RU2110816C1 - Method protecting geophysical equipment against environment - Google Patents

Abstract

FIELD: solving search tasks of seismic prospecting, earthquake prediction, study of seismotectonic processes. SUBSTANCE: special feature of method consists in filling of free internal spaces of equipment and frame of geophysical station with inert fluid and jelly-like medium. Bottom leads-out of cables ensure serviceability of geophysical equipment in corrosive media under external pressure above 1000.0 atm. EFFECT: expanded application field of method. 1 cl, 5 dwg

Description

 The invention relates to experimental and applied seismology, more specifically to methods and techniques for recording seismic signals and wave fields, and can be used to solve search problems of seismic exploration (primarily for gas and oil), earthquake prediction and the study of seismotectonic processes of the planet.

 Lime is a way to protect seismographs from external influences by isolating the device with a special container (box), the walls of which kept the "microclimate" within certain limits (according to variations in pressure, humidity, air flow) and thereby ensured normal operation [1]. The development of marine seismology required a qualitative improvement of this method. A known method of protecting seismic equipment from the penetration of sea water and significant hydrostatic pressure by placing seismometers and a useful signal recording unit in an airtight thick-walled metal case, lowered to the seabed on a steel cable. The body is cylindrical in shape and is designed for immersion depth pressure (2000 m). According to this scheme, a modern generation of bottom seismic stations is created [2]. However, according to the description, the development of depths of about 10,000 m (external pressure 1000 atm) requires the development of new design principles.

 Closest to the claimed is a method of protecting downhole geophysical equipment, placed in a waterproof cylindrical case, when part of the equipment - piezoceramic transducers - each of which is a monolithic block, is placed in transformer oil [3]. The disadvantage of this method is that the main problems of other methods [1-2] are not resolved: geophones and auxiliary equipment are placed in a heavy sealed enclosure inside which the equipment operates at normal pressure in the air; the inputs (ports) of the signal and power cables must ensure tightness at the differential pressure: hydrostatic column - normal internal pressure in the chamber. These features do not allow ensuring the operability of the equipment at pressures of the order of 20,000 atm existing in the deep bottom parts of the mud volcano.

 The invention is aimed at increasing the depth of immersion in the geophysical environment of the vents of a mud volcano using modified standard geophysical equipment.

 The result is achieved by the fact that upon reaching the indicated depths, the protection of geophysical equipment from the surrounding geophysical medium is carried out by filling a weakly compressible, non-viscous chemically passive liquid with the internal free space of the body of each geophysical instrument, wiring the cable through the bottom hydraulically permeable part of the body, and separating the internal volume of the body from the permeable part of the elastic soft shell, equipment rooms in the upper part of the internal volume of the station building, filling its the vigorous internal space of the station building with a jelly-like passive medium; winding the cable-rope onto the station body in the form of a sphere rolling the latter down the inner slope of the vent portion of the volcano.

 Distinctive features of the proposed method are the location of geophysical equipment in the upper part of the volume of the body of the geophysical station, filling the internal volume and cavities of the body of the equipment with an inviscid inert liquid, filling the internal volume of the body of the geophysical station with a jelly-like inert mass, the hydraulic permeability of the bottom parts of the body of the equipment and station, the separation of the contact surfaces of the liquid body of the equipment - jelly-like mass, jelly-like mass - outboard geophysical medium with elastic impermeable sheaths, cable network outlet through the bottom of the hulls, ball winding of the cable-rope to the station body and the descent of the station to the studied horizons of the earth's crust at the initial stage by rolling the winding-station system along the inner slope of the volcano vent.

 Filling free volumes and voids in the bodies of geophysical equipment with an inert inviscid liquid, in the internal volume of the geophysical station with a jelly-like inert mass, and the permeability of the bottom parts of the bodies and chambers eliminate the problem of destruction of the equipment and the station with external excess pressure when the station is immersed in the mud volcano vent to deep faults (10 km, pressure 20,000 atm), since one-way pressure is replaced by comprehensive compression in an inert environment, and similar performance and at the same time will allow the use of thin-walled structures of light alloys. The separation of the contact surfaces is an inviscid liquid - a jelly-like substance - a geophysical medium, the cable network through the bottom of the structure, the location of the geophysical equipment in the upper part of the station volume guarantee isolation of outboard fluid from contact and mixing of the liquid, which eliminates the failure of the equipment due to chemical aggressiveness fluid and its conductive properties ensures long-term operability of the station at design depths. The inertness of an inviscid high-pressure fluid under high pressure, the stability of its physicochemical properties, insignificantly or within design limits change the main operating characteristics of standard geophysical equipment, therefore the use of the latter (geophones, tiltmeters, seismic vibrators, etc.) will simplify and reduce the cost of conducting measurements.

 Winding onto the station body of the cable network in the form of a spherical shell and dumping this system into the mud volcano vent during its activity along the inner slope will allow more efficiently overcoming protrusions and terraces along the dive route to the estimated depth. At the same time, a thick layer of coiled cable softens the impact of stones carried by the fluid flow from the deep areas of the volcano, and also protects against contacts with the hostile aggressive inclusions of SJ, mitigates temperature loads during passage of fluid ignition zones during the active phase of volcanism. The listed design features of the entire system, due to the proposed method, reduce the weight and the total cost of the experiment so much that, given the need to have constant observation points, there is no need for many auxiliary equipment (for example, a lift).

 In FIG. 1 shows the General layout of the deep geophysical station (GTS) that implements the proposed method; in FIG. 2 - an example of a modification of a standard seismic receiver; in FIG. 3 is a diagram of a station with spherical winding of a cable network; in FIG. 4 - type GTS for spherical winding; in FIG. 5 is a diagram of the applications of GHS for the study of a mud volcano.

 In FIG. 1 indicates the body of the deep geophysical station (GHS); 2 - internal cable network; 3 - block geophysical equipment; 4 - external housing section of the common cable network, stretched from the docking pad through the bottom of the housing 1; 5 - thin-walled housing; 6 - gel-like aggregate of the internal volume of the GHS; 7 - bottom element of the permeable part of the hull; 8-elastic shell; 9-sided laying of the carrier cable; 10 - fluid intake device: 11 - lower heat flow sensor; 12 - telluric current sensor; 13 - anchor; 14 - 16 - elements of the stabilizer-hopper of the cable rope: 17 - spatially stabilized table for precision geophysical equipment; 18 - acoustic transmitter of geophysical information; 19 - acoustic information relay; 20 - airborne fluid analyzer; 21 - plot cable cable in working condition. In FIG. 2 marked: 22 - cover of the seismic receiver type SM-Z; 23 - inviscid chemically passive liquid; 24 - mechanical elements of the geophone; 25 - permeable element of the lower part of the body of the geophone; 26 - elastic shell. In FIG. 3: 27-spherical winding of the entire cable of the estimated depth of immersion; 28 - GHS building; 29 - an additional membrane. In FIG. 4:30 - spring clips. In FIG. 5:31 - vent of the crater of a mud volcano; 32 - griffin; 33 - day surface; 34 - flow of deep fluids; 35 - intermediate chamber or knee; 36 - GGS of a cylindrical type at a design depth; 37 - immersion of the GHS with spherical winding of the cable; 38 - mobile geophysical laboratory; 39 - the surface of the seismic antenna; 40 - the deep part of the seismic antenna; 41 - intermediate block thermocouple-electrode.

 Protection of geophysical equipment in accordance with the proposed method is carried out in the following way.

 According to the research objectives and the object of study determine the type of GHS (Fig. 1, 3 - 5). A complex of ground equipment (Fig. 5) and an industrial model of standard geophysical equipment (Fig. 2). Then, through the permeable element 25, the free internal volume of the apparatus is filled with an inviscid, poorly compressible fluid 23 (for example, ethyl alcohol, gasoline, silicone fluid, distilled water) and is sealed with a sheath 26 (Fig. 2). The cable network of each device is connected to a docking pad mounted on the inner surface of the GHS housing. Then the geophysical equipment is fixed in the upper part of the internal volume of the GHS (Figs. 1, 3, 4), and the common cable network is led out through the bottom of the station building to the bunker of the cable cable 14-16, after which this object is filled through the permeable lower part of the body, channels and openings 7,10 with a jelly-like passive substance 6 (for example, solid oil, a viscous version of silicone fluid), in some cases installing an intermediate shell 29, and is sealed from the external environment with an elastic shell 8. Material for elastic impermeable shells varieties of chemically resistant rubber, teflon, etc. are used. The equipment protected in this way is used for observations by placing the GHS in the vent or griffin of an active or being in the stage of activation of a mud volcano (Fig. 5). Under the influence of its own weight, the GHS 36 falls down (the density of the medium is 1.5 - 2.5 g / cm, the average density of the GHS is 4 - 6 g / cm) through the sedimentary cover to the crystalline basement to the sources of deep fluids at a depth of 8 - 12 km (Fig. . 5).

 When lowering the cable, the cable 9, 21 is wound from the bobbin of the stabilizer-hopper 14 - 16 (Fig. 1), and then from the coil of the geophysical laboratory 38 and provides energy-information connection with the laboratory. Regardless of the depth of immersion, the equipment is protected from high pressure and aggressive environmental influences. External pressure through the hydraulically permeable bottom elements of the GHS bodies (Figs. 1, 3, 4) is transmitted through impermeable flexible shells to a gel-like filler, which transfers the same pressure through the permeable bottom parts of geophysical instruments and flexible shells to an inviscid filling fluid of the internal volume of the instruments. As a result, hydrostatic equilibrium with the intake medium is established and maintained in all volumes and elements of the equipment and the GHS, and the comprehensive high pressure of a neutral inviscid liquid does not impede the normal functioning of geophysical equipment (for example, seismic). Even the overboard pressure of 2000 atm causes a 15 - 25% compression of the volume of aggregate fluids, which allows the entry of the external environment only in front of the first elastic shell and does not affect the performance of the GHS. In the process of diving through a volcanic vent, the GHS provides information on temperatures, heat fluxes, fluid composition, seismic and electromagnetic fields along the movement path (Fig. 5). Upon reaching the crystal structures, the GHS is used as a stationary complex deep observatory to solve many applied and fundamental geophysical problems. In the case of a deformed vent and griffin and / or volcanic plug in the upper part of the channel (Fig. 5), a GTS variant with a spherical winding of a cable cable is used at the moment of volcano activation (Fig. 3, 4), since rolling the GTS along inclined slopes is more effective than lowering with an anchor. In this case, the winding 27 protects the equipment from shocks and thermal pulses. Upon reaching / the estimated depth with a fully unrolled cable, the GTS, under the action of the massive element 1 (Fig. 4) or anchor 13 (Fig. 1), occupies the working position.

 All the above examples indicate the feasibility of the proposed method of protecting geophysical equipment from the environment and at the same time allow conducting qualitatively new research with mud volcanoes. The simplest GTS prototype was created using modified standard equipment (seismic receivers SV-20: SV-5), tests confirmed its operability.

 To implement the proposed method and create devices for its implementation, an extensive infrastructure has been practically created from geological and geophysical maps of regions with active mud volcanoes to the numerous elements and systems necessary to create hydraulic structures. The proposed method has no alternative, it will allow creating a GHS network, conducting fundamental and applied experiments, for example, in hydrocarbon prospecting, seismicity prediction, deep seismic emission fields, geochemical analysis of juvenile fluids, etc.

Claims (2)

 1. A method of protecting geophysical equipment from the environment by placing the equipment in a strong sealed enclosure of the geophysical station and sealing the inputs and outputs of the information and power cable network, characterized in that the internal free space of the body of each geophysical instrument is filled with a weakly compressible inviscid chemically passive filler fluid, carried out cable through the bottom of the device, which is hydraulically permeable from the outside, and the internal volume of the device is separated from the the desired part with a soft elastic shell, after which the devices are placed in the upper part of the internal volume of the body of the geophysical station, the common power and communication cable is brought out through the lower part of the external wall of the body of the geophysical station and it is passed along the external surface of the body of the geophysical station to the docking unit on the mounting bracket of the station to transport cable, fill the free internal space of the body of the geophysical station with a jelly-like passive medium, and in the lower part of the body of the geophysical station with the morning side cover its hydraulically permeable part with elastic shells.  2. The method according to claim 1, characterized in that the cable is wound on the body of the geophysical station in ball form.

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