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AssigneeInstitut Francais du Petrole
InventorRenate Bary
Estimating the term…
System designed for acquisition of seismic data by means of acquisition stations set on the bottom of a water mass. The system comprises bottom acquisition stations (DSAU) combining a streamlined boom suited to stick into the bottom and thus to couple several seismic receivers with the underlying formation, and a scaled body for electronic data acquisition and communication modules. These acquisition stations (DSAU) are put into water and go down to the bottom under the effect of gravity. Several relay buoys (RCB) are positioned at the surface, each with a GPS positioning module, a radio link with a central station (CCRU), on a ship for example, and modules intended for acoustic communication with bottom acquisition stations (DSAU), used both to determine the position of these stations in relation to the relay buoys and to exchange control data and seismic data (good running order data or possibly seismic traces acquired if the conditions lend themselves thereto). Application: seismic prospecting or monitoring of an underground formation.
1) A system intended for acquisition of seismic data relative to a subsea underground formation, comprising a central control and acquisition station (CCRU), several relay buoys (RCB) suited to float on the surface of the water and comprising S each a control module (CPU), a positioning signal receiver (Rx) using GPS type satellite positioning for example, and radio transmission means (VHF) for exchanging data with central control and acquisition station (CCRU), a plurality of bottom seismic acquisition stations (DSAU) comprising each a sealed body including a pressure detector (PS) and associated with a streamlined part or boom provided with a housing for seismic receivers (SRU), suited to descend under the effect of gravity to the bottom of the water mass and to enter it so as to couple seismic receivers (SRU) with the underground formation, each acquisition station (DSAU) comprising a control unit (UC), and a device (DAM) intended for acquisition of seismic data received by seismic receivers (SRU) in the boom and by pressure detector (PS), characterized in that the relay buoys and bottom seismic acquisition stations (DSAU) are each provided with an acoustic transmission device including an acoustic transponder (AT), an acoustic positioning module (PLM) and an acoustic communication module (ACM) for exchanging therewith, by modem via transponder (AT), either positioning data or control data from central station (CCRU) or seismic data acquired by the acquisition device, to be transmitted to said central station (CCRU).
5) A system as claimed in any one of the previous claims, characterized in that each acquisition station (DSAU) comprises means for optical transmission of the seismic data recorded to a relay buoy (RCB) or a vehicle.
6) A system as claimed in any one of the previous claims, characterized in that each relay buoy (RCB) comprises means (PLM, VHF) cooperating with control module (CPU) for acquiring and dating the acoustic signals relative to the positioning of acquisition stations (DSAU) and for transmitting them to central station (CCRU) at the same time as its own coordinates received by receiver (Rx) of the satellite positioning system.
7) A system as claimed in any one of the previous claims, characterized in that each relay buoy (RCB) comprises means (COM) for recording acquired seismic data coming from acquisition stations (DSAU) and for transmitting them to central control and recording station (CCRU).
8) A system as claimed in any one of the previous claims, characterized in that each relay buoy comprises means for managing transmission of the signal intended to trigger a seismic source in order to best synchronize acquisition of the seismic data by bottom stations (DSAU).
9) A system as claimed in any one of the previous claims, characterized in that each acquisition station (DSAU) comprises buoyancy means (4) associated with sealed body (1) and launching means (3) for disconnecting said body (1) from the corresponding boom (2) at the command of central station (CCRU).
10) A system as claimed in any one of the previous claims, characterized in that each acquisition station (DSAU) comprises coupling means for coupling to an industrial transmission network, allowing direct transfer of the stored seismic data to the central station.
11) A system as claimed in any one of the previous claims, characterized in that central station (CCRU) comprises a control set (UC) including a central unit (CPU) associated with storage means (ME), and interface elements that manage exchanges between central unit (CPU) and a graphics interface that manages exchanges with visual display and printing means (IGO, PR/PL), mass storage means (DD, CD, BM), and means (FSI, NI) for communication with acquisition stations (DSAU) and relay buoys (RCB), sets (E1, E2) allowing communication with the relay buoys by radio link and reception of positioning signals by satellite, and a set (E3) intended to control and trigger a seismic source (SS).
12) A system as claimed in any one of the previous claims, characterized in that it comprises a portable control and testing station (PTCU) ensuring deployment and recovery of the acquisition stations and of their data, including means for locating acquisition stations (DSAU) after they have returned to the surface by means of a radio link, means for downloading data stored in acquisition stations (DSAU) and for recording them, means for remote recovery of seismic data stored in relay buoys (RCB), and means for transferring the seismic data to central control and recording station (CCRU) by means of a communication network.
13) A method intended for seismic exploration or monitoring of a subsea underground formation, comprising:
14) A method as claimed in the previous claim, characterized in that it comprises positioning and initial time synchronization of each bottom seismic acquisition station (DSAU) as it is put into water, by reference to a satellite positioning system, and monitoring of its descent down to the bottom by combination of time synchronization data and of time measurements obtained by acoustic telemetry between the acquisition station and the various relay buoys, until stabilization of said station in contact with the bottom.
15) A method as claimed in any one of the previous claims, characterized in that it comprises acoustic transmission of seismic record traces picked up by the seismic receivers of each acquisition station to the corresponding relay buoy by means of said corresponding sets.
16) A method as claimed in any one of the previous claims, characterized in that it comprises acoustic transmission from each acquisition station to the corresponding relay buoy, by means of said corresponding sets, of quality data indicative of the good working order of each acquisition station.
Dependencies are inferred from the claim text.