Abstract: A method and device for measuring peak gamma radiation is provided wherein the method includes the steps of determining a minimum and maximum number of counts within a preselected multiple channel energy spectrum measurement range, determining a channel having approximately one-half the number of maximum counts, determining a channel representing a background energy, computing a peak energy centroid channel, computing a channel to energy conversion factor and recomputing the boundry channels for the preselected multiple channel energy spectrum measurement range.

Abstract: A method and apparatus are disclosed for acoustically investigating a borehole casing cement bond. A sonde is provided which is adapted to be lowered into a borehole and which includes a plurality of acoustic transducers arranged in a helical array around the sonde. A short duration acoustic pulse is directed at the borehole casing from each transducer and the reflection signal generated thereby is coupled to an autoregressive adaptive filter which automatically adjusts its filter coefficients to achieve a desired output signal. The adjusted filter coefficients are then utilized to determine the frequency and decay rate of the reflection signal and the frequency and decay rate of the reflection signal may be utilized to determine selected characteristics of the casing and the cement bond. In a preferred embodiment of the present invention, an additional transducer is mounted a selected distance from a fixed reflector to obtain standard transmission characteristics.

Abstract: A device and method for removal of debris from well bores coincident with introduction and placement of a bridge plug. The device comprises a hollow cylindrical body open at both ends. The lower end of the device is adapted to form a gauge ring, integral with the body of the device for cleaning or scraping of the well casing. The body of the device is penetrated by a plurality of openings of sufficient size to allow the passage of fluid while confining debris within the body of the device. The upper end of the device is adapted to be frangibly connected to the bottom of the bridge plug to be placed in the well casing. The method includes preparation of a well for production, wherein debris removal and bridge plug placement may be safely and economically performed in a single operation.

Abstract: Disclosed is a downhole logging and servicing system with manipulatable logging and servicing tools. The system includes a conveyor for running the tools into and out of the well bore and a manipulating apparatus operable responsive to fluid pressure to manipulate the tools. The manipulating apparatus includes a fluid operated incremental rotating device connected to the conveyor and control device operated by the rotating device to manipulate the tools.

Abstract: A logging device is disclosed for utilization in the detection of low energy photons. The logging device includes a sonde suitable for insertion into a wellbore. An insulating storage vessel is disposed within the sonde and serves to insulate a photon detection device and its associated electronic circuitry. The insulating storage vessel is constructed utilizing an inner and outer cylindrical shell. Each shell is constructed utilizing a low thermal conductive metallic material such as stainless steel or titanium and each shell includes at least a portion constructed utilizing a low density material having a high photon transmission property wherein low energy photons may be detected by the photon detection device within the insulating storage vessel. In a preferred embodiment of the present invention, an aperture is provided in the sonde which includes a plug of low density, low atomic number material wherein low energy photons may penetrate the sonde.

Abstract: A method and apparatus are described for reducing "Groeningen" effect and other anomaly induced errors in resistivity measurements of an earth formation. Such errors are typically noted during resistivity measurements of an earth layer and are generally referred to as "Groeningen" effect or "casing" effect. A sonde having a plurality of voltage measuring electrodes and current emitting electrodes is provided and suspended in a borehold by means of a conductive cable. The sonde is attached to the conductive cable by means of a length of insulated cable and two reference electrodes are disposed above the sonde. A survey current and at least two focusing currents are emitted from the sonde at alternate times or on alternate frequencies and various voltages induced by each current are measured and utilized to calculate a corresponding set of transfer impedances for that current.

Abstract: A chemical cutting apparatus for use within a well bore is disclosed. The apparatus of the present invention includes a tubular casing adapted to be lowered into a well bore. The tubular casing contains an internal chamber containing a chemical cutting fluid. A remotely operated explosive charge pressurizes the chamber of chemical cutting fluid and simultaneously forces chemical cutting fluid out through a discharge passage and erects a plurality of slips which anchor the tubular casing within the well bore. After a cutting operation has taken place, pressure buildup within the tubular casing which occurs as a result of a clogged discharge passage may be vented or bled off by the selective opening of a second discharge passage, thus preventing undesired engagement of the anchor slips during removal of the apparatus. In a preferred embodiment of the present invention, an interlock is provided which prevents the opening of the second discharge passage prior to ignition of the explosive charge.

Abstract: A downhold chemical cutting process for cutting a target object within a well. A source of a gaseous chemical cutting agent comprising a nitrogen fluoride is introduced into the well adjacent the target object and employed in a cutting operation in which the nitrogen fluoride cutting agent is directed against the target to the cut. A gaseous cutting agent source such as a mixture of florine and nitrogen trifluoride may be employed. Alternatively a perfluoroammonium salt which decomposes upon heating to produce a mixture of florine and nitrogen fluoride may be employed. A cutting tool comprising pressure actuated anchoring means, pressure generating and chemical sections, and a cutting section having a downwardly extending nozzle. The nozzle is provided with a standoff sleeve to provide a desired distance between the target object to be cut within a well bore and the nozzle outlet.

Abstract: Discloses an improved tool and method for cutting material by expelling a jet stream of liquid chemical reactant into forceful flowing connection and chemical reaction with a designated area of the material. Applies a force to at least one mass of reactant to move the mass through at least one jet orifice into flowing connection with material to be cut. Improvement is provision of a double rupture membrane adapted to confine the reactant mass until force is applied.

Abstract: Disclosed is a side entry sub with tension release wireline cable clamp. The side entry sub includes a tubular member having a port for the passage of the wireline cable into the interior of the tubular member. A cable clamp holder is positioned on the tubular member adjacent the port. The cable clamp holder has an axially extending passage with a cable clamp mounted therein. The cable clamp includes two clamp parts that are adapted to grip the cable therebetween. The cable clamp parts are movable from a gripping position to a releasing position responsive to axial movement with respect to each other in the clamp holder passage.

Abstract: A cable elongation or relaxation measurement apparatus comprises an elongated beam having spaced apart clamp assemblies for forcibly clamping a section of cable under tension. One of the clamp assemblies is slidably mounted on a pair of parallel bearing rods secured to the beam and is centered between opposite ends of the rods by coil springs. The movable cable clamp assembly supports a dial indicator which is engageable with an adjustable fixed abutment member supported on the beam so that movement of the movable clamp assembly can be measured for a known change in load on the cable. The support beam includes a pair of spaced apart support roller assemblies each including an upstanding bracket supporting a first roller and a movable support plate supporting a second roller. The second roller may be moved relative to the first roller between a cable engaging and clamping position and a position which permits mounting and demounting the apparatus with respect to the cable.

Abstract: Method and apparatus for radiological investigation of subterranean multicomponent media such as borehole fluids, and subterranean earth formations. The formation under investigation or other medium is irradiated with penetrating radiation having a plurality of discrete energy levels. The radiation at the several energy levels may be applied simultaneously or sequentially. In either case, the absorption of the applied radiation within the medium under investigation varies from one energy level to another. Radiation emanating from the medium is detected for each of the discrete energy levels and the intensity of the detected radiation for each energy level is correlated with the intensity of the applied radiation for each of the energy levels.

Abstract: A method and apparatus for measuring the differential or gradient of an earth variable within a well bore (e.g., the spontaneous earth potential) and producing improved logs of this gradient or differential and its integral variable essentially free of any accumulated instrument and base line drift or error. The differential spontaneous potential of an earth formation traversed by a well bore is measured at repeated multiple depths by moving a pair of closely spaced electrodes through the well bore wherein each electrode is electrically insulated externally from the other and from a third downhole local ground (such as the well tool cable) to which each is internally resistively referenced.

Abstract: A side-entry sub for use in conjunction with wireline cable. The sub has a cable entry port provided with a self-closing valve for sealing the port upon withdrawal of the cable. In one embodiment, the self-closing valve is characterized by a housing member supporting a closure disc which is integrally molded with a resiliently deflectable support member having an elastic memory which biases the valve in the closed position. In an alternate embodiment, the self-closing valve comprises a ball valve, biased in the closed position by magnetic or spring means, and having a passageway through which the cable may pass. When the cable is inserted through the passageway, the ball valve is held in the valve open position. When the cable is removed from the passageway, the ball valve automatically closes.

Abstract: A method of determining the porosity of earth formations surrounding a wellbore despite shielding of that formation by well casing, cement or mud cake. The method includes producing fast neutrons in a wellbore and detecting a first epithermal neutron population resulting from passage of neutrons from the source through a designated first region and a second epithermal neutron population resulting from passage of neutrons through a designated second region. The relationship of the logarithms of a first and a second epithermal neutron population resulting from passage of neutrons through a plurality of known porosity homogenous mediums is determined and plotted as a first curve with each point representing a unique value of porosity. A second curve of the logarithms of the first and second epithermal neutron populations in the actual wellbore is plotted.

Abstract: A method of well logging in petroleum exploration and apparatus for use in the method as described. An improved magnetometer is disposed in a well bore to provide indications of the distribution, filimentation, and distortion of a controlled current flow within adjoining strata of interest. The current flow is excited by a distant alternating source located at the surface or at other boreholes, and perturbations in the current flow and accompanying magnetic field caused by the electrical characteristics of the adjoining strata are registered by the magnetometer.The magnetometer comprises a pair of elongated U-shaped cores of laminated, high-permeability metal, with portions of each core being surrounded by a sensing coil. The coil output is fed to surface equipment for detection and analysis.

Abstract: A downhole chemical cutting tool having an improved cutting section. The tool comprises an elongated tool body adapted for insertion into a well bore and includes anchoring means actuatable between a deployed position in response to the application of fluid pressure and a retracted position in response to the release of such pressure. The tool further includes a chemical section and a cutting section located in front of the chemical section. The cutting section has a longitudinally extending bore which is in fluid communication with the chemical section at the rear of the cutting section and in fluid communication with the exterior of the tool body at the front of the cutting section. The cutting section is provided with one or more cutting ports through which the cutting fluid passes when the tool is fired. A piston is slidably disposed in the bore of the cutting section at a location between the ports and the chemical section.

Abstract: A bridge plug for use in plugging a well at a subterranean location and adapted to be set in place by insertion through a tubing string. The bridge plug comprises an elongated vent tube supporting upper and lower petal basket structures, each of which comprises a plurality of petal leaves movable between a retracted position and an expanded position. In the expanded positions the petal leaves for the upper and lower baskets form conical configurations which face upwardly and downwardly respectively. Upper and lower fabric bags cover the respective petal basket structures respectively and extend over the inner and outer surfaces of the petal leaves. Each of the petal basket structures are further provided with conically shaped liners formed of an impermeable material inside the bags and interposed between the inner surfaces of the petal leaves and the conforming portions of the bags. The liners may be formed of an adhesion-resistant material such as fiber-glass fabric coated with a polytetrafluoroethylene.

Abstract: A method and apparatus for remotely attaching one object to another object comprising: (a) a target consisting of layers of contrasting hardness attached to one object, wherein the outer layer is a relatively soft composition and the underlying base is a relatively hard composition, and (b) a projectile of intermediate hardness attached to the other object. By propelling the projectile against the target, the projectile penetrates the softer outer layer and expands upon impact with the inner layer, thus securely anchoring the two objects together. Such a method and apparatus are useful in outer space and underwater applications.

Abstract: A well tool positioner is adapted for positioning the tool in a desired relation within a well pipe. The positioner includes a generally cylindrical resilient body adapted to be closely mounted around a tool with the major outside diameter of the body being substantially no larger than the outside diameter of the tool. At least three support vanes are formed with the body as an integral member with each vane being generally ellipsoidal in cross-section and extending perpendicular from the axis of the body and with the major axis of the generally ellipsoidal shape extending along the axis of the body. The body defines an exterior annular recess in the vicinity of the support vanes such that the recess provides an increase in effective flow area between the body and the outer tips of the vanes which at least partially compensates for the decrease of such flow area as caused by the total thickness of the vanes.