Abstract: A method includes positioning a coil antenna in a first pipe concentrically arranged within a second pipe, the coil antenna having a first terminal, a second terminal, and one or more wires that exhibit a winding density proceeding radially between the first and second terminals according to a given function. The first and second terminals are then excited with an alternating current or voltage, and a signal is measured between the first and second terminals. A characteristic of at least one of the first and second pipes is then calculated based on the signal.

Abstract: A method includes introducing a pipe inspection tool into a first pipe positioned within a wellbore and further positioned within at least a second pipe. The pipe inspection tool includes an electromagnetic sensor having a coil antenna that includes a coil winding extending axially along at least a portion of the electromagnetic sensor. An excitation signal is transmitted between a first terminal and a second terminal of the coil antenna. A first response signal is measured between a third terminal and a fourth terminal of the coil antenna, wherein at least one of the third and fourth terminals is different from the first and second terminals. The first response signal is then processed to determine a characteristic of the first pipe.

Abstract: A method includes introducing a pipe inspection tool into a first pipe positioned within a wellbore and further positioned within at least a second pipe. The pipe inspection tool includes an electromagnetic sensor having a coil antenna that includes a coil winding extending axially along at least a portion of the electromagnetic sensor. An excitation signal is transmitted between a first terminal and a second terminal of the coil antenna. A first response signal is measured between a third terminal and a fourth terminal of the coil antenna, wherein at least one of the third and fourth terminals is different from the first and second terminals. The first response signal is then processed to determine a characteristic of the first pipe.

Abstract: Methods including conveying a pipe inspection tool into a wellbore having at least a first pipe positioned within a second pipe, the pipe inspection tool including an electromagnetic sensor. A first excitation signal is transmitted from a first x-coil of the electromagnetic sensor, and a first response signal derived from the first excitation signal is received at the first x-coil or a second x-coil of the electromagnetic sensor. A second excitation signal is then transmitted from a first y-coil of the electromagnetic sensor, and a second response signal derived from the second excitation signal is received at the first y-coil or a second y-coil of the electromagnetic sensor. The first and second response signals are then compared to determine an azimuthal characteristic of the second pipe.

Abstract: A method includes obtaining a first small defect response at a given frequency of a first small defect on a first wellbore pipe positioned within a wellbore. A Fourier transform of the first small defect response is then calculated, and a first measured response at the given frequency of a first arbitrary metal loss defect in the first wellbore pipe is obtained with a sensor of a pipe inspection tool. A Fourier transform of the first measured response is then calculated, and a magnitude of the first arbitrary metal loss based on the Fourier transform of the first small defect response and the Fourier transform of the first measured response is then estimated.

Abstract: A method includes positioning a coil antenna in a first pipe concentrically arranged within a second pipe, the coil antenna having a first terminal, a second terminal, and one or more wires that exhibit a winding density proceeding radially between the first and second terminals according to a given function. The first and second terminals are then excited with an alternating current or voltage, and a signal is measured between the first and second terminals. A characteristic of at least one of the first and second pipes is then calculated based on the signal.

Abstract: A method includes introducing a pipe inspection tool into a first pipe positioned within a wellbore and further positioned within at least a second pipe. The pipe inspection tool includes an electromagnetic sensor having a coil antenna that includes a coil winding extending axially along at least a portion of the electromagnetic sensor. An excitation signal is transmitted between a first terminal and a second terminal of the coil antenna. A first response signal is measured between a third terminal and a fourth terminal of the coil antenna, wherein at least one of the third and fourth terminals is different from the first and second terminals. The first response signal is then processed to determine a characteristic of the first pipe.

Abstract: Methods including conveying a pipe inspection tool into a wellbore having at least a first pipe positioned within a second pipe, the pipe inspection tool including an electromagnetic sensor. A first excitation signal is transmitted from a first x-coil of the electromagnetic sensor, and a first response signal derived from the first excitation signal is received at the first x-coil or a second x-coil of the electromagnetic sensor. A second excitation signal is then transmitted from a first y-coil of the electromagnetic sensor, and a second response signal derived from the second excitation signal is received at the first y-coil or a second y-coil of the electromagnetic sensor. The first and second response signals are then compared to determine an azimuthal characteristic of the second pipe.

Abstract: A method includes obtaining a first small defect response at a given frequency of a first small defect on a first wellbore pipe positioned within a wellbore. A Fourier transform of the first small defect response is then calculated, and a first measured response at the given frequency of a first arbitrary metal loss defect in the first wellbore pipe is obtained with a sensor of a pipe inspection tool. A Fourier transform of the first measured response is then calculated, and a magnitude of the first arbitrary metal loss based on the Fourier transform of the first small defect response and the Fourier transform of the first measured response is then estimated.

Abstract: A method is disclosed for the determination of the dip angle of anisotropic earth formations surrounding a wellbore. Electromagnetic couplings among a plural of triad transmitters and triad receivers are measured. Each triad transmitter/receiver consists of coil windings in three mutually orthogonal axes. The transmitter coils and receiver coils are oriented such that mutually symmetrical transmitter pairs or mutually symmetrical receiver pairs are equidistant from a centrally located receiver or transmitter, respectively. The measured signals from the created couplings are used to generate initial separate estimates of the dip angle of the formation. The two discrete determination is of dip angle are then averaged to arrive at a more accurate estimate that approaches the true dip angle in the formation.

Abstract: A method is disclosed for the determination of the dip angle of anisotropic earth formations surrounding a wellbore. Electromagnetic couplings among a plural of triad transmitters and triad receivers are measured. Each triad transmitter/receiver consists of coil windings in three mutually orthogonal axes. The transmitter coils and receiver coils are oriented such that mutually symmetrical transmitter pairs or mutually symmetrical receiver pairs are equidistant from a centrally located receiver or transmitter, respectively. The measured signals from the created couplings are used to generate initial separate estimates of the dip angle of the formation. The two discrete determinations of dip angle are then averaged to arrive at a more accurate estimate that to approaches the true dip angle in the formation.