JPH06261008A - Signal transmission system - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a signal transmission system capable of high-speed signal transmission in a drilling well or a production well without affecting the mud circulation system or depending on the mud. [Structure] The drive circuit 23 of the transmitter 2A generates a voltage between the electrodes 21 and 22 according to a transmission signal. The signal current flowing from the electrode 21 to the drill string 1 causes a potential difference between the upper electrode 32 and the lower electrode 33 in the receiver 3A. The amplifier circuit 34 amplifies the potential difference and extracts it as a signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission system used for controlling a drilling equipment by sending a signal from the ground during excavation for obtaining underground resources such as oil and natural gas.

[0002]

2. Description of the Related Art Conventionally, as a signal transmission method for controlling underground drilling equipment at the time of drilling a well such as oil, it is circulated between a drill string (a metal pipe for drilling) in the well and the ground. There was a so-called mud pulse system in which signals were transmitted from the ground by pressure waves using mud as a medium. In addition, there was a magnetic field system in which a control signal for opening and closing a valve at the bottom of a mine was transmitted by a coil on the ground and a magnetic field sensor in the underground in a production well.

FIG. 10 is a block diagram showing a conventional mud pulse system signal transmission system. In the figure, 1 is a drill string which is a metal pipe for drilling, 51 is a mud flowing in the drill string 1, 52 is a stand pipe for sending the mud 51 into the drill string 1,
53 is a bypass pipe that bypasses the mud flow to create a pressure wave, 54 is a transmitter that sends the pressure wave to the mud, 56
Is a piezoelectric transducer that receives pressure waves at the bottom of the pit. Further, the transmitter 54 includes a valve 55 for opening and closing the flow path to the bypass pipe 53.

Next, the operation of what is shown in FIG. 10 will be described. First, the signal to be transmitted to the bottom of the pit is supplied to the transmitter 54. Then, the transmitter 54 has the valve 5 inside.
Open and close 5 according to the signal. As a result, a part of the mud 51 sent from the stand pipe 52 is partially bypassed by the bypass pipe 5.
As it flows into and out of No. 3, the pressure of the mud 51 sent to the bottom of the pit fluctuates. That is, a pressure wave corresponding to the signal is generated.

For example, if the signal supplied to the transmitter 54 is a digital signal as shown in FIG. 11 (a), the valve 55 is opened / closed in response to the signal, so that the signal from the transmitter 54 is transmitted as shown in FIG. 11 (b). The pressure wave indicated by is output to the mud 51. At the bottom of the pit, the piezoelectric transducer 56 receives the pressure wave and converts it into an electrical signal. In this way, the signal is transmitted from the transmitter 54 to the bottom of the pit.

FIG. 12 shows, for example, US Pat. No. 4,617,9.
It is a block diagram which shows the signal transmission system by the magnetic field method shown by No. 60. In FIG. 12, 61 is a transmission coil that generates a magnetic field, 62 is a drive circuit that drives the transmission coil 61, and 63 is a magnetic field sensor installed at the bottom of the pit.

In the structure shown in FIG. 12, first, a signal to be transmitted to the downhole is supplied to the drive circuit 62. Then, the drive circuit 62 causes a current to flow through the transmission coil 61 according to the signal. As a result, the transmission coil 61 generates a magnetic field according to the signal. At the bottom of the pit, the magnetic field sensor 63 receives a signal by detecting the magnetic field generated by the transmission coil 61. In this way, the signal is transmitted from the drive circuit 62 to the pit bottom.

[0008]

Since the conventional signal transmission system is constructed as described above, in the case of the mud pulse system, since the pressure wave is used as the transmission signal, the transmission speed is low, and , Mud circulatory system transmitter 5
4 and the bypass pipe 53 must be installed, and equipment changes are required. Furthermore, Mad 5 that circulates
Since 1 is essential, there is a problem that it cannot be used when the circulation of the mud 51 is stopped, or when an air drilling method of circulating compressed air is adopted.

On the other hand, the magnetic field method has a problem that the magnetic field generated by the transmission coil 61 in the magnetic field sensor 63 is weak. That is, even if the drill string 1 made of steel is present, its magnetic permeability is at most 1 to 2 orders of magnitude higher than the magnetic permeability of the surrounding stratum, and the drill string 1 cannot serve the role of transmitting a magnetic field. The magnetic field from the ground spreads spatially in the ground, and the magnetic field at the bottom of the pit significantly attenuates. As described above, the magnetic field method has a higher transmission speed than the mud pulse method and does not affect the circulation system of the mud 51, but in the excavation environment where vibration or electrical noise is received, the magnetic field is generated by the magnetic sensor 63. In some cases, it could not be detected, and there was a problem that it could be applied only to production wells in a static environment.

The present invention has been made in order to solve the above problems and enables high-speed signal transmission, and does not affect the mud circulation system or depend on the mud during excavation. It is also an object of the present invention to obtain a signal transmission system capable of sufficiently transmitting signals.

[0011]

A signal transmission system according to the present invention includes a signal transmission line formed of a conductor such as a drill string provided in a conductive medium such as a formation, and a signal transmission line using a transmission signal as a signal current. Between a transmitter having a signal sending unit such as an electrode and a toroidal coil for sending to the device, and a driving unit supplying a driving current for driving the signal sending unit, and an insulator for detecting the signal current sent through the signal transmission path. And a receiver having a signal detection unit such as a plurality of electrodes and a toroidal coil through which a signal is detected, and an amplification unit that amplifies the detected signal current and extracts a signal.

[0012]

The receiver according to the present invention detects the signal current transmitted through the signal transmission path and recognizes the signal transmitted by the transmitter from the signal current.

[0013]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a signal transmission system according to a first embodiment of the present invention. FIG. 1 shows a case where the signal transmission system is applied to an oil well drilling device.

In FIG. 1, 1 is a drill string which is a metal pipe for excavation, 2A is a transmitter for transmitting a signal,
3A is a receiver located at the bottom of the pit for receiving signals. In the transmitter 2A, 21 is an electrode connected to the drill string 1, 22 is an electrode buried in the ground, and 23 is an electrode 2
This is a drive circuit (drive unit) that generates a voltage between the first and second electrodes 22, and in this case, the two electrodes 21 and 22 form a signal transmission unit.

Further, in the receiver 3A, 31 is a cylindrical insulator fitted in a part of the drill string 1, and the drill string 1 is
It is electrically separated into an upper part and a lower part. 32 is an upper electrode connected to the upper portion of the drill string 1, 33 is a lower electrode connected to the lower portion of the drill string 1, 34 is an amplifier circuit (amplifier unit) for amplifying the potential difference between the upper electrode 32 and the lower electrode 33. ).

Next, the operation will be described. First, a signal to be transmitted to the bottom of the pit is supplied to the drive circuit 23. Then,
The drive circuit 23 generates a voltage according to a signal between the electrodes 21 and 23. Then, the drill string 1 and the electrode 21
A signal current flows from. Signal current is drill string 1
Although it leaks into the ground while flowing, the conductivity of the drill string 1 is higher than the conductivity of the formation by five digits or more, so the amount of leakage is small. Therefore, unlike the magnetic field method, the drill string 1 plays a role of sufficiently transmitting the signal current, and the signal attenuation in the receiver 3A is smaller than that in the magnetic field method.

Since there is an insulator 31 at the bottom of the pit, the signal current flowing through the drill string 1 once flows out to the surrounding strata at that point. Then, a part of the flowed out reaches the lower part of the drill string 1. As mentioned above, the conductivity of the formation is much smaller than that of the drill string 1, so that the upper electrode 32 on top of the drill string 1 is
And a potential difference is generated between the lower electrode 33 and the lower electrode 33 located below.

The amplifier circuit 34 detects the potential difference and amplifies and outputs it. Since the signal current depends on the transmission signal, the potential difference also depends on the transmission signal. Therefore, the output of the amplifier circuit 34 corresponds to the transmission signal.

Example 2. FIG. 2 is a block diagram showing a receiver 3B in the signal transmission system according to the second embodiment of the present invention. In this case, the insulator 311 is wound around the drill string 1, and a conductor having a width narrower than the width of the insulator 311 is wound around the insulator 311 and the lower electrode 331 is provided on the conductor. Even in such a configuration, since the upper electrode 32 and the lower electrode 331 are separated by the insulator 311, the upper electrode 32 is separated by the signal current.
And a lower electrode 331 generates a potential difference.

Example 3. FIG. 3 is a block diagram showing a receiver 3C in a signal transmission system according to a third embodiment of the present invention. In this case, the insulator 312 is wound around the drill string 1, and the isolated lower electrode 332 is provided on the surface of the insulator 312. Even in such a configuration, since the upper electrode 32 and the lower electrode 332 are separated by the insulator 312, a potential difference is generated between the upper electrode 32 and the lower electrode 332 due to the signal current. In addition, a plurality of such isolated lower electrodes 332 may be provided on the surface of the insulator 312.

Example 4. FIG. 4 is a block diagram showing a transmitter 2B in a signal transmission system according to a fourth embodiment of the present invention. In the above embodiment, the electrode 22 is directly buried in the ground, but in this case, the electrode 24 covered with an insulator is buried. In addition, the drive circuit 23
The wiring from the electrode 24 to the electrode 24 is also covered with an insulator in the ground. By doing so, the output impedance of the transmitter 2B can be made large, so that the transmission efficiency is improved. That is, the transmission power can be reduced.

Embodiment 5. FIG. 5 is a block diagram showing a transmitter 2C in a signal transmission system according to a fifth embodiment of the present invention. In this case, the insulator 25 is directly provided around part or all of the drill string 1. Even in this case, the same effect as that of the transmitter 2B shown in FIG. 4 can be obtained.

Example 6. FIG. 6 is a block diagram showing a transmitter 2D in a signal transmission system according to a sixth embodiment of the present invention. As shown in FIG. 6, a casing pipe 4 provided outside the drill string 1 to protect the mine wall.
In the case where the casing pipe 4 is provided, the insulator 26 is provided around part or all of the casing pipe 4. Even in this case, the same effect as the effect obtained by the transmitter 2B shown in FIG. 4 and the transmitter 2C shown in FIG. 5 can be obtained. The same effect can be obtained even if the insulator 26 is provided inside the casing pipe 4 instead of outside.

Example 7. In each of the above embodiments, the transmitters 2A, 2B, 2C, 2D having a plurality of electrodes and the receivers 3A, 3B, 3C are shown, but the transmitter and the receiver having a toroidal coil are provided. Good.

FIG. 7 is a block diagram showing a signal transmission system according to a seventh embodiment of the present invention including such a transmitter 2E and a receiver 3D. In the figure, 28 is a transmission coil made of a toroidal coil, and 38 is a reception coil made of a toroidal coil.

In this case, when a signal to be transmitted to the pit bottom is supplied to the drive circuit 23, a signal current corresponding to the signal flows through the transmission coil 28. The signal current propagates through the drill string 1, and the signal current flows through the receiving coil 38 at the bottom of the pit. The amplifier circuit 34 amplifies and outputs the signal current.

Example 8. In each of the above embodiments, a system including transmitters 2A, 2B, 2C, 2D having a plurality of electrodes and receivers 3A, 3B, 3C having a plurality of electrodes, or a transmitter 2E having a toroidal coil and a toroidal coil are provided. Although the system including the receiver 3D is shown, the one having a plurality of electrodes and the one having a toroidal coil may be combined.

FIG. 8 is a block diagram showing a signal transmission system including a transmitter 2A having a plurality of electrodes and a receiver 3D having a toroidal coil. Even in this case, the signal can be transmitted from the ground to the bottom of the pit.

Example 9. Further, as shown in FIG. 9, a signal transmission system including a transmitter 2E having a toroidal coil and a receiver 3A having a plurality of electrodes may be used. Even in this case, the signal can be transmitted from the ground to the bottom of the pit.

Not only the system shown in FIG. 8 or 9, but also the transmitters 2A, 2B, 2 shown in FIGS.
A system in which C, 2D, 2E and each of the receivers 3A, 3B, 3C, 3D are arbitrarily combined can be used.

In each of the above embodiments, the case where the drill string 1 is used as a signal transmission line has been described, but if there is a conductor such as a casing pipe from the ground to the bottom of the hole, it is used as a signal transmission line. be able to.

In each of the above-mentioned embodiments, the signal transmission at the time of excavating the oil well has been described, but the present invention is applied to the signal transmission in the production well such as the signal transmission for the underground valve control during the production of oil or the like. You can also Further, the present invention can be similarly applied to not only excavation and production of oil but also other cases where a conductor extending from the ground to the ground exists. Furthermore, if a conductor serving as a signal transmission path exists, it can be applied to signal transmission from the ground or the sea to the sea or the ground in the ocean.

[0033]

As described above, according to the present invention, the signal transmission system is provided with the signal transmission path provided in the conductive medium such as the ground, and the signal current output from the transmitter is received by the receiver. Since there is no need to influence the mud circulatory system or to depend on the mud, the signal attenuation is small, and there is an effect that it can be sufficiently used even during excavation.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a signal transmission system according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a receiver in a signal transmission system according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a receiver in a signal transmission system according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a transmitter in a signal transmission system according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram showing a transmitter in a signal transmission system according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a transmitter in a signal transmission system according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram showing a signal transmission system according to a seventh embodiment of the present invention.

FIG. 8 is a configuration diagram showing a signal transmission system according to an eighth embodiment of the present invention.

FIG. 9 is a configuration diagram showing a signal transmission system according to a ninth embodiment of the present invention.

FIG. 10 is a configuration diagram showing a conventional signal transmission system.

FIG. 11 is a waveform diagram showing a signal waveform in that shown in FIG.

FIG. 12 is a configuration diagram showing another conventional signal transmission system.

[Explanation of symbols]

 1 Drill String (Signal Transmission Line) 2A, 2B, 2C, 2D, 2E Transmitter 21 Electrode (Signal Transmission Unit) 22 Electrode (Signal Transmission Unit) 23 Drive Circuit (Drive Unit) 3A, 3B, 3C, 3D Receiver 32 Upper electrode (signal detector) 33 Lower electrode (signal detector) 34 Amplifier circuit (amplifier)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Minoru 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Industrial Systems Research Center

Claims (1)

[Claims] 1. In a signal transmission system for transmitting a signal from the ground or the sea to the ground or the sea, a signal transmission line made of a conductor provided in a conductive medium, and the transmission signal as a signal current to the signal transmission line. A transmitter having a signal sending section for sending out, and a driving section for supplying a driving current for driving the signal sending section, a signal detecting section for detecting a signal current transmitted through the signal transmission path, and detection by the signal detecting section And a receiver having an amplifier for amplifying the signal current and extracting the signal current as a signal.