A method for calculating a magnetic influence factor (MIF) between an atom and a resonant atom of a molecule of a material includes determining a current magnetic field strength at a test location above a quantity of material buried at the test location, transmitting a test signal from an antenna at the test location, the test signal comprising a test fundamental frequency, and detecting, at the test location, a reflected wave comprising the test fundamental frequency on the antenna. The method includes varying the test fundamental frequency while retransmitting the test signal and detecting a reflected wave until reflected waves of various test frequencies are detected and identifying from the detected reflected waves a resonant frequency corresponding to a maximum magnitude of the detected reflected waves. The material includes molecules with a resonant atom and at least one atom different than the resonant atom.

A method for calculating a magnetic influence factor (MIF) between an atom and a resonant atom of a molecule of a material includes determining a current magnetic field strength at a test location above a quantity of material buried at the test location, transmitting a test signal from an antenna at the test location, the test signal comprising a test fundamental frequency, and detecting, at the test location, a reflected wave comprising the test fundamental frequency on the antenna. The method includes varying the test fundamental frequency while retransmitting the test signal and detecting a reflected wave until reflected waves of various test frequencies are detected and identifying from the detected reflected waves a resonant frequency corresponding to a maximum magnitude of the detected reflected waves. The material includes molecules with a resonant atom and at least one atom different than the resonant atom.

A method for determining the porosity of a core sample can include: saturating a core sample with a nuclear magnetic resonance (NMR) saturation fluid, wherein the core sample has a permeability of 100 milliDarcy (mD) or less, to achieve a saturated core sample; taking a NMR measurement of fluids in the saturated core sample; determining a porosity of the core sample based on a correlation between the NMR measurement and a NMR signal to fluid volume calibration.

A method for determining the porosity of a core sample can include: saturating a core sample with a nuclear magnetic resonance (NMR) saturation fluid, wherein the core sample has a permeability of 100 milliDarcy (mD) or less, to achieve a saturated core sample; taking a NMR measurement of fluids in the saturated core sample; determining a porosity of the core sample based on a correlation between the NMR measurement and a NMR signal to fluid volume calibration.

Certain aspects of the present disclosure provide methods and apparatus for performing electron paramagnetic resonance (EPR) spectroscopy on a fluid from a flowing well, such as fluid from hydrocarbon recovery operations flowing in a downhole tubular, wellhead, or pipeline. One example method generally includes, for a first EPR iteration, performing a first frequency sweep of discrete electromagnetic frequencies on a cavity containing the fluid; determining first parameter values of reflected signals from the first frequency sweep; selecting a first discrete frequency corresponding to one of the first parameter values that is less than a threshold value; activating a first electromagnetic field in the fluid at the first discrete frequency; and while the first electromagnetic field is activated, performing a first DC magnetic field sweep to generate a first EPR spectrum.

Certain aspects of the present disclosure provide methods and apparatus for performing electron paramagnetic resonance (EPR) spectroscopy on a fluid from a flowing well, such as fluid from hydrocarbon recovery operations flowing in a downhole tubular, wellhead, or pipeline. One example method generally includes, for a first EPR iteration, performing a first frequency sweep of discrete electromagnetic frequencies on a cavity containing the fluid; determining first parameter values of reflected signals from the first frequency sweep; selecting a first discrete frequency corresponding to one of the first parameter values that is less than a threshold value; activating a first electromagnetic field in the fluid at the first discrete frequency; and while the first electromagnetic field is activated, performing a first DC magnetic field sweep to generate a first EPR spectrum.

A method for calculating a magnetic influence factor (MIF) between an atom and a resonant atom of a molecule of a material includes determining a current magnetic field strength at a test location above a quantity of material buried at the test location, transmitting a test signal from an antenna at the test location, the test signal comprising a test fundamental frequency, and detecting, at the test location, a reflected wave comprising the test fundamental frequency on the antenna. The method includes varying the test fundamental frequency while retransmitting the test signal and detecting a reflected wave until reflected waves of various test frequencies are detected and identifying from the detected reflected waves a resonant frequency corresponding to a maximum magnitude of the detected reflected waves. The material includes molecules with a resonant atom and at least one atom different than the resonant atom.

A method and microfluidic device to perform reservoir simulations using pressure-volume-temperature (“PVT”) analysis of wellbore fluids.

A method and microfluidic device to perform reservoir simulations using pressure-volume-temperature (“PVT”) analysis of wellbore fluids.

Systems, methods, and apparatuses for determining pore volume and pore volume compressibility of secondary porosity in rock samples is disclosed. In some implementations, determining a pore volume of a secondary porosity in a rock core sample may include saturating the rock sample with deuterium oxide (D2O) by applying a vacuum to the core sample covered by D2O; centrifuging the saturated rock sample at a selected rotational speed in the presence of a second fluid to displace a portion of the D2O from the rock sample with the second fluid; measuring the rock sample with low-field .sup.1H nuclear magnetic resonance (NMR) to determine a volume of the second fluid within the rock sample; and determining a pore volume associated with a secondary porosity based on the volume of the second fluid within the rock sample.