Abstract: A method of evaluating a formation of interest, comprises collecting a data set comprising signals received at a plurality of receivers signals from a source on a bottom-hole assembly at a position in a borehole, processing the data set so as to create a virtual trace received at a virtual receiver located at the source position, and using the virtual trace to generate an image or measurement containing information about the formation of interest. The source may or may not be a drill bit and the data can be collected at several different source positions.

Abstract: Methods and related systems are described relating to processing subsurface sonic and seismic data. The described techniques use anisotropy estimates derived from a walkaway VSP to calibrate elastic properties derived from sonic logs. An empirical relationship between the sonic derived anisotropy parameters is modified until the upscaled elastic properties from the sonic log data best matches the anisotropy parameters measured with the walkway VSP. The result is a set of elastic constants consistent with the walkaway VSP measurements.

Abstract: A downhole tool for subsurface disposal is provided. The tool comprises an elongated tool body, an enclosure attached to an exterior surface of the tool body. The enclosure comprises at least one transducer disposed at an angle with respect to a longitudinal axis of the enclosure, and an electronics board coupled to and disposed adjacent to the at least one transducer. The enclosure also defines an internal cavity, and the internal cavity contains a fluid for insulating the at least one transducer from a downhole environment. The fluid is in direct contact with the at least one transducer and the electronics board.

Abstract: The present disclosure relates to methods and apparatuses for evaluating a porous earth formation. The method may include: generating an acoustic wave in a borehole fluid; measuring an attenuation of the acoustic wave; and estimating a permeability of an earth formation acoustically coupled to the borehole fluid using the estimated attenuation and a theoretical attenuation. The method may also include estimating a theoretical attenuation for the borehole fluid using acoustic properties of the borehole fluid. The apparatus for performing the method may include: an acoustic source, an acoustic sensor, and a processor configured to estimate the attenuation of an acoustic wave generated by the acoustic source.

Abstract: An ultrasonic scanner tool employs a transducer that excites a target plate at a known distance from the transducer. One side of the target plate forms a chamber that in operation is filled with wellbore fluid. On the other side of the target plate, a chamber is formed containing a vacuum or a fluid with a significantly lower acoustic impedance than the wellbore fluid and the target plate, allowing an improved measurement of the acoustic impedance of the wellbore fluid.

Abstract: Downhole cables are described that are configured to protect internal structures that may be detrimentally impacted by exposure to the downhole environment, by protecting such structures by at least two protective layers. In some examples, the structures to be protected may be housed in a protective tube housed within the protective outer sheath. The described configuration enables the use of structures such as polymer fibers in the cables for strength and load-bearing capability by protecting the fibers, by multiple protective layers, from exposure to gases or fluids within a wellbore.

Abstract: A shear wave is generated at a borehole wall. A static magnetic field is applied with a radial direction and an oscillating magnetic field is applied tangential to the borehole wall. The frequency of the oscillating field is varied until a resonance condition occurs. Motion of the formation under resonance provides an indication of a resistivity property of the earth formation.

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 for fracture characterization of unconventional formations are provided. Synthetic seismic fracture responses can be generated based on the derived fracture parameters. The synthetic seismic fracture responses may then be used to derive optimum seismic data acquisition geometry for fracture characterization. These methods of determining the seismic data acquisition geometry are advantageous over conventional methods in that these methods are more reliable and cheaper than existing empirical methods, particularly as applied to fractured unconventional formations. Moreover, these methods allow fracture parameters to be derived from limited but common well log data. Certain embodiments additionally contemplate determining the presence of gas filled fractures. These characterizations and evaluations of unconventional formations are useful for, among other things, determining optimal producing intervals and optimal drilling locations. These methods can eliminate the use of costly image logs and core data.

Abstract: Disclosed is a method for estimating a property of an earth formation penetrated by a borehole. The method includes: transmitting acoustic waves into the formation from an acoustic source disposed in the borehole and away from a wall of the borehole; generating radial acoustic eigenwaves within a space between the wall of the borehole and the acoustic source using the transmitted acoustic waves; receiving an acoustic signal with an acoustic receiver disposed at the wall of the borehole; sensing an electric field signal with an electric field sensor disposed at the wall of the borehole; and estimating the property using the received acoustic signal and the sensed electric field signal.

Abstract: An enclosure for housing a transducer and electronics for disposal on a downhole tool. A transducer is disposed at an angle with respect to a longitudinal axis of the enclosure, wherein the enclosure contains a fluid surrounding the transducer. Enclosures also include transducers linked to motor means for selective rotation of the transducers within the enclosure. Enclosures with transducer arrays for phased or targeted signal transmission/detection.

Abstract: A method of logging a perforation tunnel and associated features of the perforation tunnel can include the following features. A logging device including an ultrasonic transducer is located downhole into a well. The well has a casing. The ultrasonic transducer has a focal point that is a distance from the ultrasonic transducer so as to be behind the inner face of the casing. An ultrasonic signal is projected from the ultrasonic transducer. A reflection of the ultrasonic signal is reflected from an internal portion of the perforation tunnel, the perforation tunnel extending through the casing and into formation. A transit time is measured between transmission and reception of the ultrasonic signal. A position of the ultrasonic transducer corresponding to the ultrasonic transmission and reception of the reflected signal is determined.

Abstract: An apparatus, method and compute-readable medium for detecting a gas influx event in a borehole fluid during a drilling operation is disclosed. A measurement of an acoustic velocity of the borehole fluid is obtained at an acoustic sensor disposed in a borehole. A measurement of temperature of the borehole fluid is obtained at a temperature sensor disposed in the borehole. A process compares the measurement of the acoustic velocity of the borehole fluid to the measurement of the temperature of the borehole fluid to detect the gas influx event.

Abstract: Methods and apparatus to filter acoustic waveforms in downhole environments are described. An example method involves receiving acoustic waveform data representing acoustic signals traversing at least a portion of a borehole adjacent a subterranean formation and performing a direct transform operation on the acoustic waveform data to generate wavelet map data. The wavelet map data comprises a time-frequency representation of the acoustic waveform data.

Abstract: A system for measuring an acoustic property of material penetrated by a well borehole. The system uses a borehole logging tool comprising preferably one acoustic transmitter and preferably a plurality of acoustic receivers. An independent measurement is used to determine azimuthal orientation of the tool within the borehole. Firings of the transmitter are based upon azimuthal orientation of the tool. Receiver responses resulting from preferably a plurality of transmitter firings per tool revolution are combined to form at least one composite transmitter response. The composite receiver response is compensated for adverse effects of the tool operating eccentered within the borehole.

Abstract: Methods and systems are provided for performing acoustic sensing by utilizing distributed acoustic sensing (DAS) along a length of a conduit, such that the sensing is performed with the functional equivalent of tens, hundreds, or thousands of sensors. Utilizing DAS in this manner may cut down the time in performing acoustic sensing, which, therefore, may make acoustic sensing more practical and cost effective and may enable applications that were previously cost prohibitive with discrete acoustic sensors.

Abstract: A method of evaluating a cased borehole in an earth formation includes: emitting at least one acoustic signal into the borehole via an acoustic source and detecting a return acoustic signal via an acoustic sensor, the borehole including a casing and a casing support material disposed between the casing and a borehole wall; emitting a neutron flux via a neutron source into the borehole and detecting a radiation signal via a radiation detector, the radiation signal including induced gamma radiation resulting from neutron interactions; and identifying a casing support material characteristic based on the return acoustic signal and the radiation signal.

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: Casing signals generated by an EMAT in a borehole are processed using at least two orthogonal band-limited filters. The band-limited filters may include Gaussian or Cauchy Wavelet filters. By using the Hilbert transform, an envelope of the filtered signals is determined and amplitudes and arrival times of individual arrivals are estimated. These can be used to estimate casing and cement properties.

Abstract: Wellbore tracking by developing a wellbore deviation survey, including collecting wellbore deformation data using a caliper at each of a plurality of depths within the wellbore, collecting wellbore deviation data using a tiltmeter at ones of the plurality of depths, determining simulated wellbore deformation and deviation data using the oriented wellbore deformation data, and developing a wellbore deviation survey by calibrating the wellbore deviation data based on the oriented wellbore deviation data.

Abstract: One or more acoustic transducers are used to measure ultrasonic velocities in the mud in the interior channel of a drill collar. Corrections may be applied for temperature and/or fine grain drill cuttings to get the ultrasonic velocity in the annulus between the drill collar and the borehole wall. The latter velocity may be used for caliper measurements and for correcting measurements made by formation evaluation sensors.

Abstract: A method for making acoustic logging measurements includes grouping received acoustic waveforms into one of a plurality of groups, each group being representative of a measured borehole condition (e.g., a range of measured standoff values and/or a range of measured azimuth angles). The waveforms stored in at least one of the groups are stacked so as to obtain an averaged waveform. The averaged waveform may be further processed, for example, via a semblance algorithm to obtain at least one acoustic wave slowness.

Abstract: The present disclosure is related to apparatuses and methods for estimating borehole parameters using a plurality of reflections caused by a plurality of acoustic pulses. The reflections may overlap each other and/or the acoustic pulses. The methods may include estimating an envelope of the received acoustic signal at the at least one element of the array of transducers; and estimating at least one arrival time of at least one of the plurality of overlapping events from the envelope of the received acoustic signals, the arrival times being characteristic of the geometry of the borehole. The method may also include imaging the borehole wall. The apparatus may include an array of transducers on a rotatable transducer assembly with at least one element on the array configured to generate a plurality of acoustic pulses and receive reflections and a processor configured to perform the method.

Abstract: A method for characterizing fluid pumping effects on a subsurface formation includes (a) during pumping of fluid into the subsurface formation, detecting passive seismic signals related to fractures created in the subsurface formation. (b) A place of origin of the passive seismic signals is determined. (c) A seismic energy source is actuated for a plurality of actuations and an output thereof is beam steered toward the place of origin. (d) At least one acoustic property is determined for the place of origin using signals detected as a result of the plurality of actuations. The detected signals are beam steered toward the place of origin and are stacked over the plurality of actuations. (a), (b), (c) and (d) are repeated until the pumping is completed.

Abstract: A method for identifying gas in a wellbore includes imparting acoustic energy into the wellbore at a first selected position and detecting the acoustic energy at a second position in the wellbore spaced apart from the first position. Acoustic velocity of fluid in the wellbore from the detected acoustic energy. Presence of gas in the fluid is determined from the velocity.

Abstract: Methods and apparatus for performing sonic well logging within a wellbore based on optical Distributed Acoustic Sensing (DAS) are provided. A sonic well logging system based on DAS may be capable of producing the functional equivalent of tens, hundreds, or even thousands of acoustic sensors. In this manner, the emplacement of the sonic well logging system based on DAS may not be nearly as complex or expensive as emplacing a sonic well logging system based on traditional methods. Furthermore, multiplexing may be simpler, downhole electronics need not be used, and the sonic well logging system may be used in extreme, high temperature environments.

Abstract: Measurements of acoustic velocities are made through a case borehole in the absence and presence of an applied magnetic field. A formation resistivity parameter may be estimated from differences in the acoustic velocities.

Abstract: Methods and apparatus to identify layer boundaries in subterranean formations are described. An example method of identifying a layer boundary of a subterranean formation includes transmitting an acoustic signal from a transmitter into a borehole of the subterranean formation and receiving the acoustic signal at a receiver coupled to the downhole tool and spaced from the transmitter. Additionally, the example method includes logging an energy value associated with the acoustic signal received by the receiver as the downhole tool is moved in the borehole and identifying a change in the logged energy value associated with an impedance change in the subterranean formation to identify the layer boundary.

Abstract: In a method for logging the location of a fluid depth in a wellbore, an acoustic event is allowed to take place in a specific manner at the ground surface. This acoustic event generates pressure waves. The pressure waves travel in the wellbore downward. The pressure waves traveling in the wellbore are reflected at least also at the fluid depth. At the ground surface, the pressure waves traveling there out of the wellbore are picked up and the time of travel since the acoustic event is measured. The picked-up and measured pressure waves are analyzed and, together with the associated time of travel, the location of the fluid depth is deduced. The acoustic event generates a signal pattern having a predetermined, time-variable frequency spectrum. The signal pattern is emitted as vibration event into the wellbore, travels downward, and is reflected. At the ground surface, the picked-up signals originating from the wellbore are analyzed.

Abstract: In one aspect, the disclosure provides an apparatus that includes an acoustic transducer, and a backing coupled to the transducer, wherein the backing includes solid grains with fluid between the grains.

Abstract: The disclosure, in one aspect, provides an apparatus that includes an acoustic transducer and a backing in contact with a side of the transducer. The backing includes substantially unidirectional fibers in a matrix of a material that has high shear wave acoustic attenuation. The fibers contact the side of the transducer at an angle configured to convert substantially all of the compressional waves that enter the backing for the transducer into shear waves, which shear waves are then attenuated by the matrix of the backing material.

Abstract: A method for detecting fluid ingress in a wellbore, and if detected, obtaining an indication of where along said wellbore said fluid ingress is occurring. Acoustic sensing means, adapted to sense individual acoustic signals from a plurality of corresponding locations along said wellbore, are analyzed to determine if there exists a common acoustic component in acoustic signals generated from proximate locations in said wellbore. If so, the acoustic signal having the common acoustic component which appears earliest in phase, by virtue of such acoustic signal's corresponding location in the wellbore, determines the location in the wellbore of likely fluid ingress. In a preferred embodiment the acoustic sensing means comprises a fibre optic cable extending substantially the length of the wellbore, or alternatively a plurality of microphones situated at various locations along the wellbore comprising substantially the length of the wellbore.

Abstract: This disclosure relates in general to a method and system for acoustic monitoring using a fibre optic cable. More specifically, but not by way of limitation, embodiments of the present invention provide for using an optical fiber as a distributed interferometer that may be used to monitor a conduit, wellbore or reservoir. In certain aspects, the distributed interferometric monitoring provides for accurate detection of acoustic occurrences along the fibre optic cable and these acoustic occurrences may include fluid flow in a pipeline or wellbore, processes taking place in a wellbore or pipeline, fracturing, gravel packing, production logging and/or the like.

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: Acoustic waves from a controllable downhole acoustic source in a cased borehole are focused into a region of an earth formation. A hydrophone is used to monitor acoustic signals for onset of cavitation. The estimated pressure from the source in the focus region provides an estimate of formation pore pressure.

Abstract: A system and method for micro seismic fracture mapping using seismic source timing measurements for velocity calibration (28) and mapping. The system is deployed and coupled to a wire line (36) and a seismic source trigger with the sensor and transmitter coupled to the sensor with transmission of the time value of the first signal and the receiver and micro seismic velocity analyzer using receiving and transmitting of the first signal and the receiving and transmitting of the second signal transmitted to the analyzer (28) and the micro seismic velocity is calibrated based on the time difference between the first time value and a second time value associated with the second signal.

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: Channel estimation and signal equalization is used in a mud-pulse telemetry system for uplink communication during drilling of wellbores.

Abstract: A method for determining position of a wellbore in the Earth's subsurface includes actuating a plurality of seismic energy sources each disposed at a known geodetic position. Seismic energy from the sources is detected at a selected location along the wellbore. The geodetic position at the selected location is determined from the detected seismic energy. A corresponding method includes actuating a seismic energy source at a selected position within the wellbore. The seismic energy is detected at a plurality of known geodetic positions. The geodetic position of the source is determined from the detected seismic energy.

Abstract: The method disclosed is useful for estimating anisotropic properties of an earth formation. The method includes extracting travel time values of components of the acoustic wave induced from a downhole tool and reflected from a boundary bed formation. The method further includes obtaining a travel time ratio of the wave components and using the travel time ratio to estimate the anisotropic properties of the formation.

Abstract: Systems and methods for subterranean imaging and logging are herein disclosed. In one embodiment, a subterranean tool for logging and imaging a subterranean well is provided. The subterranean tool includes a tool body, at least one transducer arranged within the tool body and an acoustic window coupled to the transducer.

Abstract: A measurement package for disposal on an apparatus such as a downhole tool or a tool like device. The measurement package including an enclosure, a first acoustic transducer housed within the enclosure, a second acoustic transducer housed within the enclosure and electronics housed within the enclosure that is in communication with the first and second transducers. Further, an acoustic transmitter and receivers can be disposed at an angle with respect to a longitudinal axis of the enclosure. The enclosure can contain attenuative material surrounding the transmitter and receivers, and electronics for controlling the transmitter and receivers and communicating with the downhole tool.

Abstract: A method for initializing the input of each of m receiver channels of a receiving transducer in a well logging tool comprising the steps of selecting a logging tool having a multi-element receiving transducer wherein each element of the multi-element receiving transducer operates in an anti-resonant mode below its resonant frequency, and executing a routine in an initialization mode wherein a predetermined number of run cycles are operated and receiver input responses are measured and averaged for each of the m channels while transmitter firing signals are disabled.

Abstract: Passive suppression of casing signals is used to improve the ability to measure formation velocities. Passive suppression includes the use of a magnet slidably coupled to the casing.

Abstract: An acoustic logging system that measures distribution of foam cement and other material in a casing-borehole annulus. The distribution is preferably displayed as map. A borehole tool utilizes at least one acoustic transducer with a known frequency response and mounted on a rotating scanning head that is pointed essentially perpendicular to the borehole wall. The response of the transducer is used to measure an original impedance map of material within the borehole-casing annulus. A fast Fourier transform is used to generate a FFT map from the data comprising the original impedance map. The original impedance map is then combined with the FFT map using logic rules to obtain a final impedance map that is indicative of material within the casing-borehole annulus.

Abstract: A system, method and computer-readable medium for acquiring seismic data, which includes activating a seismic source at a surface location; defining a seismic trace of a seismic wave received at a downhole location on a bottomhole assembly in a borehole in response to the activation of the seismic source; compressing the seismic trace; and recording the compressed seismic trace to a storage medium.

Abstract: Measurements made by a transducer assembly for downhole imaging are affected by reverberations between the transducer and the window on the outside of the assembly. The reverberations result in a stationary noise on the image. Hardware solutions to improve signal-to-noise ratio includes using a composite transducer, adjusting the distance between the transducer and the window. SNR can also be improved by processing techniques that include stacking, fitting a sinusoid to the reverberation, by envelope peak detection, and by applying a notch filter.

Abstract: A method and apparatus for deploying seismic detectors and monitoring seismic activity associated with a production well from a down hole location within a well.

Abstract: Method for identifying one or more fracture clusters in a formation surrounding a reservoir. In one implementation, the method may include generating a P to S image, comparing the P to S image to one or more images from a borehole, and identifying one or more fracture clusters using the P to S image and the borehole images.

Abstract: An apparatus for evaluating a tubular in a borehole of includes at least two electromagnetic acoustic transducers. The transducers are configured to generate and receive first and second acoustic waves in the tubular. A difference in velocity of the two acoustic waves is indicative of a stress field in the tubular.