Abstract: Methods and apparatus for acquiring seismic data using a seabed seismic data cable positioned on a seabed are described, one method including deploying a seabed seismic cable, the cable comprising two or more active sections separated by at least one jumper section; and acquiring seabed seismic data using the seabed seismic cable. Certain methods include analyzing spacing needed between active sensor units in the active sections prior to deploying the seabed seismic cable, and selecting a length of the jumper section based on the analysis. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: Methods and apparatus for acquiring seismic data using a seabed seismic data cable positioned on a seabed are described, one method including deploying a seabed seismic cable, the cable comprising two or more active sections separated by at least one jumper section; and acquiring seabed seismic data using the seabed seismic cable. Certain methods include analyzing spacing needed between active sensor units in the active sections prior to deploying the seabed seismic cable, and selecting a length of the jumper section based on the analysis. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: Apparatus and methods for acquiring seismic data using a seabed seismic data cable positioned on a seabed are described, including controlling effect of water flow on the cable during data acquisition using fairing elements, which may be caused to extend from the cable generally transversely as water flows past the cable. Alternate paths for water underneath the cable may also be provided, reducing lift forces on the cable. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: Apparatus and methods for acquiring seismic data using a seabed seismic data cable positioned on a seabed are described, including correcting for the effect of one or more sensor non-linear motions, which improves accuracy of seismic data. One or multiple non-linear movements of the sensor may be corrected for. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A method for computing a pressure signal gradient. The method includes recording a plurality of pressure signals at at least one of a first receiver and a second receiver. The first receiver and the second receiver are disposed within a cluster. The method further includes recording a plurality of pressure signals at the second receiver; computing a calibration filter for removing the difference in distortions between the pressure signals recorded at the first receiver and the pressure signals recorded at the second receiver; and computing the pressure signal gradient between the pressure signals recorded at the first receiver and the pressure signals recorded at the second receiver using the calibration filter.

Abstract: The present invention provides a coupling device (300). The coupling device includes a collar (315, 405) defining an opening tberethrough to receive a seismic sensor (305) such that the collar (315, 405) permits rotation about the seismic sensor (305) and at least three extensions (320, 410) from the collar, the extensions (320, 410) being capable of rotating with the collar (315, 405) such that any two of them may couple to the ground.

Abstract: A method of matching the impulse response of a hydrophone and the impulse of a geophone accelerometer comprises perfroming a calculus operation upon the response of one of the hydrophone and the accelerometer. A filter is then derived from the output of the calculus operation and the response of the other of the hydrophone and the accelerometer. The filter may then be used to match seismic data acquired by the one of the hydrophone and the accelerometer to seismic data acquired by the other of the hydrophone and the accelerometer. The calculus operation may comprise differentiating the hydrophone response, or integrating the accelerometer impulse response.

Abstract: A method of performing a seismic survey of a hydrocarbon reservoir in the earth formations beneath a body of water includes deploying a seismic cable from a drum carried by a remotely operated vehicle on the seabed. The cable is deployed into a lined trench, which is formed either concurrently with cable deployment or during a previous survey, to ensure good repeatability of successive surveys of the reservoir, in order to enable changes in characteristics of the reservoir, eg due to depletion, to be monitored.

Abstract: A seismic cable (110) and a method for producing a seismic cable are disclosed. The seismic cable (110) comprises a sensor module (130); at least one lead (210) to or from the sensor module (130); a stress member (225) extending continuously through the sensor module (130); and a sheath (230) enclosing the leads (210) and the stress member (225), the sheath (230) terminating at each end of the sensor module (130), and at least one mechanical guide (240) in the sensor module (130) deflecting the stress member (230). The method comprises providing a cable core including a stress member (225) and a lead (210); enclosing the cable core in a sheath (230); providing an opening in the sheath (230); and assembling a sensor module (130) to the cable core over the opening such that the stress member (225) extends continuously through the sensor module (130).

Abstract: A method of performing a seismic survey of a hydrocarbon reservoir in the earth formations beneath a body of water includes deploying a seismic cable from a drum carried by a remotely operated vehicle on the seabed. The cable is deployed into a lined trench, which is formed either concurrently with cable deployment or during a previous survey, to ensure good repeatability of successive surveys of the reservoir, in order to enable changes in characteristics of the reservoir, eg due to depletion, to be monitored.

Abstract: A housing for a seismic sensing element (3) for use on the earth's surface comprises connecting means (5) for connecting the housing (3) to a support cable (2) so as to allow relative movement between the sensor housing (3) and the cable (2). This de-couples the sensor housing from the support cable, and improves the fidelity of the sensor. The connecting means (5) preferably comprises resilient connecting elements, to prevent the transmission of vibrations between the support cable and the sensor housing. The sensor housing (3) preferably has a flat base (1), so that there is good coupling between the sensor housing and the earth. Alternatively, the sensor housing can be fitted with a base member ((24a, 24b, 24c) that has at least one flat face (26, 26a, 26b, 26c).

Abstract: A method of performing a seismic survey of a hydrocarbon reservoir in the earth formations beneath a body of water includes deploying a seismic cable from a drum carried by a remotely operated vehicle on the seabed. The cable is deployed into a lined trench, which is formed either concurrently with cable deployment or during a previous survey, to ensure good repeatability of successive surveys of the reservoir, in order to enable changes in characteristics of the reservoir, eg due to depletion, to be monitored.

Abstract: A method of performing a seismic survey of a hydrocarbon reservoir in the earth formations beneath a body of water includes deploying a seismic cable from a drum carried by a remotely operated vehicle on the seabed. The cable is deployed into a lined trench, which is formed either concurrently with cable deployment or during a previous survey, to ensure good repeatability of successive surveys of the reservoir, in order to enable changes in characteristics of the reservoir, eg due to depletion, to be monitored.

Abstract: The present invention provides for cable motion detection. In one aspect of the instant invention, a method is provided for cable motion detection using orientation sensor. The method includes determining at least one initial inclination of at least one orientation sensor coupled to a seismic cable, determining at least one current inclination of the at least one orientation sensor, and determining whether the at least one seismic cable has moved from the at least one initial inclination and the at least one current inclination.

Abstract: A method of performing a seismic survey of earth formations beneath a body of water is disclosed. The method includes: (a) deploying a seismic cable having a plurality of seismic sensors distributed therealong in close proxmity to elongate locating means provided at the bottom of the body of water; (b) operating an acoustic source in the body of water to produce seismic signals which enter the formations; (c) detecting seismic signals which return from the formations with said sensors; and (d) removing the seismic cable from the bottom of the body of water.

Abstract: A housing for a seismic sensing element (3) for use on the earth's surface comprises connecting means (5) for connecting the housing (3) to a support cable (2) so as to allow relative movement between the sensor housing (3) and the cable (2). This de-couples the sensor housing from the support cable, and improves the fidelity of the sensor.

Abstract: A method of performing a seismic of a hydrocarbon reservoir in the earth formations beneath a body of water includes deploying a seismic cable from a drum carried by a remotely operated vehicle on the seabed. The cable is deployed into a lined trench, which is formed either concurrently with cable deployment or during a previous survey, to ensure good repeatability of successive surveys of the reservoir, in order to enable changes in characteristics of the reservoir, eg due to depletion, to be monitored.