Abstract: Embodiments herein use an acquisition vessel towing a plurality of receivers and a seismic source and a source vessel towing a seismic source to acquire seismic data corresponding to a subsurface below a bottom surface of a body of water. When activating the seismic source on the acquisition vessel, the plurality of receivers acquire survey data for a central coverage area underneath a swath defined by the plurality of receivers. However, when activating the seismic source on the source vessel, the plurality of receivers acquires survey data for a side coverage area. The embodiments herein control a separation distance between the acquisition and source vessels so that there is a gap between the central and side coverage areas resulting from activating the seismic sources towed by those vessels. This gap can reduce the cost and time required to perform the seismic survey.

Abstract: An arrangement for monitoring a submarine reservoir includes a number of sensor units located in an array on the seabed, and an interrogator unit for obtaining data on the reservoir from the sensor units. The interrogator unit includes a transmitter unit for sending optical signals to the sensor array and a receiver unit for receiving modulated optical signals from the array. Optical radiation from an optical source is transmitted along an uplink optical fiber which is split in a number of positions to form the array. The receiver unit includes optical-to-electrical converters for converting the optical signals to electrical signals, a phase demodulator, a multiplexer, a signal processor, and recording unit. The interrogator unit is divided into a concentrator and an interrogator hub, where signals are transmitted between the interrogator hub and concentrator along a riser cable. This enables the interrogator to be moved between a platform and the seabed.

Abstract: There is described an optical seismic cable (2) comprising a number of sensor units (5) spaced along the length of the cable and a number of connection units (4) spaced along the length of the cable, the cable further comprising a number of first optical fibers extending substantially continuously along the cable from one connection unit to the next, and a number of second optical fibers which each extend part-way along the cable between adjacent connection units, and wherein at each connection unit at least one first optical fiber is joined to a second optical fiber, and wherein at the sensor units sensors are joined to said second optical fibers.

Abstract: There is described an apparatus and method for deploying a sensor array comprising a plurality of sensors (5) joined together by connection cables (6) in one or more “chains”, and connected to an input/output device (8). An input/output connection unit (7, 15) is provided on a carrier (10), and the sensors are held on or in deployment devices (14a-14e) mounted to the carrier with their connection cables (6) connected to the input/output connection unit (7, 15). The input/output device (8) may also be mounted to the carrier, and connected to the connection unit (7, 15). The carrier (10), sensors, and input/output device (8) may be delivered as a single package to the area where the sensor array is to be deployed. The sensors are then moved from the carrier to their final positions. The deployment devices (14a-14e) may be detached from the carrier and moved sequentially to the sensor positions, and a sensor may be removed from the deployment device at each sensor position.

Abstract: A pressure apparatus including a first end cap, a second end cap, a hollow housing connected to the first and second end caps, a locking ring connected to the second end cap, a first termination connected to the first end cap, and a second termination connected to the second end cap.

Abstract: An armored cable termination/fiber-optic seal which connects a fiber optic cable—the fiber optic cable including one or more armor wires and one or more cable tubes—to a pressure housing, the armored cable termination/fiber-optic seal including: an armored termination which locks the one or more armor wires in a conical cavity; sealing paths which block water from traveling in the interstitial space between the one or more armor wires and the one or more cable tubes into the pressure housing; and fiber feed-through tubes which block water from traveling in the interior of the one or more cable tubes into the pressure housing.

Abstract: An arrangement for monitoring a submarine reservoir comprises a number of sensor units located in an array (1) on the seabed, and an interrogator unit for obtaining data on the reservoir from the sensor units. The interrogator unit comprises a transmitter unit (20) for sending optical signals to the sensor array and a receiver unit for receiving modulated optical signals from the array. Optical radiation from an optical source (22) is transmitted along an uplink optical fibre which is split in a number of positions 36, 38 to form the array. The receiver unit comprises optical-to-electrical converters (54) for converting the optical signals to electrical signals, a phase demodulator (58), a multiplexer (60) for multiplexing signals from the phase demodulator, a signal processor (68) and recording unit (70).

Abstract: The invention is a method for geological structure contour modeling and imaging beneficial for quality control and evaluating aerial extent parameter during seismic survey design, quality control of process of migration during processing stage of seismic data, and quality control of structure maps during interpretation of 3-D seismic volume. This method provides a quick and efficient parametric 3-D representation of geologic structures, also allows the use of existing depth data for structure contour modeling and imaging. Normal incident rays, either linear or curved, are traced starting from points along selected contours of structural surface and ending at imaged points on the recording surface to define projected location of the imaged structure contours at the recording surface. Further analysis and quality control is conducted by generating structure maps utilizing third party software using structure contour data, and data for the corresponding contours imaged on the recording surface.

Abstract: A sensor arrangement for monitoring a oil reservoir comprises a sensor array (1) comprising a plurality of sensor units (5) located over an area to be monitored; an interrogator unit (30) comprising a transmitter (402) for transmitting optical signals and receiver for obtaining data on the reservoir from the sensor units, a demodulator (418) for demodulating the received signals, and a recorder (420) for recording the demodulated signals. The arrangement includes an uplink optical cable (408) for transmitting the signals to the sensor array and a downlink optical cable (410) for transmitting signals from the array to the receiver. At least one of the optical cables has an optical amplifier (412, 414). The arrangement enables the interrogator to be remote from the array, for example 150 km or more, obviating the need for significant power to be supplied at the array.

Abstract: There is described a method and apparatus for deploying and covering undersea seismic sensing cables to improve seismic coupling between the sensors of the cable and the seabed. The method comprises simultaneously deploying a submarine seismic cable and a mat in order to cover at least the sensor units of the cable. The mat may be attached to the cable prior to laying the cable on the seabed, and is preferably simultaneously laid with the cable by unwinding the cable and mat from a drum. The mat may be continuous, or may be in discrete sections attached to the cable at spaced locations.

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: Air guns to be fired in water for carrying out seismic prospecting of the sea bed are suspended from a single rigid buoyant-body pararane so that the position of the air guns in the water is not unfavorably influenced by wave movements on the water surface.

Abstract: A float for use in seismic surveys of the sea bed supports a plurality of seismic pulse transmitters (6) which are suspended on lines (7) beneath the float (1). At a distance from the front end of the float (1), on one sidewall thereof, a fastening device for a towing cable and a lead-in for control lines and lines for supplying operating medium to the pulse transmitters are provided. These lines and cables are gathered in a common line (3) which extends behind the tow ship. The line (3), at a distance away from the float (1), is connected to a line (4) which leads to a length-regulating device (12) inside the front section of the float. The float is also provided with at least one motor (10) with a drive shaft (9)leading to hoisting drums (8) for the lines (7) to the respective seismic pulse transmitters (6). Both the motors (10, 12) and the seismic pulse transmitters (6) are connected to the pneumatic supply line.

Abstract: A method for the reduction of data logging in seismic data processing, in which data are transmitted between a plurality of data acquisition devices with a plurality of channels and a central receiving and recording device by using a plurality of transmission modules each of which is essentially allocated to a date acquisition device and each channel is assigned corresponding seismic traces comprises, providing real physical seismic traces and synthetic seismic traces, inserting the synthetic traces between the real traces, locating the seismic traces with relative uniform, physical distance, assigning corresponding simulated channels to the synthetic traces, assigning to each simulated channel an estimate of the real value for a corresponding physical channel, and adapting each estimated value to the values of at least one adjacent physical channel assigned the corresponding real physical traces.

Abstract: A device which can be used for digital signal processing, e.g. filtering of digital signals in the form of continuous bit streams that are linear digital representations of analogue signals. The device is composed by cascading individual filter sections. Each filter section comprises an integrating and multiplying unit, or units, an inverting unit or units and an adding unit or units.The device has been implemented on a monolithic integrated programmable circuit together with soft controlled solid state switches such that a preferred filter configuration may be selected by programming the circuit.

Abstract: A method for interactive contouring of seismic data for procuring seismic maps (60a, 60b, 60c) which provide a three-dimensional picture of the various structural layers (5a-5n, 12a-12n, respectively) within an area (11) which is circumscribed by intersecting shooting lines (6a-6d). In order to achieve a shorter processing time for procuring such maps, the data representing the individual structural layers (5a-5n) referred to a fixed reference line (2a) are procured as a color coded echo line (12h) on a graphic data screen (22), the indication of depth being given as a color value in relation to a preselected color scale (40). The interpreter can insert between the various points having the same color value on the echo line (12h) fresh interpreted values in the same grid according to the same color code, so that for each structural layer (5a-5n, 12a-12n, respectively) there can be provided a mapping (60a-60n) having surface adaptations given in various color values directly on the screen (22).

Abstract: A float for use in seismic surveys of the sea bed supports a plurality of seismic pulse transmitters (6) which are suspended on lines (7) beneath the float (1). At a distance from the front end of the float (1), on one sidewall thereof, a fastening device for a towing cable and a lead-in for control lines and lines for supplying operating medium to the pulse transmitters are provided. These lines and cables are gathered in a common line (3) which extends behind the tow ship. The line (3), at a distance away from the float (1), is connected to a line (4) which leads to a length-regulating device (12) inside the front section of the float. The float is also provided with at least one motor (10) with a drive shaft (9) leading to hoisting drums (8) for the lines (7) to the respective seismic pulse transmitters (6). Both the motors (10, 12) and the seismic pulse transmitters (6) are connected to the pneumatic supply line.

Abstract: A system and method for forming a model of an underground geological formation is disclosed wherein a quantity of non-solid material of the type which solidifies at volumetric positions impinged upon by preselected incident energy as used. Memory means are provided which have uniquely addressable location for storing data indicative of the desired and actual material states at respective volumetric positions. Means are additionally for scanning the data and sequentially directing the energy at supported, non-blocking, volumetric positions in the medium volume.

Abstract: A connector for fiber optic cables includes an elongated tubular housing and a pair of termination assemblies which surround the end of each fiber optic cable. A lens element is adjacent one end of each termination assembly, and a sleeve surrounds each lens element and a portion of the termination assembly, and a lip on the sleeve spaces and coaxially aligns the lens elements one from the other.

Abstract: A plurality of streamer-cable bulkheads mounted within a streamer cable in cascade for radially scattering tube-wave noise from a streamer-cable. Each bulkhead consists of an annular body with conical surfaces converging at a desired angle, extending outwards from both ends of the annular body. An axial hole and a plurality of off-axial holes extending through the bulkhead for receiving therethrough, electrical conductors and stress members respectively. Noise traveling within the tube in a waveguide mode, impinges upon the conical surfaces of the cascaded bulkheads, and is reflected out of the streamer-cable jacket.