Abstract: A well logging system includes a digital threshold crossing data generation system (TCDG System) disposed in a well tool, adapted to be disposed in a borehole, and a digital first motion detection (DFMD) software disposed in a memory of a well truck computer. The TCDG system generates a series of threshold crossings for each analog signal received from a receiver of the well tool, the threshold crossings including a plurality of threshold crossing events for each analog signal and representing compressed versions of digitized analog waveforms. The well logging truck computer receives the threshold crossing data from the TCDG system and executes the DFMD software. When the software is executed, a first set of compressional wave first arrival times are determined from a startup routine in the software using the threshold crossing data.

Abstract: In the preferred embodiment of the new and improved perforating apparantus that is described herein, a set of end closure members are cooperatively arranged to be inserted into the open ends of a length of typical piping and expanded radially outwardly into contact with the rough and irregular internal wall surface in each end of the pipe. Anchor members and sealing members are arranged on each and closure member for releasably securing and sealingly engaging these end closure members in the ends of the pipe when the end closure members are respectively expanded outwardly so that no machining operations are required to prepare the internal wall surfaces of the pipe before it can be employed as an expendable perforating carrier.

Abstract: A shock mounted recorder carrier for a drill stem testing string, adapted for placement in a borehole, includes offset inner and outer bodies for placement of recorders within the carrier and further includes an overpressure gauge protector for protecting a set of recording gauges disposed in the carrier from a well fluid pressure which is greater than a predetermined amount above annulus fluid pressure and a balance joint for providing an oppositely directed force on the recording gauges relative to a direction of flow of the well fluid within the carrier thereby preventing the well fluid pressure from "bottoming out" the shock mount on which the recording gauges are mounted.

Abstract: A valve in a tool may be opened and closed by sequential application of a first predetermined annulus pressure and a second predetermined annulus pressure. A first rupture disc ruptures when the first predetermined annulus pressure is applied to the well annulus thereby allowing such pressure to be applied against a surface of an operator and moving the mandrel. This moves a yoke connected to the valve, opening the valve. A second rupture disc ruptures when the second predetermined annulus pressure is applied to the well annulus thereby allowing such pressure to be applied against a surface of a collet mandrel, moving the collet mandrel in a direction opposite to the direction in which the operator mandrel originally moved. Since the collet mandrel is connected to the operator mandrel and to the yoke, movement of the collet mandrel in the opposite direction moves the operator mandrel and the yoke in the opposite direction, thereby closing the valve.

Abstract: An input stimulus provides a necessary input to a microprocessor implemented control system. An output signal from the control system may fire one or more perforating guns of a perforating apparatus or it may change the state of a valve in a well testing apparatus. The input stimuli may comprise a pressure pulse transmitted down a well annulus disposed between a tubing string and borehole casing, a pressure pulse transmitted internally down the tubing string, an output of a strain gauge for sensing the set down weight of a well tool disposed in the borehole, or an output of an inductive coupler connected to the well surface.

Abstract: A method of perforating includes lowering a perforator and attached pressure measurement gauge assembly into a wellbore on wireline until the gauge assembly touches a bottom of the wellbore. Continued lowering of the wireline into the wellbore produces a slack on the wireline, the slack allowing the perforator to disconnect from the gauge assembly. The perforator is pulled uphole until the perforator is within a predetermined distance from the gauge assembly. Further pulling of perforator uphole ceases. The perforator is ready to be detonated. When well fluid is produced from the formation, the gauge assembly, resting on the wellbore bottom, records the pressure of the well fluid flowing from the formation. The perforator is retrieved from the wellbore. When it is desired to retrieve the gauge assembly from the bottom of the wellbore, a retrieving assembly is lowered into the wellbore by either wireline or sandline, the retrieving assembly connecting to the gauge assembly.

Abstract: A crystal oscillator including a crystal element designed to oscillate at a given frequency when subjected to an exciting voltage, and mounted parallel to and on a base through at least a wad made of at least a thin wound wire. Advantageously, the wire is randomly wound and is electrically conductive. The wad is elongated and is disposed parallel to said crystal and to said base.

Abstract: A transmitter for an induction well logging tool, adapted to be disposed in the borehole of an oil well, develops an output signal for energizing the borehole formation which inherently consists of six separate signal components, the six components including four primary signal components which simultaneously energize the borehole formation inducing in the formation four primary eddy currents. These four primary eddy currents are detected by the array induction tool receiver, the received signals being used to determine the resistivity and conductivity of the borehole formation.

Abstract: A perforating gun contains charges which are rotatable between a stored position and a deployed position, the charges being connected to an enclosed carrier tube via a mechanical link retaining apparatus which is capable of bending but is incapable of stretching by any substantial distance. A primacord is held by said retaining apparatus firmly onto a top of each charge thereby preventing relative movement between the primacord and the charge when the charge is deploying between its stored position and its deployed position. A set of pullrods connect to each pivot of each charge. Thus, when an upward force is placed on the pullrods, an accompanying force is placed on the pivots of each charge. Since the retaining apparatus connects to the top of each charge and to the carrier, and since the retaining apparatus is incapable of stretching by any substantial distance, the accompanying force on the charge pivots creates a torque which rotates the charges between the stored position and the deployed position.

Abstract: Various charge phasing arrangements in a perforating gun include those uniquely associated with phasing solely along a 180 degree circumference of the perforating gun, for use in but not limited to deviated boreholes. One phasing arrangement comprises four rows of charges, four corresponding rows of recesses in the perforating gun carrier and four corresponding rows of holes in the loading tube, the recesses, holes and charges being constrained within a 180 degree circumference of the perforating gun. The two outermost rows have more recesses, more holes and more charges than do the two innermost rows, since more well fluid is interposed between the two outermost rows and the casing than is interposed between the two innermost rows and the casing of the borehole.

Abstract: A perforating gun includes a base strip having an angular cross section, the base strip being a single unitary structure and essentially comprising at least two longitudinally disposed surfaces, a first surface and a second surface, a first plurality of capsule charges being connected to the first surface and a second plurality of capsule charges being connected to the second surface and interleaved with the first plurality of capsule charges, thereby phasing the capsule charges in the perforating gun. Since the gun utilizes capsule charges, good penetration into the formation is achieved. Due to the cross sectional configuration of the base strip, the phased capsule charges, when mounted on the strip, will easily fit within a tubing string previously used by non-phased capsule charge perforating guns.

Abstract: A method for obtaining samples of connate fluids from formations traversed by a borehole, wherein a sample test chamber is brought in communication with an isolated portion of the borehole wall, and is opened so as to allow the connate fluids to fill the chamber, and wherein the connate fluids are filtered through porous material including particles of determined sizes. The particles are bound together so as to form a rigid porous member, and have an average diameter which is a multiple of the diameter of the formation particles. Filter includes sieved gravel/sand embedded in a thermosetting resin. Alternatively, the filter includes metal bound together by superficial melting or welding.

Abstract: A method for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising the steps of:moving a logging tool through the tubing/screen over the depth region of the gravel pack, said logging tool including a neutron source able to emit neutrons at such an energy that their interaction with a first set of atoms indicative of the gravel pack quality causes the production of gamma rays, and at least one gamma ray detector; andderiving a measurement of the number of gamma rays resulting from the interaction of said neutrons and said first set of atoms of the gravel pack material, and which are detected by said detector over a predetermined counting time interval.

Abstract: A borehole logging method for determining the porosity of a formation surrounding the borehole, comprising the steps of: irradiating the formation surrounding the borehole from a location within the borehole with a burst of neutrons, detecting at a near detector indications of the concentration of thermal neutrons following the burst of neutrons and generating near count rate signals as a function of time in response thereto, detecting at a far detector indications of the concentration of thermal neutrons following the burst of neutrons and generating far count rate signals as a function of time in response thereto, fitting a count rate model to the near count rate signals to determine a near impulse formation count rate amplitude, fitting a count rate model to said far count rate signals to determine a far impulse formation count rate amplitude, determining the ratio of the near and far count rate signals as a characteristic proportional to the porosity of the formation.

Abstract: The invention relates to a tool having a valve (3c, 4c) for closing the tubing (100) of a well into which the tool has been placed. The valve member (4c) is controlled by means of a traction cable (17) via a hydraulic mechanism having two piston-and-cylinder assemblies (4b, 5e, 45; 1g, 4a, 41) which reduce the force applied on the valve member (4c) by the pressure of the fluid in the well and which amplify the force (f) applied thereto by the cable (17) in order to open said valve member.

Abstract: In order to take a practically unlimited number of fluid samples, in particular from a well in production, a sonde is used including as many modular sampling devices (10) as there are samples to be taken. These devices (10) are disposed end-to-end and they are actuated in succession by a central control rod (66 ) driven back-and-forth by an actuator device situated at the top end of the sonde. A bottom end piece puts the bottom sampling device into a ready position in which it is ready to be actuated by raising the rod (66). By taking a sample in this way, the bottom sampling device also serves to put the adjacent sampling device into its ready position, and so on all the way up to the topmost sampling device.

Abstract: The apparatus of the present invention relates to a down hole tool capable of extraction of valid samples and making pressure measurements useful in calculating formation permeability. The tool incorporates the features of a straddle packer to allow formation fluid specimens to be taken at large flow rates without depressing the pressure below the formation fluid bubble point. When used in combination with a pressure probe the tool is used to obtain meaningful permeability readings in a larger radius area than previously permitted with known designs. Additionally, the apparatus of the present invention allows flow control during the creation of the pressure pulse which enhances extraction of valid samples and the permeability determination.

Abstract: A nuclear spectroscopic method and apparatus for determining hydrocarbon saturation or water saturation of a formation adjacent a well bore is disclosed. Near and far inelastic gamma ray spectra are detected in response to pulses of fast neutrons irradiating the formation and materials in the borehole. Near and far carbon/oxygen (C/O) ratios are extracted from each spectra using predetermined spectra of postulated elements. The near and far C/O ratios are combined to determine a representation of formation hydrocarbon saturation substantially corrected for borehole gamma rays produced by inelastic reaction of fast neutrons and hydrocarbons in the well bore. Shielding of near and far detectors is provided to make the near detector more sensitive to gamma rays emanating from borehole gamma rays and to make the far detector less sensitive to borehole gamma rays and more sensitive to formation gamma rays.

Abstract: A novel neutron burst timing, detection, and calculation method and apparatus are disclosed for a Thermal Decay Time Logging System. A neutron bursting regime is provided which includes a short burst, long burst repetitive sequence. After a short delay from the short burst, a first series of time gates is provided for accumulating gamma ray counts. After a relatively longer delay from the long burst, a second series of time gates is provided for accumulating gamma ray counts. The thermal neutron decay time constant .tau. and the macroscopic capture cross-section .SIGMA. of the formation are determined through an iterative procedure by which the formation .tau. is estimated from the second series of time gates which have been stripped of borehole decay counts determined from the first series of time gates. Similarly, the borehole .tau. is estimated from the first series of time gates which have been stripped of formation decay counts determined from the second series of time gates.

Abstract: A piston of a well tool is disposed external to a tool housing, and within a space defined by an external sleeve and the housing, and pushes mud solids out of an open end of said space when the piston moves within the space of the tool. Due to the orientation of the tool within the borehole of an oil well, the open end of the space is subject to the force of gravity. Thus, when the piston moves downwardly within the space, mud solids disposed between the piston and the open end of said space are pushed out of the open end in response to the movement of the piston and the force of gravity.