Hydroacoustics, Inc.

Hydroacustics, Inc.

Roger L Selsam

John V Bouyoucos

Dennis R Courtright

Marvin J Behnfeldt

Robert O Wilson

A water gun seismic source for use in underwater environments has a sleeve valve (100) for opening a jet aperture (37, 101) to enable jets of pressurized water to be emitted for the generation of a seismic signal. The water is pressurized by a drive piston (3) which is reciprocated to a cocked position for pressurizing the water for the jets. A compressed air operated cocking mechanism (4, 7, 8, 76 or 110-199 or 200-260) is coupled to the piston for cocking it. The cocking mechanism may utilize cocking piston (7) slideable on a shaft (4) connected to the drive piston (3) which cocking piston is returned to a position where any load due to such cocking piston is decoupled from the shaft. The sleeve valve (100) may be biased to close the jet aperture ports (101) by compressed air and opened with high timing resolution when the pressurized water held back by the sleeve valve is applied to actuate it (via 40, 41, 50 & 43). Compressed air may be released in the vicinity of the jet aperture ports to be entrained with the jets and assist in forming the vapor cavities which collapse to produce the seismic signal. When compressed air is used to help nucleate the vapor cavities it may also be applied, instead of the pressurized water, to the seat of the sleeve valve to actuate the sleeve valve and open the jet aperture ports.

Seismic source

A method and apparatus for downhole source generation of seismic waves of adjustable frequency by isolating a volume of liquid in a bore hole and cyclically varying the volume by a hydraulically operated transforming piston which varies the pressure of the volume thereby displacing the surrounding strata to generate waves.

Seismic wave generation by a downhole source

A seismic source operable in deep bore holes, and especially suitable for acoustic well logging and geophysical exploration, produces a controlled-spectrum seismic impulse. The source has a hammer which is hydraulically cocked through a hydraulic transformer into a hydraulic spring. Upon command, the hammer can be released, converting stored energy in the spring to kinetic energy of hammer motion. The hammer impacts on a liquid impulse shaping spring which couples impulse energy of controlled spectral width to the formation surrounding the hole by means of a balanced piston assembly which can be prebiased against the side walls of the hole.

Hydraulic actuation of a device for delivering impact energy to a load, such as a pile driver, is provided by a hydraulically operated oscillator having a piston which is reciprocal in a cylinder under hydraulic forces developed by pressurized hydraulic fluid in the cylinder which is switched from supply to return pressure by a valve. The valve is actuated between switching positions by means of trip ports opened and closed by spaced flats on a rod which connect the piston to an impact delivering member, such as the ram of the pile driver. The trip ports are connected to the valve for applying pressurized hydraulic fluid either at supply or return pressure thereto so as to shift the valve between the switching positions. The valve is bi-stable in either of its switching positions through the use of latching ports and restricted passageways through which hydraulic fluid flows in amounts sufficient to make up for leakage through the valve which would otherwise allow the valve to drift.

Hydraulically operated impact devices

An impact tool is described which is capable of developing percussive forces for rock drilling, pile driving, seismic exploration and other repetitive high force applications. The tool contains a hammer and a valve which may be hydraulically actuated so as to oscillate; repetitively executing forward and return strokes during each cycle of oscillation. The valve is actuated in the forward stroke direction by being engaged by the hammer, and in the return stroke direction by fluid pressure means so as to switch the pressure in a cavity in which both the valve and the hammer are disposed for developing forces on the hammer so as to sustain its oscillation. A fluid filled pocket is provided into which the valve enters as it moves in the forward stroke direction, after having switched the pressure in the cavity. A passage is provided on the hammer which is dimensioned so that fluid in the cavity is either connected to a channel, the cavity, or entrapped in the pocket, depending on the position of the hammer. A control valve in the channel determines the flow through the channel, and thus the displacement of the valve into the pocket. The displacement is maintained until communication between the pocket and the cavity is provided via the passage. Control is thereby provided over the stroke of the valve and the period between switching of the pressure in the cavity. The hammer stroke length and the frequency and energy of the impacts delivered by the hammer are dependent upon the switching period, and may be varied by the use of the control valve.

Impact tool

Apparatus is described for welding of thermoplastic parts and the like where the heat to melt the surface or surfaces to be joined is produced by friction during high frequency rubbing. The parts are adapted to be placed on a platen which enables the mating surfaces of the parts to be brought into clamping engagement in a welding head. The welding head includes a seismic mass. Stiff flexural members support a plate, against which the parts are clamped with respect to the seismic mass, and which provides for relative vibratory motion of the mating surfaces to be joined. A hydroacoustic driver is coupled to the plate and causes the plate to execute linear vibratory motion at a high frequency, where the stiffness of the flexural members is resonant with the mass of the vibrated portions of the head. Due to the stiffness of the flexural member and the high frequency of vibration, the relative displacement of the mating surfaces to be joined during vibration can be extremely minute. When vibration stops, the restoring force due to the high stiffness of the flexural members brings the parts into alignment without an auxiliary means. The parts fuse together during cooling at the end of the welding cycle. Then the platen is released and the welded parts may be removed from the apparatus.

Hydroacoustic welder

Impact tools are described which are capable of developing percussive forces for rock drilling and other repetitive high force applications. A hydroacoustic oscillator contained in such tools includes a hammer and a valve mechanism which is actuated by the hammer for controlling the flow of pressurized fluid so as to establish pressure variations which sustain the oscillation of the hammer. A number of alternative valve mechanisms are disclosed, each including a valve element, the motion of which is controlled by controlling the flow of fluid with respect to the valve element as the hammer and valve element move relative to each other. Such flow control is afforded by chambers defined by the valve element; hydraulic fluid flow with respect to which is controlled so as to determine the deceleration of the valve element and the motion of the element in its actuation by the hammer.

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Fairport, NY, United States of America

Roger L Selsam