JPS6376655A - Communication method for data from underground - Google Patents

Abstract

PURPOSE:To surely detect the synchronization of an electromagnetic wave whose phase is modulated and to improve the reliability of communications by transmitting a sine wave with a fixed frequency to a receiver from a transmitter prior to data transmission and acquiring the synchronization of a data transmission wave based on the frequency of the received sine wave. CONSTITUTION:Prior to data transmission, the sine wave with a fixed frequency is transmitted to the underground receiver 20 from the transmitter 90 in a pit. Receiving the wave, the receiver 20 acquries the synchronization of the data transmission wave based on the frequency of the received sine wave. Namely, the underground transmitter 90 first transmits the sine wave with a fixed frequency. The receiver 20, receiving that, stores information about the frequency. Then the transmitter 90 receives the data transmission wave. When receiving that, the receiver 20 detects the synchronization of the data transmission wave with the aid of the frequency of the having been received sine wave. Thus a reference for detection waves becomes precise. Therefore the detection is made more precisely, and the reliability of reception data is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, a measuring device for well logging, that is, a vertical shaft for mining oil or natural gas, that is, when drilling an oil well, a gas well, etc. The present invention relates to a communication method for transmitting data obtained from a device attached to the tip of a drill pipe to measure properties of the bottom of a pit, or various other measuring devices buried underground.

[Prior art]

For example, conventionally, when drilling a vertical shaft such as an oil well for oil drilling, in order to obtain various information about the geology near the bottom of the hole or the drilling bit used for drilling 1, the drill pipe was first raised above ground and inspected, or Measurements can be taken by lowering a layer measuring device into the shaft, or mant logging (which analyzes the state and components of the mud that circulates upward in the shaft from the top of the drill pipe through the tip of the bit during drilling). A method called mud logging (muddy water logging) has been adopted.

However, each of the above-mentioned methods requires a relatively long time to measure;
Furthermore, it was difficult to measure the bottom of the hole in real time during excavation. Due to these circumstances, in recent years MWD
(Measurement While Drill)
A method called g> has been developed. Simply put, this MWD is achieved by attaching a logging measurement device equipped with a sensor to the tip of a drill pipe near the bottom, and transmitting the various data obtained to the ground using electromagnetic waves as a medium. The purpose is to measure the properties of the bottom of the mine (including the focus state) in real time and obtain that data.

Figure 4 shows, as an example, OGJ Report Feb.
21. In 1983 “5econd-Generation”
n MWD Tool Pa5ses FieldTe
In the schematic diagram showing the configuration of the equipment announced under the title "S T", I is a drilling rig, 2 is a stratum, 3 is a vertical shaft being excavated, that is, an oil well, and 4 is a machine that is rotated by a power source (not shown). This is a drill pipe for transmitting the force to the bit 5, and a drill string is constructed by connecting a large number of them at their respective connecting parts depending on the drilling depth.

5 is a bit for drilling the stratum as described above, and 6 is an insulating collar that divides the most advanced drill pipe 40 directly above the bit 5 into a bottom portion 4I and an upper portion 42 and electrically insulates the two. It is.

Furthermore, in FIG. 4, an area 7 surrounded by a broken line indicates a dipole antenna formed by the bottom 41 and the top 42 of the most advanced drill pipe 40, and the drill pipe 4 and the insulating collar 6 at a position higher than that. There is. , and 8
is a containment vessel attached to the bottom 41 of the most advanced drill pipe 40. This containment vessel 8 houses a well logging measurement device 80 and a transmitter 90 of a communication device for communicating data obtained by this well logging measurement device 80.

The well logging measurement device 80 measures various properties, such as temperature, regarding the bottom of the oil well 3 and the bit 5 during drilling.

It consists of sensors that measure pressure, vibration, three rotation torque, etc. The transmitter 90 of the communication device is an oscillator or the like that modulates and amplifies the data obtained by the well logging measurement device 80 and outputs it as an electromagnetic wave as shown by the dotted line from the above-mentioned dipole antenna 7. It is configured.

On the other hand, on the ground is an antenna 1 that constitutes a receiving section of a communication device.
0. Receiver amplifier 11. A signal processing section 12 and the like are provided. Specifically, a linear antenna 10 is extended approximately centered on the oil well 3, and electromagnetic waves received by this antenna 10 are output to an amplifier 11. This amplifier II amplifies the signal given from the antenna 10 and outputs it to the signal processing section 12. The signal processing section 12 includes an amplifier 11
The output signal is detected and the data at the bottom of the pit, that is, the data measured by the well logging measuring device 80 housed in the containment vessel 8 is reproduced.

FIG. 5 is an enlarged vertical cross-sectional view of the above-mentioned dipole antenna 7, in which the insulating collar 6 of the most advanced drill pipe 40 is connected to the transmitter 90 housed in the containment vessel 8.
A conductive wire CL C2 is connected to the bottom part 41 and the top part 42 which are electrically insulated by the dipole antenna 7.
is configured.

Such conventional devices operate as follows.

When the drilling rig 1 rotates a drill string consisting of a large number of drill pipes 4, 4..., the bit 5 attached to the tip of the most advanced drill pipe 40 also rotates, and the rotation of the bit 5 causes the oil well to be drilled. Stratum 2 at the bottom of 3 is excavated. At this time, the logging measurement device 80 in the containment vessel 8 installed at the bottom 41 of the most advanced drill pipe 40 uses a sensor to measure the properties of the stratum 2 at the bottom of the well or the state of the bit 5, and obtains the results. The transmitted data is modulated and amplified by a transmitter 90, and applied as an AC signal of 5 to 60 Hz to a dipole antenna 7 whose cutting edge drill pipe 40 is electrically insulated by an insulating collar 6. As a result, electromagnetic waves are radiated from the dipole antenna 7 as shown by dotted lines in the figure.

Note that the frequency applied to the dipole antenna 7 is 60
In the case of 1 Iz, when converted to a wavelength in the air, it is an extremely long wavelength of 5000-.

On the ground, on the other hand, the electromagnetic waves radiated from the dipole antenna 7 and propagated through the stratum 2 are received by the linear antenna 10, amplified by the amplifier 11, and then sent to the signal processing unit 12.
The signal is detected and reproduced as data in the desired format.

(Problem to be solved by the invention) However, in the case of communication as described above, attenuation is large when propagating underground, and the S/N ratio is extremely low.For this reason, synchronous detection of phase-modulated electromagnetic waves is difficult. There was a problem in that the reliability of communication was extremely low.The present invention was made to solve this problem.Prior to data transmission, a sine wave of a constant frequency is transmitted, and the reception The purpose of this invention is to provide a communication method in which detection is performed reliably based on the frequency of this sine wave.

[Means for solving problems]

The data communication method according to the present invention transmits a sine wave of a constant frequency from a transmitter in a mine to a receiver on the ground prior to data transmission, and the receiver that receives this transmits a data transmission wave based on the frequency of the received sine wave. This synchronizes the detection.

(Operation) The underground transmitter first transmits a sine wave with a constant frequency. When the receiver receives this, it stores information about that frequency. Next, the transmitter transmits a data transmission wave. When the data transmission wave is received, the frequency of the previously transmitted sine wave is used to perform synchronous detection of the data transmission wave.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.

1 and 2 are block diagrams schematically illustrating the apparatus used to carry out the present invention, and show the configurations of a transmitter 90 of the apparatus of the present invention and a receiver of the apparatus of the present invention, respectively, shown together with the well logging measuring device 80. ing. Further, FIG. 3 is a signal waveform diagram for explaining the operation of the apparatus of the present invention.

In the figure, Sl, S2, .

The analog signals output by each bottom-hole sensor Sl, S2...Sn are given to a multiplexer 81, and the output of this multiplexer 81 is given to an A/D converter 82, where it is converted into a digital signal and sent to a microprocessor. 83.

A memory 84 is connected to the microprocessor 83, and the data detected by each bottom hole sensor Sl, 52...Sn is temporarily stored in the memory 84. Reference numeral 90 denotes a transmitter, and includes a control section 91 that receives signals output from the microprocessor 83 and controls transmission. A P/S conversion circuit 92 that converts data to be transmitted from parallel to serial, an oscillation circuit 93, and a modulation circuit 94 that phase modulates the output of the P/S conversion circuit 92 based on a sine wave of a constant frequency generated by the oscillation circuit 93.
The output of the modulation circuit 94 or the output of the oscillation circuit 93 is selectively output to the dipole antenna 7 described above.

FIG. 3(a) shows the output of the oscillation circuit 93, and when the microprocessor 83 periodically or irregularly issues a signal instructing the transmitter 90 to transmit, the control unit 91
drives the oscillation circuit 93 and outputs its output to the dipole antenna 7 for a predetermined period of time. Based on the above-mentioned transmission instruction signal, the microprocessor 83 transmits bit parallel data obtained from the bottom hole sensor 31 or the like or stored in the memory 84 to the control unit 91. The control unit 9I supplies this to the P/S conversion circuit 92, converts it into bit serial data, and outputs it to the modulation circuit 94, where it is phase modulated.

FIG. 3 (b) shows an example of the output of the P/S conversion circuit 92;
C) shows the modulation circuit 94 output.

In this embodiment, the duration of one bit of data output from the P/S conversion circuit 92 is set to 2 Hz of the output from the oscillation circuit 93. The phase modulation is performed so as to output a sine wave having the same phase and the opposite phase as the output of the oscillation circuit 93 in response to the binary signal "1", "1", and "0".

The electromagnetic waves transmitted from the dipole antenna 7 are received by the antenna IO on the ground and given to the receiver 20. The received wave from the receiver 20 is amplified by the amplifier 11 and then input to the switching circuit 22 via the bandpass filter 21 whose passband is a narrow band centered on the sine wave generated by the oscillation circuit 93. It goes without saying that noise is removed by the bandpass filter 21. Switching circuit 22
gives the memory 23 a signal wave received for a predetermined time after the start of reception, that is, a sine wave emitted by the oscillation circuit 93,
Store this sine wave in it. The switching circuit 22 supplies the subsequent received signal to the synchronous detection circuit 24. The synchronous detection circuit 24 reads out the sine wave stored therein from the memory 23, and synchronously detects the received signal based on this sine wave. As a result, a bit-serial digital signal as shown in FIG. 3(b) is obtained, and this signal is supplied to the signal processing section 12, where data analysis is performed.

In the above embodiment, the received sine wave is directly stored in the memory 23.
However, it is also possible to detect the frequency of the received sine wave, oscillate the same frequency within the receiver, and use this to perform synchronous detection.

Further, the present invention is applicable not only to communication of well logging data but also to communication from underground to above ground in general.

(Effects) In the case of the present invention as described above, since the reference for synchronous detection is made accurate, detection can be performed reliably and the reliability of received data is increased.Also, when communicating, a sine wave of a predetermined frequency is first transmitted, so this The present invention has excellent effects, such as being able to be worn as a signal to start transmission.

[Brief explanation of the drawing]

Figure 1.2 is a block diagram of a transmitter and receiver used to carry out the method of the present invention, Figure 3 is a number of signal waveforms for explaining its operation, and Figure 4.5 is an explanatory diagram of the prior art. It is. Sl, S2...Sn...Bottomhole sensor 4...Drill pipe 7...Dipole antenna IO...
Antenna 20...Receiver 23...Memory 2
4... Synchronous detection circuit 80... Measuring device for well logging 9
0...Transmitter 93...Oscillation circuit 94...
Modulation circuit Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a method of communicating from an underground transmitter to a receiver on the ground, prior to data transmission, a sine wave of a constant frequency is transmitted from the transmitter to the receiver, and the receiver receives the received sine wave. A data communication method characterized by synchronizing detection of data transmission waves based on frequency.