Seismic streamer construction for minimizing hydrophone response to vibration produced pressure fields

Claim 1

A marine seismic streamer section for an elongated seismic streamer made up of plural sections serially connected together, the streamer section comprising an elongated streamer jacket of generally cylindrical tubular configuration of predetermined inner and outer diameter concentric with a streamer axis including signal wires and strain cables extending thrOugh the interior thereof, an array of hydrophone units in the streamer section arranged in closely adjacent pairs of associated hydrophone units to respond to accoustic pressure variations originating externally of the streamer section and produce electrical output signals, means connecting the output signals from each associated pair of hydrophone units in additive relation to provide an added pair output; and means supporting the hydrophone units of each associated pair within said jacket in a manner to effect cancellation in the added pair output from the pair of associated units of unwanted output signals resulting from sound pressure fields produced by vibratory motion of the components forming the streamer section, comprising a pair of cylindrical bodies forming piston members concentric with said streamer axis having an outer diameter corresponding substantially to the inner diameter of said jacket tightly fitted therein and having apertures therethrough through which said strain cables and signal wires pass in tightly fitted relation, sealing means substantially sealing said piston members against the surfaces of said wires and cables and against said jacket to substantially prevent leakage of sound pressure fields travelling in the streamer section into the space between the associated pair of piston members, means firmly securing said piston members to said strain cables passing therethrough, and a pair of spaced hydrophone mounting members fixedly located in said space between the pair of piston members fixed on mounting faces of said respective piston members of said pair transverse to said streamer axis which face inwardly toward said space and confront each other, said mounting members supporting said hydrophone units in fixed spaced relation to their associated mounting faces of the piston members, whereby motion imparted to said mounting faces caused by vibratory motion of the streamer components is substantially identical in phase, amplitude and frequency at both faces producing identical sound fields of opposite sign which activate the pair of hydrophone units to produce opposite sign signals which cancel each other in said added output, each of said mounting members being a rigid body having a cylindrical cup-shaped portion spaced from the mounting face of the supporting piston and encircling the associate hydrophone unit in peripherally supported relation therein at the axial center thereof and having sound pressure communicating apertures in the end wall more remote from the associated mounting face, and said rigid body including plural legs extending integrally from the cup-shaped portion in concentric parallelism with the streamer axis to the associated mounting face and being fastened rigidly thereto.