Abstract: A well logging instrument housing includes an electrically non-conductive tube and at least one layer of fiber embedded in a matrix surrounding an exterior of the tube. The at least one fiber layer includes at least one carbon fiber. The at least one or carbon fiber is arranged to have substantially no closed loops.

Abstract: A downhole logging tool includes a tool body having a co-located set of antennas located on the tool body and first and second antennas formed from respective first and second pairs of coil windings having a closed-loop pattern. Both the first and second pair of coil windings are arranged on diametrically opposed antenna sections. A cylindrical shield is disposed over the co-located set of antennas and has a first set of vertical slots arranged interposed between each of the underlying antenna sections, a second set of vertical slots arranged over each of the underlying antenna sections, with each of the second set of vertical slots being perpendicular to a portion of the coil winding in the underlying antenna section, and a set of non-vertical slots arranged over each the underlying antenna sections. Each of non-vertical slots is perpendicular to a portion of the coil winding in the underlying antenna section.

Abstract: Systems, methods, and devices for two-way communication with a downhole tool string are provided. In one example, a method may include placing a downhole tool string into a pressure riser of a well while at least one component of the downhole tool string is not activated. Thereafter, a wireless control signal may be issued through the pressure riser to the downhole tool to cause the downhole tool string to activate the component. The wireless control signal may involve an acoustic signal, an optical signal, and/or an electromagnetic signal such as electrical dipole coupling or magnetic dipole coupling.

Abstract: A downhole logging tool includes a tool body having a co-located set of antennas located on the tool body and first and second antennas formed from respective first and second pairs of coil windings having a closed-loop pattern. Both the first and second pair of coil windings are arranged on diametrically opposed antenna sections. A cylindrical shield is disposed over the co-located set of antennas and has a first set of vertical slots arranged interposed between each of the underlying antenna sections, a second set of vertical slots arranged over each of the underlying antenna sections, with each of the second set of vertical slots being perpendicular to a portion of the coil winding in the underlying antenna section, and a set of non-vertical slots arranged over each the underlying antenna sections. Each of non-vertical slots is perpendicular to a portion of the coil winding in the underlying antenna section.

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: An antenna insulating structure for a well logging instrument includes an antenna bed disposed in a recess formed in an exterior of an instrument mandrel. A feed through port is disposed in the recess and provides a passage between the recess and an atmospheric chamber in the instrument mandrel. An antenna is disposed on the antenna bed and is electrically coupled to the atmospheric chamber through a feedthrough disposed in the port. The port is filled with a sealing material. An antenna cover is disposed on the antenna. At least one of the antenna bed, the sealing material and the antenna cover is made from polyether ether ketone (PEEK) or a composite material thereof.

Abstract: This disclosure relates to a downhole logging tool for acquiring data in an earth formation. In one embodiment, the downhole logging tool has a tool body with a longitudinal axis, a set of antennas located on the tool body and including coil windings forming a closed-loop pattern, and a shield disposed over the antennas and having an arrangement of slots with each slot being substantially perpendicular to a proximate portion of at least one of the underlying coil windings, wherein the path length around each slot is more than twice the length of the distance between the slot and a directly adjacent slot along an arc of the coil windings. The downhole logging tool may be a wireline or while-drilling tool, and it may be an induction or propagation tool.

Abstract: Subsurface formation evaluation comprising, for example, sealing a portion of a wall of a wellbore penetrating the formation, forming a hole through the sealed portion of the wellbore wall, injecting an injection fluid into the formation through the hole, and determining a saturation of the injection fluid in the formation by measuring a property of the formation proximate the hole while maintaining the sealed portion of the wellbore wall.

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: Systems, methods, and devices for two-way communication with a downhole tool string are provided. In one example, a method may include placing a downhole tool string into a pressure riser of a well while at least one component of the downhole tool string is not activated. Thereafter, a wireless control signal may be issued through the pressure riser to the downhole tool to cause the downhole tool string to activate the component. The wireless control signal may involve an acoustic signal, an optical signal, and/or an electromagnetic signal such as electrical dipole coupling or magnetic dipole coupling.

Abstract: Compositions of lost circulation materials are provided that are useful for identifying the location of fluid loss in a wellbore. The compositions include additives which enhance a property of the composition such that they can be detected by an LWD or MWD tool capable of measuring the property when the composition is deployed in a region of loss, and can be distinguished by the LWD or MWD tool from the formation and mud fluid. Methods are also provided for using the composition to detect the location of fluid loss and for controlling the loss of fluid from the wellbore. The methods involve deploying the compositions in loss regions by adding the compositions to drilling mud, and measuring a property of the compositions using an LWD or MWD 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: The present invention relates to a downhole logging tool having on its tool body a set of co-located antennas, one or more additional antennas spaced longitudinally apart from the set of co-located antennas, an electromagnetically transparent shield circumferentially surrounding the set of co-located antennas, and an electromagnetically transparent shield circumferentially surrounding each of the one or more additional antennas. The downhole logging tool may be a wireline or while-drilling tool, and it may be an induction or propagation tool. The shields may have slots that are locally perpendicular to the windings of underlying coil antennas.

Abstract: An LWD tool with a tubular having a longitudinal axis and a set of co-located antennas carried in a recess on the tubular is disclosed. The tool carries a shield having an open slot configuration and circumferentially surrounds the set of co-located antennas, a first end of the shield being mechanically and electrically connected to the tubular. The tool also includes an insulating ring carried on the tubular, at least a portion of the insulating ring being disposed between the tubular and a second end of the shield.

Abstract: A casing string in a wellbore has conductive tubulars and modified conductivity (MC) or non-conductive tubulars joined to one another. A MC/non-conductive tubular may be disposed between two conductive tubulars. If there are at least two MC/non-conductive tubulars and at least three conductive tubulars, two of the MC/non-conductive tubulars may be alternately disposed between three of the conductive tubulars. The MC/non-conductive tubulars may be formed from materials such as stainless steel, fiber-reinforced thermal sets, and thermal plastics. One such thermal plastic is polyetheretherketone (PEEK) and it may be glass-reinforced. The conductive tubulars, if electrically isolated, may be used as electrodes to transmit or receive electromagnetic signals. The casing string may used for borehole to surface applications, surface to borehole applications, borehole to borehole applications, or single well applications. The casing string may also have downhole sensors, uphole sensors, and surface sensors.

Abstract: The present disclosure relates to a downhole logging tool that includes two or more tilted antennas having equal tilt angles mounted in or on the tool body. The downhole logging tool may be, for example, a wireline or while-drilling tool, and it may be an induction or propagation tool. Various symmetrized and anti-symmetrized responses may be computed and used to infer formation properties and drilling parameters.

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.

Abstract: Subsurface formation evaluation comprising, for example, sealing a portion of a wall of a wellbore penetrating the formation, forming a hole through the sealed portion of the wellbore wall, injecting an injection fluid into the formation through the hole, and determining a saturation of the injection fluid in the formation by measuring a property of the formation proximate the hole while maintaining the sealed portion of the wellbore wall.

Abstract: An antenna for an electromagnetic tool having a longitudinal axis and a core. The antenna includes a flexible dielectric substrate flexibly conformed about the core and an electrical conductor disposed on the dielectric substrate. The electrical conductor is disposed on the substrate such that the antenna has a dipole moment having any desired direction relative to the longitudinal axis of the tool.

Abstract: The present invention relates to a downhole logging tool having on its tool body a set of co-located antennas, one or more additional antennas spaced longitudinally apart from the set of co-located antennas, an electromagnetically transparent shield circumferentially surrounding the set of co-located antennas, and an electromagnetically transparent shield circumferentially surrounding each of the one or more additional antennas. The downhole logging tool may be a wireline or while-drilling tool, and it may be an induction or propagation tool. The shields may have slots that are locally perpendicular to the windings of underlying coil antennas.