WO1998007050A1 - Navire pourvu d'un dispositif trainant monte en serie et technique d'exploitation correspondante - Google Patents

Navire pourvu d'un dispositif trainant monte en serie et technique d'exploitation correspondante Download PDF

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Publication number
WO1998007050A1
WO1998007050A1 PCT/US1997/014362 US9714362W WO9807050A1 WO 1998007050 A1 WO1998007050 A1 WO 1998007050A1 US 9714362 W US9714362 W US 9714362W WO 9807050 A1 WO9807050 A1 WO 9807050A1
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WO
WIPO (PCT)
Prior art keywords
cable
buoy
sensor
seismic
section
Prior art date
Application number
PCT/US1997/014362
Other languages
English (en)
Inventor
Karl A Berteussen
Arne Rokkan
Eivind Fromyr
Original Assignee
Petroleum Geo-Services (Us), Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Petroleum Geo-Services (Us), Inc. filed Critical Petroleum Geo-Services (Us), Inc.
Priority to AU40680/97A priority Critical patent/AU4068097A/en
Publication of WO1998007050A1 publication Critical patent/WO1998007050A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/38—Seismology; Seismic or acoustic prospecting or detecting specially adapted for water-covered areas
    • G01V1/3808—Seismic data acquisition, e.g. survey design

Definitions

  • the present invention relates generally to systems and methods for conducting marine seismic surveys, and more particularly, to a system and method for conducting dragged cable array seismic surveys with a single vessel.
  • Ocean bottom dragged cable arrays capable of being dragged from one location to another have been used as part of a known technique for seismic surveying.
  • systems employing this technique have required multiple vessels for operation.
  • a cable handling vessel lays, drags and retrieves the ocean-bottom cable and receives and records seismic signals.
  • a source vessel generates seismic source signals by towing an acoustic air gun array over the survey area.
  • a single vessel is used for the cable handling and recording operations .
  • U.S. Patent No. 4,516,227 issued to ener, et al., incorporated herein by reference, discloses a dragged cable system using three vessels.
  • the first vessel is a crane boat that implants seismic sources on the sea bottom.
  • the second vessel retrieves the buoys and anchors after the seismic sources have been detonated.
  • the third vessel pulls the dragged cable array and selectively causes the detonation of the seismic sources.
  • Multiple vessel systems are relatively expensive because of costs necessary to operate each vessel dispatched to the survey site.
  • An object of the present invention is to reduce the number of vessels required to perform an ocean-bottom seismic survey by realizing an ocean-bottom cable array system in which all necessary functions are performed by one vessel.
  • a process comprising: deploying seismic sensors at a first location on the sea floor with a vessel; generating source seismic signals from the vessel; receiving reflected seismic signals with the sensors; recording the reflected seismic signals; and dragging the cable with the vessel to a second location on the sea floor.
  • a system comprising: a cable comprising sensors of seismic signals, wherein the cable comprises a sensor section which rests upon the sea floor and a lead section which is attached at a first end to the sensor section; a buoy which is attached to a second end of the lead section of the cable, wherein the buoy suspends the lead section from the sea surface; and a vessel that lays the cable on the sea floor and generates seismic source signals.
  • an ocean bottom seismic sensor array comprising: a cable comprising sensors of seismic signals, wherein the cable comprises a sensor section which rests upon the sea floor and a lead section which is attached at a first end to the sensor section; a buoy which is attached to a second end of the lead section of the cable, wherein the buoy suspends the lead section from the sea surface; and a collector of seismic signals received by the sensors of the cable.
  • a system comprising: a cable comprising sensor section which rests upon the sea floor and a lead section which is attached at a first end to the sensor section, wherein each sensor of the sensor section comprises a sensor of seismic signals having three orthogonally oriented gimbaled geophone, a hydrophone, and a weight for embedding the sensor in the soil of the sea floor; a buoy which is attached to a second end of the lead section of the cable, wherein the buoy suspends the lead section from the sea surface; a vessel that lays the cable on the sea floor, detaches from the cable and generates seismic source signals; and a collector of seismic signals received by the sensors of the cable.
  • FIG. 1 is a diagram of one embodiment of the invention in which an array completely deployed from the vessel to the sea floor with one end suspended from the sea surface by a buoy.
  • FIG. 2 is a flow chart of one embodiment of the invention showing a process for operating a single vessel system.
  • FIG. 3a is a diagram of one embodiment of the invention m which a cable is being deployed from the vessel.
  • FIG. 3b is a diagram of one embodiment of the invention wherein the cable is completely deployed from the vessel.
  • FIG. 3c is a diagram of one embodiment of the invention m which the vessel is shown generating source seismic signals in the vicinity of the ocean-bottom cable.
  • FIG. 3d is a diagram of one embodiment of the invention in which the vessel is shown dragging the ocean-bottom cable to a location.
  • FIG. 4 is a diagram of a further embodiment of the invention in which the ocean-bottom cable comprises two lead ends suspended from buoys at the surface of the sea.
  • FIG. 5 is a diagram of another embodiment of the invention wherein two ocean-bottom cable arrays are deployed and handled by a single vessel.
  • FIG. 5A is a diagram of yet another embodiment of the invention.
  • FIG. 6 is a side view diagram of an embodiment of the invention showing a buoy for recording and transmitting signals.
  • FIG. 7a is a diagram of an embodiment of the invention comprising a support buoy and a recording buoy.
  • FIG. 7b is a diagram of an embodiment of the invention wherein the recording buoy is the support buoy. It is to be noted, however, that the appended drawings illustrate only typical embodiments of the invention and are therefore not to be considered a limitation of the scope of the invention which includes other equally effective embodiments.
  • the array 10 comprises a long cable having two sections, a sensor section 11 and a lead section 12.
  • the cable is flexible so that it can be wound on a reel or looped on the deck of a vessel.
  • sensor stations 13 are attached to the cable 17 at specific intervals.
  • the lead section 12 of the cable is an extension of the sensor section 11 except that no sensor stations 13 are attached to the cable.
  • the lead section 12 of the cable is long enough to extend from the surface of the sea 14 to the sea floor 15 so that a significant portion of the lead section 12 rests upon the sea floor 15.
  • the cable 17 is built to withstand the pressures and dragging forces expected to be encountered at, for example, 0.5 km, 1.2 km, and 2 km of depth.
  • the end of the lead section 12 opposite the sensor section 11 is attached to the buoy 16 so that the lead section 12 is suspended from the sea surface 14.
  • a recorder or transmitter of data signals is housed within the buoys 16.
  • the sensor stations 13 include four-component sensors. Three of the components comprise geophones, oriented along X, Y, and Z axes, to detect particle motion in each of these directions.
  • the geophones of each station are gimbaled, and any geophone may be used, such as the SM4 produced by Sensor Netherland.
  • the fourth component comprises a hydrophone which detects fluctuations in pressure. Again, there are various hydrophones available to the industry which are suitable for use.
  • An example is the BM4 produced by Basys Netherland.
  • Each station 13 further comprises a four channel, 24 bit crystal digitizer for converting analog seismic signals to digital signals.
  • the sensor section 11 comprises 8 to 24 sensor stations 13.
  • An armored transmission cable 17 is used, such as a standard 7 conductor wireline logging cable manufactured by Rochester.
  • the cable itself is capable of N x 512 KBPS Transmission through N x 35 channels.
  • the cable has a 24 bit resolution, an IDR of greater than 114 dB and a THD of less than .002%.
  • this configuration allows for a sample rate of 2 milliseconds and allows for gam selection to produce the best results for the particular survey.
  • the system has a length of about 6,500 feet. While as many as 17 receiver stations 13 are used on a 7 conductor transmission cable 17 without the need for repeaters, fiber optic cable 17 is employed in some embodiments to increase the transmission distance and number of receiver stations 13, as is known in the art.
  • a recorder is housed within buoy 16 to record data signals as they are received from the sensor stations 13. As the seismic survey is conducted, signals are transmitted through the cable to the recorder in the buoy 16. The data signals are recorded by the recorder on magnetic tapes, compact discs, etc. as they are received by the recorder. After seismic data has been recorded for a particular section of the survey, tapes or discs are retrieved and replaced with blank tapes or discs m preparation for data collection at a new location. Recorders sucn as the Exabyte 8505, which is a 5 Gbyte recorder, are suitable. Similarly, standard microcontrollers, such as the Motorola 68302 microcontroller, are employed for operation control.
  • a transmitter is housed in the buoy 16 for transmission of data by a transmitting antenna mounted on the buoy 16 to a receiving antenna on the seismic vessel 18.
  • the received seismic data is then recorded to the known manner for processing and analysis.
  • the data is plotted and inspected aboard the vessel 18 as the survey is being performed.
  • Standard UHF radios transmit the data. Some radios such as those manufactured by Motorola, which provide a transmission range up to 12 - 14 km, are particularly suitable.
  • the data signals received from the sensor stations 13 are both recorded and transmitted.
  • part of the data is recorded with a recorder as noted above in the buoy 16.
  • a second part of the data is transmitted to the vessel 18 where it is recorded.
  • a low speed transmission means transmits at least one channel of data back to the vessel 18.
  • the transmitter also steps or switches through each channel of the telemetry system so that operators of the system stationed aboard the vessel 18 can determine if data signals are being properly received over each channel. When the data signals for a given channel are not being transmitted to the vessel, they are automatically recorded m the buoy 16 by the recorder.
  • the transmitter in this embodiment is a half duplex radio that receives command, time break and navigation signals from the vessel 18 and transmits at least one channel of data to the vessel 18.
  • a power pack for the system must also be provided.
  • alkaline and lithium batteries are used.
  • 20 to 30 rechargeable 6-volt lithium batteries are used to provide the various voltages necessary to operate the microcontroller and the recorder.
  • Standard batteries such as 6 volt alkaline batteries having 10X10X10 cm elements produced by Panasonic, are suitable. These batteries are removed from the buoy 16 and replaced with recharged batteries at the same time the recording tapes or discs are exchanged.
  • a power pack recorder, radio transmitter, etc. are all placed in the buoy 16.
  • the buoy 16 comprises a float member 20 which imparts buoyancy, and a housing member 21 which contains all of recording and transmitting components.
  • the battery pack 22 is positioned at the bottom of the housing 21.
  • a power conditioner 23 interfaces the battery pack 22 with the electrical devices of the system.
  • the transmission cable 17 is attached to the buoy 16 and connects to the radio 25 and the recorder 26 through an array interface 24.
  • An antenna 27 is positioned at the top of the buoy 16.
  • alternative embodiments are used to support the weight of the lead-in section 12 of the cable 17.
  • FIG 7a support buoy 30 is shown which suspends the lead-in section of the cable 17 from the sea surface 14.
  • a transmission cable 31 extends from the support buoy 30 to the buoy 16.
  • the lead-in section 12 of the cable 17 is suspended by the buoy 16 from the sea surface 14. Because the electronic equipment contained in the buoy 16 must be insulated from the turbulence of wave action at the sea surface, these configurations offer greater insulation characteristics depending on the design of the entire system.
  • the cable 17 is laid 201 on the sea floor by offloading the cable 17 from a vessel 18 as the vessel maintains its forward motion. In this manner, the cable 17 is placed on the ocean floor 15 m a linear pattern.
  • the cable 17 is then dragged into position. Typically, the survey area is charted, and cable 17 must be precisely positioned. Acoustic transponders, which provide range and bearing information to the vessel 18, are used to monitor the location of the cable 17 on the sea floor 15. As shown in Fig. 3b, once the cable 17 is dragged to the correct position, cable 17 is then released 202 nto the sea so that the lead section 12 of the cable 17 is suspended from the buoy 16.
  • a source array 19 is then deployed from the vessel 18 for the generation of seismic signals.
  • the source array comprises towed air guns, implanted ocean-bottom sources, or any other known acoustic source.
  • Vessel 18 then pulls the source array 19 through the water so that seismic source signals are generated 203 at various locations above the cable 17.
  • the seismic signals then propagate down into the substrata of the sea bed where they are reflected by rock formations.
  • the reflected seismic signals are then received 204 by the sensor stations 13 and translated into the electronic seismic data.
  • This seismic data is then transmitted 205 through the cable 17 to the buoy 16.
  • the data is recorded by a recorder m the buoy 16.
  • the data is transmitted via a radio link to the vessel 18 where it is recorded. Referring to Fig. 3d, after the seismic data has been collected for this particular location of the sea bed, the lead section 12 of the cable 17 is attached 207 to the vessel 18. The vessel then drags 207 to the cable to a new location. The cable is then released 208 into the sea. Seismic source signals are again generated, and reflected signals are received and recorded by the cable. This process is repeated 209 until the entire survey is completed.
  • the cable 17 comprises two lead sections 12, which are attached to opposite ends of sensor section 11. This allows the cable to be dragged from either end to transport the cable array 10 from one location to another.
  • a record is located in one of the buoys 16 for recording the seismic data received from different sensor stations 13.
  • two recorders, one in each buoy are used to receive data from the same sensor stations 13 simultaneously to provide redundancy in the system should one of the recorders fail.
  • a transmitter of the seismic data is placed in each of the buoys 16 to transmit data to the vessel 18 for recording.
  • the two transmitters are set up to transmit only data from different sensor stations 13, or in a further embodiment, they send duplicate transmissions of the data from the same sensor stations 13. This again provides redundancy to the system should one of the transmitters fail.
  • the system comprises multiple arrays which are placed on the sea floor m a particular configuration. As shown in Figure 5, two arrays 20 and 21 are shown in a parallel linear pattern. The vessel 18 lays both arrays 20 and 21 on the sea floor and then generates seismic source signals in a particular pattern above the arrays 20 and 21. Once the data is collected for this location, the vessel 18 then drags the arrays
  • each array 20a and 21a are attached to arrays 20b and 21b by a mechanical connection 50 sufficient to take the loads associated with dragging the entire length.
  • the buoys 16 for recording in this embodiment are not for redundancy. Rather, each buoy transmit and/or records signals from its associated section of the array. It will be understood by those of skill in the art, based upon review of the present disclosure, that redundancy is provided in further embodiments by addition of further buoys. It will also be appreciated that, although only two multiple portion arrays 20 and

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  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Geology (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Environmental & Geological Engineering (AREA)
  • Oceanography (AREA)
  • Remote Sensing (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Testing Or Calibration Of Command Recording Devices (AREA)

Abstract

L'invention porte sur un dispositif permettant d'effectuer un relevé sismique en milieu océanique, lequel dispositif comporte un câble (17) pourvu de capteurs (13) de signaux sismiques. Ce câble (17) comporte une partie servant à la détection (11) reposant sur les fonds océaniques (15), une partie avant (12) attachée à une première extrémité de la partie de détection (11) et une bouée (16) attachée à la seconde extrémité de la partie avant (12) du câble. Le câble (12) est suspendu à cette bouée (16) depuis la surface et un navire (18), une fois le câble posé sur les fonds océaniques, produit des signaux sismiques source.
PCT/US1997/014362 1996-08-12 1997-08-12 Navire pourvu d'un dispositif trainant monte en serie et technique d'exploitation correspondante WO1998007050A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU40680/97A AU4068097A (en) 1996-08-12 1997-08-12 Single vessel dragged array system and method for operation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US69592096A 1996-08-12 1996-08-12
US08/695,920 1996-08-12

Publications (1)

Publication Number Publication Date
WO1998007050A1 true WO1998007050A1 (fr) 1998-02-19

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6483776B1 (en) 1998-11-13 2002-11-19 Arne Rokkan Seismic cable with sensor elements being heavier than the cable
US6932185B2 (en) * 2002-08-22 2005-08-23 Institut Francais Du Petrole Acquisition method and device for seismic exploration of a geologic formation by permanent receivers set on the sea bottom
US9195783B2 (en) 2010-08-16 2015-11-24 Exxonmobil Upstream Research Company Reducing the dimensionality of the joint inversion problem
US9453929B2 (en) 2011-06-02 2016-09-27 Exxonmobil Upstream Research Company Joint inversion with unknown lithology
US9494711B2 (en) 2011-07-21 2016-11-15 Garrett M Leahy Adaptive weighting of geophysical data types in joint inversion
US9702995B2 (en) 2011-06-17 2017-07-11 Exxonmobil Upstream Research Company Domain freezing in joint inversion
US9829594B2 (en) 2003-05-30 2017-11-28 Fairfield Industries, Inc. Ocean bottom seismometer package
US9846255B2 (en) 2013-04-22 2017-12-19 Exxonmobil Upstream Research Company Reverse semi-airborne electromagnetic prospecting
US10379255B2 (en) 2010-07-27 2019-08-13 Exxonmobil Upstream Research Company Inverting geophysical data for geological parameters or lithology
US10591638B2 (en) 2013-03-06 2020-03-17 Exxonmobil Upstream Research Company Inversion of geophysical data on computer system having parallel processors
WO2020236008A1 (fr) * 2019-05-22 2020-11-26 Equinor Energy As Système d'acquisition de données sismiques

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US2729300A (en) * 1949-11-29 1956-01-03 Marine Instr Company Water borne means for making seismic surveys
US4450543A (en) * 1982-03-19 1984-05-22 Mobil Oil Corporation Sectionalized marine seismic cable
US4516227A (en) * 1981-12-04 1985-05-07 Marathon Oil Company Subocean bottom explosive seismic system
US4942557A (en) * 1983-05-18 1990-07-17 Shell Oil Company Marine seismic system
US4970696A (en) * 1988-07-13 1990-11-13 Atlantic Richfield Company Method for conducting three-dimensional subsurface and marine seismic surveys
US5010531A (en) * 1989-10-02 1991-04-23 Western Atlas International, Inc. Three-dimensional geophone
US5113377A (en) * 1991-05-08 1992-05-12 Atlantic Richfield Company Receiver array system for marine seismic surveying

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2729300A (en) * 1949-11-29 1956-01-03 Marine Instr Company Water borne means for making seismic surveys
US4516227A (en) * 1981-12-04 1985-05-07 Marathon Oil Company Subocean bottom explosive seismic system
US4450543A (en) * 1982-03-19 1984-05-22 Mobil Oil Corporation Sectionalized marine seismic cable
US4942557A (en) * 1983-05-18 1990-07-17 Shell Oil Company Marine seismic system
US4970696A (en) * 1988-07-13 1990-11-13 Atlantic Richfield Company Method for conducting three-dimensional subsurface and marine seismic surveys
US5010531A (en) * 1989-10-02 1991-04-23 Western Atlas International, Inc. Three-dimensional geophone
US5113377A (en) * 1991-05-08 1992-05-12 Atlantic Richfield Company Receiver array system for marine seismic surveying

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6483776B1 (en) 1998-11-13 2002-11-19 Arne Rokkan Seismic cable with sensor elements being heavier than the cable
US6932185B2 (en) * 2002-08-22 2005-08-23 Institut Francais Du Petrole Acquisition method and device for seismic exploration of a geologic formation by permanent receivers set on the sea bottom
US10557958B2 (en) 2003-05-30 2020-02-11 Magseis Ff Llc Ocean bottom seismometer package
US9829594B2 (en) 2003-05-30 2017-11-28 Fairfield Industries, Inc. Ocean bottom seismometer package
US9829589B2 (en) 2003-05-30 2017-11-28 Fairfield Industries, Inc. Ocean bottom seismometer package
US11237285B2 (en) 2003-05-30 2022-02-01 Magseis Ff Llc Ocean bottom seismometer package
US10422908B2 (en) 2003-05-30 2019-09-24 Magseis Ff Llc Ocean bottom seismometer package
US10539696B2 (en) 2003-05-30 2020-01-21 Magseis Ff Llc Ocean bottom seismometer package
US10379255B2 (en) 2010-07-27 2019-08-13 Exxonmobil Upstream Research Company Inverting geophysical data for geological parameters or lithology
US9195783B2 (en) 2010-08-16 2015-11-24 Exxonmobil Upstream Research Company Reducing the dimensionality of the joint inversion problem
US9453929B2 (en) 2011-06-02 2016-09-27 Exxonmobil Upstream Research Company Joint inversion with unknown lithology
US9702995B2 (en) 2011-06-17 2017-07-11 Exxonmobil Upstream Research Company Domain freezing in joint inversion
US9494711B2 (en) 2011-07-21 2016-11-15 Garrett M Leahy Adaptive weighting of geophysical data types in joint inversion
US10591638B2 (en) 2013-03-06 2020-03-17 Exxonmobil Upstream Research Company Inversion of geophysical data on computer system having parallel processors
US9846255B2 (en) 2013-04-22 2017-12-19 Exxonmobil Upstream Research Company Reverse semi-airborne electromagnetic prospecting
WO2020236008A1 (fr) * 2019-05-22 2020-11-26 Equinor Energy As Système d'acquisition de données sismiques

Also Published As

Publication number Publication date
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