SU586726A1 - Source of seismic signals for water body - Google Patents

Abstract

SOURCE OF SEARCHAL SIGNALS FOR AQUATORIES, containing a combustion chamber formed by two movable plates hermetically connected along the periphery of a flexible element, an initiation source, characterized in that, in order to increase the depth of seismic section research, an additional initiation source is inserted into the combustion chamber .4 movable contact plates with adjustable-: gap between them.

Description

The invention relates to the field of marine seismic prospecting and is a source of excitation of acoustic oscillations in water by detonation of a hydrogen-oxygen gas mixture.

Improvement of sources that use gaseous mixtures in argas goes both along the path of partitioning the first and second pressure waves and increasing their intensity in the seismic pressure range.

A source of elastic oscillations is known, containing a rigid perforated cylindrical explosion chamber with a tightly fitting flexible shell that, after detonation of the gas mixture in a rigid chamber, expands rapidly, thereby creating an elastic impulse.

At the moment when the flexible shell returns to its initial state, the sparking chamber is connected to a vacuum volume, sucking the combustion products and preventing the formation of repeated shocks. Such a source increases efficiency, but is structurally complex and requires a vacuum source. In addition, the pulse power (with other conditions being equal) with extensions is less than with collapse, and the pulse during expansion is not constant in amplitude, which causes distortion of the seismic signal. Also known is a source containing two metal plates connected along the edges with a durable rubber ring. The compressed air is pumped into the cavity of the source, and under the action of the pressure of the plate is dispersed and then fixed in the unfolded state. After that, the source cavity communicates with the vacuum (or the air is pumped out), and the source is ready for operation. To effect the pulse, the plates need to be released and they are instantly slammed into a hydrostatic liquid column, initiating an elastic pulse. Such a source is widely used, but it is characterized by complexity. the design of the plate clamps in the diluted state, as well as the possibility of a pulsation, if the discharge is created below 100 mm | ppm; the closest to the invention in its technical essence is the source of seismic signals for the waters, containing a combustion chamber m, hermetically connected peripherally by a flexible element. The movable plates are provided with restriction restraints, for example, a flexible element. The source is supplied with a pre-chamber communicated with the chamber via a check valve. at the moment of the maximum approaching of the chamber surfaces, the addition of the introduced portion of gas is initiated. Additional gas is introduced into the cavity when, as a result of the rapid condensation of the products, a vacuum is generated. The counter-pressure wave from the explosion of the additional gas, summed with the pressure wave resulting from the cutting of the mountain, the water rushing into the flow cavity, generates a high-intensity compression wave in the medium. However, even such a source design does not provide a depth of seismic section investigation, since the possibility of controlling the pulse shape of the excitable signals is limited. The purpose of the invention is to increase the depth of the seismic section investigation. This is achieved by the fact that an additional source of initiation is introduced into the combustion chamber of the proposed source in the form of contacts mounted on movable plates with a controlled gap between them. In the drawing, schematically show the seismic signal source for aquatic areas. The proposed source consists of plates 1 and 2, connected along the perimeter of the flexible element 3. The plates are provided with shock absorbers 4 and a limiter 5 of divergence, for example, in the form of a cable. In addition to the main initiator 6 (for example, electric glow), a drawing 7 shows contacts 7 with an adjustable gap of an additional initiator 8. The main and additional initiators are connected to an electrical source of initiation (not shown in the drawing). Plate 1 is equipped with a pre-chamber 9 with a check valve 10. Pre-chamber 9 is connected via a controlled valve 11 and pipeline 12 to a gas mixture generator. To the plate 2 through the outlet fitting 13 is connected to a check valve throttle 14. The source works as follows. The explosive gas mixture of hydrogen and oxygen enters through pipe 12 and controlled valve 11 (at this moment it is open) to prechamber 9 and through check valve 10 to the combustion chamber formed by plates 1 and 2 and flexible element 3. Under gas pressure plate 1 and 2 is diverted by a distance equal to the stop 5 divergences. After that, the throttle valve 14 is opened and the combustion chamber is purged from the gas and moisture present in it and from the previous explosion. At the end of the purge, the controlled valve 11 closes, and consequently, the choke valve 14 closes. Thus, certain volumes of gas are filled in the source chamber and in the ancestor 9, but since they have the same pressure, the check valve 10 is closed, thereby separating the cavities of these chambers. The condition of pressure (and hence of volume) from explosion to explosion is maintained due to the presence of a valve-throttle. Purging the chamber with a dry gas in front of the chamber with a subsequent explosion allows to dry its cavity. After purging the source is ready for operation. When an electric pulse is applied to the main initiator 6 in the combustion chamber, the detonating gas is converted into water vapor, followed by the rapid formation of a vacuum. Plates 1 and 2 are acted upon by the action of external hydrostatic pressure;

5586

for the surrounding masses of water. At this moment, under the action of the vacuum, the check valve 10 is automatically opened, and an additional portion of rattling gas enters the combustion chamber from the pre-chamber 9. Plates 1 and 2, converging, compress additional gas and shock absorbers 4. At the moment, - defined; closure of the contacts 7 is the initiation of additional gas. The pressure wave from the explosion of the additional gas is directed oppositely, therefore the intensity of the excitation of the signals increases sharply. The vacuum formed after the additional explosion keeps the plates 1 and 2 in a closed state, thus eliminating the repeated rejection of the latter by shock absorbers 4.

Due to the fact that the plates 1 and 2 are held by the limiters during the explosion of the gas, the first pressure wave is significantly weakened in the seismic frequency range, and the second wave (collapse of the evacuated cavity with a subsequent oncoming explosion) forms a signal of increased amplitude.

The proposed seismic source for waters according to the present invention allows a single pressure wave to be extracted, while increasing its intensity. By shifting in time the moment of ignition of the additional gas, one can change the duration and shape of the total pressure pulse, and hence its spectrum.

The trigger signal can be shifted in time either by changing the gap between the contacts 7, or by any other known method (for example, using a moving multivibrator by charging an electrical capacitance to a certain voltage, etc.). Such features of the source allow improving the quality of the received seismograms and increasing the depth of the study of the seismic section.

"Have

Claims (1)

E54) SOURCE OF SEISMIC SIGNALS FOR AQUATORIES, containing a combustion chamber formed by two movable plates hermetically connected around the periphery of a flexible element, an initiation source, characterized in that, in order to increase the depth of investigation of the seismic section, an additional initiation source is introduced into the combustion chamber in the form of movable plates of contacts fixed to A with an adjustable gap between them.