JPS6374229A - Receiver for very long wavelength electromagnetic wave - Google Patents

Abstract

PURPOSE:To eliminate the need for a large sized antenna and to improve the reception sensitivity by providing two plate electrodes opposed to each other and provided on ground and a buried electrode provided underground and connected to one of the plate electrodes so as to detect an electric field with a very long wavelength electromagnetic wave sent from underground. CONSTITUTION:A drill collar 6 is connected to the tip of a drill pipe 4 led from a digging rig 2 via an insulation collar 5 and a bit 7 for digging is fitted to the tip. A transmitter 8 sending underground information is contained in the drill collar 6, its transmission output terminal is connected to the drill pipe 4 and the drill collar 6 connected via the insulation collar 5, the drill pipe 4 and the drill collar 6 constitute the transmission dipole antenna, from which a very long wavelength electromagnetic wave is sent on ground. A receiver R comprising an electric field sensor 20, an amplifier 10 and a signal processing section 11 receiving the electric field component of the electromagnetic wave sent from underground is installed on ground. In such a case, one electrode 20b of the two opposed plate electrodes 20a, 20b of the electric field sensor 20 is connected to the underground buried electrode 30 and a large detection voltage is obtained between the electrodes 20a and 20b.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a receiving device for extremely long wavelength electromagnetic waves. This paper proposes a receiver for wavelength electromagnetic waves.

[Prior art]

When drilling wells for oil, natural gas, etc., it is necessary to obtain underground information on the geology, temperature, pressure, etc. A mud logging method is used to measure the components of mud, which is circulated between the underground and the surface through a drilling pipe during drilling. .

However, these methods require a long time for measurement and cannot measure underground information during excavation in real time. Therefore, recently MWD (Measure-m
Measurement technology aimed at real-time measurement, called ``drilling clock side'', has been researched, and various methods have been proposed.

Among these, methods that use electromagnetic waves are attracting attention.

For example, Figure 3 is based on the American literature “Scream 1 & Gas Jour”.
na185″Feb21.19830GJ Report
t rsecond-GeneratjonMWD
It is a reception status diagram of extremely long wavelength electromagnetic waves that transmit underground information shown in Tool Pa5ses Field Te5tJ.

In Fig. 3, a drilling rig 2 is constructed on the ground 1, and a well 3 is drilled directly below the drilling rig 2, and a drill pipe 4 extends into the well 3. A drill collar 6 is connected to the tip of the drill pipe 4 via an insulating collar 5. A bit 7 for drilling is attached to the tip of the drill collar 6, and the ground 1 is drilled by rotating the drill pipe 4. The drill collar 6 houses a transmitting device 8 that detects temperature, pressure, etc. underground during excavation, and transmits underground information to the surface using a modulated signal converted into an electrical signal.

A transmission output terminal (not shown) of the transmitting device 8 is connected to a drill pipe 4 and a drill collar 6, which are connected with an insulating collar 5 in between, and the drill pipe 4 and drill collar 6 function as a transmitting dipole antenna. It is designed to transmit ultra-long wavelength electromagnetic waves modulated by the radio waves to the ground.

On the other hand, a receiving dipole antenna 9 is installed at the base of the drilling rig 2 on the ground 1, parallel to the ground 1 and positioned in the radial direction from the drilling rig 2, so as to receive extremely long wavelength electromagnetic waves from underground. ing. The signal received by the dipole antenna 9 is input to an amplifier 10, and the amplified signal is input to a signal processing unit 11 for demodulating (detecting) the signal to obtain underground information. In this case, the frequency of the extremely long wavelength electromagnetic waves is often 50 Hz or less, and the wavelength in this case is approximately 6000+a or more. In addition, the strata,
Geology.

Depending on the depth, etc., extremely long wavelength electromagnetic waves with a frequency of about 100 Hz are used.

[Problem that the invention seeks to solve]

In the receiving device for extremely long wavelength electromagnetic waves mentioned above, a dipole antenna with high reception sensitivity is installed, but since the wavelength of extremely long wavelength electromagnetic waves of about 50 Hz is as long as 6000 km, even if the length of the antenna is set to 1/4 of the wavelength λ. The total length of the antenna is 1500 km, which is impossible to put into practical use, and the length of the antenna that can be put to practical use is limited to about 100 km at most. However, since the reception sensitivity is proportional to the effective length of the antenna, there is a problem that in the case of extremely long wavelengths, if the total length of the antenna is shortened, it is not possible to receive a signal with a good S/N ratio.

In view of the above-mentioned problems, an object of the present invention is to provide a receiving device for extremely long wavelength electromagnetic waves with a good S/N ratio by detecting the electric field generated by extremely long wavelength electromagnetic waves without installing a large-scale receiving antenna. shall be.

c Means for Solving Problem] The receiving device for extremely long wavelength electromagnetic waves of the first invention includes a flat plate electrode provided on the ground and a buried electrode provided underground, and detects the electric field between the two electrodes. The configuration is such that information can be obtained from this.

A receiving device for extremely long wavelength electromagnetic waves according to a second aspect of the invention includes two opposing flat plate electrodes provided on the ground, and a buried electrode provided underground and connected to one of the flat plate electrodes. The structure is such that information is obtained by detecting the electric field between the electrodes.

[Effect]

A transmitting device placed underground transmits information to the ground using extremely long wavelength electromagnetic waves. The electric field component due to the extremely long wavelength electromagnetic wave is detected by a flat plate electrode on the ground and an electrode buried underground, and the information is obtained by the signal processing unit based on the change in the electric field detected between the two electrodes.

〔Example〕

The present invention will be explained in detail below with reference to drawings showing embodiments. 1st
The figure is a configuration diagram showing a receiving device for extremely long wavelength electromagnetic waves according to the present invention together with a transmitting device. In Figure 1, the earth l
A drilling rig 2 is constructed above, and a well 3 is formed directly below the drilling rig 2 by drilling the earth 1. A drill pipe 4 extends from the M-rig 2 into the well 3, and a drill collar 6 is connected to the tip ζ of the drill pipe 4 via an insulating collar 5. A bit 7 for excavation is attached to the tip of the drill collar 6, and the ground 1 is excavated by the bit 7 by rotating the drill pipe 4. drill color 6
Inside is the geology near the excavation area.

It houses a transmitting device 8 that detects temperature, pressure, etc., converts it into an electrical signal, and transmits underground information in the form of a modulated signal. A transmission output terminal (not shown) of this transmitting device 8 is connected to a drill pipe 4 and a drill collar 6, which are connected with an insulating collar 5 in between. The drill pipe 4 and the drill collar 6 constitute a transmission dipole antenna to transmit modulated extremely long wavelength electromagnetic waves (hereinafter referred to as electromagnetic waves) to the ground. A receiving device R consisting of an electric field sensor 20, an amplifier 10, and a signal processing section 11 is installed on the ground to receive electric field components of electromagnetic waves transmitted from underground. The electric field sensor 20 consists of two rectangular flat plate electrodes 20a and 20b arranged in parallel with each other at appropriate intervals and arranged to be orthogonal to the lines of electric force of electromagnetic waves, and at a depth beyond the stray current flow area of the earth 1. It consists of a buried M pole 30 buried at the bottom of an underground hole 1a excavated. These two flat plate electrodes 20a, 20b are connected to the connecting wire 7! l+7!2
and is connected to the input terminal of the amplifier 10 by.

Further, one end of the connecting wire 13 is connected to the buried electrode 30, and the other end is led out to the ground through the underground hole 1a and connected to the connecting wires 1 and 2. The output signal of the amplifier 10 is sent to the signal processing section 11
has been entered.

Next, the operation of the receiving apparatus configured as described above will be explained.

The underground transmitter 8 transmits the geology and temperature of the underground during excavation.

Transmit underground information such as pressure to the ground using electromagnetic waves.

Then, the electric field component of the transmitted electromagnetic wave is transmitted to an electric field sensor 20.
is detected.

In this case, since the flat plate electrodes 20b of the two opposing flat plate electrodes 20a and 20b of the electric field sensor 2o installed on the ground are connected to the buried electrode 30 underground, the two-handed plate electrode 20
A large potential difference is generated between a and 20b, and the both-hand plate electrode 2
A large detection voltage is obtained between 0a and 20b.

When the buried electrode 30 is located at a depth where no stray current flows in the ground 1, the electric field between the flat plate electrode 20a and the buried electrode 30 is not affected by the electric field due to the stray current in the ground 1. will be detected. The electric field detected by this electric field sensor 20 changes in accordance with changes in electromagnetic waves.

The detection voltage detected by the electric field sensor 20 is amplified by the amplifier 10 and input to the signal processing section 11 . The signal processing unit 11 detects the input voltage signal, processes the detected signal, and obtains underground information.

In this way, by detecting the electric field component of electromagnetic waves transmitted from underground using an electric field sensor, electromagnetic waves can be received without using a large-scale antenna. In particular, the detection voltage level can be increased by detecting an electric field between the ground plate electrode 20a, which has a large potential difference, and the underground electrode 30. On the other hand, if the buried electrode 30 is located at a depth underground where no stray current flows,
Noise level is reduced because it is not affected by stray current. Therefore, the increase in the detection voltage level and the reduction in the noise level act synergistically to significantly improve the S/N ratio.

FIG. 2 is a block diagram showing another embodiment of the receiving apparatus R of the present invention. In FIG. 2, the electric field sensor 20 consists of one flat plate electrode 20a installed on the ground and a buried electrode 30 buried underground. And the flat electrode 20a is a connection line! ! 1, the buried electrode 30 is connected to the input terminal of the amplifier 10 by a connecting line 13, and the amplification 'J:! The output signal of 10 is input to the signal processing section 11.

Therefore, like the receiver R shown in FIG. 1 described above, this receiver R also receives signals with high sensitivity to electromagnetic waves from underground and has a good signal-to-noise ratio. Further, since this electric field sensor 20 has a flat plate electrode 20a, the equipment cost is reduced.

In this embodiment, the buried electrode 30 was buried in the bottom of the underground hole 1a, but an M rod is also available in which an electrode is provided at the tip of an insulating column and a lead wire connected to the electrode is led out inside the insulating column. You can drive your body deep into the earthwork.

Alternatively, the outer surface of the insulating column constituting the electrode body constructed in this way may be covered with an electric MI shielding material. When the electromagnetic shielding material is arranged in this way, the influence of underground electric fields can be avoided.

〔effect〕

As described in detail above, according to the present invention, extremely long wavelength electromagnetic waves can be received without installing a large-scale antenna as in the prior art. In particular, the extremely long wavelength electromagnetic waves transmitted from underground are detected by detecting the electric field between the flat plate electrode on the ground and the buried electrode, where a large potential difference can be obtained, so the receiving sensitivity is high (and a highly sensitive receiving device is required). Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a receiving device for extremely long wavelength electromagnetic waves according to the present invention;
FIG. 2 is a block diagram showing another embodiment of the receiving apparatus, and FIG. 3 is a block diagram of a conventional extremely long wavelength electromagnetic wave receiving apparatus. 1... Earth 2... Drilling rig 8... Transmission device 2
0a, 20b... Flat electrode 30... Buried electrode R
...Receiving device In the figures, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa No. 112] 2 Kuchirotozoro2rho Figure 83 Procedural Amendment (Voluntary)

Claims (1)

[Scope of Claims] 1. A receiving device for extremely long wavelength electromagnetic waves that transmits information from underground to above ground, which includes a flat plate electrode provided on the ground to detect the electric field component of the extremely long wavelength electromagnetic waves, and a plate electrode provided underground. 1. A receiving device for ultra-long wavelength electromagnetic waves, characterized in that said information is obtained from an electric field detected by said electrodes. 2. In a receiving device for extremely long wavelength electromagnetic waves that transmits information from underground to the ground, two flat electrodes are installed on the ground facing each other to detect the electric field component of the extremely long wavelength electromagnetic waves, and one is installed underground. 1. A receiving device for extremely long wavelength electromagnetic waves, characterized in that the device includes a buried electrode connected to one of the flat plate electrodes, and is configured to obtain the information from an electric field generated between both the flat plate electrodes.