RU2467357C1 - Ground-based non-explosive pulsed seismic vibrator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to geophysics and can be used in seismic exploration. Disclosed is a seismic vibrator meant for generating seismic waves by deforming the ground half-space from the surface of the earth. The seismic vibrator has a rigid base plate, a balance weight and a pulsed electromagnetic, induction-dynamic or some other type of motor. The force generated by the motor is applied between the base plate and the balance weight (first balance weight). The seismic vibrator is characterised by use of an additional (second) balance weight supported by the base plate, which reduces the level of noise waves generated by the seismic vibrator.

EFFECT: lower speed of movement of the plate after the working cycle where it compresses the ground and intensity of the generated seismic noise waves.

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Description

The invention relates to non-explosive terrestrial pulsed sources of seismic waves used in seismic surveys.

Known seismic source of non-explosive type (Ivashin V.V., Ivannikov N.A. Pulse electromagnetic seismic sources: features and prospects for improvement. The journal "Instruments and systems for exploration geophysics", No. 2, 2005, S. 9-14), containing a rigid plate a radiator supported by a load and an electromagnetic motor, the inductor magnetic circuit with an excitation winding is fixed to the load, and the motor armature is supported on the plate through the racks and is separated from the inductor magnetic circuit by an air gap. When a current pulse is applied to the excitation winding between the armature and the inductor magnetic circuit, a force arises transmitted through the racks to the plate. The plate under the action of this force is shifted in the direction of the soil, while the soil is deformed and a seismic wave is formed in it. The magnetic circuit of the inductor is accelerated upward by the force of the motor, as a result, the gap between the magnetic circuit of the inductor and the armature is selected. At the moment of choosing the gap, the force on the plate ceases, and the accelerated load with the magnetic circuit of the inductor and the armature moves in the field of gravity to a certain height, determined by the speed of the load at the moment of choosing the gap.

Since the soil is a medium with elastic properties, after the compression phase of the soil, its decompression phase begins, during which the plate is accelerated upward by the action of the elastic forces of the soil. As a result of this, the soil is unclenched and the slab, having gained significant speed when unclenching the soil, “flies” above the soil and then falls to the ground, which leads to the creation of a seismic interference wave, which reduces the quality of seismic surveys.

A known (prototype) non-explosive seismic source with a pulse induction-dynamic type motor (RF Patent No. 2369883, BI No. 28, 2009), comprising a rigid emitter plate, a load supported on it and a pulse motor installed with the possibility of generating force between the plate and by load. During the operation of such a seismic source, as in the case of a seismic source adopted as an analog, under the action of force, the plate deforms the soil, and the load accelerates upward. The phase of soil compression is followed by the phase of its decompression and movement (“bounce”) of the plate above the level of its initial position on the ground, and then the plate is re-exposed to the soil, creating a disturbance wave, which reduces the seismic efficiency of the seismic source and the quality of seismic survey work.

The problem to which the invention is directed, is to increase the seismic efficiency of the seismic source. The technical result of the proposed solution is to reduce the speed of movement of the plate after the moment of the working cycle of compression of the soil and the intensity of the generated seismic interference wave.

The mentioned task and the technical result are achieved by the fact that the proposed technical solution comprises a rigid emitter plate supported on it by the first load, a pulse motor with the possibility of applying the force it creates between the emitter plate and the first load, and the second load is supported on the emitter plate.

The invention is illustrated by:

Figure 1 - structural diagram of the proposed seismic source;

Figure 2 - graphs of changes applied to the plate-emitter force, speed and movement of the plate;

Figure 3 - structural embodiment of the second load;

Figure 4 - structural embodiment of a seismic source with a pulsed motor of electromagnetic type;

Figure 5 - structural design of a seismic source with a pulsed motor of the induction-dynamic type.

The seismic source (figure 1) contains a plate-emitter 1, supported on the plate, the first load 2, the source 3 of the pulsed force and supported on the plate the second load 4.

The seismic source works as follows. Under the action of the pulsed force 5 (figure 2), the load 2 is accelerated up, and the plate 1 is down. The speed 6 of the displacement of the plate 1 during the time t _{1 of the} action of the force 5 increases, overcoming the reaction force of the soil, increasing as the plate 7 is displaced. In the time interval from t ₁ to t ₂ , the plate displacement speed 6 decreases to zero, and the kinetic energy of the plate 1 received from the force source 5 is converted into elastic deformation energy of the soil and partially released in the form of energy spent on inelastic soil deformation and the energy of the radiated seismic wave whose intensity is proportional to the square of the speed of displacement 6 (loading) of ground plate 1. plate 1 Return to the initial position in the time interval from t ₂ to t ₃ (step uncompressing ground) occurs with increasing velocity displacements 6 Plate Ia. At time t ₃ , the impact interaction of the plate 1 with the second load 4. occurs. In the inelastic interaction of two masses, the impact velocity of the plate decreases. For example, if the masses of plate 1 and the second load 4 are equal, it will be halved, and half of the kinetic energy of plate 1 will be released into thermal energy during the impact. A decrease in the velocity Δt of the plate 1 upon impact leads to a decrease in the rate of change of soil deformation and, accordingly, the intensity of the interference wave radiated at t greater than t ₃ .

The nature of the impact interaction at time t _{3 of the} plate 1 and the second load 4 is determined by the value of the recovery coefficient, to reduce which the second load (Fig. 3) can be made in the form of a box 8 with a cavity 9, partially filled with metal pieces 10 of spherical shape weighing from 1 to 3 g. When the plate 1 hits the body 8, a part of the shock mechanical impulse acts on the pieces 10 placed in its cavity, therefore the pieces accelerate upwards, act (rub) with each other and with the surface of the box cavity 8, which leads to a decrease recovery coefficient due to the allocation of losses during the movement of the pieces 10.

The second load 4 can be made distributed around the perimeter of the plate 1 or in the form of separate sections placed on the surface of the plate. The box 8 of the second cargo 4 can be made of a material with a small specific gravity, for example, aluminum alloy, plastic, etc. The main influence on the decrease in the speed of movement of the plate 1 during its impact interaction with the second load 4 is exerted by the mass of bulk material 10 placed in the duct.

The pulse engine 3 (Fig. 1), which creates a force effect between the emitter plate 1 and the first load 2, depending on the particular application of the seismic source, can be made hydraulic, pneumatic, electric or other type.

Features of the seismic source in figure 1 for the case of using an electromagnetic type motor in it are shown in the structural diagram of figure 4. The plate 1 is made with racks 11, on which the armature 12 of the engine 3 rests, the magnetic circuit of the inductor 13 of which is fixed with the field winding 14 on the first load 2, supported by its racks 15 on the emitter plate 1. The second load 4 is placed on the plate 1 between the racks 15 first load. The motor inductor 13 and its armature 12 are separated from each other by a working air gap.

When applying a current pulse to the excitation winding 14 between the magnetic circuit of the armature 12 and the magnetic circuit 13 of the inductor of the motor 3 creates a pulse of force 5 (figure 2). Through the struts 11, the force 5 acts on the plate 1, which under the action of this force is displaced in the direction of the soil and creates its deformation 7. The same force 5 accelerates the load 3 upwards during the time from t ₀ to t _{1 the} choice of the gap between the armature 12 and the inductor 13 engine 3. The time t _{1 of the} choice of the gap corresponds to the pulse duration of the force 5. By the time t _{3 the} phase of soil compression (time from t ₀ to t ₁ ) and the phase of its expansion (time from t ₂ to t ₃ ) are completed. At time t ₃ , the plate 1 hits the second load 4, as a result of which the speed 6 of the plate 1 and its kinetic energy decrease, which leads to a decrease in the movement of the plate up above its initial position at t ₀ and the intensity created by t more than t _{3 by the} seismic source seismic wave. To reduce the recovery coefficient when the plate 1 hits the second load 4, it can be made with a cavity inside, in which, for example, pieces of material are placed.

The proposed technical solution (Fig. 1) can be used to create ground-based seismic sources with an induction-dynamic motor (Fig. 5), the use of which can significantly reduce the weight of seismic sources and expand the possibilities of their use in mountainous or marshy areas that are difficult to conduct seismic exploration and etc.

The seismic source (Fig. 5) contains a radiating plate 1, a first load 2 supported on it, which includes a loading mass 15 and a non-magnetic plate 16 made of non-conductive material bonded to it. Pulse induction-dynamic motor 3 contains a field winding 17, placed in the groove of the plate 16, and the motor armature in the form of a plate 18 mounted on the plate 1 of a material of high electrical conductivity, such as copper. The second load 4 is supported on the plate 1.

When a current pulse is supplied to the excitation coil 17, a current is induced in the plate 18 adjacent to it and a force pulse 5 is generated between the excitation coil 17 and the plate 18. In this case, the plate 1 moves in the direction of the soil at a speed of 6 (Fig. 2), ensuring the creation of a deformation 7 soil and seismic wave formation. The first load 2 under the action of force 5 is accelerated upward in the field of gravity. At time t _{3, the} plate 1 with a speed of 6 returns to its original position and its shock interaction occurs with the second load 4. In this case, part of the kinetic energy of the plate 1 is released into thermal energy, and the speed of the plate 1 decreases, which leads to a decrease in the radiation of the seismic wave energy -interference at t greater than t ₃ and increase the efficiency of the seismic source.

Claims (1)

Ground non-explosive pulsed seismic source containing a rigid emitter plate supported on it by the first load, a pulsed motor with the possibility of applying its force between the emitter plate and the first load, characterized in that the second load is supported on the emitter plate.

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