Abstract: A system for selectively tuning the buoyancy of a marine seismic streamer or underwater cable. Trimming weights are positioned along the streamer cable and can be integrated within a solid buoyancy member or can be located within an outer streamer sheath. The weights overcome the flotation forces provided by an internal buoyancy section to control the elevation of the streamer section. The outer streamer sheath can be opened to permit the removal or addition of trimming weights to the streamer section, and can be resealed to prevent water from intruding into the streamer interior. A single trimming weight can be positioned along the buoyancy member, or a plurality of trimming weights can be used. The trimming weights permit a tight buoyancy range to be accomplished without increasing water drag forces or noise as the streamer is towed.

Abstract: A well tool in accordance with the invention comprises an attenuation device which attenuates tube waves associated with an elastic wave emission and/or reception set (1, 12). The attenuation device comprises a bubble generator (2) which releases into the well a gas not readily soluble in the well fluid, slightly overpressured in relation to the hydrostatic pressure, in the form of calibrated bubbles which greatly attenuate the parasitic tube waves. The attenuation device is placed above or below the elastic wave emission and/or reception set having a plurality of pickups whose signals are acquired by a local electronic module (14) and/or a source of elastic waves such as a vibrator. A bubble trap (17) is preferably associated with the bubble generator (2) in order to limit the volume of gas to be generated in situ. The invention is applicable to VSP type seismic prospecting and acoustic logging.

Abstract: A system and method for periodically providing information about subsurface formations in a marine environment using a non-towed seismic signal source (3) and a static array of seismic signal receivers (4) is disclosed. The seismic signal source (3) comprises a support frame (10) and a line (7) attaching the support frame to a stationary platform (2), wherein the line (7) restrains the support frame (10) in a position that is static in relation to the formation (8). The seismic signal source (3) includes eight air guns (12) attached to the support frame (10) such that the air guns (12) are discharged to provide a tapered, heavy centered, point source seismic signal at a specific location relative to the formation (8) that is reflected to the static array of seismic signal receivers (4) such that changes in the formation characteristics may be observed over time.

Abstract: A marine seismic cable system for marine surveying comprises an electrical conductor within a tubing for conveying compressed air and electricity between a seismic vessel and equipment such as air guns. The tubing resists elongation caused by water drag forces acting against the tubing exterior surface and provides a protective shield to the enclosed electrical conductor or conductor bundle. This combination uniquely conveys compressed air and electricity while significantly reducing the outside cable diameter to reduce the weight and drag forces acting on the cable system. The combination also permits repair and replacement of the tubing or electrical conductor independent of the other component.

Abstract: A magnetic drive device couples the drive motor of a depth control device or bird, with the axle of the depth control wings. The magnetic drive includes a plurality of permanent magnet pieces mounted in respective drive blocks on either side of a magnetically permeable membrane of the main body of the drive mechanism. The magnet pieces are mounted side by side in alternating polarity to capture as much of the magnetic flux of the magnets as possible to minimize stray flux from escaping the drive. Pole pieces either side of the drive blocks also serve to capture stray flux. To the maximum extent possible within the constraints of mechanical durability, the drive mechanism is made of non-magnetic or non-ferrous materials which would interfere with the heading sensor of the bird. Thus, this invention avoids reducing the accuracy of the heading sensor of the bird, while eliminating a major source of seawater inleakage into the bird.

Abstract: The present invention discloses a marine seismic system with a control system and at least one powered (manned or unmanned) tow vehicle with at least one seismic apparatus or system attached thereto, the at least one powered tow vehicle for selectively towing under its own power the at least one seismic apparatus or system. In one aspect such towing is done in controlled conjunction with movement of one or more host vessels. In another aspect such a marine seismic system includes at least one service boat for servicing the at least one powered tow vehicle.

Abstract: Device for the adjustment of buoyancy of a seismic cable comprising a main part (1) adapted to firm, integrated mounting into a chosen point in the length of the cable, the main part (1) comprising fastening means (3,4) for one or more weight or buoyancy elements (2) and one or more exchangeable weight or buoyancy elements (2) adapted to being mounted into the main part (1).

Abstract: Sonar suspension apparatus comprising a flotation buoy and an underwater sonar array connected to the flotation buoy by a suspension cable, wherein the sonar array comprises a plurality of transducer-carrying elongate members including at least one rigid arm and at least one flexible line.

Abstract: A depth control device for an underwater cable includes a rotary actuator having a rotating output shaft connected to a swash plate. Rotation of the swash plate by the actuator causes a rocker arm to pivot about an axis transverse to the axis of the output shaft. The rocker arm is drivingly connected to a drive shaft for rotating wings about their pitch axes. The pitch axes of the wings can be perpendicular to and intersecting the axis of the actuator output shaft, enabling the depth control device to be extremely compact.

Abstract: A solid marine seismic cable assembly includes communication coil housings which clamp around a cable in a spaced-apart relationship. The cable has a central axis. Each housing contains at least two communication coils adapted for communicating with an adjacent external device. Two of the communication coils, whether or not adjacent to one another, are offset at least 90.degree. from each other about the axis of the cable. The external devices affix to the cable assembly in a spaced-apart relationship corresponding to the spaced-apart relationship of the communication coil housings. Each external device has a unit which communicates with the communication coil via magnetic induction signals.

Abstract: Methods, systems, and towing bridles, are provided to increase spread width, streamer separation, and number in marine seismic data acquisition. The invention is applicable for towing seismic equipment behind a marine seismic data equipment handling vessel along a data acquisition path, the system comprising: a deflector attached to a deflector line; an equipment handling vessel attached to the deflector; a deflector line pulling vessel attached to the deflector line; and the marine seismic data equipment attached to the deflector line.

Abstract: A method for controlling the position and shape of marine seismic streamer cables, whereby a plurality of real time signals from a marine seismic data acquisition system and a plurality of threshold parameters from an input device are received. The real time signals are compared to the threshold parameters to determine if the streamer cables should be repositioned. The streamer cables are repositioned when the real time signals exceed the threshold parameters.

Abstract: A depth control apparatus for seismic streamers, comprising a central unit adapted for inserted mounting in the streamer substantially in axial alignment with the streamer, a housing which can rotate about the central unit and carries at least one control wing being angularly adjustable about a transverse axis adapted to be substantially horizontal in operative position, and an electric motor for adjusting the angle of the control wing about the transverse axis. The motor is located in the central unit and is adapted to have its current supply through the streamer. The control wing is so arranged on the housing that the transverse axis in operative position runs underneath the central unit. A transmission mechanism for the angular adjustment of the control wing by means of the motor, comprises a slide member which can be moved in the axial direction of the central unit and preferably surrounds the central unit.

Abstract: The seismic profile system and method using vertical sensor arrays relate to obtaining a seismic profile under two highly reflective boundaries. The system includes a source of seismic energy disposed beneath the air/water boundary, a first pair of sensors arranged in vertical relation and spaced apart by a predetermined vertical spacing distance, and a second pair of sensors similarly situated and spaced from the first pair by a predetermined horizontal spacing distance. The first and second pairs of sensors are disposed below at least two highly reflective boundaries, which may be the air/water boundary and a mud/water boundary. According to the method, the source is moved between two points and data is collected from the first and second pairs of sensors.

Abstract: As a means for determining the preferred azimuthal alignment of a horizontal borehole, the reflection travel time vectors between an acoustic source and a plurality of equidistant seismic receivers are measured along a plurality of directional wavefield trajectories. The travel time vectors are resolved to measure the angular orientation of the strike of vertical stress patterns. The alignment of the horizontal borehole is directed perpendicularly to strike.

Abstract: A positioning device for seismic equipment which is towed by a seismic vessel is designed with a body part which is equipped with wings (7) and rudders (8, 6, 9, 5). For the control of wings (7) and rudders (8, 6, 9, 5) control means, preferably hydraulic or electrical means are used. The device further comprises a control unit for processing of signals which preferably operate exclusively on the basis of information from the vessel or the ship, instruments for use in the positioning of the device and a communication system for the communication between the vessel and the device and vice versa, preferably electrical, acoustic or optical. It is further equipped with attachment devices for one or more cables (26) and floats, which are preferably provided at the front of the device, and preferably in the vicinity of the wing's (7) attachment point to the device's body part as well as a power supply system.

Abstract: A marine seismic signal source apparatus and method that maximizes the usable acoustical (db) energy of the array signature in a lower frequency bandwidth. The apparatus forms a three dimensional 2.times.4.times.2 array having a plurality of 8 air guns of identical firing chamber size (10 cubic inch) operably arranged in pairs at different water depths. Firing of the guns in a top to bottom time delayed sequence shifts the frequency domain of the peak acoustical db signal to concentrate the usable seismic energy in the deeper earth formation penetrating range. The frequency boundaries of the bandwidth of the occurrence of the peak 6 db increment of acoustical power are lowered and compressed into a narrower bandwidth by the firing sequence.

Abstract: A marine seismic streamer cable retriever is activated promptly when the cable and its attached retriever exceed a pre-selected safe depth. In an alternative scenario, an electronics module in the cable retriever monitors the presence of through-cable communications traffic between a mother ship and the various sensors in the cable. If an interruption in communications traffic is detected, a clock starts a count-down and sends a warning to the operator aboard ship. At the end of a count-down period, absent prior operator intervention, the cable retriever is activated.

Abstract: A marine seismic bottom geophone anchor and coupling device comprising two rectangular fabric sections attached along their edges and along a plurality of lines between edges to form a plurality of pockets. The pockets are filled with a weighting material. Connecting means are provided so that when the combined fabric sections are wrapped around a marine seismic bottom geophone, it will be held in a generally cylindrical form to simultaneously anchor the geophones and associated cables at a desired marine bottom location, isolate the sensors from noise sources, and provide good coupling to the marine bottom for receiving desired seismic signals.

Abstract: A sensitive towed optical fiber sensor array 50, wherein the fiber sensors (60A-60N) are connected in parallel, and the optical fiber cable (34) is paid out from the towing ship at a velocity about equal to but opposite to the velocity of the towing ship. The fiber sensors (60A-60N) are immune to electromagnetic interference, and the output of the sensors can be isolated readily to the parallel hookup of the sensors. Turbulence and acceleration noise is greatly reduced due to the manner in which the fiber cable (34) is paid out, and crosstalk between sensors is eliminated.

Abstract: A method and device for operating special equipment provided in seismic cables, i.e., gun cables and streamers (2, 3) during seismic surveys at sea, whereby energy is supplied through wires (4), or wireless transmitting/receiving devices, to the equipment (B, C, D) in the cables, without this energy supply affecting the seismic surveys. In order to achieve this, low output energy (A) is supplied through wires (4, 17) to electrical units, such as a transformer (5) in a sealed chamber (9) used to charge batteries (6) in a separate sealed chamber (10) so that they can emit for brief periods sufficiently high outputs of energy in order to perform the necessary operation of the equipment such as motors (7) and fluid pumps ( 14 ) . Control devices ( 13 ) are provided where required for control of the operation.

Abstract: An acoustic emission system for seismic surveying at sea, for the purpose of emitting a soundwave in a given direction, the system comprising firstly a plurality of immersed sources mechanically connected to at least one float means and secondly a control circuit for controlling said sources and comprising a plurality of delay means suitable for applying respective phase delays to each of the sources, said delays being defined by a nominal phase law associated with said given emission direction. According to the invention, the system also includes at least two attitude sensors providing signals representative of the absolute position of at least two of said sources to correction means of said control circuit, said correction means providing each of said delay means with a signal for correcting the nominal phase law and representative of variations in the relative positions of the sources. This system has application to geological prospecting by seismic surveying at sea.

Abstract: For the balancing of seismic streamer cables (1) circular ring or sleeve-shaped weighted bodies are adjustably attached at desired intervals on the cable. The weighted bodies can be resilient for temporarily enlarging an opening (3) to receive the cable therethrough and for closing onto the cable in use, or can be circular cross-sectional bodies formed by two parts (4, 5, 4', 5') partially connected together by a single pin (6, 6') and fastened together by a spring pin (7) or hook-shaped pivoted lever (8) engageable with a retainer pin (10).

Abstract: A sonobuoy for forming a plurality of virtual vertical arrays, the sonobuoy aving means for receiving and expelling water to cause said sonobuoy automatically to descend and rise in a water environment, whereby to form sequentially a plurality of virtual vertical arrays.

Abstract: For confidently coupling towed external devices to a marine seismic cable, a latch mechanism having a novel swing plate to improve the adjustability of the mechanism and provide a positive, clearly visible indication of latched and unlatched conditions. The swing plate serves as an external linkage between a rotatable adjustment head for a locking pin and a translatable lever arm for a locking rod. The locking pin and the locking rod extend from a latch housing on a towed device, such as a cable-leveling bird, and engage with a keyhole slot in a locking collar on the streamer. The swing plate engages the adjusting head, which protrudes from a side of the housing, in a push-nut engagement.

Abstract: A reversible drive for a fish-finder apparatus includes a motor, a drive gear driven by the motor, a driven gear driven by the drive gear and a fish-finder drive shaft driven by the driven gear. The drive gear contains one or more actuator members which actuate a drive control member, such as a reverse polarity switch, during rotation of the drive gear. When actuated, the drive control member reverses the drive to the motor and thereby reverses the drive to the fish-finder. A display panel contains diode indicators which are illuminated in response to the movement of the fish-finder.

Abstract: In towing sources of seismic energy behind a vessel, especially in connection with seismic surveys in waters which are covered with ice, the buoyancy floats and also the sources of seismic energy are readily influenced by broken up ice collecting behind the icebreaking towing vessel. In order to stabilize the tow of sources of seismic energy a towing line (7) is secured between the buoyancy means (4) belonging to the tow of sources of energy (3) and the vessel (1) at a point (10) which is located in the area of the waterline, so that towing line (7) will extend in the area of the waterline. Another towing line (8) is connected directly with the array of sources of seismic energy (5) and is secured to a towing point (11) on the vessel (1) located below the waterline. An arrangement is also disclosed for securing the towing line (8) in a suitable location to avoid influence from ice and, furthermore, the design of floats (4) avoids influence from the ice.

Abstract: The invention provides a seismic transmitter source system which includes a floatation device that contains a plurality of air tight chambers in a serial connection. A separate one way check valve is placed between each adjacent pair of the chambers. Pressurized air is continuously supplied to an end chamber. The one-way check valves enable the air to pass to the remaining chambers in one direction. A transmitter subarray containing a plurality of spaced apart transmitters is suspended from the floatation device by means of severasl pivotly connected links. The front end of the transmitter array is connected to a point near the front end of the floatation device. During operation, the seismic transmitter source system is pulled from a tow point located at the front of the floatation device, pulling both the floatation device and the transmitter subarray in substantially a horizontal straight line position while maintaining the transmitter subarray at a near constant depth below the water surface.

Abstract: In seismic surveys at sea a system for maintaining the sources of seismic energy (2) at the same level when emitting their signals includes sensors (5) provided close to the sources of energy (2) for emitting signals representing pressure conditions and/or motion transmitted to a control unit (9). These signals are compared by control unit (9) for controlling driving devices (6) for the suspension lines (3) for the sources of seismic energy (2), so that their distances from the surface of the sea may be controlled to keep all sources (2) at the same level.

Abstract: In seismic surveys in waters covered with ice, where seismic impulses are actuated under water and reflected signals are detected by a streamer cable (2) towed behind a vessel (1), in order to avoid the source of noise located outside the seismic system due to the icebreaking operation of the vessel (1) the vessel (1) is stopped during active survey and the streamer cable (3) is hauled in with a speed corresponding to the desired propulsion speed of the cable during detection. After detection the vessel again resumes ordinary operational speed and the streamer is paid out with a speed which maintains the desired advancing speed of the system.

Abstract: The present invention includes a buoy floating on a body of water. Positioning devices attached to the buoy are responsive to control signals to control the position of the buoy. A hydrone is suspended from the buoy to a predetermined shallow depth with an electrical cable and converts seismic waves to an electrical signal. A navigational device, on the buoy, provides position signals corresponding to the position of the buoy. A first transceiver with an antenna, receives first transmitted signals from a ship and provides them as control signals to the positioning devices. The first transceiver transmits signals corresponding to the seismic signal and to the position signals. A seismic device, located in the body of water, creates event in the body of water in response to a fire signal. Fire control apparatus located on the ship provides the fire signal to the seismic device.

Abstract: A mobile magnetometry processing system which scans an area in order to mure the magnetic field strength over the area, comprising:a plurality of N sensors for sensing the magnetic field of the area being scanned, each sensor generating an output signal, for example, a voltage, which is a function of the magnetic field it scans, the sensor being aligned in the general direction of the motion of the system;a plurality of N sets of means for weighting, for receiving and weighting the N signals from the means for sensing, each of the N sets comprising M weighting means;a plurality of M summers, each have N inputs, one from each of the N sets of means for weighting, for summing its N input weighted signals;a plurality of M filters each having an input which is connected to the output of a summer, for delaying the exit of an input signal by an amount of time equal to the time required for a sensor to advance the distance to the nearest adjacent sensor, the filtering process comprising a convolution;means, associat

Abstract: A method of marine seismic exploration of the strata beneath a body of water comprising the steps of generating a compressional wave in the body of water and sensing the converted shear waves reflected from the strata.

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 communication system for a seismic streamer by which all power and data signals are inductively coupled to the cable leveling devices or instrument pods disposed along the streamer cable. A high permeability ring of magnetic material is dispose around the streamer, and a coil is wound around a segment of the core and connected to circuitry within the bird. The coil can be part of a resonant circuit. Power signals transmitted along the streamer are inductively coupled via the ring core and associated coil to each bird to provide charging of a battery source in the bird. Control signals transmitted along the streamer are coupled via the ring core and coil to the electronics via the ring core and coil to the streamer for transmission to a receiving site. Alternative embodiments are also disclosed in which inductive coupling structures include a portion within the streamer in efficient coupling relationship for power and data transmission.

Abstract: In order to avoid noise and error-sources a marine streamer (3) for use in seismic exploration is provided with a buoyancy member (8) which is snake-shaped or tubular-shaped and slightly flexible and supports the active member (9) of the streamer by the aid of narrow suspension ropes (10). The streamer may be made adjustable as regards its height and it may be dividable into sections.

Abstract: A latching mechanism used to couple external devices to marine seismic streamer cables is disclosed. The latching device universally couples to collars predominantly used in the seismic industry. A mounting bracket or shank is provided which is coupled to the external device. The shank has a lug or finger fixed therein which extends from a mounting surface. Adjacent the lug is a latching device which is comprised of a cylinder having a cam defined at the upper end. The cylinder is recessed within the shank so that the cam and the lug are engaged with an aperture defined in the collars attached to the streamer cable. A lever extends from the cylinder through the exterior of the shank so that an operator may rotate the cylinder, turning the cam in the aperture to a locking position. A spring applies a tensile force to the cylinder, drawing the cam down against the aperature, and pulling the shank tight against the collar.

Abstract: A hydrostreamer includes connectors for joining to depending housings enclosing geophone sensors. These sensors are coupled to the bottom of the sea via such housings by the housings being appropriately weighted and externally surface serrated. Thus, the geophones detect s-waves directly from the ground in single-mode conversion fashion while simultaneously, hydrophones in the hydrostreamers detect p-wave reflections in traditional fashion.

Abstract: In order to accumulate data from which the signature of an array of n interacting seismic sources 21 to 27, for instance marine seismic sources in the form of air guns, can be determined, the array is actuated and the emitted pressure wave is measured at n independent points whose positions will respect to the array are known by hydrophones 31 to 37. Data from the measured pressure wave is stored for subsequent processing to produce n equivalent signatures of the n sources taking into account the interactions therebetween. The signature of the array is then determined merely by superposing the n equivalent signatures.

Abstract: Some of the laterally spaced air gun sub-arrays which are combined to form the sequentially fired source arrays of a marine prospecting system are shared between neighboring arrays. This double usage of said sub-arrays allows a larger number of full size arrays to be fired sequentially without requiring the deployment of additional sub-arrays which may exceed the capabilities of the towing vessel. In this way multiple profiles can be collected more efficiently in performing three-dimensional seismic surveys.

Abstract: A marine cable system including one or more elongated cable sections whose buoyancy may be independently controlled. Each section is associated with a pump and a variable volume, elongated bladder. In one embodiment, one reservoir containing buoyant fluid is included, and fluid from the reservoir is pumped between adjacent sections to inflate or deflate the associated bladders. In another embodiment, a rigid reservoir containing compressed gas is included in each section. The associated pump releases gas from the reservoir to inflate the bladder, or pumps gas from the bladder into the reservoir when desired. The pumps are operated in response to control signals from a remote control unit, such as one aboard a vessel towing the cable. One or more depth sensors may be attached in or near each section. Depth information from the sensors may be supplied to the control unit for use in generating the pump control signals. The buoyant fluid is entirely contained within the cable.

Abstract: An arrangement for spacing a floating body from a mother vessel during borehole-seismic measurements, wherein the floating body includes at least two buoyant bodies connected by a rigid framework and which supports the seismic equipment, the floating body is maintained in a correct position for transmitting seismic pulses by a crane or boom mounted on the mother vessel, a tube or hose system is mounted on the framework for ejecting a pressurized medium, preferably water, against the side of the vessel through nozzles, and the pressurized medium is transferred to the system through a hose coupled to a source of pressurized fluid on board the vessel.

Abstract: The invention is a deployment system for a marine seismic source array. A plurality of sources are suspended at different depths from a float. The system is adapted for deploying the float and the sources into the water and retrieving them for reloading onto the vessel. When the float is positioned on the water surface the sources sink to preselected water depths. The sources are retracted to the underside of the float in the retrieval process.

Abstract: Disclosed is a cable leveling device for a seismic marine cable. The cable leveling device features a motor which controls diving planes by way of direct mechanical linkage. The motor is controlled by a stored program digital processor connected in a closed loop feedback circuit. Optical reflective sensors are employed in the feedback loop to monitor the position of the mechanical linkage to directly determine the angle of the diving planes. A telemetry unit is provided to telemeter data from the cable leveling device to shipboard via the marine cable.

Abstract: An assembly for use in seismic surveys of the sea bed is towed behind a vessel and comprises groups of seismic signal transmitters which are towed through the water, being suspended from float buoys which are combined to form one body which may be formed as a sleeve having limited flexibility. The body is formed with a head member shaped for reducing resistance to the water, and connected to a coupling point for a tow wire to the vessel, which point lies forward of the head member and at the same depth as the transmitters.

Abstract: A device for use in borehole-seismic measurements at sea whereby seismic energy sources (7) are suspended below the surface (D) and connected to a handling line (2) which is operated by a crane arrangement on a vessel. By suspension of a minimum of two seismic energy sources (7) from a stand (3) at a distance from mutually separated floats (1) rotatably connected on horizontal axes (9) to the stand, seismic energy sources (7) can be placed and maintained at a constant depth below the surface, whereby several seismic sources (7) can be used simultaneously. The stand (3) is equipped in its central area with a guide (4) for the handling line (2), which is divided at the end connected to the respective energy sources' (7) suspension lines (8), which simplifies the positioning of the device.

Abstract: A method and apparatus for use in marine seismic data gathering comprises a vessel (1) is equipped for deploying and retrieving trailer cables and tows a plurality of cables (3) which are provided with at least one array of transmitters (5), which array constitutes a point source for a transmitter, and an acoustic cable, over the region to be investigated. The transmitter cables (3) are caused to become distributed laterally in relation to the tow direction, the distance between them, the firing power and firing timing being controlled from the vessel in accordance with data collected previously regarding the nature of the sea bed. The point source-formed transmitter arrays can be distributed both laterally and longitudinally in relation to the tow direction. The transmitter cables (3) are distributed laterally with the aid of otterboards (8).

Abstract: A marine seismic survey is disclosed in which a plurality of steerage centers are selected for circular traversal thereabout by a marine vessel towing a streamer cable. While the vessel and the streamer are following a circular track about a steerage center, the feathering of the cable creates a separate concentric track line for each of the mid-points between the receivers included in the cable and the source. In this manner an areal coverage is assured which requires no reliance on unpredictable and uncontrollable currents for the desired feathering. An additional important feature of the current disclosure is that there is little wasted time in which the survey vessel moves outside of the overall surveyed area. A preferred course tracking for the vessel is to move from the arc of one steerage course line to another in tangential fashion.

Abstract: A seismic data acquisition system for use in shallow water covered areas comprises a flotation device which serves also to house the electronic components; anchoring device with mechanical filter device to protect the anchor, so as to insure its maintaining its position; seismic sensor device for detecting seismic waves in the water and converting them to electrical signals; radio receiver device for receiving operational control instructions; and device for amplifying, digitizing and storing the electrical signals provided by the sensor, preferably on a removable tape recording device.

Abstract: High resolution, high penetration marine seismic stratigraphic system wherein a slanted cable comprising spaced-apart hydrophone arrays gather seismic reflections so that the corresponding primary and ghost reflections from a common interface gradually are spaced apart. The primary reflections are time aligned and stacked. The ghost reflections are phase reversed, time shifted and time aligned to coincide with the time aligned primary stack and then stacked to give a combined primary and ghost stack, which effectively includes almost twice the information as from the primary stack alone. No inverse notch filters are needed to correct for the ghost phenomenon. Focused noise out of the vertical plane is also virtually eliminated.