Boring or penetrating the earth – With seismic shock generating
Reexamination Certificate
1999-10-01
2001-09-11
Schoeppel, Roger (Department: 3672)
Boring or penetrating the earth
With seismic shock generating
C181S115000, C181S111000, C181S120000, C367S144000, C367S146000
Reexamination Certificate
active
06286612
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to marine acoustic generators and methods for their operation and use. More specifically, the present invention relates to a method and apparatus to selectively cut off fluid flow to any one of an array of marine acoustic generators.
2. Description of the Prior Art
Seismic exploration of subsea formations has involved the use of a variety of differing tools and techniques. One of the most successful tools for a marine seismic exploration is the marine acoustic generator which are commonly referred to as “airguns.”
In a general embodiment, the airgun comprises a body in which a shuttle reciprocates between an open and a closed position so as to define an internal cavity. Air is supplied to and pressurized within the cavity until a selected pressure is achieved. The shuttle is then released to exhaust this pressurized air into the surrounding water to create a primary pressure pulse and a series of secondary pulses. It is these pulses which are useful in seismic evaluation.
Disadvantages associated with contemporary marine acoustic generators arise when one in an array of such generators demonstrates a leakage of fluid. Such leakage distorts the signal produced by the operation of the leaking generator and other generators in the array. Accordingly, prior procedure has required that the entire array be shut down and then retrieved on the streaming vessel. It is then necessary to locate the malfunctioning device, replace or repair the generator, restream the array and then repeat the prior seismic track. For obvious reasons, such retrieval of efforts are very costly terms of lost hours and equipment charges.
Disadvantages associated with prior marine acoustic generators also included the danger associated with their disassembly and repair. In this connection, it is not always obvious that a given device still contains a quantity of pressurized fluid (water or air). As a result, attempts to disassemble the device has often resulted in injury and death as a result of accidental explosions of these devices.
SUMMARY OF THE INVENTION
The present invention addresses the above and other disadvantages of prior marine acoustic systems by providing a method and apparatus to selectively shut off pressurized fluid flow to one or more generators.
In a general embodiment, the present invention comprises a valving system which is adapted to be used with existing marine acoustic generators to provide a mechanism to selectively disable one or more generators comprising an array of such generators. The instant system also enables visual detection of the disabled generators and further provides means to vent such generators to prevent accidental explosion during inspection and/or disassembly.
In a preferred embodiment, the present invention comprises a housing defining an inlet, an outlet and an internal cavity where a shuttle is reciprocally disposed in said cavity between a first and a second position. The housing further defines a series of fluid flow portals disposed about the shuttle in said housing where some of said portals may be closed, and thus air redirected, upon the actuation of a second piston which is also reciprocally disposed in said housing. In one preferred embodiment, the second piston defines a solenoid.
The inlet is coupled via a pressurized fluid line to a supply of pressurized air. The outlet is coupled via a second pressurized line to the marine acoustic generator.
During operation of the marine acoustic generator, air passes unobstructed through the subject valve to be released by the acoustic generator in the generation of acoustic pulses. Upon receipt of a discrete electrical signal, however, the solenoid in the valve moves to a “closed” orientation, thereby selectively disabling the generator by preventing the continuing flow of air to said generator.
The present invention presents a number of advantages over the prior art. One such advantage is the ability to selectively disable a malfunctioning acoustic generator without the need for the wholesale shutdown and retrieval of the seismic array. In such a fashion, significant savings in terms of cost and time may be observed.
Another advantage of the invention is the ability to safely vent a pressurized generator prior to inspection and disassembling. In such a fashion, serious injuries may be avoided.
REFERENCES:
patent: 3612210 (1971-10-01), Loper
patent: 3679021 (1972-07-01), Goldberg
patent: 4210222 (1980-07-01), Chelminski et al.
patent: 4240518 (1980-12-01), Chelminski
patent: 4286687 (1981-09-01), Fiske
patent: 4798261 (1989-01-01), Chelminski
patent: 5018115 (1991-05-01), Pascouet
patent: 5128907 (1992-07-01), Pascouet
patent: 5144596 (1992-09-01), Pascouet
Sankey & Luck L.L.P.
Schoeppel Roger
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