RU2381530C1 - Seafloor standalone station for geophysical and geological exploration operations - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to standalone seafloor seismic stations and can be used in different geophysical and geological exploration operations, particularly for monitoring the seismic environment. The station consists of a flow-type sealed container which is a compact metal cylinder. The top part of the container is closed by a flat cap-flange with a pressure ring and is tightened by bolts and nuts. Inside the container there are accumulators, sensors for measuring the seismic field and electronic apparatus. On the outer surface of the container there is a hydroacoustic antenna, sensors for measuring the hydroacoustic field, apparatus for station searching during emersion, and a device for immersion and emersion. The electronic apparatus consists of a unit for picking up, processing and storing signals from sensors for measuring seismic and hydroacoustic fields, and the an electronic unit for controlling the acoustic antenna, circuit breaker, radio beacon and flashing light-emitting diode beacon. Apparatus for station searching during emersion is a radio beacon and a flashing light-emitting diode beacon. The device for immersion and emersion consists of a circuit breaker, anchor-ballast, fastening and launching straps and floats. In a set with the inner equipment, the container has negative buoyancy.

EFFECT: increased reliability, reduced weight and size of the structure.

2 cl, 1 dwg

Description

The invention relates to offshore autonomous bottom stations and can be used to perform various geophysical and geological exploration works, including for monitoring the seismic situation.

Currently, the following areas of creation of autonomous bottom stations can be distinguished, which differ in the types of pop-up carriers of geophysical equipment and the anchor-ballast-buoyancy systems used.

1. Float-free single-unit ballast-buoyancy systems are the most common and widely used at the moment in the world. The necessary positive buoyancy is created by a solid spherical body - an instrument container, inside of which are located seismic sensors, signal recording equipment, storage devices, converters and power sources (for example, bottom stations of Geomar Germany - www.geomar.de, Ifremer France - www .ifremer.fr, JAMSTEC Japan - www.jamstec.go.jp, ADSS Russia - www.edboe.ru). The main positive feature of such non-floating single-block systems is the simplification of the design of the plant as a whole, which leads to an increase in its reliability and simplification of the technology of work. The main disadvantages: the relatively small value of the positive buoyancy of the system does not allow for a high ascent rate, the geophones have insufficiently tight contact with the seabed, which is necessary for optimal operation and maximum signal-to-noise ratio, and it is impossible to minimize the size of the robust instrument container housing, as this leads to loss of positive buoyancy.

2. Floatless multi-unit ballast-buoyancy systems. The necessary positive buoyancy is created by the instrument container (for example, bottom stations of Oceanographic Institution USA - www.obsip.org, University of Carrack Great Britain - www.carrak.co.uk). The main characteristic feature of such non-fusible multi-unit ballast-buoyancy systems is the possibility of spatial separation of all geophysical equipment in spaced strong housings, in particular, the separation of geophysical sensors from recording equipment, which allows a denser contact of the sensors with the bottom. But the implementation of a multi-unit system leads to a significant complication of the design, an increase in overall dimensions and cost of production. In addition, in the case of placing a container with sensors directly to the bottom, it is possible to create emergencies caused by suction of the container with seismic sensors and muddy viscous bottom sediments. This leads either to the need for an even greater increase in the positive buoyancy of the instrument container for tearing off the block of seismic sensors, or to the creation of a special mechanism for discarding the sensor block.

3. Float ballast-buoyancy systems. The necessary positive buoyancy is created by an additional float module (for example, bottom stations of the firms “LDEO” USA, “SIO” USA - www.obsip.org). Float systems can increase positive buoyancy after separation of the anchor, which without much difficulty solves the problems of separation of the silted block of seismic sensors or increase the speed of ascent. But existing models have a significantly complicated design, increased weight and size characteristics, are difficult to maintain and expensive to manufacture.

Considering all the pros and cons of the above stations, the autonomous bottom seismic station ("ADSS" LARGE "), described in patent RU 2229146 C1, 05.20.2004, was taken as a prototype. Autonomous bottom seismic station (ADSS) according to the patent of the Russian Federation No. 2229146 contains installed on the bottom of a deep-sea self-floating carrier of geophysical equipment (NGA). NGA consists of two hemispheres, between which a sealing ring is laid. Moreover, the NGA includes a registration unit, an orientation determining unit, a synchronization unit, a hydroacoustic beacon control unit, a disconnector control device and a power supply unit, as well as a hydrophone, an hydroacoustic beacon antenna mounted on the outside of the sealed container, and a device for placing and removing the NGA from the bottom soil, made in the form of an anchor-load - a concrete disk or a rectangular parallelepiped with a flat base and with a hemispherical recess for placement of an NGA container with fastening e th through breakers. In addition, there are tools for searching for a pop-up NGA made in the form of a flashing beacon and / or an active radar reflector. A positioning unit is located inside the sealed container, and an antenna of the NAVSTAR and / or GLONASS satellite radio navigation system is installed outside. The registration unit includes a three-component seismic receiver module of three geophones or accelerometers for measuring the wave field and a storage of measurement information.

The main disadvantages of ADSS are the result of the design of its robust hull - NGA, which should have positive buoyancy. This, first of all, worsens the physical contact of the NGA with the anchor weight and, accordingly, reduces the sensitivity of the seismic sensors and degrades the quality of the received data. The requirement for positive buoyancy reduces the ability to minimize the size of the NGA, which automatically reduces the lifting force of the hull in the water. And the greater the vertical length of the station, the stronger the effect of bottom currents on it - the lower the overall noise immunity. In addition, the lighter and more stable the design of the robust building and the entire station in running order, the easier and more convenient it is for service personnel to work, the higher the efficiency of the work.

The objective of the proposed technical solution is to create a reliable station with high operational characteristics (with high sensitivity to useful signals and good noise immunity), convenient to maintain, providing good contact of the seismic sensors with the seabed, small in weight and size, and inexpensive to manufacture.

The problem is solved as follows. Offshore autonomous bottom station is proposed for geophysical and exploration work, which includes a compact sealed hollow metal body of cylindrical shape. Inside the housing are batteries, seismic field sensors and electronic equipment, including an electronic unit for recording, processing and storing signals from sensors for measuring seismic and hydroacoustic fields and an electronic control unit for an acoustic antenna, a disconnector, a beacon and a flashing LED beacon. On the outer surface of the sealed enclosure, a sonar antenna, hydroacoustic field measurement sensors, an immersion and ascent sensor system disconnector, after-ascent station search tools, including a radio beacon and a flashing LED beacon, and a station immersion and ascent device are installed.

A distinctive feature of the proposed station is that the sturdy case is made of metal (for example, steel, aluminum or titanium) of the appropriate thickness, withstanding the necessary hydrostatic pressure, and is a cylinder whose axis is vertically in the working position of the station (see drawing). In the lower part, it is closed with a flat flange cover made of the same material with an o-ring and tightened with fastening screws and nuts. The design is proposed, first of all, based on the requirement to improve the transfer characteristics of elastic vibrations in the contact area of the station with the seabed. To do this, it is necessary to ensure the negative buoyancy of a strong body with internal equipment, and its average density to be brought to a value of at least 1500 kg / m ³ , which allows optimizing the internal layout (in a cylindrical body, such optimization is easier than in a spherical one), minimizing weight and size parameters and leaves a wide selection of metals for the manufacturer.

An important distinguishing feature is the design of the device for providing immersion and ascent of the station, made in the form of a ballast anchor, mounted on the body by means of a disconnector, trigger and securing lines, and buoyancy. Buoyancy is a hollow cylinder (or torus) with a height of at least half the height of the cylinder of a solid body, solid or assembled from the corresponding hollow flat disks made of composite material based on modern syntactics that can withstand high pressures up to 1000 atmospheres and with a density of less than 700 kg / m ³ , in the internal space of which is placed a solid hull of the bottom station, fastened to buoyancy by fastening slings in the upper part of the station. Trigger slings securing buoyancy with a breaker in the lower part of the station are pulled through special ears-fasteners on the anchor-load, which further increases the station's downforce to the seabed. This arrangement and layout maximizes the contact between the seismic sensors located in a sturdy hull and the seabed, the overall streamlined design, minimizes the vertical length of the station and, accordingly, reduces the influence of possible bottom currents.

The analysis of the prior art carried out by the applicant has established that there are no analogs characterized by sets of features identical to all the features of the claimed device, autonomous bottom station, therefore, the claimed invention meets the condition of "novelty."

Currently, the authors are not aware of autonomous bottom stations having a similar hull structure and anchor-ballast-buoyancy systems, convenient, reliable and easy to operate, maintain and transport, providing maximum contact between the seismic sensors and the seabed, with the smallest possible vertical length, which minimizes noise the effect of bottom currents on the quality of registration of useful signals.

Search results for known technical solutions in this and related fields of technology in order to identify features that match the distinctive features of the claimed invention from the prototypes showed that they do not follow explicitly from the prior art.

The invention is illustrated in the drawing, which shows a diagram of the bottom station in vertical section. The following notation is introduced:

1 - strong case;

2 - flange cover;

3 - sonar antenna;

4 - seismic field measurement sensors;

5 - electronic unit for recording, processing and storage of signals from sensors for measuring seismic and hydroacoustic fields;

6 - electronic control unit for an acoustic antenna, a disconnector, a beacon and a flashing LED beacon;

7 - anchor cargo;

8 - trigger slings;

9 - batteries;

10 - means of station search after ascent, including a beacon and a flashing LED beacon;

11 - mounting slings;

12 - hydroacoustic field measurement sensors;

13 - breaker;

14 - special anchor ears;

15 - buoyancy.

The device operates as follows.

The marine autonomous bottom station for geophysical and geological exploration is delivered to the place of setting on the appropriate vessel, equipped with charged batteries 9, tested, programmed to work in the required mode, closed by a flange-cover 2. Immediately before diving, the sturdy case 1 is attached to the anchor-load 7 trigger slings 8, extending through special mounting-ears 14 on the anchor weight 7 and fastening on the one hand to the fastenings of the trigger slings on the disconnector 13, on the other - to the pl avuusti 15. At the point of setting the station sinks to the bottom, providing the maximum possible contact with the seabed due to its design. In accordance with the internal work schedule, the collection of information begins with seismic field measurement sensors 4 and hydroacoustic field measurement sensors 12, processing of this information and its storage in the electronic unit for recording, processing and storage of signals 5. After completion of the planned work, the internal timer or The electronic control unit for the acoustic antenna, disconnector, radio beacon and flashing LED beacon 6 gives the command from the onboard sonar antenna an ascent command. The disconnector 13 drops the trigger lines 8 and frees the station from the anchor-cargo 7, the buoyancy 15 together with the strong body 1 rises to the surface. After the discovery of an autonomous bottom station, using the sonar channel or search tools of station 10, the station is lifted aboard.

An additional technical result consists in the simplicity of the design, consisting of independent units, the small size and weight of the station and resistance to rolling, which greatly facilitates the work of maintenance personnel and transportation conditions and reduces the cost of production.

Thus, the above information proves that when implementing the claimed invention, the following conditions were met:

- a tool embodying the device of the invention in its implementation, is intended for use to perform various geophysical and exploration works, including for monitoring the seismic situation;

- for the claimed invention in the form described in the independent claim, the possibility of its implementation using the described or other means known prior to the filing date of the application has been confirmed;

- a tool embodying the claimed invention in its implementation, is able to provide the specified technical result.

Therefore, the claimed invention meets the condition of patentability "industrial applicability".

Claims (2)

1. Offshore autonomous bottom station for geophysical and geological exploration, including a sealed robust housing with batteries located inside, seismic field sensors and electronic equipment, including an electronic unit for recording, processing and storing signals from seismic and hydroacoustic field sensors, and an electronic unit control the acoustic antenna, circuit breaker, beacon and flashing LED beacon, on the outer surface of the durable housing installed They include a hydroacoustic antenna, sensors for measuring the hydroacoustic field, means for finding a station at ascent, including a radio beacon and a flashing LED beacon, and a device for providing immersion and ascent, including a breaker, ballast anchor, fastening and launching slings, and buoyancy, characterized in that it is durable the casing is a compact sealed metal hollow cylinder, the axis of which is located vertically in the working position of the station, in the lower part the casing is closed with a flat flange cover made of The same material with a sealing ring and is tightened with fixing screws and nuts, complete with internal equipment, has negative buoyancy. 2. Marine autonomous bottom station according to claim 1, characterized in that the design of the device for providing immersion and ascent of the station is made in the form of a ballast anchor, mounted on the hull by means of a disconnector, trigger lines, and buoyancy, which is a hollow cylinder or torus, one-piece or recruited from the corresponding hollow flat disks from an optimized composite material based on modern syntactics, into the internal space of which is placed a solid case of the bottom station, attached to the buoyancy of the cross yaschimi slings in the upper part of the station, and trigger lines securing the buoyancy with break at the bottom, are pulled through a special mounting-ears-anchored cargo.