RU2785252C1 - Mobile pulse source of elastic oscillations - Google Patents

Abstract

FIELD: geophysical equipment.

SUBSTANCE: invention relates to geophysical equipment and is intended for excitation of elastic longitudinal vibrations during seismic exploration. The field of application covers seismic studies of the upper part of the geological section, both in engineering and geological surveys, and in the search for mineral deposits. A mobile pulsed source of elastic vibrations is claimed, consisting of a massive cylindrical projectile, a cylindrical body equipped with a projectile retaining device and a conical stopper, a cylindrical cup with a replaceable impact platform and holes, a flange connection between the body and the cup, a combustion chamber, and an initialization device. A massive cylindrical projectile is an integral part of the combustion chamber, to which an initialization device is attached by a threaded connection, consisting of a striker with a groove and a thread for an eye nut, two springs, a striker retainer, a striker cover and an initialization cord. In this case, the cone stopper is attached to the cylindrical body with cone screws, and the projectile holding device consists of three ball clamps, the axes of which are located at an angle of 120° to each other in a plane perpendicular to the main axis of the cylindrical body. Wherein the ball clamps are held by the clamping springs located in the nuts rigidly fixed to the cylindrical body, and the clamping force of the springs is regulated by adjusting bolts interacting with their external threads with the internal threads of the nuts.

EFFECT: increase in the energy of a single impact on the ground and the ability to adjust the energy of a single impact; reduction of radial energy losses of impact on the ground and reduction of the intensity of surface waves-interference; expansion and adjustment of the spectrum of excited oscillations.

1 cl, 8 dwg

Description

The invention relates to geophysical equipment that provides the process of excitation of elastic vibrations during seismic exploration.

The scope of the developed source covers seismic studies of the upper part of the geological section, both in the search for mineral deposits and in engineering geological surveys.

Almost the entire range of seismic sources is represented on the Russian seismic equipment market [1], but most sources require additional equipment either for operation or for transportation.

In seismic exploration of shallow depths, two types of impulse sources are used - shock and explosive [2]. Impact sources include, for example: falling weight [3], spring [4], hydraulic (see Patent of the Russian Federation No. 2322685, class G01V 1/147, 2006 [5]), pneumatic (see Patent of the Russian Federation No. 2246740 , class G01V 1/147, 2002 [6]). The listed sources have the following common disadvantages: significant dimensions and weight, which leads to lack of mobility on difficultly rugged and wooded areas; high probability of a double (second) impact with a single impact, which reduces the quality of field records; require significant physical labor and/or special vehicles (specialized chassis) to move along the observation profile; require special additional energy sources (batteries, compressors, gasoline units); physical observation is worked out over a considerable period of time.

The greatest application in practice was found by such devices as portable small-sized pulsed source of seismic signals "KVANT" (electrodynamic principle of operation, force 30 kN) [7] and "Yenisei EM-1.6" (electromagnetic principle of operation, force 16 kN) [8]. However, these sources, despite their high power characteristics and small dimensions, are heavy and require additional devices, such as batteries for charging and recharging and specialized chassis for transportation during work. In addition, the electrical version of the operation of these devices implies high-quality insulation of the internal parts of the device from the penetration of dirt and moisture, which is not always possible in the field - a swamp, rain, snow, wells filled with water and liquid mud.

Explosive sources of oscillations in shallow and engineering seismic surveys are used extremely rarely. This is due to the danger of transporting explosives, the need for equipment and protection of explosives warehouses, the danger of explosions near the earth's surface, low efficiency and the impossibility of using them in urban industrial agglomerations.

Thus, the generalized terms of reference for modern developed sources are formulated as follows: high-resolution shallow mobile seismic survey with an environmentally friendly (non-explosive) source.

Currently, of the seismic sources on the market, there are only two mobile small-sized sources, the transportation and use of which can be carried out by one person over rough terrain - these are a seismic gun and a sledgehammer [9]. A seismic gun is the most successful known example of an impulse source of vibrations for the purposes of shallow seismic exploration. In a seismic gun, to generate elastic vibrations in the ground, the energy of the release of powder gases in a shallow well is used. It mainly uses a charge of black powder, which is loaded into standard 12-gauge hunting cartridge cases.

The disadvantage of these sources is the low intensity of exposure and, as a result, the shallow depth of research.

The closest in technical essence to the proposed invention is a pulsed powder source of elastic vibrations (see Patent for invention RU 2439620 C1, 01/10/2012. Application No. 2010124548/28 dated 06/15/2010. [10]), which is taken as a prototype.

The device consists of a chamber with a stop bracket on the lower end, a receiver, a percussion mechanism body with a metal button on the upper end, a rod with a rubber seal of a movable protective disk, a cross with handles and a safety device in the form of a fork.

The inner part of the chamber has a narrowing in the form of a ledge of a rectangular shape, and its muzzle is made in the form of a cone, expanding in the direction of the muzzle. This technical solution leads to the following result:

- firstly, the ledge provides during the shot the delay of the obturator wads with their subsequent destruction, while forcing pressure develops, which is necessary for the full and fastest combustion of the charge of smokeless hunting powder, which in turn allows you to maximize the energy of the generated pulse, reduce it duration and expand the spectrum of excited oscillations;

- secondly, the proposed shape of the outlet provides a uniform distribution of powder gases over the volume of the bottom of the well, which reduces the amount of irreversible plastic deformation of the soil, which reduces the resulting vibration excitation energy.

The cartridge chamber is connected to the receiver by a multi-threaded thread, which ensures high locking strength and the ability to quickly replace the spent cartridge case with a new loaded cartridge. The recharge time of the source is no more than 30 seconds.

Mechanical initialization (piercing) of the cartridge is carried out by striking with a light hammer on a metal button located on the upper end of the rod passing inside the rod.

The rubber seal located on the rod has a diameter comparable to the diameter of the well, thereby, when the device is installed in the working position, it tightly closes the wellhead and prevents the release of powder gases, which ensures a more complete transfer of shot energy into the ground, and, consequently, increases the depth of penetration of seismic signals.

The protective disk is made of plastic or hard rubber and moves freely along the shaft. During the excitation of vibrations, it additionally compacts the well and excludes the release of soil particles towards the operator, ensuring his safety.

The cross with two rubber handles provides comfortable and safe holding of the device during operation.

At the lower end of the chamber there is a stop bracket, which, in the event of an unauthorized charge of the propellant element into the cartridge, prevents its ejection from the barrel, ensures a constant distance between the muzzle of the chamber and the bottom of the well and prevents clogging of the muzzle with soil, thereby increasing the stability of the energy indicators of the impulse from shot to shot.

A safety device in the form of a fork (located in the upper end of the rod), which locks the rod of the percussion mechanism, ensures safe handling of the device during carrying and in preparation for the shot.

The device works as follows.

A well with a diameter of 6 cm (comparable to the diameter of the sealing ring) and a depth of 50-100 cm is drilled along the seismic profile at each picket (physical point) with a manual or portable motor-drill. The proposed vibration source is inserted into the well until it stops. At the command of the seismic station operator, the source operator, holding the crosspiece with his hand and the protective disc with his foot, strikes the metal button with a light hammer, after which the special blank cartridge is initialized. The gases released during the sharp combustion of smokeless powder hit the bottom of the well, thereby exciting elastic vibrations in the soil. These vibrations are recorded by seismic sensors placed along the profile. After working out the physical point, a transition is made to the next one, during which the source is recharged.

The operator unscrews the chamber, removes the spent cartridge case, inserts a new cartridge, screws the chamber, places the source in the well drilled in advance at the next picket.

For the operation of the device, specially equipped blank cartridges in a 12-gauge plastic sleeve with a charge of smokeless powder intended for use in hunting shotgun cartridges and plastic obturator wads that collapse during the shot are used.

The disadvantages of the prototype include the following:

- the impact on the soil is carried out due to the impulse imparted by the powder gases, which provides a small impact force (up to 4 kN ) and, as a result, a small depth of research;

- the presence of a distance between the muzzle and the bottom of the well reduces the energy transfer coefficient of the powder gases to the soil, and also leads to the fact that part of the energy of the powder gases is dissipated in the radial direction and creates intense surface interference waves, which also causes a decrease in the useful force of impact on the soil;

- in the process of testing the excitation point, direct close contact of the operator carrying out the testing of the excitation point with the device is required, which is unsafe and increases the risk of industrial injuries;

- the excitation initialization process is carried out using a hammer, which makes it difficult to simultaneously press the device to the ground or requires the participation of two operators in the process of working out the excitation point, one of which presses the device, and the other performs initialization with a hammer;

- fixed diameter of the muzzle eliminates the possibility of adjusting the dynamic range of the excited vibrations.

The technical result that can be obtained by implementing the proposed invention:

- increase in the energy of a single impact on the ground and the ability to adjust the energy of a single impact;

- reduction of radial losses of energy of impact on the ground and reduction of the intensity of surface waves-interference;

- expansion and adjustment of the spectrum of excited oscillations;

- increasing the safety of device operation and reducing the risk of industrial injuries due to the absence of the need for direct direct contact of the operator with the device in the process of working out the excitation point;

- ensuring long-term repeated use of the device, due to the execution of the technical elements of the device from structural steel, and the maintainability of all components and structural elements.

The technical result is achieved by the fact that the mobile pulse source of elastic oscillations consists of the following technical elements made of structural steel: a massive cylindrical projectile; a cylindrical body equipped with a projectile retaining device and a conical stopper, as well as a thread for fastening the combustion chamber; combustion chambers; initialization devices; cylindrical glass.

The design of a mobile pulse source of elastic oscillations is illustrated by figures, where:

- in Fig. 1 external view of a cylindrical body with a projectile retaining device and a cone stopper;

- in Fig. 2 combustion chamber with initialization device;

- in Fig. 3 housing of the initialization device in section;

- in Fig. 4 cylindrical body in section ( a ) with the layout of the device holding the projectile ( b );

- in Fig. 5 cone stopper ( a ) and a cylindrical body assembly with a projectile placed in it ( b );

- in Fig. 6 cylindrical glass with a shock platform in the section;

- in Fig. 7 massive cylindrical projectile;

- in Fig. 8 mobile pulse source of elastic oscillations in the section at the moment of working out the excitation point.

The cylindrical body 1 has a thread 2 for fastening the combustion chamber 3, a device holding the projectile in the form of ball retainers 4 and a conical stopper 5 (see Fig. 1).

The combustion chamber 3 has an internal thread 6 for fastening to the body 1 and an external thread 7 (see Fig. 2 and Fig. 4a ). The sleeve for the hunting cartridge 8 is inserted into the combustion chamber from the side of the thread 7. The body of the initialization device 9 is screwed onto the thread 7. The body of the initialization device 9 has an internal thread 10 for screwing onto thread 7 and a hole 11 through which the striker 12 passes during initialization and strikes in the primer of a hunting cartridge. To cock the striker 12, it has a thread for the eye nut 13 and a groove 14 for the striker retainer 15. The striker is located in the inner hole 16 in the cylinder of a smaller diameter of the body of the initialization device 9. In addition to the described elements, the initialization device also includes two springs 17 and 18 for holding the striker 12, cover 19 and cord 20 (see Fig. 2 and Fig. 3).

The projectile holding device consists of three ball clamps 4, the axes of which are located at an angle of 120° to each other in a plane perpendicular to the main axis of the cylindrical body. The ball retainer 4 is held by the pressure spring 21 located in the nut 22, rigidly fixed by welding to the cylindrical body 1, and the pressing force is changed by the adjusting bolt 23 (see Fig. 4b ). The pressure created in the combustion chamber to disrupt the projectile depends on the pressing force, thus it is possible to adjust the force of the source.

The cone stopper 5 is attached to the cylindrical body 1 with six conical screws without a cap for the hexagon 24 and is designed to stop and fix the "bouncing" cylindrical body, which should eliminate the second blow associated with the landing of the body (see Fig 5 a ). The lift height of the cone stopper is selected in such a way that the “jumping” cylindrical body does not drag the cylindrical cup along with it, but at the same time, the “jump” height is sufficient to stop the cylindrical body due to the “jamming” of the cone stopper associated with it in the flange 25 fixed bolted connection with a flange 26 connected by a weld to a cylindrical cup 27 (see Fig. 5 b and Fig. 6).

Cylindrical cup 27 serves to transfer the momentum from the projectile to the ground and, in addition to the elements described above, includes a shock pad 28 and openings for releasing compressed air 29 (see Fig. 6).

In this case, the shock pad 28 is removable, which makes it possible to use shock pads with different surface areas and thereby allows you to expand and adjust the spectrum of the excited vibrations.

Massive cylindrical projectile 30 is a solid cylinder of a certain shape (see Fig. 7). The shape of the projectile is determined by the solution of three problems:

1. Holding the projectile at the top point due to the presence of a groove 31 for the ball retainer 4;

2. The force of impact due to the mass of the projectile;

3. The projectile fits snugly against the combustion chamber, thereby being part of it.

The claimed mobile pulse source of elastic oscillations is a device for long-term reuse. Consumables are only blank cartridges.

When working out the excitation point, direct direct contact of the operator with the device is not required.

The device can be used without restrictions in any soil and under any weather conditions, except for thunderstorms.

The design of the device provides for the possibility of adjusting the force of impact on the ground and changing the spectrum of excited vibrations.

A mobile pulsed source of elastic vibrations in this design ensures the achievement of the technical result.

The proposed device works as follows.

The device is used in field seismic surveys. The device can be installed at the point of excitation, both on the surface of the earth and in a shallow well for the purpose of closer contact with the ground. In the downhole version, a well with a diameter of 150 mm and a depth of 0.3-0.4 m is drilled at the excitation point with a manual or portable motor-drill. The proposed source of vibrations is installed in the well. At the command of the seismic station operator, the source operator, being at a distance of 5-10 m from him, pulls out the latch of the striker 15, using the cord 20 attached to it, after which the special blank cartridge is initialized. The gases released during the sharp combustion of smokeless powder tear off the massive cylindrical projectile 30 from the ball retainers 4 and accelerate it inside the body 1. The massive cylindrical projectile hits the shock pad 28, thereby exciting elastic vibrations in the soil. In this case, the air compressed by the projectile is removed through the holes 29, and the body 1 "bounces" according to the law of conservation of momentum and gets stuck in the flange 25 due to the conical stopper 5 associated with it (see Fig. 8).

After working out the physical observation, the source is recharged.

The operator unscrews the combustion chamber 3 and the body of the initialization device 9, to which the remaining elements of the initialization device are attached, turns the body 1 over and, hitting it on a wooden plate, returns the massive projectile to its original position, while controlling its fixation with the help of ball clamps 4, then removes spent cartridge case of a blank cartridge, inserts a new cartridge, cocks the striker 12, unhooks the initialization cord 20 from the striker lock 15 and collects the source in the reverse order. After that, the operator installs the source at the point of excitation, hooks the initialization cord 20 to the latch of the striker 15, moves to a safe distance for excitation and transmits a readiness signal to the operator of the seismic station.

To operate the device, specially equipped blank cartridges in a 12-gauge plastic sleeve with a charge of smokeless powder intended for use in hunting shotgun cartridges are used.

The claimed device is intended for carrying out seismic surveys to study the upper part of the geological section by the methods of refraction and MSC.

The claimed device can be used repeatedly, allows you to abandon the transport equipment, eliminating the need to prepare technological passages, thereby reducing the financial and time costs for the production of work, as well as the burden on the environment, and therefore, is industrially applicable.

Sources of information

1. Seismic sources of the company GEODEVICE [Electronic resource] URL: https://geodevice.ru/main/seismic/sources/.

2. Nikitin V.N. Fundamentals of engineering seismic. - M., Publishing House of Moscow State University, 1981.

3. Shneerson M.B., Maiorov V.V. Ground seismic exploration with non-explosive sources of vibrations. - M.: Nedra, 1980.

4. Nalagai V.V., Popov A.Ya., Dick P.I. Seismic exploration of shallow depths. - M.: Nedra, 1989.

5. Patent of the Russian Federation No. 2322685, class. G01V 1/147, 2006.

6. Patent of the Russian Federation No. 2246740, class. G01V 1/147, 2002.

7. Portable compact source of seismic signals "Kvant" [Electronic resource] URL: http://nil-6.narod2.ru/rek/doc_12.html.

8. Exploration from A to Z [Electronic resource] URL: http://gseis.ru/our-business/field-seismic-works/impulse-technique/.

9. Miller R.D., Pullan S.E., Waldne J.S., Haeni F.P. Field comparison of shallow seismic sources // Geophysics. 1986. V.51, P.2067-2092.

10. Patent for invention RU 2439620 C1, 01/10/2012. Application No. 2010124548/28 dated 06/15/2010.

Claims (1)

Mobile impulse source of elastic vibrations, consisting of a massive cylindrical projectile, a cylindrical body equipped with a projectile retaining device and a conical stopper, a cylindrical cup with a replaceable shock platform and holes, a flange connection between the body and the cup, a combustion chamber, an initialization device, characterized in that the massive cylindrical the projectile is an integral part of the combustion chamber, to which an initialization device is attached by a threaded connection, consisting of a striker with a groove and a thread for an eye nut, two springs, a striker lock, a striker cover and an initialization cord, while the cone stopper is attached to the cylindrical body with cone screws, and the projectile holding device consists of three ball clamps, the axes of which are located at an angle of 120 ° to each other in a plane perpendicular to the main axis of the cylindrical body, and the ball clamps are held by clamping springs located in nuts, rigidly closed captive to the cylindrical body, and the pressing force of the springs is regulated by adjusting bolts interacting with their external threads with the internal threads of the nuts.

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