A method for separating oil-water two-phase NMR signals by using dynamic nuclear polarization comprising: using a combination of a non-selective free radical and a selective relaxation reagent to selectively enhance an NMR signal of an oil phase or a water phase, the relaxation reagent being capable of selectively suppressing dynamic polarization enhancement of the water phase or oil phase, thus achieving the polarization enhancement of a single fluid phase in the mixed fluid phases and realizing separation of the two-phase signals; or using a selective free radical to selectively enhance the NMR signal of the oil phase or the water phase, thus achieving the polarization enhancement of a single fluid phase in the mixed fluid phases and realizing separation of the oil-water two-phase NMR signals. The method is simple and easy to operate, has a short test time, and can efficiently separate NMR signals of oil and water phases.

This application is related to a system and methods for sampling fluids and gases using nuclear magnetic resonance (NMR) technology. Specifically the system is related to an improved metallic pipe design for use at oil and gas well heads that includes integral coils for transmitting an NMR pulse sequence and detecting NMR signals and can be used as a component of an NMR instrument. The methods are related to obtaining and analyzing NMR spectra in stationary and flowing states.

A side-looking Nuclear Magnetic Resonance (“NMR”) logging tool is designed to reduce and/or eliminate a borehole signal. The logging tool includes a magnet assembly having at least two magnets with magnetizations in different directions, thus resulting in a net magnetization that reduces the borehole signal.

Downhole nuclear magnetic resonance (NMR) methods that utilize oleophilic nanoparticle may allow for differentiation of light oil and oil-based filtrates. For example, a method may involve drilling a wellbore penetrating a subterranean formation using an oil-based drilling fluid that comprises an oil base fluid and a plurality of oleophilic nanoparticles; performing a plurality of NMR measurements at a plurality of depths of investigation (DOI) of a near-wellbore portion of the subterranean formation; and producing an invasion profile of an oil-based drilling fluid filtrate into the near-wellbore portion of the subterranean formation based on the plurality of NMR measurements.

Method of determining a velocity profile of a fluid flowing through a conduit, the method including applying a saturation pulse on spins of magnetic field-sensitive nuclei in the fluid, measuring a signal of the fluid to determine position of the magnetic field-sensitive nuclei, the measurement carried out at a recovery time ‘TR’ and at a distance ‘d’ within the conduit, determining within the conduit a radial distance ‘r’ characterized by a local minimum in the measured signal, wherein the radial distance ‘r’ is measured from the center of the conduit, and determining a velocity profile of the fluid at the radial distance, based on the magnetic field-sensitive nuclei.

A method for determining the solids content, fines content and/or particle size distribution of the solids in an oil sands process stream test sample comprising bitumen, solids and water using low-field time-domain NMR is provided which involves building a non-solids partial least squares calibration model using oil sands process streams calibration samples having a known bitumen content, solids content, water content, fines content and/or particle size distribution by subjecting the calibration samples to a first T.sub.1-weighted T.sub.2 measurement NMR pulse sequence that maximizes very fast relaxing signals and a second T1-weighted T2 measurement NMR pulse sequence that maximizes slow relaxing signals. The measurement of other sample properties strongly correlated with surface area, such as methylene blue index, can also be measured using a partial least squares calibration model.

Methods and systems for determining surface relaxivity from nuclear magnetic resonance measurements relate to applying multiple nuclear magnetic resonance (NMR) diffusion editing Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences to the porous medium, wherein the diffusion editing CPMG pulse sequences have a diffusion encoding time Δ; receiving NMR data generated by the pulse sequences; processing the received NMR data to obtain a distribution f(T.sub.2,D) for the diffusion encoding time Δ; repeating the applying, the receiving, and the processing at least one time for pulse sequences having different respective diffusion encoding times Δ to obtain respective distributions f(T.sub.2,D) corresponding respectively to the different diffusion encoding times Δ; and utilizing the respectively obtained distributions f(T.sub.2,D) to generate a surface relaxivity (ρ) determination.

Nuclear magnetic resonance (NMR) logging tools may be configured for situation-dependent NMR logging operations by including two dissimilar coils that may function in four different modes of operation based on logging conditions including: a resistivity of the fluid, a diameter of the wellbore, a depth into the subterranean formation of the volume of investigation, or a combination thereof. For example, an NMR logging tool with a z-coil and a transversal coil may be useful in generating in a volume of investigation of a subterranean formation either (1) a transversal radiofrequency (RF) excitation with the transversal coil or (2) a quadrature RF excitation with both the z-coil and the transversal coil, where the choice of transversal or quadrature RF excitation is based on the logging conditions; and detecting an NMR signal from the subterranean formation with one of: (1) the transversal coil or (2) both the z-coil and the transversal coil.

To measure the phase behavior of a fluid in a porous medium such as a tight gas shale, one illustrative method involves: (a) loading the fluid into a sample cell containing the porous medium; (b) setting a pressure and a temperature for the fluid in the sample cell; (c) applying an RF pulse sequence to the fluid in the sample cell to acquire an NMR signal; (d) deriving from the NMR signal an NMR parameter distribution that depends on the pressure and the temperature; (e) determining whether a fluid phase is present based on the NMR parameter distribution; (f) repeating operations (c) through (f) to determine the presence or absence of the fluid phase at multiple points along a pressure-temperature path that crosses a phase boundary; and (g) providing an estimated location of the phase boundary based on the presence or absence of the fluid phase at said points.

A method to produce a magnet arrangement, the method having steps of selecting a depth of investigation to be achieved by a downhole tool, identifying a desired magnetic field strength at the depth of investigation, producing a set of magnets to be incorporated into the downhole tool, sorting the set of magnets based on a quality of each of the magnets and optimizing the set of magnets such that the quality of each of the magnets results, when arranged, in the desired magnetic field strength at the depth of investigation and wherein the optimizing minimizes a cost function of the set of magnets produced.