Abstract: A method for calibrating an electromagnetic core analysis tool is disclosed. The method includes disposing a tilted test loop inside of or outside of a tool having more than one antenna. A uniform test pack, a layered test pack, and an effective media test pack are each disposed in the tool. A signal is induced in a receiver antenna in the tool when a second antenna is energized with a known current of a known frequency. The induced signal is measured and a calibration gain and offset is determined. A corrected signal is produced and compared with the determined signal based on a forward model.

Abstract: A method to estimate water saturation in electromagnetic measurements includes making an electromagnetic measurement and performing at least one of (a) creating an analytical forward model of the EM measurement, (b) creating a numerical finite difference forward model of the EM measurement, and (c) performing an inversion. The method also includes removing at least one petrophysically-adverse alteration of EM measurements in the frequency range from 1 Hz to 100 MHz. A petrophysically-adverse alteration is due to the presence of at least one of the following: pyrite, graphitic-precursors, magnetite, and other conductive minerals.

Abstract: An electromagnetic (EM) telemetry system includes an EM transmitter configured to transmit EM signals downhole and multiple sensors each configured to communicate with the EM transmitter and with another of the multiple sensors. Each sensor is placed a distance from another sensor along a length of a wellbore in the EM telemetry system. The EM telemetry system also includes a processor configured to select two or more sensors of the multiple sensors based on a signal to noise ratio (SNR) of an EM signal received from the two or more selected sensors, a depth of the EM transmitter, or both.

Abstract: A method for recovering data from a downhole tool in a wellbore includes measuring an electromagnetic signal using first and second sensors. At least a portion of the electromagnetic signal is transmitted by a downhole tool positioned in a first wellbore. The first and second sensors are each positioned at a different location along a length of a second wellbore. The electromagnetic signal measured by the first and second sensors is decoded to recover a property measured by the downhole tool.

Abstract: A method for determining existence of a fracture in a formation surrounding a wellbore drilled through subsurface rock formations includes calculating vertical resistivity, horizontal resistivity, apparent formation dip, apparent formation azimuth and axial resistivity for a plurality of longitudinal instrument spacings using measurements from a triaxial induction well logging instrument disposed in the formation. A spread in the axial resistivity values is determined and the axial resistivity spread threshold therefrom. Fracture indicator values and fracture orientation values are calculated from transverse components of the triaxial induction measurements. Presence of a fracture is indicated when at least one of the fracture indicator value exceeds a selected threshold, the axial resistivity spread exceeds the spread threshold and when the apparent formation dip exceeds a selected threshold.

Abstract: A technique facilitates the collection of improved gravitational acceleration measurements and enables use of those measurements in analyzing environmental characteristics of a subterranean region. In one embodiment, a downhole tool is constructed with a gravimeter having a quantum source and an associated detector. The quantum source and detector use a velocity of the quantum source for determining gravitational acceleration measurements that can be employed in evaluating subterranean characteristics.

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: A method for determining a level of organic maturity of a shale gas formation includes inverting multifrequency complex conductivity data to estimate a volume fraction of graphite, turbostatic carbon nanostructures, and pyrite. The inversion is validated using estimates of the volume fraction of graphite, turbostatic carbon nanostructures, and pyrite. The volume fraction of graphite and turbostatic carbon nanostructures is correlated to a level of organic maturity log of the shale gas formation. The level of organic maturity log is validated using sulfur content obtained from pyrolysis or vitrinite reflectance. A variation of an electromagnetic response due to the volume fraction of graphite, turbostatic carbon nanostructures, and pyrite is quantified. The electromagnetic response is modified by removing the quantified variation to obtain resistivity and permittivity values.

Abstract: A method for calibrating an electromagnetic core analysis tool is disclosed. The method includes disposing a tilted test loop inside of or outside of a tool having more than one antenna. A uniform test pack, a layered test pack, and an effective media test pack are each disposed in the tool. A signal is induced in a receiver antenna in the tool when a second antenna is energized with a known current of a known frequency. The induced signal is measured and a calibration gain and offset is determined. A corrected signal is produced and compared with the determined signal based on a forward model.

Abstract: A method for determining orientation of an electrically conductive formation proximate an electrically substantially non-conductive formation includes measuring multiaxial electromagnetic induction response within the substantially non-conductive formation using an instrument disposed in a wellbore drilled through the formations. A difference from zero conductivity is determined for each component measurement of the multiaxial electromagnetic induction response. The differences are used to correct the measured response of each component measurement in the electrically conductive response. The corrected component measurements are used to determine the orientation of the conductive formation.

Abstract: A cable includes at least one plastic impregnated fiber layer and at least one conductor in contact with the at least one fiber layer. In some examples, the fiber may be glass fiber, aramid fiber or carbon fiber. In some examples, the plastic may be thermoset plastic, thermoplastic or chemically set resin. In some examples, the conductor may be an electrical conductor or an optical fiber.

Abstract: A method for determining electromagnetic induction properties of subsurface rock formations includes determining an eccentering angle of a well logging instrument disposed in a wellbore. The instrument includes at least one triaxial induction transmitter and at least one triaxial induction receiver. The eccentering angle is determined from symmetric cross component measurement differences. The triaxial induction measurements made from the at least one receiver are rotated to an apparent eccentering angle of zero. At least one electromagnetic induction property is determined from the rotated triaxial induction measurements.

Abstract: A method for determining existence of a fracture in a formation surrounding a wellbore drilled through subsurface rock formations includes calculating vertical resistivity, horizontal resistivity, apparent formation dip, apparent formation azimuth and axial resistivity for a plurality of longitudinal instrument spacings using measurements from a triaxial induction well logging instrument disposed in the formation. A spread in the axial resistivity values is determined and the axial resistivity spread threshold therefrom. Fracture indicator values and fracture orientation values are calculated from transverse components of the triaxial induction measurements. Presence of a fracture is indicated when at least one of the fracture indicator value exceeds a selected threshold, the axial resistivity spread exceeds the spread threshold and when the apparent formation dip exceeds a selected threshold.

Abstract: A method for determining orientation of an electrically conductive formation proximate an electrically substantially non-conductive formation includes measuring multiaxial electromagnetic induction response within the substantially non-conductive formation using an instrument disposed in a wellbore drilled through the formations. A difference from zero conductivity is determined for each component measurement of the multiaxial electromagnetic induction response. The differences are used to correct the measured response of each component measurement in the electrically conductive response. The corrected component measurements are used to determine the orientation of the conductive formation.

Abstract: A wireline tool string used in a wellbore to determine formation properties is disclosed which comprises one or more transmitter tools disposed within the tool string, each transmitter tool having three linearly independent coils; a receiver tool disposed within the tool string, wherein the receiver tool has three linearly independent coils; and a tool string component disposed between the one or mole transmitter tools and the receiver tool; wherein the one or more transmitter tools are selectably spatially separated from the receiver tool along the tool string to provide a desired depth of investigation and measurements made using the one or more transmitter tools and receiver tool are used to determine formation properties.

Abstract: A cable includes at least one plastic impregnated fiber layer and at least one conductor in contact with the at least one fiber layer. In some examples, the fiber may be glass fiber, aramid fiber or carbon fiber. In some examples, the plastic may be thermoset plastic, thermoplastic or chemically set resin. In some examples, the conductor may be an electrical conductor or an optical fiber.

Abstract: A technique facilitates the collection of improved gravitational acceleration measurements and enables use of those measurements in analyzing environmental characteristics of a subterranean region. In one embodiment, a downhole tool is constructed with a gravimeter having a quantum source and an associated detector. The quantum source and detector use a velocity of the quantum source for determining gravitational acceleration measurements that can be employed in evaluating subterranean characteristics.

Abstract: A method for determining electromagnetic induction properties of subsurface rock formations includes determining an eccentering angle of a well logging instrument disposed in a wellbore. The instrument includes at least one triaxial induction transmitter and at least one triaxial induction receiver. The eccentering angle is determined from symmetric cross component measurement differences. The triaxial induction measurements made from the at least one receiver are rotated to an apparent eccentering angle of zero. At least one electromagnetic induction property is determined from the rotated triaxial induction measurements.

Abstract: A wireline tool string used in a wellbore to determine formation properties is disclosed which comprises one or more transmitter tools disposed within the tool string, each transmitter tool having three linearly independent coils; a receiver tool disposed within the tool string, wherein the receiver tool has three linearly independent coils; and a tool string component disposed between the one or mole transmitter tools and the receiver tool; wherein the one or more transmitter tools are selectably spatially separated from the receiver tool along the tool string to provide a desired depth of investigation and measurements made using the one or more transmitter tools and receiver tool are used to determine formation properties

Abstract: An apparatus for measuring fluid resistivity includes a flow line adapted to be in fluid communication with formation fluids, wherein the flow line includes a first section comprising a first conductive area, a second section comprising a second conductive area, and an insulating section disposed between the first section and the second section to prevent direct electrical communication between the first section and the second section; a first toroid and a second toroid surrounding the flow line around the first section and the second section, respectively, wherein the first toroid is configured to induce an electrical current in a fluid in the flow line and the second toroid is configured to measure the electrical current induced in the fluid in the flow line; and an electronic package to control functions of the first toroid and the second toroid.