Abstract: An embodiment of a method of predicting drilling assembly performance includes: acquiring measurements of electromagnetic (EM) radiation emitted due to destruction of formation materials by a drilling assembly during a drilling operation; selecting input parameters, the input parameters including drilling assembly parameters, operational parameters, and the measurements of the EM radiation; supplying the input parameters to a mathematical drillability model; and generating a rock drillability parameter using the drillability model and the input parameters, the rock drillability parameter providing an indication of drilling performance.

Abstract: An embodiment of a method of predicting drilling assembly performance includes: acquiring measurements of electromagnetic (EM) radiation emitted due to destruction of formation materials by a drilling assembly during a drilling operation; selecting input parameters, the input parameters including drilling assembly parameters, operational parameters, and the measurements of the EM radiation; supplying the input parameters to a mathematical drillability model; and generating a rock drillability parameter using the drillability model and the input parameters, the rock drillability parameter providing an indication of drilling performance.

Abstract: Disclosed is a method implemented by a processor for imaging a formation penetrated by a borehole. The method includes: obtaining acoustic data in a depth-time domain using an acoustic downhole tool disposed at a depth in the borehole, the acoustic downhole tool having an acoustic source and an acoustic receiver; transforming the acoustic data in the depth-time domain into a Radon domain using a Radon transform; filtering the acoustic data in the Radon domain to increase a signal of interest in the acoustic data in the Radon domain; determining a location of a point in the formation that reflected acoustic energy emitted from the acoustic source to the acoustic receiver, the location of the point being represented in the Radon domain; and inverting the location of the point represented in the Radon domain into a radius-depth domain to image the formation.

Abstract: A method for determining permeability of a porous medium of a formation, the method including: placing a logging instrument into a borehole that traverses the porous medium, the borehole filled with a borehole fluid; measuring a pressure, p(1), of an acoustic wave in the borehole at about a boundary between the porous medium and the borehole, the acoustic wave comprising a frequency that is about a resonant frequency of a system that includes the borehole and the porous medium; calculating the permeability from the pressure; and providing the permeability as output to a user.

Abstract: An apparatus for detecting a position of a component in an earth formation is disclosed. The apparatus includes: a transmitter configured to emit a first magnetic field into the earth formation and induce an electric current in the component, the transmitter having a first magnetic dipole extending in a first direction; and a receiver for detecting a second magnetic field generated by the component in response to the first magnetic field, the receiver having a second magnetic dipole extending in a second direction orthogonal to the first direction. A method and computer program product for detecting a position of a component in an earth formation is also disclosed. Apparatus and methods are also disclosed for estimating a position of a second borehole being drilled relative to an existing first borehole.

Abstract: A transient electromagnetic (TEM) signal is recorded in an earth formation during vibration of a logging tool. Concurrently, accelerometer measurements are made. The accelerometer measurements are used to correct the TEM signal for the vibration using the accelerometer measurement and a transfer function relating the TEM signal and the accelerometer. The transfer function may be determined using measurements in a water tank or by using the tail end of the TEM measurements.

Abstract: An apparatus and method for providing a downhole acoustic source is disclosed. The acoustic source includes a piston configured to oscillate in an axial direction of the acoustic source and produce an acoustic signal in a medium in contact with an exterior surface of the piston, and an elastomer disposed on an interior side of the piston, an acoustic impedance of the elastomer selected to match an acoustic impedance of the piston. A permanent magnet is configured to provide a permanent magnetic field oriented in the axial direction, and a coil disposed on an interior side of the piston produces an alternating magnetic field in the region of the permanent magnetic field. The elastomer may be, for example, a silicon rubber, a silicone jelly, and a silicone oil. A plurality of acoustic sources may be arranged to produce an acoustic dipole configuration or an acoustic quadrupole configuration.

Abstract: Disclosed is a method implemented by a processor for imaging a formation penetrated by a borehole. The method includes: obtaining acoustic data in a depth-time domain using an acoustic downhole tool disposed at a depth in the borehole, the acoustic downhole tool having an acoustic source and an acoustic receiver; transforming the acoustic data in the depth-time domain into a Radon domain using a Radon transform; filtering the acoustic data in the Radon domain to increase a signal of interest in the acoustic data in the Radon domain; determining a location of a point in the formation that reflected acoustic energy emitted from the acoustic source to the acoustic receiver, the location of the point being represented in the Radon domain; and inverting the location of the point represented in the Radon domain into a radius-depth domain to image the formation.

Abstract: Cross-dipole measurements are obtained in a borehole. By estimating a direction of polarization of the fast shear mode at low and high frequencies and comparing the estimated distances, a cause of anisotropy is established. Formation stresses and directions may be estimated.

Abstract: The method disclosed is useful for estimating anisotropic properties of an earth formation. The method includes extracting travel time values of components of the acoustic wave induced from a downhole tool and reflected from a boundary bed formation. The method further includes obtaining a travel time ratio of the wave components and using the travel time ratio to estimate the anisotropic properties of the formation.

Abstract: A transient electromagnetic (TEM) signal is recorded in an earth formation during vibration of a logging tool. Concurrently, accelerometer measurements are made. The accelerometer measurements are used to correct the TEM signal for the vibration using the accelerometer measurement and a transfer function relating the TEM signal and the accelerometer. The transfer function may be determined using measurements in a water tank or by using the tail end of the TEM measurements.

Abstract: A method and apparatus for assessing the permeability of a subterranean formation and the hydrocarbon and/or water content of the formation. The method includes emitting an acoustic signal, such as a Stoneley wave into the formation and sending an electro-magnetic pulse into the formation. An analysis of the response of the Stoneley wave in conjunction with an analysis of a measurement of the electrical potential within the wellbore provides information pertinent to permeability and fluid composition.

Abstract: An acoustic source on a logging tool is used to generate acoustic waves in a borehole. Acoustic detectors on the logging tool measure the generated acoustic waves. Electrodes on the logging tool are used to measure the potential resulting from the generated acoustic wave. The output of the hydrophones and the electrodes corresponding to Stoneley wave components of the acoustic wave are processed to provide an estimate of formation permeability, acoustoelectric constant, and a velocity of a propagating second compressional wave in the formation.

Abstract: Measurements of impedance are made using a piezoelectric transducer oriented at different angles to a formation bedding plane. The impedance measurements are then used to estimate the anisotropic velocity of the formation.

Abstract: A method and apparatus useful to determine the integrity of a cement bond log disposed in the annular space between a casing and a wellbore. The method and apparatus produce a transversely polarized shear wave and emit the wave through the casing and into the wellbore. The transversely polarized shear wave attenuates upon passage through the cement bond log. The integrity of the cement bond log can be determined through an analysis and evaluation of the attenuation results.

Abstract: An apparatus and method for providing a downhole acoustic source is disclosed. The acoustic source includes a piston configured to oscillate in an axial direction of the acoustic source and produce an acoustic signal in a medium in contact with an exterior surface of the piston, and an elastomer disposed on an interior side of the piston, an acoustic impedance of the elastomer selected to match an acoustic impedance of the piston. A permanent magnet is configured to provide a permanent magnetic field oriented in the axial direction, and a coil disposed on an interior side of the piston produces an alternating magnetic field in the region of the permanent magnetic field. The elastomer may be, for example, a silicon rubber, a silicone jelly, and a silicone oil. A plurality of acoustic sources may be arranged to produce an acoustic dipole configuration or an acoustic quadrupole configuration.

Abstract: A method useful for evaluating the presence and/or the quality of the cement bond of a downhole tubular. The method involves measuring radial resonance modes of the tubular, and comparing those measured values to the unbound tubular resonant values of a calibration ring. For a well bonded tubular, the measured radial resonance should be greater than that of the unbound tubular calibration ring. In regions where a fluid, such as water surrounds the outside of the tubular, or the cement is otherwise not bonded to the outer surface of the tubular, the measured response should be less than the calibrated response. The calibration ring should have the same diameter, wall thickness, and be made of the same material as the tubular.

Abstract: An apparatus for detecting a position of a component in an earth formation is disclosed. The apparatus includes: a transmitter configured to emit a first magnetic field into the earth formation and induce an electric current in the component, the transmitter having a first magnetic dipole extending in a first direction; and a receiver for detecting a second magnetic field generated by the component in response to the first magnetic field, the receiver having a second magnetic dipole extending in a second direction orthogonal to the first direction. A method and computer program product for detecting a position of a component in an earth formation is also disclosed. Apparatus and methods are also disclosed for estimating a position of a second borehole being drilled relative to an existing first borehole.

Abstract: A method and apparatus useful to determine the integrity of a cement bond log disposed in the annular space between a casing and a wellbore. The method and apparatus induce a Lamb wave in the casing and into the wellbore. The Lamb wave attenuates upon passage through the cement bond log. The integrity of the cement bond log can be determined through an analysis and evaluation of the attenuation results.

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.