Abstract: An example method may include selecting a proposed pulse. A minimum phase wavelet may be generated based, at least in part, on the proposed pulse. A pulse signal within a wellbore may be generated based, at least in part, on the minimum phase wavelet.

Abstract: An apparatus and method may operate to mount acoustic sensors, azimuthally offset from each other, to the exterior of a casing. After the casing and acoustic sensors are in the borehole, signals are provided to the acoustic sensors to cause the acoustic sensors to emit acoustic signals into the annulus around the casing. The method further includes detecting reflected compression waves, shear waves or a combination or conversion thereof at the acoustic sensors to generate a set of two]way travel times of the acoustic signals. The method can further include generating distance measurements of a distance between corresponding acoustic sensors and points on the borehole wall based on the two]way travel times, to determine a position of the casing within the borehole. The method can further include identifying fluids based on the two]way travel times. Additional apparatus, systems, and methods are disclosed.

Abstract: Methods and systems for frequency-dependent fluid attenuation measurement are provided. In certain embodiments, the methods comprise: generating one or more reference acoustic signals within a reference fluid; receiving one or more reference acoustic signal reflections; determining a frequency-dependent response function based, at least in part, on the one or more reference acoustic signal reflections; generating one or more sample acoustic signals within a sample fluid; receiving one or more sample acoustic signal reflections; and determining a frequency-dependent attenuation function of the sample fluid based, at least in part, on the one or more sample acoustic signal reflections and the frequency-dependent response function.

Abstract: An example method may include transmitting a first acoustic signal from a downhole tool using a transmitter gain in a transmitter circuit. A first echo signal associated with the first acoustic signal may be received at the downhole tool using a receiver gain in a receiver circuit. At least one of the transmitter gain and the receiver gain may be adjusted based, at least in part, on the received first echo signal and at least one previously received echo signal.

Abstract: An example cement and casing evaluation tool includes an amplifier and a filter coupled an output of the amplifier. A transducer may be coupled to the output of the filter. A ringing reduction system may be coupled to at least one of the amplifier, the filter, and the transducer, wherein the ringing reduction system selectively dissipates energy from at least one of the amplifier, the filter, and the transducer in response to a control signal.

Abstract: In some embodiments, apparatus and systems, as well as method and articles, may operate to launch acoustic waves along a first acoustic path length from an acoustic transducer toward an axis of rotation, to impinge on a first front surface of a target substantially fixed with respect to the axis, and to receive a reflection of the acoustic waves from the first front surface at the acoustic transducer. After rotating the acoustic transducer about the axis along a substantially circular path, additional activities may include launching acoustic waves along a second acoustic path length, different from the first acoustic path length, from the acoustic transducer toward the axis to impinge on a second front surface of the target, and receiving a reflection of the acoustic waves from the second front surface at the acoustic transducer. Additional apparatus, systems, and methods are disclosed.

Abstract: An ultrasonic imaging method is provided. A wideband acoustic pulse is fired at a wall. A wideband response signal is received. The wideband response signal is processed to select an impedance measurement frequency. A wavelet having a characteristic frequency approximately equal to the impedance measurement frequency is fired. A wavelet response signal is received. A reflection coefficient is determined from the wavelet response signal. An impedance measurement is calculated from the reflection coefficient. Related tools and systems are also disclosed.

Abstract: Methods for evaluating cement bonding in a wellbore are provided. An example method for determining cement impedance includes generating one or more acoustic signals within a wellbore comprising a borehole fluid, a casing, and a cement layer. One or more reflections of the acoustic signals may be received from at least a portion of the wellbore, wherein each of the one or more reflections comprises an initial reflection portion and a resonance portion. At least one of the initial reflection portion and the resonance portion may be modified based, at least in part, on an attenuation response of the borehole fluid. An impedance of the cement layer may be determined by analyzing at least one of the modified initial reflection portion and the modified resonance portion.

Abstract: Apparatus, systems, and methods may operate to emit acoustic pulses into a drilling fluid in a well bore, using a first acoustic transducer in a downhole tool, and detecting the acoustic pulses after reflection from the wall of the well bore, using a second acoustic transducer in the downhole tool. The faces of the first and second acoustic transducers are non-parallel. Further activities include emitting additional acoustic pulses into the drilling fluid using the second acoustic transducer, and detecting them using the second acoustic transducer. The acoustic velocity of the drilling fluid can be determined based on respective travel times. Additional apparatus, systems, and methods are described.

Abstract: A system and method for effective estimation of properties of a formation using acoustic array processing is disclosed. An acoustic tool is directed to a zone of interest in the formation and generates a first signal. Real data corresponding to the first signal is then received. One or more basic parameters are provided as input. The basic parameters may include parameters relating to the acoustic tool or parameters relating to the zone of interest. A time semblance shear slowness and a frequency semblance shear slowness are determined using the basic parameters. A mask is then selected using the determined time semblance and frequency semblance shear slowness values and used to isolate a dispersion curve. A shear slowness value is selected from the dispersion curve and quality control is performed on the selected shear slowness value.

Abstract: A downhole cement plug includes a casing collar locator (CCL) operable to generate signals indicative of casing collars on a downhole casing string of a wellbore system; a controller communicably coupled to the CCL to output a plurality of distinct frequency signals based on the signals from the casing collar locator; and a signal generator communicably coupled to the controller to receive the plurality of distinct frequency signals from the controller and transmit the plurality of distinct frequency signals to a terranean surface through a portion of a wellbore system.

Abstract: Systems and methods of determining settlement characteristics of a drilling mud are disclosed. Conditions under which heavier elements of the drilling mud settle under the influence of gravity can be determined. Samples of drilling mud can be placed in testing cells, and ultrasonic test pulses can be transmitted through the samples. Responses to the test pulses can be detected and compared to other responses detected at different vertical positions within the testing cell. Settlement can be detected when the responses from different vertical positions are generally dissimilar. An environmental temperature of the testing cell can be changed over a testing time interval, and a settlement temperature can be determined by detecting a divergence in the responses from different vertical positions.

Abstract: A bender bar is presented. The bender bar includes at least two pairs of piezoelectric elements arranged on an inert element to adjust the response frequency of the bender bar. In some embodiments, the piezoelectric elements can be stacked on the inert element. In some embodiments, the piezoelectric elements are symmetrically arranged with respect to the bender bar such that a gap is formed between piezoelectric elements arranged on the inert element.

Abstract: An embodiment of a monitoring system for inspecting underground well structures includes a transmitter, a receiver, a processing module, and a power supply. The monitoring system is used to monitor pipe casings and structures surrounding the exterior of the pipe casings of a well. During operation, the transmitter directs time dependent energy radially towards a portion of a pipe casing, and the receiver measures energy that is returns to the system. The processing module amplifies, digitizes, and analyses the measurements of energy to produce monitoring information regarding the well structures.

Abstract: An acoustic transducer, such as a bender bar, having ferroelectric actuation elements that are designed to optimize a predetermined deflection mode shape.

Abstract: Systems, methods, and computer-readable storage devices for determining a location of an acoustic source outside of a borehole. The method relates to indicating a radial distance to the borehole, an offset along the borehole, and an azimuthal position around the borehole, of the acoustic source. The method includes receiving acoustic signals from respective acoustic sensors spaced along a tool lowered within the borehole. Using the acoustic signals and a borehole model, stacked energies are calculated for different radial distances from the borehole. At least one of the stacked energies is translated to an indication of a radial distance of the acoustic source from the borehole. The stacked energy for a radial distance is computed by offsetting the acoustic data signals in time in accordance the borehole model, summing the offset acoustic data signals to produce a stacked signal, and evaluating energy of the stacked signal over a time window.

Abstract: In some implementations, a method for validating an acoustic bond-log tool includes having a test fixture including a wellbore casing emulating tubing. An outer tubing emulates a well formation and forms a perimeter of an annulus surrounding the wellbore casing emulating tubing. The wellbore casing tubing is configured with a stepped outer surface emulating different wellbore casing sidewall thicknesses. A dividing structure is coupled in the axial direction to the outer surface of the wellbore casing emulating tubing and to the inner surface of the outer tubing to radially subdivide the annulus into a plurality of hermetically sealable sample sections. Each sample section contains a sample of a material having a known acoustic impedance. The acoustic bond-log tool is validated by comparing a bond-log tool measurement of the acoustic impedance of each sample in a particular sample section to the known acoustic impedance of the sample.

Abstract: A method of processing acoustic waveform data is disclosed. An acoustic logging tool acquires acoustic waveform data. An adaptive frequency filter is determined. The acoustic waveform data is filtered using the adaptive frequency filter. A formation slowness is determined from the filtered acoustic waveform data. The lower bound of the adaptive frequency filter may be determined using a polynomial function of a minimum excitement frequency parameter, a slowness parameter, and a third parameter. The upper bound of the adaptive frequency filter may be determined using a polynomial function of a peak excitement frequency parameter, the slowness parameter, and the third parameter.

Abstract: A bender bar transducer having stacked encapsulated actuators provides improved acoustic power over a wider frequency range, low applied voltage requirements and consistent part-to-part performance.

Abstract: A system to monitor the retrieval of a well tool from a wellbore comprises a deployment member coupled to the well tool to retrievably insert the well tool in the wellbore. At least one first identification transducer is coupled to a top end of the well tool to transmit an identification signal during retrieval of the well tool. At least one second identification transducer is located at at least one axial location along a surface pressure control assembly to detect the identification signal. A controller is in data communication with the at least one second identification transducer to determine the position of the well tool relative to the pressure control assembly, and to output at least one command related to the position of the well tool relative to the pressure control assembly.