CN112350804A

CN112350804A - Communication device and method for cased well extremely low frequency channel

Info

Publication number: CN112350804A
Application number: CN202110005119.8A
Authority: CN
Inventors: 余沐阳; 刘昶; 周凯; 倪谢霆; 陈庆; 李红斌
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2021-01-05
Filing date: 2021-01-05
Publication date: 2021-02-09
Anticipated expiration: 2041-01-05
Also published as: CN112350804B

Abstract

The invention discloses a communication method and a communication device for a cased well extremely-low frequency channel. The communication device comprises an underground terminal and a ground terminal; the underground terminal is configured to obtain an n-system data group representing data to be transmitted, wherein n is an integer larger than 1, divide the n-system data group into at least two intermediate data groups with the same number of bits according to an array configuration rule, judge a current communication mode, modulate all the intermediate data groups into signals to be transmitted through a superposition modulation and demodulation rule after judging that the communication mode is a communication rate optimization mode, and transmit the signals to be transmitted to the ground terminal along a casing well channel; the ground terminal is configured to demodulate a signal to be transmitted into an intermediate data group according to the superposition modulation and demodulation rule; and acquiring an n-system data group representing the data to be transmitted according to the array configuration rule and all the intermediate data groups. The invention can maintain the efficiency of signal transmission under the casing well channel with extremely low resistivity.

Description

Communication device and method for cased well extremely low frequency channel

Technical Field

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

Background

The intelligent development of the traditional oil and gas industry is the trend of times, and under the background, the concept of the intelligent oil field is generated at the same time.

The informatization is the basis of intellectualization, but the domestic oil and gas exploitation operation process is still limited by the prior art, and the real-time monitoring of the underground operation data cannot be realized.

Therefore, engineering parameter and geological parameter design for monitoring downhole operation in real time is an important subject of oil and gas exploitation engineering.

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

the sound wave signals are greatly attenuated at the oil pipe joint, and are greatly influenced by engineering operation noise, so that the signal transmission is seriously influenced.

The resistivity of the cased well channel environment is extremely low, and the attenuation of the electromagnetic wave signal intensity is large.

Oil well communication needs to be far away, and long-distance electromagnetic wave communication carriers generally use low-frequency carriers, so that the channel transmission bandwidth is small, and the transmission rate is slow.

The novel communication modes used in communication, such as frequency hopping communication and OFDM, improve the signal-to-noise ratio and reduce the communication rate. Meanwhile, the underground space is narrow, the hardware volume is limited, and the complex communication mode is difficult to realize.

The oil well space is narrow and small, and the environment is complicated, has higher requirements to technical indicators such as communication device hardware volume hardware temperature resistance, leads to the realization of novel communication methods such as frequency hopping communication and OFDM comparatively difficult.

Disclosure of Invention

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

Specifically, the communication device comprises at least one underground terminal and a ground terminal;

the underground terminal is configured to obtain an n-system data group representing data to be transmitted, wherein n is an integer larger than 1, the n-system data group is divided into at least two intermediate data groups with the same number of bits according to an array configuration rule, a current communication mode is judged to be a communication rate optimization mode or a communication quality optimization mode, after the communication mode is judged to be the communication rate optimization mode, all the intermediate data groups are modulated into signals to be transmitted through a superposition modulation and demodulation rule, and the signals to be transmitted are transmitted to the ground 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; and acquiring the n-system data group representing the data to be transmitted according to the array configuration rule and all the intermediate data groups.

Further, the present embodiments disclose a hydrocarbon production system. The oil gas exploitation system comprises a casing and an oil pipe; the casing is drilled to communicate the stratum and the oil layer; the oil pipe is in clearance fit in the sleeve; the gap between the casing and the oil pipe is filled with a well bottom fluid, and the gap between the casing and the oil pipe and the well bottom fluid form a cased well channel; the downhole terminal is submerged in a bottom fluid and mounted to the tubing, and the surface terminal is deployed in a formation.

Further, the present embodiment discloses a communication method. The method when executed comprises the steps of: the method comprises the steps that an underground terminal obtains an n-system data group representing data to be transmitted, wherein n is an integer larger than 1; the underground terminal divides the n-system data groups into at least two intermediate data groups with the same digits according to an array configuration rule; the underground terminal judges that the current communication mode is a communication rate optimization mode or a communication quality optimization mode; after judging that the communication mode is a communication rate optimization mode, the underground terminal modulates all the intermediate data sets into a signal to be transmitted through a superposition modulation and demodulation rule; the underground terminal sends the signal to be transmitted to the outside along a sleeve well channel; the ground terminal demodulates the signal to be transmitted into the intermediate data group according to the superposition modulation and demodulation rule; and the ground terminal acquires the n-system 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, other features and advantages of the disclosed exemplary embodiments will become apparent from the following detailed description of the disclosed exemplary embodiments, which proceeds with reference to the accompanying drawings.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a block diagram of a communication apparatus according to an embodiment;

FIG. 2(a) is a flow chart of an embodiment of a downhole terminal;

fig. 2(b) is a flowchart executed by the ground terminal in the embodiment;

FIG. 3 is a flowchart illustrating the execution of S410 in the embodiment;

FIG. 4 is a flowchart illustrating the execution of S420 in one embodiment;

FIG. 5 is a signal to be transmitted modulated according to the frequency shift amplitude superposition modulation-demodulation rule in the embodiment;

FIG. 6 is a diagram illustrating a signal to be transmitted modulated according to a FSK modulation/demodulation rule in an embodiment;

fig. 7 is a block diagram of a hydrocarbon recovery system used in an embodiment.

Detailed Description

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various described embodiments. It will be apparent, however, to one skilled 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 as not to unnecessarily obscure aspects of the embodiments.

It will also be understood that, although the terms first, second, etc. may be used herein to describe various elements in some cases, 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 can be termed a second contact, and, similarly, a second contact can be termed a first contact, without departing from the scope of the various described embodiments. The first contact and the second contact are both 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," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. 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 be further understood that the terms "comprises," "comprising," "includes," and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

As used herein, the term "if" is optionally to be interpreted to mean "when … …" ("where" or "upon") or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrase "if determined … …" or "if [ stated condition or event ] is detected" is optionally to be construed to mean "upon determination … …" or "in response to determination … …" or "upon detection of [ stated condition or event ] or" in response to detection of [ stated condition or event ] ", depending on the context.

The present embodiments disclose a communication device for cased hole very low frequency channels. The communication device in the embodiment can selectively ensure the efficiency or quality of signal transmission in the cased hole channel with complex and variable communication quality.

The communication device in this embodiment includes a downhole terminal deployed in a cased hole and a surface terminal deployed on the formation.

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

The data acquisition module is provided with a plurality of interfaces and protocols matched with the respective interfaces, such as TTL, RS485, RS232, zigbee, lora and the like. The data acquisition module is used for collecting data to be transmitted which needs to be sent to the ground terminal through a wireless link and/or a wired link; the data to be transmitted includes, but is not limited to, status information of the downhole terminal, various downhole sensors, sensing data of the downhole sensors, such as certain data in a cased well and/or an oil pipe, flow data of downhole fluid, and the like.

The data acquisition module is used for modulating the collected data to be transmitted into signals to be transmitted according to the current communication rate optimization mode or the communication quality optimization mode.

The first communication module sends the modulated signal to be transmitted to a ground terminal outside the cased well through a very low frequency channel in the cased well.

Specifically, the steps of modulating the signal to be transmitted by the downhole terminal in this embodiment are shown in fig. 2(a) and fig. 2 (b).

S100, a first processor obtains an n-system data group representing data to be transmitted, wherein n is a positive integer.

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

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

The number of bits is an odd number of n-ary data groups, and an odd number of bits need to be complemented in the n-ary data groups. Preferably, the n-ary data set is complemented by a number of bits having a value 0. The number of bits of the first intermediate data set and the second intermediate data set is n/2 when n is an even number; and (n + 1)/2 when n is an odd number.

Preferably, the array arrangement 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 upper bits of the data to be transmitted, and the second data group on the right is the lower bits of the data to be transmitted. During the signal transmission process, the priority for ensuring the accuracy of the first data group is the preference for improving the transmission precision.

S300, the first processor judges whether the communication mode configured by the first processor is a communication rate optimization mode or a communication quality optimization mode; the method proceeds to S410 after determining that the communication mode is the communication rate optimization mode, and proceeds to S420 after determining that 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 modulates the first intermediate data group and the second intermediate data group into signals to be transmitted through a pre-configured frequency shift amplitude superposition modulation and demodulation rule.

In this embodiment, the manner of increasing the communication rate is to superpose the frequency and the amplitude, so that one bit of symbol can carry complex information. Then, in this embodiment, the first processor modulates the signal to be transmitted by the amplitude frequency shift superposition modulation rule.

Meanwhile, in the foregoing embodiments, it has been explained that the first data group represents the upper bits of data to be transmitted, and the second data group represents the lower bits of data to be transmitted; and the characteristic that the amplitude attenuation of the electromagnetic signal in the cased well is obviously higher than the frequency attenuation is combined. Then, in this embodiment, the frequency shift keying modulation is preferably performed on the first data set, and the amplitude keying modulation is preferably performed on the second data set, so that the signal to be transmitted in this embodiment preferentially guarantees the representation of the first data set.

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 modulates the first intermediate data group and the second data group into the sub-signals to be transmitted after frequency shift keying or amplitude shift keying respectively through a frequency shift keying modulation and demodulation rule or an amplitude shift keying modulation and demodulation rule, and combines the sub-signals to be transmitted into the signals to be transmitted.

S500, the first processor sends a signal to be transmitted to the ground terminal along a sleeve well channel.

By the technical scheme, the length of the signal to be transmitted is compressed in the communication rate optimization mode, and the information carried by the code element is increased, so that the underground terminal can send more information to the ground terminal in unit time, and the communication efficiency of the communication device in the embodiment is improved; and under the communication quality optimization mode, the underground terminal can send information to the ground terminal more stably through a modulation mode of frequency shift keying or amplitude keying.

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

；

Wherein the content of the first and second substances,

；

is the time width of the code element and is expressed as the time length in the signal to be transmitted;

the nth is the phase constant of the code element, takes 2 pi as a module and takes the value of 0 or pi;

wherein the content of the first and second substances,

，

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

to represent a0 in a binary symbol.

Preferably, in this embodiment, fig. 3 shows a specific step of the first processor modulating the signal to be transmitted in S410.

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

Wherein 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 represented by a corresponding frequency or amplitude; for example, when a bit symbol of the first intermediate data group takes a value of 1, the frequency corresponding to the symbol is f1, or the amplitude corresponding to the symbol is a 1.

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

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

S413, the first processor modulates the first intermediate data group through frequency shift keying, so that the numerical value of each bit code element in the first intermediate data group is represented as the frequency of a corresponding code element in the signal to be transmitted; and modulating the second intermediate data set by amplitude keying so that the value of each bit code element in the second intermediate data set is represented as the amplitude of the corresponding code element in the signal to be transmitted.

The frequency of each bit code element of the signal to be transmitted is represented as the numerical value of the corresponding bit number in the first data group, and the amplitude is represented as the array of the corresponding bit number in the second data group.

Preferably, in this embodiment, fig. 4 shows a specific step of the first processor modulating the signal to be transmitted in S420.

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

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

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

And S423, combining the two sub-signals to be transmitted into the signal to be transmitted according to the array configuration rule.

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

The steps performed by the downhole terminal in this embodiment are described more fully.

This embodiment is exemplified by the downhole terminal sending some data of some section of downhole fluid obtained from some sensor to the surface terminal, and some sensed data is 109.

Meanwhile, the sensing data collected by the sensor is generally between 0 and 200, so that when the value of n is 2, the binary data group can well represent the sensing data to be transmitted. Meanwhile, the binary data group representing 200 is 1101101, the number of bits of the binary data group representing the sensing data is odd 7.

S100, the first processor acquires a binary data set of the representation 109, namely 1101101.

S200, the first processor complement binary data set is 11011011010, and the n-system data set is divided into a first intermediate data set and a second intermediate data set which have the same number of bits. Then the first intermediate data set and the second intermediate data set are both 4 bits, where the first intermediate data set is 1101 and the second intermediate data set is 1010.

S300, the first processor judges whether the communication mode configured by the first processor is a communication rate optimization mode or a communication quality optimization mode; after the communication mode is determined to be the communication rate optimization mode, the process proceeds to S411, and after the communication quality optimization mode is determined, the process proceeds to S421.

S411, the first processor determines 2 different frequencies { f1, f2} for frequency shift keying modulation and 2 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 bits as the first intermediate data group, and simultaneously adds a synchronization bit composed of a plurality of bits at the front end of one intermediate data group and a check bit composed of a plurality of bits at the rear end.

S413, the first processor modulates the first intermediate data group by frequency shift keying to obtain the frequency of each bit symbol of the signal to be transmitted in fig. 5, i.e., { f1, f1, f0, f1 }. The symbol amplitude of each bit of the signal to be transmitted in fig. 5, i.e., { a1, a0, a1, a0}, is obtained by amplitude-keying modulation of the second intermediate data group.

S421, the first processor determines 2 different frequencies { f1, f2} for frequency shift keying modulation or n different amplitudes { A1, A2} for amplitude keying modulation according to the carrier frequency of the extremely low frequency electromagnetic wave.

S422, the first processor modulates the first intermediate data set and the second intermediate data set respectively by frequency shift keying, so that the value of each bit symbol in the first intermediate data set and the second intermediate data set represents the frequency of the corresponding symbol in the sub-signal to be transmitted, namely { f1, f1, f0, f1} and { f1, f0, f1, f0}

And S423, combining the two sub-signals to be transmitted into the signals to be transmitted in the graph 6 according to the array configuration rule, namely { f1, f1, f0, f1, f1, f0, f1 and f0 }.

Certainly, 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 signals to be transmitted, i.e., { a1, a1, a0, a1, a1, a0, a1, a0 }.

Referring to fig. 1, the ground terminal in this embodiment includes a second communication module, a plurality of band pass filters, a memory, and a second processor.

The second communication module is used for receiving the signal to be transmitted sent by the first communication module. The band-pass filters filter the signal to be transmitted according to the allowed frequency band. The memory mainly comprises a program storage area and a data storage area; the storage program area may store an operating system, an application program required for at least one function, a program related to the present embodiment, and the like. And, the storage data area may store data created according to the use, including related setting information or use condition information of an application displayed on the display screen, etc., which are related to outside the present embodiment. In addition, the 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 is capable of calling and executing programs stored in the memory.

Specifically, the step of demodulating the signal to be transmitted by the ground terminal in this embodiment is shown in fig. 2.

S600, the second processor judges that the current communication mode is a communication rate optimization mode or a communication quality optimization mode; the process proceeds to S710 after the communication mode is determined to be the communication rate optimization mode, and the process proceeds to S720 after the communication quality optimization mode is determined.

Preferably, the second processor acquires the synchronization bits and the check bits of the signal to be transmitted before demodulation. The second processor determines the initial position of the signal to be transmitted according to the synchronization bit; and meanwhile, confirming the termination position of the current signal to be transmitted through the current communication mode.

S710, selecting x different band-pass filters, wherein the frequencies of the x different band-pass filters correspond to { f1, f2... fx }. The second processor respectively leads the signal to be transmitted to be demodulated to pass through x filtering signals after x band-pass filters, and then determines the amplitude of each filtering signal by comparing the respective amplitude of each filtering signal with the amplitude { A1, A2.. Ax }. The second processor combines all the filtered signals into a signal to be transmitted and configures the amplitude of the corresponding code element in the signal to be transmitted. And the second processor acquires an n-system data group corresponding to the signal to be transmitted according to the frequency shift amplitude superposition modulation and demodulation rule of the threshold value.

S720, selecting x different band-pass filters, wherein the frequencies of the x different band-pass filters correspond to { f1, f2... fx }. The second processor respectively passes the signals to be demodulated to be transmitted through x filtered signals after x band-pass filters. The second processor combines all the filtered signals into a signal to be transmitted. And the second processor demodulates the n-system data group corresponding to the signal to be transmitted according to the frequency shift keying modulation and demodulation rule of the threshold value.

Of course, if the signal to be transmitted is modulated in the preceding step using the amplitude keying rule, it is also possible to obtain the n-ary data set in the present case by means of the amplitude keying rule.

And S800, the second processor judges the accuracy of the demodulated n-system data group according to the check bit, wherein the check bit is preferably parity check.

And S900, evaluating the communication quality of the current cased hole channel by the second processor 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 hole extremely-low frequency channel is comprehensively evaluated according to the amplitude and the packet loss rate of the signal to be transmitted and the data correctness of the n-system data group. If the amplitude part of the signal to be transmitted is extremely low or the packet drop rate is high in the demodulation process or more and obvious errors occur in the data of the n-system data group, the current communication quality is judged to be poor, and a communication rate optimization mode is not used.

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

Preferably, the control instruction is a binary data, i.e. 0 or 1; 0 denotes a communication quality optimization mode, and 1 denotes a communication quality optimization mode.

S1100, the second processor sends a control command to the first communication module through the second communication module along the cased hole channel.

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

By the technical scheme, the ground terminal demodulates the signal to be transmitted, acquires the n-system data group according to the signal to be transmitted, and can read the data to be transmitted according to the corresponding modulation and demodulation rule; meanwhile, the ground terminal judges the communication quality of the current cased well extremely-low frequency channel according to the signal quality of the signal to be transmitted and the data correctness of the data to be transmitted, and then the underground terminal is controlled to select a reasonable communication mode in a feedback mode, so that the signal transmission of the communication device in the embodiment is always kept efficient or stable.

Further, the present embodiment discloses a communication method for implementing the working steps of the downhole terminal and the surface terminal. The communication method is executed to perform steps S100 to S1200.

Meanwhile, all or part of the steps of the communication method are not limited to be performed by the downhole terminal and/or the surface terminal when the steps are performed, for example, S710 to S1200 are performed by a server in a cloud, and the server acquires and outputs related data through interaction with the surface terminal, and performs processing on the related data in the steps.

Further, for clarity of illustration, the present embodiment discloses a hydrocarbon production system employing 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.

Wherein the casing 4 is a metal tubing well installed into the ground by drilling during production of oil and gas. The oil pipe 5 is a metal pipeline for transporting oil and gas. The casing 4 and the oil pipe 5 are of a double-layer coaxial pipe barrel structure, and the oil pipe 5 is in clearance fit in the casing 4. The gap between the casing 4 and the oil pipe 5 is filled with bottom fluid 6, and the bottom fluid 6 is generally formed by mixing clean water, slurry, oil and the like. The downhole terminal 1 is submerged in a bottom fluid 6 and mounted in a tubing 5 and the surface terminal 2 is deployed in the formation 3.

Therefore, the channel of the cased well comprises a casing 4 and an oil pipe 5 which are made of metal with extremely low resistivity, a bottom fluid 6 with complex and unstable components, and a stratum 3 with composition structure changing along with the depth of the well. The transmission and modem interference of the cased hole to the electromagnetic wave signal, specifically, the amplitude attenuation and noise interference of the electromagnetic wave signal, is very large. Meanwhile, the instability of the bottom liquid 6 and the stratum 3 makes the channel change of the cased well complicated, and the communication quality is difficult to improve through objective quantitative analysis.

Further, another embodiment of the present invention discloses a communication device. In the present embodiment, part of the flow of the communication apparatus is optimized.

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

In S411, the first processor determines x different frequencies { f1, f2.. fn } for frequency shift keying modulation, n different amplitudes { A1, A2. An } for amplitude keying modulation, and n different amplitudes { A1, A2. An } for vector amplitude key modulation based on the very low frequency electromagnetic wave carrier frequency

Different vector amplitudes are provided.

In S412, the first processor selects a 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 the other intermediate data groups as overlay data groups; and modulating the basic intermediate data set by frequency shift keying or amplitude shift keying, so that the numerical value of each bit code element in the basic data set is represented as the frequency or amplitude of the corresponding code element in the signal to be transmitted. The first processor modulates the superimposed data set by vector amplitude keying, and the numerical value of each bit code element in other intermediate data sets is represented as the vector amplitude of the corresponding code element in the signal to be transmitted.

Through the technical scheme, the length of the signal to be transmitted can be further compressed, namely the n-system data group is divided into three or more intermediate data groups. While the symbols of the basic data set are represented by values of frequency or values of amplitude and one or more non-basic data sets are represented by vector amplitude variations in vector value variations over a symbol length, such as amplitude of 0 starting and 1 ending and represented as a0-2 or f0-2 over the time length of a symbol or amplitude of 0 starting and 1 in the middle and ending and represented as a0-1-0 over the time length of a symbol.

Through the technical scheme, the communication device introduces or represents the code elements by vector amplitude change, information carried by each code element in the signals to be transmitted can be further increased, and further communication efficiency is improved.

In this regard, the present embodiment can further divide the communication rate optimization mode into the first-level rate optimization mode and the 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 of this embodiment divides the intermediate data group into a greater number in S200, that is, further compresses the signal length of the signal to be transmitted, thereby increasing the number of signals sent by the downhole terminal to the ground terminal in unit time.

Accordingly, the second processor selects the communication mode as a primary rate optimization mode, a secondary rate optimization mode, or a communication quality optimization mode according to the communication quality in S1000.

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

As used herein, the terms "comprises," comprising, "and the like are to be construed as open-ended inclusions, i.e.," including, but not limited to. The term "for" should be understood as "at least partially for". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first," "second," and the like may refer to different or the same object. Other explicit and implicit definitions may also be included herein.

It should be noted that the embodiments of the present disclosure can be realized by hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portion may be stored in a memory for execution by a suitable instruction execution system, such as a micro-second processor 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 embodied in second processor control code, such code being provided, for example, in programmable memory or on a data carrier such as an optical or electronic signal carrier.

Further, while the operations of the methods of the present disclosure are depicted in the drawings in a particular order, this does not require or imply that these operations must be performed in this particular order, or that all of the 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 combined into one step execution, and/or one step broken down into multiple step executions. It should also be noted that the features and functions of two or more devices according to the present disclosure may be embodied in one device. Conversely, the features and functions of one apparatus described above may be further divided into embodiments by a plurality of apparatuses.

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

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A communication device for cased hole very low frequency channels,

the communication device comprises at least one underground terminal and a ground terminal;

the downhole terminal is configured such that,

acquiring an n-system data group representing data to be transmitted, wherein n is an integer greater than 1,

dividing the n-system data groups into at least two intermediate data groups with the same number of bits according to an array configuration rule,

judging whether the current communication mode is a communication rate optimization mode or a communication quality optimization mode,

after the communication mode is judged to be the communication rate optimization mode, modulating all the intermediate data groups into a signal to be transmitted by a superposition modulation and demodulation rule,

transmitting the signal to be transmitted to the ground terminal along a cased well channel;

the ground terminal is configured such that,

demodulating the signal to be transmitted into the intermediate data group according to the superposition modulation and demodulation rule;

and acquiring the n-system data group representing the data to be transmitted according to the array configuration rule and all the intermediate data groups.

2. The communication device for cased hole very low frequency channels of claim 1,

after the underground terminal judges that the communication mode is a communication quality optimization mode, the underground terminal modulates the intermediate data set into the sub-signals to be transmitted respectively according to a frequency shift keying modulation and demodulation rule or an amplitude shift keying modulation and demodulation rule, and combines all the sub-signals to be transmitted into the signals to be transmitted;

and the ground terminal demodulates the signal to be transmitted into the intermediate data set according to the frequency shift keying modulation and demodulation rule or the amplitude shift keying modulation and demodulation rule.

3. The communication device for cased hole very low frequency channels of claim 1,

the underground terminal configures the n-system data groups into a first intermediate data group and a second intermediate data group with the same digits according to an array configuration rule;

the downhole terminal modulates the signal to be transmitted according to the superposition modulation and demodulation rule and is configured to:

determining n different frequencies { f1, f2.. fn } for frequency shift keying modulation and n different amplitudes { a1, a2.. An } for amplitude keying modulation from the very low frequency electromagnetic wave carrier frequency;

selecting the signal to be transmitted with the same number of bits as the first intermediate data group;

and modulating the second intermediate data group by amplitude keying to make the numerical value of each bit code element in the second intermediate data group be represented as the amplitude of the corresponding code element in the signal to be transmitted.

4. The communication device for cased hole very low frequency channels of claim 3,

when the value of n is 2, the corresponding code element in the signal to be transmitted after the modulation by the frequency shift keying is expressed as:

；

wherein the content of the first and second substances,

；

the time width of the code element is expressed as the time length in the signal to be transmitted;

wherein the content of the first and second substances,

，

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

to represent a0 in a binary symbol.

5. The communication device for cased hole very low frequency channels of claim 1,

the underground terminal configures the n-system data groups into m intermediate data groups with the same digits according to an array configuration rule, wherein m is an integer greater than 2;

n different frequencies f1, f2., fn for frequency shift keying modulation, n different amplitudes A1, A2, An for amplitude key modulation, and n different amplitudes for vector amplitude key modulation are determined based on the very low frequency electromagnetic wave carrier frequency

Different vector amplitudes;

selecting the signal to be transmitted with the same number of bits as the intermediate data group;

selecting one intermediate data set as a basic data set, and selecting other intermediate data sets as superposed data sets; and modulating the basic intermediate data set through the frequency shift key or the amplitude keying so that the numerical value of each bit code element in the basic data set is represented as the frequency or the amplitude of the corresponding code element in the signal to be transmitted, modulating the superimposed data set through the vector amplitude keying, and representing the numerical value of each bit code element in other intermediate data sets as the vector amplitude of the corresponding code element in the signal to be transmitted.

6. The communication device for cased hole very low frequency channels of claim 1,

the ground terminal is provided with a ground terminal,

evaluating the communication quality of the current cased well 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 instruction according to the selected communication mode;

transmitting the control instructions to the downhole terminal along the cased hole channel;

and the underground terminal adjusts the communication mode into the communication rate optimization mode or the communication quality optimization mode according to the control instruction.

7. The communication device for cased hole very low frequency channels of claim 1,

the surface terminal evaluates the communication quality of the current cased hole channel and configures the communication quality as follows:

and evaluating the communication quality according to the amplitude and the packet loss rate of the signal to be transmitted and the data correctness of at least one intermediate data group or the data to be transmitted.

8. A communication method for a cased hole very low frequency channel,

the method when executed comprises the steps of:

the method comprises the steps that an underground terminal obtains an n-system data group representing data to be transmitted, wherein n is an integer larger than 1;

the underground terminal divides the n-system data groups into at least two intermediate data groups with the same digits according to an array configuration rule;

the underground terminal judges that the current communication mode is a communication rate optimization mode or a communication quality optimization mode;

after judging that the communication mode is a communication rate optimization mode, the underground terminal modulates all the intermediate data sets into a signal to be transmitted through a superposition modulation and demodulation rule;

the underground terminal sends the signal to be transmitted to the outside along a sleeve well channel;

the ground terminal demodulates the signal to be transmitted into the intermediate data group according to the superposition modulation and demodulation rule;

and the ground terminal acquires the n-system data group representing the data to be transmitted according to the array configuration rule and all the intermediate data groups.

9. The method of communicating for cased hole very low frequency channels of claim 8,