Abstract: An acoustic transceiver assembly including a housing, an oscillator, and at least one membrane. The housing has at least one inner wall defining a cavity. The housing also has a first end and a second end defining an axis of the acoustic transceiver assembly. The oscillator is provided in the cavity. The oscillator is provided with a transducer element, and a backing mass acoustically coupled to the transducer element. The at least one membrane extends outward from the backing mass to support at least the backing mass within the cavity. The at least one membrane is flexible in an axial direction parallel to the axis of the acoustic transceiver assembly to permit the backing mass to oscillate in the axial direction, and rigid in a transverse direction to restrict lateral movement of the backing mass relative to the housing.

Abstract: Systems and methods for cement evaluation by determining a shear velocity of a shear wave (26) propagating within a medium (20) located between a formation (12) and a casing (13) in a borehole (11) are presented. The method can include positioning an ultrasonic transducer array (21) in the borehole inside the casing. The method can also include in a pushing mode, generating a shear wave in the medium with the ultrasonic transducer array inside the casing. The method can also include in an interrogation mode, measuring a shear velocity of the shear wave in the medium with the ultrasonic transducer array. The shear velocity may be used to determine whether the medium is solid or liquid.

Abstract: An acoustic logging tool emits a wideband acoustic pulse toward an inside surface of a borehole casing and an acoustic response is received. The acoustic response is analyzed at one or more higher order harmonics of the thickness mode resonance of the casing to determine the acoustic impedance of the material behind the casing.

Abstract: A subsea installation kit is described. The kit is provided with a subsea tree, a plurality of tubing sections, a plurality of acoustic repeaters and a mechanical filter. The subsea tree is configured to be coupled to a subsea well having a wellbore. The tubing sections are configured to be connected together to form a tubing string extending from above the tree into the wellbore. The acoustic repeaters are configured to be attached to the tubing string in a spaced apart manner. One of the acoustic repeaters is a last acoustic repeater configured to be attached to the tubing string within or above the tree. The mechanical filter is configured to be connected into the tubing string and form a part of the tubing string above the last acoustic repeater, the mechanical filter configured to cause an attenuation to acoustic signals propagating in the tubing string above the tree.

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: Systems and methods for cement evaluation by determining a shear velocity of a shear wave (26) propagating within a medium (20) located between a formation (12) and a casing (13) in a borehole (11) are presented. The method can include positioning an ultrasonic transducer array (21) in the borehole inside the casing. The method can also include in a pushing mode, generating a shear wave in the medium with the ultrasonic transducer array inside the casing. The method can also include in an interrogation mode, measuring a shear velocity of the shear wave in the medium with the ultrasonic transducer array. The shear velocity may be used to determine whether the medium is solid or liquid.

Abstract: An acoustic transceiver assembly including a housing, an oscillator, and at least one membrane. The housing has at least one inner wall defining a cavity. The housing also has a first end and a second end defining an axis of the acoustic transceiver assembly. The oscillator is provided in the cavity. The oscillator is provided with a transducer element, and a backing mass acoustically coupled to the transducer element. The at least one membrane extends outward from the backing mass to support at least the backing mass within the cavity. The at least one membrane is flexible in an axial direction parallel to the axis of the acoustic transceiver assembly to permit the backing mass to oscillate in the axial direction, and rigid in a transverse direction to restrict lateral movement of the backing mass relative to the housing.

Abstract: An acoustic logging tool emits a wideband acoustic pulse toward an inside surface of a borehole casing and an acoustic response is received. The acoustic response is analyzed at one or more higher order harmonics of the thickness mode resonance of the casing to determine the acoustic impedance of the material behind the casing.

Abstract: A subsea installation kit is described. The kit is provided with a subsea tree, a plurality of tubing sections, a plurality of acoustic repeaters and a mechanical filter. The subsea tree is configured to be coupled to a subsea well having a wellbore. The tubing sections are configured to be connected together to form a tubing string extending from above the tree into the wellbore. The acoustic repeaters are configured to be attached to the tubing string in a spaced apart manner. One of the acoustic repeaters is a last acoustic repeater configured to be attached to the tubing string within or above the tree. The mechanical filter is configured to be connected into the tubing string and form a part of the tubing string above the last acoustic repeater, the mechanical filter configured to cause an attenuation to acoustic signals propagating in the tubing string above the tree.

Abstract: An acoustic logging tool emits a wideband acoustic pulse toward an inside surface of a borehole casing and an acoustic response is received. The acoustic response is analyzed at one or more higher order harmonics of the thickness mode resonance of the casing to determine the acoustic impedance of the material behind the casing.

Abstract: An acoustic transceiver assembly including a housing, an oscillator, and at least one membrane. The housing has at least one inner wall defining a cavity. The housing also has a first end and a second end defining an axis of the acoustic transceiver assembly. The oscillator is provided in the cavity. The oscillator is provided with a transducer element, and a backing mass acoustically coupled to the transducer element. The at least one membrane extends outward from the backing mass to support at least the backing mass within the cavity. The at least one membrane is flexible in an axial direction parallel to the axis of the acoustic transceiver assembly to permit the backing mass to oscillate in the axial direction, and rigid in a transverse direction to restrict lateral movement of the backing mass relative to the housing.

Abstract: An influx of gas into a borehole can be detected by deploying a string of acoustic sensors along a drill string or other conduit to monitor an acoustic characteristic, such as velocity or attenuation, of the drilling fluid present in the borehole. In response to detection of acoustic pulses propagating in the drilling fluid, the acoustic sensors generate signals that are representative of acoustic characteristics if the drilling fluid. Based on the generated signals, a data acquisition system can determine whether a change in the monitored acoustic characteristic is indicative of a gas influx.

Abstract: A bi-directional acoustic telemetry system is presented for communicating data and/or control signals between a first modem and a second modem along tubing. The system includes a communication channel defined by the tubing, a transducer of the first modem, and a transducer of the second modem. The transducer of each modem are configured to transmit and receive data and/or control signals, and are further configured to electrically communicate with a power amplifier characterized by an output impedance Zs and a signal conditioning amplifier characterized by an input impedance Zr. The system also includes a reciprocal response along the communication channel between the output impedance Zs and the input impedance Zr.

Abstract: An acoustic logging tool emits a wideband acoustic pulse toward an inside surface of a borehole casing and an acoustic response is received. The acoustic response is analyzed at one or more higher order harmonics of the thickness mode resonance of the casing to determine the acoustic impedance of the material behind the casing.

Abstract: An influx of gas into a borehole can be detected by deploying a string of acoustic sensors along a drill string or other conduit to monitor an acoustic characteristic, such as velocity or attenuation, of the drilling fluid present in the borehole. In response to detection of acoustic pulses propagating in the drilling fluid, the acoustic sensors generate signals that are representative of acoustic characteristics if the drilling fluid. Based on the generated signals, a data acquisition system can determine whether a change in the monitored acoustic characteristic is indicative of a gas influx.

Abstract: An acoustic modem for communication in a network of acoustic modems via a communication channel. The acoustic modem comprises a transceiver assembly, transceiver electronics, and a power supply. The transceiver assembly is adapted to convert acoustic messages into electrical signals. The transceiver electronics is provided with transmitter electronics and receiver electronics. The transmitter electronics cause the transceiver assembly to send acoustic signals into the communication channel.

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: A bi-directional acoustic telemetry system is presented for communicating data and/or control signals between a first modem and a second modem along tubing. The system includes a communication channel defined by the tubing, a transducer of the first modem, and a transducer of the second modem. The transducer of each modem are configured to transmit and receive data and/or control signals, and are further configured to electrically communicate with a power amplifier characterized by an output impedance Zs and a signal conditioning amplifier characterized by an input impedance Zr. The system also includes a reciprocal response along the communication channel between the output impedance Zs and the input impedance Zr.

Abstract: An acoustic transceiver assembly including a housing, an oscillator, and at least one membrane. The housing has at least one inner wall defining a cavity. The housing also has a first end and a second end defining an axis of the acoustic transceiver assembly. The oscillator is provided in the cavity. The oscillator is provided with a transducer element, and a backing mass acoustically coupled to the transducer element. The at least one membrane extends outward from the backing mass to support at least the backing mass within the cavity. The at least one membrane is flexible in an axial direction parallel to the axis of the acoustic transceiver assembly to permit the backing mass to oscillate in the axial direction, and rigid in a transverse direction to restrict lateral movement of the backing mass relative to the housing.

Abstract: A method for estimating an impedance of a material behind a casing wall in a borehole, the method comprises exciting the casing wall with an acoustic pulse, and measuring by means of a transducer an experimental acoustic waveform (W) reflected from the casing wall. The method further comprises initializing an impedance parameter (Zin), computing an inverse casing response (Rcas?1) as a function of the impedance parameter (Zin) and a casing thickness parameter (Casin), and deconvoluting the experimental acoustic waveform with the inverse casing response to obtain a transducer response (T). An iterative loop is performed, comprising the computing of an inverse casing response and the deconvoluting of the experimental acoustic waveform by varying the impedance parameter until the transducer response becomes compact in the time domain. The estimated impedance (Zcem) is obtained from the impedance parameter when the transducer response is compact.