Abstract: Methods and apparatus for directly and more accurately assaying radiological characteristics of elements with a subsurface formation surrounding a bore hole. An instrument is provided which comprises a pulsed neutron source, a high resolution gamma ray detector and means for isolating a portion of the instrument in a neutron absorbing envelope comprised of a solution of fresh water and a neutron absorbing substance. This isolation means eliminates deleterious bore hole effects and maximizes the measurement of formation capture gamma rays. The applications of the present invention include measuring the presence of an element and measuring the ratio of two elements within a formation surrounding a bore hole.

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: After drilling an earth borehole, the drill pipe and drill bit are removed from the borehole and the drill pipe is reinserted into the borehole. A flexible hose such as a fire hose, and having a retro-nozzle at its lower end, is then pumped down through the interior of the drill pipe and a portion of the hose is pumped out through the end of the drill pipe for a desired distance. A well logging instrument is pumped through the flexible hose which extends down past the bottom of the drill pipe and well logging operations are performed through the flexible hose. In very hot wells, the drilling mud or other circulating fluid can continue to be pumped through the flexible hose to provide cooling of the well logging instrument.

Abstract: An elongated borehole logging instrument includes a permanent magnet linear reciprocating motor. The motor powers a sliding sleeve which has attached to its outer perimeter a series of reversible vanes. The vanes engage the mud cake or the borehole wall and thus generate a force opposite to the direction of the vane slant. The motor has a stationary electromagnetic field comprised of a plurality of coils connected to the control electronics. The floating outer sleeve has permanent magnets all oriented in the same direction. As the coils are pulsed alternatingly, the magnets are either repulsed or attracted to thus generate a reciprocating motion which transferred to the vanes moves the tool up or down, depending upon the position of the reversing actuator. The control electronics is responsive to the difference between the velocity of the well logging instrument, functionally related to its acceleration, and the velocity of the well logging cable at the earth's surface.

Abstract: A conventional logging instrument is adapted to traverse a slanted or deviated earth borehole on the end of a conventional logging cable. A heavy, streamlined sinker bar is adapted to be fitted over the cable and to slide freely thereon. Upper and lower stop clamps, separated by approximately 100 feet of cable, are provided on the cable with the lower stop clamp being located approximately 200 feet above the logging instrument. The sinker bar is adapted to slide freely between the upper and lower stop clamps. Since it is unlikely that the logging tool and the sinker bar will become stuck at the same time in a highly deviated borehole, one of two things can happen. If the sinker bar becomes stuck, the cable passes freely through the center of the sinker bar without impeding the logging tool until the upper clamp reaches the limit of its travel. If at that point the logging instrument is descending freely, it can dislodge the sinker bar with a gravitational force.

Abstract: An elongated borehole logging instrument includes a permanent magnet linear reciprocating motor. The motor powers a sliding sleeve which has attached to its outer perimeter a series of reversible vanes. The vanes engage the mud cake or the borehole wall and thus generate a force opposite to the direction of the vane slant. The motor has a stationary electromagnetic field comprised of a plurality of coils connected to the control electronics. The floating outer sleeve has permanent magnets all oriented in the same direction. As the coils are pulsed alternatingly, the magnets are either repulsed or attracted to thus generate a reciprocating motion which transferred to the vanes moves the tool up or down, depending upon the position of the reversing actuator.