Abstract: A borehole apparatus for analyzing the composition of a formation fluid includes a chamber that contains the fluid, and a light source that directs light through the fluid in the chamber. The optical path of the light is modified such that an output fiber optic bundle receives indirect light through the fluid. One embodiment comprises a diffuser in the optical path, which forward scatters the light to the output fiber optic bundle. Another embodiment comprises the misalignment of an input fiber optic bundle relative to the output fiber optic bundle. Collimators can be subsituted for the fiber optic bundles.

Abstract: Radioactive tracer well logging has typically utilized iodine as a source of gamma rays. Bromine-82 is utilized as the source of gamma radiation in this process. Because bromine-82 emits more energetic gammas and more gammas per decay, less activity is required. Because bromine has a shorter half-life and has less of a tendency to concentrate in a human's thyroid gland than iodine, consequences of incidental releases are less severe.

Abstract: A method and apparatus is described for determining petrophysical properties of porous media by the use of light transmission through the media. Specifically, by using a highly collimated light source, preferably a laser, the permeability, grain size, wettability, porosity and clay swelling behavior of a sample can be determined on the scale of millimeters. A calibration curve or function is first established to correlate light transmission through a slab of sandstone on the order of 5 to 10 mm under known conditions. This curved is then used to determine unknown conditions by measuring light transmission and comparing the values to those on the curve. Other applications for the phenomenon of light transmission through porous media are disclosed whereby conditions in a flowing stream of liquid can be monitored by use of light transmission. Specifically, changes in the refractive index and immiscible contamination can be detected.

Abstract: A method and apparatus for determining the presence of at least one naturally radioactive element in an earth formation surrounding a borehole, wherein, for each depth in the borehole, a spectrum is made of the gamma rays detected in several energy channels, and expressed as U=S Y, where "Y" is the elemental yields and "S" is a composite spectra matrix made of individual standard spectra characteristic of a given borehole environment; yields Y are then calculated. One thus determines a borehole correction factor from the general relationship between the borehole parameters, the standard spectra and the measured spectra. Finally, the yields are corrected for borehole effects by applying the correction factor.The correction factor is energy independent, at least for energies above a given threshold, and is also independent from the radioactive elements.

Abstract: A monitoring device for determining presence of native hydrocarbons downward along a drilled borehole by analyzing upcoming drilling mud returning to the reserve pit. The device includes a short pulse laser of selected output wavelength disposed at a remote location to couple output light into a fiber optic cable that leads to a position at the reserve pit viewing the returning drill mud. The device employs optical coupling to project any hydrocarbon fluorescence light for return along the fiber optic cable to the remote position for reflection through a monochromator, and the fluorescence light is processed through a photomultiplier tube and data acquisition system to derive charcteristic decay lifetime signatures to distinguish between native hydrocarbons and any lighter oils contained in the drilling mud.

Abstract: A pulse height analyzer for spectrocopy thermal multigate decay well logging systems is disclosed and has an input section comprising a peak time determining circuit locating a peak occurrence. The peak is determined relative to a threshold voltage determining circuit. On peak detection, a timing signal is formed for a control circuit. This operates a sample and hold switch at the output of an amplifier for the input. This switch inputs to an A/D converter driving a buffer. Various handshake signals cooperate with a telemetry system to transfer the peak time A/D valve for pulse height measurement.

Abstract: A downhole probe for use in conditions of high vibration or shock comprises a vibration-sensitive inner unit having a cylindrical outer surface, an outer casing having a cylindrical inner surface within which the inner unit is accommodated, and an intermediate vibration-damping composite sleeve extending between said inner and outer surfaces. The composite sleeve has two coaxial sleeve parts fitting one within the other and consisting of an apertured metal sleeve part and an elastomeric sleeve part having axial ribs which extend through axial slots in the apertured sleeve part. The axial ribs of the elastomeric sleeve part engage the inner surface of the outer casing and inner surfaces of the elastomeric sleeve part engage the outer surface of the inner unit so as to support the inner unit within the outer casing in such a manner as to provide efficient isolation of the inner unit from external vibration and shock.

Abstract: A fluid flow and simultaneous fluid density measuring device is set forth. The preferred embodiment incorporates a sonde having a lower inlet port, an upper outlet port, a lengthwise tube extending through the sonde and connected with the ports. A packer provides external isolation to direct all fluid flow into the tube. A float within the tube is buoyantly raised primarily as a function of fluid velocity and fluid density, and the position of the float is measured by placing a radioactive source in the float and measuring the count rate at spaced detectors to ascertain float location. Fluid is simultaneously measured by determining the radiation count rate attenuation of the fluid. With other fixed parameters and measurement of the float position and fluid density, the fluid flow rate can be determined. Both method and apparatus are set forth.

Abstract: In order to properly treat the tubing of an oil producing borehole, and prevent hazard to personnel at the oil production site, the contamination of tubing by the formation of scale or radioactive deposits on the inner wall thereof is determined by measurement of the low-level radiation emitted by the scale and calculation of the radiation level which would be detected in the vicinity of the outer wall of the tubing in the absence of contributions by the radioactivity of surrounding earth formations. This is accomplished by a logging tool and method which includes a sonde which includes a detector and is lowered in the tubing to detect and count the gamma rays emitted by the scale or radioactive deposits at different depths in the borehole tubing.

Abstract: This disclosure is directed to a scintillation crystal surrounded by a sleeve and having a window formed therein. The scintillation crystal has end located first and second photomultiplier tubes which provide output signals. A scintillation event observed in the crystal is seen by both photomultiplier tubes and both form output signals. The output signals have a relationship determining the point of impingement along the length of crystal of the photon gamma radiation; in turn, that photon is located relative to a surrounding shield having a helical window formed therein so that the relative angle of impingement can be determined. The relative angle is then converted into the absolute angle relative to the well borehole by referencing a north seeking gyroscope supported by the sonde. The output signals are also used to determine the energy of the impinging gamma radiation using well known pulse height analysis spectroscopy techniques.

Abstract: The MWD methods and MWD apparatus disclosed herein include methods and apparatus for rotating a directionally-responsive radiation sensor having an outwardly-directed response axis in a borehole. These MWD methods and MWD apparatus further includes methods and apparatus for obtaining a series of successive measurements representative of a geometrical parameter of the borehole as well as a characteristic of the adjacent earth formations as the sensor scans circumferentially-spaced locations on the walls of a borehole interval. Methods and apparatus are provided for determining the means of the successive measurements as well as the standard deviation of the successive measurements and then combining these computations for providing output signals that are uniquely corrected in accord with variations in the traverse cross-sectional configuration of the borehole for providing indications representative of the desired formation characteristic as well as indications respresentative of the borehole configuration.

Abstract: A borehole apparatus for analyzing the composition of a formation fluid is disclosed and generally comprises a testing chamber, a means for directing a sample of fluid into the chamber, a light source which emits at least near infrared rays, a spectral detector, a data base means, and a processing means. The light source is preferably an incandescent lamp and the testing chamber includes a window which is substantially optically transparent to at least one near infrared light, and preferably also the near ultraviolet and visible light of the source. The light source is directed at least partly towards the window in the chamber either via collimation or fiber optics. The spectral detector means is preferably a spectrometer which detects and measures the spectra of the light which has been transmitted through and the light which is backscattered by the fluid sample. The preferred data base means stores the spectra at different pressures and temperatures of water, gas, and a plurality of oils.

Abstract: The invention is a neutral atom (and/or molecule) matter-wave interferometer (and/or set of interferometers) that can be used as an inertial sensor with a sensitivity exceeding that of conventional mechanical sensors and multiple circuit optical interferometers (including ring lasers) by many powers of ten. An interferometer in which matter-wave propagation beam paths enclose a finite area will sense rotations via the Sagnac effect. One with the paths displaced from each other will sense acceleration plus gravity. Interferometers with paths that follow a figure-eight pattern yield a gravitational gradiometer. Laser cooling and slowing of a beam of neutral atoms provides a low energy nearly monochromatic source. Diffraction gratings are employed as beam splitters. Such gratings may consist of apertures in a sheet of solid material, near-resonant standing-wave laser beams, or crystal faces.

Abstract: A method for porosity determination in porous media such as earth and rock core samples by x-ray computed tomography in which a sample of the porous medium is scanned after saturation with a first reference fluid and then after saturation with a second reference fluid to determine the linear attenuation coefficients of the sample saturated with the respective fluids. The method includes determining the linear attenuation coefficients of the respective fluids and comparing the difference in the attenuation coefficient of the respective fluids and the attenuation coefficient of the samples as saturated with the fluids to determine the porosity of the porous medium. The respective fluids may be a gas and a liquid wherein the x-ray absorption of the two fluids is significantly different. The fluids may be different liquids or a single gas at different pressure conditions to obtain the different absorption characteristics.

Abstract: A post-acceleration detector for a mass spectrometer comprises a conversion electrode bombarded by an ion beam thereby emitting charged particles having a polarity opposite to that of the ion beam, a charged particle detector amplifying and detecting the charged particles, and a mechanism for moving the conversion electrode relative to the charged particle detector according to the energy of the ion beam.

Abstract: The present invention relates to a device and method for using a logging probe of small diameter with respect to a well in which it is to operate. The device of the invention is characterized in that it includes a widener for widening the diameter of said probe.

Abstract: In logging operations in a well borehole where difficulties arise in retrieval of the logging apparatus, drilling through the logging tool is sometimes necessary. This disclosure sets forth a radioactive source material which permits this remedial step. The radioactive source material is either a short half life radioactive isotope or is in fluid form. In fluid form, it is purged out of the sonde by means of a motor controller triggered into operation to operate a piston and cylinder pump arrangement. The outlet from the cylinder is through a flow line and check valve. The purged radioactive source material is then flushed to the bottom of the well borehole and is ideally forced into a selected formation for disposal, thereby safely removing the radioactive materials from the sonde to permit destruction of the sonde.

Abstract: A method of radioactive well logging for use in well operations wherein hydraulic fracturing material, including radioactive isotopes, is injected from a steel-cased well bore 31 into surrounding earth formations 33. Low energy gamma ray emitting radioisotopes are selected for tagging the liquids phase of the fracturing material and high energy gamma ray emitting radioisotopes are selected for tagging the solids phase. The relative amount of low energy radioisotope material inside the well bore 31 relative to the amount outside the casing 35 is determined to minimize the interfering effects of borehole tracers in determining concentrations of the high energy tracers in the formations. The procedure includes detecting the intensity of gamma radiation from the tracers in the borehole and surrounding formations by a detector 38 in the borehole in proximity to the injection zones and obtaining data representative of the radiation intensity.

Abstract: Formation of scale from radioactive components is monitored with a radiation detector. Upon indication of initiation of scale formation in a system, treatment with inhibitor is carried out.

Abstract: A method and apparatus for determining photoelectric absorption cross-section is disclosed. A photon source is operably connected to a target chamber. A collimator connected to an opposite end of a sample chamber is oriented to receive photon energy from the source. A gamma ray detector is used to measure photon energy.

Abstract: A high-temperature well logging instrument of the scintillation detector type includes a plastic scintillation element susceptible to softening and deformation at high operating temperatures. To maintain the shape of the scintillation element at such high temperatures, a metal retaining cup holds the scintillation element in its original shape. The retaining cup with the scintillation element inside is capped at its open end by a silicon rubber pad that is transparent to photons generated by the scintillation element in response to detected radiation. A biasing spring holds the end face of a photomultiplier tube against the silicon rubber pad so as to sandwich the pad between the photomultiplier tube and the open end of the metal retaining cup. Such a configuration maintains excellent optical coupling between the scintillation element and photomultiplier tube during high-temperature well logging.

Abstract: A method and apparatus (43) are disclosed for natural gamma ray spectral logging of a well borehole (41) to determine the abundances of uranium (U), potassium (K), and thorium (Th) gamma rays in the earth formations (46) adjacent to the borehole (41), and for compensating for borehole attenuation effects upon such gamma photons caused by scattering and absorption phenomena in the materials (42) within the borehole.

Abstract: A method for determining the density of substrata by means of a radiation source K comprising a collimator (1) and of a detector comprising a collimator (3), by which method the direction of radiation may optionally be changed in relation to the direction of detection, and the change of the detected signal may be measured. According to the invention the direction of radiation and the direction of detection are situated in substantially the same plane. By deducting the signal of the desirable depth of measurement from a somewhat greater depth of measurement, substantially only the signal originating from singly scattered radiation is obtained, and as a result it will be possible to measure the density at greater depth than previously. On the basis of a spectrum analysis of the spectrum originating from the measurement, the variation of the density with the depth could be obtained.

Abstract: The present invention comprises a method for determining the transition point between a portion of a curve comprising a statistically single exponential function and another portion of the curve comprising the composite of said exponential function with another function. The method of the present invention is useful in determining which portion of a composite decay curve is statistically equivalent to a single exponential function. The method of the present invention is particularly useful in the oil and gas industry in connection with the rapid and accurate determination of the decay constant of the formation surrounding a borehole. In the method of the present invention, the measured decay function following radiation of the formation with a burst of fast neutrons is integrated in a plurality of contiguous time gates between the end of the neutron burst and the decay to background radiation levels.

Abstract: Logging apparatus and methods for detecting first signals indicative of the absolute concentrations of the first category of elements in the rock matrix, for irradiating the formation with a pulse of high energy neutrons and for detecting a second signal indicative of the relative concentrations of a second category of elements in a rock matrix. The absolute and relative concentrations of a plurality of elements are determined, and this information is used to transform at least one of the relative concentrations into an absolute concentration. One of the measured absolute concentrations is for aluminum, from which correlations are used to determine the absolute concentrations of other, non-measured elements. A tool system for measuring the absolute aluminum concentration includes a californium-252 source and a gamma ray detector having a plurality of windows from which the aluminum count rate can be compensated for interference by manganese activation.

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: Logging means and methods are disclosed for distinguishing between dispersed and laminated clay in earth formations. A wireline apparatus is employed consisting of a multifrequency induced polarization logging tool operating at extremely low frequencies, combined with other logging tools which measure the total amount of clay in the formation. A determination is then made of the fraction of the total clay content in the formation which is due to laminated clay.

Abstract: This system comprises means for standardizing the detected gamma spectrum and processing it by a reference spectrum. The lithology and/or the nature of the ores are determined, by a processing means, by comparison between the standard recorded spectrum and lithology and/or ore spectrum models contained in a library. The ore content, density and porosity can also be determined without supplementary measurements on the basis of the lithology and the nature of the ores.

Abstract: A computer-based system and method for acquisition of nuclear well logging data, including downhole generation of energy and time spectral information. For acquiring energy spectrum data, a downhole multi-parameter analyzer is provided including a pulse height analyzer and memory. The analyzer converts each gamma ray pulse height into a digital code by peak detection, level and pulse pile-up discrimination, sample-and-hold, and analog-digital conversion. The digital code includes the address of a unique memory location or channel corresponding to the energy of the particular gamma ray. After a preselected time interval the memory channels collectively contain counts for each incremental energy band in the desired energy spectrum. The memory may then be interrogated by the downhole CPU for presentation of a gamma ray emission versus energy level plot. For acquiring temporal spectrum data, the multi-parameter analyzer also includes a memory address generator.

Abstract: All natural water sources are "labeled" by a unique ratio of strontium isotopes (.sup.87 Sr/.sup.86 Sr). In accordance with the invention, the strontium isotope ratio for oil bearing formation water and for seawater which is to be injected into the formation is determined. The strontium isotope ratio of the produced water is then monitored at regular intervals and, when the strontium isotope ratio changes to that of the injected water, water injection breakthrough is delimited. The strontium isotope ratio thus serves as a natural tracer for seawater injection.

Abstract: Methods are disclosed which provide for quantifying and characterizing the mineral content of a formation as a function of depth. Elemental data derived from logging tools are input into an element-mineral transform operation, to determine the quantity of at least one or more dominant minerals in the formation including minerals distinguishable by degree of crystallinity. From the mineral quantity information and the elemental log data, the formation minerals are further characterized. Information regarding the character and quantities of formation minerals is further used to obtain improved determinations of formation characteristics such as the cation exchange capacity and water saturation, and the grain density and formation porosity, as well as to obtain an increased understanding of the formation such as the depositional environment of the formation.

Abstract: A method and apparatus (108) are disclosed for spectral gamma ray logging of a well borehole (106) to determine elemental concentrations of radioactive materials in subsurface earth formations (100) and in the borehole region. Anomalous radioactive deposition in the borehole region is identified and the effect thereof compensated for in the elemental concentration determinations.

Abstract: Methods are disclosed which provide for quantifying and characterizing the mineral content of a formation as a function of depth. Elemental data derived from logging tools are input into an element-mineral transform operation, preferably a matrix which is constructed using multivariate statistical analysis on previously available data, to determine the quantity of at least one or more dominant minerals in the formation. From the mineral quantity information and the elemental log data, the formation minerals are further characterized. Information regarding the character and quantities of formation minerals is further used to obtain improved determinations of formation characteristics such as the cation exchange capacity and water saturation, and the grain density and formation porosity, as well as to obtain an increased understanding of the formation such as the depositional environment of the formation.

Abstract: An apparatus and method are disclosed for determining the steam quality of a steam-water mixture prior to passage of the mixture from a steam injection well into steam-floodable formations located adjacent the well. The apparatus which may be lowered down into a steam injection well comprises a radiation emitting source located a selected distance away from a radiation detecting source. The steam-water mixture passes between the emitter and the detector. In operation an increase in the water content of the mixture causes attenuation of the radiation received by the detector. The decrease in the radiation received by the detector decreases the output signal of the detector. Corresponding signal changes as the steam quality of the mixture varies may be studied to determine the existing downhole steam quality at a particular location in the well.

Abstract: A method of measuring earth formation characteristics using a pulsed neutron source computes the characteristics by using a cumulative count curve. A pulsed neutron source and detector are pulled upwardly through a borehole. The pulsed neutron source repetitively irradiates the earth formations with pulses of fast neutrons from the neutron source, creating thermal neutrons due to collisions in the formations. Detectors in the downhole instrument detect gamma rays emanating from the irradiated formations as a result of the capture of thermal neutrons. The gamma rays are cumulatively counted in a plurality of separate time bins between each of neutron pulses. The cumulative counts define points on a cumulative count versus time curve which has a mathematical expression. Count data is transmitted to a surface panel, which uses iterative least squares fit techniques to calculate the formation lifetime decay constant.

Abstract: Well logging techniques are disclosed which use and/or measure formation textural parameters. A disclosed formation textural model is bimodal in nature, and includes fractions of spherical grains and of platey grains having a single aspect ratio. This model is used in obtaining improved well logging recordings.

Abstract: Statistical variations in simultaneous shallow and deep investigation nuclear borehole logs are reduced using digital moving average data processing while maintaining responsiveness to formation changes, by transitioning through a combination of long and short filtered data as a function of the statistical variation of the deep log data differences of the long and short derived averages. Borehole rugosity is also indicated as a function of the difference between the shallow and the deep log indexes of the differences between their respective narrow and wide derived averages.

Abstract: Uranium ore zones are quantitatively evaluated using the relative photoelectric absorption of naturally occurring gamma rays in two energy bands. One band experiences significant photoelectric absorption from uranium; the other does not. The ratio of the resultant measurements provides a quantitative indication of the uranium concentration.

Abstract: The uranium and thorium count rates from a fluid bearing shaly sand reservoir are normalized to the formation porosity and then, by a direct correlation, used to obtain the clay counter-ion concentration of the formation.

Abstract: A method and apparatus are described for logging an open hole well, or the like, for the purpose of determining the presence of a given constituent in the various substrata and for providing means and method for determining the degree of presence of the constituent in a given formation where it has been located. A probe capable of being lowered into a bore hole includes a color video camera, a particular form of light source, apparatus for carrying and issuing a spray of cleaning substance and apparatus for carrying and issuing a chemical which facilitates the analysis of the degree of presence of the constituent. The probe is lowered to the bottom of the bore hole and then raised to a desired level. A cleaning jet sprays the surface to be inspected. The cleaned surface is then illustrated with light having a frequency in a predetermined frequency range and the reflected light is directed to the camera. The video signal is conducted to the surface where it is displayed.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inelastic scattering and capture of neutrons from said neutron source. The spectra so generated may be analyzed and processed to derive parameters indicative of formation and borehole conditions, for example, a parameter sensitive to borehole geometry and a parameter sensitive to porosity. Certain parameters may be compared as an indication of the presence of gas in a fluid filled formation. Still further, a quantitative measure of the repeatability of the macroscopic thermal neutron absorption capture cross-section may be derived and used to control the weight of the capture cross-section filter.

Abstract: Compensation of photoelectric absorption measurements for borehole effects during nuclear logging of downhole earth formations is accomplished by detecting low energy gamma radiations entering two detectors in the logging tool along paths having substantially constant formation components but varying borehole components.

Abstract: A method for determining in situ the carbon content of a source rock comprises determining the carbon/oxygen elemental ratio of the formation via inelastic gamma spectroscopy, determining the porosity of the formation, obtaining the oxygen contents and densities of the fluid and minerals in said formation, and determining the carbon content from said carbon/oxygen ratio, and said oxygen contents and densities of the fluid and minerals. The density of the fluid may be assumed, as may the oxygen content of both the formation fluid and minerals. The mineral density may also be assigned a constant value based on lithology. An alternative total carbon content determination is made by additionally determining the fractional volume, density, and oxygen content of the organic matter in the formation, and the combined mineral-organic matter density, and combining this additional information with the previously-listed determinations.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data, including downhole generation of spectral information. A downhole instrument traverses a borehole introducing high energy neutrons into the formation at prescribed depths. Resultant gamma rays are detected and converted into pulses which are amplified and conditioned. For acquiring temporal spectral data, a multi-channel scale section is provided which includes a channel number generator which produces a numerical sequence of memory address codes corresponding to a sequence of adjacent time windows. Each code uniquely defines a start time, whereby the windows collectively comprise the time interval of the desired spectrum. Each time a gamma ray pulse is detected, the memory address generated at that time addresses a corresponding memory location and increments the count value resident therein.

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.

Abstract: A well logging sonde is disclosed which includes a collimating window design for the accurate detection of gamma rays of low and high energy which are back-scattered from a region near a source of gamma rays emitted into the formation. The sonde includes a tungsten support inner tube or shell surrounded by a length of "U" shaped steel. A conduit is formed in the wall of the shell at an angle with respect to its axis and is oriented symmetrically toward the opening of the "U" shaped steel support member. A closing member of a thin layer of titanium is welded to the open ends of the "U" shaped steel member. An arcuate tungsten pad is secured about the titanium closing member and partially about the exterior of the open ends of the "U" shaped steel support member. A conduit in the pad is aligned with the conduit of the inner shell to form a collimating window. A gamma ray detector of a length shorter than the "U" shaped steel section is mounted within the inner tube in the path of the collimating window.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inelastic scattering and capture of neutrons from said neutron source. The spectra so generated may be analyzed and processed to derive parameters indicative of formation and borehole conditions, for example, a parameter sensitive to borehole geometry and a parameter sensitive to porosity. Certain parameters may be compared as an indication of the presence of gas in a fluid filled formation. Still further, a quantitative measure of the repeatability of the macroscopic thermal neutron absorption capture cross-section may be derived and used to control the weight of the capture cross-section filter.

Abstract: Multi-phase fluid saturation in a sample of a porous media is determined through computed tomographic scanning. The sample is scanned with X-rays of differing energies in both the fluid saturated and fluid-extracted states. Each of the extracted fluids is also scanned at differing X-ray energies. The computed tomographic images produced are utilized in the determination of the X-ray mass attenuation coefficients for the sample and the extracted fluids. From these mass attenuation coefficients, the weight fractions and volume fractions of each of the extracted fluids are determined.

Abstract: A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inelastic scattering and capture of neutrons from said neutron source. The spectra so generated may be analyzed and processed to derive parameters indicative of formation and borehole conditions, for example, a parameter sensitive to borehole geometry and a parameter sensitive to porosity. Certain parameters may be compared as an indication of the presence of gas in a fluid filled formation. Still further, a quantitative measure of the repeatability of the macroscopic thermal neutron absorption capture cross-section may be derived and used to control the weight of the capture cross-section filter.

Abstract: A method for monitoring the movement of injected gas in an oil bearing formation behind the well casing is disclosed. A compensation neutron log is obtained from the well. The count rates are normalized to delineate water zones, gas zones and shale zones. Near and far count rates are rescaled and used to provide a qualitative determination of the distance from the point of injection to the top of the displaced gas in the formation by an analysis of the separation of the near and far count rate curves.