Abstract: An example apparatus for generating acoustic waves is disclosed. The example apparatus includes a housing, and at least one plate having a moment arm, wherein each plate couples to the housing. The example apparatus for generating acoustic also includes at least one axial driver coupled to each moment arm, wherein each axial driver aligns with a longitudinal axis of the housing.

Abstract: An example method for generating acoustic waves is disclosed. The example method includes activating at least one driver, transmitting force from the at least one driver to at least one moment arm, and transferring force from the at least one moment arm to at least one plate, thereby causing the at least one plate to vibrate and generate acoustic waves.

Abstract: An example apparatus for generating acoustic waves is disclosed. The example apparatus includes a housing, and at least one plate having a moment arm, wherein each plate couples to the housing. The example apparatus for generating acoustic also includes at least one axial driver coupled to each moment arm, wherein each axial driver aligns with a longitudinal axis of the housing.

Abstract: A measurement device is provided that determines fluid properties from vibration frequencies of a sample cavity and a reference cavity. In one embodiment, the measurement device includes a sample flow tube, a reference flow tube, vibration sources and detectors mounted on the tubes, and a measurement module. The sample flow tube receives a flow of sample fluid for characterization. The reference flow tube is filled with a reference fluid having well-characterized properties. The measurement module employs the vibration sources to generate vibrations in both tubes. The measurement module combines the signals from the vibration detectors on the tubes to determine properties of the sample fluid, such as density, viscosity, compressibility, water fraction, and bubble size. The measurement module may further detect certain flow patterns such as slug flow, for example.

Abstract: A method is provided for analyzing suspended particulate and liquid medium in a fluid stream by transmitting acoustic signals into the fluid, detecting scattered acoustic energy, and determining a parameter related to the density and compressibility of the fluid. In one embodiment, the fluid analysis tool comprises two transmitting transducers intermittently emitting acoustic signals, and two receiving transducers being differently azimuthally positioned with respect to the transmitters. The ratio of the amplitude of scattered signals measured by the two receivers as a result of emission from the first and second transmitters are used to calculate the parameter. In another embodiment, a tool comprising one transmitter and at least three receivers with azimuthal angles in both forward and backward scattering regions with respect to the incident wave is disclosed. The scattering signal amplitudes normalized by the amplitude from one of the receivers is used to identify and monitor the system.

Abstract: A measurement device is provided that determines fluid properties from vibration frequencies of a sample cavity and a reference cavity. In one embodiment, the measurement device includes a sample flow tube, a reference flow tube, vibration sources and detectors mounted on the tubes, and a measurement module. The sample flow tube receives a flow of sample fluid for characterization. The reference flow tube is filled with a reference fluid having well-characterized properties. The measurement module employs the vibration sources to generate vibrations in both tubes. The measurement module combines the signals from the vibration detectors on the tubes to determine properties of the sample fluid, such as density, viscosity, compressibility, water fraction, and bubble size. The measurement module may further detect certain flow patterns such as slug flow, for example.

Abstract: A method and apparatus for measuring properties of fluid flowing through a bore, using a signal transmitted substantially perpendicularly to the direction of flow. A preferred embodiment uses a pair of acoustic transducers mounted in the annular body of the fluid conduit. The tool is constructed so as to be able to operate for a period of years in a downhole environment without maintenance or replacement. An transducer is also described that is adapted to fit within the dimensions of an annular body without suffering a reduction in the length of the transducer backing.

Abstract: The invention is a device and related method of finding from at least one receiver the location of a source of a transmitted acoustic signal. Both signal source and signal receiver are downhole. The invention uses either or both the triangulation method and the holographic method to determine signal location.The triangulation technique uses the relationships existing in Pythagorean's theorem to find source location. In contrast, the holographic technique uses a known velocity structure to assign propagation velocities to volume cells surrounding the receiver. By variational calculus, a ray path and start time may be assigned to a hypothetical source location for a particular receiver position. This is repeated for each receiver position. Where the hypothetical source locations and start times match for multiple receiver locations, the likely position of a source has been found.

Abstract: A system is disclosed for transmitting and receiving acoustic data signals in a well containing a drill string. The system includes devices for transmitting acoustic signals through the drill string, drilling mud, and formation, and further includes methods for transmitting and interpreting the acoustic signal so as to maximize accuracy of the transmission. The methods of the present invention include correlating signals transmitted along different paths or paths of different lengths, using frequency shift keying transmission, using shear waves to transmit signals through downhole equipment and using compression waves to transmit signals through the mud. The signals further give information about the frequency dependence of formation speed of sound and formation acoustic attenuation. The method also give information for imaging the locations of reflective boundaries in the material surrounding the borehole.

Abstract: An apparatus for logging a borehole comprises a non-rotating component and a rotating component that is flexibly attached to the non-rotating component and includes a logging head. The rotating component is centralized independently from the non-rotating component such that the rotating component remains centralized as it rotates, regardless of whether the non-rotating component is centralized. The logging head includes at least one signaling device, a hydrostatic pressure balancing system, a sealed, variable-volume fluid reservoir in fluid communication with said transducer, and a motor housed in said logging head for rotating the rotating component. The apparatus can further include a second non-rotating component suspended below the rotating component.

Abstract: A multi-part logging tool that allows measurement of several distinct independent parameters, which are in turn used to solve for secondary parameters that give information about the properties of the cement outside the casing. Secondary parameters affecting the measured signals are: casing thickness, bond of cement to casing, cement acoustic impedance, cement thickness, channel size and channel material. The present invention comprises a rotating tool that supports a plurality of specifically configured transducers that interrogate a region behind casing having a 10 degree azimuthal resolution and a depth of investigation of at least 0.75 inches behind casing. The transducers on the rotating tool include an array of angled beam transducers, a single-housing pitch-catch transducer and a radial, pulse echo transducer.

Abstract: A standoff compensation system is disclosed for use in an acoustic LWD system. An acoustic transducer is provided to measure the standoff distance between the logging tool and the borehole wall. The present invention includes a downhole processor for determining an index value which is used to align received acoustic formation signal measurements based upon the measured standoff distance. The index value can either be calculated by the downhole processor or can be retrieved from a pre-calculated look-up table in ROM. The processor then shifts the received acoustic formation signals based upon the index value assigned to each formation signal. The aligned acoustic formation signals are stacked, so that a single acoustic formation signal can be obtained for each firing period and either stored in downhole memory, used immediately, or transmitted by telemetry to the surface. The firing of the acoustic formation transmitters occurs in a rapid firing mode, followed by a relatively long idle.

Abstract: A LWD tool is disclosed for detecting the existence of and distance to adjacent bed boundaries. A transmitter assembly generates either a short acoustic pulse or a swept frequency signal that is detected by an associated receiver assembly. The received signal(s) are conditioned and converted to high precision digital signals by an A/D converter. The digitized signals are accumulated and transferred to a digital signal processor via a high speed data bus. The digital signal processor also receives a digital signal representing the transmission signal and compares the transmission signal and the received signals together to enable a downhole microprocessor to derive a time lag for the received signals.

Abstract: A transducer and a receiver for use in logging-while-drilling operations, having internal pressure adjustment mechanisms to equalize the pressure between the interior of the transducer or receiver, and the well fluids.