Abstract: A method for monitoring performance of an electric submersible pump. The method includes receiving data indicating a plurality of observable parameters from one or more sensors, generating a reduced set of components representative of at least some of the observable parameters and the reduced set having a dimensionality less than the plurality of observable parameters, identifying one or more components of the reduced set that captures a total variance of the plurality of observable parameters above a predetermined threshold, constructing at least one manifold of normal operation of the electric submersible pump in a reduced component space, receiving additional data from the sensors, transforming the additional data into the identified components establishing an electric submersible pump performance, and detecting whether a deviation of the electric submersible pump performance from a normal mode of operation of the electric submersible pump exceeds a predetermined threshold.

Abstract: Systems, methods, and apparatus to drive reactive loads are disclosed. An example apparatus to drive a reactive load includes a reactive component in circuit with the reactive load, a first switching element in circuit with the reactive load to selectively hold the reactive load in a first energy state and to selectively allow the reactive load to change from the first energy state to a second energy state, a second switching element in circuit with the reactive load to selectively hold the reactive load in the second energy state and to selectively allow the reactive load to change from the second energy state to the first energy state, and a controller to detect a current in the reactive load, and to control the first and second switching elements to hold the reactive load in the first or the second energy state when the current traverses a threshold.

Abstract: A technique includes receiving data representing time domain waveforms acquired by receivers of a drilling string-disposed acoustic measurement tool in response to energy emitted by at least one dipole source of the tool. The technique includes processing the data to determine slowness values associated with a plurality of acoustic modes, including a formation flexural acoustic mode and a tool flexural acoustic mode. The technique includes identifying slowness-frequency pairs from the slowness values and determining a shear slowness based at least in part on the identified slowness-frequency pairs.

Abstract: A technique includes receiving data acquired by an acoustic measurement tool in a well, where the data represents multiple acoustic modes, including a first order formation flexural acoustic mode and a higher order formation flexural acoustic mode. The technique includes processing the data to identify the higher order formation flexural acoustic mode; and determining a shear slowness based at least in part on slowness values that are associated with the identified higher order formation flexural acoustic mode.

Abstract: A downhole monitoring system and method that includes a sensor system with a sensor array with a number of sensors and a hub. Data measured by the sensors is processed by the hub and wirelessly communicated to a smart node. The sensor system may be mounted in the annulus formed between a borehole wall and an exterior surface of a well casing. The sensors may be configured to monitor the formation for microseismic events generated during hydraulic fracturing. The fracture growth and propagation may be monitored using the data obtained by the sensors. The data may facilitate real time control of the hydraulic fracturing operation.

Abstract: Apparatus and methods for characterizing the physical state of a barrier installed in a borehole traversing a formation including locating an ultrasonic tool with a plurality of spaced receivers and a transmitter at a location in the borehole, activating the ultrasonic tool to form ultrasonic waveforms, wherein the spaced receivers record the ultrasonic waveforms, aligning the transmitter and the spaced receivers, wherein the ultrasonic waveforms comprise propagated Lamb modes, processing the ultrasonic waveforms to obtain a first amplitude dispersion plot of attenuation as a function of frequency and first phase dispersion plot of phase velocity as a function of frequency, processing attenuation dispersions to identify discontinuities, and relating the discontinuities to barrier wavespeeds.

Abstract: A method for torsional wave logging in a borehole of a subterranean formation. The method includes obtaining a torsional wave measurement of the borehole, wherein the torsional wave measurement represents characteristics of a torsional wave propagating within a cylindrical layered structure associated with the borehole, wherein the cylindrical layered structure comprises the subterranean formation and a completion of the borehole, analyzing, by a computer processor, the torsional wave measurement to generate a quality measure of the completion, and displaying the quality measure of the completion.

Abstract: Methods and systems are provided for modeling an aspect of a hydrocarbon-containing reservoir by constructing a first factor graph having variables and factors that describe the aspect of the hydrocarbon-containing reservoir. The first factor graph is converted to a tree-structured graph that does not have any cycle or loops. The tree-structured graph is converted to a second factor graph that does not contain any cycles or loops, wherein the second factor graph has variables and factors that describe the aspect of the hydrocarbon-containing reservoir. A query on the second factor graph is carried out involving message passing operations that perform probabilistic inference on the second factor graph with regard to the aspect of the hydrocarbon-containing reservoir that is modeled by the second factor graph.

Abstract: A method for torsional wave logging in a borehole of a subterranean formation. The method includes obtaining a torsional wave measurement of the borehole, wherein the torsional wave measurement represents characteristics of a torsional wave propagating within a cylindrical layered structure associated with the borehole, wherein the cylindrical layered structure comprises the subterranean formation and a completion of the borehole, analyzing, by a computer processor, the torsional wave measurement to generate a quality measure of the completion, and displaying the quality measure of the completion.

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 fmal dispersion curve.

Abstract: Automatic detection and accurate time picking of weak events embedded in strong noise such as microseismicity induced by hydraulic fracturing is accomplished by: a noise reduction step to separate out the noise and estimate its spectrum; an events detection and confidence indicator step, in which a new statistical test is applied to detect which time windows contain coherent arrivals across components and sensors in the multicomponent array and to indicate the confidence in this detection; and a time-picking step to accurately estimate the time of onset of the arrivals detected above and measure the time delay across the array using a hybrid beamforming method incorporating the use of higher order statistics. In the context of hydraulic fracturing, this could enhance the coverage and mapping of the fractures while also enabling monitoring from the treatment well itself where there is usually much higher and spatially correlated noise.

Abstract: Techniques involve obtaining acoustic data from an acoustic logging tool, where the acoustic data includes waves reflected from the casing, the annular fill material, the formation, and/or interfaces between any of the casing, the annular fill material, and the formation. A crude casing thickness, tool position (e.g., eccentering), mud sound velocity may be estimated using the acoustic data.

Abstract: Techniques involve obtaining acoustic data from an acoustic logging tool, where the acoustic data includes waves reflected from the casing, the annular fill material, the formation, and/or interfaces between any of the casing, the annular fill material, and the formation. A crude casing thickness, tool position (e.g., eccentering), mud sound velocity may be estimated using the acoustic data. A specular reflection signal may also be estimated based on the acoustic data. A modeled waveform may be generated using the estimated specular reflection signal and one or more model parameters, such as an estimated crude casing thickness, an estimated tool position, an estimated sound velocity of mud between the acoustic logging tool and the casing, an estimated impedance of the annular fill material, and an estimated impedance of the mud. The modeled waveform may be calibrated in some embodiments.

Abstract: Apparatus and methods are provided. An ultrasonic tool with an array of axially spaced receivers and a transmitter is located in a borehole and is activated. Ultrasonic waveform indications recorded by the receivers are processed and analyzed to determine the presence of non-dispersive headwave signatures. If a non-dispersive headwave signature is located, the presence of a solid such as cement in the annulus is confirmed, and one or more of the compressional and shear velocities of the cement can be determined. If only casing dispersive mode signatures are found, the annulus is determined to possibly contain no cement at the location of interest and additional processing is required.

Abstract: A method, a system, and a computer readable medium for analyzing a wavelet within a seismic signal are described herein. The method includes receiving a seismic signal from a seismic receiver, such as a geophone, and using a Bayesian probability method to determine an associated arrival time for the wavelet and determine an uncertainty for the arrival time of the wavelet. The method has application in hydraulic fracturing monitoring operations and in spatially mapping fractures.

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: Embodiments of the disclosure may include systems and methods for estimating an acoustic property of an annulus in a cement evaluation system. In one embodiment, a casing arrival signal is acquired at acoustic receivers a cement evaluation tool. A spectral amplitude ratio is calculated based on the casing arrival signal. The spectral amplitude ratio is scanned to detect and identify discontinuities. If discontinuities are detected, the frequency at the discontinuity may be used to estimate a wavespeed of the annulus. If discontinuities are not detected, attenuation dispersions are calculated and estimated, and an estimated wavespeed and parameters are updated until the calculated and estimated attenuation dispersions match.

Abstract: Apparatus and methods for characterizing the physical state of a barrier installed in a borehole traversing a formation including locating an ultrasonic tool with a plurality of spaced receivers and a transmitter at a location in the borehole, activating the ultrasonic tool to form ultrasonic waveforms, wherein the spaced receivers record the ultrasonic waveforms, aligning the transmitter and the spaced receivers, wherein the ultrasonic waveforms comprise propagated Lamb modes, processing the ultrasonic waveforms to obtain a first amplitude dispersion plot of attenuation as a function of frequency and first phase dispersion plot of phase velocity as a function of frequency, processing attenuation dispersions to identify discontinuities, and relating the discontinuities to barrier wavespeeds.

Abstract: A method for torsional wave logging in a borehole of a subterranean formation. The method includes obtaining a torsional wave measurement of the borehole, wherein the torsional wave measurement represents characteristics of a torsional wave propagating within a cylindrical layered structure associated with the borehole, wherein the cylindrical layered structure comprises the subterranean formation and a completion of the borehole, analyzing, by a computer processor, the torsional wave measurement to generate a quality measure of the completion, and displaying the quality measure of the completion.

Abstract: Methods and apparatus for waveform processing are disclosed. An example method includes representing waveform data using space time propagators in the Discrete Radon Transform Domain. The method also includes identifying signals within the represented waveform data using a Sparisty Penalized Transform.