Abstract: A bond log device comprising a sonde, an acoustic transducer, and an acoustic receiver. The acoustic transducer is comprised of a magnet combined with a coil, where the coil is energizable by an electrical current source. The acoustic transducer can also be comprised of an electromagnetic acoustic device. The acoustic transducer is capable of producing various waveforms, including compressional waves, shear waves, transversely polarized shear waves, Rayleigh waves, Lamb waves, and combinations thereof.

Abstract: Array quadrupole data obtained in a LWD environment are processed to determine the shear velocity of an earth formation taking into account dispersion effects caused by the logging tool. When this processing is done in an azimuthally anisotropic formation, the shear velocity that is obtained is the slow shear velocity. When 4C (cross-dipole) data are also obtained, then both the fast and slow shear velocities of an azimuthally anisotropic formation can be obtained.

Abstract: A plurality of heavy mass irregularities attached to an inner wall of the drill collar attenuate waves traveling through the collar. The plurality of heavy mass irregularities are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings firmly coupled to the outer surface of the collar. Alternatively, the mass irregularities may be rings firmly coupled to the outer collar surface by neck pieces, extending inwardly from the inner circumference of the ring. The mass irregularities may be made of steel or tungsten. In another preferred embodiment, the mass irregularities are asymmetrically coupled to an outer collar wall for providing preferential directional attenuation.

Abstract: An acoustic logging apparatus comprises a drill collar conveyed on a drilling tubular in a borehole within a formation. At least one transmitter is disposed in the drill collar. The transmitter includes at least one magnetostrictive actuator cooperatively coupled by a flexure ring to a piston for converting a magnetostrictive actuator displacement into a related piston displacement for transmitting an acoustic signal in the formation.

Abstract: A well system having a sensor; a controller for converting the sensor output, a signal conducting mass, an actuator for inducing an acoustic wave the signal conducting mass, a reaction mass, an acoustic wave receiver up-hole, and a processor for processing a signal from the acoustic wave receiver and for delivering the processed signal to an output device.

Abstract: The present invention provides a method and apparatus for using an acoustic logging tool conveyed in a borehole in an earth formation for determining a characteristic of the formation. The method comprises using a first acoustic source for generating an acoustic signal in the earth formation at a first frequency. A second acoustic source spaced apart from the first source is used for generating an acoustic signal in the earth formation at a second frequency different from the first frequency. An acoustic receiver is used for receiving a third acoustic signal indicative of said characteristic. The third acoustic signal has a frequency substantially equal to a difference between the first frequency and the second frequency. The third acoustic signal is produced by a nonlinear interaction between the first signal and the second signal in a portion of said earth formation.

Abstract: An apparatus for performing acoustic investigations while drilling a borehole in a subsurface geological formation comprises a longitudinally extending assembly conveyed in the borehole on a drilling tubular. The assembly and the drilling tubular have a drilling fluid flowing through a longitudinally extending passage in the assembly and the drilling tubular. An acoustic transmitter is supported by the assembly. The transmitter generates acoustic signals in the assembly, the borehole and the subsurface formation. An acoustic receiver is spaced apart from the transmitter and receive the acoustic signals. An attenuator is located in the assembly between the acoustic transmitter and the acoustic receiver for attenuating the acoustic signals in the assembly within a predetermined frequency range. The attenuator comprises a tubular element of a composite material having a substantially cylindrical outer surface.

Abstract: An acoustic logging apparatus comprises a drill collar conveyed on a drilling tubular in a borehole within a formation. At least one transmitter is disposed in the drill collar. The transmitter includes at least one magnetostrictive actuator cooperatively coupled by a flexure ring to a piston for converting a magnetostrictive actuator displacement into a related piston displacement for transmitting an acoustic signal in the formation.

Abstract: Array quadrupole data obtained in a LWD environment are processed to determine the shear velocity of an earth formation taking into account dispersion effects caused by the logging tool. When this processing is done in an azimuthally anisotropic formation, the shear velocity that is obtained is the slow shear velocity. When 4C (cross-dipole) data are also obtained, then both the fast and slow shear velocities of an azimuthally anisotropic formation can be obtained.

Abstract: A drilling control system provides, in one aspect, advisory actions for optimal drilling. Such a system or model utilizes downhole dynamics data and surface drilling parameters, to produce drilling models used to provide to a human operator with recommended drilling parameters for optimized performance. In another aspect, the output of the drilling control system is directly linked with rig instrumentation systems so as to provide a closed-loop automated drilling control system that optimizes drilling while taking into account the downhole dynamic behavior and surface parameters. The drilling models can be either static or dynamic. In one embodiment, the simulation of the drilling process uses neural networks to estimate some nonlinear function using the examples of input-output relations produced by the drilling process.

Abstract: Determination of the rate of penetration (ROP) of drilling has usually been based upon surface measurements and may not be an accurate representation of the actual ROP. This can cause problems in Logging While Drilling (LWD). Because of the lack of a high-speed surface-to-downhole communication while drilling, a conventional method of measuring ROP at the surface does not provide a solution to this problem. However, the instantaneous ROP can be derived downhole with a certain degree of accuracy by utilizing an accelerometer placed in (or near) the tool to measure acceleration in the axial direction. When three-component accelerometers are used, the method may be used to determine the true vertical depth of the borehole.

Abstract: The present invention provides a semi-passive two-way borehole communication system and method. The system includes a surface source signal generator for generating an acoustic signal. The acoustic source signal is transmitted downhole, and a downhole controllable reflector reflects a portion of the source signal back toward the surface. The reflector is controlled such that an echo signal is created, which contains information to be carried to the surface. A surface receiver is used to detect the echo signal, and a surface controller is used to decode the echo signal.

Abstract: A plurality of heavy mass irregularities attached to an inner wall of the drill collar attenuate waves traveling through the collar. The plurality of heavy mass irregularities are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings secured to the inner surface of the collar by neck pieces, extending outwardly from the outer circumference of the ring. The mass irregularities may be made of steel or tungsten and are between six and ten in number. The spacing of the irregularities may lie between twelve and fourteen centimeters. A center pipe may be included to isolate the irregularities from the fluid flow associated with the drilling operation. The pipe may be of a soft material such as rubber to reduce transfer of acoustic noise along the drill string. The irregularities may be in an oil based fluid with the pipe fitting closely in the center of the rings.

Abstract: The present invention provides a drilling system that utilizes a neural network for predictive control of drilling operations. A downhole processor controls the operation of the various devices in a bottom hole assembly to effect changes to drilling parameters and drilling direction to autonomously optimize the drilling effectiveness. The neural network iteratively updates a prediction model of the drilling operations and provides recommendations for drilling corrections to a drilling operator.

Abstract: The present invention includes a well system having a sensor; a controller for converting the sensor output, a signal conducting mass, a magnetostrictive actuator for inducing an acoustic wave the signal conducting mass, a reaction mass being greater than the signal conducting mass, an acoustic wave receiver up-hole, and a processor for processing a signal from the acoustic wave receiver and for delivering the processed signal to an output device.

Abstract: A plurality of heavy mass irregularities attached to an inner wall of the drill collar attenuate waves traveling through the collar. The plurality of heavy mass irregularities are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings secured to the inner surface of the collar by neck pieces, extending outwardly from the outer circumference of the ring. The mass irregularities may be made of steel or tungsten and are between six and ten in number. The spacing of the irregularities may lie between twelve and fourteen centimeters. A center pipe may be included to isolate the irregularities from the fluid flow associated with the drilling operation. The pipe may be of a soft material such as rubber to reduce transfer of acoustic noise along the drill string. The irregularities may be in an oil based fluid with the pipe fitting closely in the center of the rings.

Abstract: An acoustic MWD system comprises at least one transmitter array and at least one receiver array spaced axially along an essentially tubular downhole subassembly. Each transmitter and receiver array includes a plurality of elements circumferentially disposed on the outside of the assembly. The downhole subassembly also comprises a processor, data storage, telemetry elements, power supplies and control circuits as well as other types of sensors. In one embodiment of the invention, the transmitters are operated as a quadrupole in orthogonal orientations and signals from two receiver elements processed to attenuate common modes (including body waves through the tool, monopole waves and Stoneley waves). In another embodiment, the transmitters are used as crossed dipoles and signals received by cross-dipole receivers may be used to determine shear wave birefringence in the formation.

Abstract: The present invention provides a system for drilling boreholes having a downhole subassembly which contains an acoustic measurement-while-drilling system. It uses the acoustic velocity through the formations surrounding the borehole and an acoustic transmitter and a set of receivers for determining the bed boundaries surrounding the borehole formation. An acoustic isolator on the tool may be used to attenuate body waves traveling between the transmitter and the receivers. Additional attenuation of the body waves is provided by a threshold filter based upon the absolute maximum of the received signals. Semblance of the data is determined in a slowness/intercept-time domain. Coherence and semblance filtering methods are used to differentiate between reflection signals and noise. The position and orientation of the bed boundary relative to the tool are determined.

Abstract: The present invention provides a semi-passive two-way borehole communication system and method. The system includes a surface source signal generator for generating an acoustic signal. The acoustic source signal is transmitted downhole, and a downhole controllable reflector reflects a portion of the source signal back toward the surface. The reflector is controlled such that an echo signal is created, which contains information to be carried to the surface. A surface receiver is used to detect the echo signal, and a surface controller is used to decode the echo signal.

Abstract: The present invention provides a system for drilling boreholes having a downhole subassembly which contains an acoustic measurement-while-drilling system. It uses the acoustic velocity through the formations surrounding the borehole and an acoustic transmitter and a set of receivers for determining the bed boundaries surrounding the borehole formation. An acoustic isolator on the tool may be used to attenuate body waves traveling between the transmitter and the receivers. Additional attenuation of the body waves is provided by a threshold filter based upon the absolute maximum of the received signals. Semblance of the data is determined in a slowness/intercept-time domain. Coherence and semblance filtering methods are used to differentiate between reflection signals and noise. The position and orientation of the bed boundary relative to the tool are determined.