WO2000033107A1

WO2000033107A1 - Method for searching a hydrocarbon pool (variations), method for monitoring a hydrocarbon pool usage, method for monitoring a filling level of a subsurface gas storage, and seismic oscillation receiver

Info

Publication number: WO2000033107A1
Application number: PCT/RU1999/000398
Authority: WO
Inventors: Sergei Aroutiounov; Edward Gendelman; Boris Grafov; Sergei Karnaukhov; Oleg Kuznetsov; Jury Sirotinski; Haim Sokolin
Original assignee: Sergei Aroutiounov; Edward Gendelman; Boris Grafov; Sergei Karnaukhov; Oleg Kuznetsov; Jury Sirotinski; Haim Sokolin
Priority date: 1998-11-30
Filing date: 1999-10-21
Publication date: 2000-06-08
Also published as: AU6490099A; RU2161809C2

Abstract

The present invention relates to the field of geophysical hydrocarbon detection methods. It can be used in oil and gas deposit research and in the control of hydrocarbon/water boundary movement. The invention is implemented by recording hydrocarbon-generated low-frequency seismic vibrations.

Description

METHOD FOR SEARCHING A HYDROCARBON POOL (VARIATIONS), METHOD FOR MONITORING A HYDROCARBON POOL USAGE, METHOD FOR MONITORING A FILLING LEVEL OF A SUBSURFACE GAS STORAGE, AND SEISMIC OSCILLATION RECEIVER

The invention relates to the seismic research field and can be used for searching hydrocarbon pools at land and shelf, for producing hydrocarbons, and also for storing a natural gas in natural subsurface storages.

At present, substantially all the works associated with a search of hydrocarbon deposits are connected with a seismic prospecting. Conventionally, the seismic prospecting is a recording of a propagation of seismic oscillations being generated in the earth's crust with a subsequent mathematical treatment of obtained data. Seismic prospecting techniques known at the present time utilize usually a recording of a passage of seismic oscillations having frequency more than 100 Hz. During a time of usage of such frequencies in the seismic prospecting a hardware for generating and recording such oscillations, and also a body of mathematics for treating data have been developed sufficiently wide. Either vibrators, or explosions are preferably used to generate such oscillations. To carry out blasting it is necessary to drill blast-holes for charging an explosives. Such technology very adversely affects the ecology state in a search zone. Moreover, when using known methods and techniques of the seismic prospecting, a successfulness prediction factor does not exceed the value of 0.5. Consequently, at least every second borehole drilled in accordance with the conventional seismic prospecting of oil and gas deposits proves to be erroneously laid. Besides means wasted for drilling the borehole, an irreparable and ungrounded damage is inflicted to the environment therewith.

A method for seismic prospecting is known (SU author's certificate N° 949574), comprising steps of: forming seismic oscillations in search zones, recording an information signal with the subsequent mathematical treatment of the recorded signal, the signal being recorded using at least two three-component seismic oscillation receivers spaced some distance apart. A low accuracy has to be considered as a drawback of the known method.

A method is also known for vibration seismic prospecting when searching oil and gas deposits (RU patent Ns 2045079) comprising steps of: exciting seismic oscillations by a seismic vibrator, recording a seismic signal by three-component receivers and mathematical treating the seismic signal, seismic oscillations being excited in a frequency range of 1 to 20 Hz during at least 3 minutes, the step of recording seismic oscillations is performed during at least 20 minutes before exciting seismic oscillations and no more than 5 minutes after finishing the excitation of seismic oscillations, a seismic background was proposed to be recorded as the seismic signal, and a presence of oil and gas deposit was judged by increasing an area under a curve of a mutual spectrum of components with same name when recording the seismic background after exciting seismic oscillations in comparison with recording before the excitation. A low accuracy has to be considered as a drawback of the known method.

An object of the invention is to develop more accurate method for searching a hydrocarbon pool on land and shelf. One more object of the invention is to develop a method for monitoring a hydrocarbon deposit usage.

Yet one more object of the invention is to develop a method for monitoring a filling of a subsurface natural gas storage.

And yet one more object of the invention is to develop a seismic oscillation receiver for recording oscillations of the infra sound frequency range through all recorded components simultaneously.

To provide a search of a hydrocarbon pool at land, in accordance with a so called «passive» variation, there have been proposed the following steps of: disposing, over an assumed pool, at least one seismic oscillation receiver capable of recording oscillations in the infra sound frequency range in at least one component; and recording, simultaneously by all used receivers, a spectral characteristic of the earth's microseismic noise at frequencies of 2 to 5 Hz in all components being measured as an information signal. Preferably, the recording of the information signal is repeated in other points over an assumed pool location. Then, a step of judging the presence of the hydrocarbon pool by appearing a spectral anomaly of the information signal at measured frequencies relative to the information signal for a section involving no pool deliberately is performed. When realizing the method, it is preferably to perform the recording of the information signal during no more than 60 minutes. When using at least two seismic oscillation receivers, they are spaced no more than 500 m apart. A type of seismic oscillation receivers as well as their number, on condition of their ability to record oscillations in the infra sound frequency range, have no influence on achieving the indicated object.

In accordance with a second, «active» variation of realizing the invention, in searching the hydrocarbon pool at land there have been proposed the following steps of: generating seismic oscillations by means of a vibrator; recording an information signal using at least one seismic oscillation receiver capable of recording oscillations in the infra sound frequency range, and also capable of recording simultaneously at least one of components, with a subsequent mathematical treatment of obtained data; therewith using a spectral characteristic of the earth's microseismic noise as an information signal, which spectral characteristic being recorded both before and during the step of generating seismic oscillation; and judging the presence of the hydrocarbon pool by appearing a spectral anomaly of the information signal at frequencies of 2 to 5 Hz at least in one of components at the step of recording the information signal during the step of generating oscillations relative to the information signal recorded before the step of generating oscillations.

When realizing the invention it is possible to have a step of additional recording the information signal yet after the step of generating oscillations. A time for recording the information signal is preferably no more than 20 minutes before the step of generating seismic oscillations, a duration for exciting seismic oscillations by the vibrator is preferably at least 3 minutes, and it is desirable to terminate the step of recording the information signal not later than 5 minutes after terminating the step of exciting seismic oscillations by the vibrator. When using at least two seismic oscillation receivers, it is desirable to space them no more than 500 m apart. And therewith, it is desirable to space said receivers and the vibrator no more than 500 m apart.

When searching the hydrocarbon pool at shelf, in accordance with a «passive» variation, there have been proposed a step of disposing, at a water area bottom, a seismic oscillation receiver capable of recording oscillations in the infra sound frequency range, and also a step of simultaneously recording one and more components, and a step of recording an information signal, a spectral characteristic of the earth's microseismic noise being used as the information signal, and a measurement of the information signal being performed simultaneously at frequencies of 2 to 5 Hz in all measured components, and then a step of judging the presence of the hydrocarbon pool by appearing a spectral anomaly of the information signal at frequencies of 2 to 5 Hz relative to the information signal for a shelf section involving no pool deliberately is performed.

In this case it is preferable to measure the information signal at least 40 minutes. In the case of using at least two seismic oscillations receivers, it is desirable to space them no more than 500 m apart.

When searching the hydrocarbon pool at shelf, in accordance with a «active» variation, there has been proposed a step of disposing at least one seismic oscillation receiver capable of recording at least one component and capable of recording oscillations in the infra sound frequency range at a water area bottom. Then a step of recording an information signal, a spectral characteristic of the earth's microseismic noise being used as the information signal, is performed simultaneously in all measured components using at least one seismic oscillation receiver, and then a step of generating acoustic oscillations in an aqueous medium is performed, continuing the step of recording the information signal in all measured components and teπninating this step after terminating the step of generating oscillations. Then a step of judging the presence of the hydrocarbon pool by appearing a spectral anomaly at frequencies of 2 to 5 Hz in the information signal recorded during the step of generating oscillations and, perhaps, after its terminating relative to the information signal spectral characteristic obtained prior to the step of generating oscillations is performed. When mapping the pool, the afore-cited operation cycle is performed also in other points of an outlined profile. The oscillations are preferably generated during at least 5 minutes. Preferably, the step of recording the information signal is started at least 10 minutes prior to a start of the step of generating oscillations, and is terminated at least 5 minutes after an end of the step of generating oscillations. In the case of using at least two receivers it is preferable to space them no more than 500 m apart at the bottom, and to dispose a recording station substantially in the midway between them on the water surface. Mentioned modes and parameters of the process realization are defined by particular conditions of the search region, and also by the used equipment.

When monitoring a hydrocarbon pool usage there are proposed the following steps of: choosing monitoring points over the deposit; disposing, in said points, seismic oscillation recording receivers, each capable of measuring at least one component in the infra sound frequency range; and recording periodically a spectral characteristic of the earth's microseismic noise at frequencies of 2 to 5 Hz, therewith judging on passing a hydrocarbon contact under the monitoring point at the deposit surface by a disappearance of a spectral anomaly of the earth's microseismic noise at frequencies of 2 to 5 Hz, which disappearance takes place relative to the spectral characteristic of the earth's microseismic noise for a section involving no hydrocarbon under it deliberately. Preferably, the step of recording the spectral characteristic of the earth's microseismic noise is performed during the time of 40 to 60 minutes. The seismic oscillation receivers are preferably disposed near operating holes. It is possible to generate seismic oscillations additionally for at least 5 minutes. In this case, the step of recording the spectral characteristic of the earth's microseismic noise is performed prior to, during, and after the step of generating oscillations, and the step of judging on passing the contact under the monitoring point at the deposit surface is performed by results of comparing spectral characteristics recorded prior to and after (or during) the step of generating.

In monitoring a filling level of a subsurface gas storage there are proposed the following steps of: choosing monitoring points at the earth's surface over the gas storage, which monitoring points define approximately different levels of the gas storage filling; disposing, in said chosen points, at least one seismic oscillation receiver capable of recording oscillations in the infra sound frequency range on at least one component; periodically measuring, while producing the gas from the gas storage, a spectral characteristic of the earth's microseismic noise in the monitoring points; and judging the absence of the natural gas in the gas storage under the point of the monitoring by an absence of the spectral anomaly of the earth's microseismic noise at frequencies of 2 to 5 Hz relative to a section disposed outside the gas storage deliberately. The step of recording the spectral characteristic of the earth's microseismic noise is preferably performed during of 40 to 60 minutes. It is possible to perform additionally a step of generating seismic oscillations in the infra sound range. In this case the step of recording the spectral characteristic of the earth's microseismic noise is performed prior to and during said step of recording. Once the gas have been completely produced from the gas storage, it is desirable to ascertain the point of the monitoring corresponding to the complete producing of the gas. Moreover, once the gas storage is completely filled, it is desirable to ascertain the point corresponding to the complete filling of the gas storage.

In order to realize the offered methods, there has been proposed to use a seismic oscillation receiver capable of recording oscillations in the infra sound frequency range and involving at least one seismic oscillation transducer disposed at a rigid base, seismic oscillation transducers being used capable of recording infra sound oscillations, sensitivity axes of said transducers are set at fixed angles to the flat rigid base and to one another, each transducer being connected to a recording unit, and the base with transducers being placed in a rigid sealed housing.

It is preferable the recording unit to involve a signal preamplifier, amplitude-frequency characteristic former and final amplifier connected in series.

Any transducers of linear and angular oscillations can be used capable of recording oscillations in the infra sound frequency range.

Hereinafter, the spectral anomaly means an increasing of an amplitude value of the spectral characteristic of the earth's microseismic noise at frequencies of 2 to 5 Hz in several times relative to a microseismic noise amplitude value measured over the place where a pool is absent deliberately.

Further the invention will be illustrated by following examples.

When searching a hydrocarbon pool at land in accordance with the conditionally named «passive» variation, over a place of the supposed pool, seismic oscillation receivers are disposed capable of recording oscillations in the infra sound frequency range on at least one component. It is preferable to use the receivers which structure is cited above. A distance between the seismic oscillation receivers is of 450 to 500 m in the case of using simultaneously at least two receivers. The step of recording the spectral characteristic of the earth's microseismic noise is performed during 20 minutes. A view of the spectral characteristic of the earth's microseismic noise for a section involving no hydrocarbon pool deliberately is depicted in Fig. 1. After recording the spectral characteristic of the earth's microseismic noise, the receivers are brought to new points of measure keeping the same conditions of disposing the receivers, and the process of recording the spectral characteristic of the earth's microseismic noise is repeated. Fig. 2 depicts a view of the spectral characteristic of the earth's microseismic noise, which is recorded over the hydrocarbon pool. It is distinctly clear that an amplitude value for frequencies of 2 to 5 Hz in Fig. 2 exceeds significantly an amplitude value for the same frequencies in the case when the pool is absent. The drilling in the point with an observed spectral anomaly had confirmed the presence of the hydrocarbon pool.

When searching a hydrocarbon pool at land in accordance with the conditionally named «active» variation, over a place of the supposed pool, at least one acoustic oscillation receiver is disposed capable of recording infra sound oscillations on at least one component; then the step of recording the spectral characteristic of the earth's microseismic noise is performed during preferably 20 minutes (the spectral characteristic of the recorded earth's microseismic noise is depicted in Fig. 3); after that a seismic vibrator is switched on, and, without finishing the step of recording the spectral characteristic of the earth's microseismic noise, seismic oscillations are generated during approximately 3 minutes (the spectral characteristic of the recorded earth's microseismic noise over the pool is depicted in Fig. 4). The step of recording the spectral characteristic of the earth's microseismic noise may be continued also after finishing the step of generating the oscillations. When recording the spectral characteristic of the earth's microseismic noise in the case of using more than one seismic oscillation receiver, these receivers are spaced of 450 to 500 m apart and at a distance of 450 m from the seismic vibrator. From the comparison of Fig. 3 and Fig. 4 respectively it follows that an amplitude value of the amplitude-frequency characteristic, at frequencies of 2 to 5 Hz in Fig. 4, exceeds approximately three times an amplitude value in Fig. 3. The drilling performed in the places of recording the spectral characteristic of the earth's microseismic noise, to which places the relationships depicted in Fig. 3 and 4 correspond, has shown the presence of the hydrocarbon pool in the point having the spectral characteristic anomaly.

When searching a hydrocarbon pool at shelf in accordance with the conditionally named «passive» variation, onto the water area bottom preferably from self-propelled floating means, at least one seismic oscillation receiver is disposed capable of recording infra sound oscillations on at least one component, and the step of recording the spectral characteristic of the earth's microseismic noise is performed simultaneously on all measured components. The step of recording is performed preferably during at least 30 minutes. In the case of using more than one receiver, these receivers are spaced of 450 to 500 m apart. In this case it is usual to dispose the point of recording on the water surface approximately at equal distance from all seismic oscillation receivers being in use. The spectral characteristics of the earth's microseismic noise, measured outside and over the pool, are substantially similar to characteristics depicted in Fig. 1 and 2. The drilling performed in the place of recording the spectral characteristic of the earth's microseismic noise, which is substantially the same with Fig. 2, has shown the presence of the pool.

When searching a hydrocarbon pool at shelf in accordance with the conditionally named «active» variation, onto the water area bottom preferably from a self-propelled floating means, at least one seismic oscillation receiver is sunk capable of recording oscillations in the infra sound frequency range on at least one component, and the step of recording the spectral characteristic of the earth's microseismic noise is performed. Without finishing the step of recording the spectral characteristic of the earth's microseismic noise, a step of generating acoustic oscillations is performed. A view of the spectral characteristic of the earth's microseismic noise, recorded prior to the step of generating oscillations, is substantially similar to Fig. 3. A view of the spectral characteristic of the earth's microseismic noise, recorded in the presence of the hydrocarbon pool, after generating the acoustic oscillations is substantially the same with Fig. 4. It is preferable to perform the recording of the spectral characteristic of the earth's microseismic noise prior to the start of generating during at least 10 minutes. The step of generating acoustic oscillations is performed preferably during approximately 5 minutes. In the case of using more than one seismic oscillation receiver, it is recommended to space them approximately 500 m apart. In this case it is preferable to dispose the recording point at equal distance from all seismic oscillation receivers. The step of recording the spectral characteristic of the earth's microseismic noise may be continued also after f ishing the generating of the acoustic signal. For monitoring a hydrocarbon pool usage, monitoring points are chosen over the pool, preferably disposing them near operating holes.

In the chosen points, seismic oscillation receivers are disposed capable of recording seismic oscillations in the infra sound frequency range on at least one of components. The spectral characteristic of the earth's microseismic noise is recorded periodically. Once a spectral characteristic anomaly disappears at frequencies of 2 to 5 Hz, the step of judging is performed on passing a water-hydrocarbon contact under the monitoring point. The spectral characteristic anomaly is defined in relation to the spectral characteristic of the earth's microseismic noise, recorded for a section lying deliberately not over the pool. It is preferable to perform the step of recording the spectral characteristic of the earth's microseismic noise during of 40 to 60 minutes for every point. It is possible to generate additionally the seismic oscillations in the zone of operating holes. In this case the step of recording is made both prior to and during, and also, possibly, after the step of generating.

When monitoring a filling level of a subsurface gas storage, points are chosen on the earth's surface, which defines approximately different levels of the gas storage filling; in the chosen points, seismic oscillation receivers are disposed capable of recording infra sound oscillations on at least one component; and the spectral characteristic of the earth's microseismic noise is recorded periodically, the absence of an anomaly of the spectral characteristic of the earth's microseismic noise at frequencies of 2 to 5 Hz being indicative of the absence of the natural gas under the monitoring point. In order to perform the step of comparing, the spectral characteristic of the earth's microseismic noise is recorded by the similar receiver over a place disposed deliberately outside the gas storage. It is preferable to choose monitoring points at the first filling of the gas storage, determining places in which the presence of the natural gas is recorded at different quantities of a supplied gas. However, in any case, the monitoring points are determined by experiment. It is desirable to perform the step of recording the spectral characteristic of the earth's microseismic noise during approximately 50 minutes. It is possible to perform the step of generating seismic oscillations during the step of recording. In this case, the step of recording is performed both prior to starting the step of generating and during the step of generating.

In order to realize the above-stated methods, it has been suggested to use a seismic oscillation receiver capable of recording oscillations in the infra sound range, said receiver comprising at least one seismic oscillation transducer capable of recording infra sound oscillations, all used transducers being disposed at a rigid base in such a way that ensitivity axes of these transducers are set at fixed angles to the flat rigid base and to one another, every transducer being connected to a recording unit, and the base with transducers being placed in a rigid sealed housing. It is possible to use the angular and/or linear oscillation transducers capable of recording oscillations in the infra sound frequency range. It is preferable to use piezoelectric, conductivity-measuring, or moving-coil transducers. The recording unit of every transducer comprises preferably a signal preamplifier, amplitude-frequency characteristic former and final amplifier connected in series, each final amplifier being made with a possibility to couple with a common recorder.

An application of this invention will allow to increase an accuracy in determining the presence of a hydrocarbon pool.

Claims

1. A method for searching a hydrocarbon pool at land, comprising a step of recording an information signal at least one time using at least one seismic oscillation receiver capable of recording at least one component, characterized in that a spectral characteristic of the earth's microseismic noise is used as the information signal, which spectral characteristic being measured using the seismic oscillation receivers capable of recording at least one component, and also capable of recording seismic oscillations in the infra sound range, the step of recording the information signal being performed at frequencies of 2 to 5 Hz simultaneously on all components being measured, and a step of judging the presence of the pool is performed by appearing a spectral anomaly of the information signal relative to a section involving no pool deliberately.

2. The method according to the claim 1, characterized in that the step of recording the information signal is performed no more than 60 minutes.

3. The method according to the claim 1, characterized in that when using at least two seismic oscillation receivers, they are spaced no more than 500 m apart.

4. A method for searching a hydrocarbon pool at land, comprising a step of recording an information signal using at least one seismic oscillation receiver with a subsequent mathematical treatment of obtained results, characterized in that a step of generating the seismic oscillation by a seismic vibrator is performed additionally, a spectral characteristic of the earth's microseismic noise is used as the information signal, the step of recording the information signal is performed both prior to and during the step of generating the seismic oscillations in a frequency range of 2 to 5 FLz using seismic oscillation receivers capable of recording oscillations in the infra sound range on at least one component, and a step of judging the presence of the pool is performed by appearing a spectral anomaly of the information signal at frequencies of 2 to 5 Hz on at least one of the components at the step of recording the signal during the step of generating the oscillations relative to the information signal measured prior to the step of generating.

5. The method according to the claim 4, characterized in that the step of recording the information signal is performed prior to the step of generating the oscillations during no more than 20 minutes.

6. The method according to the claim 4, characterized in that the step of generating the oscillations is performed at least 3 minutes.

7. The method according to the claim 4, characterized in that when using at least two seismic oscillation receivers, they are spaced no more than 500 m apart.

8. The method according to the claim 4, characterized in that the seismic oscillation receivers are disposed no more than 500 m from the seismic vibrator.

9. A method for searching a hydrocarbon pool at shelf, comprising steps of: disposing a seismic oscillation receiver at the bottom, and recording an information signal, characterized in that a spectral characteristic of the earth's microseismic noise is used as the information signal, which spectral characteristic being measured using at least one seismic oscillation receiver capable of recording simultaneously at least one component, and also capable of recording seismic oscillations in the infra sound frequency range, the step of recording the information signal being performed at frequencies of 2 to 5 Hz simultaneously on all components being measured, and a step of judging the presence of the pool is performed by appearance of a spectral anomaly of the information signal relative to a section involving no pool deliberately.

10. The method according to the claim 9, characterized in that the step of recording the signal is performed at least 40 minutes.

11. The method according to the claim 9, characterized in that when using at least two seismic oscillation receivers, they are spaced no more than 500 m apart.

12. A method for searching a hydrocarbon pool at shelf, comprising steps of: disposing a seismic oscillation receiver at the bottom, generating acoustic oscillations, and recording an information signal, characterized in that at least one seismic oscillation receiver is used capable of recording one and more components and also oscillations in the infra sound frequency range, a spectral characteristic of the earth's microseismic noise is used as the information signal, the step of recording the information signal being performed at frequencies of 2 to 5 Hz simultaneously on all components being measured both prior to and during the step of generating the acoustic oscillations, and a step of judging the presence of the hydrocarbon pool is performed by appearing, at frequencies of 2 to 5 Hz, a spectral anomaly of the information signal being recorded during the step of generating the acoustic oscillations relative to the information signal measured prior to the step of generating the oscillations.

13. The method according to the claim 12, characterized in that the step of recording the information signal is started at least 10 minutes prior to starting the step of generating the seismic oscillations.

14. The method according to the claim 12, characterized in that when using at least two seismic oscillation receivers, they are spaced no more than 500 m apart.

15. The method according to the claim 14, characterized in that the seismic oscillation receivers are disposed at approximately equal distance from a station for recording the information signal.

16. The method according to the claim 12, characterized in that the step of generating the acoustic signal is performed during at least 5 minutes.

17. A method for monitoring a hydrocarbon pool usage, characterized in steps of: disposing, over the pool in monitoring points, seismic oscillation receivers capable of recording oscillations in the infra sound range on at least one component, recording a spectral characteristic of the earth's microseismic noise periodically in the range of frequencies of 2 to 5 Hz as an information signal, and judging a passage of a hydrocarbon contact under the point on the earth's surface by a disappearance of a spectral anomaly of the information signal, which anomaly occurs relative to the spectral characteristic of the information signal for a section involving no hydrocarbon deliberately.

18. The method according to the claim 17, characterized in that the step of recording the information signal is performed during of 40 to 60 minutes.

19. The method according to the claim 17, characterized in an additional step of generating the seismic oscillations, which is performed during at least 3 minutes.

20. The method according to the claim 19, characterized in that the step of recording the information signal is performed both prior to and during the step of generating the seismic oscillations.

21. A method for monitoring a filling level of a subsurface natural gas storage, characterized in steps of: choosing, at the earth's surface, monitoring points defining approximately different levels of the gas storage filling; disposing, in said chosen points, seismic oscillation receivers capable of recording oscillations in the infra sound frequency range; periodically recording, during the gas storage usage, a spectral characteristic of the earth's microseismic noise in a range of frequencies of 2 to 5 Hz; and deterrnining the absence of the natural gas under the point of the monitoring by an absence of a spectral anomaly of the earth's microseismic noise in said frequency range relative to a section disposed deliberately outside the gas storage.

22. The method according to the claim 21, characterized in an additional step of generating the seismic oscillations is performed during at least 3 minutes.

23. The method according to the claim 21, characterized in that the step of recording the spectral characteristic of the earth's microseismic noise is performed both prior to and during the step of generating the seismic oscillations.

24. The method according to the claim 21, characterized in that the step of recording the spectral characteristic of the earth's microseismic noise is performed during of 40 to 60 minutes.

25. A seismic oscillation receiver capable of recording oscillations in the infra sound frequency range, comprising at least one seismic oscillation transducer disposed at a rigid base, characterized in that said seismic oscillation transducers are capable of recording the infra sound oscillations, sensitivity axes of said transducers being set at fixed angles to the flat rigid base and to one another, each transducer being connected to a recording unit, and the base with transducers being placed in a rigid sealed housing.

26. The receiver according to the claim 25, characterized in that the recording unit comprises a signal preamplifier, amplitude-frequency characteristic former and final amplifier connected in series.