Abstract: A seismic receiver is provided for measuring seismic signals transmitted through the earth and received in a well borehole. A reversible electrical motor drives a harmonic drive reducer which amplifies the torque provided to drive a ball screw. The ball screw moves linearly along the axis of the well borehole to control the extension of a clamp arm into and out of an extended position in contact with subsurface earth adjacent the well borehole. A releasable electric clutch is provided so the receiver is retrievable in the event of a power failure while the clamp arm is extended.

Abstract: Mass, or changes in mass, of a rock specimen are measured to determine the changes in saturation of a rock specimen. Measurements can be obtained in test environments of high temperature or high pressure or both. The mass is rigidly attached beneath a stiff spring and made to vibrate or oscillate at a characteristic frequency. The frequency of oscillation is detected and the data then used to determine mass of the specimen.

Abstract: A method and apparatus for generating a seismic wave in a borehole in the earth is disclosed. A portion of the borehole, which may be the bottom of the hole or any other point along its length, is selected as the site for seismic wave generation. A device is provided to oscillate the borehole fluid in a selected portion of the borehole to establish a resonant standing pressure wave of desired frequency within the fluid. The wave is maintained by continuing to supply energy to the fluid to replace losses due to fluid friction, structural losses and radiated acoustic energy. The standing wave thus created is radiated through the borehole wall into the earth and is eventually received by seismic detectors located on the surface.

Abstract: A high precision, high pressure, volumetric metering pump in which the driving motor is reciprocated by rotation of a ball screw, the drive motor assembly being integral with the driving and pumping shaft, is disclosed.