Abstract: A communication housing for devices external to a solid marine seismic cable, especially for level control devices, comprises an upper housing half and a lower housing half, coupled together around the cable. The upper housing half includes a plurality of wells, for example three wells, each adapted to receive a communication coil. The lower housing half has no such wells. The communication coils are wound in series to reinforce the signal strength of the communication signal. The communication coils are preferably formed to two segments, joined together at a flexible joint to reduce the likelihood of breakage of the coil core as the cable is wound onto a takeup reel aboard the exploration vessel.

Abstract: A communication housing for devices external to a solid marine seismic cable, especially for level control devices, comprises an upper housing half and a lower housing half, coupled together around the cable. The upper housing half includes a plurality of wells, for example three wells, each adapted to receive a communication coil. The lower housing half has no such wells. The communication coils are wound in series to reinforce the signal strength of the communication signal. The communication coils are preferably formed to two segments, joined together at a flexible joint to reduce the likelihood of breakage of the coil core as the cable is wound onto a take up reel aboard the exploration vessel.

Abstract: A control device or “bird” for controlling the position of a marine seismic streamer is provided with an elongate, partly flexible body which is designed to be electrically and mechanically connected in series with a streamer. In its preferred form, the bird has two opposed wings which are independently controllable in order to control the streamer's lateral position as well as its depth.

Abstract: A neural network to predict seismic streamer shape during seismic operations having an input layer, an optional hidden layer, and an output layer, each layer having one or more nodes. The first layer comprises input nodes attached to seismic data acquisition operational parameters as follows: vessel coordinates, receiver coordinates, time, vessel velocity, current velocity, wind velocity, water temperature, salinity, tidal information, water depth, streamer density, and streamer dimensions. Each node in the input layer is connected to each node in the hidden layer and each node in the hidden layer is connected to each node in the output layer, the output layer outputting a predicted cable shape. The hidden layer may be omitted. When the hidden lay is omitted, each node in the input layer is attached to each node in the output layer. Each connection between nodes has an associated weight and a training process for determining the weights for each of the connections of the neural network.

Abstract: A marine seismic source for generating acoustic source energy. A housing has a continuous exterior perimeter which is moveable to displace water. Movement of the housing can be accomplished by providing alternating convex and concave exterior surfaces connected with inflection points. The composite shape provides movement inwardly or outwardly, and can be moved with different types of actuators. Piezoelectric elements can be activated to move the housing surfaces and to change the internal housing volume. The resulting pressure pulse provides acoustic source energy useful for the evaluation of subterranean geologic formations and for other purposes.

Abstract: A seismic ocean bottom positioning device include a series of seismic stations spaced apart at a predetermined interval along a cable. Each station includes a hydrophone, a motion sensing device such as a geophone and an acoustic positioning circuit. A preamplifier is coupled to a seismic channel. The hydrophone is also coupled to the seismic channel. An acoustic channel is also coupled to the preamplifier and coupled to the hydrophone.

Abstract: A system and method for synchronizing collection of seismic data used for seismic surveys. In one embodiment, positioning signals received from a positioning system, such as the Global Positioning System, are used to acquire a highly accurate time value. Data collection is then initiated at a prespecified time using the time determined from the positioning signal.

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 method for acquisition of seismic data from an area surveyed using a group of seismic energy sources and a group of seismic streamer cables, particularly a marine area, includes forming a first group A from at least two elements of either seismic energy sources S or seismic streamer cables C having a spacing X between said elements, forming a second group B from at least two of the other elements of sources S or cables C than that forming group (A), spacing the elements in group B a distance equal to X multiplied by the number of elements in group A, forming a group C from at least two subgroups each consisting of a group A, spacing said subgroups in group C in distance equal to the distance between two elements in group B multiplied by the number of elements in group B, the spacing between two adjacent subgroups being equal to the lateral distance between midpoints between the subgroups, and forming further groups as desired D, E, F etc.

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; andb.

Abstract: A high-order, polynomial regression curve is fitted to a global set of first-arrival pick times as a function of the nominal ranges between a plurality of acoustic sources having known geodetic coordinates and a plurality of acoustic detectors whose coordinates are imperfectly known. The polynomial is applied to the pick times to provide pick time distances with the vertical velocity gradient removed. The known source coordinates, the nominal detector coordinates and the pick time distances are combined to provide a quadratic surface to provide a common data block containing the coefficients for modeling the lateral velocity gradient. Using the so-determined coefficients, the imperfectly-known detector positions are iteratively updated using the Helmert blocking technique.

Abstract: A high-order polynomial regression curve is fitted to a global set of first arrival times as a function of the nominal ranges between a plurality of acoustic sources having known geodetic coordinates and a plurality of acoustic detectors whose coordinates are imperfectly known. The order of the polynomial is chosen to be that order that minimizes the variance of the parameters about the regression curve. The polynomial is used as a quasi-velocity function for iteratively optimizing the best estimate of the ranges between each detector and every source station. The best estimate of the detector position is derived by multi-lateration using the computed ranges.

Abstract: A method for determining the position of seismic equipment wherein acoustic transmitters transmit spread spectrum sequences which are received by the seismic sensors in the equipment whose position has to be determined. By collecting and processing the signals thus produced, it is possible to determine the position of seismic equipment with reference to each individual sensor in the seismic equipment each time a measurement is take. The already existing conventional seismic sensors which are provided in a streamer are used to record the transmitted spread spectrum signals. By calculating time differences between the sensors' reception of a spread spectrum signal it is possible to calculate the position of the seismic equipment.

Abstract: This invention relates generally to a method and system for synchronizing the timing of events between and among vessels using a common timing reference.

Abstract: One or more slave acoustic transponders are secured to selected parts of a seismic bottom cable whose location is imperfectly known. A master transponder broadcasts an interrogation pulse from each of a number of different, known locations distributed along a line of survey. In response to an interrogation pulse, a slave transponder emits an encoded signal that is received by the master transponder. The acoustic flight time between each pulse broadcast and encoded-signal reception constitutes a range measurement to the participating slave transponder. Resolving a gather of several range measurement from different known broadcast locations, focussed on an identifiable transponder, defines the transponder location.

Abstract: The present invention provides a method for on-line real-time processing of processing navigational data for determining the location of sensor and receiver points in a navigational network having a number of different types of devices. Observations from these devices are obtained using a coordinate system that follows appropriate nominal sailing lines. Outlying observations are discarded using w-statistics for the observations. Any correlated observations such as compass azimuths are uncorrelated. The uncorrelated observations are then sequentially processed in an extended sequential Kalman filter, which provides the best estimate of the station coordinates. These estimated coordinates are then used to determine the location of the source and receiver points.

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 magnetic heading sensor alignment and roll reducing device is provided. A enerally cylindrical assembly has a first end and a second end. Each end has a plurality of grooves located equiangularly on a circle with the center thereof located at the cylindrical assembly's center longitudinal axis. Bearings, positioned at and supported by the first and second ends, support a magnetic heading sensor at either end thereof. The bearings provide the sensor with rotational freedom about the center longitudinal axis. A counterweight is affixed to the sensor such that its center of gravity and the sensor's center of gravity are located at a common axial loci. A plurality of longitudinal spring strips are provided to fit into corresponding ones of the grooves on the first and second ends of the cylindrical assembly. The spring strips cooperate with the inner surface of a tubular housing when the device is inserted therein. All materials used to construct the device are non-magnetic.

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: A terrestrial surveying system comprising an electro-optic total station (1) for combined measurement of angle and distance and a connection to data storage (11) or data processing devices (20), the total station (1) and at least one portable position-measuring unit, which is separated spatially from the total station and equipped with a receiver (3) for a satellite position-measuring system, are connected to one another through a wireless data transfer device (12, 13). The data processing device is preferably set up for determining coordinates, for coordinate transformation from the satellite position-measuring system to the terrestrial coordinate system of the total station and for consistency checking of the data determined.

Abstract: A marine seismic system includes a streamer cable which is towed by a vessel in a body of water. The streamer cable includes a plurality of hydrophones located at predetermined positions in the streamer cable which receives vibrations resulting from a seismic event occurring in the water, and provides signals corresponding to the received vibrations. The streamer cable also includes a plurality of receivers located at predetermined position in the streamer cable. Each receiver receives acoustical signals provided by acoustical sources and provide electrical signals corresponding to the received acoustical signals. A seismic event source provides a seismic event in the water. A plurality of acoustical sources cooperating with the seismic event source also provides encoded acoustical signals into the water when the seismic event source provides a seismic event.

Abstract: A method is disclosed for determining the separation between a seismic energy source and a seismic sensor, the location of which is known imperfectly. After the source emits a wavefield, the first-arriving impulse at the sensor is statistically processed to form a range statistic that is related to the true travel time between the source and the sensor. A set of range statistics from a plurality of source positions are filtered and converted to range loci, the intersection of which marks the location of the sensor.

Abstract: A laser beam is projected from either an underwater body or an overhead support platform, with the laser energy being detected by the other piece of apparatus using a photo detector. Either the projecting or the receiving optics is servo driven to maximize the light energy received by the photo detector. The relative position of the underwater body with respect to the support platform, typically a tracking aircraft, is determined by measuring the position of a driven element laser or photo detector, in either one or two planes, i.e., two or three dimensions, to provide a measure of the trailing distance and when desirable, the lateral offset distance.

Abstract: Apparatus and method for transmitting and receiving hydroacoustic pulses used to determine the spatial separations between pairs of such apparatus. According to a preferred embodiment, the apparatus transmits hydroacoustic pulses having a selected shape and frequency at specific times and also determines the time of arrival of received hydroacoustic pulses having a known shape and carrier frequency. Included is a transducer for converting the hydroacoustic energy received from a body of water into electrical energy and for converting electric pulses into hydroacoustic pulses which are then coupled into the body of water. Electric pulses having a selected shape and carrier frequency are digitally synthesized in response to a count comparator.

Abstract: A method for determining the position of at least two seismic streamers (S.sub.1, S.sub.2) in a reflection seismic measuring system, wherein hydroacoustic distance measurements are used which are taken by means of acoustic transceivers provided in vessels (1), buoys (8), floats (5), seismic sources (2) and in the seismic streamers (S.sub.1, S.sub.2). Absolute reference positions are determined by position determining equipment provided in at least two locations, for instance, on a vessel (1) or a float (5). The acoustic transceivers and the position determining equipment form a three-dimensional structure. The position determination takes place by trilateration between the acoustic transceivers and the determination of at least two reference positions so that there is no dependency on compass bearings or optical visibility, and high redundancy is obtained. The method is particularly suited for application in connection with three-dimensional marine seismic surveys.

Abstract: A method is disclosed where acoustic pulses are used to calculate the velocity of the medium. The inventive aspect of the invention is that the acoustic velocity may be calculated without initially knowing the separation distance between the source and the distant receivers. The method utilizes established geometrical relationships which may be solved to produce the velocity. The velocity is often used to calculate the separation distances between the desired points.

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: The application discloses a method of determining the relative positions of a plurality of points located substantially in a common plane at or close to the surface of the sea, which method comprises deploying at each of said points an acoustic element comprising an acoustic transmitter and/or an acoustic receiver; sequentially actuating at predetermined time intervals at least a predetermined number of the acoustic transmitters and observing the responses of at least a predetermined number of the acoustic receivers in response thereto, such that all of the acoustic elements are operated at least once, whether in the transmit or receive mode or in both said modes; and subjecting the observed responses to signal processing to derive the spacing between each receiving element and each transmitting element, and hence to derive the relative positions of said points.

Abstract: A method for determining the position of a marine seismic receiver cable of the type which is towed behind a seismic survey vessel through the sea, wherein the azimuth and the distance from the vessel to points along the seismic receiver cable are measured, and the coodinates of these points are calculated on the basis of these values. A hydroacoustic measurement method is utilized, based on a super-short baseline system integrated with a gyrocompass, for measuring the azimuth and distances in accordance with signals from transponders, beacons, responders and/or similar instruments installed on or within the seismic receiver cable.

Abstract: Method for determining the geometry of a seismic wave emission device comprising a plurality of seismic sources (S11, S12, S21, etc.) towed by a ship (1) with different transverse and longitudinal offsets. It comprises the isolated triggering of each of the sources (S11, S12, S21, etc.), the detection of acoustic waves coming therefrom by means of proximity sensors (C) arranged at known distances from other sources and optionally from the ship or from a seismic flute, and the recording of detecting signals by means of an acquisition system on board the ship (1). After various corrections of the distances and various processings performed on the signals, parameters (propagation time, phase shiftings) representative of intersource distances are determined and, consequently, the relative coordinates of the sources with respect to each other and their positions with respect to other points. The previous measurements are completed by other measurements related to the immersion depth of different sources.

Abstract: In a method of locating and orienting a first direction linked to the position and to the orientation of an autonomous first mobile object (M), such as a ship towing a marine geophysical prospecting cable, and a second direction formed by a non-autonomous second mobile object (Bj), such as a buoy at the trailing end of the towed cable, and at least one reference point on the first mobile object relative to a fixed reference radionavigation system comprising at least two reference beacons (Si, Si+1) the first mobile object (M) and the second mobile object (Bj) are respectively provided with a first communication device (MI) providing communications between the first mobile object (M) and the reference beacons (Si, Si+1) and a second communication device (MJ) providing communications between the first mobile object (M) and the second mobile object (Bj). They are further provided with a communication device (BIJ) providing communications between each reference beacon (Si, Si+1) and the second mobile object (Bj).

Abstract: A method and device are provided for determining by acoustic telemetering the position of immersed objects with respect to a ship having a location assembly connected thereto including two acoustic transmission-reception assemblies and a towed locating base including two other assemblies offset laterally with respect to the path of the ship, in which method two measuring cycles are carried out successively, the first one consisting in determining by acoustic telemetering the position of the mobile locating base with respect to the locating base fixed to the ship, while the second consists, still using acoustic telemetering, in determining the position of the towed objects with respect to the mobile locating base. Then the coordinates of all the towed objects are determined with respect to the ship.

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 sensor for resolving the left-right ambiguity encountered in horizontal line hydrophone arrays consists of an orthogonal pair of dipole hydrophones, a monopole hydrophone, and a tilt sensor, the tilt sensor connecting the dipole hydrophones so as to provide a single dipole hydrophone which is always oriented horizontally. The tilt sensor consists of two variable capacitors made from hollow cylinders of high permittivity dielectric material, partially filled with a quantity of liquid mercury which forms the variable inner electrodes of the capacitors. The outer electrodes of the capacitors, on the outside of the cylinders, having a sinusoidally-shaped perimeter and being oriented at right angles to each other, are connected to the crossed dipoles in order to provide the required horizontal dipole hydrophone.

Abstract: A marine cable for detecting converted shear waves reflected from the strata beneath a body of water in response to a compressional wave generated in the body of water. The cable comprises a jacket, a mount attached to the stress member, a geophone positioned in the mount, a first weight assembly attached to the stress member and positioned proximate a first end of the mount and a second weight assembly positioned proximate a second end of the mount. The mount is sized and made of a material so that its weight is sufficient to cause at least the portion of the cable jacket that is adjacent the mount to contact the seafloor. The first and second weight assemblies are sized and made of material so that their respective weights cause at least the portion of the cable jacket that is adjacent to the respective weight assemblies to contact the seafloor.

Abstract: An electronic circuit is used for processing data to locate an on-bottom seismic cable wherein the first energy arrivals of seismic acoustic pulses are detected by hydrophones with an on-bottom cable and time intervals to timebreak to arrival are measured, stored and used to determine the hydrophone position and, thus, the location of the on-bottom cable.

Abstract: The positions of seismic subarrays are determined using special hydrophones in a streamer cable which listen for acoustic signals generated from each seismic subarray.

Abstract: A combined heading and depth sensor for acquisition of both compass heading and depth data and transmission of the combined data over a two wire communication link as a single packet of information to a remote data acquisition unit. The sensor includes a remote reading compass assembly, a depth sensor and circuitry to interface the compass and depth sensors to the communication link. A communication protocol is defined permitting addressable interrogation of a plurality of combined heading and depth sensors over the two wire link.

Abstract: A method is disclosed for locating the position of a marine streamer using two boats and a series of transponders in the streamer. A first pulse is electrically triggered and then generated by the transponders and by a transceiver mounted in the seismic vessel that tows the streamer. These first pulses are detected at a slave ship and the respective distances to the acoustic sources are calculated. The actual locations of the streamer transponders are calculated by trilateration when a second pulse from transponders 2-5 is detected at the slave ship. This second pulse is an acoustically triggered product of an electrically triggered initial pulse generated by a first transponder. This acoustically triggered pulse is used to determine the distance from the seismic ship to the transponder nearest the seismic ship and then to successively further transponders down the streamer length. Thereafter the positions of the transponders may be calculated.

Abstract: The present invention relates to a ground position controller utilizing a microcomputer system interconnected to a digital field system (DFS) via a system bus, for generating, formatting and displaying information (for insuring integrity of field operations) under a variety of shooting and collecting conditions.

Abstract: A method for determining the absolute geophysical location of a streamer using reference signal source(s), or alternately detector(s), of unknown location. The absolute geophysical location of a seismic streamer is determined by the optimal sequential use of the field measurements of reference signal travel time, streamer magnetic heading and conventional navigational measurement. The absolute location determination is accomplished in three steps. Each step solves for one aspect of streamer location by optimally utilizing one of three types of field measurement. This procedure requires no a priori knowledge of the absolute location of the reference signal source(s), or alternately detector(s).

Abstract: A device for determining the position in the water of an elongate element (a seismic streamer for example) towed while submerged, by means of measuring elements such as compasses and pressure gauges spaced apart along said elongate element. Said compasses and pressure gauges are disposed inside profiled bodies firmly secured to sleeves fixed about said elongate element and transmit the measurements, by means of a hertzian wave transmission assembly, to a sensor inside the elongate element, which is connected by a transmission cable to a reception assembly connected to a central unit installed in the towing ship.

Abstract: A method for locating an ocean bottom seismic cable is disclosed wherein a series of shots from a seismic pulse generator are fired. The distance to one seismic pulse detector is determined for each shot defining a spherical surface upon which the detector may be located. The intersection of the spherical surfaces determine the exact location of the detector. Depth detectors may be used to eliminate one half of the possible locations for each shot.

Abstract: Method and means are provided for determining the position of a submerged marine streamer towed behind an exploration vessel. An array of sets of at least three transponders secured to the ocean floor generate distinguishable acoustic pulses upon a command signal. These signals are received by receivers housed in the streamer. The position to each receiver may be triangulated from the data generated.

Abstract: Sensors mounted in detachable modules are located at selected positions along a cable, such as one used in marine seismic exploration, adapted to be towed behind a vessel in a body of water. The sensors are selectively addressable, either individually or as a group, by coded signals sent through the cable. When addressed, the sensors provide readings of the earth's magnetic field vector. The readings are used to provide an indication of the position of the sensors and thus the cable relative to the towing vessel. Cable depth readings may also be made by the sensors.

Abstract: A system for sorting data from seismic surveys at sea. The data are acquired by signal transmission/receiving by streamer cables, which streamers are equipped with position-defining instruments. For the sorting, the area to be surveyed is subdivided into squares of defined size and position. The data provided through the measurements is sorted, and accepted data is processed further and transferred to the individual squares in the grid pattern. On the basis of the data, the configuration and position of the streamer is also computed, and information regarding this is displayed on a screen. On the basis of these results, the coverage of the measurement area may be determined, and an adjustment of the vessel's steering can be carried out to allow one to obtain the best coverage of the area. The acquired data is stored for later treatment.

Abstract: The position of a submerged object towed at great depth from a ship is determined, with respect to the ship, from measured values of the travel time of acoustic pulses between the ship and the object. These pulses are emitted at different locations of the ship and received at a point of the object. The values of the travel times of the pulses are measured and digitized on the object and transmitted by cable to the ship where they are processed, in combination with values representing the distances between the emission locations, to determine the coordinates of the object with respect to a system of axes associated with the ship.

Abstract: Method and apparatus are provided for locating a towed float relative to the towing vessel. The method determines the range from at least two known spaced apart locations on the towing vessel to the float and determines the position of the float from the intersection of the at least two ranges. The apparatus includes a microwave transceiver selectably interconnectable with a plurality of microwave antennas at known spaced apart locations on a towing vessel, a microwave transponder on each float whose locations is to be determined, and suitable controller and/or computer means to calculate ranges and intersections of ranges.

Abstract: A geophone assembly for use in a marine seismic cable to detect converted shear waves reflected from the strata in response to a compressional wave generated in the body of water associated with the strata. The geophone assembly comprises a cylindrical mount that has a central aperture and a geophone positioned in the central aperture. The mount has a plurality of additional apertures that are sized and positioned to accommodate the plurality of stress members in the cable, and the mount is sized and made of a material so that the weight of the mount is sufficient to cause at least the portion of the cable jacket that is adjacent the mount to contact the seafloor.

Abstract: Apparatus and method are provided for locating seismic sources suspended below a float, seismic streamer cables and other towed seismic apparatus relative to a towing vessel. The range and bearing from a selectively energizable acoustic source on or near the float, cable or apparatus to the towing vessel is measured by an acoustic phased array.