Communications – electrical: acoustic wave systems and devices – Seismic prospecting – Offshore prospecting
Reexamination Certificate
1999-03-16
2001-10-09
Williams, Hezron (Department: 2862)
Communications, electrical: acoustic wave systems and devices
Seismic prospecting
Offshore prospecting
C367S020000
Reexamination Certificate
active
06301193
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to marine seismic surveying and more particularly to floatation system for use in marine seismic surveying.
In marine seismic surveying, to obtain geophysical information relating to the substrata located below the sea bottom, seismic sources, generally acoustic transmitters, adapted to produce pressure pulses or shock waves under water, are towed beneath the water surface behind a marine vessel. The shock waves propagate into the substrata beneath the sea where they are refracted and reflected back to the sea. The returning shock waves are detected by sensors (usually hydrophones) and the useful data contained in the signals produced by the sensors is processed to determine the geophysical structure of the substrata.
Air guns or gas guns are frequently used as acoustic transmitters. Usually, several air guns are placed in spaced relation to each other in a subarray. One or more air gun subarrays are towed behind a marine vessel beneath the sea surface. During operation, all air guns in a subarray are activated simultaneously to produce a desired overall pressure pulse from that subarray. The pulse characteristics, such as the frequency, bubble ratio and amplitude, of the overall pressure pulse produced by an air gun subarray is a function of the characteristics of the pressure pulses produced by the individual air guns and the physical arrangement of the air guns in that air gun subarray.
In order to repeatedly produce and transmit pressure pulses having known characteristics under water, it is important that the air gun subarray is maintained at a constant depth below the water surface and in a near straight line horizontal position. Air gun subarrays presently in use are generally more than fifty (50) feet long and weigh several hundred pounds. To tow such an air gun subarray below the water surface, it is a common practice in the art of seismic surveying to pivotly attach a single or multiple floatation devices (buoys) along the length of the air gun subarray by means of a plurality of links. The floatation device maintains the air gun subarray at or near a constant depth below the water surface when the subarray and the floatation device combination (or the seismic source system) are towed behind a vessel.
Conventional floatation systems for use in marine seismic acquisition typically consist of sealed metallic containers, sealed members having solid floatation material in separate compartments, or sealed members that communicate with one another using a series of valves and a regulated air supply. Flotation systems consisting of sealed metal containers frequently suffer from premature failure in operation because of water infiltration of the inflexible metal container. Floatation systems consisting of sealed members having solid floatation materials in separate compartments are complex and difficult to monitor in operation. Floatation systems consisting of sealed members that communicate with one another and include a regulated air supply are complex and require a regulated power supply, valving, and a controller.
The present invention is directed to overcoming one or more of the limitations of the existing floatation systems used for marine seismic energy source.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a floatation device for a marine seismic energy source is provided that includes a head float, n tubular members coupled to the head float, n-1 couplings coupled to the tubular members for sealing an end portion of the tubular members, each coupling including an air valve, and a tail member coupled to an end portion of one of the tubular members for sealing the end portion of the one tubular member.
According to another aspect of the present invention, a marine seismic energy source is provided that includes a floatation device and one or more marine seismic energy sources coupled to the floatation device. The floatation device includes a head float, n tubular members coupled to the head float, n-1 couplings coupled to the tubular members for sealing an end portion of the tubular members, each coupling including an air valve; and a tail member coupled to an end portion of one of the tubular members for sealing the end portion of the one tubular member.
According to another aspect of the present invention, a marine seismic acquisition system is provided that includes a controller for controlling the operation of the marine seismic acquisition system, one or more marine seismic sensors for monitoring seismic energy coupled to the controller, and a marine seismic energy source for generating seismic energy coupled to the controller. The marine seismic energy source includes a floatation device and one or more marine seismic energy sources coupled to the floatation device. The floatation includes a head float, n tubular members coupled to the head float, n-1 couplings coupled to the tubular members for sealing an end portion of the tubular members, each coupling including an air valve; and a tail member coupled to an end portion of one of the tubular members for sealing the end portion of the one tubular member.
In accordance with another aspect of the present invention, a floatation member is provided that includes a tubular member having an interior chamber with first and second ends, a first sealing member for sealing the first end of the interior chamber of the tubular member, and a second sealing member for sealing the second end of the interior chamber of the tubular member. At least one of the sealing members includes a valve for injecting a buoyant fluid into the interior chamber of the tubular member.
In accordance with another aspect of the present invention, a sealing member for sealing a hollow tubular member is provided that includes a hollow tubular housing having a first end and a second end, a partition positioned within the hollow tubular housing for dividing the interior of the hollow tubular housing into a first interior portion and a second interior portion, and a valve coupled to the hollow tubular housing.
In accordance with another aspect of the present invention, a method of operating a marine seismic energy system is provided that includes providing a plurality of separate flexible buoyant members, coupling the flexible buoyant members, injecting a buoyant fluid into the flexible buoyant members; and supporting at least one marine seismic source beneath the surface of a body of water using one or more of the buoyant members.
In accordance with another aspect of the present invention, a method of floating one or more elements below the surface of a body of water is provided that includes providing a tubular floatation member, sealing the end of the tubular floatation member, injecting a buoyant fluid into the tubular floatation member adjacent to one of the ends of the tubular floatation member, and supporting one or more elements below the surface of a body of water using the tubular floatation member.
In accordance with another aspect of the present invention, a method of joining floatation devices is provided that includes providing a flexible hollow coupling including a valve for injecting a buoyant fluid into the floatation devices.
REFERENCES:
patent: 4038630 (1977-07-01), Chelminski
patent: 4552086 (1985-11-01), Böe et al.
patent: 4686660 (1987-08-01), Gjestrum et al.
patent: 4716553 (1987-12-01), Dragsund et al.
patent: 4831599 (1989-05-01), Dragsund et al.
patent: 5144588 (1992-09-01), Johnston et al.
patent: 5319609 (1994-06-01), Regnault
patent: 5943293 (1999-08-01), Luscombe et al.
patent: 6011753 (2000-01-01), Chien
patent: 6026056 (2000-02-01), Lunde et al.
Charvoz David C.
Martin Dallas
Input / Output Inc.
Madan Mossman & Sriram PC
Taylor Victor J.
Williams Hezron
LandOfFree
Floatation device for marine seismic energy sources does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Floatation device for marine seismic energy sources, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Floatation device for marine seismic energy sources will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2605660