Patent application number | Description | Published |
20090045329 | Downhole Tools Having Combined D-D and D-T Neutron Generators - A nuclear tool includes a tool housing; a d-D neutron generator disposed in the tool housing; a d-T neutron generator disposed in the tool housing; and, optionally, a control circuit for controlling pulsing of the d-D neutron generator and the d-T neutron generator. A method for well-logging using a nuclear tool includes disposing the nuclear tool in a wellbore penetrating a formation; pulsing a d-D neutron generator to emit neutrons at a first energy level into the formation; pulsing a d-T neutron generator to emit neutrons at a second energy level into the formation; and measuring signals returning from the formation. | 02-19-2009 |
20090057545 | Downhole Tools with Solid-State Neutron Monitors - A nuclear tool includes a tool housing; a neutron generator disposed in the tool housing; and a solid-state neutron monitor disposed proximate the neutron generator for monitoring the output of the neutron generator. A method for constructing a nuclear tool includes disposing a neutron generator in a tool housing; and disposing a solid-state neutron monitor proximate the neutron generator for monitoring the output of the neutron generator. A method for logging a formation includes disposing a nuclear tool in a wellbore penetrating the formation, wherein the nuclear tool comprises a neutron generator and a solid-state neutron monitor disposed proximate the neutron generator; generating neutrons from the neutron generator; monitoring neutrons generated by the neutron generator using the solid-state neutron monitor; detecting signals generated from the neutrons traveling in the formation; and correcting the detected signals, based on signal strength detected by the solid-state neutron monitor, to produce corrected signals. | 03-05-2009 |
20090139713 | METHOD AND APPARATUS FOR DETECTING WHILE DRILLING UNDERBALANCED THE PRESENCE AND DEPTH OF WATER PRODUCED FROM THE FORMATION - The invention relates to methods and apparatus for determining a downhole parameter in an underbalanced drilling environment which include: selectively activating a first fluid flowing from the formation through a wellbore while under balanced drilled; detecting the activated first fluid, and determining a depth at which said fluid enters the wellbore. | 06-04-2009 |
20090140134 | Hermetically Sealed Packaging and Neutron Shielding for Scintillation-Type Radiation Detectors - A well logging instrument includes a source of high energy neutrons arranged to bombard a formation surrounding the instrument. A scintillator sensitive to gamma radiation resulting from interaction of the high energy neutrons with the formation is disposed in the instrument. A neutron shielding material surrounds the scintillator. A neutron moderator surrounds the neutron shielding material. An amplifier is optically coupled to the scintillator. | 06-04-2009 |
20090150077 | Pulsed X-Ray Signal Processing - Method and system for analyzing electrical pulses contained in a pulse train signal representative of the interaction of x-ray bursts with a nuclear detector configured for subsurface disposal. The pulse train signal is sampled to form a digitized signal. The total energy deposited at the detector during an x-ray burst is determined from the digitized signal, and a count rate of x-ray pulses from the burst is determined. A subsurface parameter is determined using the total energy deposit. | 06-11-2009 |
20090153011 | INJECTOR FOR BETATRON - An electron acceleration portion of a Betatron having a vacuum chamber with an interior wall spaced from an exterior wall with a main electron orbit located approximate to the exterior wall and the interior wall. An electron injector has an anode structured and arranged adjacent a wall selected from the group consisting of the interior wall and the exterior wall that is shaped so as to not impede the main electron orbit. There is at least one electron deflection plate disposed approximate an anode end of the anode and the main electron orbit. There can be two electron deflection plates spaced apart that form a gap of a width effective to receive emitted electrons from the electron injector. Such that, there is a voltage potential between the two electron deflection plates that is effective to deflect emitted electrons towards the main electron orbit. | 06-18-2009 |
20090153079 | BETATRON BI-DIRECTIONAL ELECTRON INJECTOR - A Betatron having a toroidal passageway disposed in a cyclical magnetic field with a main electron orbit circumnavigating the toroidal passageway. Within the toroidal passageway is a first electrode that is spaced apart from a second electrode. The combination of the first electrode and the second electrode define a central space having a first opening and a second opening. A cathode is disposed within the central space. This cathode has a first electron emitter aligned to inject electrons through the first opening and a second electron emitter aligned to inject electrons through the second opening. Electrons injected in a proper direction are accelerated in the main electron orbit. At a time of maximum electron acceleration, the electrons are deflected and impact a target that generates x-rays on impact. | 06-18-2009 |
20090274276 | HIGH VOLTAGE X-RAY GENERATOR AND RELATED OIL WELL FORMATION ANALYSIS - An apparatus and method for determining the density and other properties of a formation surrounding a borehole using a high voltage x-ray generator. One embodiment comprises a stable compact x-ray generator capable of providing radiation with energy of 250 keV and higher while operating at temperatures equal to or greater than 125° C. In another embodiment, radiation is passed from an x-ray generator into the formation; reflected radiation is detected by a short spaced radiation detector and a long spaced radiation detector. The output of these detectors is then used to determine the density of the formation. In one embodiment, a reference radiation detector monitors a filtered radiation signal. The output of this detector is used to control at least one of the acceleration voltage and beam current of the x-ray generator. | 11-05-2009 |
20090283691 | NEUTRON SHIELDING FOR DOWNHOLE TOOL - A downhole tool for performing measurement of a formation. The tool comprising a housing surrounding a source for generating neutrons and a detector for detecting the neutrons. A shield is located outside of, or embedded in, the housing and focuses the neutrons. | 11-19-2009 |
20090321622 | DETERMINING DOWNHOLE FLUID FLOW - Apparatus for determining properties of a borehole and a formation around the borehole. The apparatus comprising a source for generating nuclear particles, a detector for measuring a effect of the nuclear particles on a fluid flowing in the borehole and a second detector for measuring an effect of the nuclear particles on the formation. The source is arranged to generate the nuclear particles in a manner that enables the measuring of the first and the second detector to be performed simultaneously. | 12-31-2009 |
20100090111 | THERMALLY-PROTECTED SCINTILLATION DETECTOR - Systems, methods, and devices for thermally protecting a scintillator crystal of a scintillation detector are provided. In one example, a thermally-protected scintillator may include a scintillator crystal and a thermal protection element, which may partially surround the scintillator crystal. The thermal protection element may be configured to prevent the scintillator crystal from experiencing a rate of change in temperature sufficient to cause cracking or non-uniform light output, or a combination thereof. | 04-15-2010 |
20100116978 | GAIN STABILIZATION OF GAMMA-RAY SCINTILLATION DETECTOR - Systems and methods for stabilizing the gain of a gamma-ray spectroscopy system are provided. In accordance with one embodiment, a method of stabilizing the gain of a gamma-ray spectroscopy system may include generating light corresponding to gamma-rays detected from a geological formation using a scintillator having a natural radioactivity, generating an electrical signal corresponding to the light, and stabilizing the gain of the electrical signal based on the natural radioactivity of the scintillator. The scintillator may contain, for example, naturally radioactive elements such as Lutetium or Lanthanum. | 05-13-2010 |
20100187412 | SIGMA MEASUREMENT DOWNHOLE - A downhole tool and method for performing a base log sigma measurement of a formation. The tool comprising a nuclear source for irradiating the formation and a detector for obtaining a sigma measurement of the irradiated formation. The tool is mounted close to a drill bit arranged to drill a borehole into the formation and is capable of determining a base log sigma measurement of the formation while drilling into the formation. | 07-29-2010 |
20100193675 | NEUTRON SHIELDING FOR DOWNHOLE TOOL - A downhole tool for performing measurement of a formation. The tool comprising a housing surrounding a source for generating neutrons and a detector for detecting the neutrons. A shield is located outside of, or embedded in, the housing and focuses the neutrons. | 08-05-2010 |
20100243877 | SCINTILLATOR BASED RADIATION DETECTION - Methods and related systems are described for the detection of nuclear radiation. The system can include a tool body adapted to be deployed in a wellbore and a scintillator material that intrinsically generates radiation. The scintillator material is mounted within the tool body. A photodetection system is coupled to the scintillator material, and mounted within the tool body. Features in a spectrum associated with a scintillation material's intrinsic radioactive decay are used for the determination of one or more parameter's of the response function of the radiation detector system. | 09-30-2010 |
20100282971 | Method and Apparatus for Radiation Detection in a High Temperature Environment - A radiation detector operating at high temperatures is shown comprising a scintillating material for producing light when excited by incident radiation, a photocathode, and an electron multiplier. The photocathode is deposited directly onto the surface of the scintillating material that is oriented toward the electron multiplier. Depositing the photocathode directly on the surface greatly decreases photon loss which is a problem of prior art systems. In a preferred embodiment, a metal flange is hermetically sealed to the scintillating material and this is fusion welded to the electron multiplier to create a vacuum envelope. This invention is particularly useful in noisy environments such as downhole in a drilling operatio | 11-11-2010 |
20110002443 | High Voltage X-Ray Generator and Related Oil Well Formation Analysis Apparatus and Method - An apparatus and method for determining the density and other properties of a formation surrounding a borehole using a high voltage x-ray generator. One embodiment comprises a stable compact x-ray generator capable of providing radiation with energy of 250 keV and higher while operating at temperatures equal to or greater than 125° C. In another embodiment, radiation is passed from an x-ray generator into the formation; reflected radiation is detected by a short spaced radiation detector and a long spaced radiation detector. The output of these detectors is then used to determine the density of the formation. In one embodiment, a reference radiation detector monitors a filtered radiation signal. The output of this detector is used to control at least one of the acceleration voltage and beam current of the x-ray generator. | 01-06-2011 |
20110012015 | Apparatus and Methods for Measuring Formation Characteristics - An apparatus can measure characteristics of a formation surrounding a borehole. The apparatus comprises a tool body including a neutron measurement section including a neutron source and a neutron detector arrangement spaced in an axial direction from the neutron source; and | 01-20-2011 |
20110114830 | ELECTRODE CONFIGURATION FOR DOWNHOLE NUCLEAR RADIATION GENERATOR - Systems, methods, and devices with improved electrode configuration for downhole nuclear radiation generators are provided. For example, one embodiment of a nuclear radiation generator capable of downhole operation may include a charged particle source, a target material, and an acceleration column between the charged particle source and the target material. The acceleration column may include several electrodes shaped such that substantially no electrode material from the electrodes is sputtered onto an insulator surface of the acceleration column during normal downhole operation. | 05-19-2011 |
20110272570 | Method and Apparatus for Neutron Logging Using a Position Sensitive Neutron Detector - A neutron logging tool includes a neutron source and at least one position sensitive thermal or epithermal neutron detector. The logging tool further includes an electronic controller configured to estimate the axial location of detected neutrons. Measurement of the axial neutron flux distribution enables other formation and borehole parameters such as formation porosity and sensor standoff to be computed. In logging while drilling embodiments, a borehole caliper may also be computed form the axial neutron flux distribution. | 11-10-2011 |
20120119076 | Method and Apparatus for Detecting while Drilling Underbalanced The Presence and Depth of Water Produced from The Formation and for Measuring Parameters Related Thereto - The invention relates to methods and apparatus for determining a downhole parameter in an underbalanced drilling environment which include: selectively activating a first fluid flowing from the formation through a wellbore while under balanced drilled; detecting the activated first fluid, and determining a depth at which said fluid enters the wellbore. | 05-17-2012 |
20120126105 | NON-ROTATING LOGGING-WHILE-DRILLING NEUTRON IMAGING TOOL - A method and apparatus for obtaining neutron images of a rock formation are provided. The neutron images can be obtained from a tool in a logging-while-drilling system but which need not rotate to obtain neutron data from a plurality of azimuthal orientations. | 05-24-2012 |
20120126106 | Neutron Detection Using a Shielded Gamma Detector - A tool having a neutron source, a gamma ray detector, and a photomultiplier tube is provided. The gamma ray detector and the photomultiplier tube are at least partially surrounded by a layer of boron. The tool is used to make measurements, and the number of prompt gamma rays emitted by the boron is determined from the measurements. The number of neutrons detected may be inferred using the determined number of prompt gamma rays. The tool may also have a layer of neutron absorbing material different from boron or a layer of heavy metal at least partially surrounding the boron. The tool may be a logging tool used to delineate a porous formation and to determine its porosity. The tool may have a plurality of gamma ray detector/photomultiplier tube pairs and those pairs may be used to determine a formation hydrogen index and/or a borehole hydrogen index. | 05-24-2012 |
20120138782 | Logging-While-Drilling Tool Incorporating Electronic Radiation Generator and Method for Using Same - Logging-while-drilling tools incorporating an electronic radiation generator, such as an electronic X-ray generator, and a method for using the same are provided. One example of such a logging-while-drilling tool may include a circumferential drill collar, a chassis disposed radially interior to the drill collar, and an electronic X-ray generator and an X-ray detector disposed within the chassis. The electronic X-ray generator may emit X-rays out of the logging-while-drilling tool into a subterranean formation. The X-ray detector may detect X-rays that return to the logging-while-drilling tool after scattering in the subterranean formation, which may be used to determine a density and/or a lithology of the subterranean formation. | 06-07-2012 |
20120186061 | Scintillator Crystal Materials, Scintillators And Radiation Detectors - The present disclosure describes a scintillation crystal having the general formula RE(1−y)M | 07-26-2012 |
20120197529 | Optimization Of Neutron-Gamma Tools For Inelastic-Gamma Ray Logging - Systems, methods, and devices for inelastic gamma-ray logging are provided. In one embodiment, such a method includes emitting neutrons into a subterranean formation from a downhole tool to produce inelastic gamma-rays, detecting a portion of the inelastic gamma-rays that scatter back to the downhole tool to obtain an inelastic gamma-ray signal, and determining a property of the subterranean formation based at least in part on the inelastic gamma-ray signal. The inelastic gamma-ray signal may be substantially free of epithermal and thermal neutron capture background. | 08-02-2012 |
20120228472 | High Strength Optical Window For Radiation Detectors - The invention provides a hermetically sealed scintillation crystal package with a window made of a ruggedized material such as ALON (aluminum Oxynitride) or Spinel ceramic (MgAl | 09-13-2012 |
20120235030 | Test Formation Apparatus for a Downhole Tool - An insert apparatus for use in a test formation for a downhole nuclear spectroscopy tool includes an outer liner, and an inner liner defining a cylindrical borehole having a diameter such that the downhole nuclear spectroscopy tool is receivable therein. There is fill material between the outer liner and the inner liner, the material including a formation base material and an elemental standards material. The outer liner, the inner liner, and the fill material are configured such that an elemental standard measurement derived from a test using the insert apparatus is equivalent to an elemental standard measurement from a selected formation. | 09-20-2012 |
20130075617 | Scintillator Crystal Materials, Scintillators And Subterranean Detectors - Methods for pre-treating packaging materials of particular composition for use in conjunction with a scintillation crystal are disclosed. The packaging materials may comprise a reflecting material, an elastomer, a reflecting fluorocarbon polymer, a polymer or elastomer loaded with a reflecting inorganic powder (including a reflecting inorganic powder comprising a high reflectance material selected from the group comprising Al | 03-28-2013 |
20130134304 | METHOD AND APPARATUS FOR GAIN REGULATION IN A GAMMA DETECTOR - Methods and systems to determine and regulate the gain of gamma-ray detectors in tools equipped with neutron sources are provided. Gain regulation may be based on the gamma ray background generated in the tool by interaction of neutrons with the nuclei of some elements constituting the tool structure. Some chemical elements that are used in construction of the tool's mechanical parts and structure result in characteristic gamma ray lines in a measured energy spectrum. These lines can be used to calibrate the energy scale of the response of the detector, without any added calibration radio isotopic source. | 05-30-2013 |
20130187035 | WELL-LOGGING APPARATUS INCLUDING AZIMUTHALLY SPACED RADIATION DETECTORS - 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. | 07-25-2013 |
20130208841 | High Voltage Supply For Compact Radiation Generator - Disclosed is a radiation logging tool, comprising a tool housing; a compact generator that produces radiation; a power supply coupled to the compact generator; and control circuitry. Embodiments of the compact generator comprise a generator vacuum tube comprising a source generating charged particles, and a target onto which the charged particles are directed; and a high voltage supply comprising a high voltage multiplier ladder located laterally adjacent to the generator vacuum tube. The high voltage supply applies a high voltage between the source and the target to accelerate the charged particles to a predetermined energy level. The compact generator also includes an electrical coupling between an output of the high voltage supply and the target of the generator vacuum tube to accommodate the collocated positions of the generator vacuum tube and the high voltage power supply. | 08-15-2013 |
20130299687 | Neutron Wellbore Imaging Tool - A method and apparatus for obtaining neutron images of a rock formation are provided. The neutron images can be obtained from a tool which need not rotate to obtain neutron data from a plurality of azimuthal orientations. | 11-14-2013 |
20130299713 | Multiplier Tube Neutron Detector - A neutron detecting device using a neutron-reactive material as the source of charged particles to feed conventional dynode-based electron multiplier which not gas-filled (i.e., with | 11-14-2013 |
20130308753 | In-Situ Downhole X-Ray Core Analysis System - The disclosure includes an arrangement of X-ray generator(s) ( | 11-21-2013 |
20140001350 | Gas Detection And Quantification Method Using A Pulsed Neutron Logging Tool | 01-02-2014 |
20140034821 | WELL-LOGGING APPARATUS INCLUDING AZIMUTHALLY-SPACED, NOBLE GAS-BASED DETECTORS - A well-logging device may include a housing to be positioned within a borehole of a subterranean formation, and at least one radiation source carried by the housing to direct radiation into the subterranean formation. The well-logging device may also include noble gas-based radiation detectors carried by the housing in azimuthally spaced relation to detect radiation from the subterranean formation. A controller may determine at least one property of the subterranean formation based upon the detected radiation from the noble gas-based radiation detectors. | 02-06-2014 |
20140034822 | WELL-LOGGING APPARATUS INCLUDING AXIALLY-SPACED, NOBLE GAS-BASED DETECTORS - A well-logging device may include a housing to be positioned within a borehole of a subterranean formation and at least one radiation source carried by the housing to direct radiation into the subterranean formation. The well-logging device may also include noble gas-based radiation detectors carried by the housing to detect radiation from the subterranean formation. At least one of the noble detectors is at a first axial spacing from the at least one radiation source, and at least one other of the noble gas-based radiation detectors is at a second axial spacing from the at least one radiation source different from the first axial spacing. A controller may determine at least one property of the subterranean formation based upon the detected radiation from the noble gas-based radiation detectors. | 02-06-2014 |
20140084149 | USE OF SPECTRAL INFORMATION TO EXTEND TEMPERATURE RANGE OF GAMMA-RAY DETECTOR - A method is for detecting gamma rays using a gamma ray detector, and includes determining a first count of gamma rays having an energy in a first energy interval, using a controller coupled to the gamma ray detector. A second count of gamma rays having an energy in a second energy interval is determined, the second energy interval having a higher energy than the first energy interval, using the controller. A third count of gamma rays having an energy in a third energy interval is determined, the third energy interval having a higher energy than the second energy interval, using the controller. The second count of gamma rays is compensated for noise based upon a ratio of the second count and the third count, using the controller. | 03-27-2014 |
20140090890 | Detection Of Tool In Pipe - Methods and systems for determining whether a tool has been deployed below a drill pipe are provided. A downhole tool can measure various characteristics, which then can be analyzed to determine the likelihood of a tool having been deployed below the drill pipe. For example, density and porosity measurements can be affected by the presence of casing or drill pipe, and thus such measurements can provide an indication of whether the tool has been deployed below the drill pipe. | 04-03-2014 |
20140097336 | Apparatus and Methods for Measuring Formation Characteristics - An apparatus can measure characteristics of a formation surrounding a borehole. The apparatus includes a tool body having a neutron measurement section and a density measurement section. The neutron measurement section includes a neutron source and a neutron detector arrangement spaced in an axial direction from the neutron source. The density measurement section includes a gamma ray source and a gamma ray detector arrangement spaced in an axial direction from the gamma ray source. The neutron measurement section and the density measurement section are positioned in the tool body so that the sections overlap in the axial direction and are azimuthally spaced apart in the tool body. The tool body also includes shielding to block a direct signal path from the neutron source to the gamma ray detector arrangement and to block a direct signal path from the gamma ray source to the neutron detector arrangement. | 04-10-2014 |
20140251690 | Logging-While-Drilling Tool Incorporating Electronic Radiation Generator And Method For Using Same - Logging-while-drilling tools incorporating an electronic radiation generator, such as an electronic X-ray generator, and a method for using the same are provided. One example of such a logging-while-drilling tool may include a circumferential drill collar, a chassis disposed radially interior to the drill collar, and an electronic X-ray generator and an X-ray detector disposed within the chassis. The electronic X-ray generator may emit X-rays out of the logging-while-drilling tool into a subterranean formation. The X-ray detector may detect X-rays that return to the logging-while-drilling tool after scattering in the subterranean formation, which may be used to determine a density and/or a lithology of the subterranean formation. | 09-11-2014 |
20140263997 | RADIATION DETECTOR FOR WELL-LOGGING TOOL - A radiation detector is used in a well-logging tool for positioning in a wellbore of a geologic formation. The radiation detector includes a photomultiplier housing and a scintillator housing. A housing coupler joins together opposing ends of the photomultiplier housing and scintillator housing. A photomultiplier is contained within the photomultiplier housing and a scintillator body is contained within the scintillator housing. A scintillator window is secured to the housing coupler. | 09-18-2014 |
20140325828 | METHOD OF MAKING A WELL-LOGGING RADIATION DETECTOR - A method for making a well-logging tool for positioning in a wellbore of a geologic formation includes forming a radiation detector by securing a scintillator window and a scintillator housing together and joining together opposing ends of a photomultiplier housing and a scintillator housing. The method further includes securing the scintillator window to the scintillator housing with a brazed joint. The radiation detector is positioned within a well-logging housing. | 11-06-2014 |
20140339408 | Scintillation Detector Package Having Radioactive Support Apparatus - A radiation detector package includes a support apparatus at least part of which is constructed from a naturally occurring radioactive material. A scintillator is associated with the support apparatus. The support may include a detector housing carrying a photodetector and the scintillator, and the detector housing may be constructed from the naturally occurring radioactive material. | 11-20-2014 |
20140346337 | Well-Logging Tool With First And Second Azimuthal Radiation Detectors And Related Methods - 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. | 11-27-2014 |
20150014544 | Integrated Coupling Of Scintillation Crystal With Photomultiplier In A Detector Apparatus - A scintillator type radiation detector package is provided including a scintillation crystal directly coupled to the window of a photomultiplier. A scintillator package is also provided having a longer life at wellbore temperature with minimal deterioration of a hygroscopic scintillation crystal(s). Direct optical coupling of the scintillator to the photomultiplier reduces the amount of light lost at coupling interfaces and improved detection resolution over the conventional structures having separate packages for crystal and photomultiplier. | 01-15-2015 |
20150055747 | Energy Radiation Generator With Bi-Polar Voltage Ladder - A well-logging tool may include a sonde housing, and a radiation generator carried by the sonde housing. The radiation generator may include a generator housing, a target carried by the generator housing, a charged particle source carried by the generator housing to direct charged particles at the target, and at least one voltage source coupled to the charged particle source. The at least one voltage source may include a voltage ladder comprising a plurality of voltage multiplication stages coupled in a bi-polar configuration, and at least one loading coil coupled at at least one intermediate position along the voltage ladder. The well-logging tool may further include at least one radiation detector carried by the sonde housing. | 02-26-2015 |
20150055748 | Energy Radiation Generator With Uni-Polar Voltage Ladder - A well-logging tool may include a sonde housing and a radiation generator carried by the sonde housing. The radiation generator may include a generator housing, a target carried by the generator housing, a charged particle source carried by the generator housing to direct charged particles at the target, and at least one voltage source coupled to the charged particle source. The at least one voltage source may include a voltage ladder comprising a plurality of voltage multiplication stages coupled in a uni-polar configuration, and at least one loading coil coupled at at least one intermediate position along the voltage ladder. The well-logging tool may further include at least one radiation detector carried by the sonde housing. | 02-26-2015 |