Abstract: One embodiment includes an apparatus that includes a coherent radiation source to emit coherent radiation through a signal carrier that is positioned along at least a part of a length of a downhole drilling component. The apparatus also includes a receiver to receive the coherent radiation that is to be emitted through the signal carrier.

Abstract: A system for handling a radioactive source includes a container containing a radioactive source and a cap mounted on the container to retain the radioactive source inside the container. The cap has a first locking structure and a second locking structure. The system further includes a handling tool having a support shaft, a first locking tip adapted to form a first lock with the first locking structure, and a second locking tip adapted to form a second lock with the second locking structure. The first and second locking tips are slidably coupled to the support shaft.

Abstract: The present generally relates to apparatus and methods for instrumentation associated with a downhole deployment valve or a separate instrumentation sub. In one aspect, a DDV in a casing string is closed in order to isolate an upper section of a wellbore from a lower section. Thereafter, a pressure differential above and below the closed valve is measured by downhole instrumentation to facilitate the opening of the valve. In another aspect, the instrumentation in the DDV includes sensors placed above and below a flapper portion of the valve. The pressure differential is communicated to the surface of the well for use in determining what amount of pressurization is needed in the upper portion to safely and effectively open the valve. Additionally, instrumentation associated with the DDV can include pressure, temperature, seismic, acoustic, and proximity sensors to facilitate the use of not only the DDV but also telemetry tools.

Abstract: The present invention describes a unique method and apparatus for applying near-infrared spectroscopy to estimate weight percent of methane in crude oil from which one can then infer gas-oil ratio (GOR) of crude oils downhole in real time while collecting a fluid sample. The correlation equations provided by this invention use two wavelengths, one centered at 1670 and the other centered at 1682 nm. Both wavelengths are primarily sensitive to the methane peak absorption. To significantly improve the fit, non-spectroscopic parameters, such as temperature or pressure, can be included in the correlation equation. Also, this invention can be used to monitor sample cleanup by monitoring the increase in GOR associated with cleanup as a fluid being pumped from the formation transitions from mostly gas-free filtrate to mostly gas-containing crude oil.

Abstract: A system for measuring elemental compositions and other properties of earth formation penetrated by a borehole, wherein the measurements are made while drilling the borehole. The downhole instrumentation includes a neutron source and a gamma ray detector disposed in a drill collar. Formation parameters of interest are determined from the energy and intensity of gamma radiation induced in the formation by the neutron source. By minimizing the amount of iron in the immediate vicinity of the gamma ray detector, disposing no iron directly between the detector and the formation, and positioning the gamma ray detector as close as practical to the formation, interfering gamma radiation from iron is reduced thereby increasing precision and accuracy of the formation parameter measurements.

Abstract: We disclose density measurement methods that are accurate over an extended range of standoff distances. One method embodiment includes: a) obtaining a standoff distance, a near detector count rate, and a far detector count rate; b) determining a formation density measurement using near and far detector count rates when the standoff distance is less than a predetermined value; and c) determining the formation density measurement using just the far detector count rate and the standoff distance measurement when the standoff distance is greater than the predetermined value. The method may further include calculating a calibration parameter when the standoff distance is less than the predetermined value. The calibration parameter serves to calibrate a standoff-based correction to the far detector count rate, enabling accurate formation density measurements at large standoff distances. The measurements are made with a rotating logging tool, causing the standoff distance to cycle between large and small values.

Abstract: A tool is presented for making density measurements of a formation surrounding a wellbore, comprising a collar housing in a drill string. The housing has at least one first section with a first outer diameter, and at least one sensing section with a second outer diameter located proximate the at least one first section. The second outer diameter is smaller than the first outer diameter. A radioactive source is disposed in the sensing section of the housing. At least two detectors are disposed in the sensing section and spaced from the radioactive source and are positioned to detect radiation resulting from gamma rays emitted by the source.

Abstract: A drill bit, comprising a bit body, a sensor disposed in the bit body, a single journal removably mounted to the bit body, and a roller cone rotatably mounted to the single journal.

Abstract: A system for measuring elemental compositions and other properties of earth formation penetrated by a borehole, wherein the measurements are made while drilling the borehole. The downhole instrumentation includes a neutron source and a gamma ray detector disposed in a drill collar. Formation parameters of interest are determined from the energy and intensity of gamma radiation induced in the formation by the neutron source. By minimizing the amount of iron in the immediate vicinity of the gamma ray detector, disposing no iron directly between the detector and the formation, and positioning the gamma ray detector as close as practical to the formation, interfering gamma radiation from iron is reduced thereby increasing precision and accuracy of the formation parameter measurements.

Abstract: Logging-while-drilling gamma ray back scatter density system with elements configured to minimize material between sensor and the borehole environs, maximize shielding and collimation efficiency, and increase operational reliability and ruggedness. The system comprises a drill collar with a cavity in the outer wall, and an instrument package containing a sensor. The instrument package is disposed in the cavity and protrudes from the outer wall of the collar. Embodied as a density LWD system, the sensor consists of a gamma ray source and two detectors mounted within an instrument package framework made of high Z shielding material. A stabilized containing an alignment channel in the inner surface is disposed around the collar and receives the protrusion. The source and detectors are preferably positioned within the instrument package so that they fall within a radius defined by the outer surface of the collar. The source is threaded directly into the high Z material framework of the instrument package.

Abstract: A method is disclosed for determining a characteristic of a mud mixture surrounding a drilling tool within a borehole in which a drilling tool is received. The method includes turning the tool in the borehole. Energy is applied into the borehole from an energy source disposed in the tool. Measurement signals are received at a sensor disposed in the tool from a location around the borehole. The cross-section of the borehole is separated into at least a first sector and a second sector. A first measurement signal from the first sector is substantially in response to returning energy which results from the interaction of the applied energy with the mud mixture. A second measurement signal from the second sector is substantially in response to returning energy which results from the interaction of the applied energy with the formation. An indication of an intrinsic characteristic of the mud mixture is derived from the first measurement signals associated with the first sector of the borehole.

Abstract: A method for measuring one or more characteristics of an earth formation whereby energy is emitted circumferentially about a borehole into the formation, and the amount reflected back is detected during a plurality of sample periods. The samples are grouped into two or more groups by the azimuthal sector in which the sample was collected. Within a group, each sample is mathematically weighted according to the standoff of the detector from the borehole wall when the sample was taken. Within a group, the weighted samples are summed to produce a weighted total amount of energy detected within a sector. The weighted total is then transformed into the one or more characteristics.

Abstract: A method for determining which of a plurality of detectors transmitted a signal, such as a signal related to neutron or gamma emissions, includes connecting each of the detectors to a single cable, such as an environmentally rugged cable. Signals are transmitted from each of the detectors over the single cable. The two ends of the cable are connected to two receivers. A different unique delay is introduced between receipt by the two receivers of a signal over the cable for each of the detectors. The receivers, which have a preamplifier, an amplifier and a discriminator, receive the signals from the two ends of the cable. A timing analyzer, such as a time-to-amplitude converter, measures a delay between one signal from one end and the other signal from the other end of the cable. A processor employs the amplitude of the signal output by the timing analyzer.

Abstract: A novel method, system and tool for performing formation and well evaluation while drilling are disclosed. These inventions determine the properties of a particular formation within a reservoir as the reservoir is being intersected during well construction. In one form of the invention, the formation evaluation is made using a direct measurement of the formation's ability to flow fluids. The flow potential of a reservoir during underbalanced well construction is determined as the well is being constructed. The methods produce an understanding of the volumes and types of fluids such as oil, gas, and/or water, that can be produced out of discrete sections of a formation within a reservoir as the reservoir is intersected.

Abstract: Interpolymers of 1-99 mol % vinyl fluoride and 99-1 mol % of at least one highly fluorinated monomer such as tetrafluoroethylene are disclosed. The interpolymers are characterized by the presence of ionic end groups and are prepared by polymerizing VF and fluorinated monomer in water with water-soluble free-radical initiators such as azoamidine initiators or persulfate initiators at temperatures within the range of 60 to 100° C. and reactor pressures within the range of 1 to 12 MPa (145 to 1760 psi). The invention firer provides for protective self-supporting films and coatings formed from nonaqueous dispersions of the interpolymers, both for use on the surfaces of substrates including metal, plastic, ceramic, glass, concrete, fabric and wood.

Abstract: A system is disclosed for compensating well logs for adverse effects of the borehole and near borehole formation effects. The system is configured primarily for processing logging-while-drilling (LWD) density measurements, and includes means for generating a one-dimensional density log which is corrected for adverse effects of logging tool standoff and “dipping” beds penetrated by the borehole. The system is, however, applicable to any type of LWD or other type of logging system which requires borehole corrections, and which responds to variations in formation properties in a plane perpendicular to the borehole. The system can also be modified to include LWD apparatus using sensors that require no borehole corrections, and only require corrections for dipping beds. The system is ideally suited for logging equipment using two sensors, but can be modified for use with single sensor systems or systems using more than two sensors.

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: An optic sensor for use in a well is provided. The sensor can be configured to sense downhole conditions, such as temperature, pressure, or stress, either individually or in combination. The optic sensor has a sensor housing that defines a chamber. The sensor housing also defines a region that is responsive to an external force. An optic fiber extends through the housing. The optic fiber has a dielectric boundary that resides within the housing chamber , and has a refractive index variation that provides maximum reflectivity at a central reflectivity wavelength, the central reflectivity wavelength correspondingly shifting with respect to an expansion or contraction of the region. In a further aspect of the invention, the optic fiber has a second dielectric boundary spaced apart from the first dielectric boundary.

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 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 well logging instrument and method that remove vibration induced noise from the output of a detector including a scintillation crystal. The invention is based on a realization that pulses induced by vibration during MWD operations are characteristically periodic, whereas pulses generated down hole by gamma rays occur at random intervals and are characteristically non-periodic. The instrument and method involve positioning a scintillation crystal package in the high vibration environment for interaction with incident radiation, using a light sensing device to convert photons received from the scintillation crystal package into an electrical signal which over time is composed of radiation induced events that are non-periodic and vibration induced events that are periodic, distinguishing the periodic events using a time history of the electrical signal, and removing the periodic events from the electrical signal to provide a corrected electrical signal from which vibration induced components have been removed.

Abstract: A method and apparatus is disclosed for suppressing microphonic noise in proportional counter neutron detection in borehole logging-while-drilling measurements. Noise is reduced by (1) applying the outputs of two detectors respectively to positive and negative inputs of a differential amplifier; (2) generating output pulses by applying the output of the differential amplifier to positive and negative comparators to produce first and second output pulses; (3) counting output pulses as neutron counts only if the first or second output pulses have time lengths less than a predetermined time length; and (4) rejecting the output pulses in the count of pulses as neutron counts if first and second output pulses coincide in time.

Abstract: A logging-while-drilling apparatus includes a source of exciting radiation, means for illuminating the borehole wall with the radiation and means for detecting radiation returning from the borehole resulting from illumination with the exciting radiation. A bottom hole assembly (BHA) incorporating such apparatus can comprise a drill bit, one or more stabilizers and one or more drill collars and the source and illuminating and detecting means can be located in one of these or distributed therebetween according to requirements. A window can be provided to allow illumination of the borehole and detection of returning radiation.

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 method and apparatus is disclosed for distinguishing gamma ray induced pulses from shock induced pulses of a scintillation detector used in logging while drilling tools. The method and apparatus identifies detector pulses which occur within a predetermined time interval from a previous pulse as shock induced pulses and identifies pulses that occur after a predetermined time interval from a previous pulse as gamma ray induced pulses.

Abstract: Earth formation evaluation for detection of hydrocarbon fluids is carried out by a microwave frequency range sensor (antenna or wave guide) disposed in the face of a diamond or PDC drill bit configured to minimize invasion of drilling fluid into the formation ahead of the bit. The sensor is connected to an instrument disposed in a sub interposed in the drill stem for generating and measuring the alteration of microwave energy. In particular, the dielectric constant of the earth formation in a zone which is substantially uninvaded by drilling fluid may be detected and compared with density and/or porosity logs to determine the presence of hydrocarbons in relatively thin layers of formation material.

Abstract: A method and apparatus for measuring formation characteristics as a function of angular distance segments about the borehole is disclosed. The measurement apparatus includes a logging while drilling tool which turns in the borehole while drilling. Such characteristics as bulk density, photoelectric effect (PEF), neutron porosity and ultrasonic standoff are all measured as a function of such angular distance segments where one of such segments is defined to include that portion of a "down" or earth's gravity vector which is in a radial cross sectional plane of the tool. The measurement is accomplished with either a generally cylindrical tool which generally touches a down or bottom portion of the borehole while the tool rotates in an inclined borehole or with a tool centered by stabilizer blades in the borehole.

Abstract: A modular measurement while drilling sensor assembly is presented. A typical cross-over assembly for mating with a measurement while drilling (MWD) tool is connected to a typical positive displacement mud motor (e.g., a Moineau motor). A modular sensor assembly comprises two portions, an upper drive shaft portion which includes a flexible shaft connected to the motor and a lower sensor portion and supported by a radial bearing. The lower end of the flexible shaft is connected to a hollowed shaft which extends beyond the lower end of the upper drive shaft portion and which is supported by a radial bearing. The lower sensor portion has a central channel extending longitudinally therethrough, with the lower portion of the hollowed shaft extending through this channel. The sensor portion may comprise any type of MWD sensor, however the present invention is preferably used with sensors (e.g., formation evaluation sensors) that benefit from obtaining measurements close to the bit.

Abstract: A method and apparatus for determining at least one characteristic of a formation is provided which includes storing a plurality of counts received from both a long space radiation detector and a short space radiation detector. The counts are detected during a plurality of short duration time periods which are brief compared to rotary drilling speed. A count rate mean is determined and used to sort each of the plurality of count measurements into one of at least three bins. Count information accumulated in at least one of the bins is used to calculate a corrected density. A short space collimator enhances the count rate of singly scattered gamma rays detected by the short space detector and blocks gamma rays from the formation radially outwardly of the short space detector to improve spine-rib correction characteristics for relatively short standoffs. The method of sorting the plurality of short duration time period measurements improves the accuracy for short standoffs to larger standoffs.

Abstract: A method for analyzing data from a measurement-while-drilling (MWD) formation evaluation logging tool which compensates for rotation of the logging tool (along with the rest of the drillstring) during measurement periods. The density measurement is combined with the measurement from a borehole caliper, preferably an acoustic caliper. The acoustic caliper can continuously measure the standoff as the tool is rotating around the borehole. If the caliper is aligned with the density source and detectors, it can determine the standoff in front of the detectors at any given time. This information can be used to separate the density data into a number of bins based on the amount of standoff. After a pre-set time interval, the density measurement can then be made. The first step in this process is for short space and long space densities to be calculated from the data in each bin. Then, these density measurements can be combined in a manner that minimizes the total error in the density calculation.

Abstract: The method comprises using a transmitting unit and at least two receiving units (8,10) arranged in two different places along well equipment (2). Each receiving unit forms an image or signature of wall portions which pass it. The signatures of wall portions formed by the lower receiving unit (8) when the well equipment is being lowered into the well are stored and the upper receiving unit (10) stores signatures coming from the wall portions which were previously stored by the lower receiving unit. A comparison (for example a correlation) of the signatures respectively coming from the two receiving units allows a common wall portion which has produced two substantially identical compared signatures to be identified. The time interval between the formation of the two substantially identical signatures is measured and the rate of penetration is calculated. As application of the invention is for the measurement of the true rate of penetration of a well tool or of a measuring sonde.

Abstract: Method and apparatus for fishing for and/or communicating with subsurface apparatus. In a preferred embodiment, a subsurface logging-while-drilling (LWD) or measuring-while-drilling (MWD) apparatus is placed in tandem with a drill string near the bottom of a borehole. The LWD apparatus includes a surface retrievable component such as a nuclear source carrier with a fishing head facing upwardly. The carrier is releasably secured within the LWD apparatus with means such as a shear pin. A wireline conveyed tool having a downwardly facing latching mechanism includes a downhole powered latch for telescopically extending beyond the fishing head, forcing a latching lug radially inwardly below the fishing head, and moving axially upward to latch the fishing head. Further upward latch movement causes the fishing head to move upwardly until the shear pin shears which releases the carrier from the subsurface apparatus. The wireline tool with the attached carrier is then brought to surface with the wireline cable.

Abstract: A downhole tool for use in measurement-while-drilling applications includes modular ring connectors on opposed ends thereof with the ring connectors being interconnected by a single bus for delivering both power and ground.

Abstract: Apparatus and method for measuring density, porosity and other formation characteristics while drilling is disclosed. The apparatus, preferably housed in a drill collar and placed within a drill string, includes a source of neutrons and a source of gamma rays placed within a tubular body which is adapted to provide for the flow of drilling through it. Two sets of stabilizer blades are provided. One set, associated with the neutron source, includes secondary radiation detectors that are placed radially beyond the nominal outer radius of the body. Formation porosity measurement accuracy is substantially enhanced since the standoff of the detectors from the formation is substantially decreased. Another set, associated with the gamma ray source, includes one or more gamma ray detection assemblies in a single blade. Each of the gamma ray detector assemblies is also placed radially beyond the nominal outer radius of the tubular wall.

Abstract: An apparatus for nuclear logging is presented. In accordance with the present invention, nuclear detectors and electronic components are all mounted in chambers within the sub wall with covers being removably attached to the chambers. A single bus for delivering both power and signals extends through the sub wall between either end of the tool. This bus terminates at a modular ring connector positioned on each tool end. This tool construction (including sub wall mounted sensors and electronics, single power and signal bus, and ring connectors) is also well suited for other formation evaluation tools used in measurement-while-drilling applications.

Abstract: A coring tool is lowered to the bottom of a wellbore through a subsurface formation. A coring bit at the lower end of the coring tool draws a core sample of the subsurface formation at the bottom of the wellbore into the coring tool. A coring barrel is positioned along the coring tool above and in juxtaposition with the coring bit. The core sample is drawn into a hollow cylindrical split member within the coring barrel, such member being split into two halves in an axial direction and comprised of a material effectively transparent to nuclear radiation. A wireline raises the split member containing the core sample upward through the coring tool to the surface of the earth. The core sample is tested for a nuclear radiation characteristic through the nuclear radiation transparent material of the split member at the well site. The split member is then reused to obtain a plurality of cores from the subsurface formation.

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: A method and apparatus for measuring the gamma radiation levels of drilling mud expelled from an oil and gas bore hole to determine the composition of the earth at the bottom of the bore hole and, when used in conjunction with a Measurement While Drilling gamma radiation detector, to determine the time and location of bore hole cavings. A first gamma radiation detector measures the gamma radiation level of the drilling mud with the bore hole entrained material, and a second gamma radiation detector measures the gamma radiation of the drilling mud without the entrained material. The difference between the two measurements is lagged to the time between the detectors and the bore hole bottom.

Abstract: An apparatus for nuclear logging is presented. In accordance with the present invention, nuclear detectors and electronic components are all mounted in chambers within the sub wall with covers being removably attached to the chambers. A single bus for delivering both power and signals extends through the sub wall between either end of the tool. This bus terminates at a modular ring connector positioned on each tool end. This tool construction (including sub wall mounted sensors and electronics, single power and signal bus, and ring connectors) is also well suited for other formation evaluation tools used in measurement-while-drilling applications.

Abstract: A measurement-while-drilling (MWD) density tool is provided which incorporates a single gamma ray source and a pair of longitudinally displaced and mutually aligned detector assemblies (i.e., dual scintillation counters). A nuclear source is mounted in a pocket in the sub wall and partially surrounded by gamma ray shielding. The subwall section adjacent the source is expanded radially so as to define a lobe which displaces mud thus reducing borehole and mudcake effects. The two detector assemblies are mounted within a cavity or hatch formed in the subwall and enclosed by a detector hatch cover under ambient pressure. The detector assemblies are fixedly spaced from the source and are also partially surrounded by gamma ray shielding to provide good formation response. The hatch cover is secured to the sub by bolts and contains radiation transparent windows therethrough in alignment with the detector assemblies. A threaded-on fluid displacement sleeve is positioned on the sub and over the detector hatch cover.

Abstract: A method and apparatus for nuclear logging is presented. In accordance with the present invention, a radioactive source is mounted within the sub wall in alignment with the radiation detectors and orthogonal to the longitudinal axis of the sub. In addition, a novel radioactive source container and insertion tool is disclosed.

Abstract: This invention relates to a method for analyzing data from a measurement-while-drilling (MWD) formation evaluation logging tool which compensates for rotations of the logging tool (along with the rest of the drillstring) during measurement periods. In accordance with this method, the received signal is broken down into a plurality of sections. In a preferred embodiment, the present invention calls for the breaking of the signal from the formation into four different sections: top, bottom, right, left. As the tool rotates, it will quickly pass through these four quadrants. Each time it passes a boundary, a counter is incremented, pointing to the next quadrant. This will allow for dividing the data into four spectra for each detector. Each of these four spectra will be obtained for 1/4th of the total acquisition time. The relative error is minimized by comparing the relative error in each spectrum and selecting a specific spectrum or by combining at least two spectra.

Abstract: Improved radioactivity well logging by mounting a scintillator and photomultiplier tube in a single case interfacing with a hole extending through a drill collar at the lower end of a drill string so that measurements can be made while drilling. Radioactive sources (when required for well logging) are mounted in cavities which open to the exterior of the drill collar. Light from the scintillator is coupled directly to the aligned photomultiplier tube both of which are mounted in a case extending radially within the drill collar and sealingly engaging an electronics housing within the drill collar and the drill collar wall surrounding the hole. The scintillator is of greater diameter than the photomultiplier tube. A frustoconical light pipe connects the scintillator and the photomultiplier tube, channeling scintillation in the crystal to the photomultiplier to provide an amplified detection capability over that for a scintillator having the same diameter as the photomultiplier tube.

Abstract: An analyzer includes a test cell which contains a core of coal from a coal bed methane reservoir. A tomographic system is used for testing the core at different times and provides signals corresponding to the tests. While the earthen core is being tested, a fluid having the same size molecules as methane is provided to the earthen core as part of the testing. The signals from the tomographic system are used to determine the methane storage capacity of the core.

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: 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: Improved radioactivity well logging by mounting a scintillator in a hole extending through a drill collar at the lower end of a drill string so that measurements can be made while drilling. Radioactive sources (when required for well logging) are mounted in cavities which open to the exterior of the drill collar. Light from the scintillator is coupled through a right-angle prism or fiber optics through an angle of about 90.degree. so that an elongated photomultiplier tube can be mounted within a housing within the drill collar with the longitudinal axis of the photomultiplier tube extending substantially parallel to the axis of the drill collar to provide maximum cross sectional area for flow of drilling fluid with the housing in the drill collar.

Abstract: Downhole measuring apparatus includes a gamma radiation source and at least two pairs of radiation detectors carried by a housing so that radiation may be emitted from the source and scattered by the environment of the housing and detected by the detectors. Each pair of detectors is arranged so that its detectors are positioned symmetrically on opposite sides of the longitudinal axis of the housing, and each pair of detectors, in combination with the radiation source, forms a different geometrical configuration so that, in general, the radiation counts obtained by the different pairs of detectors will not be redundant. The output signals from the detectors may be processed to provide data signals indicative of the radiation counts experienced by the detectors, and which may then be used to simultaneously obtain values for two or more downhole parameters. The addition of each new, independent pair of detectors permits the simultaneous solution of an additional downhole parameter.

Abstract: A method of calibrating a radiation detector, positioned in apparatus including a source of gamma radiation such that the detector may sense radiation from the environment of the apparatus due to radiation emitted by the source and scattered by the environment, includes utilizing test environments including formations of known bulk densities. The apparatus may be positioned within the test environments at different distances from the surfaces of the formations. Count rates of the detector are compared to the formation bulk densities for the distances of the apparatus from the formation surfaces to calibrate the detector relative to the radiation source.