Abstract: A system includes a controlled acoustic source. The system also includes distributed acoustic sensors along a conduit. The distributed acoustic sensors obtain acoustic signal measurements as a function of position along the conduit in response to at least one acoustic signal provided by the controlled acoustic source. The system also includes a processing unit that generates an acoustic activity plot or report based on the acoustic signal measurements. The acoustic activity plot or report is used to identify at least one acoustic impedance boundary anomaly as a function of position along the conduit.

Abstract: A communication system using vector and scalar potential is disclosed. The system uses field-free potentials signaling for many applications where the absence of shielding effects in sea water, plasma or other dense media due to the fact that the absence of (E,B) fields eliminates the possibility of induced charge and current response in the media being transited.

Abstract: A method for calibration of electromagnetic induction measurement systems. The method includes transmitting, by at least one transmitter of an electric induction measurement system, a magnetic field as a primary signal, wherein the transmitting the magnetic field as the primary signal triggers a current in the soil which current generates a secondary signal, and recording, by a receiver of the electric induction measurement system, the secondary signal at each of at least two heights of the receiver relative to a soil to be measured in order to create an input vector that is a combination of soil properties and environmental properties that contain the properties of the electric induction measurement system, that contains a dataset of n conductivity values of n layers, and that creates, as a starting value, an initial value vector. The initial value vector includes assumptions and apparent electrical conductivities for m measurement heights.

Abstract: The present disclosure relates to detecting subterranean formations using electromagnetic depth sounding. A method for detecting formation properties may comprise of disposing a transmitter at a surface, disposing a receiver at the surface, coupling a high frequency wave to a low frequency wave to form an electromagnetic pulse, transmitting the electromagnetic pulse into a formation from the transmitter, receiving a reflected electromagnetic wave from the formation with the receiver, and determining the depth and nature of the formation from the surface. A formation measuring system may comprise a transmitter, wherein the transmitter is configured to couple a high frequency wave to a low frequency wave to form an electromagnetic pulse. The formation measuring system may further comprise at least one receiver, a data acquisition system, and an analysis unit.

Abstract: A software-defined radiometer includes dual RF front end channels. One RF front end channel processes the horizontal polarization signals and the other RF front end channel processes the vertical polarization signals. Each RF front end channel includes a power splitter for splitting the polarization signals into a plurality of identical polarization signals, a filter bank of N-bandpass filters that have the same bandwidth but different center frequencies and a multi-input switch. The bandpass filters filter the horizontal and vertical polarization signals and provide a plurality of filtered horizontal and vertical polarization signals. A control circuit issues a control signal to the multi-input switch so as to route a desired one of the plurality of filtered horizontal and vertical polarization signals to a programmable frequency converter.

Abstract: A method of identifying in situ conditions of a hydrocarbon reservoir is disclosed. The method comprises, obtaining a sample from an area of interest, such as a sediment sample or water column sample near a hydrocarbon seep; analyzing the sample to detect lipid, protein, and/or nucleic acid signatures that are indicative of the Thermotogales order; identifying the relative abundance of the different genera and/or species of the Thermotogales present in the sample to generate a taxonomy signature of the sample; and then using the taxonomy signature to determine conditions, such as temperature, of the hydrocarbon reservoir.

Abstract: In some embodiments, an apparatus and a system, as well as a method and article, may operate to model electromagnetic data to provide modeled electromagnetic data by solving a first set of surface integral equations that include earth model parameters corresponding to an earth model of a geological formation. Additional activity may include publishing at least some of the modeled electromagnetic data in human-readable form, and/or controlling drilling operations in the geological formation based on the earth model when error between the modeled electromagnetic data and measured electromagnetic data is less than a selected threshold. Additional apparatus, systems, and methods are disclosed.

Abstract: Methods and apparatus for performing formation evaluation in a borehole intersecting an earth formation. Methods may include exciting at a first borehole depth at least one critical refraction wave by steering an acoustic beam transmitted by at least one ultrasonic transmitter to an interface in the formation to intercept the interface at a critical angle; receiving an acoustic signal comprising critical refraction wave data at a logging tool in the borehole; and obtaining a wave property measurement from the critical refraction wave data. The interface may be the borehole wall in an open-hole well or behind casing. Methods include using ultrasonic transmitter(s) to generate the plurality of acoustic beams, identifying critical refraction wave data within the response signal corresponding to the at least one critical refraction wave, and obtaining the wave property measurement from the critical refraction wave data.

Abstract: Methods and systems for imaging a magnetic field as vectors (or scalars if desired) in either two or three dimensions without the need for rastering or relative motion between the sensors and the magnetic field being viewed. A secondary function is to image electric current flow as vectors. Example embodiments can be scaled to fit both large and small applications by using discreet devices or manufacturing with MEMS technologies.

Abstract: A communication system using vector and scalar potential is disclosed. The system uses field-free potentials signaling for many applications where the absence of shielding effects in sea water, plasma or other dense media due to the fact that the absence of (E,B) fields eliminates the possibility of induced charge and current response in the media being transited.

Abstract: A method includes introducing a resistivity logging tool including one or more transmitter coils and one or more receiver coils into a wellbore. First and second signals are then transmitted with a first transmitter coil at first and second frequencies, respectively, and a first receiver coil receives first and second response signals based on the first and second signals. A ratio between the first and second response signals is then calculated to obtain a ratio signal, and the ratio signal is processed in an inversion algorithm. One or more formation characteristics of the subterranean formation may then be determined based on the ratio signal as processed by the inversion algorithm.

Abstract: Disclosed are various systems and methods for remote surface sensing using guided surface wave modes on lossy media. One system, among others, comprises a guided surface waveguide probe configured to launch a guided surface wave along a surface of a lossy conducting medium, and a receiver configured to receive backscatter reflected by a remotely located subsurface object illuminated by the guided surface wave. One method, among others, includes launching a guided surface wave along a surface of a lossy conducting medium by exciting a charge terminal of a guided surface waveguide probe, and receiving backscatter reflected by a remotely located subsurface object illuminated by the guided surface wave.

Abstract: Systems and methods are provided for generating a phase compensated numerically controlled signal using a fixed-point algorithm. In one example, a method includes receiving, at a downhole device, parameters including an input frequency and a compensation value. The method further includes converting, based on the parameters, the input frequency to a delta phase value. The method also includes calculating, with the downhole device, an accumulation error for a digital signal. In response to determining that the accumulation error is greater than or equal to the compensation value, the method removes the accumulation error from the digital signal to generate an output signal.

Abstract: An antenna assembly includes a bobbin that provides a cylindrical body that defines an outer radial surface, an inner radial surface, and a central axis. One or more channels are defined on the outer radial surface, and each channel provides a first sidewall, a second sidewall opposite the first sidewall, a floor, and a pocket jointly defined by the first sidewall and the floor. A coil including one or more wires is wrapped about the bobbin and received within the one or more channels.

Abstract: The present invention relates to an apparatus and method for analyzing underground geophysical properties using the principle of a ground-penetrating radar.

Abstract: A method of processing data from an electromagnetic resistivity logging tool which includes a transmitter coil and a receiver coil is disclosed. The electromagnetic resistivity logging tool is placed at a desired location. The transmitter coil and the receiver coil are positioned at a first azimuthal angle. A signal is transmitted from the receiver coil. The receiver coil then receives a signal. The signal at the receiver coil, a tilt angle of the transmitter coil, a tilt angle of the receiver coil and the first azimuthal angle are then used to calculate a first complex voltage representing at least one component of the received signal.

Abstract: Methods of identifying geological materials of interest comprising (i) providing a nanoprobe composition comprising one or more nanoprobes; wherein the nanoprobe includes (a) at least one tag; and (b) at least one signal generator; (ii) introducing the nanoprobes to a geological material; and (iii) detecting the presence of a signal generated by the signal generator on association of the tag with a target. Nanoprobe compositions identify geological materials, systems include such nanoprobe compositions, and methods use such nanoprobe compositions for the evaluation of geological materials.

Abstract: A method and system includes generating a first coded acoustic signal including pulses each having a modulated signal at a central frequency; and a second coded acoustic signal each pulse of which includes a modulated signal a central frequency of which is a fraction d of the central frequency of the modulated signal for the corresponding pulse in the first plurality of pulses. A receiver detects a third signal generated by a non-linear mixing process in the mixing zone and the signal is processed to extract the third signal to obtain an emulated micro-seismic event signal occurring at the mixing zone; and to characterize properties of the medium or creating a 3D image of the properties of the medium, or both, based on the emulated micro-seismic event signal.

Abstract: A method for measuring the resistivity of geologic formations is described. An electromagnetic field may be generated using at least one stationary long-range transmitter. The frequency of the electromagnetic field may be between and/or including the ULF/ELF range. At least one component of the electromagnetic field may be measured by land, marine, submarine, and/or airborne receiver. A conductivity distribution may be determined based on the at least one measured component. The determined conductivity distribution may be correlated with geological formations and/or hydrocarbon deposits.

Abstract: This method for detecting a disturber of magnetic field amplitude comprises: the emitting (62) of several magnetic fields of different frequencies from a same uniaxial magnetic field source, the amplitudes of the magnetic field emitted at two different unspecified frequencies being related to each other by a predetermined ratio, the measurement (64) of the amplitude of these magnetic fields at different frequencies by means of a same sensor, and the reporting (70) of an amplitude disturber if a ratio between two of said measured amplitudes diverges from a predetermined threshold of the predetermined ratio which relates the amplitudes of the magnetic fields emitted at the same frequencies and, if not, the absence of any reporting.

Abstract: Downhole tools and techniques acquire information regarding nearby conductors such as pipes, well casing, and conductive formations. At least some method embodiments provide a current flow along a drill string in a borehole. The current flow disperses into the surrounding formation and causes a secondary current flow in the nearby conductor. The magnetic field from the secondary current flow can be detected using one or more azimuthally-sensitive antennas. Direction and distance estimates may be obtainable from the azimuthally-sensitive measurements, and can be used as the basis for steering the drillstring relative to the distant conductor. Possible techniques for providing current flow in the drillstring include imposing a voltage across an insulated gap or using a toroid around the drillstring to induce the current flow.

Abstract: A method and apparatus is provided for collecting reservoir data. The method includes providing one or more electromagnetic sources for generating an electromagnetic field in a reservoir and providing one or more electromagnetic sensors equipped with capacitive electrodes. The electromagnetic source is located separately from the electromagnetic sensor. The electromagnetic sensor may either be located within a well or at the surface, is capable of measuring the electromagnetic field in three dimensions, and may be isolated from the well fluids. The data collected by the electromagnetic sensors can be used to create a model of the oil reservoir, including the water saturation.

Abstract: A multicomponent induction logging tool uses a nonconducting mandrel. A central conducting member including wires that electrically connect at least one of the antennas to another of the antennas. Electrodes disposed about the transmitter antenna form a conductive path through a borehole fluid to the central conducting member.

Abstract: A locator for locating a concealed conductor comprises a first field detector operable to detect an alternating magnetic field along a first axis parallel to a primary axis of the locator; a second field detector, displaced from the first field detector and operable to detect an alternating magnetic field along a second axis parallel to the primary axis of the locator; and a processor operable to calculate a difference between a field detected by the first detector and a field detected by the second detector, and to calculate an indication of the lateral displacement of the concealed conductor from the primary axis of the locator using the difference.

Abstract: A system transmits a wireless power transmission from a bottom hole assembly of a drill string. The system has a downhole component having a wireless power transmitter adapted to wirelessly transmit at least one wireless power transmission and a wireless power receiver adapted to receive the at least one wireless power transmission.

Abstract: A method of determining anisotropy in a borehole is disclosed. An array of measurements along the borehole is obtained and a first depth in the borehole is selected. An arbitrary plane oriented with respect to the borehole at the first depth is designated and an anisotropy for the first depth with respect to the arbitrary plane is determined. The arbitrary plane is repositioned at the first depth and an anisotropy for different positions of the arbitrary plane at the first depth is determined. A minimum anisotropy coefficient with respect to the arbitrary plane at the first depth is identified based on anisotropy for different positions of the arbitrary plane. An anisotropy tensor for the first depth is then identified.

Abstract: A method for measuring the resistivity of geologic formations is described. An electromagnetic field may be generated using at least one stationary long-range transmitter. The frequency of the electromagnetic field may be between and/or including the ULF/ELF range. At least one component of the electromagnetic field may be measured by land, marine, and/or airborne receiver. A conductivity distribution may be determined based on the at least one measured component. The determined conductivity distribution may be correlated with geological formations and/or hydrocarbon deposits.

Abstract: A stabilized field sensor apparatus collects field data, in particular magnetic field data, with reduced motion noise. The apparatus includes a tear drop shaped housing, a tow frame in the housing, a plurality of vibration isolating dampers spaced around the frame, a base assembly mounted to the dampers, a support pedestal having a bottom end fixed to the base assembly and an upper free end, a single spherical air bearing connected to the upper free end of the pedestal, an instrument platform with a lower hollow funnel having an upper inside apex supported on the air bearing for a one point support, principal and secondary gyro stabilizers for maintaining pivotal and rotational stability, and at least one field sensor mounted to the instrument platform for collecting the field data while being stabilized against motion noise including vibration, pivoting and rotation from the base assembly, from the tow frame and from the housing.

Abstract: An apparatus for detecting a position of a component in an earth formation is disclosed. The apparatus includes: a transmitter configured to emit a first magnetic field into the earth formation and induce an electric current in the component, the transmitter having a first magnetic dipole extending in a first direction; and a receiver for detecting a second magnetic field generated by the component in response to the first magnetic field, the receiver having a second magnetic dipole extending in a second direction orthogonal to the first direction. A method and computer program product for detecting a position of a component in an earth formation is also disclosed.

Abstract: An apparatus for evaluating an earth formation, the apparatus including: a logging tool configured to be conveyed through a borehole penetrating the earth formation; a coil inductively coupled to the earth formation, the coil being disposed at the logging instrument; and a circuit coupled to the coil wherein the circuit and the coil form an oscillator circuit, the oscillator circuit being configured to oscillate when a circuit parameter of the oscillator circuit satisfies an oscillation criterion, the circuit parameter being related to a property of the earth formation.

Abstract: A method for electromagnetic surveying subsurface formations includes inducing an electromagnetic field in the subsurface formations by passing electric current through a transmitter. Response of the subsurface formations to the induced electromagnetic field is detected at a first plurality of spaced apart positions disposed longitudinally within a bipole length of the transmitter. A direct induction response is removed from the detected response.

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 method for electromagnetic exploration includes imparting a first electromagnetic signal into subsurface formations from a first location and imparting a second electromagnetic signal into the formations from a second location substantially contemporaneously with imparting the first electromagnetic signal. The first and second electromagnetic signals are substantially uncorrelated with each other. A combined electromagnetic response of the formations to the first and second imparted electromagnetic signals is detected at a third location. A response of the formations to each of the first and the second imparted signals is determined from the detected response.

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: A method for measuring the resistivity of sea-bed formations is described. An electromagnetic field is generated using at least one stationary long-range transmitter. The frequency of the electromagnetic field is between and/or including the ULF/ELF range. At least one component of the electromagnetic field is measured. A conductivity distribution is determined based on the at least one measured component. The determined conductivity distribution is correlated with geological formations and/or hydrocarbon deposits.

Abstract: A system for measuring a true vertical depth of a downhole tool is provided. The system includes: a first optical clock located at a first depth and having a first frequency; a second optical clock disposable at a downhole location and having a second frequency at the downhole location; and a processor for receiving the first frequency and the second frequency, and calculating a true vertical depth of the second optical clock based on a difference between the first frequency and the second frequency. A system and computer program product for measuring a true vertical depth of a downhole tool are also provided.

Abstract: A method for determining reservoir formation properties that consists of exciting the reservoir formation with an electromagnetic exciting field, measuring an electromagnetic signal produced by the electromagnetic exciting field in the reservoir formation, extracting from the measured electromagnetic signal a spectral complex resistivity as a function of frequency, fitting the spectral complex resistivity with an induced polarization model and deducing the reservoir formation properties from the fitting with the induced polarization model.

Abstract: Disclosed are embodiments of methods and systems for wireless data transmission by magnetic induction. In one embodiment, a network of magnetic induction units is provided. The units may be configured to transmit a data signal by modulation of a time-varying magnetic field. One or more units may also be configured to receive a data signal received from another magnetic induction unit. In one specific implementation, a network of underground magnetic induction units is provided, each having a sensor connected thereto. Each of the units, or a subset of the units, may be configured to transmit its sensed data to an adjacent or nearby unit, which, in turn, may retransmit the original data, along with additional appended data, to another adjacent unit. The network data may thereby be relayed in a multi-hop fashion until it reaches a desired destination.

Abstract: A method for measuring the resistivity of geologic formations is described. An electromagnetic field may be generated using at least one stationary long-range transmitter. The frequency of the electromagnetic field may be between and/or including the ULF/ELF range. At least one component of the electromagnetic field may be measured by land, marine, and/or airborne receiver. A conductivity distribution may be determined based on the at least one measured component. The determined conductivity distribution may be correlated with geological formations and/or hydrocarbon deposits.

Abstract: A method for electromagnetic exploration includes imparting a first electromagnetic signal into subsurface formations and imparting a second electromagnetic signal into the formations substantially contemporaneously with imparting the first electromagnetic signal. The first and second electromagnetic signals are substantially uncorrelated with each other. A combined electromagnetic response of the formations to the first and second imparted electromagnetic signals is detected. A response of the formations to each of the first and the second imparted signals is determined from the detected response.

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: A suspension net is provided for distributing tension forces from a tow rope to an electromagnetic bird used for geophysical surveying. The suspension net allows large transmitter loop sizes, and the net structure generally avoids rope confusions that can occur during lift-up.

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: An electromagnetic receiver includes at least one sensor for measuring electromagnetic signals, and a calibration antenna configured to generate an electromagnetic signal at a first frequency.

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 method for measuring the resistivity of sea-bed formations is described. An electromagnetic field is generated using at least one stationary long-range transmitter. The frequency of the electromagnetic field is between and/or including the ULF/ELF range. At least one component of the electromagnetic field is measured. A conductivity distribution is determined based on the at least one measured component. The determined conductivity distribution is correlated with geological formations and/or hydrocarbon deposits.

Abstract: A source arrangement for generating electrogmagnetic (EM) wavefields, comprising an EM signal generator, at least three electrodes (141-144) connected to the generator, and a control system. The electrodes are spaced apart but not all in line. The control system is arranged to apply non-coincident time-varying signals or transmissions from the generator between different pairs of the electrodes. The non-coincidence can be by applying the signals sequentially or by applying the signals out of phase.

Abstract: An induction logging tool is used on a MWD bottom hole assembly. Due to the finite, nonzero, conductivity of the mandrel, conventional multi frequency focusing (MFF) does not work. A correction is made to the induction logging data to give measurements simulating a perfectly conducting mandrel. MFF can then be applied to the corrected data to give formation resistivities.

Abstract: A method and apparatus for minimizing direct coupling between transmitters and receivers on a downhole logging tool are disclosed. One embodiment includes a transmitter, a bucking device, and a plurality of receivers, where signals may be directly coupled from the transmitter into the receivers and signals may be indirectly coupled from the transmitter into the receivers through the formation and borehole environment. The bucking device minimizes the magnitude of the signals that are directly coupled from the transmitter into multiple receivers within the plurality. By varying the current in the bucking device, the bucking device minimizes the magnitude of the directly coupled signal of each receiver in the plurality, and each receiver may utilize a common bucking device.

Abstract: A coil arrangement and method of collecting and processing data in induction logging of wells is disclosed. The coil arrangement includes three essentially identical coils made of elliptical conductive loops lying in a plane tilted from the axis of the logging tool. Each coil is centered on the same point in space. Data are preferably collected by using the coil arrangement for both transmitter and receiver, and transmitting at three closely-spaced frequencies, one from each of the transmitter coils. The transmitted signals are received and recorded, at which time they are operated on mathematically to create rotation of an after-the-fact virtual sonde for measuring desired earth formation properties.