Abstract: An improved well logging technique is provided for more accurately deriving acoustic measurements of subsurface earth formations. Method and apparatus are described for converting an acoustic signature which can be generated on a depth dependent or time dependent basis, into digital format and subsequently employing special processing techniques to yield parameters such as velocity of the transmitted acoustic energy through earth formations and the amplitude of the received acoustic energy. Processing further allows for the generation of noise immunity signals functionally related to a measured signature parameter and for the generation of amplitude control signals. Additionally, a control signal is generated to optimize transmitter firing rate.

Abstract: A pulsed source of fast neutrons and a radiation detector system are utilized in a well logging instrument, the detector being responsive to the thermal neutron population decay rate. The inverse of the decay rate is proportional to the measured macroscopic neutron absorption cross-section (Sigma). A Sigma is calculated by taking the natural logarithm of the ratio of the detected radiation counts occurring within two measurement intervals of fixed duration and starting at a fixed time after the neutron burst. This Sigma measurement provides a feedback voltage which is used in altering the starting time of a single measurement interval in a subsequent source pulsing cycle to provide a measured Sigma value.

Abstract: A pulsed source of fast neutrons and a radiation detector system are utilized in a well logging instrument, the detector being responsive to the thermal neutron population decay rate. The inverse of the decay rate is proportional to the measured macroscopic neutron absorption cross-section (Sigma) of the surrounding formations. A first Sigma is measured by taking the natural logarithm of the ratio of the detected radiation counts occurring within two measurement intervals. A second Sigma is measured by taking the natural logarithm of the ratio of the detected radiation counts occurring within a second pair of measurement intervals. The first Sigma value is recorded when the Sigma value falls below a preselected limit and the second Sigma value is recorded when the formation Sigma value is above the preselected limit. Thus, the Sigma log is a composite of the two Sigma measurements.

Abstract: A pulsed source of fast neutrons and a radiation detector system are utilized in a well logging instrument, the detector being responsive to the thermal neutron population decay rate. The inverse of the decay rate is proportional to the measured macroscopic neutron absorption cross-section (Sigma). A Sigma is calculated by taking the natural logarithm of the ratio of the detected radiation counts occurring within two measurement intervals of fixed duration and starting at a fixed time after the neutron burst. This Sigma measurement provides a feedback voltage which is used in altering the starting time of two measurement intervals in a subsequent source pulsing cycle to provide a measured sigma value.

Abstract: Improved methods and apparatus are provided for correlatively matching, recording, and displaying, two or more sets of logging data measurements with respect to the borehole depth at which they are generated, and independent of their historical or real-time character. In a particular embodiment of the invention, measurements from each set of data derived or sampled at correlative depths are adjacently displayed in graphical form during a logging operation. The depth offset between the measurements is visually or automatically detected, and in response thereto, the subsequent correlation of other selected measurements and depths at which subsequent measurements are derived are thereby adjusted for further processing, display and recording.

Abstract: A square wave clock signal is coupled to a transistor, the output of which is transformer coupled to the base of a driver transistor. The conducting of the driver transistor will cause an increase in the current through the primary of a flyback transformer, thereby resulting in a relatively small negative going voltage potential being induced therein. When the driver transistor is caused to go into a non-conducting state, due to the signal on the base, the decrease in current through the primary of the flyback transformer in relation to the change in time is large, thereby inducing a large positive voltage potential across the primary. The induced voltage is stepped-up by the flyback transformer where the negative overring portion is rectified and regulated to supply a potential to the grid of an ion source.

Abstract: Method and apparatus for reducing the dynamic range of measure signals encountered in simultaneously obtaining two focused logs of formation resistivity with different depths of investigation and means for providing the required electrical connections of the electrode system. The apparatus includes an electrode system having a central electrode, a near and far pair of current electrodes, respectively shortcircuited, and aligned symmetrically on both sides of the central electrode, and a near and far pair of measure electrodes, respectively shortcircuited, and aligned symmetrically between the central electrode and the near pair of current electrodes. A signal detected on the near measure electrode pair at a preselected frequency and a first and second signal are combined to produce first and second combined voltages which are used in the production of a first and second frequency, f.sub.1 and f.sub.2, respectively.

Abstract: An improved technique is provided for comparing the velocity of an elongated well logging instrument traversing an inclined earth borehole with the playout velocity of the well logging cable at the earth's surface to control both the cable hoist drum rotation and the rate of movement of the subsurface instrument and thus insure cable playout is in equilibrium with the logging instrument movement. Method and apparatus are described for detecting any reduction in movement of the logging instrument through the borehole and for reducing the velocity of the logging cable playout in response thereto by reducing drum rotation. Further, when the velocity of cable playout slows to a preselected value, a monitoring circuit generates control signals which actuate a means of power attached to or integral with the logging instrument which, upon initiation, apply a force to move the logging instrument upward or downward within the borehole.

Abstract: Gamma spectrum measurement signals received from a downhole instrument containing a scintillation counter are coupled into a multi-channel analyzer. The analyzer converts the received pulses to pulses in separate channels according to energy levels of the received measurements. The energy channels from the multi-channel analyzer are coupled to digital decoders which are set up for energy level windows for preselected elements and the total occurrence count. These outputs are coupled into a microprocessor stripper which includes storage buffers sized in accordance with the logging rate and crystal utilized in the scintillation counter. These storage registers permit filtering in addition to stripping the various energy channels of the influence radiation caused by the elements having and energy band centered around a higher energy level.

Abstract: A source of fast neutrons and a detector responsive to the thermal neutron population decay rate are utilized in a well logging instrument. The instrument is placed within a sample retention chamber. The neutron generator is periodically pulsed and the neutron detector is gated on at intervals of 100-150, 150-200, and 800-850 microseconds, respectively, following the termination of each burst of fast neutrons. The detected radiations within these intervals are used to indicate the apparent absorption cross section of the small fluid sample within the chamber. The absorption cross section is measured for a number of small samples of known salinity and calculatable true absorption cross section. A relationship is constructed of the true absorption cross section of the samples versus the measured absorption cross sections of the samples.

Abstract: A method is disclosed for the in situ examination of each subsurface formation penetrated by a borehole to ascertain the cation exchange capacity of such formations within a geological region. Natural gamma ray logging is used to develop signals functionally related to the total gamma radiation and to the potassium -40, uranium and thorium energy-band radiations. A first borehole is traversed by a potential gamma ray spectrometer to provide selected measurements of natural gamma radiation. Core samples are taken from the logged formation and laboratory tests performed to determine the cation exchange capacity thereof. The cation exchange capacities thus are developed then correlated with selected parameters provided by the gamma ray spectrometer to establish functional relationships. Cation exchange capacities of formations in subsequent boreholes within the region are then determined in situ by use of the natural gamma ray spectrometer and these established relationships.

Abstract: An elongated body member, a portion of which forms a chamber for retaining samples of the liquid and steam contents of a geothermal well. A fluid tight seal is formed between an O-ring and a parallel sealing face of a slidable shaft member. The pressure sealing force is adjustably controlled by a spring assembly. The spring assembly is adjusted so that the sealing force must be overcome before a sample is taken. When the sealing force exerted upon the seal is overcome, the sample chamber is placed in fluid communication with the geothermal borehole by a series of passages which include grooves or slots contained in the slidable shaft member. After sampling is complete the seal is reformed allowing the sampler to be retrieved to a surface location.

Abstract: In a neutron induced gamma ray well logging instrument, a neutron generator is pulsed at a clock frequency of 20 KHz. Each neutron burst produces inelastic scattering gamma rays which are detected during a first time interval coinciding with the neutron source being on. Capture gamma rays are detected during a second interval subsequent to the end of each neutron burst. Upon detection of the scattered gamma rays, a detection pulse is transmitted during each of the two detection intervals. Sync pulses are generated at a scaled down frequency rate of 200 Hz within the well logging instrument for transmission to the earth's surface. The scaled-down sync pulses are applied to a phase-locked loop system for regenerating the sync pulses to the same frequency as that of the clock frequency used to pulse the neutron source and to open the detection gates in the borehole instrument.

Abstract: An adapter pad centering device for the side frame of a radially steerable railway car truck with pedestal jaws on opposed end portions thereof for mounting railway car wheel assemblies equipped with a resilient bearing adapter pad mounted between the bearing adapter and the pedestal jaw roof. The adapter pad centering device includes a pair of rigid adapter pad stops on the side frame at opposed sides of the pedestal jaw opening at the roof thereof. Each of the stops has an abutment extending transverse to the side frame. These abutments are spaced so that when the adapter pad is positioned between them, an upper portion of the pad is restrained from significant movement in the longitudinal direction of the side frame. The lower portion of the adapter pad is attached to the bearing adapter and temporarily displaced during steering motions of the truck.

Abstract: A seal assembly for a bypass valve in a well tool such as a packer has a tubular seal carrier with a pair of annular seal elements mounted in a longitudinally spaced relation about the outer periphery thereof. The annular seal elements are anchored in separate grooves around the exterior of the seal carrier such that they are prevented from being dislodged by fluid pressure. Another seal can be provided around the interior of the seal carrier to seal between this seal carrier and a well tool or packer mandrel.

Abstract: A unitary tubular cylindrical gripping member for well tools has variable angled gripping surfaces formed thereon by a plurality of insert teeth elements arranged to provide constant positive gripability of the gripping member in well casings.

Abstract: An electromagnetic sensing system is disclosed for sensing the linear distance between two elements and generating a signal related to the distance. The sensing system utilizes a magnetized initiator as one element, and a magnetic fluxgate as the second element. The magnetic fluxgate creates a flux "window" by locating a biased toroidal saturating coil inside a sensing coil, both of which are located inside a non-magnetic sleeve having an opening or "window" to magnetic flux, with the window being focused on the initiator magnet.

Abstract: A box-like platform having a mast leveling hinge support anchored thereto and a mast structure pivotally attached to the upper end of the hinge support is pivotally attached at one of its ends to an elongated skid unit. The opposite end of the platform is arranged to be raised or lowered by a pair of jacking assemblies connected to the skid unit to effect leveling of the platform. A hydraulic ram having one end connected to the mast and the other end connected to a ram beam supported by a lower extension of the platform enables the mast to be raised to its upright position. By utilizing the ram in conjunction with the leveling characteristic of the platform, the mast assembly can thus be raised to a level and stable condition without the skid unit being perfectly level with respect to the earth's surface. The apparatus permits proper alignment of the mast to the center line of the well to compensate for settlement of the skid unit on an unlevel foundation.

Abstract: A mechanical tubing anchor has a plurality of slip elements mounted in an elongated casing and movable between an extended position and a retracted position. A plurality of friction springs are rigidly secured around an upper end portion of the tubing anchor casing and extend downwardly with the lower end portion of each friction spring resting on an associated slip element. The friction springs extend outward from the casing along their mid-portion to rub against the interior of a well bore and to be compressed in order to bias the slip elements toward their retracted position.