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 provided for investigating a downhole formation using a nuclear magnetic resonance (NMR) tool having two or more radio frequency receiving coils. 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 can be reconstructed to obtain an indication of a parameter of the formation at multiple locations along the length of the borehole.

Abstract: Apparatus and methods are provided for finding indications of at least one of a water fraction, a hydrocarbon fraction, water conductivity, and water salinity of a fluid. The fluid is within a flow line that extends through a resonator. The flow line is subjected to microwaves at multiple microwave frequencies injected into the resonator, with electric field lines parallel to the fluid flow line. A power detector is used at an output of the resonator, and a peak power and associated resonance frequency are used to find the indication(s) which may be plotted and displayed. In one embodiment, the resonator is a dual loop-gap resonator, and the microwave frequencies are generated by a microwave sweeper source at approximately 1 GHz.

Abstract: A method for correcting motion-effects from a downhole measurement includes, in one embodiment, determining relative motion of a downhole logging tool for a given logging operation in a borehole formed in an earth formation, determining a motion induced signal decay (MID) based upon the determined relative motion, determining a motion-effect inversion kernel (MEK) based upon the determined MID, using the downhole logging tool to acquire measurements that are affected by motion of the downhole logging tool during the logging operation, and using the MEK to process the acquired motion-affected measurements to obtain motion-corrected data. Corresponding systems, devices, and apparatuses are also disclosed herein.

Abstract: Methods are provided for identifying one or more transition characteristics in a hydrocarbon fluid such as asphaltene onset pressure (AOP), bubble point or dew point. A transition characteristic is determined by subjecting the fluid to different pressures or temperatures, conducting NMR tests at the different pressures or temperatures to obtain signals, processing the signals to obtain values of a function of an NMR parameter as a function of pressure or temperature, and analyzing the values to find a discontinuity that identifies the transition characteristic. In embodiments, the NMR parameters may include at least one of a relaxation parameter such as T2 or a T1-T2 ratio, a diffusion parameter and an initial magnetization parameter. In embodiments, dual linear fitting, Bayesian change point detection algorithms, and instantaneous slope analysis may be utilized to analyze the values in order to find a discontinuity.

Abstract: Methods for analyzing a formation samples using nuclear magnetic resonance (NMR) are described herein. One method includes performing an NMR measurement of the formation sample to obtain NMR data. The NMR measurement detects NMR signals with echo times of less than or equal to 100 microseconds. The NMR data is analyzed to determine a measure of organic hydrogen content of the formation sample, such as (i) total organic hydrogen content, (ii) kerogen content, (iii) bitumen content, and/or (iv) oil content.

Abstract: Methods and related apparatuses of a downhole micro nuclear magnetic resonance (NMR) device having a resonant tuning (LC) circuit for use in a formation for collecting NMR signals from a fluid in the formation while under downhole pressures and temperatures. The downhole micro NMR device includes: a micro tube for the flowing fluid to flow therethrough; at least one magnet disposed about the micro tube; and at least one micro RF coil structured and arranged approximate to the micro tube and tuned to a Larmor frequency corresponding to a applied magnetic field from the at least one magnet.

Abstract: Methods and related apparatuses of a downhole micro nuclear magnetic resonance (NMR) device having a resonant tuning (LC) circuit for use in a formation for collecting NMR signals from a fluid in the formation while under downhole pressures and temperatures. The downhole micro NMR device includes: a micro tube for the flowing fluid to flow therethrough; at least one magnet disposed about the micro tube; and at least one micro RF coil structured and arranged approximate to the micro tube and tuned to a Larmor frequency corresponding to a applied magnetic field from the at least one magnet.

Abstract: Methods and pulse sequences for facilitating nuclear magnetic resonance (NMR) measurements in grossly inhomogeneous fields. Methods and pulse sequences according to the invention may be used to accurately measure variables such as transverse relaxation time, longitudinal relaxation time, and diffusion, without the need for data at long recovery time, thereby allowing for faster measurements. In addition, methods and pulse sequences according to embodiment of the invention may allow simultaneous encoding of information in both the amplitude and the shape of echoes, so as to allow a single-shot measurement of multiple variables, e.g., both transverse relaxation time (from the decay of echo amplitudes) and longitudinal relaxation time (from the echo shape). CPMG detection may be used to overcome the often limited signal-to-noise ratio in grossly inhomogeneous fields.

Abstract: Methods and pulse sequences for facilitating nuclear magnetic resonance (NMR) measurements in grossly inhomogeneous fields. Methods and pulse sequences according to the invention may be used to accurately measure variables such as transverse relaxation time, longitudinal relaxation time, and diffusion, without the need for data at long recovery time, thereby allowing for faster measurements. In addition, methods and pulse sequences according to embodiment of the invention may allow simultaneous encoding of information in both the amplitude and the shape of echoes, so as to allow a single-shot measurement of multiple variables, e.g., both transverse relaxation time (from the decay of echo amplitudes) and longitudinal relaxation time (from the echo shape). CPMG detection may be used to overcome the often limited signal-to-noise ratio in grossly inhomogeneous fields.

Abstract: Methods and pulse sequences for facilitating nuclear magnetic resonance (NMR) measurements in grossly inhomogeneous fields. Methods and pulse sequences according to the invention may be used to accurately measure variables such as transverse relaxation time, longitudinal relaxation time, and diffusion, without the need for data at long recovery time, thereby allowing for faster measurements. In addition, methods and pulse sequences according to embodiment of the invention may allow simultaneous encoding of information in both the amplitude and the shape of echoes, so as to allow a single-shot measurement of multiple variables, e.g., both transverse relaxation time (from the decay of echo amplitudes) and longitudinal relaxation time (from the echo shape). CPMG detection may be used to overcome the often limited signal-to-noise ratio in grossly inhomogeneous fields.

Abstract: Methods and pulse sequences for facilitating nuclear magnetic resonance (NMR) measurements in grossly inhomogeneous fields. Methods and pulse sequences according to the invention may be used to accurately measure variables such as transverse relaxation time, longitudinal relaxation time, and diffusion, without the need for data at long recovery time, thereby allowing for faster measurements. In addition, methods and pulse sequences according to embodiment of the invention may allow simultaneous encoding of information in both the amplitude and the shape of echoes, so as to allow a single-shot measurement of multiple variables, e.g., both transverse relaxation time (from the decay of echo amplitudes) and longitudinal relaxation time (from the echo shape). CPMG detection may be used to overcome the often limited signal-to-noise ratio in grossly inhomogeneous fields.

Abstract: A method for tuning a nuclear magnetic resonance (NMR) tool having an operating frequency and equipped with an antenna, is disclosed comprising: (a) transmitting a rf magnetic field to a sample under investigation; (b) receiving an NMR signal from the sample within a detection window; (c) determining mistuning of said antenna relative to said operating frequency; (d) analyzing the received echo signal to determine mistuning of the received signal from the operating frequency. The mistuning of the received signals from the operating frequency may be determined by analyzing any changes in phase of the echo along the echo signal. The antenna tuning process may be automated by measuring calibrated signal amplitudes at more than one frequency and identifying a maximum amplitude. The system tuning may be maintained by repeating (a) through-(d) while operating the tool and implementing a feedback loop.