SU760010A1 - Device for exciting elastic oscillations from land surface - Google Patents

Description

The invention relates to the field of seismic exploration, namely, devices for initiating elastic waves from the earth's surface due to the expansion of compressed air in a closed 5 capable, to expand, working volume of the device.

Both in the USSR and abroad, a number of devices are known that are designed to excite oscillations in the soil and which are used for this purpose, either the expansion energy of compressed air or the energy of an explosion of gas explosive mixtures (HWS).

15

For example, the Terrapak device is known to be £ 1}, in which a drummer forced by compressed air is used to impact the ground. This device consists of a massive cylinder (reactive part) and a piston placed in it with a rod, which is connected with a plate by means of a ball joint (impact part). Before impact 25, the impact part is located at a certain distance from the ground surface. To disperse the striker, compressed air is supplied through the quick-start valves “between the piston of the upper roof” and 30

2

What the cylinder, which accelerates the drummer.

The device has sufficient energy of impact up to 11000 kgf-m, satisfactory synchronism and a higher spectrum of the excited signal, compared with the free-falling load.

However, it is difficult both constructively and operationally, since the impactor-piston-plate-plate are also a compressing element for compressing used air from a previous impact. To this end, the device is equipped with high-pressure hydraulic and pneumatic equipment, near / quick-response valves, and large-diameter sealing elements requiring qualified service. In addition, the device has a low survivability drummer / due to the large overloads that occur in its elements at the time of the meeting with the ground. These deficiencies are likely to limit the widespread use of the device in seismic exploration.

It is also known device £ 2], in which to excite oscillations in

3 760010

ground is used exhaust compressed air from a pneumogun, placed in a steel bell, filled with water and equipped with a flexible bottom. The device is installed before the action

. on the ground.

After the airgun has been activated, the impulse from air expansion is transmitted through a layer of water to the flexible bottom and then to the ground. This device also did not find widespread use due to the low impact efficiency caused by the low degree of air expansion and due to the high frequency spectrum. awakened signal. /,_./.·/

Air guns or pneumatic emitters £ h], widely used

currently in the maritime seysmo -.....

exploration, are a cylinder with an air cavity and exhaust holes, which are covered by a hollow piston located in the cylinder. 'The piston opens' or closes' the exhaust hole on command from an electropneumatic valve that provides remote control of the exhaust. Air is supplied to the pneumatic emitter under pressure up to 150 kgf / cm% volume of the air cavity ’in the cylinder.

'7 from 2, 5 to 30 dm ³ , which corresponds to the exhaust energy from 25 to 270 kcal

7 or from 10.7 to 115 thousand kgf-m. The emitters also have a sufficiently high synchronicity of emissions - about + -0.002 s. Pneumatic emitters

'Both the serial production of the USSR was established and tenacious in exploitation. However, their use is possible only in reservoirs. ->

The closest in technical 'essence of the present invention is a device for the excitation of elastic vibrations from the surface of the ground £ 4]. Devices such as "Dinneys"

£ 4] using the energy of the explosion of hot water produced in a closed, capable of expanding the working volume, found the most widely used for

'land seismic exploration both in the USSR and abroad. Such devices

have a sufficiently high impact energy (up to 10-15 thousand kgf-m), high synchronization of impacts (up to + 0.001 s) with the mobility of the design'I and survivability of all nodes.

In these devices, the internal cavity is divided by a piston into two volumes; ma: top - damper, in which 7 air is pumped to preload 7

the piston to the bottom of the liner, and the lower worker, into which the DHW is pumped and where its initiation takes place. Before exposure, the device is installed on the ground and at the time of ini-. for DHW production

'bang through the bottom of the liner

on the ground, without prior acceleration of the shock body sleeve with the bottom.

ten

15

20

25

thirty

35

40

45

55

60

50

four

This device has limited performance at lower temperatures due to the low vapor pressure of propane or propane-gas. ”Tana, used as a fuel, as the most common and affordable gaseous fuel. The device can practically work only at temperatures up to -5®s.

Heating gas components to extend the temperature range of work worsens safety conditions. This limits the use of the device in the winter and in areas of North. The operation of the devices is associated with the constant supply of their combustible gas and oxygen and is possible in areas where established: their production and supply. The latter circumstance / limits the autonomy of the device. In addition, it is difficult to operate the device in a complex with a cumulative reconfiguration device in the automatic mode, since an increased device response rate (number of operations per unit of time) impairs the safety of the installation and may lead to an emergency situation.

. The purpose izobreteniya.yavlyaetsya ^expansion: renye temperature range and easier operation of the device.

This goal is achieved by the fact that inside the piston a pneumatic source rigidly fixed in it is placed in such a way that its outlet opening is located on the end of the piston from the bottom of the sleeve.

• In FIG. 1 shows a device for the excitation of elastic oscillations in the initial state (before exhaust); in fig. 2 - the same after the exhaust.

The device (Fig. 1) contains a sleeve 1 with a flat bottom and top .... a cover 2, a heavy piston 3, which divides the internal / cavity of the sleeve into two volumes,; the lower-working 4 and the upper damping 5, in the central part of the piston a pneumatic cannon pneumatic source 6 is placed, comprising a housing, a hollow / piston 7, which triggers an electropneumatic valve 8 and seals * Body elements' 9. The sleeve 1 has side holes 10 for exhaust air, cover 2 - hole 11 For air into the damper cavity 5. The internal cavity of the pneumatic chamber is divided by a hollow piston: 7 into volumes 1215 (FIG. 2) filled with compressed air and interconnected with a source of compressed air. air, -channels 16-20 and exhaust port 21.

The device works as follows. '

After installing the device on the ground (Fig. 1) and supplying compressed air to the damping volume 5 through the opening 11 of the cover 2, usually under pressure not more than 1.5-2 kgf / cm%

Compressed air (up to 150 kgf / cm ^) is channeled through channel 16 into pneumatic source 6. Compressed air enters through channel into cavity 14 of piston 7, presses down to the bottom of the cavity and moves piston 7 down to the stop. After the piston stops in the lower position, the cavity 14 through the channel 18 communicates with the cavity 13 and compressed air will also fill it. The cavity 12 through the channels 20 in the case of the pneumatic source is constantly communicated to the environment. In the cavity 13 is the main volume of air to be exhausted, and, when it is filled with air, the device is ready for operation.

When a command is sent from the control panel or from a seismic station to an electropneumatic valve 8, the valve opens and compressed air enters channel 17 under the piston shoulder 7, overcomes the force generated by air pressure to the bottom of the cavity 14, and breaks the piston 3 upwards. After the piston breaks off, the exhaust port 21 opens and the air flows from the cavity 13 into the volume 4 and presses on the bottom 22 of the sleeve, transmitting a pressure pulse through the bottom 22 of the sleeve to the ground 23. Under the action of air pressure, the piston 3 will move upwards and when the piston end reaches the exhaust holes 10 of the sleeve 1, the air will be released into the environment. '.

° After exposure, when the air pressure in the pneumatic source and in the working volume of the device drops to a certain value, due to the outflow of air through the holes 10, the force on the piston 7, both from the side of its shoulder and from the bottom of the cavity is ί14 will be balanced. A further decrease in air pressure in the cavities 4, 13 ^ 15, will lead to the predominance of usi760010

6

Lead to the bottom of the piston cavity 14, the hollow * piston 7 will move down and block the exhaust hole 21.

Air will fill the cavity 14, then the cavity 13 of the pneumatic source

5 and, as soon as the piston 3 returns to the air pressure of the damping volume 5 to the initial position, i.e. when the piston 3 touches the bottom of the liner 1, the device is ready for a new release “0.

Using the proposed device To excite elastic oscillations from the surface of the earth, as compared with the existing prototype, allows extending the temperature range of the device’s ⁵ zones of operation, ensuring the autonomy of work and increasing the labor productivity,

20 ·

Claims (1)

Claim . The device "to excite elastic vibrations from the surface of the earth, containing a sleeve with a bottom and a piston, 25 tons of tacho that, in order to expand the temperature range and simplify the operation of the device, a pneumatic source rigidly fixed in it is placed inside the piston in such a way that its exhaust port is located on the piston end the bottom of the sleeve. 35