Abstract: An apparatus and method for a property ahead of a drill bit in a borehole penetrating a formation. The apparatus may include at least one receiver toroid disposed on a carrier and a transmitter toroid configured to induce an electromagnetic signal in the formation and disposed between the drill bit and the at least one receiver toroid. The apparatus may include at least one processor configured to estimate the property using a signal produced by the at least one receiver. The method may include estimating the property using the signal produced by the at least one receiver toroid. The method may also include one or more of: (i) generating a conductivity curve based on signals from at least one receiver toroid, (ii) validating signals from one receiver toroid based on a conductivity curve of another receiver toroid, and (iii) filtering a receiver toroid signal using lateral resistivity information.

Abstract: A system for measuring electric characteristics of an earth formation includes a carrier configured to be disposed in an earth formation, and an inductive measurement assembly including an antenna configured to generate an oscillating magnetic field in the earth formation and measure a resistivity of the formation by detecting a signal in response to currents induced in the formation. The system also includes a capacitive measurement assembly including a capacitive measurement electrode configured to detect a signal in response to a measurement current injected into the formation, the capacitive measurement electrode disposed between the antenna and the formation and in a path of the magnetic field, the capacitive measurement electrode formed from a plurality of constituent electrodes that are electrically isolated from each other so as to prevent induction of eddy currents across the plurality of electrodes.

Abstract: A system for measuring electric characteristics of an earth formation includes a carrier configured to be disposed in an earth formation, and an inductive measurement assembly including an antenna configured to generate an oscillating magnetic field in the earth formation and measure a resistivity of the formation by detecting a signal in response to currents induced in the formation. The system also includes a capacitive measurement assembly including a capacitive measurement electrode configured to detect a signal in response to a measurement current injected into the formation, the capacitive measurement electrode disposed between the antenna and the formation and in a path of the magnetic field, the capacitive measurement electrode formed from a plurality of constituent electrodes that are electrically isolated from each other so as to prevent induction of eddy currents across the plurality of electrodes.

Abstract: An apparatus and method for estimating a parameter of interest in a borehole penetrating an earth formation using a receiver and a transmitter, both disposed on a carrier, with aligned magnetic moments to correct for bending of carrier during borehole investigations. The apparatus may include a transmitter with at least two substantially perpendicular coils and a receiver with at least one coil oriented with at least one or the transmitter coils. The method may include aligning the magnetic moment of the transmitter and the magnetic moment of the receiver prior to estimating the parameter of interest. The method may include supplying a constant electric current to one of the transmitter coils while supplying a varying electric current to another of the transmitter coils. The method may include estimating a direction of bending or angle of bending of the carrier.

Abstract: Disclosed is a method of estimating a property of an earth formation penetrated by a borehole. The method includes conveying a carrier through the borehole and performing a plurality of electrical measurements on the formation using a sensor disposed at the carrier and having a plurality of electrodes disposed in a concentric arrangement wherein a standoff distance between the sensor and a wall of the borehole has an influence on each electrical measurement in the plurality of electrical measurements. The method further includes determining an impedance for each electrical measurement in the plurality of electrical measurements and inputting the determined impedances into an artificial neural network implemented by a processor. The artificial neural network outputs the property wherein the outputted property compensates for the influence of sensor standoff distance on each electrical measurement in the plurality of electrical measurements.

Abstract: An apparatus and method for a property ahead of a drill bit in a borehole penetrating a formation. The apparatus may include at least one receiver toroid disposed on a carrier and a transmitter toroid configured to induce an electromagnetic signal in the formation and disposed between the drill bit and the at least one receiver toroid. The apparatus may include at least one processor configured to estimate the property using a signal produced by the at least one receiver. The method may include estimating the property using the signal produced by the at least one receiver toroid. The method may also include one or more of: (i) generating a conductivity curve based on signals from at least one receiver toroid, (ii) validating signals from one receiver toroid based on a conductivity curve of another receiver toroid, and (iii) filtering a receiver toroid signal using lateral resistivity information.

Abstract: An apparatus and method for estimating a parameter of interest in a borehole penetrating an earth formation using a receiver and a transmitter, both disposed on a carrier, with aligned magnetic moments to correct for bending of carrier during borehole investigations. The apparatus may include a transmitter with at least two substantially perpendicular coils and a receiver with at least one coil oriented with at least one or the transmitter coils. The method may include aligning the magnetic moment of the transmitter and the magnetic moment of the receiver prior to estimating the parameter of interest. The method may include supplying a constant electric current to one of the transmitter coils while supplying a varying electric current to another of the transmitter coils. The method may include estimating a direction of bending or angle of bending of the carrier.

Abstract: A system for measuring a resistivity parameter of an earth formation includes: at least one measurement electrode electrically connected to a first electrical source; at least one guard electrode; a shielding electrode interposed between the at least one guard electrode and the at least one measurement electrode, the shielding electrode being electrically connected to a second electrical source independent from the first electrical source, and the guard electrode being electrically connected to a third electrical source independent of the first and second electrical sources; at least one return electrode; insulators positioned between (i) the measurement electrode and the shielding electrode, (ii) the shielding electrode and the guard electrode and (iii) the measurement electrode, the guard electrode and the return electrode; and a processor configured to adjust at least one of the first electrical source and the second electrical source to minimize a current flow through the shielding electrode.

Abstract: An apparatus for evaluating an earth formation, the apparatus including: a logging tool configured to be conveyed through a borehole penetrating the earth formation; a coil inductively coupled to the earth formation, the coil being disposed at the logging instrument; and a circuit coupled to the coil wherein the circuit and the coil form an oscillator circuit, the oscillator circuit being configured to oscillate when a circuit parameter of the oscillator circuit satisfies an oscillation criterion, the circuit parameter being related to a property of the earth formation.

Abstract: Disclosed is a method of estimating a property of an earth formation penetrated by a borehole. The method includes conveying a carrier through the borehole and performing a plurality of electrical measurements on the formation using a sensor disposed at the carrier and having a plurality of electrodes disposed in a concentric arrangement wherein a standoff distance between the sensor and a wall of the borehole has an influence on each electrical measurement in the plurality of electrical measurements. The method further includes determining an impedance for each electrical measurement in the plurality of electrical measurements and inputting the determined impedances into an artificial neural network implemented by a processor. The artificial neural network outputs the property wherein the outputted property compensates for the influence of sensor standoff distance on each electrical measurement in the plurality of electrical measurements.

Abstract: A method of estimating a property of an earth formation penetrated by a borehole includes: disposing into the borehole a sensor having a plurality of return electrodes and at least one transmitter electrode disposed in a concentric arrangement; injecting a first current of a first frequency into the formation by applying an alternating current voltage between first selected ones of the plurality of return electrodes and the at least one transmitter electrode; injecting a second current of a second frequency into the formation by applying an alternating current voltage between second selected ones of the plurality of return electrodes and the at least one transmitter electrode; measuring effective impedance for each of the currents; and estimating the property using the measurements of the effective impedance for each of the currents; wherein the estimating compensates for an influence of standoff distances of the sensor on the measurements.

Abstract: A method and apparatus for determining a parameter of interest of an earth formation during drilling of a borehole. A first toroidal coil antenna induces a current along a path that includes a bottomhole assembly and the formation. A second toroidal coil antenna disposed at the drillbit and oriented at a non-zero angle to the longitudinal axis of the bottomhole assembly measures an electrical signal resulting from the current, the electrical signal being a parameter of interest of the formations.

Abstract: Disclosed is a method of estimating a property of an earth formation penetrated by a borehole.

Abstract: A method of estimating standoff in a borehole through an earth formation, includes: disposing a sensor including a plurality of return electrodes and at least one transmitter electrode disposed in a concentric arrangement into the borehole; injecting current, I, into the formation by applying at least two frequencies of alternating current (AC) voltage between at least two of the electrodes; measuring impedance, Z, for each of the frequencies; and using a predetermined relationship between impedance, Z, and standoff, estimating the standoff. A system and a computer program product are provided.

Abstract: An apparatus for evaluating an earth formation, the apparatus including: a logging tool configured to be conveyed through a borehole penetrating the earth formation; a coil inductively coupled to the earth formation, the coil being disposed at the logging instrument; and a circuit coupled to the coil wherein the circuit and the coil form an oscillator circuit, the oscillator circuit being configured to oscillate when a circuit parameter of the oscillator circuit satisfies an oscillation criterion, the circuit parameter being related to a property of the earth formation.

Abstract: A method of estimating standoff in a borehole through an earth formation, includes: disposing a sensor including a plurality of return electrodes and at least one transmitter electrode disposed in a concentric arrangement into the borehole; injecting current, I, into the formation by applying at least two frequencies of alternating current (AC) voltage between at least two of the electrodes; measuring impedance, Z, for each of the frequencies; and using a predetermined relationship between impedance, Z, and standoff, estimating the standoff. A system and a computer program product are provided.

Abstract: A system for measuring a resistivity parameter of an earth formation includes: at least one measurement electrode electrically connected to a first electrical source; at least one guard electrode; a shielding electrode interposed between the at least one guard electrode and the at least one measurement electrode, the shielding electrode being electrically connected to a second electrical source independent from the first electrical source, and the guard electrode being electrically connected to a third electrical source independent of the first and second electrical sources; at least one return electrode; insulators positioned between (i) the measurement electrode and the shielding electrode, (ii) the shielding electrode and the guard electrode and (iii) the measurement electrode, the guard electrode and the return electrode; and a processor configured to adjust at least one of the first electrical source and the second electrical source to minimize a current flow through the shielding electrode.

Abstract: A resistivity sub including a resistivity sensor forms part of a bottom hole drilling assembly. The sensor is maintained at a substantially fixed offset from the wall of a borehole during drilling operations by, for example, a stabilizer. In WBM, galvanic sensors may be used, with or without commonly used focusing methods, for obtaining a resistivity image of the borehole wall. In OBM, capacitive coupling may be used. The apparatus is capable of using other types of sensors, such as induction, MPR, shielded dipole, quadrupole, and GPR sensors. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: A method and apparatus for obtaining a resistivity measurement of an earth formation surrounding a borehole in an MWD device uses the drillbit and the adjacent portion of the drill collar as a focusing electrode for focusing the measure current from a measure electrode on the face or side of the drillbit. This provides the ability to see ahead of and azimuthally around the drillbit.

Abstract: A method and apparatus for determining a parameter of interest of an earth formation during drilling of a borehole. A first toroidal coil antenna induces a current along a path that includes a bottomhole assembly and the formation. A second toroidal coil antenna disposed at the drillbit and oriented at a non-zero angle to the longitudinal axis of the bottomhole assembly measures an electrical signal resulting from the current, the electrical signal being a parameter of interest of the formations.