Abstract: Waves from cement bond logging with a sonic logging-while-drilling tool (LWD-CBL) are often contaminated with tool waves and may yield biased CBL amplitudes. The disclosed LWD-CBL wave processing corrects the first echo amplitudes of LWD-CBL before calculating the BI. The LWD-CBL wave processing calculates a tool wave amplitude and a phase angle difference as the difference of the phases between the tool waves and casing waves. The tool waves are then used to correct the LWD-CBL casing wave amplitude and remove errors introduced from tool waves. In conjunction with the sets of operations described, the LWD-CBL wave processing also include array preprocessing operations. Array preprocessing may employ variation of bandpass filtering and frequency-wavenumber (F-K) filtering operations to suppress tool wave.

Abstract: The present disclosure relates generally to signal comparison in seismic/acoustic imaging and data processing. In particular, this disclosure relates to a new nonlinear signal comparison (NLSC) approach which obtains a uniform resolution across a frequency band. The overall resolution in NLSC can be controlled over the frequency band by an adjustable parameter.

Abstract: Methods are provided for identifying a cementation status of a multi-string cased wellbore utilizing sonic tools with monopole and/or dipole transmitters and with an array of sonic receivers axially displaced from the transmitter(s). The sonic tool is used to record waveforms. The waveforms are then processed to generate slowness and/or attenuation dispersions. The slowness and/or attenuation dispersions are projected onto a slowness and/or attenuation axis, and the results are compared to a data set of projected slowness and/or attenuation dispersions representing a plurality of different multi-string cased wellbore cement status scenarios in order to select the scenario most closely associated with the results. The presence or lack of eccentering of a casing is similarly obtained where the data set includes projected dispersions representing properly centered and ec-centered casings.

Abstract: Production capability of cased hole perforations in a cased completed well lined with a casing in an under-pressured gas producing reservoir is tested. A sonde of a dipole shear or array sonic (full waveform) acoustic well logging tool is moved in a well bore of the cased completed well in the reservoir across a depth interval of interest, which covers cased hole perforations zones in the reservoir. The well logging sonde has in it an acoustic energy source and acoustic energy receivers. Responses are logged at depth intervals of interest to the transit of Stoneley waves along the casing walls from the acoustic energy source to the acoustic energy receivers. Measures of characteristics (e.g., travel time and attenuation) of the Stoneley wave are obtained. The responses are then processed to indicate production capability of the cased hole perforations.

Abstract: An embodiment of a method of estimating a property of an earth formation includes: disposing an acoustic tool in a borehole in an earth formation, the acoustic tool including an acoustic source and at least one acoustic receiver; transmitting acoustic signals into the borehole by the acoustic source, the acoustic signals having at least one linear guided wave mode that propagates along a surface of the borehole; receiving the acoustic signals by at least one receiver; analyzing, by a processor, the acoustic signals to measure non-linear harmonic waves generated by the formation is response to the at least one linear guided wave mode; and estimating a property of the formation based on the measured non-linear harmonic waves.

Abstract: An apparatus is provided for extracting slowness dispersion characteristics of sonic wave forms in broadband acoustic waves received by multiple sensors including means to digitize the sonic wave forms to form discrete time wave forms and converting the discrete time wave forms into frequency domain wave forms and means to divide a processing band of the wave forms into frequency sub-bands. For each sub-band approximating a family of candidate dispersion curves for multiple modes, parameterizing each of the curves by phase and group slowness, and forming a frequency dependent over-complete dictionary of basis elements, each corresponding to a pair of phase and group slownesses. In addition, forming multiple measurement vectors from the frequency domain data and implementing a sparse Bayesian learning (SBL) algorithm on the vectors with a block sparse signal model and outputting the results. Also, a means for generating a final dispersion curve.

Abstract: A system and method for measuring a formation property in a wellbore is disclosed. In the method, an acoustic measurement tool is introduced into a wellbore. The acoustic measurement tool may include a transmitter and a plurality of sensors. At least one of the plurality of sensors may be positioned in a non-uniform spacing configuration. The transmitter may transmit energy into the formation. The plurality of sensors may measure energy received from the formation. Additionally, a time semblance of the formation may be determined using at least one time semblance algorithm generalized for non-uniform sensor spacing.

Abstract: Methods and apparatus for determining slowness of wavefronts. An example apparatus includes one or more sources spaced from a receiver. The one or more sources are to transmit one or more signals and the receiver is to receive at least a portion of the one or more signals. The apparatus includes a processor to process waveform data associated with the one or more signals by stacking waveforms of the waveform data based on to linear moveout and sinusoidal moveout.

Abstract: The invention relates to a method and apparatus for measuring the spatial and velocity distribution of scattering structures of a sample in semi-transparent matter. The acquired spectral data I(k, t) are transformed in two steps to image data I(z, v). A Doppler shift is imposed on the light to a separate real and mirror images in the v space to suppress the complex ambiguity artifact.

Abstract: A system and method to determine a length of a fracture induced from a borehole are described. The method includes isolating a portion of the borehole, the portion of the borehole including an end of the fracture at the borehole wall, increasing fluid pressure in the portion of the borehole, deploying a low-frequency source in the portion of the borehole, and varying a frequency of the low-frequency source to generate resonance oscillations at a resonance frequency in the fracture. The method also includes determining the length of the fracture based on the resonance frequency.

Abstract: A system and method are disclosed for exploring a subsurface region that contains a target sector of interest. The method comprises providing information about the harmonic response for the target sector of interest and a seismic source. The method comprises controlling the seismic source to provide seismic waves in a narrowband selected on the basis of the information about the harmonic response for the target sector of interest. The method comprises activating the seismic source so as to introduce seismic waves into the subsurface sector and sensing reflections of the seismic waves at a seismic receiver.

Abstract: A system and a method includes generating a first signal at a first frequency; and a second signal at a second frequency. Respective sources are positioned within the borehole and controllable such that the signals intersect in an intersection volume outside the borehole. A receiver detects a difference signal returning to the borehole generated by a non-linear mixing process within the intersection volume, and records the detected signal and stores the detected signal in a storage device and records measurement parameters including a position of the first acoustic source, a position of the second acoustic source, a position of the receiver, elevation angle and azimuth angle of the first acoustic signal and elevation angle and azimuth angle of the second acoustic signal.

Abstract: A system and a method for investigating rock formations includes generating, by a first acoustic source, a first acoustic signal comprising a first plurality of pulses, each pulse including a first modulated signal at a central frequency; and generating, by a second acoustic source, a second acoustic signal comprising a second plurality of pulses. A receiver arranged within the borehole receives a detected signal including a signal being generated by a non-linear mixing process from the first-and-second acoustic signal in a non-linear mixing zone within the intersection volume. The method also includes-processing the received signal to extract the signal generated by the non-linear mixing process over noise or over signals generated by a linear interaction process, or both.

Abstract: Slowness dispersion characteristics of multiple possibly interfering signals in broadband acoustic waves as received by an array of two or more sensors are extracted without using a physical model. The problem of dispersion extraction is mapped to the problem of reconstructing signals having a sparse representation in an appropriately chosen over-complete dictionary of basis elements. A sparsity penalized signal reconstruction algorithm is described where the sparsity constraints are implemented by imposing a l1 norm type penalty. The candidate modes that are extracted are consolidated by means of a clustering algorithm to extract phase and group slowness estimates at a number of frequencies which are then used to reconstruct the desired dispersion curves. These estimates can be further refined by building time domain propagators when signals are known to be time compact, such as by using the continuous wavelet transform.

Abstract: A microseismic monitoring system includes a seismic sensor positioned proximate to a wellbore traversing a formation; an orientation source producing an orientation shot; a hydraulic apparatus operationally connected with the formation to produce a fracture in the formation; a computer control system operationally connected with a database of known spectral attributes for event categories; and a computer readable medium that carries instructions executable by the computer control system that, when executed: receive data from the seismic sensor; select an event of interest from the data received; determine a spectral estimate of the selected event of interest; compare the determined spectral estimate of the selected event of interest to the known spectral estimates; and select from the data received by the seismic source the orientation shot for orientation of the seismic sensor.

Abstract: Measurements of impedance are made using a piezoelectric transducer oriented at different angles to a formation bedding plane. The impedance measurements are then used to estimate the anisotropic velocity of the formation.

Abstract: In some aspects of the disclosure, a method and an apparatus is disclosed for investigating material surrounding the borehole.

Abstract: An apparatus for imaging an earth formation, the apparatus including: a logging instrument configured to be conveyed through a borehole penetrating the earth formation; a source of acoustic waves disposed at the logging instrument, wherein the source is configured to emit first acoustic waves having at least a first frequency and to enable intermodulation of the first acoustic waves in a medium having a nonlinear acoustic property resulting in generating new acoustic waves that are transmitted to the earth formation, the new acoustic waves having a new frequency different from the at least first frequency; and a receiver of acoustic waves configured to receive the new acoustic waves reflected from the earth formation, wherein the received new acoustic waves provide an image of the earth formation.

Abstract: In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency range and the second frequency, and wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.

Abstract: In some aspects of the disclosure, a method and an apparatus is disclosed for investigating material surrounding the borehole. The method includes generating within a borehole an intermittent low frequency vibration that propagates as a tube wave longitudinally to the borehole and induces a nonlinear response in one or more features in the material that are substantially perpendicular to a longitudinal axis of the borehole; generating within the borehole a sequence of high frequency pulses directed such that they travel longitudinally to the borehole within the surrounding material; and receiving, at one or more receivers positionable in the borehole, a signal that includes components from the low frequency vibration and the sequence of high frequency pulses during intermittent generation of the low frequency vibration, to investigate the material surrounding the borehole.

Abstract: In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed.

Abstract: In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency and the second frequency; and transmitting the collimated beam through a diverging acoustic lens to compensate for a refractive effect caused by the curvature of the borehole.

Abstract: A system and method are disclosed for exploring a subsurface region that contains a target sector of interest. The method comprises providing information about the harmonic response for the target sector of interest and a seismic source. The method comprises controlling the seismic source to provide seismic waves in a narrowband selected on the basis of the information about the harmonic response for the target sector of interest. The method comprises activating the seismic source so as to introduce seismic waves into the subsurface sector and sensing reflections of the seismic waves at a seismic receiver.

Abstract: Slowness dispersion characteristics of multiple possibly interfering signals in broadband acoustic waves as received by an array of two or more sensors are extracted without using a physical model. The problem of dispersion extraction is mapped to the problem of reconstructing signals having a sparse representation in an appropriately chosen over-complete dictionary of basis elements. A sparsity penalized signal reconstruction algorithm is described where the sparsity constraints are implemented by imposing a l1 norm type penalty. The candidate modes that are extracted are consolidated by means of a clustering algorithm to extract phase and group slowness estimates at a number of frequencies which are then used to reconstruct the desired dispersion curves. These estimates can be further refined by building time domain propagators when signals are known to be time compact, such as by using the continuous wavelet transform.

Abstract: In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed.

Abstract: Slowness dispersion characteristics of multiple possibly interfering signals in broadband acoustic waves as received by an array of two or more sensors are extracted without using a physical model. The problem of dispersion extraction is mapped to the problem of reconstructing signals having a sparse representation in an appropriately chosen over-complete dictionary of basis elements. A sparsity penalized signal reconstruction algorithm is described where the sparsity constraints are implemented by imposing a l1 norm type penalty. The candidate modes that are extracted are consolidated by means of a clustering algorithm to extract phase and group slowness estimates at a number of frequencies which are then used to reconstruct the desired dispersion curves. These estimates can be further refined by building time domain propagators when signals are known to be time compact, such as by using the continuous wavelet transform.

Abstract: In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

Abstract: In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

Abstract: A technique includes determining a magnitude and frequency distribution of seismic events attributable to hydraulic fracturing in a given stage of a well. The technique includes based on the determined magnitude and frequency distribution, predicting at least one additional magnitude and frequency distribution of seismic events attributable to hydraulic fracturing in at least one additional stage of the well. The technique includes determining at least one seismic property of a system of hydraulic fractures based at least in part on the determined additional magnitude and frequency distributions.

Abstract: In some aspects of the disclosure, a method and an apparatus is disclosed for investigating material surrounding the borehole.

Abstract: Multipole acoustic logging-while-drilling (LWD) tools and associated methods are disclosed herein. In some embodiments, the disclosed acoustic LWD tool comprises a transmitter array and at least one receiver array. The transmitter array generates acoustic waves with an excitation pattern having a cutoff frequency greater than about 3 kHz. The receiver array is spaced apart from the transmitter array and is configured to detect said acoustic waves. Some of the disclosed method embodiments comprise: generating multipole acoustic waves in a fluid-filled borehole using an excitation pattern with a cutoff frequency greater than about 3 kHz; selectively detecting acoustic waves that propagate with said excitation pattern; and determining an acoustic shear wave slowness for a formation penetrated by the borehole.

Abstract: A compact array of transducers is employed as a downhole instrument for acoustic investigation of the surrounding rock formation. The array is operable to generate simultaneously a first acoustic beam signal at a first frequency and a second acoustic beam signal at a second frequency different than the first frequency. These two signals can be oriented through an azimuthal rotation of the array and an inclination rotation using control of the relative phases of the signals from the transmitter elements or electromechanical linkage. Due to the non-linearity of the formation, the first and the second acoustic beam signal mix into the rock formation where they combine into a collimated third signal that propagates in the formation along the same direction than the first and second signals and has a frequency equal to the difference of the first and the second acoustic signals.

Abstract: An apparatus and method are disclosed for sensing a characteristic of a borehole. An exemplary apparatus includes a conductive pipe; an inlet, connected to the conductive pipe, for applying pulse to the conductive pipe; a resonant network device connected with the conductive pipe; and a transducer which is in operative communication with the resonant network device to measure a borehole characteristic, the transducer being configured to sense a modulated vibration frequency induced in the resonant network device when a pulse is applied to the inlet.

Abstract: An integrated framework is described for automating some or all of mud slowness estimation for both fast and slow formations. An estimation of fluid slowness based on monopole radial profiling is calculated if conditions permit. Alternatively, an estimation of fluid slowness based on Scholte wave slowness is estimated if conditions do not permit calculation based on monopole radial profiling. Tool standoff may also be estimated based on monopole radial profiling.

Abstract: Cross-dipole measurements are obtained in a borehole. By estimating a direction of polarization of the fast shear mode at low and high frequencies and comparing the estimated distances, a cause of anisotropy is established. Formation stresses and directions may be estimated.

Abstract: The method for exploring desired characteristics of a subsurface sector, having at least one resonant frequency, is based on selectively transmitting suitable narrowband energy waves into the subsurface sector, thereby producing narrowband signals reflected off the subsurface sector. The transmitted narrowband energy waves can be selectively and optimally adjusted in real time so as to provide optimum illumination of the desired characteristics from the explored sector.

Abstract: In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency and the second frequency; and transmitting the collimated beam through a diverging acoustic lens to compensate for a refractive effect caused by the curvature of the borehole.

Abstract: In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed.

Abstract: In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency range and the second frequency, and wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.

Abstract: A seismic energy source includes at least a first and a second acoustic radiator operatively coupled to a non-linear medium proximate an upper limit of formations in the Earth's subsurface. The first and second acoustic radiators are configured to convert electrical energy directly into acoustic energy. The source includes means for operating the first and the second acoustic radiator at respective first and second frequencies. The first and second frequencies are selected such that substantially no acoustic energy propagates through the non-linear medium. The first and the second frequencies are selected such that a difference therebetween is swept through a range of frequencies of seismic energy capable of propagating through the Earth's subsurface to at least one acoustic impedance boundary within the Earth's subsurface.

Abstract: In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

Abstract: In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

Abstract: A method and system model of the formation and rock matrices in a well site. A microseismic event from a hydraulic fracture in a well bore is recorded at a monitoring well site. The S-coda wave window of the microseismic event is identified. Q-factors for a set of frequencies within the S-coda wave window are then identified.

Abstract: Method for determining reservoir permeability from Stoneley wave attenuation extracted from conventional sonic logs by inversion of the full Biot wave equations for a porous medium. Frequency-dependent Stoneley-wave attenuation is extracted by analyzing array sonic measurements. Then, based on Biot's full theory applied to a borehole model and the standard logs (gamma ray, caliper, density, neutron, resistivity, sonic, etc.), a simulation model with the same parameters as the Stoneley-wave measurements is built. Next, a theoretical Stoneley-wave attenuation is computed for a given permeability. Finally, reservoir permeability is determined by comparing the modeled Stoneley-wave attenuation with the measured Stoneley-wave attenuation by an iterative inversion process.

Abstract: In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed.

Abstract: In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed.

Abstract: Methods are disclosed to predict pore pressure ahead of the drill bit while drilling a borehole through subsurface regions.

Abstract: A method of TI formation evaluation is disclosed. The method comprises receiving a plurality of borehole measurements; deriving a correlation between a first TI stiffness parameter and other TI stiffness parameters where the first and other TI stiffness parameters representing mechanical behavior of the TI formation; and computing the first and other TI stiffness parameters based on the borehole measurements and the derived correlation. The method further comprises evaluating TI formation elastic properties based on the computed first and other TI stiffness parameters. The method further comprises assuming that the shear modulus parallel to TI symmetric axis can be approximated from other moduli.

Abstract: A method is disclosed that may include separating modes in a plurality of coherent time-domain signals to form a plurality of separated modes, generating frequency coherence information for each of the plurality of separated modes, and combining the frequency coherence information for each of the plurality of separated modes to form combined frequency coherence information. An apparatus and system may include a processor and a storage device that can be encoded with computer-readable instructions, wherein the instructions when read and executed by the processor may include activities such as separating modes in a plurality of coherent time-domain signals, and recombining the modes in a frequency domain.

Abstract: Implementations of various techniques for a seismic inversion method. In one implementation, the method may include estimating a wavelet of a recorded seismic trace at a well location, transforming the recorded seismic trace to a relative seismic impedance trace, estimating a low frequency model trace using the relative seismic impedance trace and adding the low frequency model trace to the relative seismic impedance trace to generate an absolute trace.