A method for wireline or logging-while-drilling systems that uses pulsed neutron sources coupled to multiple dual-function radiation detectors of neutrons and gamma rays, as well as a non-transitory computer readable memory device that can distinguish using pulse shape discrimination techniques the neutrons from the gamma rays in order to measure thermal neutron time-decay signals and thermal neutron capture gamma ray time-decay signals that are later further process using the non-transitory computer readable memory device to obtain a borehole sigma and formation sigma that are not affected by near-wellbore environments.

Systems and methods employed measure borehole density by neutron induced gammas using a pulsed neutron tool. Traditional nuclear density methods only measure a bulk average density of the surrounding material. As discussed below, methods to measure only the borehole density excluding the contamination from the formation are disclosed. Specifically, the proposed methods use unique signatures from each geometric region to directly measure the borehole density or compensate for the contamination from formation. This method may be achieved by a borehole density measurement using differential attenuation of capture gamma from casing iron, a borehole density measurement using differential attenuation of inelastic gamma from oxygen, a differential attenuation of any induced gamma from any element from borehole and formation, or any combination thereof.

A method for obtaining a gas saturation value of a subterrain formation involves a tool having multiple dual-function detectors that detect neutrons and gamma rays. The method includes steps of emitting neutrons into the formation, detecting neutrons and gamma ray signals form the formation using the detectors, determining formation parameters including the formation type and formation porosity, and further determining parameters such as the ratio of thermal neutron count rates from at least two of three detectors, the ratio of capture gamma count rates from at least two of three detectors, and calculating the real-time gas saturation value using the determined parameters.

Downhole neutron generators, downhole logging tools that utilize neutron generators, and methods to auto tune downhole neutron generators are disclosed. While a neutron generator is deployed in a borehole of a wellbore, the method includes determining whether an oscillation cycle of an ion beam current generated by the neutron generator is stable. After a determination that the oscillation cycle of the ion beam current is stable, the method includes determining proportional, integral, and derivative parameters of a proportional-integral-derivative controller that is operable to adjust an amount of power supplied to generate ions. The method further includes adjusting a replenish voltage of a replenish power supply of the neutron generator based on the proportional, integral, and derivative parameters.

The present disclosure relates to a downhole tool that includes a first photon flux detector disposed at a first radial position about a longitudinal axis of the downhole tool that measures a first signal indicative of an x-ray flux of the x-ray photons. The downhole tool also includes a second photon flux detector disposed at a second radial position about the longitudinal axis of the downhole tool that measures a second signal indicative of the x-ray flux of the x-ray photons. Further, the downhole tool includes a controller communicatively coupled to the first photon flux detector and the second photon flux detector that determines a condition associated with the electron beam based at least in part on a relative x-ray flux from the first photon flux detector and the second photon flux detector.

The present disclosure relates to a downhole tool that includes a first photon flux detector disposed at a first radial position about a longitudinal axis of the downhole tool that measures a first signal indicative of an x-ray flux of the x-ray photons. The downhole tool also includes a second photon flux detector disposed at a second radial position about the longitudinal axis of the downhole tool that measures a second signal indicative of the x-ray flux of the x-ray photons. Further, the downhole tool includes a controller communicatively coupled to the first photon flux detector and the second photon flux detector that determines a condition associated with the electron beam based at least in part on a relative x-ray flux from the first photon flux detector and the second photon flux detector.

Systems and methods of the present disclosure relate to determining a borehole holdup. A method comprises logging a well with a pulsed-neutron logging (PNL) tool; receiving, via the PNL tool, transient decay measurements, capture spectrum measurements, and inelastic spectrum measurements; extracting information from each of the capture spectrum measurements, the inelastic spectrum measurements, and the transient decay measurements; inputting all of the extracted information as a single input into artificial neural networks; and determining the borehole holdup with the artificial neural networks.

A system and methods for electrolysis of saline solutions are provided. An exemplary method provides simulating temperature gradients of reservoir fluids at different well conditions in a well, wherein the reservoir fluids include oil and water. A total flow rate of the reservoir fluids is quantified based on the simulated temperature gradients, and a water flow rate of water in the reservoir fluids is calculated based on, at least in part, a pulsed neutron log. An oil flow rate is calculated from the total flow rate of the reservoir fluids and the water flow rate.

Systems and methods for determining holdup in a wellbore using a neutron-based downhole tool. In examples, the tool includes nuclear detectors that may measure gammas induced by highly energized pulsed-neutrons emitted by a generator. The characteristic energy and intensity of detected gammas indicate the elemental concentration for that interaction type. A detector response may be correlated to the borehole holdup by using the entire spectrum or the ratios of selected peaks. As a result, measurements taken by the neutron-based downhole tool may allow for a two component (oil and water) or a three component (oil, water, and gas) measurement. The two component or three component measurements may be further processed using machine learning (ML) and/or artificial intelligence (AI) with additional enhancements of semi-analytical physics algorithms performed at the employed network's nodes (or hidden layers).

The present disclosure is directed to methods for evaluating a gravel pack, a frac-pack, or cement in a wellbore. In at least one embodiment, a method for evaluating a gravel pack, frac-pack or cement in a wellbore, includes pumping a first material into the wellbore, wherein the first material comprises a first tracer that is not radioactive. The method includes pumping a second material into the wellbore, wherein the second material comprises a second tracer that is not radioactive. The method includes obtaining a set of data using the downhole tool in the wellbore after the first and second materials are pumped into the wellbore. The method includes obtaining a baseline using the downhole tool in the wellbore in a depth interval without the first or second material. The method includes comparing the set of data with the baseline.