Marine acoustic source

An acoustical source for generating within a body of water an acoustic signal where said signal is created by the explosive release of a pressurized gas, said source comprising:

• a housing defining two chambers separated by a partition, said chamber communicating with said water through ports situated immediately adjacent said partition;
• a central guide shaft extending through both chambers, said shaft provided with apertures longitudinally disposed through the length of said shaft so as to enable gas flow therethrough;
• each chamber provided with a shuttle slidably and sealingly disposed along said shaft such that each shuttle are capable of simultaneous relative movement and also capable of independent, nonsimultaneous relative movement therealong;
• and
• actuation means operatively coupled to said shuttles so as to enable said shuttles to confine charges of pressurized gas within said chambers and quickly release said charges into said water through said ports.

An acoustical source for generating within a body of water an acoustic signal, said source comprising:

• a housing defining two chambers, each said chamber provided with a port through which said chamber is capable of direct communication with said water;
• a hollow guide shaft extending through said housing about the main axis of said housing so as to establish fluid communication between said chambers;
• a shuttle slidably and partially disposed in each chamber of said housing along said shaft, each said shuttle adapted to move independently between a first position and a second position;
• and
• force producing means operatively coupled to said shuttle so as to cause said shuttle to undergo movement between first and second positions.

A gas gun for offshore seismic surveying which comprises:

• a housing comprising two chambers arranged end-to-end along a common axis, a partition separating the two chambers, and a separate port in the wall of the housing proximate each side of the partition;
• a shaft extending axially in the housing on each side of the partition;
• a separate shuttle valve within the housing on each side of the partition for each chamber, each shuttle valve movably mounted on the shaft to be independently moveable along the shaft between a seated position in the housing closing each respective chamber from each respective port, and an unseated position opening each respective chamber to each respective port;
• a first passageway in the shaft arranged to transmit high pressure gas into said chamber;
• and
• a trigger for each chamber operable to cause movement of each respective shuttle valve from a seated to an unseated position.

A gas gun for offshore seismic prospecting which explosively releases bubbles of gas into water surrounding the gun, which comprises:

• a housing having a longitudinal axis and closed at each end;
• a partition dividing the housing into two end-to-end chambers;
• at least one set of vents in each chamber adjacent the partition;
• a shaft extending axially within the housing from one end of the housing to the other end and passing through the partition, the portion of the shaft spanning the sets of vents being enlarged in diameter relative to the remaining two end portions of the shaft;
• a separate shuttle valve in each chamber mounted on the shaft in axially slidable relation to slide along the shaft between a closed position closing off each respective chamber from the set of vents in the chamber and an open position opening each respective chamber to the set of vents in the chamber;
• each shuttle valve comprising a hollow cylindrical member having an outside diameter smaller than the inside diameter of each respective chamber to define a reservoir chamber and an inside diameter greater than the shaft diameter to define a return chamber.
• a separate valve member attached to the end of each cylindrical member facing toward the set of vents, said valve member having an axial passageway adapted to receive the enlarged portion of the shaft spanning the set of vents in a slidable, fluid-tight relation to slide along the enlarged portion of the shaft;
• a separate piston member attached to the other end of each cylindrical member, said piston member having an outer surface adapted to slide within each respective chamber in a fluid-tight relation, and an axial passageway adapted to receive an end portion of said shaft in a sliding fluid-tight relation;
• each said valve member having a seating surface on the surface of the valve member facing toward each respective piston member;
• a valve seat mounted within each chamber in a position to receive the seating surface of each respective valve member when each respective shuttle valve is in a closed position;
• a first passageway in said shaft adapted to convey gas from outside the housing to each return chamber;
• a separate passageway adapted to convey gas from outside the housing to each chamber between the end of the housing and the piston member in the chamber;
• and
• a separate third passageway adapted to convey gas from outside the housing to each reservoir chamber.

A marine acoustic generator for generating within a liquid an acoustic signal where said signal is created by the explosive release in said liquid of a pressurized gas, said source comprising:

• a housing defining a larger and smaller diameter bore, said smaller diameter bore defining a chamber which is provided with a sealable port at one end through which said chamber communicates with said liquid;
• a guide shaft extending through said bores along an axis;
• a shuttle slidably and partially disposed in said chamber along said guide shaft;
• a first means for locking and maintaining said shuttle in a first position to thereby confine a pressurized gas charge within said chamber;
• and
• a second means to abruptly release said shuttle to a second position thereby directly releasing said pressurized charge through said port into the medium wherein said guide shaft has a larger diameter portion and a smaller diameter portion, said larger diameter situated at the port end of said housing and operatively communicating with said first and second means, and wherein said shuttle comprises a first piston and a second piston, the first and second piston situated and interconnected in spaced relation such that the first piston is slidably and sealingly disposed on said larger diameter portion of said shaft, and the second piston is slidably and sealingly mounted within said smaller diameter bore and slidably and sealingly mounted on said smaller diameter portion of said shaft.

A repetitive acoustic source for generating within a liquid an acoustic signal where said signal is created by the explosive release of a pressurized gas within said liquid, said source comprising:

• a housing comprising a reservoir chamber for confining therein a charge of pressurized gas and provided with a main port through which said reservoir chamber communicates with said liquid;
• a shuttle having a larger-diameter piston sealingly engaged to the exterior of said reservoir chamber and a smaller-diameter piston slidably and sealing mounted inside said reservoir chamber;
• and
• force-producing means operatively coupled with said shuttle so as to cause said shuttle to move between a first and second position thereby directly releasing said charge through said main port into said liquid wherein said force-producing means comprises;
• first means for locking and maintaining said shuttle in said first position to thereby confine said charge of pressurized gas within said reservoir chamber, for abruptly releasing said shuttle from said first position and for propelling said shuttle toward said second position, thereby causing said direct release of said charge;
• and second means for returning said shuttle to said first position, wherein said first means comprise a pressurized gas filling said reservoir chamber, and wherein reservoir chamber for a bottom wall opposed to said main port;
• and said housing has a stop wall outside of said reservoir chamber;
• and a shaft extending from said bottom wall and through said main port to said stop wall;
• and said shaft having a largerdiameter portion outside said reservoir chamber and a smaller diameter portion inside said reservoir chamber;
• and said larger diameter piston of said shuttle is slidably and sealingly mounted on said smaller-diameter portion of said shaft;
• and said pistons of said shuttle are interconnected in spaced relation by a hollow sleeve slidably mounted around said shaft.

An acoustic source for generating within a liquid an acoustic signal where said signal is created by the explosive release of a pressurized gas, said source comprising:

• a housing comprising two chambers longitudinally opposed along a common axis and separated by a partition, each said chamber provided with a port proximate the partition through which said chamber communicates with said liquid;
• a guide shaft extending through said chambers along said axis;
• a pair of shuttles slidably disposed in said housing along said shaft;
• force producing means operatively coupled with said shuttles so as to cause said shuttles to independently move between a first and second position.