Electron paramagnetic resonance (EPR) techniques and apparatus for performing EPR spectroscopy on a flowing fluid

An electron paramagnetic resonance (EPR) spectrometer for performing EPR spectroscopy on a fluid from a flowing well, the EPR spectrometer comprising:

• a tube having a cavity capable of receiving the fluid;
• a magnetic field generator configured to generate a DC magnetic field in the fluid during operation of the EPR spectrometer;
• transmit circuitry configured to generate a radio frequency (RF) signal;
• a resonator coupled to the transmit circuitry and configured to convert the RF signal into an RF magnetic field in the fluid during the operation of the EPR spectrometer;
• receive circuitry configured to receive and process reflected signals from the fluid via the resonator;
• and
• at least one processor coupled to the magnetic field generator, the transmit circuitry, and the receive circuitry and configured, for a first EPR iteration, to:
• control the transmit circuitry to perform a first frequency sweep of discrete electromagnetic frequencies on the cavity containing the fluid;
• determine first parameter values of reflected signals from the first frequency sweep;
• select a first discrete frequency corresponding to one of the first parameter values that is less than a threshold value;
• control the transmit circuitry to activate a first electromagnetic field in the fluid at the first discrete frequency;
• and
• control the magnetic field generator, while the first electromagnetic field is activated, to perform a first DC magnetic field sweep to generate a first EPR spectrum.

A non-transitory computer-readable medium storing instructions that, when executed on a processor, perform operations for performing electron paramagnetic resonance (EPR) spectroscopy on a fluid from a flowing well, the operations comprising, for an EPR iteration:

• performing a frequency sweep of discrete electromagnetic frequencies on a cavity containing the fluid;
• determining parameter values of reflected signals from the frequency sweep;
• selecting a discrete frequency corresponding to one of the parameter values that is less than a threshold value;
• activating an electromagnetic field in the fluid at the discrete frequency;
• and
• while the electromagnetic field is activated, performing a DC magnetic field sweep to generate an EPR spectrum.