Wellbore treatment compositions comprising non-radioactive tracer materials and methods for using the non-radioactive tracer materials to determine the location of treatment fluids within a subterranean formation are provided herein. A method comprising introducing a treatment fluid comprising a non-radioactive tracer material into a subterranean formation; exposing a portion of the subterranean formation to neutrons from a neutron source to activate the non-radioactive tracer material in the portion of the subterranean formation; and detecting gamma rays emitted by the activated tracer material in the portion of the subterranean formation.

A computer-implemented method that uses a preprogrammed neural network and a trained neural network computer program product to predict and then compared borehole and formation sigmas, when using a pulse neutron source and at least three dual-function radiation detectors. These dual-function radiation detectors are used for detecting both neutrons and gamma rays and further pre-programmed to distinguish between neutrons and gamma rays by using pulse shape discrimination techniques. The trained neural network computer program product can be used on above-surface systems, as well as below surface systems like borehole assemblies in logging-while-drilling systems. Once thermal neutron time-decay signals and capture gamma ray time-decay signals are measured by the at least three-dual function radiation detectors, a non-transitory computer readable memory device with the trained neural network computer program product is used to obtain a true borehole sigma and true formation sigma as the measurements are not affected by near-wellbore environments.

A computer-implemented method that uses a preprogrammed neural network and a trained neural network computer program product to predict and then compared borehole and formation sigmas, when using a pulse neutron source and at least three dual-function radiation detectors. These dual-function radiation detectors are used for detecting both neutrons and gamma rays and further pre-programmed to distinguish between neutrons and gamma rays by using pulse shape discrimination techniques. The trained neural network computer program product can be used on above-surface systems, as well as below surface systems like borehole assemblies in logging-while-drilling systems. Once thermal neutron time-decay signals and capture gamma ray time-decay signals are measured by the at least three-dual function radiation detectors, a non-transitory computer readable memory device with the trained neural network computer program product is used to obtain a true borehole sigma and true formation sigma as the measurements are not affected by near-wellbore environments.

Methods, tools, and systems for determining the lithium concentration of a formation traversed by a wellbore using pulsed neutron logging are described. Since determining lithium directly using pulsed neutron logging is problematic, this disclosure provides ways of determining lithium concentration indirectly using models that relate lithium concentration with concentrations of other elements that are predicted to be associated with lithium.

In some embodiments, a method includes emitting, from a transmitter positioned in a wellbore formed in a subsurface formation, a pulse of neutrons into the subsurface formation and detecting gamma ray emissions at a near field and a far field generated in response to the pulse of neutrons being emitted into the subsurface formation. The method includes determining a single elemental decay for one chemical element of a number of chemical elements present in the subsurface formation based on the gamma ray emissions and determining at least one geophysical property of the subsurface formation based on the single elemental decay of the one chemical element.

A method includes receiving well log data for a plurality of wells. A flag is generated based at least partially on the well log data. The wells are sorted into groups based at least partially on the well log data, the flag, or both. A model is built for each of the wells based at least partially on the well log data, the flag, and the groups.

A method includes receiving well log data for a plurality of wells. A flag is generated based at least partially on the well log data. The wells are sorted into groups based at least partially on the well log data, the flag, or both. A model is built for each of the wells based at least partially on the well log data, the flag, and the groups.

Component weight and/or volume fractions of subterranean rock are determined. A formation model generates mineral and fluid concentration data from which elemental concentrations are calculated. Forward modeling produces a simulated energy spectrum, and simulation produces a simulated constraining log. Spectra is generated by detecting gamma radiation with a neutron logging tool, and a constraining log is generated. The spectrum and the simulated energy spectrum are compared with resultant error determined. The constraining log and simulated constraining log are compared with resultant error determined. The formation model generates further mineral and fluid concentration to calculate further elemental concentrations. Forward modeling produces further simulated energy spectrum signal and further constraining logs. The spectrum signals and further simulated spectrum signal are compared with resultant error determined. The constraining log and further simulated constraining log are compared, and resultant error is determined. The mineral and fluid concentration are selected that result in minimal error.

A method for measuring an oil saturation value of a subterrain formation uses a tool having multiple dual-function detectors that detect neutrons and gamma rays. The method includes 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 C/O ratios at each of the detectors, a total neutron count rate at each of detectors, a fast neutron count rate at each of detectors, and a thermal neutron count rate at each of the three or more detector, and calculating the oil saturation value using the determined parameters.

A borehole neutron imaging tool having a two-dimensional array of neutron detector crystals, wherein said tool includes at least a source of neutrons; at least one collimated imaging detector to record images created by incident neutrons; sonde-dependent electronics; and a plurality of tool logic electronics and power supply units. A method for borehole neutron imaging, the method including controlling the direction of incident neutrons onto the imaging array; imaging said borehole surroundings; and creating a composite image of the materials surrounding the formation.