Abstract: Certain aspects and features relate to a system that includes a well tool configured to transmit an acoustic signal, detect a reflection signal, and transmit data representing the reflection signal. A processor analyzes the data to identify a pulse portion of the reflection signal, which is distinct from a reverberation portion. The processor determines a value for an attribute of the reflection signal, and executes a model to generate a first set of synthetic values for the attribute of the reflection signal and a second set of synthetic values for an impedance of a cement casing. The processor can then generate a lookup table that correlates the first set of synthetic values to the second set of synthetic values. By referencing the lookup table, processor can determine the impedance of the cement casing and alter a drilling plan or a completion plan based on the impedance of the cement casing.

Abstract: A method and system for removing intrinsic transducer noises. The method may comprise disposing a measurement assembly into a wellbore, performing a measurement operation at a depth in the wellbore with the measurement assembly to record two or more raw reflected waveforms, identifying one or more intrinsic transducer noises in the two or more raw reflected waveforms, dividing the two or more raw reflected waveforms into one or more subsections, and identifying one or more incoherent measurements in the one or more subsections. The method may further comprise deriving a noise model for each of the one or more incoherent measurements, performing an inversion for each noise model, and applying an adaptive subtraction to remove the one or more intrinsic transducer noises from the two or more raw reflected waveforms.

Abstract: A downhole sensor position adjustment device on a downhole sensor assembly comprising a set of centralizers and a sensor array coupled to an adjustable framework radially positionable by an actuator. The actuator includes an extend-retract mechanism to radially position the sensor array a predetermined radial distance to an inner surface of a casing. A controller communicatively coupled to the extend-retract mechanism is configured to actuate the extend-retract mechanism. A positioning sensor provides feedback of the predetermined radial distance of the sensor array to the inner surface of the casing.

Abstract: Certain aspects and features relate to a system that includes a well tool configured to transmit an acoustic signal, detect a reflection signal, and transmit data representing the reflection signal. A processor analyzes the data to identify a pulse portion of the reflection signal, which is distinct from a reverberation portion. The processor determines a value for an attribute of the reflection signal, and executes a model to generate a first set of synthetic values for the attribute of the reflection signal and a second set of synthetic values for an impedance of a cement casing. The processor can then generate a lookup table that correlates the first set of synthetic values to the second set of synthetic values. By referencing the lookup table, processor can determine the impedance of the cement casing and alter a drilling plan or a completion plan based on the impedance of the cement casing.

Abstract: An assembly for use in a wellbore can include a plurality of sensors positioned external to a casing string. The plurality of sensors can be positioned for detecting an amount of a hydrocarbon that is present in a fluid in the wellbore and a pH of the fluid in the wellbore. The plurality of sensors can be positioned for wirelessly transmitting signals representing the amount of the hydrocarbon that is present in the fluid and the pH of the fluid to a receiving device.

Abstract: A system and downhole tool comprising an ultrasonic transducer with a piezoelectric material embedded in a backing and a method of determining a parameter using the ultrasonic transducer. A self-noise of the transducer can be reduced by the piezoelectric material being at least partially embedded in the backing. The ultrasonic transducer can include an encapsulating material that encapsulates the backing.

Abstract: A method and system for receiving calibration information including a first power spectral density (PSD) value and a first sand concentration value at a particular frequency. Data is collected in a liquid flow at the particular frequency at a first depth in a downhole environment. A second power spectral density (PSD) value is then determined for the data in the liquid flow at the particular frequency. The second PSD value being compared with the first PSD value. Sand can also be determined to be present in the liquid flow when the second PSD value is greater than the first PSD value by a predefined threshold. A second sand concentration value of the sand present in the liquid flow being quantified based on the first sand concentration value.

Abstract: A method and system for determining cement bonding. The method may comprise disposing an acoustic logging tool in a wellbore, wherein the acoustic logging tool comprises a transmitter and a receiver, broadcasting a shaped signal with the transmitter such that fluid between concentric pipes disposed in the wellbore is excited, recording a reverberating signal with the receiver, processing the reverberating signal with an information handling system, and determining presence of a material outside an outermost of the concentric pipes. A well measurement system for determining cement bonding may comprise an acoustic logging tool. The acoustic logging tool may comprise at least one transmitter, wherein the at least one transmitter is configured to broadcast a shaped signal, and at least one receiver, wherein the at least one receiver is configured to record a reverberating signal. The acoustic logging tool may also comprise a conveyance and an information handling system.

Abstract: Disclosed are systems and methods for receiving, by at least one processor, calibration information comprising a first power spectral density (PSD) value and a first sand concentration value at a particular frequency, collecting, by at least one processor, data in a liquid flow at the particular frequency at a first depth in a downhole environment, determining, by the at least one processor, a second power spectral density (PSD) value for the data in the liquid flow at the particular frequency, comparing, by the at least one processor, the second PSD value with the first PSD value and determining that sand is present in the liquid flow when the second PSD value is greater than the first PSD value by a predefined threshold, and quantifying, by the at least one processor, a second sand concentration value of the sand present in the liquid flow based on the first sand concentration value.

Abstract: Systems, methods, and computer-readable media are provided for detecting sand in a production flow. An example method can include receiving acoustic field data generated by at least one acoustic sensor on a downhole tool lowered into a borehole of a production flow. The method can further include inputting the acoustic field data into an acoustic sand detection model and generating a sand flow signal based on output on the acoustic sand detection model.

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: A communication system that is positionable in a wellbore can include a first transceiver positioned externally to a casing string. The first transceiver can be operable to detect a presence or an absence of a surface wave; determine a location of a fluid in the wellbore based on the presence or the absence of the surface wave; and transmit data indicative of the location to a second transceiver. The surface wave can include an electromagnetic wave that has a magnetic field or an electric field that is non-transverse to a direction of propagation of the surface wave. The communication system can also include the second transceiver, which can be positioned externally the casing string and operable to receive the data.

Abstract: An assembly for use in a wellbore can include a plurality of sensors positioned external to a casing string. The plurality of sensors can be positioned for detecting an amount of a hydrocarbon that is present in a fluid in the wellbore and a pH of the fluid in the wellbore. The plurality of sensors can be positioned for wirelessly transmitting signals representing the amount of the hydrocarbon that is present in the fluid and the pH of the fluid to a receiving device.

Abstract: A method and system for determining cement bonding. The method may comprise disposing an acoustic logging tool in a wellbore, wherein the acoustic logging tool comprises a transmitter and a receiver, broadcasting a shaped signal with the transmitter such that fluid between concentric pipes disposed in the wellbore is excited, recording a reverberating signal with the receiver, processing the reverberating signal with an information handling system, and determining presence of a material outside an outermost of the concentric pipes. A well measurement system for determining cement bonding may comprise an acoustic logging tool. The acoustic logging tool may comprise at least one transmitter, wherein the at least one transmitter is configured to broadcast a shaped signal, and at least one receiver, wherein the at least one receiver is configured to record a reverberating signal. The acoustic logging tool may also comprise a conveyance and an information handling system.

Abstract: An assembly for use in a wellbore can include a plurality of sensors positioned external to a casing string. The plurality of sensors can be positioned for detecting an amount of a hydrocarbon that is present in a fluid in the wellbore and a pH of the fluid in the wellbore. The plurality of sensors can be positioned for wirelessly transmitting signals representing the amount of the hydrocarbon that is present in the fluid and the pH of the fluid to a receiving device.

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. An echo signal corresponding to the pulse signal from at least a portion of the wellbore may be received, wherein the echo signal is indicative of a wellbore property.

Abstract: An example casing and cement evaluation tool may include a tool body and a rotating portion coupled to the tool body. A first transducer may be coupled to the rotating portion at a radial offset from a longitudinal axis of the tool. A second transducer may be coupled to the rotating portion at a different radial offset from the longitudinal axis of the tool.

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: 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.