Abstract: 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.

Abstract: A wick liquid sensor suitable for use in a particle condensation device is provided. The sensor includes a light source configured to illuminate a surface of the wick. A detector is configured to detect wick reflected light from the light source and determine the intensity of reflected light. The wick is formed from a porous media that is wettable by the liquid, and becomes translucent when filled with the liquid. The amount of reflectivity decreases as the saturation content of the liquid in the wick increases.

Abstract: The present disclosure includes a core sample analysis system that includes a portable sampling device configured to be positioned adjacent to a subsurface core sample. The portable sampling device includes a first module that includes a radiation source. Also, the portable sampling device includes a second module that includes a detector that is configured to detect radiation emitted from the radiation source that reflects off of the subsurface core sample.

Abstract: Examples of techniques for generating a high-resolution lithology model for subsurface formation evaluation are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method includes determining, by a processing device, a low-resolution lithology volumetric model. The method further includes comparing, by the processing device, the low-resolution lithology volumetric model to a high-resolution imaging log. The method further includes calculating, by the processing device, a dynamic boundary curve for each of a plurality of moving windows. The method further includes generating, by the processing device, the high-resolution lithology model based at least in part on the calculated dynamic boundary curve for each of the plurality of moving windows. The method further includes controlling a drilling operation based at least in part on the high-resolution lithology model.

Abstract: A wellbore inspection device includes a radiation generation source operable to emit neutrons, and a radiation detector fixed relative to the radiation generation source and operable to detect backscattered neutron radiation from a surrounding environment. The radiation detector includes a plurality of individually addressable detector elements arranged in one or more concentric rings. Respective amounts of backscattered neutron radiation detected by the individually addressable detector elements within a ring is indicative of the azimuthal direction of the detected backscattered neutron radiation, and the respective amount of backscattered neutron radiation detected by the individually addressable detector elements of two or more concentric rings is indicative of an energy level of the backscattered neutron radiation.

Abstract: The present disclosure provides for a ranging and proximity detection system that includes a radiation source, the radiation source positioned within a first wellbore and a radiation detector positioned within a second wellbore.

Abstract: A boron coated straw detector for use in a neutron detection system is disclosed comprising a boron coated straw having at least one boron-coated septum radially oriented and extending a pre-determined distance towards the center of the straw. Preferably, the straw comprises a plurality of septa comprising a rigid surface, coated on both sides with a boron composition. Preferably, the septa run the length of the straw detector from one end of the straw to the other. The area coated on the septa adds to the area coated on the arc segments offering a significant benefit in sensitivity of the neutron detector.

Abstract: A method for determining azimuthal formation information using neutron activation, wherein the formation is activated by a neutron source and the activation signal is measured by at least one detector trailing the neutron source during the logging operation. The number of detected gamma rays as a function of the detector azimuth may be used to provide azimuthal information for determining an image of the formation surrounding the borehole.

Abstract: A method of processing a signal includes taking a signal recorded by a plurality of signal recorders, applying at least one super-resolution technique to the signal to produce an oscillator peak representation of the signal comprising a plurality of frequency components for a plurality of oscillator peaks, computing at least one Cross Channel Complex Spectral Phase Evolution (XCSPE) attribute for the signal to produce a measure of a spatial evolution of the plurality of oscillator peaks between the signal, identifying a known predicted XCSPE curve (PXC) trace corresponding to the frequency components and at least one XCSPE attribute of the plurality of oscillator peaks and utilizing the identified PXC trace to determine a spatial attribute corresponding to an origin of the signal.

Abstract: A method is disclosed for determining a measured quantity, correlated with an extinction, in a medium, including the steps: radiation of light into the medium and measurement of the extinction after a first path length; radiation of light into the medium and measurement of the extinction after a second path length, wherein the first path length differs from the second path length; and determination of the measured quantity correlated with the extinction using the extinction after first path length and extinction after second path length. Additionally disclosed is a sensor arrangement for execution of the method.

Abstract: A system and method to determine a characteristic of a wellbore based on count rates of scattered photons. The system and method can include determining at least one characteristic of a material surrounding a wellbore by, emitting photons from a photon source at a location in the wellbore, detecting, via one or more detectors, photons scattered by the material, counting the scattered photons based on an energy level, producing count rates of the detected photons for various energy ranges, and calculating a value of the characteristic based on the count rates. The material can be at least one of mud, mud cake, and earth formation.

Abstract: Methods, systems, and computer program products for correcting cased hole neutron porosity logs provide a “residual” correction that substantially accounts for potential coupling between casing thickness and other environmental parameters. The residual correction may be used to derive a casing thickness response function that is customized for the particular well under consideration. The customized casing thickness response function may then be used to adjust cased hole neutron porosity logs for the well in a manner that more accurately accounts for potential coupling of the effects of casing thickness and other environmental parameters, in contrast to existing solutions that tend to ignore such potential coupling.

Abstract: A method to drill a borehole or wellbore through an earthen formation using a drill bit on a drillstring, comprising the steps of: selecting a frequency-domain dynamic model of a drilling assembly that describes the dynamic response of the drilling assembly to excitation at an excitation frequency for operating at a set of selected drilling parameters that include at least rotary speed and weight on bit; calculating a composite vibration index by combining calculated vibration indices for each excitation frequency with the spectral weighting factors for each of the drilling parameter partitions; displaying said composite vibration index for each of the drilling parameter partitions; selecting preferred drilling parameters based on the displayed results, and using the preferred drilling parameters to drill a borehole with the modeled drilling assembly.

Abstract: A boron coated straw detector for use in a neutron detection system is disclosed comprising a boron coated straw having at least one boron-coated septum radially oriented and extending a pre-determined distance towards the center of the straw. Preferably, the straw comprises a plurality of septa comprising a rigid surface, coated on both sides with a boron composition. Preferably, the septa run the length of the straw detector from one end of the straw to the other. The area coated on the septa adds to the area coated on the arc segments offering a significant benefit in sensitivity of the neutron detector.

Abstract: Provided are embodiments of systems, computer medium and computer-implemented methods for logging using a customizable logging tool. In some embodiments, the logging tool is capable of being disposed in a borehole formed in a geologic formation. The logging tool includes a source for emitting signals into the geologic formation surrounding the borehole and a plurality of detectors for detecting signals generated as a result of emission of signals by the source into the geologic formation surrounding the borehole. The plurality of detectors are independently repositionable such that a source-to-detector spacing for the detectors is independently variable, to provide optimum signal depending on the characteristics of the target reservoir, the borehole, and the tool source and detectors.

Abstract: A first radiance meter that is provided so as to face an object in an atmosphere in which there is dust and measures the radiance of the object and a second radiance meter that is provided so as not to oppose the object and measures the radiance of the dust between the object and the first radiance meter are used to measure the temperature of the object on the basis of the object radiance that has been measured by the first radiance meter and the radiance of the dust between the object and the first radiance meter that has been measured by the second radiance meter.

Abstract: A first radiance meter that is provided so as to face an object in an atmosphere in which there is dust and measures the radiance of the object and a second radiance meter that is provided so as not to oppose the object and measures the radiance of the dust between the object and the first radiance meter are used to measure the temperature of the object on the basis of the object radiance that has been measured by the first radiance meter and the radiance of the dust between the object and the first radiance meter that has been measured by the second radiance meter.

Abstract: A method for estimating a drilling fluid flow rate in a subterranean wellbore includes processing an acquired gamma ray spectrum in combination with standard elemental spectra and at least one standard oxygen activation spectrum to compute an oxygen activation yield. The oxygen activation yield is further processed to estimate a drilling fluid flow rate and or to infer a borehole diameter change or a lost circulation event. The gamma ray spectrum is acquired using a logging string employing a neutron source and a natural gamma ray sensor.

Abstract: A radiation detector is provided. The radiation detector includes an outer casing, at least one first detector disposed within said outer casing, the at least one first detector configured to primarily detect gamma ray radiation, at least one second detector disposed within the outer casing, the at least one second detector configured to primarily detect neutron radiation, and a computing device disposed within the outer casing and communicatively coupled to the at least one first detector and the at least one second detector. The computing device is configured to receive first data from the at least one first detector, receive second data from the at least one second detector, determine a number of neutrons and gamma rays detected based on the first and second data, and determine a detected energy spectrum based on the first and second data.

Abstract: The present disclosure describes a downhole tool that includes an electrically operated radiation generator that selectively outputs radiation to a surrounding environment based at least in part on supply of electrical power; a radiation detector that determines a first radiation metric based at least in part on first radiation measured when the electrically operated radiation generator is outputting radiation and that determines a second radiation metric based at least in part on second radiation measured when the electrically operated radiation generator is not outputting radiation; and a control system that determines whether the surrounding environment is properly shielded based at least in part on a relationship between the first radiation metric and the second radiation metric.

Abstract: A calibration site for a gamma-gamma well logging tool for use in mineral exploration, the calibration site having a column consisting of a plurality of blocks of known densities; and a borehole through the column configured to accept the gamma-gamma well logging tool. Further, a method for calibrating a gamma-gamma well logging tool at the calibration site, the method including lowering the gamma-gamma well logging tool into a column consisting of a plurality of blocks of different known densities and having a borehole therein to receive the gamma-gamma well logging tool; raising the gamma-gamma well logging tool at a set rate; capturing a radiation count at a sensor of the gamma-gamma well logging tool; converting the radiation count to a recorded density for a particular depth at a computing device; and comparing the recorded density at each position of the column with the known densities.

Abstract: A radiation detection apparatus can include a scintillator, a photosensor optically coupled to the scintillator, and a control module electrically coupled to the photosensor. The control module can be configured to receive a pulse from the photosensor and identify a cause of noise corresponding to the pulse. Such information can be useful in determining failure modes and potentially predict future failures of radiation detection apparatuses. In another embodiment, the wavelet discrimination can be used to determine whether or not the pulse corresponds to a scintillation pulse, and potentially to identify a type of radiation or a radiation source. The technique is robust to work over a variety of temperatures, and particularly, at temperatures significantly higher than room temperature.

Abstract: An improved MWD system for drilling unconventional wells. Embodiments provide a particular combination of sensors in a specific arrangement in order to provide a system expressly designed for drilling unconventional wells. By minimizing modularity to reduce the need for redundant/duplicated components, including only sensors specifically needed for unconventional wells, and by separating long-life components such as sensors from components requiring more frequent maintenance or service such as batteries, the components can be more efficiently combined into a BHA sensor assembly having the shortest possible length.

Abstract: A downhole tool and method for determining properties of a formation. The method comprising irradiating the formation with a nuclear source; performing both a resistivity and a sigma measurement at each of different radial depths into the formation with a plurality of detectors; and inputting the measurements into a predetermined model for determining the properties of the formation.

Abstract: A well-logging device may include a housing to be positioned within a larger borehole of a subterranean formation and thereby define a stand-off distance with respect to the larger borehole. The well-logging device may also include at least one radiation source carried by the housing to direct radiation into the subterranean formation, and radiation detectors carried by the housing in azimuthally spaced relation to detect radiation from the subterranean formation. The well-logging device may further include a controller to cooperate with the radiation detectors to determine at least one property of the subterranean formation corrected for the stand-off distance.

Abstract: The present invention is a method and apparatus for operating boron-coated straw detectors in sealed mode, without the need for a continuous flow of gas. Sealed-mode operation is necessary when using the boron-coated straw detectors in the field, where access to a continuous flow of the required gas mixture is not practical. Also, sealed-mode operation is necessary when the straw detectors are used as portable instruments, that must be moved from one location to the next swiftly, or that must be operated while in motion.

Abstract: Systems, methods and devices for evaluating an earth formation intersected by a borehole. The method includes using a first radiation responsive component to detect gamma rays having an energy below a threshold energy; using a second radiation responsive component configured to detect gamma rays that traverse the first radiation responsive component; generating a reduced-Compton gamma ray spectrum by generating an anticoincidence gamma ray spectrum indicative of the gamma rays detected by the first radiation responsive component and the gamma rays detected by the second radiation responsive component. The anticoincidence gamma ray spectrum represents those gamma rays of the gamma rays detected by the second radiation responsive component that are not detected in coincidence with the gamma rays detected by the first radiation responsive component.

Abstract: Systems, methods, and devices for determining a porosity of a subterranean formation corrected for borehole effects are provided. One such device may be a downhole tool capable of being lowered into a borehole of a subterranean formation that may include a neutron source, two or more neutron detectors, and data processing circuitry. The neutron source may emit neutrons into the subterranean formation. The two or more neutron detectors may be respectively disposed at two or more azimuthal orientations within the downhole tool, and may detect neutrons scattered by the subterranean formation or borehole fluid in the borehole, or both. Based on the neutrons detected by the neutron detectors, the data processing circuitry may determine a porosity of the subterranean formation corrected for borehole effects.

Abstract: A well-logging tool may be positioned within a borehole of a subterranean formation. The well-logging tool may include a housing having an interior defining a dual-detector receiving chamber extending longitudinally, and having first and second portions, and a first azimuthal radiation detector carried by the first portion of the dual-detector receiving chamber. The first azimuthal radiation detector may include a first gamma-ray detector and a first photodetector associated with the first gamma-ray detector. The well-logging tool may include a second spectral radiation detector carried by the second portion of the dual-detector receiving chamber. The second spectral radiation detector may include a second gamma-ray detector and a second photodetector associated with the second gamma-ray detector.

Abstract: Cross-well electromagnetic (EM) imaging is performed using high-power pulsed magnetic field sources, time-domain signal acquisition, low-noise magnetic field sensors, spatial oversampling and super-resolution image enhancement and injected contrast fluids. The contrast fluids increase the electromagnetic character of the formation and fluids, either the magnetic permeability or the dielectric permittivity. The acquired signals are processed and inter-well images are generated mapping electromagnetic (EM) signal speed (group velocity) rather than conductivity maps. EM velocity maps with improved resolution for both native and injected fluids are provided.

Abstract: An apparatus for estimating at least one property of an earth formation is disclosed. The apparatus includes: a carrier configured to be disposed in the formation; a neutron tube disposed at the carrier and located on an axis; a high voltage power source disposed in the carrier and electrically connected to the neutron tube, the high voltage power source located remotely from the neutron tube; and at least one detector disposed in the carrier and located proximate to the neutron tube.

Abstract: A well-logging tool may be positioned within a borehole of a subterranean formation. The well-logging tool may include a housing having an interior defining a dual-detector receiving chamber extending longitudinally, and having first and second portions, and a first azimuthal radiation detector carried by the first portion of the dual-detector receiving chamber. The first azimuthal radiation detector may include a first gamma-ray detector and a first photodetector associated with the first gamma-ray detector. The well-logging tool may include a second azimuthal radiation detector carried by the second portion of the dual-detector receiving chamber. The second azimuthal radiation detector may include a second gamma-ray detector and a second photodetector associated with the second gamma-ray detector.

Abstract: A well-logging tool may be positioned within a borehole of a subterranean formation. The well-logging tool may include a housing having an interior defining a dual-detector receiving chamber extending longitudinally, and having first and second portions, and a first azimuthal radiation detector carried by the first portion of the dual-detector receiving chamber. The first azimuthal radiation detector may include a first gamma-ray detector and a first photodetector associated with the first gamma-ray detector. The well-logging tool may include a second spectral radiation detector carried by the second portion of the dual-detector receiving chamber. The second spectral radiation detector may include a second gamma-ray detector and a second photodetector associated with the second gamma-ray detector.

Abstract: Techniques and apparatus are provided for downhole sensing using optical couplers in a downhole splitter assembly to split interrogating light signals into multiple optical sensing branches. Each optical branch may then be coupled to an optical sensor (e.g., a pass-through or an optical single-ended transducer (OSET)) or to another optical coupler for additional branching. The sensors may be pressure/temperature (P/T) type transducers. Some systems may exclusively use OSETs as the optical sensors. In this manner, if one of the OSETs is damaged, it does not affect light traveling to any of the other sensors, and sensing information from remaining sensors is still returned.

Abstract: Various embodiments include apparatus and methods to operate a tool downhole in a well, where the tool has an optical computation element to determine different properties of downhole structures. Such an optical computation element can be structured to provide optical analysis of fluid and material composition of the downhole environment associated with a drilling operation. The data measurements from the optical computation element can be used in a geosteering operation. Additional apparatus, systems, and methods are disclosed.

Abstract: An apparatus and method for estimating at least one parameter of interest of an earth formation including an estimation of the parameter of interest using a time-dependent ratio of information obtained from at least one neutron detector through the exposure of the earth formation to a radiation source, particularly a pulsed nuclear source. The apparatus includes a processor and storage subsystem with a program that, when executed, implements the method. Also, an apparatus and method for estimating at least one parameter of interest of an earth formation including an estimation of the parameter of interest using a first component and a second component of an information set obtained using a single radiation detector.

Abstract: Cross-well electromagnetic (EM) imaging is performed using high-power pulsed magnetic field sources, time-domain signal acquisition, low-noise magnetic field sensors, spatial oversampling and super-resolution image enhancement and injected magnetic nanofluids. The acquired signals are processed and inter-well images are generated mapping electromagnetic (EM) signal speed (group velocity) rather than conductivity maps. EM velocity maps with improved resolution for both native and injected fluids are provided.

Abstract: A disclosed subsurface electromagnetic field monitoring system includes at least one fiberoptic cable to optically communicate measurements from an array of electromagnetic field sensors in a borehole.

Abstract: A downhole gamma ray density measurement system is described. The gamma ray density measurement system includes a pressure housing and a gamma ray source within the pressure housing. One or more detectors within the pressure housing detect gamma radiation. One or more low-attenuation inserts may be located in the pressure housing near the gamma ray source and/or one or more of the detectors. One or more high-attenuation inserts may be located in the pressure housing near the gamma ray source and/or one or more of the detectors.

Abstract: A disclosed formation monitoring system includes a casing that defines an annular space within a borehole. An array of electromagnetic field sensors is positioned in the annular space and configured to communicate with the surface via a fiberoptic cable. A computer coupled to the fiberoptic cable receives said measurements and responsively derives the location of any fluid fronts in the vicinity such as a an approaching flood front to enable corrective action before breakthrough. A disclosed formation monitoring method includes: injecting a first fluid into a reservoir formation; producing a second fluid from the reservoir formation via a casing in a borehole; collecting electromagnetic field measurements with an array of fiberoptic sensors in an annular space between said casing and said borehole, said array communicating measurements to a surface interface via one or more fiberoptic cables; and operating on said measurements to locate a front between the first and second fluids.

Abstract: Various systems and methods for implementing a directional radiation detection tool are disclosed. One such method involves receiving outputs from several radiation sensors (e.g., gamma ray sensors), which are each facing a different direction. The received outputs are then combined, such that a directional error in one of the outputs is reduced, based upon another one of the outputs.

Abstract: This invention relates to nondestructive control, more specifically, to the detection of cracks, flaws and other defects in oil and gas wells and cementing quality control.

Abstract: An apparatus for detecting thermal and epithermal neutrons. The apparatus includes a first radiation responsive element configured to absorb substantially all incident thermal neutrons and produce first light scintillations indicative of the absorbed thermal neutrons and a second radiation responsive element configured to produce second light scintillations indicative of at least epithermal neutrons that traverse the first radiation responsive element. Also disclosed are borehole logging methods and apparatuses for estimating formation properties using nuclear radiation, particularly an apparatus and method for estimating parameters of a formation. The method may include using neutron count rate information from a detector to model porosity or salinity. The apparatus includes a processor and storage subsystem with a program that, when executed, implements the method.

Abstract: Cross-well electromagnetic (EM) imaging is performed using high-power pulsed magnetic field sources, time-domain signal acquisition, low-noise magnetic field sensors, spatial oversampling and super-resolution image enhancement and injected magnetic nanofluids. Inter-well images are generated mapping electromagnetic (EM) signal speed (group velocity) rather than conductivity maps. EM velocity maps with improved resolution for both native and injected fluids are provided.

Abstract: The present disclosure relates to determining the attenuation of an electromagnetic signal passing through a conductive material. An antenna is provided and placed in relatively close proximity to the conductive material. An alternating current is passed through the antenna and the impedance of the antenna is measured. The attenuation is determined using the measured impedance. A single frequency measurement may be made, or multiple measurements using different frequencies may be made. Grouped parameters based on properties of the material and the frequency of the current are used to relate the coil impedance to the attenuation. A current frequency for which the ratio of the antenna's resistive part of the impedance to the angular frequency of the current is substantially insensitive to at least one of the parameters is preferred.

Abstract: The present invention provides a method and an apparatus for calibrating a first self-powered neutron detector for long term use in a nuclear reactor core with a second self-powered neutron detector, where the emitter material of the second self-powered neutron detector has a neutron absorption cross-section that is greater than the neutron absorption cross-section of the first emitter material for the first self-powered neutron detector.

Abstract: The present invention provides a device for measuring a mean free path capable of measuring directly the mean free path of a charged particle, a vacuum gauge, and a method for measuring a mean free path. The device for measuring a mean free path according to one embodiment of the invention includes an ion source for generating an ion, a collector (24a) for detecting the number of first charged particles being charged particles having a first flight distance L1 that is a flight distance of zero or more from the ion source, and a collector (24b) for detecting the number of second charged particles having a second flight distance longer than the first flight distance. The control part of the device calculates the mean free path from a ratio between the numbers of the first and second charged particles.

Abstract: A downhole tool with two detectors located at different distances from a neutron source, has at least one dual gamma ray and neutron detector that includes a first detection element made of a neutron detector material, and a second element made of a gamma ray scintillation material, the first detection element and the second detection element being optically connected to a photomultiplier.

Abstract: A neutron logging tool has multiple detectors spaced about the circumference of the tool. The detectors are shielded from each other such that each detector detects gamma rays from the area of the borehole and formation to which it is closest. The log readings from each detector can be associated with the orientation of that detector. The orientation-specific log readings can then be aggregated to form an azimuthal log which can be used to analyze pre-fractured and/or post-fractured formations.

Abstract: The present disclosure relates to borehole logging methods and apparatuses for estimating at least one parameter of interest of a volume of interest of an earth formation using nuclear radiation. The method may include obtaining an energy spectrum; using at least one processor to remove at least one energy spectrum component using a method selected from a spectral decomposition and spectral windows method; and estimating the concentration of at least one radionuclide using the energy spectrum after the removal. The estimation of the at least one radionuclide concentration may include using the other of the method selected form the removal. The apparatus may include at least one processor configured to perform the method.