Embodiments described herein generally relate to systems, tools, and methods for flow assurance monitoring within pipe structures. In an embodiment is provided a method of determining at least one property of a mixture flowing through a system that includes introducing an inhibitor to a fluid flowing through the system to form the mixture; exposing the mixture to electromagnetic energy to induce at least one paramagnetic response from at least one diamagnetic species present in the mixture flowing through the system; performing electron paramagnetic resonance (EPR) spectroscopy on the at least one paramagnetic response to generate an EPR spectrum; and determining the at least one property of the mixture based on the EPR spectrum. Apparatus for determining fluid properties and systems for extracting hydrocarbons from a subterranean reservoir are also provided.

Embodiments described herein generally relate to systems, tools, and methods for flow assurance monitoring within pipe structures. In an embodiment is provided a method of determining at least one property of a mixture flowing through a system that includes introducing an inhibitor to a fluid flowing through the system to form the mixture; exposing the mixture to electromagnetic energy to induce at least one paramagnetic response from at least one diamagnetic species present in the mixture flowing through the system; performing electron paramagnetic resonance (EPR) spectroscopy on the at least one paramagnetic response to generate an EPR spectrum; and determining the at least one property of the mixture based on the EPR spectrum. Apparatus for determining fluid properties and systems for extracting hydrocarbons from a subterranean reservoir are also provided.

A magnetometer that finds a magnitude of an ambient magnetic field, comprising: a) a diamond cubic structure crystal, with an ensemble of paramagnetic defects oriented along each of the crystal's four tetrahedral axes; b) a microwave source that produces a microwave field at the crystal, of controllable frequency over a range that includes microwave resonance frequencies of paramagnetic defects oriented along all four axes; c) a light source that illuminates the paramagnetic defects with light that causes fluorescent emission from the paramagnetic defects; d) a light detector that measures the fluorescent emission; and e) a controller configured to: 1) measure the fluorescent emission at different microwave frequencies within the range, to obtain a spectrum of the paramagnetic defect ensemble; 2) calculate a variance property of the spectrum; and 3) calculate the magnitude of the ambient magnetic field from the variance property.

A hydrogen gas sensor utilizing electrically isolated tunneling magnetoresistive sensing elements is provided. The hydrogen gas sensor comprises: a substrate in an X-Y plane, tunneling magnetoresistive sensors located on the substrate, and a hydrogen sensing layer located on the tunnel magnetoresistive sensors. The hydrogen sensing layer and the tunneling magnetoresistive sensor are electrically isolated from each other. The hydrogen sensing layer includes a multi-layer thin film structure formed from palladium layers and ferromagnetic layers, wherein the palladium layers are used for absorbing hydrogen in the air that causes a change in the orientation angle of a magnetic anisotropy field in each of the ferromagnetic layers in the X-Z plane into an X-axis direction. The tunnel magnetoresistive sensors are used for detecting a magnetic field signal of the hydrogen sensing layer, wherein the magnetic signal determines the hydrogen gas concentration. This hydrogen gas sensor ensures measurement safety.

Improved loop-gap resonators applicable to Electron-Spin Resonance spectroscopy and to quantum computing employ interdigitated capacitor structures to dramatically increase the capacitance of the resonator, along with corresponding decreases in loop size to enable measurements of small-volume samples or individual quantum bits (qubits). The interdigitated-capacitor structures are designed to minimize parasitic inductance.

A ferromagnetic resonance (FMR) measurement method is disclosed wherein a magnetic film or stack of layers is patterned into elongated structures having a length along a long axis. A magnetic field (H) is applied in two different orientations with respect to the long axis (in-plane parallel and perpendicular to the long axis) or one orientation may be perpendicular-to-plane. In another embodiment, H is applied parallel to a first set of elongated structures with a long axis in the x-axis direction, and perpendicular to a second set of elongated structures with a long axis in the y-axis direction. From the difference in measured resonance frequency (Δfr) (for a fixed magnetic field and sweeping through a range of frequencies) or the difference in measured resonance field (ΔHr) (for a fixed microwave frequency and sweeping through a range of magnetic field amplitudes), magnetic saturation Ms is determined using formulas of demagnetizing factors.

A method of detecting spins in a sample, includes exciting the spins of the sample by means of a radio-frequency or microwave electromagnetic pulse for flipping the spins, and detecting a noise signal produced by the return of the spins to equilibrium by means of a device for counting radio-frequency or microwave photons.

A method of detecting spins in a sample, includes exciting the spins of the sample by means of a radio-frequency or microwave electromagnetic pulse for flipping the spins, and detecting a noise signal produced by the return of the spins to equilibrium by means of a device for counting radio-frequency or microwave photons.

A magnetic measuring device includes: a determination part configured to identify four maximum inclination points in an average value in a visual field of a light detection magnetic resonance spectrum and configured to determined a degree of decrease in relative fluorescence intensity and a microwave frequency at each of the maximum inclination points; a setting part configured to set a reference decrease degree of the relative fluorescence intensity in a predetermined area and configured to set operating point frequency initial values at four points at which the reference decrease degree is achieved, near the microwave frequencies at the respective maximum inclination points; a frequency update part configured to update operating point frequencies at the four points; and a frequency correction part configured to input the updated operating point frequencies to a microwave oscillator as corrected operating point frequencies.

Certain aspects of the present disclosure provide methods and apparatus for closed-loop control of a system using one or more electron paramagnetic resonance (EPR) sensors located on-site. With such EPR sensors, a change can be applied to the system, the EPR sensors can measure the effect(s) of the change, and then adjustments can be made in real-time. This feedback process may be repeated continuously to control the system.