Abstract: A transmitter on an instrument is used to induce currents in an earth formation when it is turned on or off. A Fourier transform is applied to transient measurements made in the receivers. A multifrequency focusing of the transformed data is used for applications like determination of a distance to an interface in the formation, controlling the drilling direction, determination of formation resistivities and formation strike directions.

Abstract: Systems and methods for downhole communication and measurement utilizing an improved metallic tubular having an elongated body with tubular walls and a central bore adapted to receive a run-in tool. The tubular including slotted stations to provide through-tubular signal transmission and/or reception. Hydraulic isolation between the interior and exterior of the tubular is provided by pressure barrier means at the slotted stations. Sensors and/or sources are mounted on the run-in tool, which is adapted for transmission through a drill string to engage within the tubular in alignment with the slotted stations. A run-in tool configuration includes a modulator for real-time wireless communication with the surface and/or remote downhole tools. A tubular and run-in tool configuration also includes inductive couplers for wireless signal data transfer. A method for measuring a formation characteristic utilizing a run-in tool adapted with an interchangeable end segment for multi-mode downhole transport.

Abstract: An arrangement and an associated method are described in which a boring tool is moved through the ground within a given region along a path in which region a cable is buried. The boring tool and the cable transmit a boring tool locating signal and a cable locating signal, respectively. Intensities of the boring tool locating signal and the cable locating signal are measured along with a pitch orientation of the boring tool. Using the measured intensities and established pitch orientation, a positional relationship is determined to relative scale including at least the boring tool and the cable in the region. The positional relationship is displayed to scale in one view. The positional relationship may be determined and displayed including the forward locate point in scaled relation to the boring tool and the cable. Cable depth determination techniques are described including a two-point ground depth determination method.

Abstract: A method for measuring a resistivity of a subsurface formation that includes transmitting continuously a signal at a first fundamental frequency at full power for a first period of time within a single window of time causing electromagnetic energy to propagate in the subsurface formations, transmitting continuously the signal at a second fundamental frequency at full power for a second period of time within the single window of time causing electromagnetic energy to propagate in the subsurface formations, measuring variations in the electromagnetic energy propagated through the subsurface formations at receivers at the first and the second fundamental frequencies, and determining the resistivity of the subsurface formations using the measurements of the variations in electromagnetic energy at the receivers.

Abstract: A method and system for identifying a location of a magnetic field source. A total magnetic field is measured during a calibration routine prior to a drilling procedure. During the drilling procedure, a magnetic field measurement is obtained. Using a ratio of the measured magnetic field and the calibrated field, a set of possible angles and distances is calculated. After the source is advanced a known distance, a second magnetic field measurement is obtained. A second ratio is calculated and a second set of possible angles and distances is calculated. The relative location of the source is then determined using the first set and second set of values, along with the known distance and a pitch angle of the source.

Abstract: Resistivity measurements are made at a plurality of frequencies. An asymptotic high-frequency limit is determined and the electrical efficiency is estimated as a ratio of the high frequency resistivity limit to the low frequency resistivity. From the electrical efficiency, petrophysical parameters of a rock such as porosity and water saturation can be estimated.

Abstract: Using an electromagnetic logging tool, desired antenna responses are synthesized from a combination of measured antenna responses, as well as antenna arrays particularly suited to provide the measurements. Those arrays may include cross dipole and double cross dipole antennas. Direct and derivative responses are used to synthesize the desired response, and the synthesized desired response is used to determine formation properties.

Abstract: An orientation vector, referred to hereinafter as the “geosteering vector,” is directed to the more conductive formation area within the DOI of the tool and away from the more resistive formation areas. Accordingly, drilling in a direction opposite the geosteering vector leads to more resistive formation. Also, the disclosed geosteering vectors obtained from the real and imaginary components will not align with each other for non-planar formations and therefore the misalignment of the geosteering obtained from real and imaginary components is indicative of a non-planar formation. A superposition method is disclosed which can be used to calculate electromagnetic (EM) couplings in a non-planar geometry formation (as well as in a planar geometry formation) in real time, without requiring two or three dimensional modeling calculations.

Abstract: Various systems and methods determine a distance, magnitude, and azimuthal angle describing the location of an anomaly within a geologic formation. For example, a method involves identifying an electrical characteristic (e.g., resistivity or conductivity) at each of several sensors in a measurement-while-drilling (MWD) tool. Based on the electrical characteristic, information identifying a formation property of the anomaly is generated. The information includes at least one magnitude and at least one distance. Information information identifying an azimuthal angle is also generated based upon the electrical characteristic. The azimuthal angle relates a position of the anomalous formation to a position of a first sensor in the MWD tool.

Abstract: An apparatus, method and computer-readable medium for obtaining a resistivity image of an earth formation. The apparatus includes a downhole assembly configured to be conveyed in a borehole penetrating the earth formation; a plurality of sensor electrodes on the downhole assembly, at least one of the electrodes having a different area than another of the electrodes; and at least one processor configured to: (i) process measurements using each of the sensor electrodes; (ii) process a subset of the measurements substantially unaffected by the different capacitances to produce an image of the borehole wall; and (iii) record the image on a suitable medium.

Abstract: A multicomponent induction logging tool is positioned within an alignment loop and the transmitter is activated at a number of rotation angles of the tool. Misalignment between the transmitter and receiver coils can be determined from the induced signals in the receiver coil.

Abstract: A downhole induction resistivity assembly that comprises a downhole tool string component. The tool string component comprises an induction transmitter. The transmitter is adapted to induce an induction field in the surrounding formation. A first induction receiver is spaced apart from the transmitter and is adapted to measure the induction field. A magnetic field generating mechanism is disposed circumferentially adjacent the transmitter and adapted to guide the transmitter's signal into the formation.

Abstract: A logging tool and method to make subsurface measurements is disclosed, wherein the tool is placed within a borehole penetrating a formation. The tool has a transmitter antenna and a receiver antenna spaced apart along a longitudinal axis of the tool, and at least one of the transmitter or receiver antennas has a dipole moment that is non-coaxial with the longitudinal axis of the tool. The at least one non-coaxial antenna can rotate relative to the other antenna. Energy is transmitted from the transmitter antenna and a signal associated with the transmitted energy is measured at the receiver antenna while the at least one non-coaxial antenna rotates relative to the other antenna.

Abstract: Methods and related systems are described for making an electromagnetic induction survey of a formation surrounding a cased section of a borehole. An electromagnetic transmitter and/or receiver are deployed into the cased section of the borehole. One or more additional devices are used to measure the properties of a conductive casing relating to conductivity, thickness and magnetic permeability. A casing coefficient is then calculated that can then be used for the processing of the deep-sensing induction measurements.

Abstract: A retrievable tool for steering through an earth formation includes a first tool assembly and a tilted antenna attached to the first tool assembly. The tool also includes a second tool assembly attached to the first tool assembly and a tilted antenna attached to the second tool assembly. The first tool assembly attaches to the second tool assembly so that the antennas are tilted in predetermined directions. The tilted antennas are transmitter antennas or receiver antennas. Each tool assembly is a tubular cylinder with a longitudinal axis running the length of the cylinder, wherein the tubular cylinder has two ends, each end including a rotational attachment mechanism. The tool assemblies attach to each other through their rotational attachment mechanisms. The rotational attachment mechanism may be a screw-on mechanism, press-fit mechanism, or welded mechanism.

Abstract: An apparatus for detecting movement downhole includes a first downhole component (106) having a sensor (114) coupled thereto and a second downhole component (102) positioned relative to the first downhole component (106). The sensor (114) generates a primary magnetic field that is imposed on the second downhole component (102) thereby generating an induced magnetic field that interacts with the primary magnetic field. Movement of the first downhole component (106) relative to the second downhole component (102) is detected by the sensor (114) by sensing a change in the induced magnetic field.

Abstract: A logging tool includes a tool body; a simple transmitter comprising a single antenna disposed on the tool body; four simple receivers, each comprising a single antenna, disposed on the tool body and spaced apart from the simple transmitter to form four arrays; and an electronic module for controlling operation of the four arrays, wherein the simple transmitter is configured to generate a magnetic field having a transverse component, wherein each of the four simple receivers is sensitive to the magnetic field generated by the simple transmitter, and at least one of the four simple receivers is sensitive to the transverse component of the magnetic field generated by the simple transmitter, and wherein the four arrays are configured to provide measurements at least three depths of investigation.

Abstract: A method and a system are provided for allowing determination of a direction and distance from a tool to anomaly in a formation. The apparatus for performing the method includes at least one transmitter and at least one receiver. An embodiment of the method includes transmitting electromagnetic signals from the at least one transmitter through the formation near the wellbore and detecting responses at the at least one receiver induced by the electromagnetic signals. The method may further include determining the direction from the device to the anomaly based on the detected responses. The method may also include calculating at least one of an apparent azimuth angle and an apparent dip angle based on the responses, monitoring the at least one calculated apparent angle over time, and determining the direction to the anomaly after the at least one monitored apparent angle deviates from a zero value.

Abstract: An EMI-Seismic logging tool for use in a subterranean formation penetrated by a well bore, wherein the system makes electromagnetic and seismic measurements simultaneously using an EM receiver array for both measurements. A method of simultaneously making electromagnetic and seismic measurements in a subterranean formation is also provided.

Abstract: Transient measurements made at two spaced apart receivers responsive to separate activation of two transmitters symmetrically disposed about the two receivers. The transmitters and receivers are on an instrument having a conductive body induces currents in the earth formation. The effect of the conductive body is removed by using deconvolving the signal at one receiver using the measured signal at the other receiver. The symmetric transmitter configuration also enables compensation for receiver differences.

Abstract: A casing inspection device with magnets and flux sensors. Measurements of axial motion of the device are used to get better definition of the axial extent of casing defects. A contact device may be used for motion measurement. The output of the contact device may be used to control the acquisition of flux measurements direction.

Abstract: A method for using a tool in a wellbore in a formation to predict an anomaly in the formation ahead of the device, the tool comprising a transmitter for transmitting electromagnetic signals through the formation and a receiver for detecting response signals. the method comprises a) bringing the tool to a first position inside the wellbore; b) energizing the transmitter to propagate a transient electromagnetic signal into the formation; c) detecting a response signal that has propagated through the formation as a result of the transient signal in step (b); d) calculating a derived quantity for the formation as a function of time based on the detected response signal for the formation; e) plotting the derived quantity for the formation against time; f) moving the tool to at least one other position within the wellbore and repeating steps (b) to (e); g) predicting an anomaly in the formation.

Abstract: A plurality of transmitters on a logging tool are activated simultaneously at substantially the same frequency. When the transmitter outputs are phase-modulated using a mutually orthogonal set of modulating functions, it is possible to recover, from the signal at each receiver, a response corresponding to each of the transmitters.

Abstract: Disclosed herein are electromagnetic resistivity logging systems and methods that employ an antenna configuration having at most two transmitter or receiver antenna orientations that rotate relative to the borehole. The measurements made by this reduced-complexity antenna configuration enable the determination of at least seven components of a coupling matrix, which may be determined using a linear system of equations that express the azimuthal dependence of the measurements. For increased reliability, measurement averaging may be performed in azimuthally spaced bins. The coupling matrix components can then be used as the basis for determining logs of various formation parameters, including vertical resistivity and anisotropy.

Abstract: This invention is directed to a downhole method and apparatus for simultaneously determining the horizontal resistivity, vertical resistivity, and relative dip angle for anisotropic earth formations. The present invention accomplishes this objective by using an antenna configuration in which a transmitter antenna and a receiver antenna are oriented in non-parallel planes such that the vertical resistivity and the relative dip angle are decoupled. Preferably, either the transmitter or the receiver is mounted in a conventional orientation in a first plane that is normal to the tool axis, and the other antenna is mounted in a second plane that is not parallel to the first plane. Although this invention is primarily intended for MWD or LWD applications, this invention is also applicable to wireline and possibly other applications.

Abstract: An arrangement and an associated method are described in which a boring tool is moved through the ground within a given region along a path in which region a cable is buried. The boring tool and the cable transmit a boring tool locating signal and a cable locating signal, respectively. Intensities of the boring tool locating signal and the cable locating signal are measured along with a pitch orientation of the boring tool. Using the measured intensities and established pitch orientation, a positional relationship is determined to relative scale including at least the boring tool and the cable in the region. The positional relationship is displayed to scale in one view. The positional relationship may be determined and displayed including the forward locate point in scaled relation to the boring tool and the cable. Cable depth determination techniques are described including a two-point ground depth determination method.

Abstract: In one aspect of the invention, a sensor assembly for incorporation into a downhole tool string comprises at least one sensor adapted to detect changes in magnetic flux proximate a first portion of the downhole tool string. A second portion of the downhole tool string comprises a characteristic that interferes with a magnetic reading of the at least one sensor. At least one magnetic focusing array is disposed on an outer diameter of the tool string, and the at least one magnetic focusing array reduces an effect on the sensor of the interfering characteristic of the second portion.

Abstract: Resistivity measurements are made at a plurality of frequencies. An asymptotic high-frequency limit is determined and the electrical efficiency is estimated as a ratio of the high frequency resistivity limit to the low frequency resistivity. From the electrical efficiency, petrophysical parameters of a rock such as porosity and water saturation can be estimated.

Abstract: A resistivity sub including a resistivity sensor forms part of a bottom hole drilling assembly. The sensor is maintained at a substantially fixed offset from the wall of a borehole during drilling operations by, for example, a stabilizer. In WBM, galvanic sensors may be used, with or without commonly used focusing methods, for obtaining a resistivity image of the borehole wall. In OBM, capacitive coupling may be used. The apparatus is capable of using other types of sensors, such as induction, MPR, shielded dipole, quadrupole, and GPR sensors. 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 1.72(b).

Abstract: Cross-component measurements in combination with standard propagation resistivity measurements are processed to estimate the vertical and horizontal resistivities, relative dip and relative azimuth of an anisotropic earth formation.

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: The present invention is directed to methods and systems for oil field downhole sensing and communication during drilling and/or production, wherein such methods and systems utilize coaxial cable to transmit electromagnetic (EM) energy, continuously or as a pulse, to passive downhole sensors.

Abstract: An apparatus for making azimuthally sensitive resistivity measurements of a subterranean formation is disclosed. The apparatus includes a magnetically permeably ring deployed about an electrically conductive tool body. An AC voltage supply is coupled to the tool body on opposing sides of the magnetically permeable ring, with at least one connecting conductor crossing outside the ring. Exemplary embodiments of this invention may further include one or more current sensing electrodes deployed in and electrically isolated from an outer surface of a blade deployed on the tool body and may be utilized to make azimuthally resolved formation resistivity measurements.

Abstract: A method of imaging a subterranean formation traversed by a wellbore using a tool comprising a transmitter for transmitting electromagnetic signals through the formation and a receiver for detecting response signals. The tool is brought to a first position inside the wellbore, and the transmitter is energized to propagate an electromagnetic signal into the formation. A response signal that has propagated through the formation is detected. A derived quantity for the formation based on the detected response signal for the formation is calculated, and plotted against time. The tool may be moved to at least one other position within the wellbore where the procedure may be repeated to create an image of the formation within the subterranean formation based on the plots.

Abstract: A system for passing an electromagnetic signal through a casing comprises a tool body that can be positioned inside the casing; means for magnetically saturating the casing in the vicinity of the tool; a transmitter for transmitting an electromagnetic signal from the tool antenna to the outside of the casing for reception at one or more sensors equipped with an antenna and electronic circuits located outside the casing; and a detector for detecting an electromagnetic signal at the tool from the sensor located outside the casing.

Abstract: A method for imaging a geologic deposit using data collected from a borehole includes: selecting an instrument for performing electromagnetic (EM) measurements, the instrument including at least one transmitter and at least one orthogonally oriented receiver; obtaining EM measurement data from the borehole with the instrument; transforming the EM measurement data to acoustic data; and estimating at least one of a direction and a distance from the instrument to the deposit from the data. A computer program product and a system are provided.

Abstract: A method and a system are provided for allowing determination of a distance from a tool to anomaly ahead of the tool. The apparatus for performing the method includes at least one transmitter and at least one receiver. An embodiment of the method includes transmitting electromagnetic signals from the at least one transmitter through the formation surrounding the wellbore and detecting voltage responses at the at least one receiver induced by the electromagnetic signals. The method includes calculating apparent conductivity or apparent resistivity based on a voltage response. The conductivity or resistivity is monitored over time, and the distance to the anomaly is determined from the apparent conductivity or apparent resistivity values.

Abstract: A method to determine a parameter of a subsurface formation such as anisotropy and dip comprises making at least two cross dipole measurements and forming an anti-symmetrized combination from the at least two cross dipole measurements.

Abstract: To determine effect on a magnetic field caused by a lining structure in a wellbore, an array may be deployed into the wellbore lined with the lining structure. The array comprises a plurality of sensors including sensor A configured to operate as a transmitter, sensor B configured to operate as either a transmitter or a receiver, and sensor C configured to operate as a receiver. The array measures magnetic fields using sensor B as a receiver and sensor C in response to activation of sensor B as a transmitter and sensor A. A plurality of lining structure correction factors can be calculated based on the measured magnetic fields, based on the reciprocity of the sensors.

Abstract: A combination of a shallow-reading and a deep-reading, azimuthally sensitive, multiple propagation devices is used for providing depth images the earth formation with different depth of investigation. 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 1.72(b).

Abstract: An electromagnetic logging that includes a support; and at least one four-coil array disposed on the support, wherein the at least one four-coil array comprises: a transmitter, a bucking coil, a receiver, and a trim coil. A method for balancing an induction array includes applying an alternating current to a transmitter of the induction array that comprises the transmitter, a bucking coil and a receiver; measuring a mutual coupling between the transmitter and the receiver; and adding an extra bucking coil, if the mutual coupling exceeds a selected criterion.

Abstract: A formation evaluation system for a subterranean formation penetrated by a wellbore. The formation evaluation system is provided with a downhole tool and a sensor. The downhole tool is positionable in the wellbore. The downhole tool has a downhole electromagnetic unit for communication with a surface electromagnetic unit. The sensor determines at least one wellsite parameter from the electromagnetic signal. The downhole tool and the surface electromagnetic unit are adapted to pass electromagnetic signals there between. The electromagnetic signals pass through the subterranean formation whereby the senor determines the at least one wellsite parameter from the electromagnetic signal.

Abstract: A method that involves developing an electromagnetic property model of a near surface area and using this electromagnetic property model and electromagnetic data acquired using one or more electromagnetic transmitters located above the near surface area and one or more electromagnetic receivers located within a wellbore to determine one or more electromagnetic properties of a subsurface area. Also an electromagnetic data acquisition system that includes one or more electromagnetic transmitters capable of being operated on the earth's surface, one or more first electromagnetic receivers capable of being operated within a wellbore and capable of receiving signals from the one or more electromagnetic transmitters, and one or more second electromagnetic receivers capable of being located on the earth's surface near the one or more electromagnetic transmitters and capable of receiving signals from the one or more electromagnetic transmitters. Related embodiments are also described.

Abstract: A loop antenna useful, for example, in investigation of earth formations. Embodiments of the invention provide a loop antenna circuit comprising a loop antenna disposed to generate, in response to an electromagnetic wave, a pick-up signal on an output node. Loop antenna circuit further includes a tuning network coupled to the loop antenna. The tuning network is disposed to provide simultaneous tuning at a plurality of interrogation frequencies. Further embodiments include a preamplifier circuit coupled to the loop antenna. The preamplifier circuit is disposed to receive the pick-up signal on an input node and provide a high impedance load to the loop antenna for a first of the plurality of interrogation frequencies to reduce the secondary radiation from the loop antenna to below a predetermined value at the said first interrogation frequency.

Abstract: A method to determine one or more parameters of a formation traversed by a borehole, at least a portion of the formation having substantially parallel boundaries, the method comprising disposing a tool in the borehole, wherein the tool includes a transmitter having a dipole moment at an angle ?T with respect to a longitudinal axis of the tool and a receiver having a dipole moment at an angle ?R with respect to the longitudinal axis of the tool, the transmitter and receiver comprising a transmitter-receiver pair; transmitting an electromagnetic signal while rotating the tool; receiving the electromagnetic signal to produce a measured signal from the transmitter-receiver pair; and determining the one or more formation parameters for the portion of the formation having substantially parallel boundaries based on the measured signal from the transmitter-receiver pair.

Abstract: A system and method for communicating data between a downhole tool and a surface controller is provided that comprises a rotating drill string extending in a borehole and having a downhole telemetry module disposed proximate a bottom end thereof and transmitting a first signal across a telemetry channel. A surface telemetry module is disposed proximate a top end of the rotating drill string and is adapted to receive the first signal transmitted by the downhole telemetry module across the transmission channel. The surface telemetry module has a radio frequency transmitter disposed therein for transmitting a second signal related to the first signal. A stationary communication module has a radio frequency receiver adapted to receive the second signal.

Abstract: A subsea communication system includes addressable nodes in a wellbore and addressable nodes on a floor, where the nodes in the wellbore and on the floor are able to communicate wirelessly with each other, such as through a formation.

Abstract: Calibration of the arrays of a multicomponent induction logging tool is achieved by positioning the tool horizontally above ground. The upper and lower housings of the tool are connected by a borehole conductivity simulator which as a resistance comparable to that of a borehole. Axial and radial positioning of the transmitter coils is done by monitoring outputs at receiver coils to achieve a minimum.

Abstract: A method for interpreting transient electromagnetic survey data includes imparting an electromagnetic field in the Earth's subsurface by passing electric current through a transmitter antenna. The electric current includes switched direct current at a selected switching frequency. Voltages induced in a receiver corresponding to electromagnetic effects induced in the Earth's subsurface are detected. Frequency domain electromagnetic response of the Earth's subsurface is determined from the detected voltages and transient electromagnetic response of the Earth's subsurface is determined from the detected voltages.

Abstract: A logging radar system and method for measuring propped fractures and down-hole formation conditions in a subterranean formation including: a radar source; an optical source; an optical modulator for modulating an optical signal from the optical source according to a signal from the radar source; a photodiode for converting the modulated optical signal output from the optical modulator to the source radar signal; a transmitter and receiver unit; and a mixer. The transmitter and receiver unit receives the source radar signal from the photodiode, transmits the source radar signal into the formation and receives a reflected radar signal. The mixer mixes the reflected radar signal with the source radar signal to provide an output. This technology can be used to describe all fractures connected to the wellbore and differentiate between the dimensions of the two vertical wings of a propped fracture.