Abstract: A multi-mode receiver sonde having individual receiver stations within a semi-rigid receiver array. The semi-rigid receiver array is adapted to decouple noise (tool-mode noise and/or road-noise) at one location within the receiver array from other locations within the receiver array by using compliant spacers between the receiver stations to absorb and scatter the noise.In preferred embodiments, multi-mode receiver stations are presented which provide a common ground for output signals detected by the receiver stations. Additional embodiments provide for combining the output signals into composite signals which represent a selected borehole propagation mode.In one highly preferred embodiment, the use of transducer detectors which have a flat frequency response over a selected bandwidth allows for accurate comparisons between composite signals so that changes in phase and amplitude over distance and time can be determined.

Abstract: A multi-mode receiver sonde having individual receiver stations. The receiver stations have transducers which have a flat frequency response over a selected bandwidth so that there is an approximately constant ratio in amplitude and substantially little phase difference between the response signal and an input acoustic signal from a liquid containing borehole.The wide-band output response signals are combined to form composite signals which represent selected borehole propagation modes. Accurate comparisons can then be made between the composite signals obtained by separate receiver stations so that changes in phase and amplitude over distance and time can be determined.In one highly preferred embodiment, the receiver sonde has a semi-rigid receiver array. The semi-rigid receiver array is adapted to decouple noise (tool-mode noise and/or road-noise) in one location within the array from other locations within the array by using compliant spacers between the receiver stations to absorb and scatter the noise.

Abstract: A rotational geophone is provided. This rotational geophone employs a coil mounted on a torsional wire in a static magnetic field to detect movement of the frame relative to the coil. This rotational geophone may also be combined with a velocity geophone to obtain seismic data representing shear waves traveling in a particular direction.

Abstract: A method and apparatus for obtaining seismic records representing shear waves detected preferentially in a given direction of propagation. The apparatus comprises a velocity transducer deployed to measure the instantaneous particle velocity perpendicular to the direction of propagation of the wave and a rotational transducer measuring the instantaneous rate of particle rotation.

Abstract: A method and apparatus for measuring and identifying up- and down-traveling waves wherein both a velocity-sensitive and pressure-sensitive transducer are disposed at a point below the earth's surface, as for example in a borehole that is refilled. The pressure transducer is designed to provide intimate contact with the formation surrounding the borehole, and in addition, is the electrical equivalent of the velocity transducer.

Abstract: A data transmission system for use in transmitting data from a well to a surface location. The well data is converted to a voltage and used to control the frequency of an oscillator whose output frequency is transmitted to the surface. At the surface a second voltage-controlled oscillator is adjusted until its frequency and phase matches the signal transmitted from the well. The voltage required to match the frequency of the second oscillator to the frequency of the transmitted signal is then equal to the value of the well data.

Abstract: A highly directional acoustic source for use in a well logging system wherein a fluid-filled tube is provided with a transducer at one end and an acoustic reflector at the other end to reflect the acoustic beam into the formation. The transducer is excited at two frequencies whose difference is the desired frequency and the tube is made sufficiently long to produce parametric generation of the difference frequency.