Abstract:
A seismic sensor unit (10) comprises a case (12) containing electronic circuits (18, 20) that serve to digitise and digitally process the output signals of a seismic sensor element (16) inside the case (12). A first digital filtering of acquired signals can be provided at sensor unit level before the data are further fed into a seismic network and further processed.
Abstract:
A method of computing the location of air guns and hydrophones within a seismic spread utilizes a navigation network having a plurality of stations. The network provides a plurality of navigation observations. A number of the observations consist of magnetic bearings which are used to derive the hydrophone locations. The method includes the steps of: a) obtaining a set of observations from the network, each observation being obtained by using navigation devices whose origin system moves independent of the navigation reference point; and b) forming a design matrix wherein the magnetic bearings are modeled based on the equation (I).
Abstract:
A method of replacing an electronics module in a seismic cable on the open sea, (as well as a device for use in the replacing) where the replacement is carried out with the aid of a small boat equipped with cable rollers, the method comprising positioning the part of the cable including the electronics module on a first and a second cable roller respectively in such a way that the electronics module and its couplings are located between the two rollers, clamping the sections of cable on either side of the electronics module in a first and a second clamping arrangement (1, 2) respectively, with the clamping arrangements connected together via a mechanical tensioning device (3), moving the clamped sections of cable towards each other using the tensioning device in such a way that the tension in the seismic cable is taken up by the tensioning device, after which the electronics module can be removed and replaced after which the tensioning device (3) is slackened slightly and the clamping arrangement (1, 2) is released from the sections of cable before the part of the seismic cable with the new electronics module is replaced in the sea.
Abstract:
A method of computing the location of air guns and hydrophones within a seismic spread utilizes a navigation network having a plurality of stations. The network provides a plurality of navigation observations. A number of the observations consist of magnetic bearings which are used to derive the hydrophone locations. The method includes the steps of: a) obtaining a set of observations from the network, each observation being obtained by using navigation devices whose origin system moves independent of the navigation reference point; and b) forming a design matrix wherein the magnetic bearings are modeled based on the equation (I).
Abstract:
Devices for handling, i.e. paying out, towing and raising linear acoustic antennas towed behind ships, are disclosed. A solely mechanical auxiliary raising cable (103) is provided for winding the electrical connecting cable (106) and the antenna (102) itself onto a winch (104) without having to disconnect the electrical cable at any point. Short circuits and faulty contacts are thus avoided in the cable connections.
Abstract:
A towed streamer including buoyant core (1), and strength members (3) to transmit tension along the streamer. Strength members (3) are arranged so that the streamer is compliant for a predetermined elongation of the streamer. Members (3) are embedded in an inner jacket (5) surrounded by an outer jacket (6). The assembly is encased in an extruded outer jacket (2). Braided data bearers (4) can be provided between the inner jackets (5, 6). Strength members (3) can be braided with interstices impregnated with gel. Where the strength members (3) are of non-compliant material, the braid is initially compliant where the streamer is slightly elongated but becomes non-compliant as the streamer elongates further. Alternatively a combination of compliant (3) and non-compliant members (14) can be used where the compliant members (3) only become engaged after a predetermined elongation of the streamer.
Abstract:
Embodiments included herein are directed towards a marine seismic streamer. The seismic streamer may include an outer skin formed in a longitudinally extending tubular shape, an inner surface of the outer skin defining an internal volume containing a gel substance. The seismic streamer may also include a plurality of micro-electro-mechanical ("MEMS") sensors and a plurality of hydrophones associated with the outer skin, wherein the plurality of MEMS sensors are spaced non-uniformly in the seismic streamer along an axial direction of the streamer, such that not more than 100 MEMS sensors are located in the seismic streamer over a continuous 100 meter axial length of seismic streamer. The seismic streamer may further include an electronics system extending axially through an inside portion of the outer skin and a strength member core extending axially through an inside portion of the outer skin.
Abstract:
A seismic deployment system having a deployment apparatus, a tow line, and a carrier line having a plurality of seismic sensor coupled therealong. The deployment apparatus has a hydrodynamic body. The tow line is configured for towing the hydrodynamic body through a water column. The carrier line is engaged with the deployment apparatus. The deployment apparatus is configured to control tension in the carrier line for deployment of the seismic sensors while the hydrodynamic body is towed through the water column by the tow line.
Abstract:
A seismic streamer can include an outer tube that defines an interior space having a longitudinal axis; sensor packages disposed in the interior space at respective positions along the longitudinal axis; a rope disposed in the interior space and offset from the longitudinal axis; and gel filled foam disposed in the interior space at least in part between the sensor packages and at least in part about portions of the rope where the gel filled foam includes a water swellable material that, responsive to a breach in the outer tube and contact with water, transitions the gel filled foam from an unswollen state to a swollen state that hinders gel leakage from the breach in the outer tube.
Abstract:
A front-end gear (608) connects a streamer (604) to a vessel (600). The front-end gear (608) includes a lead-in (614) that connects to the streamer (604), a first bend limiting element (636) attached to the lead-in and to a float (630) that floats at a sea surface, a second bend limiting element (660) attached to the lead-in, a distance L away from the first bend limiting element (636), and a depressor (662) attached to the second bend limiting element (660). The float (630) generates a first force (F1) on the lead-in and the depressor generates a second force (F2) on the lead-in when the lead-in is towed underwater. The first and second forces act to apply a tension in a portion of the lead-in spanning the distance L, to reduce transversal noise propagation toward the streamer.