Drilling fluid pulse data encoding and decoding method and device

Abstract

The present disclosure relates to a drilling fluid pulse data encoding and decoding method and device, a controller, a storage medium, and a computer program product. The drilling fluid pulse data encoding method comprises: obtaining a data value of a preset radix, the data value representing a measured value of a drilling parameter; dividing the data value into code values having a fixed number of bits; and on the basis of the code values, selecting, from among a plurality of different types of data chirp signals, one type of data chirp signal corresponding to the code values to encode the code values, so as to obtain a data signal. The embodiments of the present disclosure effectively improve data transmission reliability and applicability in various drilling fluid channels.

Description

A method and device for encoding and decoding drilling fluid pulse data TECHNICAL FIELD

[0001] The present disclosure relates to the field of drilling engineering in oil and gas exploration and development, and in particular, to a method and device for encoding and decoding drilling fluid pulse data, a controller, a storage medium, and a computer program product. BACKGROUND

[0002] With the continuous development of horizontal wells, directional wells, cluster wells technology, the application of measurement while drilling technology is becoming more and more common. Drilling fluid pulse transmission is the most widely used data transmission method in the drilling process, and its basic principle is to control the downhole pulse generator to move according to certain encoding modulation rules, constantly change the drilling fluid pressure in the drill pipe, and transmit the measurement data to the ground in the form of pressure wave pulses. The transmission rate is usually below 1 bps.

[0003] However, with the continuous deepening of oil and gas exploration and development at home and abroad, the use of high-end drilling measurement and control equipment such as drilling while logging, engineering parameters, and rotary steering is gradually increasing, and the amount of data that needs to be uploaded to the ground from downhole has increased significantly. The conventional pulse transmission technology is difficult to meet the requirements. Continuous wave drilling fluid pulse transmission technology can increase the data transmission rate by more than 10 times, which is one of the important means to solve the above problems. The common signal modulation methods currently used for continuous wave drilling fluid pulse transmission technology mainly include amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK), etc. These continuous wave signal modulation methods are all based on sinusoidal waves. For example, for binary ASK, "0" is transmitted by a sinusoidal wave signal with an amplitude of 0, and "1" is transmitted by a sinusoidal wave signal with an amplitude of 1, while the frequency and initial phase remain unchanged; for binary FSK, "0" is transmitted by a sinusoidal wave signal with a frequency of 12 Hz, and "1" is transmitted by a sinusoidal wave signal with a frequency of 24 Hz, while the amplitude and initial phase remain unchanged; for binary PSK, "0" is transmitted by a signal with a phase of 0, and "1" is transmitted by a signal with a phase of π.

[0004] Under the same transmitting power condition, the transmission rate of the multi-modulation is higher than that of the binary modulation, but the continuous wave has a smaller frequency or phase interval due to the multi-modulation, resulting in a higher bit error rate than that of the binary modulation. In addition, the signal modulation based on the sine wave usually only utilizes one or several frequencies in the frequency band, and the bandwidth is narrow. If the interference to the modulation frequency used in the channel is large, the signal transmission will be greatly affected, the bit error rate will be increased, and even the decoding or demodulation at the receiving end will fail. Therefore, how to improve the reliability and applicability of data transmission in different drilling fluid channels is a problem to be solved. SUMMARY

[0005] Embodiments of the present disclosure provide a drilling fluid pulse data encoding and decoding method, device, controller, storage medium and computer program product to improve the reliability and applicability of data transmission in different drilling fluid channels.

[0006] In a first aspect, embodiments of the present disclosure provide a drilling fluid pulse data encoding method, comprising:

[0007] obtaining a data value of a preset modulation, the data value representing a measured value of a drilling parameter;

[0008] dividing the data value into a code value of a fixed number of bits; and

[0009] based on the code value, selecting a type of data Chirp signal corresponding to the code value from a plurality of different types of data Chirp signals to encode the code value to obtain a data signal.

[0010] The plurality of different types of data Chirp signals are not identical to each other in terms of the functional relationship between frequency and time, and the number of the plurality of different types of data Chirp signals is equal to the number of different values represented by the code value of the fixed number of bits. The frequency variation ranges of the plurality of different types of data Chirp signals are the same, and include nonlinear data Chirp signals. The plurality of different types of data Chirp signals have the same duration.

[0011] Alternatively, the frequency variation ranges of the plurality of different types of data Chirp signals can be the same, and include nonlinear data Chirp signals. Alternatively, the frequency variation ranges of the plurality of different types of data Chirp signals can be different, and include linear and / or nonlinear data Chirp signals. The functional relationship between the frequency and time of the nonlinear data Chirp signal is a non-linear function.

[0012] Further, the drilling fluid pulse data transmission rate, the number of the plurality of different types of data Chirp signals, and the duration satisfy the following equation: B = log2(N) / T

[0013] wherein B represents the drilling fluid pulse data transmission rate, N represents the number of the data Chirp signals, and T represents the duration of the data Chirp signals.

[0014] The drilling fluid pulse data encoding method further comprises attaching a preamble signal in front of the data signal to form encoded data, the preamble signal being used to indicate the start position of the data signal, wherein the preamble signal comprises a plurality of different types of preamble Chirp signals.

[0015] The plurality of different types of preamble Chirp signals are not identical to each other in terms of the functional relationship between the frequency and the time of the preamble Chirp signals. The duration of the preamble Chirp signals is greater than the duration of the data Chirp signals.

[0016] Further, the preamble Chirp signals satisfy at least one of the following:

[0017] The durations of the plurality of different types of preamble Chirp signals are different;

[0018] The frequency variation ranges of the plurality of different types of preamble Chirp signals are different, and the preamble Chirp signals comprise linear and / or nonlinear preamble Chirp signals; or

[0019] The frequency variation ranges of the plurality of different types of preamble Chirp signals are the same, and the preamble Chirp signals comprise nonlinear preamble Chirp signals. The functional relationship between the frequency and the time of the nonlinear preamble Chirp signals is a non-linear function.

[0020] The functional relationship between the frequency and the time of the preamble Chirp signals is not identical to the functional relationship between the frequency and the time of the preamble Chirp signals. The data values are binary data values, and the code values are binary code values, and the fixed number of bits is greater than or equal to 2.

[0021] A second aspect of the embodiments of the present disclosure provides a method for decoding drilling fluid pulse data, comprising: receiving a pressure wave pulse signal, wherein the pressure wave pulse signal comprises a pressure wave pulse signal representing a data signal, wherein the data signal represents a measured value of a drilling parameter and is formed by encoding different types of data Chirp signals; determining a starting time position of the data signal representing the value of the drilling parameter in the pressure wave pulse signal; dividing the pressure wave pulse signal corresponding to the data signal into time blocks according to the transmission duration of each data Chirp signal based on the starting time position of the data signal; cross-correlating a plurality of reference data Chirp signals of different types with the pressure wave pulse signal in the time blocks to determine the data Chirp signal corresponding to the pressure wave pulse signal in the time block of the data signal; and determining the code value represented by the time block of the data signal based on the corresponding data Chirp signal.

[0022] wherein the code value is a binary code value, and the number of bits of the code value is greater than or equal to 2.

[0023] The pressure wave pulse signal comprises a pressure wave pulse signal representing a preamble signal, the preamble signal indicating the starting position of the data signal and being composed of a plurality of different types of preamble Chirp signals, wherein determining the starting time position of the data signal representing the value of the drilling parameter in the pressure wave pulse signal comprises:

[0024] Cross-correlating a plurality of reference sub-preamble signals with the pressure wave pulse signal respectively to obtain correlation values;

[0025] Comparing the correlation values with a predetermined threshold value;

[0026] Determining one or more starting time positions based on one or more reference sub-preamble signals whose correlation values are greater than the predetermined threshold value; and

[0027] Determining the median of the one or more starting time positions to determine the starting time position of the data signal,

[0028] wherein the reference sub-preamble signals are constructed based on the preamble Chirp signals used in the encoding stage and the order of the corresponding preamble Chirp signals.

[0029] Further, cross-correlating a plurality of reference data Chirp signals of different types with the pressure wave pulse signal in the time blocks to determine the data Chirp signal corresponding to the pressure wave pulse signal in the time block of the data signal comprises:

[0030] For each time block, cross-correlating each of the plurality of reference data Chirp signals with the pressure wave pulse signal in the time block to obtain a correlation value; and

[0031] determining the reference data Chirp signal with the largest correlation value as the data Chirp signal corresponding to the waveform in the time block,

[0032] wherein the reference data Chirp signals are various types of data Chirp signals used to form a data signal in an encoding process.

[0033] The method for decoding drilling fluid pulse data further comprises:

[0034] filtering and / or equalizing the pressure wave pulse signal to remove interference noise in the pressure wave pulse signal.

[0035] A third aspect of the embodiments of the present disclosure provides a drilling fluid pulse encoding device, comprising:

[0036] a controller, and

[0037] a drilling fluid pulse generator,

[0038] wherein the controller is configured to perform the method for encoding drilling fluid pulse data according to the first aspect of the present disclosure to obtain encoded data, and control the drilling fluid pulse generator to generate a pressure wave pulse signal based on the encoded data.

[0039] A fourth aspect of the embodiments of the present disclosure provides a drilling fluid pulse decoding device, comprising:

[0040] a computing device, and

[0041] a pressure sensor,

[0042] the computing device is configured to receive a pressure wave pulse signal from the pressure sensor, and perform the method for decoding drilling fluid pulse data according to the second aspect of the present disclosure.

[0043] A fourth aspect of the embodiments of the present disclosure provides a controller, comprising:

[0044] one or more processors, and

[0045] a computer-readable storage medium comprising executable instructions stored thereon, which, when executed by the one or more processors, implement the method for encoding and decoding drilling fluid pulse data according to the second aspect or the third aspect of the present disclosure.

[0046] A fifth aspect of the embodiments of the present disclosure provides a machine-readable storage medium comprising executable instructions stored thereon, which, when executed by one or more processors, implement the method for encoding and decoding drilling fluid pulse data according to the second aspect or the third aspect of the present disclosure.

[0047] A sixth aspect of the embodiments of the present disclosure provides a computer program product comprising executable instructions that, when executed by one or more processors, implement the drilling fluid pulse data encoding method and decoding method according to the second aspect or the third aspect of the present disclosure.

[0048] The drilling fluid pulse data encoding and decoding method, device, controller, storage medium and computer program product provided by the present disclosure are based on combination of multiple types of Chirp signals to construct a preamble Chirp signal, and utilize multiple cross-correlations and median value taking to improve signal synchronization accuracy; data Chirp signals corresponding to different code values are constructed, and signal modulation is implemented on a preset radix measurement value by the preamble Chirp signal and the data Chirp signal. Further, signal demodulation is implemented by utilizing cross-correlation characteristics of different data Chirp signals. Compared with traditional single Chirp signal synchronization and sinusoidal wave signal data stream modulation and demodulation, the reliability and applicability of data transmission in different drilling fluid channels are effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0049] The accompanying drawings illustrate various examples of aspects of the present disclosure and are used in conjunction with the description to explain the principles of the present disclosure. Those skilled in the art will appreciate that the specific embodiments shown in the drawings are merely illustrative and are not intended to limit the scope of the present disclosure. It should be recognized that one element shown in one example can also be designed as multiple elements, or multiple elements can also be combined as one element. In some examples, an element shown as an internal component of another element can also be implemented as an external component of the other element, or vice versa. In the drawings:

[0050] FIG. 1 shows a schematic diagram of a drilling fluid pulse data transmission system according to an embodiment of the present disclosure;

[0051] FIG. 2 shows a flowchart of a method of processing and encoding measurement values to form a data signal according to an embodiment of the present disclosure;

[0052] FIG. 3 shows a data stream constituted by binary data values of various parameters according to an embodiment of the present disclosure;

[0053] FIG. 4 shows a correspondence between Chirp signals and code values according to an embodiment of the present disclosure;

[0054] FIG. 5 shows a frequency-time curve diagram of eight types of Chirp signals according to an embodiment of the present disclosure;

[0055] FIG. 6 shows a time-domain waveform diagram of eight types of Chirp signals according to an embodiment of the present disclosure;

[0056] FIG. 7 shows an encoded signal comprising a preamble signal and a data signal according to an embodiment of the present disclosure;

[0057] FIG. 8 shows time-domain waveform diagrams of four preamble Chirp signals according to embodiments of the present disclosure;

[0058] FIG. 9 shows a time-domain diagram of a preamble signal combining the four preamble Chirp signals according to embodiments of the present disclosure;

[0059] FIG. 10 shows a flowchart of a method of decoding a drilling fluid pressure wave pulse signal according to embodiments of the present disclosure;

[0060] FIG. 11 shows a reference sub-preamble signal and a pressure wave pulse signal cross-correlation result according to embodiments of the present disclosure;

[0061] FIG. 12 shows a data signal being divided into a plurality of data signal time blocks of duration T according to embodiments of the present disclosure;

[0062] FIG. 13 shows drilling fluid channel attenuation characteristics;

[0063] FIG. 14 shows time-domain waveforms of eight sinusoidal signals of different frequencies after channel attenuation;

[0064] FIG. 15 shows a reference sinusoidal signal of different frequencies and a channel-attenuated sinusoidal signal cross-correlation result according to embodiments of the present disclosure;

[0065] FIG. 16 shows time-domain waveforms of different data Chirp signals after channel attenuation according to embodiments of the present disclosure;

[0066] FIG. 17 shows a reference Chirp signal of different types and a channel-attenuated data Chirp signal cross-correlation result according to embodiments of the present disclosure;

[0067] FIG. 18 shows a preamble signal after channel attenuation and noise interference according to embodiments of the present disclosure;

[0068] FIG. 19 shows a preamble signal cross-correlation result after channel attenuation and noise interference according to embodiments of the present disclosure; and

[0069] FIG. 20 shows a controller according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0070] As used in the following, the terms "have", "comprise" or "include" or any arbitrary grammatical variations thereof shall be understood as non-exclusive, i.e. as meaning "have", "comprise", "include" and / or "consist of". In other words, these terms are used in the sense of including but not necessarily limited to.

[0071] Furthermore, it shall be noted that the terms "at least one", "one or more" or similar expressions indicating that a feature or element can exist once or more than once, will typically be used only once when introducing the respective feature or element. In the following, in most cases, when referring to the respective feature or element, the expressions "at least one" or "one or more" will not be repeated, although the fact is that the respective feature or element can exist once or more than once.

[0072] Furthermore, as used in the following, the terms "preferably", "more preferably", "particularly", "more particularly", "specifically", "more specifically" or similar terms are used in conjunction with optional features, i.e. features which are not essential for the technical workability of the disclosure. Thus, the features introduced by these terms are optional features and do not limit the scope of the claims in any way. As the skilled person will appreciate, the disclosure can be embodied with alternative features. Similarly, features introduced by "in an embodiment of the disclosure" or similar expressions are intended to be optional features and do not limit alternative embodiments of the disclosure in any way, nor the scope of the disclosure, nor the possibility that optional features introduced in this way can be combined with other optional or non-optional features of the disclosure.

[0073] It will also be understood that, although the terms "first", "second" etc. can be used herein to describe various elements, these elements should not be limited by these terms. The terms are only used to distinguish one element from another.

[0074] It is noted that the steps shown in the flowcharts of the drawings can be executed in a computer system comprising computer-executable instructions, such as a set of computer-executable instructions, and although a logical order is shown in the flowcharts, in some cases the steps shown or described can be executed in an order different from the one presented herein.

[0075] The specific implementation of the embodiments of the present disclosure is described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiments of the present disclosure, and is not used to limit the present disclosure. Moreover, for the sake of brevity, only the components closely related to the embodiments of the present disclosure are described in detail below.

[0076] First, referring to FIG. 1, a schematic diagram of a drilling fluid pulse data transmission system according to an embodiment of the present disclosure is shown. The system includes a pulse encoding device and a pulse decoding device.

[0077] As shown, the pulse encoding device is located in the wellbore, including a measuring device 10, a controller 20, and a drilling fluid pulse generator 30. The measuring device 10 can be various sensors that perform various measurements to obtain measurement values during drilling, such as obtaining values of directional parameters, engineering parameters, and geological parameters. In practical applications, the directional parameters include inclination, azimuth, tool face, etc., the engineering parameters include weight on bit, torque, etc., and the geological parameters include gamma value, resistivity, etc. The measuring device 10 provides the measurement values to the controller 20. The controller 20 is configured to convert the measurement values from the measuring device 10 into preset numeral data values, and to use a Chirp signal to signal-modulate and encode the preset numeral data values to form an encoded signal. The encoded signal includes a preamble signal and a data signal, where the preamble signal is used to indicate the start of the data signal, and the data signal is used to indicate the measurement values of the measured various parameters. The controller then provides the encoded signal to the drilling fluid pulse generator 30. The drilling fluid pulse generator 30 is configured to generate a drilling fluid pressure wave pulse signal based on the encoded signal. Alternatively, the controller can control the drilling fluid pulse generator 30 to generate the drilling fluid pressure wave pulse signal based on the encoded signal. The drilling fluid pressure wave pulse signal is transmitted to the surface in the drilling fluid.

[0078] The pulse decoding device is located on the surface, including a pressure sensor 40, a surface interface box 50, and a computer device 60. The pressure sensor 40 is used to collect the drilling fluid pressure wave pulse signal to generate corresponding pressure wave data; the surface interface box 50 is used to process the pressure wave data, and to transmit the processed pressure wave data to the computer device 60. The computer device 60 receives the processed pressure wave data and performs decoding of the drilling fluid pressure wave pulse signal to obtain the measurement values of various parameters downhole. Those skilled in the art can understand that the surface interface box 50 is not necessary, and the pressure sensor 40 can directly transmit the collected pressure wave data to the computer device 60, and the computer device 60 decodes the pressure wave data to obtain the downhole measurement values.

[0079] Next, refer to Fig. 2, which discloses a flow chart of a method of processing and encoding measurement values to form a data signal according to an embodiment of the present disclosure, which can be performed by the controller 20 in Fig. 1 or by other processing units. The method starts at step 210, where the controller receives various measurement values from the measurement device, such as measurement values of directional parameters, engineering parameters and geological parameters. Then the method proceeds to step 220, where the measurement values are converted to data values in a preset number system, such as binary data values. Additionally, to increase the transmission rate, multiple binary data values (data values of different types of parameters) can be concatenated to form a data stream. For example, refer to Fig. 3, which shows a data stream composed of binary data values of various parameters according to an embodiment of the present disclosure. In Fig. 3, the upper layer shows various parameter types or names, such as inclination parameters, azimuth parameters, tool face parameters and temperature parameters, etc., the middle layer shows corresponding measurement values of the various parameters, and the lower layer shows binary data values of the various parameters, which are concatenated to form a data stream of binary data values. The method proceeds to step 230, where the data values are segmented into code values of a fixed number of bits. The fixed number of bits is greater than or equal to 2. For example, the binary data values are segmented into multiple three-bit binary code values. Then at step 240, Chirp signals corresponding to the code values are selected to encode the code values. Refer to Fig. 4, which shows a correspondence between Chirp signals and code values according to an embodiment of the present disclosure, where the Chirp signals corresponding to the code values are referred to as data Chirp signals. In Fig. 4, the data values or data stream are segmented into multiple three-bit binary code values, and then based on each binary code value, a Chirp signal corresponding to the binary code value is selected to encode or modulate the code value, thereby forming an encoded data signal. The encoding process includes encoding code values of a fixed number of bits (such as three-bit binary code values) into Chirp signals of a corresponding type. In an embodiment of the present disclosure, the Chirp signals corresponding to code values of a specific number of bits can be referred to as data Chirp signals.

[0080] A Chirp signal is a signal whose instantaneous frequency varies with time, and the relationship between the frequency f and the time t can be expressed as: f = f(t). Since the instantaneous frequency varies with time, each Chirp signal occupies a wide signal frequency band, has strong adaptability to channel noise, and has good autocorrelation. In an embodiment of the present disclosure, each Chirp signal can represent, for example, a three-bit binary code value, greatly increasing the data transmission rate and improving the data transmission accuracy.

[0081] In an embodiment of the present disclosure, taking binary code values as an example, different binary code values correspond to different types of data Chirp signals. For example, in the case of using three-bit binary code values, code values 000, 001, 010, 011, 100, 101, 110, and 111 correspond to different types of data Chirp signals respectively, each type of data Chirp signal represents a corresponding three-bit binary code value, and therefore 8 different types of data Chirp signals are needed to correspond to different three-bit binary code values (i.e., the number of different types of data Chirp signals is equal to the number of different values represented by code values of a fixed number of bits). The meaning of different types of data Chirp signals is that the data Chirp signals are not the same in terms of frequency variation range and / or function relationship between frequency and time. The transmission duration of each data Chirp signal is the same so as to perform data signal decoding in a subsequent coding process, and the number of types (N) of data Chirp signals and the transmission duration (T) of each data Chirp signal can determine the target transmission rate B. For example, for binary code values, the target transmission rate B is determined as follows: B = log2(N) / T

[0082] B represents the target transmission rate, with the unit of bps (bits per second); N represents the number of types of data Chirp signals; and T represents the transmission duration of data Chirp signals, with the unit of s. log2(N) is the number of bits of a binary number corresponding to the number N of types of data Chirp signals, with the unit of bit.

[0083] For example, if a transmission rate of 3 bps is needed, 8 types of data Chirp signals can be used, and the transmission duration of each data Chirp signal is 1 s; or 64 types of data Chirp signals can be used, and the transmission duration of each data Chirp signal is 2 s.

[0084] Different types of data Chirp signals can be constructed in different ways. For example, taking the case of three-bit binary code values as an example, 8 different types of data Chirp signals can be constructed in various ways, for example, different types of data Chirp signals are constructed to be in different frequency variation ranges, such as:

[0085] Code value 000 corresponds to the first type of Chirp signal, and the frequency variation range of the Chirp signal is, for example, 0-10 Hz;

[0086] Code value 001 corresponds to the second type of Chirp signal, and the frequency variation range of the Chirp signal is, for example, 5-15 Hz;

[0087] The code value 010 corresponds to a third type of Chirp signal, the frequency variation range of which is, for example, 10-20 Hz;

[0088] The code value 011 corresponds to a fourth type of Chirp signal, the frequency variation range of which is, for example, 15-25 Hz;

[0089] The code value 100 corresponds to a fifth type of Chirp signal, the frequency variation range of which is, for example, 20-30 Hz;

[0090] The code value 101 corresponds to a sixth type of Chirp signal, the frequency variation range of which is, for example, 25-35 Hz;

[0091] The code value 110 corresponds to a seventh type of Chirp signal, the frequency variation range of which is, for example, 30-40 Hz; and

[0092] The code value 111 corresponds to an eighth type of Chirp signal, the frequency variation range of which is, for example, 35-45 Hz.

[0093] Those skilled in the art should understand that the frequency variation ranges of the above-mentioned data Chirp signals are exemplary, and any other suitable frequency variation ranges can be adopted under the teaching of the present disclosure, and the respective frequency variation ranges can not overlap. In the case where the different types of data Chirp signals are in different frequency ranges, the functional relationship between the frequency f and the time t can be, for example, a linear relationship, expressed as: f = f(t) = f0+ k x t

[0094] wherein f0is the initial frequency, i.e., the frequency at t = 0;

[0095] k is the slope, representing the rate of change of the frequency with respect to time, in units of hertz per second (Hz / s);

[0096] t is the time variable.

[0097] In the case where the frequency f varies linearly with respect to the time t (i.e., a linear Chirp signal), if the span of each frequency variation range is the same, 10 Hz, and the duration is 1 s, as listed above, the slope k of each type of data Chirp signal is the same. Different types of Chirp signals are distinguished by the initial frequency f0. The frequency variation ranges of the Chirp signals listed above overlap with each other, but those skilled in the art can understand that the above-mentioned frequency variation ranges can not overlap.

[0098] According to another example of the present disclosure, in order to increase the degree of distinction between different types of Chirp signals and avoid signal interference, the functional relationship between the frequency f and the time t of the data Chirp signal can be a nonlinear relationship (nonlinear Chirp signal).

[0099] For example, 8 data Chirp signals are selected, each with a duration of, for example, 1 s, to achieve a transmission rate of 3 bps, and the frequency of the different types of data Chirp signals varies with time as follows:

[0100] The code value 000 corresponds to the first type of Chirp signal, and the frequency of the Chirp signal varies with time as follows, for example: f(t) = sqrt(386.6065^2 - (t x 100 - 192.2574)^2) - 335.4127.

[0101] The code value 001 corresponds to the second type of Chirp signal, and the frequency of the Chirp signal varies with time as follows, for example: f(t) = sqrt(195.2030^2 - (t x 100 - 119.6983)^2) - 154.1964.

[0102] The code value 010 corresponds to the third type of Chirp signal, and the frequency of the Chirp signal varies with time as follows, for example: f(t) = sqrt(132.2852^2 - (t x 100 - 94.8707)^2) - 92.1895.

[0103] The code value 011 corresponds to the fourth type of Chirp signal, and the frequency of the Chirp signal varies with time as follows, for example: f(t) = sqrt(101.5348^2 - (t x 100 - 81.9567)^2) - 59.9367.

[0104] The code value 100 corresponds to the fifth type of Chirp signal, and the frequency of the Chirp signal varies with time as follows, for example: f(t) = sqrt(83.7061^2 - (t x 100 - 73.7851)^2) - 39.5281.

[0105] The code value 101 corresponds to the sixth type of Chirp signal, and the frequency of the Chirp signal varies with time as follows: f(t) = sqrt(72.4021^2 - (t x 100 - 67.9581)^2) - 24.9752.

[0106] Code value 110 corresponds to the 7th type of Chirp signal, the frequency of which varies with time as follows: f(t) = sqrt(64.9008^2 - (t x 100 - 63.4402)^2) - 13.6917.

[0107] Code value 111 corresponds to the 8th type of Chirp signal, the frequency of which varies with time as follows: f(t) = sqrt(59.8638^2 - (t x 100 - 59.7049)^2) - 4.3622.

[0108] The time-domain expression of the Chirp signal is: c(t) = real(exp(1j x 2 x pi x (f(t) x t)))

[0109] where j represents the imaginary unit, t represents time, and real() represents the real part.

[0110] Referring to FIG. 5, the frequency-time variation curves of the above-mentioned eight types of data Chirp signals according to an embodiment of the present disclosure are shown. FIG. 6 is a time-domain waveform diagram of the above-mentioned eight types of data Chirp signals according to an embodiment of the present disclosure, where the horizontal axis represents time (unit: s) and the vertical axis represents amplitude. As can be seen from FIG. 5, the frequency f varies with time t in a non-linear manner (for example, the function relationship between the frequency and time is not a first-order function relationship), and their waveforms are quite different from each other and do not overlap. In this case, the eight types of data Chirp signals can adopt the same frequency variation range, for example, the eight types of data Chirp signals are all in the variation range of 0-40 Hz. In addition, those skilled in the art can understand that one or two of the eight types of data Chirp signals shown in FIG. 5 can be replaced by a linear Chirp signal. In the case of using two linear Chirps, the slopes of their linear functions are opposite to each other.

[0111] In addition, those skilled in the art can understand that different correspondence relationships between the code values and the data Chirp signals can be adopted, for example, code value 000 can correspond to the 2nd type of Chirp signal or other types of Chirp signals.

[0112] Further, in the drilling data transmission, the preamble signal is crucial. The preamble signal is used to indicate the start and / or end of the transmitted data. This helps the receiving end to identify and parse the data signal faster, thereby improving the efficiency of data transmission. As mentioned earlier, the encoded signal includes the preamble signal and the data signal, the preamble signal is attached in front of the data signal, and there can be a certain time gap between them. In the prior art, a single Chirp signal is used as the preamble signal, which has low precision. In the case of large interference in the channel, the preamble signal may fail to be successfully identified, resulting in the loss of transmitted data. In the embodiments of the present disclosure, multiple different types of Chirp signals are combined as the preamble signal. In the embodiments of the present disclosure, the Chirp signals as the preamble signal are referred to as preamble Chirp signals, and these different types of preamble Chirp signals are different in terms of frequency transformation range and / or the relationship between frequency and time. Referring to FIG. 7, an encoded signal including a preamble signal and a data signal according to an embodiment of the present disclosure is shown.

[0113] In the embodiments of the present disclosure, four types of preamble Chirp signals are combined as the preamble signal, for example. The frequency and time relationship of the four types of preamble Chirp signals is shown as follows, for example.

[0114] The first type of preamble Chirp signal Chirp1 has a frequency-time relationship f(t) = 4xt.

[0115] The second type of preamble Chirp signal Chirp2 has a frequency-time relationship f(t) = 0.4x(10-t)2.

[0116] The third type of preamble Chirp signal Chirp3 has a frequency-time relationship f(t) = 0.4xt2.

[0117] The fourth type of preamble Chirp signal Chirp4 has a frequency-time relationship f(t) = 4x(10-t).

[0118] The transmission duration of the four types of preamble Chirp signals described above can be the same or different, since the transmission order of the preamble signals is known. Also, while the exemplary four types of preamble Chirp signals listed above include both linear and non-linear, one skilled in the art will appreciate that the plurality of different types of preamble Chirp signals used as preamble signals can all be linear or all be non-linear. In the case of all linear preamble Chirp signals, the different types of preamble Chirp signals can be distinguished by the range of frequency variation. In the case of all non-linear preamble Chirp signals, their range of frequency variation can or can not be the same. Further, the characteristics of the preamble Chirp signals are distinguished from the characteristics of the data Chirp signals as much as possible (e.g., in terms of range of frequency variation, relationship between frequency and time, and / or transmission duration) to prevent confusion. Generally, the transmission duration of each type of preamble Chirp signal can be greater than the transmission duration of the data Chirp signals, for example, in order to accurately identify the preamble signals through the autocorrelation of the Chirp signals. The advantage of having a short transmission duration for each data Chirp signal is that it allows for faster data transmission rates.

[0119] For the sake of convenience, the following description is provided with the range of frequency variation being 0-40 Hz, the transmission duration of each being 10 s, and the four relationships between frequency and time given above. However, one skilled in the art will appreciate that embodiments of the present disclosure are not limited thereto. Referring to FIGS. 8 and 9, FIG. 8 shows time domain waveform diagrams of the four types of preamble Chirp signals described above according to embodiments of the present disclosure, and FIG. 9 shows a time domain diagram of a preamble signal combining the four types of preamble Chirp signals described above according to embodiments of the present disclosure. As described above, the functional relationship between frequency and time for different types of preamble Chirp signals is not the same, and the four types of preamble Chirp signals described above include both linear Chirp signals and non-linear Chirp signals (e.g., the functional relationship between frequency and time is a non-linear function). Also, the transmission duration of each type of preamble Chirp signal is greater than the transmission duration of the data Chirp signals, for example, the transmission duration of each preamble Chirp signal is more than 5 times the transmission duration of each data Chirp signal. Alternatively, one skilled in the art will appreciate that the preamble Chirp signals are not limited to four, for example, they can be two, three, or even five.

[0120] After the encoding of the preamble signal and the data signal to form the encoded signal is completed, the drilling fluid pulse generator is controlled based on the encoded signal to generate a drilling fluid pressure wave pulse signal. The drilling fluid pressure wave pulse signal is transmitted in the drilling fluid to the surface. After the drilling fluid pressure wave pulse signal is obtained at the surface, the drilling fluid pressure wave pulse signal will be decoded to obtain the measured values of the parameters to be transmitted.

[0121] In the technical solution of the embodiments of the present disclosure, the preamble signal is constructed based on a plurality of preamble Chirp signal combinations, which effectively improves the signal synchronization accuracy, and / or the data Chirp signal corresponding to different code values is encoded in combination with the preset radix data signal converted from the downhole measurement data. Compared with the conventional single Chirp signal synchronization and sinusoidal wave signal data modulation, the reliability and applicability of data transmission in different drilling fluid channels are effectively improved.

[0122] Next, referring to FIG. 10, a flowchart of a method for decoding the drilling fluid pressure wave pulse signal according to an embodiment of the present disclosure is shown. The decoding method involved in FIG. 10 can be performed by the computer device 60 or other one or more processors shown in FIG. 1.

[0123] The method starts at step 1010, where the computer device obtains or receives the pressure wave pulse signal from, for example, a pressure sensor. Next, the method proceeds to step 1020, where the computer device removes interference noise in the pressure wave pulse signal using a filtering and / or equalization algorithm.

[0124] The filtering and / or equalization algorithm can remove most of the interference noise in the pressure wave pulse signal. The filtering and / or equalization algorithm can be selected from the noise removal and equalization algorithms in the prior art, and the present embodiment does not make a unique limitation on the noise removal and equalization algorithms.

[0125] The method proceeds to step 1030, where the reference preamble Chirp signal and the pressure wave pulse signal are cross-correlated to identify the preamble Chirp signal in the pressure wave pulse signal, and based on the preamble Chirp signal, the starting time position of the data signal in the pressure wave pulse signal is determined. The reference preamble Chirp signal refers to the various types of preamble Chirp signals that are not affected by noise and are used to form the preamble signal in the encoding process.

[0126] As mentioned above, during the encoding stage, multiple preamble chirp signals (e.g., four) are combined as a preamble signal. Accordingly, in the decoding method shown in Figure 10, multiple reference sub-preamble signals can be cross-correlated with the pressure wave pulse signal to determine the start time position of the data signal in the pressure wave pulse signal. The reference sub-preamble signals are constructed based on the preamble chirp signals used in the encoding stage and their corresponding order; each reference sub-preamble signal includes at least one reference preamble chirp signal. Taking the case of four preamble chirp signals combined as a preamble signal (named Chirp 1, Chirp 2, Chirp 3, and Chirp 4 respectively), the following ten reference sub-preamble signals can exist:

[0127] Chirp 1, Chirp 2, Chirp 3, Chirp 4, Chirp 1+Chirp 2, Chirp 2+Chirp 3, Chirp 3+Chirp 4, Chirp 1+Chirp 2+Chirp 3, Chirp 2+Chirp 3+Chirp 4, and Chirp 1+Chirp 2+Chirp 3+Chirp 4.

[0128] Specifically, step 1030 may include the following sub-steps: cross-correlating each reference sub-leader signal with the pressure wave pulse signal to obtain a correlation value; comparing the correlation value with a predetermined threshold; determining one or more start time positions based on one or more reference sub-leader signals whose correlation values ​​are greater than the predetermined threshold; and taking the median value of the one or more start time positions to determine the start time position of the data signal.

[0129] In this embodiment, by cross-correlation of different reference preamble signals and pressure wave pulse signals, and by taking the median of one or more determined start time positions to determine the start time position of the data signal, the signal synchronization accuracy can be significantly improved.

[0130] Figure 11 shows the cross-correlation results between different reference preamble signals and pressure wave pulse signals. n =xcorr(C n ,W)

[0131] In the formula, C n Let R be the nth reference preamble signal, W be the filtered pressure wave pulse signal, and R be the reference preamble signal. n The result is the nth cross-correlation processing result, and xcorr is the cross-correlation algorithm. By performing multiple cross-correlations and taking the median, the interference of secondary peaks on the main peak can be effectively avoided, thus improving synchronization accuracy.

[0132] Next, at step 1040, based on the starting time position of the data signal, time block division is performed according to the transmission duration T (e.g. 1s) of each data Chirp signal, to obtain a plurality of data signal time blocks. For details, refer to FIG. 12, which shows the division of a data signal into a plurality of data signal time blocks with a duration of T according to an embodiment of the present disclosure. The signal in each time block corresponds to a respective code value in the data signal.

[0133] The method proceeds to step 1050, and the reference data Chirp signal is cross-correlated with the pressure wave pulse signal in the time block of the data signal to determine the data Chirp signal corresponding to the waveform in the data signal time block, and then determine the code value represented by the time block of the data signal based on the corresponding data Chirp signal, i.e. decode the respective code value. The reference data Chirp signal refers to the respective type of data Chirp signal used to form the data signal in the encoding process without being affected by noise.

[0134] In some embodiments, cross-correlating the reference data Chirp signal with the pressure wave pulse signal in the time block of the data signal to determine the data Chirp signal corresponding to the waveform in the data signal time block comprises:

[0135] For each time block, each of the plurality of reference data Chirp signals is cross-correlated with the pressure wave pulse signal in the time block to obtain a correlation value.

[0136] The reference data Chirp signal with the largest correlation value is determined as the data Chirp signal corresponding to the waveform in the time block.

[0137] In the cross-correlation process, the larger the correlation value, the higher the correlation between the data Chirp signal and the pressure wave pulse signal in the current time block. Therefore, for each time block, the data Chirp signal with the highest correlation can be determined, and the code value corresponding to the data Chirp signal is determined as the decoding result of the pressure wave pulse signal in the current time block.

[0138] Then, at step 1060, based on the decoded code value, the measurement value of the downhole parameter is obtained. For example, the decoded code values are combined in front and back, and the measurement value of each parameter is divided based on the transmission order of the parameters. Thus, the decoding of the pressure wave pulse signal is completed.

[0139] In the embodiments of the present disclosure, the preamble signal is constructed based on a combination of multiple types of preamble Chirp signals, and the signal synchronization accuracy is improved by using multiple cross-correlations and taking the median value; the data Chirp signals corresponding to different code values are constructed, the signal coding is implemented on the preset radix data stream by using the preamble Chirp signal and the data Chirp signal, and the motor is controlled to move based on the coded signal to generate a pressure wave pulse signal, and further, the cross-correlation characteristics of different data Chirp signals are used for signal decoding. Compared with the traditional single Chirp signal synchronization and sinusoidal wave signal data stream modulation and demodulation, the reliability and applicability of data transmission in different drilling fluid channels are effectively improved.

[0140] Those skilled in the art can understand that the order of the method steps in the above embodiments of the present disclosure does not necessarily follow the order shown in the drawings, and even some steps can be performed simultaneously, or some steps can be removed, combined, as long as they do not conflict with the technical problems to be solved by the technical scheme of the present disclosure.

[0141] In order to reflect the superiority of the technical scheme of the present disclosure over the prior art, the encoding and decoding results of Chirp signals and sinusoidal wave signals after attenuation through the drilling fluid channel are further compared. FIG. 13 shows the attenuation characteristics of the drilling fluid channel, and it can be seen that the drilling fluid channel has obvious frequency-selective attenuation characteristics, and there is an obvious attenuation stopband at about 18 Hz. FIG. 14 shows the time-domain waveforms of 8 sinusoidal wave signals of different frequencies (labeled as Sin 1 to Sin 8 from top to bottom) after channel attenuation, which are used to correspond to 8 binary code values 000 to 111 respectively. After channel attenuation, the amplitudes of sinusoidal wave signals of different frequencies have large differences. The amplitudes of Sin4 and Sin5 signals are only about 40% of those of other signals. When the filtered waveform in a certain time block corresponds to the code value 011 (for example, Sin 4), the cross-correlation processing is performed on it by using sinusoidal wave signals of different frequencies, and the result is shown in FIG. 15. It can be observed that the amplitudes (i.e., correlation values) of the cross-correlation processing results of different sinusoidal wave signals have little difference, and the amplitude (i.e., correlation value) of the cross-correlation processing result of the Sin4 signal is not the largest, which will lead to decoding failure.

[0142] Figure 16 shows the time-domain waveforms of different Chirp signals, Chirp 1 to Chirp 8, after channel attenuation. After channel attenuation, the amplitudes of different types of Chirp signals do not differ greatly. The amplitudes of Chirp 4 and Chirp 5 signals are about 80% of those of other signals. When the filtered signal in a time block corresponds to the code value 011 (corresponding to Chirp 4), the cross-correlation processing is performed using different types of reference Chirp signals, and the results are shown in Figure 17. It can be seen that the amplitude of the cross-correlation processing result of Chirp 4 signal is obviously greater than the amplitudes of the cross-correlation processing results of other Chirp signals, and thus the decoding is successful.

[0143] In addition, referring to Figures 18 and 19, Figure 18 shows the preamble signal after channel attenuation and noise interference according to an embodiment of the present disclosure, and Figure 19 shows the cross-correlation result of the preamble signal after channel attenuation and noise interference according to an embodiment of the present disclosure. Apparently, the synchronization result of the sub-preamble Chirp 4 signal deviates obviously, while the synchronization results of other sub-preamble signals are better. If the prior art solution only uses Chirp 4 signal for single cross-correlation, synchronization cannot be achieved; the technical solution of the present disclosure uses Chirp signals for multiple cross-correlation to obtain a median value, which can effectively avoid error data, and thus determine the position of the data signal.

[0144] Next, referring to Figure 20, a controller 2000 according to an embodiment of the present disclosure is shown, which can be the controller 20 or the computer device 60 shown in Figure 1, or some combination thereof. The controller includes a processor 2001, a memory 2002, and an interface 2003. The processor 2001 implements the encoding or decoding operations by executing computer-executable instructions that define the methods shown in Figures 2 and 10. A computer program product including the computer-executable instructions can be stored in the memory 702. The methods described in Figures 2 and 10 can be defined by the computer-executable instructions included in the computer program product stored in the memory 2002 and executed by the processor 2001 executing the computer-executable instructions. The interface 2003 can include a network interface for communicating with other devices via a network, and can also include other input / output devices (e.g., a display, a keyboard, a mouse, a speaker, a button, a touchpad, a touchscreen, etc.) that enable a user to interact with the controller 2000. Those skilled in the art will recognize that an implementation of a practical control system can also contain other components and that Figure 20 is a high-level representation of some of the components of such a control system for illustrative purposes.

[0145] Memory 2002 includes tangible, non-transitory machine-readable storage media, and can also include high-speed random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDR RAM), or other random access solid state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory devices, semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), digital versatile disc read-only memory (DVD-ROM) disks, or other non-volatile solid state storage devices.

[0146] It is recognized that certain features of the disclosure described in the context of separate embodiments can also be provided in combination in a single embodiment. Conversely, various features of the disclosure described in the context of a single embodiment can also be provided separately or in any appropriate

[0147] Although the present disclosure has been described in connection with certain specific embodiments, it is to be understood that the disclosure is not limited to the specific embodiments disclosed. Rather, it is intended to cover any alternatives, modifications, and equivalents as can be included within the spirit and scope of the disclosure as defined by the appended claims.

[0148] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. In addition, no admission is made that any reference constitutes prior art. The combination of multiple steps, processes, or methods disclosed in this specification can not be necessary to practice the disclosure, particularly since the combination can not be enabled or can not specific to the disclosure. The title of this document includes a claim which can not be necessary to practice the disclosure.

Claims

1. A method for encoding drilling fluid pulse data, comprising: obtaining data values in a preset radix, the data values representing measured values of drilling parameters; segmenting the data values into code values of a fixed number of bits; and based on the code values, selecting a type of data Chirp signal corresponding to a code value from a plurality of different types of data Chirp signals to encode the code value to obtain a data signal. 2.The method of claim 1, wherein the plurality of different types of data Chirp signals are different from each other in terms of functional relationship between frequency and time, and the number of the plurality of different types of data Chirp signals is equal to the number of different values represented by the code values of the fixed number of bits. 3.The method of claim 2, wherein the plurality of different types of data Chirp signals have the same duration. 4.The method of claim 3, wherein the plurality of different types of data Chirp signals have the same range of frequency variation, and include non-linear data Chirp signals; or the plurality of different types of data Chirp signals have different ranges of frequency variation, and include linear and / or non-linear data Chirp signals. 5.The method of claim 4, wherein wherein the functional relationship between frequency and time of the non-linear data Chirp signal is a non-linear function. 6.The method of claim 3, wherein the following equation is satisfied among the drilling fluid pulse data transmission rate, the number of the plurality of different types of data Chirp signals, and the duration: B=log2(N) / T wherein B represents the drilling fluid pulse data transmission rate, N represents the number of the data Chirp signals, and T represents the duration of the data Chirp signal. 7.The method of claim 2, further comprising: attaching a preamble signal in front of the data signal to form encoded data, the preamble signal being used to indicate at least the start position of the data signal, wherein the preamble signal includes a plurality of different types of preamble Chirp signals. 8.The method of claim 7, wherein the plurality of different types of preamble Chirp signals are different from each other in terms of functional relationship between frequency and time. 9.The method of claim 7, wherein the preamble Chirp signals satisfy at least one of the following: the plurality of different types of preamble Chirp signals have different durations; the plurality of different types of preamble Chirp signals have different ranges of frequency variation, and include linear and / or non-linear preamble Chirp signals; or the plurality of different types of preamble Chirp signals have the same range of frequency variation, and include or non-linear preamble Chirp signals. 10.The method of claim 7, wherein the plurality of different types of preamble Chirp signals have a duration greater than the duration of the data Chirp signals. ​ 11. The method of claim 8, wherein a functional relationship between frequency and time of the preamble Chirp signal is different from a functional relationship between frequency and time of the data Chirp signal.

12. The method of any one of claims 1-11, wherein the data values are binary data values, the code values are binary code values, and the fixed number of bits is greater than or equal to 2.

13. A method of decoding drilling fluid pulse data, comprising: receiving a pressure wave pulse signal, wherein the pressure wave pulse signal includes a pressure wave pulse signal representing a data signal, wherein the data signal represents a measured value of a drilling parameter and is formed by different types of data Chirp signals; determining a start time position of the data signal representing the value of the drilling parameter in the pressure wave pulse signal; based on the start time position of the data signal, dividing the pressure wave pulse signal corresponding to the data signal into time blocks according to a transmission duration of each data Chirp signal; cross-correlating a plurality of reference data Chirp signals of different types with the pressure wave pulse signal in the time blocks to determine the data Chirp signal corresponding to the pressure wave pulse signal in the time block of the data signal; and based on the corresponding data Chirp signal, determining a code value represented by the time block of the data signal.

14. The method of claim 13, wherein the pressure wave pulse signal further includes a pressure wave pulse signal representing a preamble signal, the preamble signal indicating at least a start position of the data signal and being composed of a plurality of preamble Chirp signals of different types, wherein determining the start time position of the data signal representing the value of the drilling parameter in the pressure wave pulse signal comprises: cross-correlating a plurality of reference sub-preamble signals with the pressure wave pulse signal respectively to obtain correlation values; comparing the correlation values with a predetermined threshold; based on one or more reference sub-preamble signals having a correlation value greater than the predetermined threshold, determining one or more start time positions; and determining a median value of the one or more start time positions to determine the start time position of the data signal, wherein the reference sub-preamble signals are constructed based on the preamble Chirp signals employed in the encoding stage and an order of the corresponding preamble Chirp signals.

15. The method of claim 13, wherein cross-correlating a plurality of reference data Chirp signals of different types with the pressure wave pulse signal in the time blocks to determine the data Chirp signal corresponding to the pressure wave pulse signal in the time block of the data signal comprises: for each time block, cross-correlating each of the plurality of reference data Chirp signals of different types with the pressure wave pulse signal in the time block to obtain a correlation value; and determining the reference data Chirp signal having the largest correlation value as the data Chirp signal corresponding to the waveform in the time block, wherein the reference data Chirp signals of different types are the data Chirp signals of respective types used to form the data signal in the encoding process.

16. The method of claim 13, further comprising: ​ ​ filtering and / or equalizing the pressure wave pulse signal to remove interfering noise in the pressure wave pulse signal.

17. The method of any one of claims 13-16, wherein the code value is a binary code value, and a number of bits of the code value is greater than or equal to 2.

18. A drilling fluid pulse encoding device, comprising: a controller, and a drilling fluid pulse generator, wherein the controller is configured to perform the method of any one of claims 1-12 to obtain encoded data, and control the drilling fluid pulse generator to generate a pressure wave pulse signal based on the encoded data.

19. A drilling fluid pulse decoding device, comprising: a computing device, and a pressure sensor, the computing device is configured to receive a pressure wave pulse signal from the pressure sensor, and perform the method of any one of claims 13-17.

20. A controller, comprising: one or more processors, and a computer-readable storage medium comprising executable instructions stored thereon that, when executed by the one or more processors, implement the method of any one of claims 1-17.

21. A machine-readable storage medium comprising executable instructions stored thereon that, when executed by one or more processors, implement the method of any one of claims 1-17.

22. A computer program product comprising executable instructions that, when executed by one or more processors, implement the method of any one of claims 1-17.

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