Abstract: A multicomponent induction logging tool includes a transmitter antenna and two receiver antennas, one of which is aligned parallel to the transmitter. Using measurements made at a plurality of rotational angles, a misalignment angle between the transmitter antenna and the second receiver antenna is estimated.

Abstract: Neural networks may be used to determine and predict formation dip angles and perform quality assurance assessments from data collected with a multi-component induction tool used for well logging. The neural networks make use of corrected, rotated and normalized data to provide the predictions and assessments. Synthetic data using various models is used to train the neural networks. The teachings herein provide for real-time determinations with a substantial degree of accuracy in the results.

Abstract: A measurement-while-drilling or logging while drilling method and apparatus for determining the azimuth of providing magnetic field in a remote formation layer in the vicinity of a down hole resistivity tool. A cross-component magnetic field with substantially orthogonal transmitter and receiver coils is provided. The coil planes are either substantially orthogonal (coaxial coils) or parallel (transverse coils) with respect to, the longitudinal axis of the tool body. The coils are placed on the tool body having a external surface and a plurality of grooves are cut in the external surface of the tool body and oriented substantially horizontally with respect to the longitudinal axis of the tool body for the coils and oriented vertically with respect to the longitudinal axis of the tool body for the coaxial coils. A transverse and coaxial coil are placed in the grooves for transmission or reception of a cross-component transverse magnetic field.

Abstract: An induction logging tool having transmitter and receiver antennas is used to make measurements of earth formations. The antennas may be mounted on the mandrel of a bottomhole assembly for MWD applications, or may be pad mounted for wireline applications. The induction measurements are inverted using a linearized model. The model parameters are determined in part from caliper measurements.

Abstract: A resistivity tool has a body with at lest one pair of grooves on its exterior oriented orthogonal to the tool axis. A coil antenna is oriented orthogonal to the grooves in a hole intersecting the grooves and oriented orthogonal to the tool axis. The antenna and an antenna core define a plurality of small antenna loops.

Abstract: An induction logging tool having concentric transmitter and receiver antennas can be used to make measurements of earth formations at frequencies up to 500 MHz. The antennas may be mounted on the mandrel of a bottomhole assembly for MWD applications, or may be pad mounted for wireline applications. Litz winding is used in the coils to minimize eddy current losses. The antennas may be formed on a flexible circuit board.

Abstract: An induction logging tool is used on a MWD bottom hole assembly. Due to the finite, nonzero, conductivity of the mandrel, conventional multi frequency focusing (MFF) does not work. A correction is made to the induction logging data to give measurements simulating a perfectly conducting mandrel. MFF can then be applied to the corrected data to give formation resistivities.

Abstract: A method is discussed of obtaining a parameter of interest of an earth formation, typically a formation resistivity or a distance to a bed boundary, in conditions where an induction tool is using having a body with finite, non-zero conductivity. The method substantially removes the effects of the conductivity of the tool from the signal received from the earth formation. A Taylor series expansion in one half of odd integer powers of time is used to represent the received signal. At least one leading term of the Taylor series expansion can be subtracted from the second signal. A filtering operation is applied to the second signal to remove the terms most dominated by pipe effects. Typical filtering operations can be a differential filtering operation or an integral filtering operation.

Abstract: A multicomponent induction logging tool is used on a MWD bottomhole assembly. Multifrequency focusing that accounts for the finite, nonzero, conductivity of the mandrel is applied. Using separation of modes, the principal components and relative dip angles in an anisotropic medium are determined. The results are used for reservoir navigation in anisotropic media.

Abstract: Multifrequency focusing is applied to measurements made with a multicomponent resistivity logging tool in an earth formation having resisitivity anisotropy. From knowledge of relative dip and azimuth of the borehole relative to the formation, two modes can be separated, one of which is dependent substantially on the horizontal resistivity. Alternatively, mode separation and angle determination can be made simultaneously.

Abstract: A multicomponent induction logging tool is used on a MWD bottomhole assembly. Multifrequency focusing that accounts for the finite, nonzero, conductivity of the mandrel is applied. Using separation of modes, the principal components and relative dip angles in an anisotropic medium are determined. The results are used for reservoir navigation in anisotropic media.

Abstract: An induction logging tool is used on a MWD bottom hole assembly. Due to the finite, nonzero, conductivity of the mandrel, conventional multi frequency focusing (MFF) does not work. A correction is made to the induction logging data to give measurements simulating a perfectly conducting mandrel. MFF can then be applied to the corrected data to give formation resistivities.

Abstract: A method is discussed of obtaining a parameter of interest of an earth formation, typically a formation resistivity or a distance to a bed boundary, in conditions where an induction tool is using having a body with finite, non-zero conductivity. The method substantially removes the effects of the conductivity of the tool from the signal received from the earth formation. A Taylor series expansion in one half of odd integer powers of time is used to represent the received signal. At least one leading term of the Taylor series expansion can be subtracted from the second signal. A filtering operation is applied to the second signal to remove the terms most dominated by pipe effects. Typical filtering operations can be a differential filtering operation or an integral filtering operation.

Abstract: An induction logging tool is used on a MWD bottom hole assembly. Due to the finite, nonzero, conductivity of the mandrel, conventional multi frequency focusing (MFF) does not work. A correction is made to the induction logging data to give measurements simulating a perfectly conducting mandrel. MFF can then be applied to the corrected data to give formation resistivities.

Abstract: A measurement-while-drilling or logging while drilling method and apparatus for determining the azimuth of providing magnetic field in a remote formation layer in the vicinity of a down hole resistivity tool. A cross-component magnetic field with substantially orthogonal transmitter and receiver coils is provided. The coil planes are either substantially orthogonal (coaxial coils) or parallel (transverse coils) with respect to, the longitudinal axis of the tool body. The coils are placed on the tool body having a external surface and a plurality of grooves are cut in the external surface of the tool body and oriented substantially horizontally with respect to the longitudinal axis of the tool body for the coils and oriented vertically with respect to the longitudinal axis of the tool body for the coaxial coils. A transverse and coaxial coil are placed in the grooves for transmission or reception of a cross-component transverse magnetic field.

Abstract: An induction logging tool is used on a MWD bottom hole assembly. Due to the finite, nonzero, conductivity of the mandrel, conventional multi frequency focusing (MFF) does not work. A correction is made to the induction logging data to give measurements simulating a perfectly conducting mandrel. MFF can then be applied to the corrected data to give formation resistivities.

Abstract: Measurements are made with a multicomponent induction logging tool in earth formations in a borehole inclined to earth formations. A combination of principal component measurements is used to determine the horizontal resistivity of the earth formations. The determined horizontal resistivities are used in a model for inversion of other components of the data to obtain the vertical formations resistivities. When multifrequency measurements are available, frequency focusing is used.

Abstract: Skin-effect corrections are applied to measurements made by a transverse induction logging tool to give corrected measurements indicative of vertical conductivities of a formation. Data from a conventional induction logging tool are inverted or focused to give an isotropic model of formation resistivity. A forward modeling is used to derive from the isotropic model measurements that would be expected with a transverse induction logging tool. Skin-effect corrections are applied to these expected measurements. The formation anisotropy is determined from the skin-effect corrected transverse induction measurements, the skin-effect corrected expected measurements and from the isotropic model conductivities.

Abstract: Measurements are made with a multicomponent induction logging tool in earth formations in a borehole inclined to earth formations. A combination of principal component measurements is used to determine the horizontal resistivity of the earth formations. The determined horizontal resistivities are used in a model for inversion of other components of the data to obtain the vertical formations resistivities. When multifrequency measurements are available, frequency focusing is used.

Abstract: Skin-effect corrections are applied to measurements made by a transverse induction logging tool to give corrected measurements indicative of vertical conductivities of a formation. Data from a conventional induction logging tool are inverted or focused to give an isotropic model of formation resistivity. A forward modeling is used to derive from the isotropic model measurements that would be expected with a transverse induction logging tool. Skin-effect corrections are applied to these expected measurements. The formation anisotropy is determined from the skin-effect corrected transverse induction measurements, the skin-effect corrected expected measurements and from the isotropic model conductivities.