Abstract: A method can include accessing a measurement model in memory of a downhole tool; determining an optimal parameter set using a processor of the downhole tool and the measurement model; and performing at least one measurement using at least one sensor of the downhole tool operated according to the optimal parameter set.

Abstract: Illustrative embodiments are directed to applying a nuclear magnetic resonance sequence to a substance within an inhomogeneous static magnetic field. Various embodiments include applying a series of refocusing pulses to the substance, each refocusing pulse in the series of refocusing pulses having at least two segments, and a total pulse duration less than or equal to approximately 1.414 times T180. Various embodiments can further include applying an excitation pulse to the substance in the inhomogeneous static magnetic field, where the excitation pulse generates an initial magnetization that is aligned with a refocusing axis produced by a refocusing cycle that is performed after the excitation pulse.

Abstract: Nuclear magnetic resonance (NMR) relaxation and/or diffusion measurements are used to deduce fluid compositional information such as a chain-length distribution, which may then be used to predict the true boiling points (TBP) of a sample of a complex hydrocarbon fluid mixture, such as a crude oil. The NMR measurements may be considered a fast and portable proxy measurement in estimating fluid TBP distributions in lieu of distillation methods, or the simulated distillation by gas chromatography.

Abstract: Systems and methods for monitoring a crude oil blending process use nuclear magnetic resonance (NMR) sensors which investigate properties of a plurality of crude oil streams that are mixed together to form a crude oil blend. An NMR sensor is also used to investigate the properties of the crude oil blend. The investigated properties may include viscosity. Resulting determinations may be used to control the input streams so that the output stream meets desired criteria. Additional sensors such as spectroscopy sensors, viscometers, and densitometers may be used in conjunction with the NMR sensors.

Abstract: Small-sized flowlines are provided for use in NMR apparatus. The small-sized flowlines can have a channel with an inner diameter or maximum width of less than 0.2 inch and can be made of sapphire, yttria-stabilized zirconia (YSZ), or extruded polyether ether ketone (PEEK), which are useful in high temperature, high pressure environments such as downhole in a geological formation.

Abstract: A method for measuring one or more properties of a formation includes applying a magnetic field to a subterranean formation using a downhole tool. A radiofrequency signal is transmitted into the subterranean formation that is exposed to the magnetic field. The radiofrequency signal induces a transverse magnetization in the subterranean formation, and the transverse magnetization induces an initial voltage signal in the downhole tool. The initial voltage signal is amplified using a first amplifier in the downhole tool such that the first amplifier outputs a first amplified voltage signal. The first amplified voltage signal is introduced to an input of the first amplifier, such that the first amplifier amplifies the first amplified voltage signal and outputs a second amplified voltage signal.

Abstract: Downhole properties of a geological formation may be determined using nuclear magnetic resonance (NMR) measurements obtained by a moving tool. To do so, an interpretation of the NMR data obtained by the moving data may take into account a moving model, characterization, or calibration of the downhole NMR tool. Additionally or alternatively, a partial interpretation mask may exclude interpretation of certain areas of data (e.g., T1-T2 data points or diffusion-T2 data points) that are expected to be less likely to describe downhole materials of interest.

Abstract: An apparatus for measuring nuclear magnetic resonance (NMR) properties of subsurface formations includes a magnet for pre-polarizing nuclear spins in the formations. A plurality of transmitter antennas is spaced apart along a length of the apparatus. The apparatus includes at least one of a receiver circuit selectively coupled to at least one of the plurality of transmitter antennas and a separate receiver antenna. The apparatus includes circuitry for applying radio frequency current pulses selectively to each of the plurality of transmitter antennas such that during a NMR measurement sequence while the apparatus is moving substantially only those of the plurality of transmitter antennas having radio frequency current pulses applied thereto are disposed longitudinally along a same region of interest in the subsurface formations.

Abstract: Systems and methods are described herein for investigating a downhole formation using a nuclear magnetic resonance (NMR) tool. The tool includes multiple detectors spaced along an axis parallel to a length of the wellbore. While the tool is moving through the wellbore, NMR pulse sequences are applied to the formation and resulting NMR signals are detected by the detectors. The data obtained over a period of time by the multiple detectors are inverted together to obtain an indication of a parameter of the formation at multiple locations along the length of the wellbore.

Abstract: A coaxial nuclear magnetic resonance (NMR) probe and related methods are described herein. The coaxial NMR probe includes a housing with a fluid inlet, a fluid outlet, a longitudinal axis, and an interior volume. The housing contains a fluid sample that is analyzed by the probe. The coaxial NMR probe also includes an elongated conductor disposed along the longitudinal axis of the housing. The elongated conductor generates an oscillating electromagnetic field within the interior volume of the housing. The oscillating electromagnetic field produces a NMR signal within the fluid sample. The elongated conductor may also be used to receive this NMR signal. The NMR signal is then analyzed to determine information about the fluid sample. Various NMR pulse sequences for use with this coaxial probe and other coaxial probes are also described herein.

Abstract: Magnet design is provided. A method customizes a magnetic field uniformity of a magnet by introducing one or more gaps between pieces of the magnet assembly.

Abstract: A nuclear magnetic resonance (NMR) system that uses a feedback induction coil to detect NMR signals generated within a substance is described herein. In one embodiment, the NMR system uses the Earth's magnetic field in conjunction with a transmitter coil that applies NMR sequences to a formation. The NMR sequences generate a weak NMR signal within the formation due to the weakness of the Earth's magnetic field. This weak NMR signal is detected using the feedback induction coil.

Abstract: A technique utilizes spatially resolved temperature measurements to infer the temperature of a subsea infrastructure. According to an embodiment, temperature data, e.g. a temperature map, is determined for the subsea infrastructure and comprises performing remote temperature measurements of water surrounding the subsea infrastructure. Additionally, a metrological scan of the subsea structure may be obtained. Furthermore, a simulation or simulations may be run for an assumed temperature profile along a surface of the subsea infrastructure. The data obtained from the remote temperature measurements, the metrological scan, and the simulation is processed to determine a temperature profile of the subsea infrastructure. This temperature profile can then be used to facilitate a variety of subsea infrastructure management decisions.

Abstract: Systems and methods for generating a multi-dimensional distribution function. First data and second data may be received in response to one or more radiofrequency pulses that are transmitted into a subterranean formation. The first data may include Carr-Purcell-Meiboom-Gill data, and the second data may include diffusion editing data with initial echo spacings longer than subsequent echo spacings. The second data may be inverted. A multi-dimensional distribution function may be determined using the inverted second data.

Abstract: A method and system for determining a property of a substance using nuclear magnetic resonance (NMR) is described herein. The method includes applying a NMR pulse sequence to the substance. The NMR pulse sequence includes a first set of pulses and a second set of pulses. The first set of pulses and the second set of pulses encode for overlapping diffusion times. By overlapping diffusion times, the NMR pulse sequence can be used to measure a diffusion coefficient for a first diffusion time, a diffusion coefficient for a second diffusion time, and a correlation between the two overlapping diffusion times. This information, in turn, can be used to differentiate between intrinsic bulk diffusivity of the substance and the reduced diffusivity of the substance caused by restricted diffusion.

Abstract: Systems and methods are provided for investigating a downhole formation using a nuclear magnetic resonance (NMR) tool. While the tool is moving through the borehole, the formation is magnetized and resulting signals are obtained. In accordance with the present approach, the acquired signals can be resolved azimuthally and/or laterally and can be reconstructed to obtain an indication of a parameter of the formation at multiple locations along the length of the borehole.

Abstract: Methods and systems are provided for tools having non-resonant circuits for analyzing a formation and/or a sample. For example, nuclear magnetic resonance and resistivity tools can make use of a non-resonant excitation coil and/or a detection coil. These coils can achieve desired frequencies by the use of switches, thereby removing the requirement of tuning circuits that are typical in conventional tools.

Abstract: An integrated circuit is provided for use in conjunction with an external antenna. The integrated circuit includes a memory circuit, a pulse sequencer, an NMR transmitter circuit and an NMR receiver circuit. The memory circuit is configured to store user-defined parameter data pertaining to an excitation period and an acquisition period that are part of an NMR pulse sequence. The pulse sequencer and the NMR transmitter circuit are configured to cooperate to generate RF signals in accordance the user-defined parameter data stored in the memory circuit, wherein such RF signals are supplied to the external antenna for emitting excitation signals from the external antenna during the excitation period of the NMR pulse sequence. The NMR receiver circuit is configured to receive electrical signals generated by the external antenna during the acquisition period of the NMR pulse sequence.

Abstract: A system and method for magnetic resonance imaging (MRI) of a subject employs an elongate housing configured to be held and manipulated in a user's hand. The housing supports at least one permanent magnet and at least one RF coil. A device positioning subsystem measures position and orientation of the housing. An electronic subsystem interfaces to the at least one RF coil and to the device positioning subsystem. The electronic subsystem is configured to i) execute pulse sequences where each pulse sequence transmits at least one RF pulse into body tissue of the subject and acquires MRI signals from the body tissue of the subject, ii) acquire position data representing position and orientation of the housing during the pulse sequences from the device positioning subsystem, and iii) process the MRI signals of i) together with the position data of ii) to derive an image of the body tissue of the subject.

Abstract: A method and system for determining a property of a substance using nuclear magnetic resonance (NMR) is described herein. The method includes applying a NMR pulse sequence to the substance. The NMR pulse sequence includes a first set of pulses and a second set of pulses. The first set of pulses and the second set of pulses encode for overlapping diffusion times. By overlapping diffusion times, the NMR pulse sequence can be used to measure a diffusion coefficient for a first diffusion time, a diffusion coefficient for a second diffusion time, and a correlation between the two overlapping diffusion times. This information, in turn, can be used to differentiate between intrinsic bulk diffusivity of the substance and the reduced diffusivity of the substance caused by restricted diffusion.