CN112333122A - Ground and underground synchronization system and synchronization method for inter-well electromagnetic imaging system - Google Patents
Ground and underground synchronization system and synchronization method for inter-well electromagnetic imaging system Download PDFInfo
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- CN112333122A CN112333122A CN202011213039.3A CN202011213039A CN112333122A CN 112333122 A CN112333122 A CN 112333122A CN 202011213039 A CN202011213039 A CN 202011213039A CN 112333122 A CN112333122 A CN 112333122A
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- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000003384 imaging method Methods 0.000 title claims abstract description 15
- 238000011084 recovery Methods 0.000 claims abstract description 21
- 239000013078 crystal Substances 0.000 claims description 13
- 230000001360 synchronised effect Effects 0.000 abstract description 10
- 230000005540 biological transmission Effects 0.000 abstract description 7
- 230000008054 signal transmission Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/08—Modifications for reducing interference; Modifications for reducing effects due to line faults ; Receiver end arrangements for detecting or overcoming line faults
- H04L25/085—Arrangements for reducing interference in line transmission systems, e.g. by differential transmission
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/16—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop
- H03L7/18—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop using a frequency divider or counter in the loop
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
- H04L25/40—Transmitting circuits; Receiving circuits
- H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
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- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
The invention discloses a ground and underground synchronization system and a synchronization method of an interwell electromagnetic imaging system, wherein the system comprises a ground sending circuit on the ground and an underground recovery circuit in the underground, wherein the ground sending circuit comprises a signal source, a driving circuit electrically connected with the signal source, a single-end to differential circuit electrically connected with the driving circuit and a transformer T1 electrically connected with the single-end to differential circuit; the downhole recovery circuit includes a transformer T2; the transformer T1 and the transformer T2 are electrically connected by a cable. According to the synchronous system disclosed by the invention, the signal is driven and amplified by the driving circuit of the ground transmitting circuit, then differential signal transmission is used, and then the signals are isolated by the transformer, so that the signal transmission distance is increased, and the interference of the signals in the transmission process on a cable of several kilometers is reduced.
Description
Technical Field
The invention belongs to the field of petroleum logging, and particularly relates to a ground and underground synchronization system and a synchronization method for an interwell electromagnetic imaging system in the field.
Background
In the field of oil logging applications, some instruments need to meet the phase synchronization of surface and downhole signals. For example, in the synchronous implementation of the ground and the downhole systems of the inter-well electromagnetic imaging system, the ground circuit and the downhole circuit are required to implement real-time synchronization. The existing method utilizes the characteristics of balanced transmission and differential receiving of an RS-485 bus to transmit a synchronous signal on the ground to the underground through a cable of several kilometers. The signal transmission mode can inhibit common mode interference and meet the requirement of kilometer long-distance signal transmission. However, it should be noted that, because the logging cable has 7 cable cores, 2 cable cores are occupied by sending a clock-synchronized reference signal from the surface to the downhole, and other cable cores are used for power supply and communication of downhole instruments. Particularly, at a transmitting end, when underground transmission is carried out, the power supply current is large, the synchronous signals transmitted by the cable line are seriously interfered, so that the transmitted synchronous signals generate burrs and jitter, the analog phase-locked loop cannot be normally locked, and even the ground and the underground recovery signals cannot be synchronized. Therefore, a synchronization method with strong interference resistance must be found to complete the real-time synchronization of the surface and the downhole circuit.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a ground and underground synchronization system and a synchronization method of an interwell electromagnetic imaging system, which can obtain stable synchronization signals underground.
The invention adopts the following technical scheme:
in an interwell electromagnetic imaging system surface and downhole synchronization system, the improvement comprising: the underground recovery circuit comprises a ground sending circuit on the ground and an underground recovery circuit in a well, wherein the ground sending circuit comprises a signal source, a driving circuit electrically connected with the signal source, a single-ended to differential circuit electrically connected with the driving circuit, and a transformer T1 electrically connected with the single-ended to differential circuit; the underground recovery circuit comprises a transformer T2, a low-pass filter electrically connected with the transformer T2, a differential-to-single-ended circuit electrically connected with the low-pass filter, a comparator electrically connected with the differential-to-single-ended circuit, and an all-digital phase-locked loop circuit electrically connected with the comparator; the transformer T1 and the transformer T2 are electrically connected by a cable.
Furthermore, the underground recovery circuit also comprises a crystal oscillator and an N frequency division circuit which are electrically connected with the all-digital phase-locked loop circuit.
Further, the crystal oscillator adopts a voltage-controlled crystal oscillator.
Further, the cable length is about 5000 meters.
In a method of synchronizing the surface of an interwell electromagnetic imaging system with a downhole synchronization system, the improvement comprising: the signal source of the ground transmitting circuit transmits a sinusoidal signal f to the driving circuitinThe sinusoidal signal is amplified by the driving circuit, converted into differential signal by the single-end to differential circuit, and finally transmitted to the transformer T2 of the underground recovery circuit through the transformer T1 and the cable, the transformer T2 inputs the signal into the low-pass filter, the low-pass filter filters out the interference signal superposed on the signal and sends the signal into the differential to single-end circuit, the differential to single-end circuit converts the signal into single-end signal and sends the signal into the comparator, the comparator converts the signal from sinusoidal signal into square wave signal fin1Post-input ADPLL circuit driven from square wave signal fin1In-process recovery of synchronization signal foutAnd output.
Further, the signal source sends a sinusoidal signal f with a frequency of 109Hz to the drive circuitin。
The invention has the beneficial effects that:
according to the synchronous system disclosed by the invention, the signal is driven and amplified by the driving circuit of the ground transmitting circuit, then differential signal transmission is used, and then the signals are isolated by the transformer, so that the signal transmission distance is increased, and the interference of the signals in the transmission process on a cable of several kilometers is reduced. Signals received by the underground recovery circuit are sequentially isolated by the transformer, filtered by the band-pass filter and converted into single-ended signals by the magnetic isolation differential-to-single-ended circuit, so that the electromagnetic interference of other cable lines on the synchronous signals is reduced, and the stability of transmitting the synchronous signals is improved.
By using the all-digital phase-locked loop circuit, even if burrs are increased and jitter is increased due to strong current interference of signals received underground, the input signals can still be locked, stable signals with the same frequency and phase as the input signals are recovered, the anti-interference capability of the signals is enhanced, and the ground and underground synchronization is achieved.
The synchronization method disclosed by the invention reduces the interference of electromagnetic signals to the synchronization signals, improves the long-distance transmission quality of the differential signals, can obtain more stable synchronization signals underground, and achieves the real-time synchronization of ground and underground received signals.
Drawings
Fig. 1 is a block diagram of a synchronization system disclosed in embodiment 1 of the present invention;
FIG. 2 is a synchronization state diagram of the ADPLL circuit at a cable current of 200 mA;
figure 3 is a synchronization state diagram of the adpll circuit at a cable current of 500 mA.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Embodiment 1, as shown in fig. 1, this embodiment discloses a surface and downhole synchronization system for an interwell electromagnetic imaging system, which includes a surface transmitting circuit (dashed box N1) on the surface and a downhole recovery circuit (dashed box N2) in the downhole, where the surface transmitting circuit includes a signal source, a driving circuit electrically connected to the signal source, a single-ended to differential circuit electrically connected to the driving circuit, and a transformer T1 electrically connected to the single-ended to differential circuit; the underground recovery circuit comprises a transformer T2, a low-pass filter electrically connected with the transformer T2, a differential-to-single-ended circuit electrically connected with the low-pass filter, a comparator electrically connected with the differential-to-single-ended circuit, and an all-digital phase-locked loop circuit electrically connected with the comparator; the transformer T1 and the transformer T2 are electrically connected by a cable having a length of about 5000 meters.
In this embodiment, the downhole recovery circuit further comprises a crystal oscillator and a divide-by-N circuit electrically connected to the adpll circuit. The crystal oscillator adopts a voltage-controlled crystal oscillator, and the frequency of the crystal oscillator can drift along with the voltage-controlled crystal oscillator when the underground temperature rises, so that the self-adaptive temperature compensation system based on the DSP is adopted to correct the frequency of the crystal oscillator in real time, and the precision of the output frequency of the crystal oscillator is ensured.
The embodiment also discloses a synchronization method, the ground and underground synchronization system of the interwell electromagnetic imaging system is used, and a signal source of the ground sending circuit sends a sinusoidal single-ended signal f to the driving circuitinThe sinusoidal signal is amplified by the drive circuit, converted into differential signal by the single-end to differential circuit, isolated by the transformer T1 and transmitted to the transformer T2 of the underground recovery circuit by the cable, the transformer T2 isolates the signal and inputs the signal into the low-pass filter, the low-pass filter filters out the interference signal superposed on the signal and sends the signal into the differential to single-end circuit, the differential to single-end circuit converts the signal into single-end signal and sends the signal into the comparator, the comparator converts the signal from sinusoidal signal into square wave signal fin1Post-input ADPLL circuit driven from square wave signal fin1In-process recovery of synchronization signal foutAnd output. And completing real-time synchronization of the ground and the underground. The synchronous signal recovered from the underground is the same frequency as the signal at the input end, and the phase difference is 90 degrees.
The signal source of the embodiment sends a sinusoidal signal f with the frequency of 109Hz to the driving circuitinSince a high-frequency signal is not suitable for long-distance transmission, a low-frequency signal is used as a synchronization signal.
The all-digital phase-locked loop circuit has the characteristics of strong anti-jamming capability and high locking speed. The real-time synchronization between the ground and the underground is completed by using the all-digital phase-locked loop circuit to replace an analog phase-locked loop.
As can be seen from fig. 2 and 3, the larger the cable supply current is, the more the synchronization signal glitches are and the larger the jitter is after the transmission of the long cable. However, even if the signal glitch is increased and the jitter is obvious, the adpll circuit can still complete the frequency and phase locking to achieve the signal synchronization, thereby verifying the correctness of the synchronization method of the embodiment.
Claims (6)
1. The utility model provides an interwell electromagnetic imaging system ground and downhole synchronization system which characterized in that: the underground recovery circuit comprises a ground sending circuit on the ground and an underground recovery circuit in a well, wherein the ground sending circuit comprises a signal source, a driving circuit electrically connected with the signal source, a single-ended to differential circuit electrically connected with the driving circuit, and a transformer T1 electrically connected with the single-ended to differential circuit; the underground recovery circuit comprises a transformer T2, a low-pass filter electrically connected with the transformer T2, a differential-to-single-ended circuit electrically connected with the low-pass filter, a comparator electrically connected with the differential-to-single-ended circuit, and an all-digital phase-locked loop circuit electrically connected with the comparator; the transformer T1 and the transformer T2 are electrically connected by a cable.
2. An interwell electromagnetic imaging system surface and downhole synchronization system as defined in claim 1, wherein: the underground recovery circuit also comprises a crystal oscillator and an N frequency division circuit which are electrically connected with the all-digital phase-locked loop circuit.
3. An interwell electromagnetic imaging system surface and downhole synchronization system as claimed in claim 2, wherein: the crystal oscillator adopts a voltage-controlled crystal oscillator.
4. An interwell electromagnetic imaging system surface and downhole synchronization system as defined in claim 1, wherein: the cable length is about 5000 meters.
5. A synchronization method for surface and downhole synchronization of an electromagnetic imaging system between wells as defined in claim 1, wherein: the signal source of the ground transmitting circuit transmits a sinusoidal signal f to the driving circuitinThe sinusoidal signal is amplified by the driving circuit, converted into differential signal by the single-end to differential circuit, and finally transmitted to the transformer T2 of the underground recovery circuit through the transformer T1 and the cable, the transformer T2 inputs the signal into the low-pass filter, the low-pass filter filters out the interference signal superposed on the signal and sends the signal into the differential to single-end circuit, the differential to single-end circuit converts the signal into single-end signal and sends the signal into the comparator, the comparator converts the signal from sinusoidal signal into square wave signal fin1Post-input ADPLL circuit driven from square wave signal fin1In-process recovery of synchronization signal foutAnd output.
6. The synchronization method according to claim 5, characterized in that: the signal source sends a sinusoidal signal f with the frequency of 109Hz to the drive circuitin。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011213039.3A CN112333122A (en) | 2020-11-03 | 2020-11-03 | Ground and underground synchronization system and synchronization method for inter-well electromagnetic imaging system |
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| CN202011213039.3A CN112333122A (en) | 2020-11-03 | 2020-11-03 | Ground and underground synchronization system and synchronization method for inter-well electromagnetic imaging system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113358937A (en) * | 2021-04-26 | 2021-09-07 | 广西电网有限责任公司电力科学研究院 | Signal synchronous sampling device in capacitor cable-free measurement |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106499389A (en) * | 2016-10-31 | 2017-03-15 | 华中科技大学 | Electromagnetic tool send-receive clock synchronization system and method between a kind of well |
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- 2020-11-03 CN CN202011213039.3A patent/CN112333122A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106499389A (en) * | 2016-10-31 | 2017-03-15 | 华中科技大学 | Electromagnetic tool send-receive clock synchronization system and method between a kind of well |
Non-Patent Citations (2)
| Title |
|---|
| 周凯波;莫德欠;陈寰;刘颉;曹攀辉;: "井间电磁成像测井仪收发同步技术研究", 测井技术, no. 05 * |
| 臧德福;张庆乐;晁永胜;杨爱锋;李智强;: "井间电磁成像***发射和接收同步测量应用研究", 地球物理学进展, no. 04, pages 0 - 5 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113358937A (en) * | 2021-04-26 | 2021-09-07 | 广西电网有限责任公司电力科学研究院 | Signal synchronous sampling device in capacitor cable-free measurement |
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