A method for determining a tubing deviation from nuclear measurement data includes acquiring neutron measurement data from a wellbore. The method also includes identifying one or more features from the neutron measurement data. The method further includes determining, based at least in part on a pattern matching algorithm, that the one or more features are indicative of a tubular deviation. The method also includes determining, based at least in part on a comparison between the one or more features, a deviation amount.

Methods and systems for measuring neutron sigma of downhole reservoir as a function of time for a predetermined testing volume are disclosed. The methods and systems of the present invention analyze the testing volume while maintaining the formation in the testing volume in an unchanged and undamaged state and while dynamically flowing fluids in and out of the testing volume. The systems and methods of the present invention are especially important in determining petrophysical information about the reservoir as well as the in-situ effect of substances on enhanced oil recovery.

A combining mechanism for borehole logging tool data that employs modality merging to combine the output data of various borehole logging tools to provide a combined result and automated interpretation is provided, said mechanism comprising: at least one mechanism for assigning interpretive values to individual processed data types; at least one mechanism for combining the interpretive value data sets; and, at least one mechanism for providing an interpretation. A method of combining borehole logging tool data that employs modality merging to combine the output data of various borehole logging tools to provide a combined result and automated interpretation is also provided, said method comprising: assigning interpretive values to individual processed data types; combining the interpretive value data sets; and, providing an interpretation.

A downhole logging tool includes a radiation generation source operable to emit radiation into a formation surrounding the tool, a radiation detector fixed relative to the radiation generation source and operable to detect backscattered radiation from the formation surrounding the tool, and a sleeve positioned around the radiation detector to shield the radiation detector from a first portion of the backscattered radiation. The sleeve includes at least one aperture for exposing the radiation detector to a second portion of the backscattered radiation, in which the second portion of the backscattered radiation emanates from an inspected region of the formation facing the at least one aperture. A signal measured at the radiation detector corresponds to the inspected region of the formation, and the position of the at least one aperture is changeable with respect to the formation to distinctly inspect different regions of the formation.

Embodiments of the present disclosure include a system for detecting neutrons with a housing, a gas chamber at least partially defined by the housing, an anode extending through at least a portion of the gas chamber, and a pseudogas arranged within the gas chamber. The pseudogas comprises a mixture of gas and suspended solid particles that contain an element with a high cross-section for thermal neutron capture.

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.

Methods and tools for determining one or more parameters of an earth formation using time-of-flight (TOF) measurements of fast neutrons through the formation are disclosed. The disclosed tools feature a neutron source capable of emitting a population of fast neutrons having a distribution of neutron energies and one or more neutron detectors. The TOF of the fast neutrons travelling from the neutron source to the detector(s) and traversing a portion of the formation is measured and binned as a function of TOF (which is a function of neutron energy). By determining which neutron energies are attenuated by the intervening formation, the composition of the intervening formation is determined.

A downhole inspection system includes a neutron imaging device operable to generate data for detecting potential wellbore anomalies and an electromagnetic imaging device operable to generate data for detecting potential wellbore eccentricity. The neutron imaging device includes a neutron generator operable to emit neutrons, and a neutron detector fixed relative to the neutron generation unit and operable to detect backscattered neutrons from a surrounding environment. The electromagnetic imaging device includes at least one transmitter for generating electromagnetic pulse, and at least one receiver for detecting returning electromagnetic pulse. Correlation of the neutron imaging data with the electromagnetic imaging data provides additional data regarding the potential wellbore anomalies.

A method for determining a fractional volume of at least one component of a formation includes entering into a computer a number of detected radiation events resulting from imparting neutrons into the formation at an energy level of at least 1 million electron volts (MeV). The detected radiation events correspond to at least one of an energy level of the imparted neutrons and thermal or epithermal energy neutrons. A measurement of at least one additional petrophysical parameter of the formation is made. The at least one additional petrophysical parameter measurement and at least one of a fast neutron cross-section and a thermal neutron cross-section determined from the detected radiation events are used in the computer to determine the fractional volume of the at least one component of the formation. In another embodiment, the fast neutron cross-section and the thermal neutron cross-section may be used on combination to determine the fractional volume.

A method includes introducing a tool string into a wellbore having material disposed in an annular region surrounding the casing. Obtaining acoustic refracted waveform measurements of the material from a cement bond logging tool, obtaining ultrasonic measurements of the material from a circumferential acoustic scanning tool, obtaining gamma radiation measurements scattered from the material from a circumferential spectral density logging (RSDX) tool by emitting gamma radiation from a radioactive source in a rotating portion of the RSDX and detecting scattered gamma radiation using near and far spectral density detectors, and obtaining thermal neutron radiation measurements scattered from the material from a dual spaced neutron logging tool. A computer obtains measurements and generates a deliverable that includes one or more cross plots that identify a compositional equivalent of the material in an entire circumference of the wellbore.