Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In an embodiment is provided a method of determining at least one property of a fluid that includes inducing a paramagnetic response from at least one diamagnetic species flowing through a system, the fluid including the at least one diamagnetic species; performing electron paramagnetic resonance (EPR) spectroscopy on at least a portion of the fluid to generate an EPR spectrum; and determining at least one property of the fluid based on the EPR spectrum. In another embodiment is provided a method of determining at least one property of a first fluid that includes introducing an inhibitor composition to a first fluid flowing through a system to form a second fluid; performing EPR spectroscopy on at least a portion of the second fluid to generate an EPR spectrum; and determining at least one property of the second fluid based on the EPR spectrum. Apparatus for determining fluid properties are also provided.

Abstract: 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.

Abstract: 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.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for sensing a fluid flowing in a conduit using a mobile electron paramagnetic resonance (EPR) device. The mobile EPR device may include one or more EPR sensors for making EPR measurements and, for certain aspects, may include one or more other sensors for making other measurements. One example mobile EPR device for deploying in a conduit generally includes a housing configured to be conveyed by a fluid flowing in the conduit; a bore in the housing for receiving the fluid; and an EPR sensor disposed adjacent to the bore for EPR sensing of the fluid as the mobile EPR device traverses a section of the conduit.

Abstract: 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.