US3840845A
Expired / Lapsed
US
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Method of initiating and collecting seismic data related to strata underlying bodies of water using a continuously moving seismic exploration system located on a single boat using separate streamers
Assignee: Chevron USA Inc
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Filing: 1973-06-29
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Granted: 1974-10-08
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Expires: 1993-06-29
Abstract
Abstract Description is hereinafter had to a method for collecting seismic data related to two-dimensional subsurface coverage of strata underlying a body of water. In accordance with the present invention, a continuously moving marine seismic exploration system includes a repetitive seismic source and two separate streamers of hydrophones trailing behind a single seismic boat traversing the body of water along a straight base course line. The seismic source is fired at a selected repetition rate to generate a series of firing stations coincident with the base course line. The streamers include pluralities of hydrophones connected to the seismic boat by means of a bridle assembly extending from the rear of the boat; the bridle locates each streamer at different depths; each streamer terminates in a paravane assembly connected to its trailing end. In operation, the paravane of a first streamer has a rudder assembly whose position is arranged, as by radio commands from the seismic boat or under mechanically induced programmed commands, to maintain the trailing end of the first streamer along a straight line parallel to the base line and offset from it by a selected but substantially constant distance much greater than that for the leading end of the streamer. Thus, because of forces acting thereon, the first streamer assumes the shape of a modified catenary. On the other hand, the second streamer is arranged to trail behind the boat along a vertical plane substantially coincident with the base course line. The outer boundary of points is equal to one-half the offset distance of the trailing end of the first streamer from the base course line. Since the seismic boat proceeds along the base course line at a constant speed, a grid of depth points including a series of in-line seismic points are obtained. When sets of traces associated with the offset and in-line seismic depth points are processed, the contribution of the normal and cross movement of each trace can be easily determined since the in-line traces are devoid of cross dip movement contributions. In order for the swathe of sourcereceiver positions at the surface to be clearly identified with the series of center point arrays, the streamers can also be provided with a series of sonic transducers along this length. Sonic pulses are emitted from a transmitter aboard the boat (preferably after seismic source is activated, but before the reflections are received at the hydrophones) and are subsequently detected by the streamer transducers and retransferred back to the boat. In that way, identifying the instantaneous locations of the transducers by means of digital ranging techniques can be achieved. In one form of the invention, the binary indications of the travel time of the sonic wave, and hence the instantaneous positions of the transducers per each shot, are directly encoded onto the field magnetic tape for later use in mapping of the subsurface under survey.
Inventors
- 👤 R Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 14:49
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/24; G01V1/38; G01V1/3808
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
476 words
A seismic data collecting method for determining the threedimensional configuration of an earth formation underlying a body of water by means of a continuously moving marine seismic exploration system including a repetitive seismic source means and pluralities of hydrophones arranged in a first and second separate marine streamers, comprising the steps of: a. moving, by single seismic boat means traversing a substantially straight base course line, said repetitive seismic source means and said first and second streamers, b. said first streamer being moved so that center points between all possible source point-hydrophone station pairs during movement of said seismic boat along said base course line form a two-dimensional grid of center points laterally off-set to one side of said base course line including cross sets of center points aligned substantially perpendicular to said base course line, the total offset length of said two-dimensional grid of center points in said cross direction remaining substantially constant during the surveying operation, said movement of said first streamer being further characterized by allowing the trailing end of said streamer to trail behind said seismic boat offset relative to said base line and the leading end of the first streamer to lead from a series of locations closer to said base line than said trailing end; c. said second streamer being simultaneously moved so that center points between all possible source point-hydrophone stations pairs form an in-line, one-dimensional line of center points lying substantially in a vertical plane intersecting said base course line, said movement of said Second streamer being further characterized by said streamer being positioned in a vertical plane coincident with said base course line, each of said in-line center points being aligned in the cross direction with said grid of center points generated in association with said first marine streamer; d. firing said seismic source means in sequence at known times to initiate travel of said seismic energy downward toward seismic discontinuities within said earth formation; e. providing a multibit digital positional data indication of the position of at least one target aboard at least one of said streamer relative to said seismic boat means; and f. receiving at said pluralities of hydrophones after firing of said seismic source means, separate reflection signals representative of the energy received as the hydrophones are positioned at a plurality of known hydrophone stations so as to provide first and second sets of multibit seismic data indications, said first set of indications being associated with cross sets of information associated with cross sets of center points generated by source point-hydrophone pairs associated with said first marine streamer, said second set of indications being associated with said one-dimensional line of center points; g. cooperatively processing said first and second sets of indications so as to provide identification of normal moveout as well as in-line and cross components of dip moveout within said data.
Claim 2
Dependent Claim
476 words
A seismic data collecting method for determining the threedimensional configuration of an earth formation underlying a body of water by means of a continuously moving marine seismic exploration system including a repetitive seismic source means and pluralities of hydrophones arranged in a first and second separate marine streamers, comprising the steps of: a. moving, by single seismic boat means traversing a substantially straight base course line, said repetitive seismic source means and said first and second streamers, b. said first streamer being moved so that center points between all possible source point-hydrophone station pairs during movement of said seismic boat along said base course line form a two-dimensional grid of center points laterally off-set to one side of said base course line including cross sets of center points aligned substantially perpendicular to said base course line, the total offset length of said two-dimensional grid of center points in said cross direction remaining substantially constant during the surveying operation, said movement of said first streamer being further characterized by allowing the trailing end of said streamer to trail behind said seismic boat offset relative to said base line and the leading end of the first streamer to lead from a series of locations closer to said base line than said trailing end; c. said second streamer being simultaneously moved so that center points between all possible source point-hydrophone stations pairs form an in-line, one-dimensional line of center points lying substantially in a vertical plane intersecting said base course line, said movement of said Second streamer being further characterized by said streamer being positioned in a vertical plane coincident with said base course line, each of said in-line center points being aligned in the cross direction with said grid of center points generated in association with said first marine streamer; d. firing said seismic source means in sequence at known times to initiate travel of said seismic energy downward toward seismic discontinuities within said earth formation; e. providing a multibit digital positional data indication of the position of at least one target aboard at least one of said streamer relative to said seismic boat means; and f. receiving at said pluralities of hydrophones after firing of said seismic source means, separate reflection signals representative of the energy received as the hydrophones are positioned at a plurality of known hydrophone stations so as to provide first and second sets of multibit seismic data indications, said first set of indications being associated with cross sets of information associated with cross sets of center points generated by source point-hydrophone pairs associated with said first marine streamer, said second set of indications being associated with said one-dimensional line of center points; g. cooperatively processing said first and second sets of indications so as to provide identification of normal moveout as well as in-line and cross components of dip moveout within said data.
Claim 3
Dependent Claim
81 words
The method of claim 1 in which step (e) is further characterized by the substeps of: i. generating a sonic wave for travel from a known geodetic position relative to said boat means; ii. detecting said wave at targets aboard both said first and second streamers; iii. digitally determining the travel time of said wave between targets aboard said first and second streamers so that accurate annotation of position and data associated with said first and second streamers can be achieved;
Claim 4
Dependent Claim
102 words
The method of claim 2 in which substep (iii) includes: i. initiating counting by counting means as said sonic wave is generated; ii. terminating counting when said wave is detected at said streamer targets; iii. storing said counts in a register; iv. generating a time-dependent enabling signal by means of word and block counters connected to said register so as to cause gating of said counts from said register; v. recording said counts as multibit positional digital data indications on a header section of said magnetic tape so as to identify the target positions aboard each streamer as seismic data is received.
Claim 5
Dependent Claim
77 words
The method of claim 3 with the additional steps of: i. processing said multibit positional digital indications to determine the range from said known geodetic position to said streamer targets of each streamer, and ii. transforming the three-dimensional coordinates of said known geodetic positions to establish three-dimensional coordinates of said targets for each first and second streamers so as to enable accurate annotations of data associated with respective source point-hydrophone pairs of each first and second streamers.
Claim 6
Dependent Claim
372 words
A seismic data collecting method for determining the three-dimensional configuration of an earth formation underlying a body of water by means of a continuously moving marine seismic exploration system including a repetitive seismic source means and pluralities of hydrophones arranged in separate first and second streamers, comprising the steps of: a. moving, by single seismic boat means traversing a substantially straight base course line, said repetitive seismic source means and said first and second streamers; b. said first streamer being moved so that center points between all possible source point-hydrophone station pairs during movement of said seismic boat along said base course line form a two-dimensional grid of center points laterally offset to one side of said base course line including cross sets of center points aligned substantIally perpendicular to said base course line; c. said second streamer being simultaneously moved so that center points between all possible source point-hydrophone station pairs form an in-line, 1-dimensional line of center points lying substantially in a vertical plane intersecting said base course line, each of said in-line center points being associated in the cross direction with one of said cross sets of center points generated in association with said first marine streamer; d. firing said seismic source means in sequence at known times to initiate travel of said seismic energy downward toward seismic discontinuities within said earth formation; e. providing a multibit digital positional data indication of the position of at least a target aboard at least one of said streamers relative to said seismic boat means; and f. receiving at said plurality of hydrophones after firing of said seismic source means, separate reflection signals representative of the energy received as the hydrophones are positioned at a plurality of known hydrophone stations so as to provide first and second sets of multibit seismic data indications, said first set being associated with said cross sets of center points generated in association with said first marine streamer, said second set being associated with said one-dimensional in-line set of center points generated in association with said first marine streamer; and g. cooperatively processing said first and second sets of indications to distinguish normal moveout as well as in-line and cross components of dip movout within such data.
Claim 7
Dependent Claim
372 words
A seismic data collecting method for determining the three-dimensional configuration of an earth formation underlying a body of water by means of a continuously moving marine seismic exploration system including a repetitive seismic source means and pluralities of hydrophones arranged in separate first and second streamers, comprising the steps of: a. moving, by single seismic boat means traversing a substantially straight base course line, said repetitive seismic source means and said first and second streamers; b. said first streamer being moved so that center points between all possible source point-hydrophone station pairs during movement of said seismic boat along said base course line form a two-dimensional grid of center points laterally offset to one side of said base course line including cross sets of center points aligned substantIally perpendicular to said base course line; c. said second streamer being simultaneously moved so that center points between all possible source point-hydrophone station pairs form an in-line, 1-dimensional line of center points lying substantially in a vertical plane intersecting said base course line, each of said in-line center points being associated in the cross direction with one of said cross sets of center points generated in association with said first marine streamer; d. firing said seismic source means in sequence at known times to initiate travel of said seismic energy downward toward seismic discontinuities within said earth formation; e. providing a multibit digital positional data indication of the position of at least a target aboard at least one of said streamers relative to said seismic boat means; and f. receiving at said plurality of hydrophones after firing of said seismic source means, separate reflection signals representative of the energy received as the hydrophones are positioned at a plurality of known hydrophone stations so as to provide first and second sets of multibit seismic data indications, said first set being associated with said cross sets of center points generated in association with said first marine streamer, said second set being associated with said one-dimensional in-line set of center points generated in association with said first marine streamer; and g. cooperatively processing said first and second sets of indications to distinguish normal moveout as well as in-line and cross components of dip movout within such data.
Claim 8
Dependent Claim
20 words
The method of claim 5 in which said multibit positional and seismic data indications are recorded onto seismic magnetic tape.
Claim 9
Dependent Claim
65 words
The method of claim 5 in which step (e) is further characterized by the substeps of: i. generating a sonic wave for travel from a known geodetic position relative to said boat means; ii. detecting said wave at targets aboard each first and second marine streamers; and iii. digitally determining the travel time of said wave between said known geodetic position and said boat means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |