CN112350804B - Communication device and method for cased well extremely low frequency channel - Google Patents

Abstract

The present invention discloses a communication method and device for extremely low frequency channel of casing well. The communication device includes a downhole terminal and a surface terminal; the downhole terminal is configured to obtain an n-ary data group representing the data to be transmitted, where n is an integer greater than 1, and the n-ary data group is divided according to the array configuration rule to have the same number of digits At least two intermediate data groups are determined, and the current communication mode is judged. After judging that the communication mode is the communication rate optimization mode, all intermediate data groups are modulated as signals to be transmitted by superimposing modulation and demodulation rules, and the signals to be transmitted are sent along the casing well channel. to the ground terminal; the ground terminal is configured to demodulate the signal to be transmitted into an intermediate data group according to the superposition modulation and demodulation rule; obtain an n-ary data group representing the data to be transmitted according to the array configuration rule and all the intermediate data groups. The present invention can maintain the efficiency of signal transmission in cased hole channels with extremely low resistivity.

Description

Communication device and method for cased hole very low frequency channel

technical field

The invention relates to the field of petrochemical industry, in particular to a communication device and a device for extremely low frequency channel of cased wells.

Background technique

The intelligent development of the traditional oil and gas industry is the trend of the times. Under this background, the concept of "smart oilfield" came into being.

Informatization is the basis of intelligence, but domestic oil and gas exploitation operations are still limited by existing technologies, and real-time monitoring of downhole operation data cannot be achieved.

Therefore, the real-time monitoring of engineering parameters and geological parameter design of downhole operations is an important issue in oil and gas exploitation engineering.

At present, the more mainstream development trend is to replace the traditional wired cable transmission and develop long-distance wireless transmission technology. At present, the following problems still exist in long-distance wireless transmission:

The acoustic signal is greatly attenuated at the oil pipe joint, and at the same time, it is greatly affected by the noise of engineering operations, which seriously affects the signal transmission.

The environmental resistivity of the casing hole channel is extremely low, and the intensity of the electromagnetic wave signal is greatly attenuated.

Oil well communication requires a long distance, and long-distance electromagnetic wave communication carriers usually use low-frequency carriers, resulting in a small channel transmission bandwidth and a slow transmission rate.

New communication methods such as frequency hopping communication and OFDM used in communication reduce the communication rate while improving the signal-to-noise ratio. At the same time, the downhole space is small, the hardware volume is limited, and it is difficult to realize complex communication methods.

The oil well space is small and the environment is complex, and there are high requirements on technical indicators such as the hardware volume and temperature resistance of the communication device, which makes it difficult to realize new communication methods such as frequency hopping communication and OFDM.

SUMMARY OF THE INVENTION

The embodiment of the present invention discloses at least one communication device for an extremely low frequency channel of a cased well.

Specifically, the communication device includes at least one downhole terminal and one ground terminal;

The downhole terminal is configured to obtain an n-ary data group representing the data to be transmitted, where n is an integer greater than 1, and divide the n-ary data group into at least two intermediate data groups with the same number of digits according to an array configuration rule , judging that the current communication mode is the communication rate optimization mode or the communication quality optimization mode, after judging that the communication mode is the communication rate optimization mode, modulate all the intermediate data groups by a superposition modulation and demodulation rule as a signal to be transmitted, Send the signal to be transmitted to the ground terminal along the casing well channel; the ground terminal is configured to demodulate the signal to be transmitted according to the superposition modulation and demodulation rule to be the intermediate data group; according to the array The configuration rules and all the intermediate data groups acquire the n-ary data group representing the data to be transmitted.

Further, this embodiment discloses an oil and gas exploitation system. The oil and gas production system includes a casing and an oil pipe; the casing is drilled to connect the formation and the oil layer; the gap of the oil pipe is matched in the casing; the gap between the casing and the oil pipe is filled with bottom hole fluid, so The gap between the casing and the oil pipe and the bottom hole fluid constitute the cased well channel; the downhole terminal is immersed in the bottom hole fluid and installed on the oil pipe, and the surface terminal is deployed in the formation.

Further, this embodiment discloses a communication method. When the method is executed, the steps include: the downhole terminal acquires an n-ary data group representing the data to be transmitted, where n is an integer greater than 1; the downhole terminal divides the n-ary data group according to an array configuration rule to have the same number of digits at least two intermediate data sets; the downhole terminal determines that the current communication mode is the communication rate optimization mode or the communication quality optimization mode; after judging that the communication mode is the communication rate optimization mode, the downhole terminal modulates all the The intermediate data group is a signal to be transmitted; the downhole terminal sends the to-be-transmitted signal to the outside along a casing well channel; the surface terminal demodulates the to-be-transmitted signal according to the superposition modulation and demodulation rule to be the intermediate data group ; The ground terminal acquires the n-ary data group representing the data to be transmitted according to the array configuration rule and all the intermediate data groups.

In view of the above solutions, the present invention will be described in detail below with reference to the accompanying drawings to the disclosed exemplary embodiments, which will also make other features and advantages of the embodiments of the present invention clear.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

1 is a structural diagram of a communication device in an embodiment;

Figure 2(a) is a flowchart of the execution of the downhole terminal in the embodiment;

Fig. 2(b) is a flowchart of the execution of the ground terminal in the embodiment;

Fig. 3 is the flow chart that S410 is executed in the embodiment;

Fig. 4 is the flow chart that S420 is executed in the embodiment;

5 is a signal to be transmitted modulated by frequency-shift amplitude superposition modulation and demodulation rules in an embodiment;

6 is a signal to be transmitted modulated by frequency shift keying modulation and demodulation rules in an embodiment;

FIG. 7 is a structural diagram of the oil and gas extraction system applied in the embodiment.

Detailed ways

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. The following detailed description sets forth numerous specific details in order to provide a thorough understanding of the various described embodiments. However, it will be apparent to one of ordinary skill in the art that the various described embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.

It will also be understood that, although in some instances the terms "first," "second," etc. are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact could be termed a second contact, and similarly, a second contact could be termed a first contact, without departing from the scope of the various described embodiments. Both the first contact and the second contact are contacts, but they are not the same contact.

The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms "a" ("a", "an") and "the" are intended to include the plural forms as well, unless The context otherwise clearly dictates. It will also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will also be understood that the terms "includes", "including", "comprises" and/or "comprising" when used in this specification are intended to designate the presence of stated features, integers, steps, operations, elements and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groupings thereof.

As used herein, the term "if" is optionally interpreted to mean "when" or "upon" or "in response to determining" or "in response to detecting" depending on the context. Similarly, depending on the context, the phrases "if it is determined that..." or "if a [statement or event] is detected" are optionally interpreted to mean "when determining..." or "in response to determining..." or "on detection of [recited condition or event]" or "in response to detection of [recited condition or event]".

This embodiment discloses a communication device for an extremely low frequency channel of a cased well. In this embodiment, the communication device can selectively ensure the efficiency or quality of signal transmission in the cased well channel where the communication quality is complex and varied.

In this embodiment, the communication device includes a downhole terminal deployed in the cased well and a surface terminal deployed on the formation.

Referring to FIG. 1 , in this embodiment, the downhole terminal includes a data acquisition module, a first processor and a first communication module.

The data acquisition module is configured with several interfaces and protocols that match the respective interfaces, such as TTL, RS485, RS232, zigbee, lora, etc. The data acquisition module is used to collect the data to be transmitted that needs to be sent to the ground terminal through the wireless link and/or wired link; the data to be transmitted includes but is not limited to the status information of the downhole terminal, the sensors in the downhole, the sensing data of the sensors in the downhole, Sensing data include, for example, certain data in cased wells and/or tubing, flow data of downhole fluids, and the like.

The data acquisition module is used to modulate the collected data to be transmitted into a signal to be transmitted according to the current communication rate optimization mode or communication quality optimization mode.

The first communication module sends the modulated signal to be transmitted to the surface terminal outside the cased hole through the extremely low frequency channel in the cased hole.

Specifically, in this embodiment, the downhole terminal implements the modulation steps of the signal to be transmitted, as shown in FIG. 2( a ) and FIG. 2( b ).

S100. The first processor acquires an n-ary data group representing the data to be transmitted, where n is a positive integer.

Wherein, the first processor may select the value of n according to the attribute and value range of the data to be transmitted, etc.

S200. The first processor divides the n-ary data group into a first intermediate data group and a second intermediate data group with the same number of digits according to an array configuration rule.

The number of digits is an odd-numbered n-ary data group, and an odd-numbered number of digits needs to be filled in the n-ary data group. Preferably, the end of the n-ary data group is padded with a digit whose value is 0. Then, the number of bits of the first intermediate data group and the second intermediate data group is n/2 when n is an even number; and (n+1)/2 when n is an odd number.

Preferably, the array configuration rule is to divide the first intermediate data group and the second intermediate data group from left to right. Then, the first data group on the left is the high-order bits of the data to be transmitted, and the second data group on the right is the low-order bits of the data to be transmitted. In the process of signal transmission, it is a preferred option to ensure the accuracy of the first data group to improve the transmission accuracy.

S300. The first processor determines that the communication mode currently configured by the first processor is the communication rate optimization mode or the communication quality optimization mode; enter S410 after determining that the communication mode is the communication rate optimization mode, and enter S420 after determining the communication quality optimization mode.

S410. After judging that the communication mode is the communication rate optimization mode, the first processor defaults that the current extremely low frequency channel of the casing pipe is in a channel state with better communication quality; therefore, the first processor uses a preconfigured frequency shift amplitude superposition modulation The demodulation rule modulates the first intermediate data group and the second intermediate data group into signals to be transmitted.

Among them, the way to improve the communication rate in this embodiment is to realize that the one-bit symbol can carry complex information through the superposition of the frequency and the amplitude. Then, in this embodiment, the first processor modulates the signal to be transmitted by using the amplitude frequency shift superposition modulation rule.

At the same time, it has been clarified in the foregoing embodiments that the first data group is represented as a high bit of the data to be transmitted, and the second data group is represented as a low bit of the data to be transmitted; in combination with the electromagnetic signal in cased wells, the amplitude attenuation is obviously greater than the frequency attenuation. . Then, in this embodiment, frequency shift keying modulation is preferably performed on the first data group, and amplitude keying modulation is performed on the second data group, so that the signal to be transmitted in this embodiment preferentially ensures the representation of the first data group.

S420. After judging that the communication mode is the communication quality optimization mode, the first processor defaults that the current extremely low frequency channel of the casing pipe is in a channel state with poor communication quality; therefore, the first processor uses a frequency shift keying modulation and demodulation The rule or an amplitude keying modulation and demodulation rule modulates the first intermediate data group and the second data group respectively into frequency shift keying or amplitude keying to-be-transmitted sub-signals, and combines these to-be-transmitted sub-signals into a to-be-transmitted signal.

S500. The first processor sends the signal to be transmitted to the ground terminal along the casing well channel.

Through the above technical solution, in this embodiment, the length of the signal to be transmitted is compressed in the communication rate optimization mode, and the information carried by the symbol is increased, so that the underground terminal can send more information to the ground terminal in a unit time, which improves the performance in this embodiment. The communication efficiency of the communication device; in the communication quality optimization mode, the modulation mode of frequency shift keying or amplitude keying makes the information sent by the underground terminal to the surface terminal more stable.

Preferably, for the value of n to be 2, the symbols in the signal to be transmitted are expressed as follows.

；

;

，

表示为码元的频率；

为码元的时间宽度，表示为待传输信号中的时间长度；

是第n为码元的相位常数，以2π为模，取值为0或者π；A表示为码元的振幅。in,

,

is the frequency of symbols;

is the time width of the symbol, expressed as the time length in the signal to be transmitted;

is the phase constant of the nth symbol, which is modulo 2π and takes a value of 0 or π; A represents the amplitude of the symbol.

，

用来表示二进制码元中的1和0，

用来表示二进制码元中的0。in,

,

Used to represent 1s and 0s in binary symbols,

Used to represent 0 in binary symbols.

Optimally, in this embodiment, the specific steps of modulating the signal to be transmitted in S410 by the first processor are shown in FIG. 3 .

S411. The first processor determines x different frequencies {f1, f2..fx} for frequency shift keying modulation according to the extremely low frequency electromagnetic wave carrier frequency, and determines x different amplitudes {A1, A2..Ax}.

Among them, x is an integer greater than or equal to n, that is, the value of each symbol in the first intermediate data group or the second intermediate data group should be able to be represented by the corresponding frequency or amplitude; When a certain bit symbol of the data group takes a value of 1, the frequency corresponding to the symbol is f1, or the corresponding amplitude is A1.

S412: The first processor selects a signal to be transmitted with the same number of bits as the first intermediate data group.

Preferably, when the signal to be transmitted is selected in S412 in this embodiment, a synchronization bit is added at the front end of the signal to be transmitted, and a check bit for parity check or other check methods is added at the back end.

S413, the first processor modulates the first intermediate data group by frequency shift keying, so that the value of each symbol in the first intermediate data group is expressed as the frequency of the corresponding symbol in the signal to be transmitted; and modulates the first intermediate data group by amplitude keying Two intermediate data groups, so that the value of each symbol in the second intermediate data group is expressed as the amplitude of the corresponding symbol in the signal to be transmitted.

Wherein, the frequency of each symbol element of the signal to be transmitted is represented as the value of the corresponding number of bits in the first data group, and the amplitude is represented as the array of the corresponding number of bits in the second data group.

Optimally, in this embodiment, specific steps for modulating the signal to be transmitted by the first processor in S420 are shown in FIG. 4 .

S421. The first processor determines x different frequencies {f1, f2..fx} for frequency shift keying modulation according to the carrier frequency of the extremely low frequency electromagnetic wave, or determines x different amplitudes {A1, f2..fx} for amplitude keying modulation A2..Ax}.

Wherein, x is an integer greater than or equal to n, that is, the value of each symbol in the first intermediate data set and the second intermediate data set should be able to be represented by the corresponding frequency; for example, the first intermediate data set Or when a certain bit symbol of the second intermediate data group takes a value of 1, the frequency corresponding to the symbol is f1.

S422. The first processor modulates the first intermediate data group and the second intermediate data group respectively through frequency shift keying, so that the value of each symbol in the first intermediate data group and the second intermediate data group is represented as the value to be transmitted. The frequency of the corresponding symbol in the sub-signal.

S423. Combine the two sub-signals to be transmitted into a signal to be transmitted according to the array configuration rule.

Preferably, in this embodiment S423, the first intermediate data group and the second intermediate data group can also be modulated by amplitude keying.

In order to more fully describe the steps performed by the downhole terminal in this embodiment.

In this embodiment, it is taken as an example that the downhole terminal sends a certain data of a certain section of downhole bottom fluid obtained from a certain sensor to the surface terminal, and the certain sensing data is 109 .

At the same time, it is assumed that the sensor data collected by the sensor is generally between 0 and 200. Therefore, when the value of n is 2, the binary data group can well represent the sensor data to be transmitted. Meanwhile, the binary data group representing 200 is 1101101, then the number of bits of the binary data group representing the sensing data is an odd number of 7.

S100. The first processor acquires a binary data group representing 109, that is, 1101101.

S200, the first processor complements the binary data group as 11011010, and at the same time divides the n-ary data group into a first intermediate data group and a second intermediate data group with the same number of digits. Then, both the first intermediate data group and the second intermediate data group are 4 digits, wherein the first intermediate data group is 1101, and the second intermediate data group is 1010.

S300. The first processor determines that the communication mode currently configured by the first processor is the communication rate optimization mode or the communication quality optimization mode; enters S411 after judging that the communication mode is the communication rate optimization mode, and enters S421 after judging the communication quality optimization mode.

S411. The first processor determines two different frequencies {f1, f2} for frequency shift keying modulation and two different amplitudes {A1, A2} for amplitude keying modulation according to the extremely low frequency electromagnetic wave carrier frequency.

S412. The first processor selects a signal to be transmitted with the same number of digits as the first intermediate data group, and at the same time adds synchronization bits consisting of several digits at the front end of an intermediate data group, and adds parity consisting of several digits at the back end The check digit of the number.

S413. The first processor modulates the first intermediate data group through frequency shift keying to obtain the frequency of each symbol element of the signal to be transmitted in FIG. 5, that is, {f1, f1, f0, f1}. Through amplitude keying modulation of the second intermediate data group, the symbol amplitude of each bit of the signal to be transmitted in FIG. 5 is obtained, that is, {A1, A0, A1, A0}.

S421. The first processor determines two different frequencies {f1, f2} for frequency shift keying modulation according to the carrier frequency of the extremely low frequency electromagnetic wave, or determines n different amplitudes {A1, A2} for amplitude keying modulation.

S422. The first processor modulates the first intermediate data group and the second intermediate data group respectively through frequency shift keying, so that the value of each symbol in the first intermediate data group and the second intermediate data group is represented as the value to be transmitted. The frequencies of the corresponding symbols in the sub-signal, namely {f1,f1,f0,f1} and {f1,f0,f1,f0}

S423. Combine the two sub-signals to be transmitted according to the array configuration rule to be the signals to be transmitted in FIG. 6, that is, {f1, f1, f0, f1, f1, f0, f1, f0}.

Of course, in this embodiment S423, the first intermediate data group and the second intermediate data group can also be modulated by amplitude keying to obtain the signal to be transmitted, that is, {A1, A1, A0, A1, A1, A0, A1, A0} .

Referring to FIG. 1 , in this embodiment, the ground terminal includes a second communication module, several bandpass filters, a memory, and a second processor.

Wherein, the second communication module is used for receiving the signal to be transmitted sent by the first communication module. Several bandpass filters filter the signal to be transmitted according to the allowed frequency band. The memory mainly includes a stored program area and a stored data area; wherein, the stored program area can store an operating system, an application program required by at least one function, and a program involved in this embodiment. And, the storage data area may store data created according to usage, including relevant setting information or usage information of the application displayed on the display screen involved in the exception of this embodiment. Additionally, memory may include high-speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, and other volatile solid state storage devices. The second processor provides high-speed computing capability and can call and execute programs stored in the memory.

Specifically, in this embodiment, the demodulation steps performed by the ground terminal for the signal to be transmitted are shown in FIG. 2 .

S600. The second processor judges that the current communication mode is the communication rate optimization mode or the communication quality optimization mode; enters S710 after judging that the communication mode is the communication rate optimization mode, and enters S720 after judging the communication quality optimization mode.

Preferably, the second processor obtains the synchronization bit and the parity bit of the signal to be transmitted before demodulation. The second processor determines the start position of the signal to be transmitted according to the synchronization bit; at the same time, confirms the current end position of the signal to be transmitted through the current communication mode.

S710. Select x different bandpass filters, and the frequencies of the x different bandpass filters correspond to {f1, f2...fx} respectively. The second processor passes the to-be-demodulated signal to be transmitted through x band-pass filters and then x filtered signals, and then compares the respective amplitudes and amplitudes {A1, A2...Ax} of each filtered signal to determine each The amplitude of the filtered signal. The second processor combines all the filtered signals into the signal to be transmitted, and configures the amplitude of the corresponding symbol in the signal to be transmitted. The second processor acquires the n-ary data group corresponding to the signal to be transmitted according to the frequency shift amplitude superposition modulation and demodulation rule of the threshold.

S720. Select x different bandpass filters, and the frequencies of the x different bandpass filters correspond to {f1, f2...fx} respectively. The second processor passes the to-be-transmitted signal to be demodulated through the x-bandpass filters and then the x-filtered signals. The second processor combines all the filtered signals into a signal to be transmitted. The second processor demodulates the n-ary data group corresponding to the signal to be transmitted according to the threshold frequency shift keying modulation and demodulation rule.

Of course, if the amplitude keying rule is used to modulate the signal to be transmitted in the previous step, the current n-ary data group can also be obtained by the amplitude keying rule.

S800. The second processor judges the accuracy of the n-ary data group after demodulation according to the check bit, and the check bit is preferably parity check.

S900. The second processor evaluates the communication quality of the current cased hole channel according to the quality of the signal to be transmitted and the data correctness of the data to be transmitted.

Preferably, the communication quality of the current cased well VLF channel is comprehensively evaluated according to the amplitude and packet loss rate of the signal to be transmitted, and the data correctness of the n-ary data group. If the amplitude part of the signal to be transmitted is extremely low, the packet drop rate is high during the demodulation process, or there are many and obvious errors in the data of the n-ary data group, it is judged that the current communication quality is poor, and the communication rate optimization mode should not be used. .

S1000. The second processor selects the communication mode as the communication rate optimization mode or the communication quality optimization mode according to the communication quality, and generates a control instruction according to the selected communication mode.

Preferably, the control command is a binary data, namely 0 or 1; 0 represents the communication quality optimization mode, and 1 represents the communication quality optimization mode.

S1100. The second processor sends a control instruction to the first communication module along the cased well channel through the second communication module.

S1200. The first processor receives a control instruction through the first communication module, and adjusts the current communication mode according to the control instruction.

Through the above technical solution, in this embodiment, the ground terminal demodulates the signal to be transmitted, and obtains an n-ary data group according to the signal to be transmitted, and then can read the data to be transmitted according to the corresponding modulation and demodulation rules; The signal quality of the signal to be transmitted and the data correctness of the data to be transmitted are used to judge the communication quality of the current cased well VLF channel, and then the feedback controls the downhole terminal to select a reasonable communication mode to ensure the signal transmission of the communication device in this embodiment. Always be efficient or stable.

Further, this embodiment discloses a communication method for implementing the aforementioned working steps of the underground terminal and the surface terminal. Steps S100 to S1200 are executed when the communication method is executed.

Meanwhile, when performing the above steps, all or part of the steps of the communication method are not limited to be performed by the underground terminal and/or the surface terminal. For example, S710 to S1200 are performed by a server in a cloud, and the server obtains and outputs related information through interaction with the surface terminal. data, and the processing of related data in the execution steps.

Further, in order to make a clearer description, this embodiment discloses an oil and gas exploitation system using a communication device for reference.

Referring to FIG. 7 , the oil and gas production system in this embodiment includes a casing 4 , an oil pipe 5 , a downhole terminal 1 and a surface terminal 2 .

The casing 4 is a metal pipeline well installed underground by drilling during oil and gas production. The oil pipe 5 is a metal pipe for transporting oil and gas. The casing 4 and the oil pipe 5 are of double-layer coaxial tube structure, and the oil pipe 5 is fitted in the casing 4 with clearance. The gap between the casing 4 and the tubing 5 is filled with a bottom hole fluid 6, and the bottom hole fluid 6 is generally composed of a mixture of clean water, mud, oil and other components. The downhole terminal 1 is immersed in the bottom hole fluid 6 and installed on the tubing 5 , and the surface terminal 2 is deployed in the formation 3 .

Therefore, the channel of the cased well includes metal casing 4 and tubing 5 with extremely low resistivity, bottom hole fluid 6 with complex and unstable composition, and formation 3 whose composition and structure vary with the depth of penetration of the well. Then the channel of the cased well greatly interferes with the transmission and modulation and demodulation of the electromagnetic wave signal, specifically the amplitude attenuation and noise interference of the electromagnetic wave signal. At the same time, the instability of the bottom hole fluid 6 and the formation 3 makes the channel changes of the cased well complex, and it is difficult to improve the communication quality through objective quantitative analysis.

Further, another embodiment of the present invention discloses a communication device. Part of the flow of the communication device in this embodiment is optimized.

In S200, the first processor configures the n-ary data group into m intermediate data groups with the same number of digits according to an array configuration rule, where m is an integer greater than 2.

种不同的矢量振幅。In S411, the first processor determines x different frequencies {f1, f2..fn} for FSK modulation according to the carrier frequency of the extremely low frequency electromagnetic wave, and determines n different amplitudes {A1 for amplitude keying modulation ,A2..An}, which determines the

different vector amplitudes.

In S412, the first processor selects the signal to be transmitted with the same number of bits as an intermediate data group;

In S413, the first processor selects an intermediate data group as a basic data group, and other intermediate data groups are superimposed data groups; modulate the basic data group by frequency shift keying or amplitude keying, so that each symbol in the basic data group is The value of is expressed as the frequency or amplitude of the corresponding symbol in the signal to be transmitted. The first processor modulates the superimposed data group by vector amplitude keying keying, and the value of each symbol in other intermediate data groups is expressed as the vector amplitude of the corresponding symbol in the signal to be transmitted.

Then, through the above technical solution, this embodiment can further compress the length of the signal to be transmitted, that is, divide the n-ary data group into three or more intermediate data groups. At the same time, the symbols of the basic data group are represented by the value of frequency or the value of amplitude, and one or more non-basic data groups are represented by the change of vector amplitude that varies in vector value within the length of one symbol, such as in a symbol The amplitude starts at 0 and ends at 1 within the time length of , which is expressed as A0-2 or f0-2, or within the time length of one symbol, the amplitude starts at 0, the middle is 1, and the end is 0, which is expressed as A0 -1-0.

Through the above technical solutions, the communication device of this embodiment introduces or represents a symbol by a change in vector amplitude, which can further increase the information carried by each symbol in the signal to be transmitted, thereby improving communication efficiency.

In this regard, this embodiment can further divide the communication rate optimization mode into a first-level rate optimization mode and a second-level rate optimization mode with different priorities.

Then, compared with the first-level rate optimization mode in the second-level rate optimization mode, the first processor in this embodiment divides a larger number of intermediate data groups in S200, that is, further compresses the signal length of the signal to be transmitted, thereby increasing the unit The number of signals sent by the downhole terminal to the surface terminal within a time.

Correspondingly, in S1000, the second processor will select the communication mode as the first-level rate optimization mode, the second-level rate optimization mode or the communication quality optimization mode according to the communication quality.

Of course, the communication apparatus in this embodiment can also divide more rate optimization modes with different priorities.

As used herein, the term "including" and the like should be construed as inclusive, ie, "including but not limited to". The term "used for" should be understood as "used at least in part". The terms "one embodiment" or "the embodiment" should be understood to mean "at least one embodiment." The terms "first", "second", etc. may refer to different or the same objects. This document may also include other explicit and implicit definitions.

It should be noted that the embodiments of the present disclosure may be implemented by hardware, software, or a combination of software and hardware. The hardware portion may be implemented using special purpose logic; the software portion may be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or specially designed hardware. Those skilled in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or contained in second processor control code, eg on a programmable memory or a data carrier such as an optical or electronic signal carrier Such code is provided.

Furthermore, although the operations of the methods of the present disclosure are depicted in the figures in a particular order, this does not require or imply that the operations must be performed in the particular order, or that all illustrated operations must be performed to achieve desirable results. Rather, the steps depicted in the flowcharts may change the order of execution. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined to be performed as one step, and/or one step may be decomposed to be performed as multiple steps. It should also be noted that features and functions of two or more devices in accordance with the present disclosure may be embodied in one device. Conversely, the features and functions of one apparatus described above may be further divided into being embodied by multiple apparatuses.

While the present disclosure has been described with reference to several specific embodiments, it is to be understood that the present disclosure is not limited to the specific embodiments disclosed. The present disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. a communication device for a cased well extremely low frequency channel, characterized in that, The communication device includes at least one downhole terminal and one ground terminal; The downhole terminal is configured to, Get the n-ary data group representing the data to be transmitted, where n is an integer greater than 1, According to the array configuration rule, the n-ary data group is divided into a first intermediate data group and a second intermediate data group with the same number of digits; Determine whether the current communication mode is the communication rate optimization mode or the communication quality optimization mode, After judging that the communication mode is the communication rate optimization mode, all the intermediate data groups are modulated into a signal to be transmitted by a superimposed modulation and demodulation rule, sending the signal to be transmitted to the surface terminal along a casing well channel; The ground terminal is configured to, Demodulate the signal to be transmitted into the intermediate data group according to the superposition modulation and demodulation rule; Obtain the n-ary data group representing the data to be transmitted according to the array configuration rule and all intermediate data groups; The downhole terminal modulates the to-be-transmitted signal through the superposition modulation and demodulation rule, and is configured to: Determine n different frequencies {f1, f2..fn} for frequency shift keying modulation according to the carrier frequency of the extremely low frequency electromagnetic wave, and determine n different amplitudes {A1, A2..An} for amplitude keying modulation; selecting the signal to be transmitted with the same number of bits as the first intermediate data group; The first intermediate data group is modulated by frequency shift keying, so that the value of each symbol in the first intermediate data group is expressed as the frequency of the corresponding symbol in the signal to be transmitted, and the frequency of the corresponding symbol in the signal to be transmitted is represented by amplitude keying modulation. the second intermediate data group, so that the value of each symbol in the second intermediate data group is expressed as the amplitude of the corresponding symbol in the to-be-transmitted signal. 2. The communication device for a cased hole ultra-low frequency channel according to claim 1, characterized in that, After judging that the communication mode is the communication quality optimization mode, the downhole terminal modulates the intermediate data group as a sub-signal to be transmitted through a frequency shift keying modulation and demodulation rule or an amplitude keying modulation and demodulation rule, respectively, And combining all the sub-signals to be transmitted is the signal to be transmitted; The ground terminal demodulates the to-be-transmitted signal into the intermediate data group according to the frequency shift keying modulation and demodulation rule or the amplitude keying modulation and demodulation rule. 3. The communication device for cased-hole ultra-low frequency channel according to claim 1, characterized in that, When the value of n is 2, the corresponding symbols in the signal to be transmitted after modulation by frequency shift keying are expressed as:

;

,

is the frequency of symbols;

is the time width of the symbol, expressed as the time length in the signal to be transmitted;

is the phase constant of the nth symbol, which is modulo 2π and takes a value of 0 or π; A is the amplitude of the symbol;

,

Used to represent 1s and 0s in binary symbols,

Used to represent 0 in binary symbols. 4. The communication device for a cased hole very low frequency channel according to claim 1, wherein, The downhole terminal configures the n-ary data group into m intermediate data groups with the same number of digits according to an array configuration rule, where m is an integer greater than 2; The downhole terminal modulates the to-be-transmitted signal through the superposition modulation and demodulation rule, and is configured to: Determine n different frequencies {f1, f2..fn} used for FSK modulation according to the carrier frequency of the extremely low frequency electromagnetic wave, determine n different amplitudes {A1, A2..An} for amplitude keying modulation, determine for vector amplitude key modulation

different vector amplitudes; selecting the signal to be transmitted with the same number of bits as the intermediate data group; One of the intermediate data groups is selected as the basic data group, and the other intermediate data groups are superimposed data groups; the basic data group is modulated by the frequency shift key or the amplitude keying, so that each of the basic data groups is The value of the bit symbol is expressed as the frequency or amplitude of the corresponding symbol in the signal to be transmitted, and the superimposed data group is modulated by the vector amplitude keying, and the value of each symbol in the other intermediate data groups is expressed as the vector amplitude of the corresponding symbol in the signal to be transmitted. 5. The communication device for cased-hole ultra-low frequency channel according to claim 1, characterized in that, The ground terminal is configured with, Evaluate the current communication quality of the cased hole channel according to the quality of the signal to be transmitted and the data correctness of the data to be transmitted; Selecting the communication mode as the communication rate optimization mode or the communication quality optimization mode according to the communication quality, and generating a control command according to the selected communication mode; sending the control command to the downhole terminal along the cased hole channel; The downhole terminal adjusts the communication mode to be the communication rate optimization mode or the communication quality optimization mode according to the control instruction. 6. The communication device for a cased hole very low frequency channel according to claim 1, wherein, The current communication quality configuration of the cased hole channel evaluated by the surface terminal is: The communication quality is evaluated according to the amplitude and packet loss rate of the signal to be transmitted, the data correctness of at least one of the intermediate data groups or the data to be transmitted. 7. A communication method for a cased well extremely low frequency channel, characterized in that, When the method is executed, the steps include: The downhole terminal acquires an n-ary data group representing the data to be transmitted, where n is an integer greater than 1; The downhole terminal divides the n-ary data group into a first intermediate data group and a second intermediate data group with the same number of digits according to an array configuration rule; The downhole terminal judges that the current communication mode is the communication rate optimization mode or the communication quality optimization mode; After judging that the communication mode is the communication rate optimization mode, the downhole terminal modulates all the intermediate data groups into a signal to be transmitted through a superposition modulation and demodulation rule; The downhole terminal sends the signal to be transmitted to the outside along a casing well channel; The ground terminal demodulates the signal to be transmitted into the intermediate data group according to the superimposed modulation and demodulation rule; The ground terminal obtains the n-ary data group representing the data to be transmitted according to the array configuration rule and all intermediate data groups; The downhole terminal modulates the to-be-transmitted signal through the superposition modulation and demodulation rule, and is configured to: Determine n different frequencies {f1, f2..fn} for frequency shift keying modulation according to the carrier frequency of the extremely low frequency electromagnetic wave, and determine n different amplitudes {A1, A2..An} for amplitude keying modulation; selecting the signal to be transmitted with the same number of bits as the first intermediate data group; The first intermediate data group is modulated by frequency shift keying, so that the value of each symbol in the first intermediate data group is expressed as the frequency of the corresponding symbol in the signal to be transmitted, and the frequency of the corresponding symbol in the signal to be transmitted is represented by amplitude keying modulation. the second intermediate data group, so that the value of each symbol in the second intermediate data group is expressed as the amplitude of the corresponding symbol in the to-be-transmitted signal. 8. The communication method for a cased hole very low frequency channel according to claim 7, wherein, After judging that the communication mode is the communication quality optimization mode, the downhole terminal modulates the intermediate data group as a sub-signal to be transmitted through a frequency shift keying modulation and demodulation rule or an amplitude keying modulation and demodulation rule, respectively, And combining all the sub-signals to be transmitted is the signal to be transmitted; The ground terminal demodulates the to-be-transmitted signal into the intermediate data group according to the frequency shift keying modulation and demodulation rule or the amplitude keying modulation and demodulation rule.

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