Abstract: A method for estimating resistivity and dielectric constant values of a multi-layer subterranean formation acquiring electromagnetic propagation measurements of the subterranean formation and processing the measurements via inversion to compute the resistivity and dielectric constant values. A one-dimensional formation model is utilized including a plurality of formation layers in which each of the formation layers includes a resistivity value and a dielectric constant value.

Abstract: An electromagnetic measurement tool for making multi-frequency, full tensor, complex, electromagnetic measurements includes a triaxial transmitter and a triaxial receiver deployed on a tubular member. An electronic module is configured to obtain electromagnetic measurements at four or more distinct frequencies. The measurement tool may be used for various applications including obtaining a resistivity of sand layers in an alternating shale-sand formation; computing a dielectric permittivity, a conductivity anisotropy, and/or a permittivity anisotropy of a formation sample; and/or identifying formation mineralization including discriminating between pyrite and graphite inclusions and/or computing weight percent graphite and/or pyrite in the formation sample.

Abstract: An apparatus for detecting an electromagnetic signal originating in a wellbore includes an antenna comprising a pair of spaced apart electrodes in the ground spaced apart by a first distance having a midpoint at a second distance from the wellbore. The system includes at least one of a shielded electrical cable connecting each electrode to an input of a detector circuit, wherein the shielding is connected to produce common mode noise rejection; b) a second spaced apart electrode pair antenna spaced apart by one half the first distance and having a midpoint spaced ?2/2 times the second distance from the surface of the wellbore, c) a second electrode pair antenna having a common midpoint with and being orthogonal to the at least one electric dipole antenna; and d) wherein the at least one electric dipole antenna is disposed in a second wellbore, the second wellbore having substantially no electrically conductive pipe therein.

Abstract: A formation characterization system can include a processor; memory accessibly by the processor; instructions stored in the memory and executable by the processor to instruct the system to: acquire induction measurements in a borehole in a formation using an induction tool; determine dielectric properties of the formation using the induction measurements; and generate a log that characterizes particles in the formation based on the dielectric properties.

Abstract: An antenna assembly includes a first leg extending radially over a circumference of a tool, a second leg extending axially over a length of the tool, a third leg radially over a portion of a circumference of the tool, and a fourth leg extending axially over a length of the tool.

Abstract: A logging tool having a plurality of spatially separated antennas is provided and used to make propagation-style measurements in a formation. Tensors are formed using the propagation-style measurements and one or more quantities are computed using the tensors. A formation evaluation is performed using the computed quantities. The formation evaluation determines a formation property or parameter such as horizontal resistivity, vertical resistivity, relative dip, azimuthal dip, bed boundary location, or bed thickness. The computed quantities may include compensated phase shift resistivity, compensated attenuation resistivity, symmetrized phase shift resistivity, symmetrized attenuation resistivity, anti-symmetrized phase shift resistivity, and anti-symmetrized attenuation resistivity. The measurements may be corrected for antenna gain errors and an air calibration may be performed.

Abstract: A method to obtain gain-corrected measurements. A measurement tool having one or more arrays is provided, wherein the arrays include two co-located triaxial transmitters and two co-located triaxial receivers. Measurements are obtained using the transmitters and the receivers. Impedance matrices are formed from the obtained measurements and the impedance matrices are combined to provide gain-corrected measurements. The apparatus may alternatively be a while-drilling logging tool having one or more arrays, wherein each array comprises a transmitter, a receiver, and a buck, and wherein the signal received by the receiver is subtracted from the signal received by the buck or vice versa. A slotted shield may be incorporated into either embodiment of the tool. The slots may form one or more island elements. A material is disposed in the slots. The islands and shield body have complementary tapered sides that confine the islands within the shield body.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: A formation characterization system can include a processor; memory accessibly by the processor; instructions stored in the memory and executable by the processor to instruct the system to: acquire induction measurements in a borehole in a formation using an induction tool; determine dielectric properties of the formation using the induction measurements; and generate a log that characterizes particles in the formation based on the dielectric properties.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: An electromagnetic measurement tool for making multi-frequency, full tensor, complex, electromagnetic measurements includes a triaxial transmitter and a triaxial receiver deployed on a tubular member. An electronic module is configured to obtain electromagnetic measurements at four or more distinct frequencies. The measurement tool may be used for various applications including obtaining a resistivity of sand layers in an alternating shale-sand formation; computing a dielectric permittivity, a conductivity anisotropy, and/or a permittivity anisotropy of a formation sample; and/or identifying formation mineralization including discriminating between pyrite and graphite inclusions and/or computing weight percent graphite and/or pyrite in the formation sample.

Abstract: The claimed technical decision relates to downhole systems for the production of various fluids—in particular, for the production of fluid from a hydrocarbon-bearing formation with the use of hydraulic fracturing. According to the claimed technical decision, a method is disclosed for determining the parameters of the hydraulic fracture near wellbore zone, wherein a cased well with a cemented casing and perforation clusters within the predefined hydraulic fracturing zone or an open hole well is provided. Then, electromagnetic logging is performed prior to formation hydraulic fracturing. The stage, during which the fracturing fluid not containing proppant is injected into the well, and the stage, during which the fracturing fluid containing electrically non-conductive proppant is injected into the well, are performed. Following this, the stage is performed, during which the fracturing fluid containing electrically conductive proppant is injected into the well.

Abstract: An apparatus for detecting an electromagnetic signal originating in a wellbore includes an antenna comprising a pair of spaced apart electrodes in the ground spaced apart by a first distance having a midpoint at a second distance from the wellbore. The system includes at least one of a shielded electrical cable connecting each electrode to an input of a detector circuit, wherein the shielding is connected to produce common mode noise rejection; b) a second spaced apart electrode pair antenna spaced apart by one half the first distance and having a midpoint spaced ?2/2 times the second distance from the surface of the wellbore, c) a second electrode pair antenna having a common midpoint with and being orthogonal to the at least one electric dipole antenna; and d) wherein the at least one electric dipole antenna is disposed in a second wellbore, the second wellbore having substantially no electrically conductive pipe therein.

Abstract: A method for obtaining full tensor gain compensated propagation measurements includes processing a full tensor voltage measurement to obtain a fully gain compensated tensor quantity. An electromagnetic logging tool including at least first and second axially spaced transmitters and at least first and second axially spaced receivers is rotated in a subterranean borehole. A plurality of voltage measurements are acquired while rotating to obtain a full tensor voltage measurement which is in turn processed to obtain the fully gain compensated tensor quantity.

Abstract: A method for obtaining full tensor gain compensated propagation measurements includes processing a full tensor voltage measurement to obtain a fully gain compensated tensor quantity. An electromagnetic logging tool including at least first and second axially spaced transmitters and at least first and second axially spaced receivers is rotated in a subterranean borehole. A plurality of voltage measurements are acquired while rotating to obtain a full tensor voltage measurement which is in turn processed to obtain the fully gain compensated tensor quantity.

Abstract: A method for obtaining gain corrected triaxial electromagnetic propagation measurements with an offset correction includes deploying an electromagnetic logging tool in a subterranean borehole. The logging tool includes at least first and second axially spaced triaxial transmitters and at least first and second axially spaced triaxial receivers. A plurality of full tensor voltage measurements may be acquired and processed tensor term by tensor term to obtain a full tensor, gain corrected quantity. The processing may optionally include (i) removing a full tensor voltage offset from the acquired full tensor voltage measurements to obtain a corresponding plurality of offset corrected voltage tensors and (ii) processing the offset corrected voltage tensor term by tensor term to obtain the full tensor, gain and offset corrected quantity.

Abstract: A method for obtaining full tensor gain compensated propagation measurements includes processing a full tensor voltage measurement to obtain a fully gain compensated tensor quantity. An electromagnetic logging tool including at least first and second axially spaced transmitters and at least first and second axially spaced receivers is rotated in a subterranean borehole. A plurality of voltage measurements are acquired while rotating to obtain a full tensor voltage measurement which is in turn processed to obtain the fully gain compensated tensor quantity.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: A method for obtaining full tensor gain compensated propagation measurements includes processing a full tensor voltage measurement to obtain a fully gain compensated tensor quantity. An electromagnetic logging tool including at least first and second axially spaced transmitters and at least first and second axially spaced receivers is rotated in a subterranean borehole. A plurality of voltage measurements are acquired while rotating to obtain a full tensor voltage measurement which is in turn processed to obtain the fully gain compensated tensor quantity.

Abstract: The present disclosure relates to a method to determine a formation property of a subsurface formation. A downhole logging tool having two or more antennas, at least two of the antennas having a transversely-sensitive element and an axially-sensitive element is provided. Azimuthally-sensitive measurements are obtained using the antennas of the downhole logging tool. The measurements are fitted to a Fourier series having Fourier coefficients that include channel gains, if any. A DC component, a first harmonic component, and a second harmonic component are determined from the Fourier series, a measurement type is determined using the DC component, the first harmonic component, and/or the second harmonic component, and the formation property of the subsurface formation is determined using the determined measurement type.