Abstract: Measurements made with an induction logging tool are processed to provide a resistivity model of fluid invasion of the formation. Up to five zones can be determined over a radial distance of about 0.6 m. 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.

Abstract: Measurements of acoustic velocities are made through a case borehole in the absence and presence of an applied magnetic field. A formation resistivity parameter may be estimated from differences in the acoustic velocities.

Abstract: Measurements made with an induction logging tool are responsive to formation conductivity and permittivity. The effect of permittivity can be substantially removed by multifrequency focusing.

Abstract: Measurements made by a multi-component logging tool in a borehole are inverted to obtain three principal resistivities (or conductivities) and three associated angles of a bi-axially symmetric formation traversed by the borehole.

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 a direction of a conductivity tensor are determined. The results are used for reservoir navigation in earth formations. 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.

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: 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: 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 misalignment angle between the transmitter and receiver antenna of a multicomponent induction logging tool are estimated from quadrature component signals at multiple frequencies. A transmitter antenna having a first axial direction on a logging tool is excited at a plurality of frequencies. Signals responsive to the excitation are received at a receiver antenna having a second axial direction. A direct field between the transmitter antenna and the receiver antenna is obtained by performing multi-frequency focusing of the received signals. The misalignment angle is estimated from the direct field.

Abstract: A mixed mode tool uses an inductive source and detects galvanic currents and/or potentials at electrodes in proximity to a borehole wall to produce a resistivity image of the earth formation.

Abstract: A mixed mode tool uses an inductive source and detects galvanic currents and/or potentials at electrodes in proximity to a borehole wall to produce a resistivity image of the earth formation. Alternative, the magnetic field produced by a galvanic current is detected by an antenna coil and used to produce a resistivity image. 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 understand that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: Measurements are made with a multicomponent logging tool in an earth formation. The measurements are inverted without using a selected cross-component measurement. The model is then used to predict the value of the selected cross-component. A misalignment angle of the tool is estimated from the predicted and actual values of the selected cross-component.

Abstract: Measurements are made with a multicomponent logging tool in an earth formation. The measurements are inverted without using a selected cross-component measurement. The model is then used to predict the value of the selected cross-component. A misalignment angle of the tool is estimated from the predicted and actual values of the selected cross-component.

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: Measurements are made with a multicomponent logging tool in an earth formation. The measurements are inverted without using a selected cross-component measurement. The model is then used to predict the value of the selected cross-component. A misalignment angle of the tool is estimated from the predicted and actual values of the selected cross-component.

Abstract: A misalignment angle between the transmitter and receiver antenna of a multicomponent induction logging tool are estimated from quadrature component signals at multiple frequencies.

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: 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 a direction of a conductivity tensor are determined. The results are used for reservoir navigation in earth formations. 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.

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 earth formation are determined. The results are used for reservoir navigation in an earth formation. 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.

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.