RU2663308C2 - Method for carrying out underwater/under-ice seismic profiling using a bottom seismic inspection streamer moved by an underwater vessel cross and the technological complex for its implementation - Google Patents

Abstract

FIELD: geophysics.SUBSTANCE: invention relates to marine geophysics and can be used in the search for minerals on the sea shelf, including in the shelf regions under ice. System of underwater/under-ice seismic profiling of the seabed is proposed, including a surface support vessel equipped with navigation, communication, control and power supply for working with underwater objects, lowered to the bottom of the support vessel, a carrier, in which a remote-controlled submarine vessel with an acoustic radiator is located, a buoyancy control device for the bottom streamer and a winch with a bottom streamer and a floating trunk cable placed on it. Seismic profiling is carried out by dragging a bottom streamer over the bottom of the submarine, giving it neutral buoyancy and laying the streamer on the bottom and irradiating it, giving the streamer a negative buoyancy.EFFECT: increase of economy, improvement of quality of received seismoacoustic material.5 cl, 5 dwg

Description

The invention relates to marine geophysics and can be used for geological exploration using bottom seismic streamers in marine waters under ice.

A device for providing seismic profiling of a deep sea shelf by laying seismic streamers on the seabed using an underwater carrier and a method of installing this device on the seabed (patent RU 2460096). The device consists of several parts that carry winches with seismic streamers installed on them. Delivery and installation of the device at the operating point, combining the device parts into a single system and laying the seismic beam to the bottom is carried out by a self-propelled multifunctional underwater station using uninhabited underwater vehicles located at this station.

The disadvantage of this method and device is the complexity of the entire range of tools used, as well as the need for operations on long profiles of multiple repetition of a multifunctional underwater station and uninhabited underwater vehicles for assembly and disassembly of the device, laying and folding of seismicos, the length of which is limited by the size of the winch drums installed on the device and in most cases it can be significantly less than the length of the studied profiles, which makes this method extremely expensive tnym.

A known method of conducting underwater-under-ice geophysical exploration and technological complex for its implementation (patent RU 2388022). This method is the closest to the claimed method in technical essence. In this method, seismic antenna spit tows are towed under the ice with the help of an underwater vessel that moves lag at the optimal geophysical depth and pulls the antenna spit along with winches that are discharged from the side winches located along the length of the submarine. The submarine contains ship propulsors with controlled thrust vectors, providing movement and dynamic positioning of the submarine, and operates under ice with a surface icebreaking support vessel - carrier of transport and rescue underwater vehicles, autonomous uninhabited underwater vehicles, bottom and towed acoustic beacons.

This method allows for continuous seismic profiling due to the towing of streamers by an underwater vessel, however, it does not provide laying of seismic surveying antenna streamers on the bottom to obtain higher quality seismic measurements. In addition, the implementation of a submarine, which is an analogue of a nuclear submarine and moving lag, requires a radical alteration of the basic solutions of submarines, which reduces the efficiency of the method.

The problem to which the present invention is directed is the development of a more cost-effective and more technologically advanced method for conducting underwater under-ice seismic profiling of the seabed with the help of seismic antenna streamers moved by an underwater vessel, providing a higher quality of the obtained seismic material.

To solve this problem, in contrast to the known method of conducting underwater-under-ice geophysical exploration using towing seismic surveys under ice using an underwater vessel containing a seismic acoustic emitter, ship propulsors with adjustable thrust vectors providing horizontal and vertical movement and spatial dynamic positioning of the submarine working together with a surface icebreaking support vessel, bottom and towed beacons (patent RU 2388022), new in the developed method is that the underwater vessel tows the bottom seismic survey, alternately changing the buoyancy of the streamer from negative to zero or close to zero buoyancy and vice versa, when the streamer is negatively buoyant, the streamer is laid to the bottom of the underwater vessel and the bottom is irradiated relative to the streamer, and when making the spit zero or close to zero buoyancy, the underwater vessel moves the spit along the profile.

To implement the developed method, a system of underwater under-ice seismic profiling of the seabed is proposed, in which:

- the surface icebreaking support vessel is equipped with navigation, communication, control and power supply facilities for working with underwater objects, lowered from the vessel to the bottom on a power cable-cable with a carrier-deepener, which includes an underwater vessel made in the form of an uninhabited remote-controlled underwater vehicle, device buoyancy regulation and a winch with a bottom oblique variable buoyancy placed on it and a floating main cable;

- the buoyancy control device includes a durable tank divided by a partition into two airtight compartments, a bellows is installed in the first compartment filled with low-density liquid filler, the base of which is attached to the front wall of the compartment and has a pipe in this wall to fill the bellows with water from the external environment , and the opposite side of the bellows can move inside the compartment, in the second compartment there is a pump system including a hydraulic pump, pipelines, a controlled valve and a control unit Nia, the controllable valve passes the liquid vehicle from the first compartment on one of the lines only through the hydraulic pump and further into the cavity of the bottom sleeve braids, and on another conduit passes back the filler only from the bottom braid directly to the first compartment;

- the bottom braid is made in the form of a flexible elastic polymer sleeve, at the ends of which there are hermetic connectors, while the braid is connected through the first hermetic connector to the buoyancy control device, and through the tail hermetic connector is connected to the main cable having neutral buoyancy, the root end of which is fixed to the winch installed in burrowing carrier, a cable embedded in the hermetic seals is passed through the sleeve to compensate for the longitudinal extension of the sleeve, on the cable between the geophones secured to the at a certain distance from each other, buoyancy garlands made of low density spheroplastic are placed, in which there are through channels through which the transit wires of electric communication lines pass, and channels for moving the liquid filler in the cavity of the bottom braid in the forward or reverse direction when its buoyancy changes ;

- a submarine containing a seismic acoustic emitter, ship propulsors with adjustable thrust vectors, providing horizontal and vertical movement and spatial dynamic positioning of the submarine, is equipped with a docking unit for fixing the buoyancy control unit on the hull surface and connected to the buoyancy control unit with a telecontrol and power cable placed on a winch mounted on the body of the buoyancy control unit.

The possibility of implementing the developed method is illustrated by drawings.

In FIG. 1 shows a technological complex of underwater-under-ice seismic profiling in the descent-lifting mode of a carrier-deepener from a surface support vessel.

In FIG. 2 shows a schematic layout diagram of a device for controlling buoyancy of a bottom braid.

In FIG. 3 presents a schematic layout diagram of a bottom spit of variable buoyancy.

In FIG. 4 depicts a technological complex in towing mode by an underwater vehicle of a bottom spit of variable buoyancy above the bottom surface.

In FIG. 5 shows the technological complex in the mode of irradiation by an underwater vehicle of a section of a profile after laying a spit of variable buoyancy to the bottom.

The technological complex (Fig. 1) includes a surface icebreaking support vessel 1, containing navigation, communication, control and power supply 2 for working with underwater objects, lowered to the bottom of the support vessel via a power cable 3 heavy carrier-deepener 4, in which the submarine 5 is placed, made in the form of an uninhabited remote-controlled underwater vehicle, a buoyancy control device 6, and a winch 7 with a bottom braid 8 and a floating main cable 9 placed on it.

The buoyancy control device 6 (FIG. 2) includes a robust reservoir divided by a partition 10 into two airtight compartments. In the first compartment filled with low-density liquid filler 11, a bellows 12 is installed, the base of which is attached to the front wall of the compartment and has a nozzle 13 for filling the bellows with water from the external environment, and the opposite side of the bellows can move inside the compartment. In the second compartment, a pumping system is installed, which includes a hydraulic pump 14, pipelines 15.16 and 17, a controlled valve 18 and a control unit 19.

A controllable valve 18 passes liquid filler 11 from the first compartment only through pipe 15 through a hydraulic pump and then through pipe 17 into the cavity of the bottom braid sleeve, and through pipes 17 and 16 it passes filler 11 only from bottom braid 8 back directly to the first compartment.

Variable buoyancy bottom braid 8 is made in the form of a flexible flexible polymer sleeve 20 (Fig. 3), the ends of which are equipped with pressure connectors 21 and 22. The bottom cable is connected to the buoyancy control device 6 through the pressure connector 21, and is connected to the main cable 9 through the pressure connector 22. A cable 23 is inserted through the sleeve 20 and sealed in the hermetic connectors 21 and 22 to compensate for the longitudinal elongation of the sleeve; on the cable 23 between the geophones 24 there are buoyancy lights 25 made of spheroplastic, in which there are through channels 26 through which tested wire electrical communications lines and through which can flow the liquid vehicle 11. Buoyancy 25 support cylindrical bottom braid on its entire length and, in addition, serve to compensate for excessive weighting streamer caused placement therein having high weight geophones and connecting wires. The external dimensions of the buoyancy 25 and the geophones 24 are chosen such that between their surfaces and the inner walls of the spit sleeve there is a gap for the passage of the filler 11.

The submarine 5 (Fig. 5) is equipped with an acoustic emitter 27, ship propulsors with adjustable thrust vectors providing horizontal and vertical movement and spatial dynamic positioning of the submarine (not shown in the drawings), docking unit 28 for fixing the buoyancy control unit on the surface of the hull and connected to the buoyancy control unit 6 by a telecontrol and power supply cable 29 located on a winch 30 mounted on the body of the buoyancy control unit.

The method of conducting underwater-ice seismic profiling of the seabed using a bottom seismicosa moved by an underwater vessel is implemented as follows.

A surface icebreaking support vessel 1 equipped with navigation, communication, control and power supply 2 for working with underwater objects enters the geophysical exploration area equipped with bottom acoustic beacons. Before starting work, the support vessel 1 determines its initial position in the research area and its coordinates relative to the known coordinates of the bottom acoustic beacons. From the support vessel 1, a heavy carrier-deepener 4 is lowered to the bottom along the power cable 3, in which there is an underwater vessel 5, a buoyancy control device 6, a winch 7 with a bottom braid 8 and a floating main cable 9. All located in the carrier-deepener 4 the devices have communication, control and power lines with a support vessel 1.

After submission of a motion command from the vessel, the submarine 5 with buoyancy control device 6 coupled to it leaves on the main propellers from the carrier-deepener 4 and pulls the bottom braid 8 attached to the buoyancy control device 8. In the process of exiting the bottom-braid carrier-deepener having negative buoyancy in the initial state, they give buoyancy close to neutral, for which purpose the control unit 19 of the buoyancy control device 6 sends a command to turn on the hydraulic pump 14 and eklyuchenie regulation valve 18 for download via conduits 15 and 17 under pressure in the sleeve cavity 20 of the liquid filler braids 11 of buoyancy control device 6.

The liquid filler entering the cavity of the braid sleeve from the buoyancy control device under a pressure exceeding the pressure from the external environment expands the walls of the elastic braid sleeve and increases its volume, thereby increasing the buoyancy of the braid to a value that allows it to not touch when leaving the carrier-deepener with a seabed ..

After the spit comes out completely from the carrier-deepener 4, the submarine 5 is directed, orienting its spatial position when moving along the bottom acoustic beacons, to the initial section of the studied profile, where they give the command to lay the spit to the bottom. Upon receipt of this command, the control unit 19 of the buoyancy control device 6 switches the controlled valve 18 to dump the volume of liquid filler 11 pumped from the buoyancy control device from the buoyancy control device, which returns through pipelines 17 and 16 to buoyancy control module compartment. In this case, there is a decrease in the buoyancy of the spit up to its initial negative, at which it can stably lie at the bottom. At the same time, the submarine 5, controlled by the operator from the surface support vessel 1, turns off the propulsion devices holding it above the bottom surface and also sinks to the bottom together with the buoyancy control device attached to it 6. Then, on commands from the support vessel 1, the docking unit 28 is activated the vessel is undocked from the buoyancy control device, rises above the bottom surface and, unwinding the telecontrol cable 29 from the winch 30, starts moving and irradiating the bottom with a seismic acoustic emitter 27 Signals reflected from the geological layers of the bottom are received by seismic receivers of the bottom of the streamer and through cable lines enter the supply vessel for accumulation and subsequent analysis.

Having finished irradiation of the section of the profile relative to the spit laid on the bottom, the submarine returns to the beginning of the spit and docked with the buoyancy control device. Having received a command from the support vessel to continue moving and move to the next section of the profile, the buoyancy control device increases the buoyancy of the spit, while the submarine, together with the control device, raises the spit above the bottom surface and starts towing the spit to the next section of the profile, where the operations of laying spit, irradiation of the bottom and the subsequent rise and movement of the spit. Given the lengths of the main cable 9 and the bottom braid 8, the maximum number of sections that can be processed in this way on one profile is equal to the quotient of dividing the length of the main cable by the length of the bottom braid.

Having finished processing the entire profile, the submarine is returned to the depth carrier 4 by winding the main cable 22 with the bottom braid onto the winch 7, while the submarine is held above the bottom surface due to its propulsors, and the bottom braid due to giving it neutral buoyancy.

After completing work on one profile, work on other profiles can begin from the standpoint of the carrier-deepener, or the carrier-deepener together with an underwater vessel and a bottom scythe can be lifted aboard the support vessel and moved to another research area.

The technological complex for conducting underwater-ice seismic profiling of the seabed using a bottom seismic streamer moved by an underwater vessel is formed mainly from known elements, for example:

- the surface support vessel is a classic icebreaker, equipped with a hangar for storing an underwater deepener carrier with an underwater vehicle and a seismic skid, an appropriate launching device and a set of navigation aids, cable communication lines, control and power supply for underwater vehicles, reception and storage geophysical information;

- the carrier-deepener in the design is an analogue of the “deep sea diving devices” (UGP) widely used in underwater operations, which are garages lowered from the surface of the surface vessel to the bottom for placement of autonomous or remote-controlled underwater vehicles in them [3];

- the submarine includes the basic basic solutions for relatively small uninhabited remote-controlled underwater vehicles with propulsion engines with thrust vectors controlled in the range of 0-360 ° and propulsion devices for moving in the vertical plane, supplemented by solutions for placing seismic acoustic emitters on them, such as, for example, a source of coherent broadband low-frequency acoustic radiation [4];

- the bottom seismic acoustic streamer includes well-known technical solutions in the field of seismic field acquisition and recording by linear seismic surveys with digital multicomponent seismic sensors, supplemented by fundamentally new original solutions that allow you to change the buoyancy of the streamer and move it with a relatively low-powered underwater vehicle by towing.

The feasibility of the proposed method of seismic profiling and the technological complex for its implementation is not in doubt.

The technical result is an increase in economic efficiency, manufacturability and quality of the material obtained is ensured by the following factors:

- in comparison with the known analogues that use autonomous multifunctional submarine stations in the form of specialized submarines as submarine carrier seismicos, the use of relatively small uninhabited telecontrolled underwater vehicles of the middle class is sufficient for the cost of 2-3 orders of magnitude;

- the transfer in the proposed technological complex to a surface vessel of providing functions for controlling and powering the underwater equipment, as well as placement of a bulky and heavy winch with a long oblique and long trunk cable on an underwater carrier-deepener, significantly relieves the underwater remote control apparatus from additional equipment, reduces the requirements for traction efforts of its movers, simplifies its design and, accordingly, the cost;

- the ability to change the buoyancy of the bottom braid allows seismic surveys of long profiles of a relatively short bottom braid in several stages by laying it on the bottom and towing without repeatedly repeating the operations of bleeding the braid from the winch and rewinding the bottom braid on the winch, which increases the manufacturability, reliability and safety of the method;

- seismic scythes lying at the bottom compared to seismic streamers towed in the aquatic environment have a higher noise immunity, in addition, it is possible to place vector seismic receivers in them that provide reception and registration of a multicomponent wave field, which improves the quality of the obtained seismic-acoustic material.

Information sources

1. Patent of Russia No. 2460096.

2. Patent of Russia No. 2388022.

3. Voitov VV Telecontrolled uninhabited underwater vehicles. Publishing house "Morkniga", 2012. Pages. 55-60.

4. Lebedev A.V., Malekhanov A.I. Coherent seismoacoustics. Izv. Universities. Radiophysics. 2003. 46 ı7 Pages 579-597.

Claims (5)

1. A method of conducting underwater-ice seismic profiling of the seabed during geophysical exploration of minerals using towing seismic surveys under ice using an underwater vessel containing a seismic acoustic emitter, ship propulsors with adjustable thrust vectors, providing horizontal and vertical movement and spatial dynamic positioning of the underwater vessel working together with a surface icebreaking support vessel, bottom and towed beacons, featuring the fact that the underwater vessel is towing the bottom seismic survey line, alternately changing the streamer’s buoyancy from negative to zero or close to zero buoyancy and vice versa, when the streamer is negatively buoyant, the streamer is laid on the bottom and the bottom is irradiated relative to the streamer, while giving the streamer zero or close to zero buoyancy, the braids move along the profile. 2. The underwater-under-ice seismic profiling system for implementing the method according to claim 1, including a submarine towing a seismic survey streamer containing a seismic acoustic emitter, ship propulsion with adjustable thrust vectors, providing horizontal and vertical movement and spatial dynamic positioning of the submarine, working together with the surface icebreaking support vessel, bottom and towed beacons, characterized in that the surface icebreaking support vessel is equipped with a medium navigation, communication, control and power supply for working with underwater objects, lowered from the vessel to the bottom on a power cable with a carrier-deepener, which includes an underwater vessel made in the form of an uninhabited remote-controlled underwater vehicle, a buoyancy control device and a winch with placed it has a bottom oblique variable buoyancy and a floating trunk cable. 3. The underwater-under-ice seismic profiling system according to claim 2, characterized in that the buoyancy control device includes a robust reservoir divided by a partition into two sealed compartments, a bellows is installed in the first compartment filled with low-density liquid filler, the base of which is attached to the front the wall of the compartment and has a pipe in this wall to fill the bellows with water from the external environment, and the opposite side of the bellows can move inside the compartment, in the second compartment there is a pumping system including a hydraulic pump, pipelines, a controllable valve and a control unit, while a controllable valve passes liquid filler from the first compartment through one of the pipelines only through the hydraulic pump and further into the cavity of the sleeve of the bottom braid, and through the other pipe it passes this filler only back from the bottom braids directly into the first compartment. 4. The underwater-under-ice seismic profiling system according to claim 2, characterized in that the bottom braid is made in the form of a flexible elastic polymer sleeve, at the ends of which there are pressure connectors, while the cable is connected to the buoyancy control device through the first pressure connector and connected to the tail seal A trunk cable with neutral buoyancy, the root end of which is fixed to a winch installed in a carrier-burrower, a cable terminated in hermetic sockets is passed through the sleeve to compensate for the longitudinal stretching the sleeve, on the cable between the geophones, fixed at a certain distance from each other, buoyancy buoys made of low-density spheroplastic are placed, in which there are through channels through which transit wires of electric communication lines pass and channels for moving the liquid filler in the cavity bottom braid in the forward or reverse direction when changing its buoyancy. 5. The underwater-under-ice seismic profiling system according to claim 2 or 3, characterized in that the underwater vessel is equipped with a docking unit for fastening on the surface of the hull of the buoyancy control unit and is connected to the buoyancy control unit by a telecontrol and power cable placed on the winch mounted on the body of the unit buoyancy regulation.

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