Abstract: A method of monitoring the density of a subterranean fluid comprises the steps of: using a subterranean radiation detector to obtain measurements over a plurality of time intervals of the amount of natural background radiation traversing said fluid, and calculating the relative density of said fluid at each of said time intervals from said measurements.

Abstract: A formation fluid analysis tool has an optical probe that is inserted into the formation. The optical probe carries an internal reflectance crystal and is inserted into the formation so as to get past the mud cake, the flushed zone and the invaded zone and thus be in contact with virgin formation fluid. An acousto-optical tunable filter (AOTF) transmits a single wavelength of light from a broad band light source, the wavelength being controlled by a microwave signal from a processor. This monochromatic light is carried by an optic fiber to the internal reflectance crystal where it undergoes total reflection at the crystal faces in contact with the formation fluid. An evanescent wave propagates into the fluid with a depth of penetration related to the absorption of the light in the fluid. The reflected light carries information about this absorption which is determined by the chemical composition of the fluid. A return fiber conveys the reflected light back to a spectrometer.

Abstract: The invention is a stationary radiation detection tool that provides an azimuthal indication of the location of subterranean radiation sources. In one embodiment, the tool has four gamma ray sondes, each of which receives gamma rays from a discrete sector of surrounding formation.

Abstract: A method and probe for subterranean determination of the concentration of a substance has a light-conducting optical fiber running from above the ground to a measurement cell below the ground. The system can be used effectively for fluorescent markers to track the ground water flow.

Abstract: A method and apparatus is provided for determining OBM filtrate fraction in a downhole fluid sample. One embodiment of the method is used when there is significant difference between the coloration of formation fluid and the coloration of OBM filtrate. Another is used when there is little or no difference between the coloration of formation fluid and the coloration of OBM filtrate. Another determines GOR of formation fluid corrected for OBM filtrate contamination. Another determines OD of formation fluid corrected for OBM filtrate contamination. Another determines conditions that would render optical density measurements invalid and sample capture premature. Another predicts the reduction of filtrate fraction for a specific extended pumping time. Another initiates sample capture when computed contamination fraction exhibits stable asymptotic convergence.

Abstract: The present invention provides systems utilizing fiber optics for monitoring downhole parameters and the operation and conditions of downhole tools. In one system fiber optics sensors are placed in the wellbore to make distributed measurements for determining the fluid parameters including temperature, pressure, fluid flow, fluid constituents and chemical properties. Optical spectrometric sensors are employed for monitoring chemical properties in the wellbore and at the surface for chemical injection systems. Fiber optic sensors are utilized to determine formation properties including resistivity and acoustic properties compensated for temperature effects. Fiber optic sensors are used to monitor the operation and condition of downhole devices including electrical submersible pumps and flow control devices. In one embodiment, a common fluid line is used to monitor downhole parameters and to operate hydraulically-operated devices.

Abstract: A logging tool system for analyzing the carbon dioxide concentration in a fluid sample downhole in a borehole. A chamber is filled with the fluid sample and is closed to isolate the fluid sample from the borehole. The interior chamber volume is expanded to decompress the fluid sample, and a transmitter discharges light in the mid-infrared range. A sensor measures the absorbance of mid-infrared light by the decompressed fluid sample and generates a signal representing the carbon dioxide concentration. Mid-infrared light absorbance in the range between 4.1 and 4.4 microns can be analyzed by the processor to identify the carbon dioxide concentration in the fluid sample, and infrared absorbance in the mid-infrared range between 3.2 and 3.6 microns can be analyzed to identify methyl and metheylene components. A wiper cleans the transmitter and sensor between readings to reduce measurement errors caused by fluid sample contamination.

Abstract: A method for determining the azimuthal direction of a maximum in a series of gamma ray count measurements that are each assigned to an azimuthal sector, comprising: determining the x- and y-components of the gamma ray counts for each sector, averaging the component values to obtain averaged x- and y-components, and calculating the corresponding aximuthal angle for the maximum by computing the arctangent of the ratio of the averaged y- and x-components.

Abstract: A method of locating in situ hydrocarbons in underground formations comprises illuminating the borehole wall with light such as visible, infrared or ultraviolet light or combinations of these, from a source in a tool such as a wireline logging tool or an LWD tool, detecting any fluorescent radiation with a detector in the tool and analyzing the florescent radiation to determine the presence of hydrocarbon in the formation. The tool is moved through the borehole while irradiating the formation and detecting fluorescence. The borehole wall is illuminated and fluorescence detected through a window in the tool which is pressed against the borehole wall with sufficient force to displace any mudcake. The window is made of a wear resistant material such sapphire or diamond and is conveniently secured in a wear resistant housing which might be made of tungsten carbide or the like.

Abstract: A system for determining a composition of radionuclides in, for instance, a mineral-containing material by detecting gamma and/or X-ray radiation emitted by the nuclides is disclosed. To that end, the system has a detector unit which supplies an electrical signal containing information about the intensity and energy of the emitted radiation and a signal processing system by which these electrical signals are further processed for determine the composition mentioned. The signal processing system further has an A/D converter to which the electrical signals are applied and a first computer unit which further processes signals supplied by the A/D converter for the purpose of determining the composition mentioned.

Abstract: A method for calibrating a logging tool that is exposed to an external energy spectrum, comprising the steps of: (a) providing a stabilization source that emits a stabilization signal having a known energy; (b) providing a receiver that receives a total spectrum that comprises the sum of the external energy spectrum and the received stabilization signal; (c) discerning the stabilization signal in the total spectrum by the steps of: calculating the centroid of the area under the total spectrum; adjusting the gain of the tool on the basis of the calculated centroid; dividing a portion of the spectrum that includes the known energy level of the stabilization peak into a number of windows of equal width, with an equal number of windows on either side of the stabilization peak energy; using the count rates in each of the windows to calculate a value D.sub.n that is proportional to the n.sup.

Abstract: A method of determining a holdup value for a multiphase fluid. A first holdup component is calculated using a first detection technique which is insensitive to small inclusions of a first fluid constituent (hydrocarbons) dispersed in a second fluid constituent (water). A second holdup component is also calculated using a second detection technique which determines a percentage of the small inclusions of the first fluid constituent that are dispersed in the second fluid constituent. The first and second holdup components are then combined to yield a total holdup value. The method can further compensate for displacement of the second fluid constituent by the small inclusions of the first fluid constituent. The second holdup component is preferably calculated by inferring a maximum heavy phase density (MHPD) of the multiphase fluid.

Abstract: A method for determining a volume fraction of water moving in a predetermined direction along a highly inclined conduit. The method includes measuring a fractional volume of water occupying the conduit at a plurality of locations along the conduit. An oxygen activation velocity of the water flowing in the conduit is determined at a plurality of locations along the conduit. A counting rate of a gamma ray detector used to measure oxygen activation is normalized with respect to the measured fractional volume of water. The normalized count rates of the gamma ray detector are characterized with respect to a relative velocity between the water and the detector. The step of characterizing is performed in portions of the conduit which are sloped so that gravity acts on the water along the predetermined direction. A fraction of the characterized counting rate represented by the oxygen activation counting rates measured along the conduit is determined.

Abstract: A method of locating in situ hydrocarbons in underground formations comprises illuminating the borehole wall with light such as visible, infrared or ultraviolet light or combinations of these, from a source in a tool such as a wireline logging tool or an LWD tool, detecting any fluorescent radiation with a detector in the tool and analyzing the florescent radiation to determine the presence of hydrocarbon in the formation. The tool is moved through the borehole while irradiating the formation and detecting fluorescence. The borehole wall is illuminated and fluorescence detected through a window in the tool which is pressed against the borehole wall with sufficient force to displace any mudcake. The window is made of a wear resistant material such sapphire or diamond and is conveniently secured in a wear resistant housing which might be made of tungsten carbide or the like.

Abstract: Apparatus and method for determining a liquid yield from a gas/condensate reservoir. The apparatus and method first determines the porosity at each depth of a reservoir, using open hole logging techniques, before the well within the reservoir is used for production. Once the well is being used for production, a pulse neutron capture logging device is used to provide RICS and RATO data at each depth within the reservoir. The apparatus and method combines the RICS and RATO data, along with the porosity data, to provide a yield plot of an estimate of the liquid yield of the condensate in the reservoir at each depth within the reservoir. The apparatus and method further compares estimates made to any actual production data from the particular well being estimated and corrects constants within the estimating method to cause the estimates to match the production data. This feedback mechanism provides a more accurate estimate of the yield.

Abstract: A scintillation detector (10) includes a scintillation crystal (14) and a shock absorbing member (76) circumscribing the crystal (14). A sleeve (98) circumscribes the shock absorbing member (76) which, in turn, is circumscribed by a housing (12). The sleeve (98) provides for substantial controlled radial loading on the crystal (14). A method of manufacturing the detector (10) includes placing the crystal (14) and shock absorbing member (76) into the sleeve (98), compressing the sleeve 98 and inserting the compressed sleeve (98) into the housing (12) such that the sleeve (98) substantially maintains its compression. The radial stiffness causes vibration induced counts to occur at an excitation frequency which is above the operational bandwidth of the radiation measurements, thereby excluding vibration induced counts for radiation measurements.

Abstract: A borehole tool analyzes the composition of gases flowing from a formation. The tool includes an optical fluid analyzer (OFA) and a gas analysis module (GAM). The OFA determines when fluid flowing into the tool has become substantially only gas. The gas is then diverted to the GAM, thereby avoiding the possibility of oil depositing itself on a optical window and interfering with a proper analysis. The GAM includes a near infrared ray light source, at least one photo-detector, a gas sample cell (or cells) having portions with different path lengths, each portion having an optical window, and fiber optics which direct light in first paths from the source to the sample cell, and from the sample cell to the photo-detectors. By providing cells with different path lengths, issues of dynamic range are obviated.

Abstract: A method for determining total clay content of an earth formation based on elemental concentration logs obtained from a logging tool. This method avoids the need for obtaining an aluminum concentration measurement. First, the concentrations of a plurality of elements in the formation are determined without measuring an aluminum concentration. Then, at least the silicon, calcium, and iron concentrations are combined in accordance with a function determined by regression analysis to produce an estimate of the total clay content.

Abstract: The system relates to a system for determining a composition of radionuclides in, for instance, a mineral-containing material by detecting gamma and/or X-ray radiation emitted by the nuclides. To that end, the system comprises a detector unit (2,6, 10) which supplies an electrical signal containing information about the intensity and energy of the emitted radiation and a signal processing system by which these electrical signals are further processed for determining the composition mentioned. According to the invention, the signal processing system further comprises an A/D converter (14) to which the electrical signals are applied and a first computer unit (26) which further processes signals supplied by the A/D converter for the purpose of determining the composition mentioned.

Abstract: A production logging device, insertable into a cased or uncased wellbore for determining concentration of specified components in flowing production fluid, is provided having a tool body sized smaller in diameter than the wellbore so that flowing fluid production is not blocked. A line is connected to the tool body by which movement of the tool body within the wellbore casing can be selectably controlled from a remote location, and by which information signals can be communication from the tool body to the remote location. An infrared radiation source operatively connected to the tool body. A plurality of infrared transmission sites are circumferentially spaced around the tool body directed so that infrared radiation from the infrared radiation source is transmitted through flowing production fluid in the wellbore.

Abstract: Radioactive contamination on tubing is detected as the tubing is withdrawn from a wellbore. The tubing is moved past a detector located on the wellhead, preferably through an annular shaped detector, and means responsive to the detected level of radiation exceeding predetermined limits activate both an alarm to gain the operator's attention and means to apply indicia to the contaminated tubing.

Abstract: A system and method for evaluating a geological formation is described which compares actual wireline log measurements from a number of wireline logging tools to predicted tool response logs. The system and method uses a forward model of each tool response, given a formation description, to predict a set of wireline logs. Comparing the predicted logs with the actual measured logs yields a mismatch error. The system and method iteratively adjusts the formation description to minimize the mismatch error to obtain a "best" formation description. In one form, the formation description includes petrophysical properties (porosity, density, saturation) and geometry properties (dip, bedding, invasion). In a more complicated form, the formation description also includes a model of petrophysical mixing laws and formation material content. In the special case of a horizontally layered formation and linear tool response models, there exists a computationally efficient version of the system and method.

Abstract: Images of rock formations below the earth's surface can be obtained on a microscopic scale. A borehole tool uses a seal to isolate an interval of the formation from borehole fluids which are outside the seal. A probe of the tool engages a wall of the formation and then draws formation fluid from the formation into the interior of the tool. The tool then produces an optical image of the formation which indicates rock texture. The seal can comprise a pad, inflatable packers, compressional packers, or cement plugs. The images of the formation can be obtained with electro-optic imagers such as charge-coupled devices (CCD) or a camera operating in the visible and/or near infrared range, or with ultrasonic transducers operating in the sub-MHz to mid GHz range, for example. The near infrared range provides an optical image of the formation through opaque fluids such as oil based muds or oil itself.

Abstract: An apparatus and method for protecting downhole electronic components and for monitoring the deterioration of such components. The electronic components are positioned within a tool recess, and a vacuum is drawn on the recess to remove oxygen, water vapor, and other contaminants from contact with the electronic components. In one embodiment of the invention, insulating fluid or an inert gas can be placed in the recess to isolate the electronic components. The seal integrity of the recess can be tested before the tool is run into the well or before the tool is set in the well. A pressure sensor monitors the deterioration of the vacuum, or fluctuations in the pressure of the insulating fluid or inert gas, to detect leakage of well fluids into the recess, leakage of gas away from the recess, or to detect gases formed from corrosion of the electronic components.

Abstract: A method is disclosed for determining the thickness of cement that has been placed in an annulus between a casing string and a wellbore penetrating a formation, wherein the method includes the steps of: logging the amount of radioactivity emitted by a radioactive material in the formation prior to emplacement of the casing and cement, including in the cement an amount of the radioactive material, placing the casing and cement in the wellbore, logging the amount of radioactivity emitted by the radioactive material and transmitted through the casing and calculating the amount of cement in the annulus by determining the amount of the radioactive material in the annulus.

Abstract: A method of quantitative analysis of free organic components in a drilling fluid comprising separating solid and liquid components of the drilling fluid using a non-filtering technique such as centrifuging, mixing a sample of the liquid components with a solution of an inorganic carrier such as 2M KBr and analyzing the mixture using infrared spectroscopy so as to determine the amount of organic components in the mixture and deriving the amount of free organic components in the drilling fluid from this analysis. In one embodiment, the mixture is dried to leave a solid mixture of the organic components and the carrier. In this case, the sample is preferably analyzed using a reflectance technique such as diffuse reflectance infrared spectroscopy. In another embodiment, the mixture is analyzed as a liquid, preferably using a direct transmission technique. In both the liquid and solid cases, Fourier transform infrared spectroscopy is preferred.

Abstract: A well logging scintillation detector has a gamma ray detector crystal with a window at one end and a single or multi-layer cladding surrounding the remainder of the crystal, with a reflective layer surrounding the cladding. The reflective layer, which may be a thin, high reflective metallic layer or reflective particles in a resin matrix, is surrounded by an elastomer with reflective particles which is surrounded by a casing which is a metal. The casing is surrounded by one or more outer casings, which are separated from each other by elastomeric members. A resilient base is formed opposite the window. The window has a flat glass plate connected to the crystal with an optical coupler, and a clear elastomer optically coupled to the plate. A larger plate is optically coupled to the elastomer, and the larger plate is sealed to one or more of the outer casings by inter-fitted corrugated rings of glass and metal which entrap epoxy, which fills the corrugations.

Abstract: A method for determining density of a formation. The method includes irradiating the formation with gamma rays having energy consistent with Compton scattering. Gamma rays are measured at axially spaced apart locations. Two of the axially spaced apart locations are at an equal distance and in opposite directions relative to the source of gamma rays. The distance is smaller than the spacing of another one of the spaced apart locations. An apparent density for each spaced apart location is determined from the counts. Differences are calculated in apparent density between each one of the spaced apart locations, and a correction factor is determined for apparent density at each spaced apart location, thereby determining the density of the earth formation. In a preferred embodiment, determining correction factors is performed by a neural network using the differences in apparent density as an input vector.

Abstract: A system for determining formation gas saturation in a cased wellbore which includes a neutron logging tool having a source, a first neutron detector offset towards the wellbore primarily sensitive to the wellbore and a second detector spaced further from the source and offset towards the formation, so that the second detector is sensitive primarily to liquid-filled porosity in the formation. The detectors are encased in a neutron moderator. The system includes a method of determining gas saturation in the formation by measuring count rates at the detectors, generating a wellbore gas saturation from the first detector counting rate, generating a ratio of counting rates of the second and first detectors to generate a value of liquid-filled porosity in the formation, and calculating a gas saturation in the formation by combining the liquid-filled porosity with a measurement of total porosity.

Abstract: The invention concern a combination well logging device adapted to be moved inside a borehole to measure the properties of geological formations through which the borehole passes.The device according to the invention comprises a series of elongate logging sections mounted end to end, including a first section adapted to be maintained with a generatrix applied against the wall of the borehole, a second section comprising a body and a measurement pad adapted to be spaced radially from the body for application against said wall, a third section adapted to be kept space from said wall, and first and second hinges connecting the second section to the first and third sections respectively in order to allow respective angles of inclination between the second section and the first and third sections.

Abstract: A method of analyzing a drilling fluid comprising subjecting a sample of the fluid to an XRF analysis technique and comparing the results obtained with a calibration model to determine the amount of one or more components of the fluid present in the sample. The method is particularly useful for determining solids in the fluid such as barite and can be combined with an FTIR technique which is sensitive to other components of the fluid. A PLS algorithm is used to construct the model from the spectra.

Abstract: A standoff compensation system is disclosed for use in an LWD system implementing gamma density and/or neutron porosity measurements. An acoustic transducer is provided to measure the standoff distance between the logging tool and the borehole wall. The present invention includes a downhole processor for determining a weighting factor for the density and/or porosity measurements based upon the measured standoff distance. The weighting factor can either be calculated by the downhole processor according to a predetermined weighting function, or can be retrieved from a pre-calculated look-up table in ROM. The processor then multiplies the weighting factor by the count data from the sensor to determine a weighted count value. The weighted count values are accumulated during an averaging period and normalized, so that a single normalized count value can be generated and either stored in downhole memory, used immediately, or transmitted by telemetry to the surface.

Abstract: A photon detector includes an activated lanthanide beryllate crystal, such as activated lanthanum beryllate, as a scintillator to detect photons. In one embodiment, the lanthanide beryllate crystal is doped with cerium.

Abstract: System for the input and output of data on a two wire system with a downhole well tool which has a system with sensor devices, a processor, a clock, a memory and a voltage/current communications device which are all powered by a d.c. battery. A phone jack and phone plug connection at the earth's surface enables an operator with a controller to input and output data to the well tool without disassembly and enables setting the clock in the well tool to a selected real time value. This enables synchronization of real time values of data recordings for different tools.

Abstract: A measurement system for fiber sensors includes a broadband light source 11 providing continuous light which is launched into a fiber 20 having a plurality (or string) of Bragg grating sensors 24, 28, 34. Each sensor has a predetermined central reflection wavelength which shifts as a function of applied strain. Reflected light 40 from the sensors 24, 28, 34 are fed to a plurality of optical bandbass filters 50, 64, 78, each having a monotonic region in a passband corresponding to one of the sensors. Each monotonic region transmits the reflected wavelength from a corresponding sensor. Light 52, 66, 80 is passed from the filters 50, 64, 78 to optical detectors 54, 68, 82 each providing an electrical signal having a magnitude related to transmission of the filter at the reflection wavelength of the sensor. Optional demodulators 58, 72, 86 are connected to each of the detectors 54, 68, 82 if the light source 10 is modulated.

Abstract: Method and apparatus for optimizing the extraction of aromatics from waxy distillates and the dewaxing of waxy raffinates in the manufacture of lubricating oils.

Abstract: A method and apparatus for detecting natural gamma-ray signals of an earth formation and correcting these gamma-ray signals for effects from borehole gamma-rays. Gamma-ray signals are detected at two detector locations in the borehole. The borehole effects are derived from the differences between the detected signals. After the borehole effects are determined, the detected gamma-ray signal is corrected for these effects and measurements of the formation elements are derived. A differential signal between the two detectors is created by excluding a small volume of borehole fluid from one of the detectors from the borehole fluid, before detecting gamma-rays at both detectors. The excluder displaces a known volume of borehole fluid equal to the volume of the excluder. Both detectors record gamma-ray generated from the formation and borehole. The additional volume of borehole fluid at one detector causes the detected signals to be different.

Abstract: In a method of logging a well in a subterranean formation which formation has been fractured by injecting proppant tagged with at least one radioactive material into the formation through the well, the improvement comprising: utilizing a spectral gamma-ray tool in performing the logging. By analyzing one or more selected ratios of counting rates at certain energy areas of the spectrum one can determine the vertical height of the fracturing in the formation.

Abstract: The Fiber Optic Photochemical Oxidation Decontamination (FOPOD) method and apparatus is provided for in-situ remediation of aqueous leachate plumes. The apparatus consists of a well-type housing with numerous holes drilled for a distance equal to the vertical depth of the leachate plume. The bottom of the housing is capped. Through the holes are threaded numerous specialty optical fibers, being encased in the housing and forming bundles above ground. The method comprises ultraviolet light perpendicular to the bundles being transmitted sub-surface by the optical fibers which exit each hole within the plume. Hydrogen peroxide injected into the housing also enters the plume through the numerous holes in the housing. The reaction products are carbon dioxide and water.

Abstract: Apparatus for helping predict the occurrence of an earthquake or a volcanic eruption by detecting and recording the direction of a neutron flow generated in the earth's magma and the intensity of the neutron activity.

Abstract: Methods for quantifying the oil and water fractions of a fluid stream. A first method broadly includes making optical density (OD) measurements of the fluid stream by detecting photons of a first predetermined energy where the oil and water absorption characteristics are substantially identical (e.g., 1710 nm wavelength), and determining the oil and water fractions f.sub.o and f.sub.w according to OD.perspectiveto.f.sub.w .alpha..sub.w l+f.sub.o .alpha..sub.o l where .alpha..sub.w and .alpha..sub.o are related to the absorption coefficients of the oil and water at the predetermined energy, l is the path width of the fluid stream, and f.sub.w +f.sub.o =1. A second method which eliminates scattering effects utilizes the photons at the first predetermined energy and further utilizes photons of a second predetermined energy which is sufficiently close to the first predetermined energy such that the oil fraction is a linear function of the OD over the energy range.

Abstract: A collective fluid inclusions volatiles sample is released from each of a plurality of sedimentary rock samples and analyzed as it is being released to determine composition thereof. Compositions are used for mapping the earth's subsurface.

Abstract: A method of quantitative analysis of drilling fluids comprising subjecting an untreated wet sample of the fluid to a reflectance infrared spectroscopy technique, typically attenuated total reflectance spectroscopy, and comparing the spectrum obtained with spectra obtained from calibration samples of fluids of known composition. The sample can be obtained directly from the flowing mud with no preparation or alternatively the sample might comprise a prepared sample which is re-suspended in a liquid phase carrier. The sample can also be analysed for non-spectral properties which might also provide useful information in conjunction with spectral data. The method requires little or no sample preparation and can be used to quantitatively analyse both water-based and oil-based drilling fluids using a continuous in-line and/or on-line arrangement.

Abstract: A borehole logging tool is lowered into a borehole traversing a subsurface formation and a neutron detector measures the die-away of nuclear radiation in the formation. Intensity signals are produced representing the die-away of nuclear radiation as the logging tool traverses the borehole A signal processor, employing at least one neural network, processes the intensity signals and produces a standoff-corrected epithermal neutron lifetime signal to correct for standoff from the borehole wall encountered by the detector as the logging tool traverses the borehole. The signal processor further generates a porosity signal from the standoff-corrected epithermal neutron lifetime signal derived from measurements in borehole models at known porosities and conditions of detector standoff. A log is generated of such porosity signal versus depth as the logging tool traverses the borehole.

Abstract: A collective fluid inclusions volatiles sample is released from each of a plurality of sedimentary rock samples and analyzed as it is being released to determine composition thereof. Compositions are used for mapping the earth's subsurface. The sample is released by an automated crushing mechanism and analyzed by a system of concurrently operated mass spectrometers each scanning a specific set of mass to charge ratio responses.

Abstract: Methods for distinguishing among oil samples, and more particularly between a fluid containing oil base mud and formation oil samples are described. The methods all rely on the discovery that the optical absorption spectrum of all crude oils in the visible and near infrared spectra can be described according to the equation OD=ae.sup.Eb, where (OD) is a measured optical density, (b) is a value between 0.37 and 0.55 chosen according to the wavenumber (E) and can be chosen as a constant equal to 4.6.times.10.sup.-4 cm, and (a) is an unknown which classifies the crude oil. By making measurements and solving for (a), a crude oil can be classified. In a flow stream which has a changing oil content, such as may be obtained by a borehole tool which obtains fluid samples from the formation, by monitoring the unknown (a), a determination may be made as to when a formation oil is being obtained as opposed to a mud filtrate.

Abstract: Disclosed herein is a radiation detector providing for the in situ automatic sampling of fluids containing substances emitting radiation, especially Cerenkov radiation. The detector permits sampling within well casings and is self-purging such that no additional provisions must be established for the storage and disposal of contaminated fluids.

Abstract: An apparatus and method utilize a neutron sensitive medium in which initially existing atoms of the medium are divided into particles, reaction energy and neutron energy. The medium undergoes polarization in response to the reaction energy and the neutron energy. This produces an electrical charge gradient which is proportional to the energies and which can be sensed and analyzed to indicate just the neutron energy.

Abstract: The present invention relates generally to increasing the accuracy of MWD nuclear based measurement systems. Specifically, the present invention provides a secondary measurement system for determining the tool displacement from the bore-hole wall for calculated compensation of nuclear measurement data.

Abstract: The energy-to-channel response of a bismuth germanate scintillator (BGO) gamma ray spectra measurement system is calibrated by use of the 10.2 MeV gamma ray peak originating from epithermal neutron capture within the BGO crystal as a calibration reference line. The 10.2 MeV peak is located by successively fitting the detected spectrum to the combination of a gaussian-shaped gamma ray peak and an exponentially-shaped background, beginning at the upper end of the spectrum and successively sliding the fitting window downwards until the peak is reached. Once the 10.2 MeV peak has been located, the spectral gain is adjusted to shift the peak to an assigned calibration channel location adjacent the upper end of the overall spectral window.