in production wells using time-lapse sonic data. Formation anisotropy can be characterized in terms of shear moduli in a vertical wellbore, e.g., vertical shear moduli C44 and C55 in the wellbore axial planes and horizontal shear modulus C66 in the wellbore cross-sectional plane. Changes in formation anisotropy between different times can provide qualitative indicators of the occurrence of sanding in the production well. Before production begins, the horizontal shear modulus C66 is typically less than the vertical shear modulus C44 or C55 or both. At a subsequent time after sanding occurs, the horizontal shear modulus C66 is typically greater than the vertical shear modulus C44 or C55 or both. By comparing the shear moduli of the vertical wellbore at different times, it is possible to identify the occurrence of sanding in the production well using time-lapse sonic data.

Abstract: An apparatus and a method for recovering hydrocarbons from a subterranean formation including collecting baseline and subsequent sonic data. Either open or cased hole Stoneley and cross dipole dispersions are calculated using the baseline and subsequent sonic data, the minimum and maximum horizontal stress magnitudes are calculated using the calculating dispersions, a pressure is calculated and hydrocarbons are recovered.

Abstract: A technique facilitates determination of fracture attributes through the recording and analyzing of borehole sonic data before and after a fracturing operation. The technique comprises generating broadband acoustic waves at an array of receivers based on output from a plurality of acoustic sources. The waveforms of the broadband acoustic waves are recorded and processed to estimate sonic signatures. The sonic signatures are then used to determine fracture attributes. In some applications, the data may be used to determine whether the fractures in the formation are filled with fluid or soft sediments. Information on the fracture attributes is output to a suitable system, e.g. a computer display.

Abstract: Maximum and minimum horizontal stresses, and horizontal to overburden stress ratio, are estimated using radial profiles of shear moduli. Inversion enables estimation of maximum and minimum horizontal stresses using radial profiles of three shear moduli associated with an orthogonal set of axes defined by the three principal stress directions. Differences in the far-field shear moduli are inverted together with two difference equations obtained from the radial profiles of the dipole shear moduli C44 and C55, and borehole stresses in the near-wellbore region. The horizontal to overburden stress ratio is estimated using differences in the compressional, dipole shear, and Stoneley shear slownesses at two depths in the same lithology interval where the formation exhibits azimuthal isotropy in cross-dipole dispersions, implying that horizontal stresses are nearly the same at all azimuths.

Abstract: Apparatus and method for characterizing a barrier installed in a borehole traversing a formation including locating an acoustic tool with a receiver and a transmitter at a location in the borehole, activating the acoustic tool to form acoustic waveforms, wherein the receiver records the acoustic waveforms, and processing the waveforms to identify barrier parameters as a function of azimuth and depth along the borehole, wherein the waveforms comprise at least two of sonic signals, ultrasonic pulse-echo signals, and ultrasonic pitch-catch signals.

Abstract: Maximum and minimum horizontal stresses, and horizontal to overburden stress ratio, are estimated using radial profiles of shear moduli. Inversion enables estimation of maximum and minimum horizontal stresses using radial profiles of three shear moduli associated with an orthogonal set of axes defined by the three principal stress directions. Differences in the far-field shear moduli are inverted together with two difference equations obtained from the radial profiles of the dipole shear moduli C44 and C55, and borehole stresses in the near-wellbore region. The horizontal to overburden stress ratio is estimated using differences in the compressional, dipole shear, and Stoneley shear slownesses at two depths in the same lithology interval where the formation exhibits azimuthal isotropy in cross-dipole dispersions, implying that horizontal stresses are nearly the same at all azimuths.

Abstract: Methods and apparatus facilitating radial profiling of shear slowness are disclosed. According to some aspects of the invention, acoustic tool bias is accounted for in the calculation of radial profiles. According so some aspects, acoustic tool bias is accounted for by replacing acoustic tool structure with a resonance-impedance model. The resonance-impedance modeling according to principles of the present invention is applicable to vertical, deviated, and horizontal boreholes.

Abstract: Methods are disclosed for detecting fluid in at least one annulus around at least one casing installed in a borehole traversing a formation utilizing a sonic tool. The sonic tool is activated in the borehole and the received sonic waveforms are processed to obtain a dispersion plot. A reference dispersion plot is generated using a model of the borehole where the casing is well-bonded by cement. The obtained and reference dispersion plots are compared. An indication of fluid and in some cases, the specific radial location thereof is obtained based on the signature of the obtained plot as opposed to the reference plot. The methods are effective in doubly-cased boreholes using monopole and/or dipole sources.

Abstract: Systems and methods for identifying sanding in production wells using time-lapse sonic data. Formation anisotropy can be characterized in terms of shear moduli in a vertical wellbore, e.g., vertical shear moduli C44 and C55 in the wellbore axial planes and horizontal shear modulus C66 in the wellbore cross-sectional plane. Changes in formation anisotropy between different times can provide qualitative indicators of the occurrence of sanding in the production well. Before production begins, the horizontal shear modulus C66 is typically less than the vertical shear modulus C44 or C55 or both. At a subsequent time after sanding occurs, the horizontal shear modulus C66 is typically greater than the vertical shear modulus C44 or C55 or both. By comparing the shear moduli of the vertical wellbore at different times, it is possible to identify the occurrence of sanding in the production well using time-lapse sonic data.

Abstract: Systems and methods for the estimating a plurality of anisotropic elastic constants (Cij) using borehole dispersions and refracted compressional headwave velocity at a single logging depth in a vertical, deviated, or horizontal wellbore in a transversely-isotropic with a vertical axis of symmetry (“TIV”) formation. The estimated elastic constants can then be used to calculate near-wellbore stress distributions in the wellbore, which aids in an optimal completion design, such as for shale-gas production in the presence of shale heterogeneity.

Abstract: Cased-hole radial profiling of shear parameters from sonic measurements is disclosed.

Abstract: To determine properties of a subterranean structure, information relating to dipole compressional data is collected based on measurements by a logging tool in a borehole. The information relating to the dipole compressional data is analyzed in multiple dimensions (e.g., multiple borehole axial planes) to determine the properties of the subterranean structure through which the borehole extends.

Abstract: Methods and apparatus for modeling formations are disclosed. An example apparatus includes a source spaced from receivers. The source is to transmit a signal and the receivers are to receive at least a portion of the signal. The example apparatus also includes a processor to process waveform data associated with the signal by generating a parameter estimate used in an inversion of Stoneley dispersion to enable a Stoneley shear slowness to substantially correspond to a slow-shear slowness when the apparatus is at least partially positioned in a horizontal wellbore of a vertical transverse isotropy formation.

Abstract: A method and apparatus for assessing induced fractures in a subterranean formation including acquiring sonic data before and after a hydraulic fracturing operation, calculating a shear modulus in the borehole cross-sectional plane from Stoneley data, and calculating two shear moduli in two borehole orthogonal axial planes from cross dipole data. A method and apparatus for assessing induced fractures in a subterranean formation including collecting sonic data before and after fracturing the formation, calculating a far-field shear modulus in the borehole cross-sectional plane and a far-field shear moduli in the two orthogonal borehole axial planes, inferring the open or closed status of a fracture, and estimating a radial width or height or both of a vertical fracture.

Abstract: An apparatus and a method for recovering hydrocarbons from a subterranean formation including collecting baseline and subsequent sonic data, calculating either open or cased hole Stoneley and cross dipole dispersions using the baseline and subsequent sonic data, estimating the minimum and maximum horizontal stress magnitude using the calculating dispersions, calculating a pressure, and recovering hydrocarbons.

Abstract: A pressure transducer for high-pressure measurements comprising a housing and a piezoelectric resonator located in the housing, wherein the resonator comprises double rotation cut piezoelectric material configured or designed for vibrating in the fundamental tone of dual modes of the fast and slow thickness-shear vibrations.

Abstract: Methods and apparatus to process time series data for propagating signals in a subterranean formation are disclosed. An example method described herein for processing measured data comprises receiving a time series of measured data obtained by sensing a propagating signal, the propagating signal having passed through a subterranean formation, transforming the time series of measured data to generate a time-frequency representation of the time series, and processing the time-frequency representation to at least one of reduce noise in the time frequency representation, or enhance a component of the propagating signal present in the time-frequency representation.

Abstract: Methods and systems for analyzing subterranean formations in-situ stress are disclosed. A method for extracting geological horizon on-demand from a 3D seismic data set, comprises receiving sonic log data; computing the anisotropic shear moduli C44, C55 and C66; determining in-situ stress type and selecting an in-situ stress expression corresponding to the in-situ stress type; computing stress regime factor Q of the formation interval; and computing and outputting the maximum stress ?H by using the stress regime factor Q, Vertical stress ?v and Minimum horizontal stress ?h.

Abstract: Methods and apparatus facilitating measurement of anisotropy are disclosed. According to some aspects, anisotropy can be determined while drilling. Monopole/quadrupole interactions, as well as monitoring dipole excitations and other methods, may be used to find the principal shear directions of a formation while drilling or during wireline or other operations.