Method and apparatus for tuning the rise time of the initial pulse of an air gun
OwnerStephen Chelminskiinventor
Life of this patent
Estimating the term…
Abstract
An air gun intended for use in generating seismic energy impulses, i.e. acoustical waves, in a body of water that provides improved performance by adjusting the length of the firing chamber in order to tune the rise time from zero pressure to peak pressure and to increase or decrease the slope of the initial pulse. By selecting the length of the firing chamber, the rise time of the initial pulse is tuned to increase low frequencies and reduce objectionable high frequencies to help in mitigating damage to marine life and the marine environment and to provide greater penetration of the seismic signal through for example basalt and sub-basalt structures.
Claims46
An air gun, comprising:
- a housing having an operating chamber and discharge ports;
- a firing piston movable within the housing;
- a firing chamber attached to the housing, the firing chamber having a firing chamber seal adjacent an inner edge of the discharge ports providing zero acceleration distance and the firing chamber having a length that is at least two times greater than the diameter of the firing chamber;
- and
- the average rising slope of the primary pressure pulse from firing the air gun is less than 0.4 bar-m/ms.
An air gun for seismic exploration, comprising:
- an air gun having a firing chamber;
- and
- wherein the rise time to peak of the initial pulse is tuned by varying the length of the firing chamber and a specific length of the firing chamber is selected based on a length of approximately 0.343 meters per millisecond (1.126 feet per millisecond) of desired rise time to peak of the initial pulse.
A method of adjusting the rise time and the frequency content of the initial pulse of an air gun comprising:
- tuning the rise time of the initial pulse by selecting a length of the firing chamber to a length approximately 0.343 meters per millisecond (1.126 feet per millisecond) of desired rise time to peak of the initial pulse.
A method of tuning the rise time of the primary pressure pulse of an air gun, comprising:
- selecting a length of a firing chamber that is at least two times greater than the diameter of the firing chamber;
- sealing the firing chamber along an inner edge of the discharge ports providing zero acceleration distance;
- producing an average rising slope of the primary pressure pulse from firing the air gun in a range of 0.05 bar-m/ms to 0.30 bar-m/ms;
- producing a port exit area at a rate greater than or equal to 50 square centimeters per millisecond;
- and
- producing a rise time from zero to peak pressure of the primary pressure pulse that is greater than 1.2 milliseconds.
Dependencies are inferred from the claim text.