Rotating frame pulsed nuclear magnetic resonance spectroscopy

An apparatus for analyzing a sample of interest comprising:

• (a) a magnet for applying at least a static magnetic field across a sample volume that encompasses the sample of interest;
• (b) an RF antenna configured to produce radio-frequency pulses of oscillating magnetic field across the sample volume, wherein the radio-frequency pulses are characterized by a component transverse to the static magnetic field, and wherein the radio-frequency pulses are defined by a pulse sequence that includes a plurality of measurement segments that are configured to characterize properties of nuclear magnetization of the sample of interest;
• and
• (c) receiver circuitry for detecting signals induced by the radio-frequency pulses of oscillating magnetic field produced by the RF antenna in order to characterize the properties of nuclear magnetization of the sample of interest;
• wherein the plurality of measurement segments include at least one first-type measurement segment at least one second-type measurement segment, the first-type measurement segment configured to characterize relaxation of spin-lattice interaction between nuclei of the sample of interest in a rotating frame at a predefined frequency, and the at least one second-type measurement segment configured to characterize at least one other property of the sample of interest, the at least one other property of the sample of interest selected from the group including a relaxation property of the sample of interest in a laboratory frame and a diffusion property of the sample of interest.

A downhole NMR tool that is conveyable within a borehole, the downhole NMR tool for analyzing a sample of interest, the downhole NMR tool comprising:

• (a) a magnet for applying at least a static magnetic field across a sample volume encompassing the sample of interest;
• (b) an RF antenna configured to produce radio-frequency pulses of oscillating magnetic field across the sample volume, wherein the radio-frequency pulses are characterized by a component transverse to the static magnetic field, and wherein the radio-frequency pulses are defined by a pulse sequence that includes a plurality of measurement segments that are configured to characterize properties of nuclear magnetization of the sample of interest;
• (c) receiver circuitry for detecting signals induced by the radio-frequency pulses of oscillating magnetic field produced by the RF antenna in order to characterize the properties of nuclear magnetization of the sample of interest;
• and
• (d) electronics that are configured to vary amplitude of the radio-frequency pulses produced by the RF antenna.

A method for analyzing a sample of interest comprising:

• (a) while applying at least a static magnetic field across a sample volume that encompasses the sample of interest, applying radio-frequency pulses of oscillating magnetic field across the sample volume, wherein the radio-frequency pulses are characterized by a component in a plane transverse to the static magnetic field, and wherein the pulses are defined by a set of pulse sequences that include measurement segments configured to characterize relaxation of spin-lattice interaction between nuclei of the sample of interest in a rotating frame at a number of predefined frequencies;
• and
• (b) detecting signals induced by the radio-frequency pulses of oscillating magnetic field produced in (a) in order to derive a relaxation property of the sample of interest in the rotating frame for the number of predefined frequencies;
• (c) processing the signals detected in (b) by inversion to derive a plurality of distribution functions for a plurality of dimensions, wherein the plurality of dimensions correspond to the relaxation property of the sample of interest in the rotating frame for the number of predefined frequencies;
• and
• (d) generating a plot based upon the plurality of distribution functions derived in (c) for analysis of the sample of interest.