The current invention is based, at least in part, on the finding that the transverse nuclear magnetic spin relaxation time T2 and the transverse nuclear magnetic spin relaxation rate R2, respectively, of protons of water molecules in an aqueous solution comprising viral particles depends on the loading status (full vs. empty) of the viral particle. Thus, one aspect of the current invention is a method for determining the ratio of loaded viral particles to empty viral particles in a sample, comprising the steps of determining a nuclear magnetic resonance (NMR) parameter related to the protons of the water molecules present in an aqueous solution comprising a mixture of loaded and empty viral particles by applying an NMR measurement to the solution, and determining the ratio of loaded viral particles to empty viral particles with the NMR parameter determined in the previous step based on a calibration function.

Methods for determining a volume of stored gas within a rock sample includes loading a rock sample into an overburden cell. A hydrocarbon gas at a gas pressure is applied to the rock sample and a confining fluid at a confining pressure is applied to the overburden cell. The confining pressure and the gas pressure are increased until a first pressure and temperature condition is met. With the rock sample maintained at the first temperature and pressure condition, a nuclear magnetic resonance spectrometer is used to scan the rock sample and measure a hydrocarbon gas volume within the rock sample. This measured hydrocarbon gas volume is then corrected using a Real Gas Index to determine the volume of stored gas within the rock sample.

A nuclear magnetic resonance (NMR) logging system and method is disclosed. The method may include obtaining an NMR well log, a measured downhole temperature, and at least one rock sample for a formation in a subsurface region. The method may further include determining an NMR distribution for each sample and selecting a set of samples based on the determined NMR distribution. For each selected sample, the method may further include determining a first parameter of the NMR distribution, a regression parameter of a relationship, and a first and second fractal parameters of the NMR distribution. The method may further include determining a second parameter of the NMR distribution based on the first and second fractal parameters, the regression parameter, and the downhole temperature. The method may still further include determining a parameter of the formation based on the second parameter of the NMR distributions of the set of samples.

Systems and methods for performing ungated magnetic resonance imaging are disclosed herein. A method includes producing magnetic resonance image MRI data by scanning a target in a low magnetic field with a pulse sequence having a spiral trajectory; sampling k-space data from respective scans in the low magnetic field and receiving at least one field map data acquisition and a series of MRI data acquisitions from the respective scans; forming a field map and multiple sensitivity maps in image space from the field map data acquisition; forming target k-space data with the series of MRI data acquisitions; forming initial magnetic resonance images in the image domain by applying a Non-Uniform Fast Fourier Transform to the target k-space data; and forming reconstructed images with a low rank plus sparse (L+S) reconstruction algorithm applied to the initial magnetic resonance images.

A method of estimating a wettability characteristic of a rock material includes acquiring a plurality of T2 distributions based on nuclear magnetic resonance (NMR) measurements of a rock material under a plurality of fluid saturated rock conditions, constructing a measurement matrix based on the plurality of T2 distributions, and performing non-negative factorization of the measurement matrix to determine feature components. The method also includes reconstructing the plurality of T2 distributions based on the feature components, and extracting a first set of T2 distributions associated with mobile water under a wetting condition and a second set of T2 distributions associated with mobile water under a non-wetting condition based on the feature components, and calculating a wettability index (WI) based on the first extracted set of T2 distributions and the second extracted set of T2 distributions.

A porosity model of a core sample obtained from a subterranean formation is determined. The porosity model includes a macroporosity group and a microporosity group. A nuclear magnetic resonance (NMR) measurement is performed to obtain an NMR T.sub.2 distribution of the core sample at 100% water saturation. A desaturation step is performed on the core sample. An NMR measurement is performed for the desaturation step to obtain an NMR T.sub.2 distribution of the core sample. A resistivity index of the subterranean formation is determined at least based on the porosity model and each of the NMR T.sub.2 distributions.

Method and system for determining a confinement size in a porous media, including subjecting the media to a substantially uniform static magnetic field, applying a magnetic resonance pulse sequence to the media, detecting magnetic resonance signals from the media, determining non-ground eigenvalues from the magnetic resonance relaxation spectrum, and determining a confinement size of the media from the eigenvalues.

A T.sub.1-T.sub.2* measurement which permits speciation of different components with restricted mobility in samples where a T.sub.1-T.sub.2 measurement is impossible is disclosed. Tracking the T.sub.1-T.sub.2* coordinate, and associated signal intensity changes, can reveal additional structural and/or dynamic information such as phase changes in rigid/semi-rigid biopolymer samples or pore level changes in morphology of the water environments in cement-based materials. In another aspect, the T.sub.1-T.sub.2* measurement may also be employed to discriminate composition in solid mixtures, a very significant analytical problem in industry. In a further aspect, the T.sub.1-T.sub.2* measurement has particular value in permitting a simple assignment of T.sub.1 to different T.sub.2* populations.

A method for determining a liquid portion of a flowing medium with a nuclear magnetic flowmeter includes: generating a gradient magnetic field in a measuring tube volume of the flowmeter; exposing the medium to the gradient magnetic field and a magnetic field generated by a magnetizing device of the flowmeter; generating and irradiating an excitation signal into the magnetized medium for exciting nuclear magnetic resonances therein; measuring nuclear magnetic resonances excited by the excitation signal in the magnetized medium as a measuring signal; determining frequencies of the nuclear magnetic resonances in the measuring signal; assigning the determined frequencies to positions along a first gradient direction in the measuring tube volume; assigning the nuclear magnetic resonances at the positions to liquid and gaseous portions of the medium; and determining a liquid portion of the medium in the measuring tube volume from the positions of the nuclear magnetic resonances.

A method of estimating a wettability characteristic of a rock and fluid system includes acquiring a sample of the rock material, performing a first nuclear magnetic resonance (NMR) measurement of the sample when the sample is in a full water saturation condition, and measuring a first T2 distribution, performing a second NMR measurement of the sample when the sample is in a second partial saturation condition, and measuring a second T2 distribution. The method also includes separating a hydrocarbon component of the second T2 distribution from a water component of the second T2 distribution, applying a fluid substitution model to the water component of the second T2 distribution to generate a computed T2 distribution, and calculating a wettability index (WI) based on a difference between the first T2 distribution and the computed T2 distribution.