CN116112822A

CN116112822A - Method and system for transmitting mud pressure wave

Info

Publication number: CN116112822A
Application number: CN202111353867.1A
Authority: CN
Inventors: 王家进; 艾维平; 窦修荣; 毛为民; 王鹏; 贾衡天; 樊懿锋; 魏志刚; 王磊; 郭贤伟
Original assignee: China National Petroleum Corp; CNPC Engineering Technology R&D Co Ltd; Beijing Petroleum Machinery Co Ltd
Current assignee: China National Petroleum Corp; CNPC Engineering Technology R&D Co Ltd; Beijing Petroleum Machinery Co Ltd
Priority date: 2021-11-10
Filing date: 2021-11-10
Publication date: 2023-05-12

Abstract

The invention discloses a method and a system for transmitting mud pressure waves, and relates to the field of petroleum drilling. The method comprises the following steps: obtaining at least one code element according to the change between the wave crest and the wave trough of the carrier wave; the time span of the code element represents the code element width, the code element width is used for coding information comprising a plurality of code elements through a preset coding method, the coded coding information is modulated on a fluid pressure wave and is transmitted, the coding process is simplified through coding the code element time, and the code speed is greatly improved under the condition that other conditions are the same.

Description

Method and system for transmitting mud pressure wave

Technical Field

The invention relates to the field of petroleum drilling, in particular to a method and a system for transmitting mud pressure waves.

Background

The method is the most commonly used method in the underground telemetry technology, however, because the pipeline is very long, usually thousands of meters or even tens of meters long, the high-frequency signal is severely attenuated in the transmission process, and meanwhile, because of the inertia effect of mechanical components, the modulation frequency of the generated signal is very limited, usually a few hertz to tens of hertz, and the bandwidth is limited, so that more information is transmitted in the limited signal bandwidth, and the currently commonly used coding modulation technology is mostly based on the electric communication technology such as amplitude modulation, phase modulation and frequency modulation technology. The technology is not high enough in transmission efficiency of mud pressure waves applied to low bandwidth, particularly in phase modulation signals, and because the change of the phase of mechanical waves cannot be realized rapidly, the technology only adopts continuous phase modulation, so that the symbol duration is increased, the coding efficiency is reduced, and the physical code speed is difficult to exceed the baud rate.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method and a system for transmitting mud pressure waves aiming at the defects of the prior art.

The technical scheme for solving the technical problems is as follows:

a method of transmitting a mud pressure wave, comprising:

obtaining at least one code element according to the change between the wave crest and the wave trough of the carrier wave; wherein the time span of the symbol represents a symbol width;

encoding information including a plurality of symbols at a symbol width by a preset encoding method;

the coded information is modulated onto the fluid pressure wave and information transmission is performed.

The beneficial effects of the invention are as follows: according to the scheme, a code element is obtained according to the change between the wave crest and the wave trough of the carrier wave, the code element width is used for carrying out information coding through a preset coding method, coded information after the information coding is modulated on a fluid pressure wave for carrying out information transmission, the code element time is used for coding, the coding process is simplified, and the code speed is greatly improved under the condition that other conditions are the same.

Further, the obtaining a symbol according to the change between the carrier wave crest and the carrier wave trough specifically includes:

a symbol is obtained based on multiple, one or fractional changes between the peaks and troughs of the carrier wave.

The beneficial effects of adopting the further scheme are as follows: the scheme obtains one code element unit through different code element widths so as to adapt to different information codes.

By utilizing the waveform change characteristic during continuous phase modulation and taking half-period waveform as a basic coding unit, the inter-code interference is eliminated, and the limited bandwidth is fully utilized.

Further, the preset encoding method includes: binary or multilevel coding.

The beneficial effects of adopting the further scheme are as follows: the scheme is suitable for different application scenes through various coding modes.

The binary phase modulation is adopted, and under the same baud rate, the scheme can improve the code speed by 1/3, and the improvement of any physical cost is not involved, and the higher error rate is not caused, because the waveform characteristics are identical.

Further, the method further comprises the following steps:

when decoding the received coding information, comparing the detected code element width with a preset fundamental frequency period;

and judging the multiple relation between the code element width and a preset fundamental frequency period according to the comparison result, and obtaining coding information according to the multiple relation.

The beneficial effects of adopting the further scheme are as follows: by the scheme, the half-period modulation coding can be equivalent to half-period frequency modulation signal processing because the scheme does not directly code the phase, so that the coding process is simplified.

Further, before decoding the received encoded information, further comprising: and receiving a mud pressure wave, recording the coding information of the mud pressure wave, and determining the coding information of the mud pressure wave as the received coding information.

The beneficial effects of adopting the further scheme are as follows: the mud pressure wave is decoded by recording the encoded information.

The other technical scheme for solving the technical problems is as follows:

a mud pressure wave transmission system, comprising: the device comprises a recording module, a coding module and a modulation transmission module;

the recording module is used for obtaining at least one code element according to the change between the wave crest and the wave trough of the carrier wave; wherein the time span of the symbol represents a symbol width;

the coding module is used for coding information comprising a plurality of code elements with the code element width through a preset coding method;

the modulation transmission module is used for modulating the coded information to the fluid pressure wave for information transmission.

Further, the recording module is specifically configured to obtain a symbol according to multiple, one or multiple changes between the peak and the trough of the carrier wave.

Further, the preset encoding method includes: binary or multilevel coding.

Further, the method further comprises the following steps: the decoding module is used for comparing the width of the detected code element with a preset fundamental frequency period when decoding the received coded information;

Further, the method further comprises the following steps: and the receiving module is used for receiving the mud pressure wave, recording the coding information of the mud pressure wave and determining the coding information recorded in the mud pressure wave as the received coding information.

Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a schematic flow chart of a method for transmitting mud pressure waves according to an embodiment of the present invention;

FIG. 2 is a block diagram of a system for transmitting mud pressure waves according to an embodiment of the present invention;

FIG. 3 is a diagram of a code waveform according to other embodiments of the present invention;

FIG. 4 is a diagram of a conventional code waveform provided by other embodiments of the present invention;

fig. 5 is a decoding flow chart according to other embodiments of the present invention.

Detailed Description

The principles and features of the present invention are described below with reference to the drawings, the illustrated embodiments are provided for illustration only and are not intended to limit the scope of the present invention.

As shown in fig. 1, a method for transmitting mud pressure waves according to an embodiment of the present invention includes:

s1, obtaining at least one code element according to the change between the wave crest and the wave trough of a carrier wave; wherein the time span of the symbol represents a symbol width;

in one embodiment, one or several changes between the wave crest and the wave trough of the carrier wave can be used as one coding unit, namely a code element;

s2, carrying out information coding on coding information comprising a plurality of code elements by a preset coding method with the width of the code elements; in an embodiment, the preset encoding method may include: coding with symbol width, i.e. peak to trough, or trough to peak time span, related to carrier frequency; the peak-to-valley switching is completed in half or fractional periods of the fundamental frequency period, whether from high level to low level or from low level to high level, and is denoted as state 0 or 1, and the fundamental frequency is exemplified by, but not limited to, high frequency conversion, and may be reversed, as long as the peak-to-valley switching is completed in one complete fundamental frequency period or in a period different from the state 0 or 1 in a period of several fundamental frequency periods including fractional fundamental frequency periods.

In one embodiment, the symbol width may be an integer multiple of the fundamental symbol, i.e., the fundamental half period, or a fraction thereof. In one embodiment, the coding state may be a plurality of states corresponding to a plurality of symbol widths, that is, not limited to binary coding, but may be multi-level coding, but the basic principle is consistent.

In one embodiment, the binary code may be a code consisting of two basic characters '0', '1'. Wherein, the code element: a "one bit" binary code. Codeword: n symbols may constitute different combinations, any one of which is called a codeword. The operation rule is: the rule of binary code operation is every two times. Such as decimal 1, binary also 1; but decimal 2 (1+1), binary 10; decimal 3 (1+1+1), binary 11; decimal 4, binary 100, and so on, decimal addition with binary is every binary.

In one embodiment, each digit of the decimal is represented by a 4-bit binary number code, referred to as a BCD code, i.e., a "binary decimal code". The usual BCD code is 8421-BCD code, which uses 4-bit binary numbers to represent 1-bit decimal numbers, and the bit weight corresponding to each binary bit from left to right is 8, 4, 2, 1. Because the 4-bit binary number has 16 states of 0000-1111, and the decimal number 0-9 only takes 10 states of 0000-1001, the other 6 are not used.

Each digit of the decimal system is represented by a 4-bit binary number, each bit having a fixed weight. Thus, it is referred to as a weighted code or weighted code. The weight of each bit of the 8421 code from high to ten can be expressed as:

D＝8b3+4b2+2b1+1b0,

each decimal number represented by the 8421 code is identical to the common binary representation, or the binary code corresponding to each decimal number is a binary number equivalent to the decimal number. Thus, among the 8421 codes, there are 6 codes (1010,1011, 1100, 1101, 1110, 1111) that are unlikely to occur, also called illegal 8421 codes. When any decimal number is written as 8421 code, each digit of the decimal number is converted into the corresponding 8421 code, and conversely, any decimal number represented by 8421 code can be conveniently converted into a common decimal number form.

In one embodiment, the multi-system encoding may further include: decimal and hexadecimal codes,

hexadecimal coding is a representation of data in a computer. Unlike our daily decimal notation. It is composed of 0-9, A-F. The correspondence with 10 scale is: 0-9 corresponds to 0-9; A-F corresponds to 10-15; the number of N system can be represented by the number 0- (N-1) to be more than 9 by letters A-F, and the letters, numbers or other objects can be coded into numbers by a preset method, or information and data can be converted into preset electric pulse signals. The code is widely used in the fields of electronic computers, televisions, remote control, communication and the like. Encoding is the process of converting information from one form or format to another. Decoding is the inverse of encoding.

And S3, modulating the coded information to the fluid pressure wave, and transmitting the information.

In one embodiment, the mud pulser artificially changes the fluid pressure in a pipeline with fluid circulation by adjusting the opening of a throttle valve to form a pressure wave according to the change of the opening of the throttle valve, and then codes information and modulates the information to the fluid pressure wave for information transmission. The time interval between adjacent solid lines is one fundamental period, illustrated by binary coding of two symbol widths as shown in fig. 3, with the first two solid lines being shown as the time required for the mud pulser pendulum valve to go all the way from closed to open, and then to closed. With the half-cycle encoding of the present invention, the time intervals are represented in fig. 3 as the intervals of adjacent solid lines and dashed lines. As shown in FIG. 3, 3 times of phase shift occurs in 6 fundamental frequency periods, and according to the coding method of the invention, 9bits of information is coded altogether, in FIG. 4, single-period coding is adopted, 3 times of phase shift occurs in 6 fundamental frequency periods, 6bits of information is coded altogether, and compared with FIG. 3 and FIG. 4, the half-period coding code speed is improved by 50%. The method of the invention is more general, assuming that the probability of 1 and 0 appearing in the information flow is basically equal, adopting half-period coding, 2bits of information can be coded in 1.5 fundamental frequency periods on average, 4/3bits of information can be coded in a single period on average, and compared with 1bit of information coded in a single period, the average code speed can be improved by 1/3. More importantly, compared with the prior art, the scheme of the invention does not involve any improvement of physical cost, and cannot lead to higher error rate, because the characteristic waveforms of the scheme and the scheme are identical.

In order to fully utilize the high code rate characteristic of the high frequency carrier, before coding modulation, the information can be pre-coded, the probability of the state 0 or 1 is improved as much as possible during pre-coding, the probability difference between the occurrence probabilities of the two coding states is as large as possible, and the state with high probability is coded on the high frequency carrier, namely the short code element, so that the code rate can be further improved.

In one embodiment, the mud pulser can be operated by encoding the downhole parameters sensed by the sensor in a specific manner to generate a pulse signal that controls the upward and downward movement of the pulser's small control valve, and the force of the recirculating mud is used to cause the mushroom head to move upward and downward in a synchronized manner, thus changing the cross-sectional area of the mud flow between the mushroom head and the underlying restrictor ring. In the state that the mushroom head is lifted, mud in the drill string can smoothly pass through the flow limiting ring; in the mushroom head inserted condition, the cross-sectional area of mud flow is reduced, thereby creating a positive mud pressure pulse within the drill string. The pulse signal generated by the directional probe controls the time of the mushroom head in the lifted or inserted state, thereby controlling the width and interval of the pulses. The mud flow sectional area between the mushroom head and the flow limiting ring determines the strength of signals, and the strength of the signals can be controlled by selecting the outer diameter of the mushroom head and the inner diameter of the flow limiting ring, so that the flow limiting ring is suitable for working environments with different wellbores, different displacement and different well depths. In practice, the whole process involves how data is acquired downhole and how it is delivered to the surface, both functions being performed by the probe and mud pulse generator, respectively.

According to the scheme, a code element is obtained according to the change between the wave crest and the wave trough of the carrier wave, the code element width is used for carrying out information coding through a preset coding method, coded information after the information coding is modulated on a fluid pressure wave for carrying out information transmission, the code element time is used for coding, the coding process is simplified, and the code speed is greatly improved under the condition that other conditions are the same.

Preferably, in any of the foregoing embodiments, the obtaining a symbol according to the change between the carrier wave peak and the carrier wave trough specifically includes:

In one embodiment, the symbol width may be an integer multiple of the fundamental symbol, i.e., the fundamental half period, or a fraction thereof.

The scheme obtains one code element unit through different code element widths so as to adapt to different information codes.

Preferably, in any of the foregoing embodiments, the preset encoding method includes: binary or multilevel coding.

The scheme is suitable for different application scenes through various coding modes.

Preferably, in any of the above embodiments, the method further includes:

when decoding the received coding information, comparing the detected code element width with a preset fundamental frequency period; the preset fundamental frequency period may be a carrier period or a fluid pressure wave period.

In one embodiment, illustrated by the binary coding of two symbol widths shown in fig. 3, the time interval between adjacent solid lines is one fundamental period, the first two solid lines being shown as the time required for the mud pulser pendulum valve to go from closed to open and then to close. With the half-cycle encoding of the present invention, the time intervals are represented in fig. 3 as the intervals of adjacent solid lines and dashed lines. As shown in FIG. 3, 3 times of phase shift occurs in 6 fundamental frequency periods, and according to the coding method of the invention, 9bits of information is coded altogether, in FIG. 4, single-period coding is adopted, 3 times of phase shift occurs in 6 fundamental frequency periods, 6bits of information is coded altogether, and compared with FIG. 3 and FIG. 4, the half-period coding code speed is improved by 50%. The method of the invention is more general, assuming that the probability of 1 and 0 appearing in the information flow is basically equal, adopting half-period coding, 2bits of information can be coded in 1.5 fundamental frequency periods on average, 4/3bits of information can be coded in a single period on average, and compared with 1bit of information coded in a single period, the average code speed can be improved by 1/3.

By the scheme, the half-period modulation coding can be equivalent to half-period frequency modulation signal processing because the scheme does not directly code the phase, so that the coding process is simplified.

Preferably, in any of the above embodiments, before decoding the received encoded information, the method further includes: and receiving a mud pressure wave, recording the coding information of the mud pressure wave, and determining the coding information of the mud pressure wave as the received coding information. In a certain embodiment, the decoding process is performed by comparing the detected peak-to-valley switching time with a set fundamental frequency period, and judging the multiple relationship between the switching time and the fundamental frequency period, so as to obtain the coding information.

In a certain embodiment, as shown in fig. 5, when the signal is decoded, it is necessary to detect the peaks and the troughs of the received signal, record the time width between the peaks and the troughs, and compare the time of the peak-to-trough conversion with a preset fundamental frequency period and a preset coding scheme, so as to obtain the code element represented by each peak-to-trough conversion. Taking the signal of fig. 3 as an example, when the signal is received, 9 peak-to-valley transitions are detected, representing that the signal contains 9bits of information. And (3) comparing the obtained time of each peak-to-valley conversion with the fundamental frequency period. In this example, a symbol represented by a conversion time of half a fundamental period is defined as 0, and a symbol represented by a conversion time of one fundamental period is defined as 1, so that the symbol information recorded in the received signal is 001 011 0 00.

The mud pressure wave is decoded by recording the encoded information.

In one embodiment, as shown in FIG. 2, a system for transmitting mud pressure waves, comprises: a recording module 1101, a coding module 1102 and a modulation transmission module 1103;

the recording module 1101 is configured to obtain at least one symbol according to a change between a peak and a trough of a carrier wave; wherein the time span of the symbol represents a symbol width;

the encoding module 1102 is configured to encode encoding information including a plurality of symbols with a symbol width by a preset encoding method; in an embodiment, the preset encoding method may include: coding with symbol width, i.e. peak to trough, or trough to peak time span, related to carrier frequency; the peak-to-valley switching is completed in half or fractional periods of the fundamental frequency period, whether from high level to low level or from low level to high level, and is denoted as state 0 or 1, and the fundamental frequency is exemplified by, but not limited to, high frequency conversion, and may be reversed, as long as the peak-to-valley switching is completed in one complete fundamental frequency period or in a period different from the state 0 or 1 in a period of several fundamental frequency periods including fractional fundamental frequency periods.

The modulation transmission module 1103 is configured to modulate the encoded information onto a fluid pressure wave and perform information transmission.

Preferably, in any of the above embodiments, the recording module 1101 is specifically configured to obtain one symbol according to multiple, one or multiple variations between the peak and the trough of the carrier wave.

Preferably, in any of the above embodiments, the method further includes: the decoding module is used for comparing the width of the detected code element with a preset fundamental frequency period when decoding the received coded information;

Preferably, in any of the above embodiments, the method further includes: and the receiving module is used for receiving the mud pressure wave, recording the coding information of the mud pressure wave and determining the coding information recorded in the mud pressure wave as the received coding information.

The mud pressure wave is decoded by recording the encoded information.

In a certain embodiment, the decoding process is performed by comparing the detected peak-to-valley switching time with a set fundamental frequency period, and judging the multiple relationship between the switching time and the fundamental frequency period, so as to obtain the coding information.

It is to be understood that in some embodiments, some or all of the alternatives described in the various embodiments above may be included.

It should be noted that, the foregoing embodiments are product embodiments corresponding to the previous method embodiments, and the description of each optional implementation manner in the product embodiments may refer to the corresponding description in the foregoing method embodiments, which is not repeated herein.

The reader will appreciate that in the description of this specification, a description of terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of elements is merely a logical functional division, and there may be additional divisions of actual implementation, e.g., multiple elements or components may be combined or integrated into another system, or some features may be omitted, or not performed.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment of the present invention.

In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention is essentially or a part contributing to the prior art, or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of the embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-only memory (ROM), a random access memory (RAM, randomAccessMemory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The present invention is not limited to the above embodiments, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the present invention, and these modifications and substitutions are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims

1. A method of transmitting a mud pressure wave, comprising:

2. The method according to claim 1, wherein the obtaining a symbol according to the change between the peak and the trough of the carrier wave comprises:

3. A method of transmitting a mud pressure wave as claimed in claim 1 or claim 2, wherein the pre-set encoding method comprises: binary or multilevel coding.

4. A method of transmitting a mud pressure wave as claimed in claim 1 or claim 2, further comprising:

5. The method of claim 4, further comprising, prior to decoding the received encoded information: and receiving a mud pressure wave, recording the coding information of the mud pressure wave, and determining the coding information of the mud pressure wave as the received coding information.

6. A mud pressure wave transmission system, comprising: the device comprises a recording module, a coding module and a modulation transmission module;

the modulation transmission module is used for modulating the coded information to the fluid pressure wave and transmitting the information.

7. The system of claim 6, wherein the recording module is configured to obtain a symbol based on a plurality of, one or a plurality of changes between the peaks and the troughs of the carrier wave.

8. A mud pressure wave transmission system as claimed in claim 6 or claim 7, wherein the pre-set encoding method comprises: binary or multilevel coding.

9. A mud pressure wave transmission system as claimed in claim 6 or claim 7, further comprising: the decoding module is used for comparing the width of the detected code element with a preset fundamental frequency period when decoding the received coded information;

10. A mud pressure wave transmission system, further comprising: and the receiving module is used for receiving the mud pressure wave, recording the coding information of the mud pressure wave and determining the coding information recorded in the mud pressure wave as the received coding information.