Abstract:
Walkaway vertical seismic profiling is conducted in a body of water. A marine seismic cable is positioned substantially vertically in a body of water. The cable has a number of hydrophones spaced along its length. A seismic source is moved along a line of traverse past the seismic cable and is periodically activated to emit acoustic waves. The response of the hydrophones to reflection of the acoustic waves from subsurface formations is then recorded for processing and analysis.
Abstract:
A seal of flexible waterproof material joins two shells, or a shell and its end plate, which are spaced at their edges to have a separation or gap between them into which the seal material loops. The seal material is attached to each shell, or to the shell and its end plate, to effect a watertight seal at the joint. When one joint edge moves radially with respect to the other edge, a low friction rolling action of the seal material accommodates the motion with low frictional resistance and low energy loss.
Abstract:
A marine seismic streamer having a plurality of seismic recovery units spaced along the length thereof. Each unit includes an inflation flotation device that will deploy when the streamer sinks to a trigger depth which is continuously adjusted in response to the actual operating conditions at the time.
Abstract:
A towed piezoelectric cable having a plurality of receiver element units which are arranged on a nonshrinking flexible core with leaving a buffer zone therebetween, each of said receiver element units having two piezoelectric elements which are polarized in a predetermined direction, and are provided with inner electrodes connected to each other and outer electrodes between which an output signal is produced, respectively, the assembly of said receiver element units and said flexible core being contained in a flexible tube which is filled with an insulating oil.
Abstract:
A seismic streamer retrieval system utilizes an inflatable bag to lift the streamer to the water surface where it can easily be recovered. An acoustical signal or a pressure switch is used to activate said device so as to cause the inflatable bag to be ejected from said device and inflated to lift the streamer to the water surface. A small electric motor and drill bit are used to puncture a gas cylinder to release gas into the inflatable bag.
Abstract:
A marine seismic streamer employs a plurality of sections connected together sequentially with fluid blocking connectors. Each section contains a plurality of groupings of hydrophones with the hydrophones within each grouping connected together to provide a single seismic signal output for such groupings. The two terminal groupings of each section have variable hydrophone densities along their lengths so as to discriminate against noise generated in the streamer by the action of the fluid blocking connectors in producing pressure waves in the fluid fill within the streamer.
Abstract:
A spacer for a marine seismic streamer employs a compliant material that mechanically isolates the spacer from the hosewall and strain members of the streamer and also allows the flow of fill fluid therethrough so as to prevent pressure pulse build-up in such fluid during towing of the streamer along a line of exploration.
Abstract:
A hydrophone mount for use with a marine streamer cable having solid foam flotation. The mount comprises a semicylindrical housing having a cavity formed on its outer surface for receiving the hydrophone. The hydrophone is mounted in the recess and the voids filled with an acoustic responsive material. The mount is positioned in a semicylindrical recess formed in the stream cable coaxially with the center of the cable. The stress member and electrical conductors are located at the center of the streamer cable.
Abstract:
A technique for a vibration isolation module (VIM) used for towed arrays is disclosed. The VIM has a stretchable cable on which is mounted one or more rigid spacers which make contact with an outer hose formed of a flexible material having a selected vibration attenuation characteristic. The spacer transmits energy between the parts of the VIM which contact the spacer for attenuation purposes. The spacer is "soft mounted" on the stretchable cable so that it may be moved by a limited amount along the cable in response to forces of a specified minimum magnitude. This ability to move allows adjustment of the internal parts of the VIM during use to avoid concentrating stress at any one particular contacting area. Disclosed is an embodiment where two sleeves are used to abut the spacer at opposing ends thereof. The sleeves are clamped to the stretchable cable with a limited clamping force such that they remain stationary until the spacer is exposed to the predetermined breakaway force and/or the stretchable cable cross-sectional size decreases by a predetermined amount.
Abstract:
A composite layered assembly of piezoelectric polymer layers and printed wiring layers are configured so that plated-through holes make electrical connection from the outputs of a plurality of polymer hydrophones formed on one or more polymer layers to a plurality of output conductors on a single plane after each hydrophone output is amplified in its associated amplifier.