Abstract: Methods and system are provided for measuring parameters while drilling a wellbore using a coiled tubing drilling apparatus. An exemplary system includes an instrumented mandrel including a notch in an outer surface of the instrumented mandrel, and an indentation at each end of the notch. A sensor package in the system includes a sensor, a tubular assembly, and a mounting bracket at each end of the tubular assembly. The sensor package is sized to fit in the notch, with each of the mounting brackets fitting in one of the indentations at each end of the knot, and wherein the sensor package is substantially flush with the instrumented mandrel.

Abstract: An approach for reservoir characterization is based on rock geochemistry of the subterranean formation. This approach includes: collecting rock samples related to lithostratigraphy of target wells; measuring geochemical/ mineralogical parameters of the rock samples; measuring geochemical/mineralogical parameters of the subsurface formation; measuring formation acoustic velocities for the target wells; generating characteristic rock sample and log signature patterns for different lithostratigraphic layers based on the measured geochemical/mineralogical parameters and acoustic velocities associated with the different lithostratigraphic layers identified in the target wells; combining the characteristic log signatures for the different lithostratigraphic layers into a lithographic interpretation using neutron capture spectroscopy model; and identifying the lithostratigraphic layers within the subterranean formation by applying the model to well logs of non-target wells.

Abstract: 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.

Abstract: A control module for a radiation detector can be configured to use a first pulse shape discrimination technique at a first state, and use a second pulse shape discrimination technique at a second state.

Abstract: Methods of evaluating a parameter of interest of a formation intersected by a borehole, including exposing a radiation sensor in the borehole to a calibration radiation source while a measurement operation using the radiation sensor is suspended. Methods may include exposing the radiation sensor to the calibration radiation source when the radiation sensor is stationary relative to the formation or during interruption of drilling operations or at predetermined intervals; processing response information, including performing a mitigation process on a portion of the response information relating to exposure of the radiation sensor to a calibration radiation source during measurement operations; or using the calibrated measurement information to estimate parameters of interest. Devices may include a radiation sensor, a calibrator including a calibration radiation source, and an actuator configured to intermittently expose the radiation sensor to the calibration radiation source.

Abstract: A method of estimating at least one property of an earth formation includes: constructing a matrix model of a formation; constructing a shale model of the formation, the shale model including an estimation of a concentration of at least one trace element; combining the first model and the second model to generate a formation model; and comparing measured pulsed neutron data with the mixed model to estimate the at least one property.

Abstract: A method is for creating a gamma ray source downhole by creating a radioactive material through irradiation of an inert material by high energy neutrons, wherein the material to be activated may surround the neutron source in close proximity to form a compact gamma ray source. The gamma rays generated by the activation may be used to perform nuclear measurements downhole.

Abstract: Data acquired using a pulsed nuclear source are susceptible to two sources of error. One error is due to large statistical noise towards the end of an acquisition window. Another source of error is the contamination of the early portion of the data by borehole and other effects. The beginning of the processing window is adjusted based on the signal level at the end of the processing window for the preceding pulsing of the source. The end of the processing window is derived from statistical considerations.

Abstract: Apparatus and methods for measuring radiation in a borehole environment using a YAlO3:Ce (YAP) scintillation crystal. Borehole instruments are disclosed which employ a gamma ray detector comprising a YAP scintillator coupled to a light sensing means such as a photomultiplier tube. One instrument embodiment combines a YAP scintillation detector and a source of pulsed neutrons. Borehole environs are irradiated with neutrons, and induced gamma radiation is measured using a YAP scintillation detector. Response of the detector is used to determine characteristics of the borehole environs. Mechanical and physical properties of YAP are utilized to obtain improved measurements. The relatively short light decay constant of YAP minimized pulse pile-up in the detector when measurements require that the detector be operated during a neutron pulse.

Abstract: Apparatus and methods for measuring radiation in a borehole environment using a YAlO3:Ce (YAP) scintillation crystal. Borehole instruments are disclosed which employ a gamma ray detector comprising a YAP scintillator coupled to a light sensing means such as a photomultiplier tube. One instrument embodiment combines a YAP scintillation detector and a source of pulsed neutrons. Borehole environs are irradiated with neutrons, and induced gamma radiation is measured using a YAP scintillation detector. Response of the detector is used to determine characteristics of the borehole environs. Mechanical and physical properties of YAP are utilized to obtain improved measurements. The relatively short light decay constant of YAP minimized pulse pile-up in the detector when measurements require that the detector be operated during a neutron pulse.

Abstract: A system and method for rapidly analyzing elemental abundances in rock or soil samples (14) under field conditions. The system uses a portable neutron source (12) to allow neutron activation analysis of elements having identifiable radioactive decay characteristics. A radiation detector (18) detects radiation released by the sample (14) and provides radiation testing results to an amplifier (26) for computing the concentration of trace elements in the sample with a high degree of accuracy.

Abstract: Apparatus and methods for measuring radiation in a borehole environment using a YAlO3:Ce (YAP) scintillation crystal. Borehole instruments are disclosed which employ a gamma ray detector comprising a YAP scintillator coupled to a light sensing means such as a photomultiplier tube. One instrument embodiment combines a YAP scintillation detector and a source of pulsed neutrons. Borehole environs are irradiated with neutrons, and induced gamma radiation is measured using a YAP scintillation detector. Response of the detector is used to determine characteristics of the borehole environs. Mechanical and physical properties of YAP are utilized to obtain improved measurements. The relatively short light decay constant of YAP minimized pulse pile-up in the detector when measurements require that the detector be operated during a neutron pulse.

Abstract: A method and device for taking non-invasive on-site soil carbon content and distribution measurements at the surface of the soil utilizing a neutron generator positioned on the surface of the soil to generate neutrons that penetrate the soil. The neutrons cause inelastic neutron scattering (INS) from carbon and subsequent emission of gamma rays from the first carbon excited level. The gamma rays are measured by a number of suitable on-site gamma ray detectors situated near the neutron generator. A nuclear spectroscopy system is utilized to generate an energy spectrum of the detected emitted gamma rays and a net number of gamma rays is determined by subtracting a background count from a total count at a predetermined energy level. The net count is then compared to a predetermined calibration plot to determine the weight percentage of carbon within the measured soil.

Abstract: A system for determining depth profiles of concentrations of hazardous elements in soils comprises a neutron source for generating neutrons of a first energy level and irradiating a volume of soil with the neutrons. Nuclear reactions are effected within the soil and gamma radiation is emitted from the soil. The system also includes an array of gamma detectors for detecting gamma radiation emitted from the soil; source electronics for controlling the width of regularly repeated pulses of neutrons generated by the neutron source; detector electronics associated with the gamma detectors for amplifying and digitalizing signals generated by the gamma detectors and storing data representing the digitalized signals; spectral analysis software for analyzing the data and determining the concentrations of selected target elements in the soil; and an acquisition interface module (AIM).

Abstract: Fast neutrons from a moving source are thermalized by travel through water to a soil embedded body of nitrogen-rich material causing emission of gamma rays therefrom. Emitted gamma rays are detected at a location adjacent the neutron source for measurement of radiation energy from which location of nitrogen-rich materials in the soil is mapped, based on a predetermined signature energy level of the measured radiation.

Abstract: A nuclear apparatus for obtaining qualitative and quantitative information related to an element of earth formation surrounding a borehole, comprising: (1) a neutron source for irradiating the formation with neutrons of sufficient energy to activate atoms of at least a given element; (2) at least two (preferably four) detectors longitudinally spaced from said source, for detecting the gamma rays emitted during the activation reaction; (3) means for assigning a maximum number of counts for each detector and for establishing a relationship between these maximum number of counts and the corresponding instant of time counts for each detector; and (4) means for deriving from the relationship qualitative information related to the element.The relationship is approximately a straight line, the slope of which is representative of the element of interest. The amplitude of the counts is representative of the quantity of the activated element and of the radial distance between the activated atoms and the borehole.

Abstract: A method and apparatus for determining true formation porosity utilize downhole measurement-while-drilling neutron porosity measurement devices. A initial measurement is taken shortly after the formation is bored and before any substantial invasion by the drilling fluid occurs. Subsequent measurements are made until a steady, no longer increasing, measurement is reached indicating saturation of the formation by the drilling fluid to the depth of the measurements. The steady measurement is indicative of the true porosity of a gas containing formation while the difference between the initial and steady measurements is indicative of the gas saturation of a gas containing formation.

Abstract: A method for logging a cased well to determine the quantity and location of any barite weighted drilling fluid in the annulus between the casing and the wall of the wellbore. A tool assembly having a neutron generator and a gamma scintillation detector is used to log the zone of interest. The neutrons introduced into the well by the neutron generator convert a portion of the barium-138 in the drilling fluid to barium-137m. The magnitude of the gamma photon peak charactristic of the decayof barium-137 is used to identify the quantity of drilling fluid present in the annulus as a function of depth. This method is especially useful identifying the existence of channels in a cemented wellbore annulus.

Abstract: Capture gamma ray spectroscopy measurements of earth formations traversed by a borehole are corrected for the influence thereon of the geometry and constituents of the borehole, thereby affording more accurate measurements of the spectral contributions from the formation elements. A partition factor is determined for each separate homogeneous region in the borehole/formation measurement environment, i.e., the tool, the borehole fluid, the casing (if present), the cement annulus (if present), and the formation, and these factors are plugged into predetermined elemental yield relationships, for the elements for which capture spectral measurements are made, to determine the volumetric fractions of such elements (or minerals containing such elements) in the formation.