A decoding device and method for transmitting a pulse signal while drilling

Abstract

The application provides a decoding device and method for transmitting a pulse signal while drilling, which comprises a pulse signal collecting mechanism and a signal processing mechanism, wherein the pulse signal collecting mechanism is composed of a signal sensing module and a pressure wave collecting module; the signal sensing module acquires a mud pulse pressure signal processed by coding from downhole and converts the mud pulse pressure signal into a corresponding electrical signal; the pressure wave collecting module collects the mud pulse electrical signal and converts the mud pulse electrical signal into a corresponding digital signal; then the signal processing mechanism receives the mud pulse digital signal and performs a denoising decoding operation based on an optimized variational mode decomposition and a cross-correlation algorithm to acquire downhole measurement data; the device can overcome the problems of poor mud pulse signal synchronization accuracy and high bit error rate in the existing decoding technology, can adaptively remove the influence of interference noise based on the optimized variational mode decomposition and the cross-correlation algorithm, is suitable for various drilling measurement conditions, has high practicability, and effectively improves the quality of the data transmitted while drilling by using a simple structure.

Description

Technical Field

[0001] This invention relates to the field of measurement while drilling (MSD) engineering technology in oil and gas exploration and development, and particularly to a decoding device and method for transmitting pulse signals while drilling. Background Technology

[0002] Driven by the exploration and development needs of oil and gas companies, directional drilling technology has developed rapidly. During drilling, especially in complex well structures such as horizontal wells, extended reach wells, and branch wells, well site personnel need to monitor various downhole parameters in real time, leading to the development of Measurement While Drilling (MWD) technology. Mud pulse transmission is currently the most widely used method for transmitting data while drilling. Its basic principle is to change the mud pressure in the drill string using a downhole pulse generator, forming pressure waves that transmit measurement data to the surface in the form of pulses. This transmission method has advantages such as lower requirements for equipment and operation, and strong adaptability to wellbore and formation conditions.

[0003] However, when pulse signals propagate in drilling fluid, they are inevitably interfered with by various noise sources such as well site voltage, surface mud pumps, bottom hole power machinery, air bubbles in the drilling fluid, and moving drill tools. It is usually impossible to directly identify useful pulse signals from the waveform received from the surface. Furthermore, to enhance anti-interference capabilities, downhole control systems typically convert measurement data into pressure wave signals suitable for pulse generator generation and long-distance transmission according to certain encoding rules. Therefore, the waveform received from the surface must be decoded to obtain the true downhole measurement data. Currently, the conventional mud pulse signal processing flow involves denoising the original signal using methods such as median filtering, FIR digital filtering, and wavelet transform, and then obtaining the location of useful pulses through peak-finding algorithms. These algorithms generally achieve good application results in shallow and medium-depth drilling environments, but their parameter settings rely on manual configuration. With increasing depth, the amplitude attenuation of the mud pulse signal intensifies. Additionally, as the wellbore size decreases, mud pressure loss increases and displacement decreases, which also significantly weakens the amplitude of the mud pulse signal. Therefore, in ultra-deep or small-bore drilling environments, conventional algorithms suffer from poor noise reduction and limited adaptability, which leads to unreliable data acquisition and fails to meet the requirements of measurement while drilling in exploration and development projects.

[0004] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] To address the above problems, the present invention provides a decoding device for transmitting pulse signals while drilling. In one embodiment, the device includes: The pulse signal acquisition mechanism consists of a signal sensing module and a pressure wave acquisition module. The signal sensing module uses a pressure sensor and is configured to continuously acquire mud pulse pressure signals from downhole encoded processing and convert them into mud pulse electrical signals. The mud pulse pressure signals are encoded using pulse position modulation. The pressure wave acquisition module is configured to continuously acquire mud pulse electrical signals from the signal sensing module and convert them into mud pulse digital signals. The signal processing mechanism is connected to the pressure wave acquisition module of the pulse signal acquisition mechanism. It receives the mud pulse digital signal from the pressure wave acquisition module and performs denoising and decoding operations based on the optimized variational mode decomposition and cross-correlation algorithm to obtain the downhole measurement data represented by the mud pulse signal.

[0006] Preferably, in one embodiment, the pressure wave acquisition module includes: An isolated safety barrier module, which is connected to a signal sensing module, is configured to process the mud pulse electrical signal from the signal sensing module into a stable mud pulse voltage signal. The data acquisition card module is connected to the isolated safety barrier module and is configured to acquire the mud pulse voltage signal of the isolated safety barrier module and then convert it into the corresponding mud pulse digital signal. The ground-based regulated power supply module, integrated with the isolated safety barrier module and the data acquisition card module, is installed on the ground at the site and configured to connect to the power grid to provide stable power to the signal sensing module and the isolated safety barrier module.

[0007] As a further improvement of the present invention, the signal processing mechanism includes an optimization decomposition module, which uses a combination of particle swarm optimization algorithm and variational mode decomposition algorithm to realize the optimized variational mode decomposition of mud pulse signal.

[0008] Furthermore, in one embodiment, the optimization decomposition module includes: The decomposition parameter initialization unit is configured to construct a suitability function and set the optimization range of the penalty factor α and the number of decompositions K. The optimization evolution unit evaluates the appropriate function value of each particle and determines whether each particle meets the population evolution stopping condition. If it does not meet the condition, it continues to optimize until the maximum population evolution preset value is met. The signal decomposition unit performs VMD decomposition on the original mud pulse signal using the obtained optimal parameters to obtain the intrinsic mode components of the signal. The classification and denoising unit divides the intrinsic mode components into random noise signal, pump noise signal, baseline signal, unresolved signal and useful signal in sequence according to the spectral characteristics of each intrinsic mode component. The useful signal mode components are superimposed to obtain the denoised waveform.

[0009] Specifically, in one embodiment, the classification and denoising unit performs classification according to the following operations: Signals with a peak width greater than the first reference value are classified as random noise signals; signals with a peak position less than an integer multiple of the pump-driven fundamental frequency are classified as pump-driven noise signals; signals with a peak position less than the zero frequency are classified as baseline signals; signals with a peak position greater than the zero frequency are classified as undecomposed noise signals; and signals whose frequency range satisfies the condition that the peak position is greater than 0.5 / PW are classified as undecomposed noise signals. Signals that do not meet any of the above conditions are useful signals.

[0010] On the other hand, in one embodiment, the signal processing mechanism further includes a cross-correlation operation module, which is configured to construct a synchronization head correlator and a data block correlator respectively, and perform cross-correlation operations between the denoised waveform of the signal from the optimization decomposition module and the synchronization head correlator and the data block correlator respectively to determine the starting position of the target decoded mud pulse signal and the information within the data block.

[0011] Furthermore, in one embodiment, the cross-correlation operation module is configured to perform cross-correlation processing on the waveform after signal denoising and the synchronization head correlator, and obtain the position corresponding to the maximum value of the correlated waveform as the starting position of the mud pulse signal.

[0012] In an optional embodiment, the cross-correlation operation module is configured to construct a data block correlator representing hexadecimal numbers 0x0 to 0xF, perform cross-correlation processing between the denoised waveform and each data block correlator, and obtain the hexadecimal number corresponding to the maximum correlation value, which is the hexadecimal number represented by the waveform in that data block.

[0013] Based on the application aspects of the apparatus described in any one or more of the above embodiments, the present invention also provides a method for decoding transmission-while-drilling pulse signals, which is applied to the apparatus described in any one or more of the above embodiments, and the method includes: Using a signal sensing module installed on the ground, mud pulse pressure signals after downhole encoding are continuously acquired and converted into mud pulse electrical signals; the mud pulse pressure signals are encoded using pulse position modulation. The pressure wave acquisition module continuously acquires mud pulse electrical signals from the signal sensing module, converts them into mud pulse digital signals, and transmits them to the signal processing mechanism. The downhole measurement data represented by the mud pulse signal is obtained by performing noise reduction and decoding operations based on optimized variational mode decomposition and cross-correlation algorithms by the signal processing mechanism.

[0014] Based on other aspects of the methods described in the above embodiments, the present invention also provides a storage medium storing program code that can implement the methods as described in any one or more of the above embodiments.

[0015] Compared with the closest prior art, the present invention also has the following beneficial effects: This invention provides a decoding device for transmission-while-drilling pulse signals. The device consists of a signal sensing module that acquires mud pulse pressure signals from downhole and converts them into corresponding electrical signals; a pressure wave acquisition module that acquires mud pulse electrical signals and converts them into corresponding digital signals; and a signal processing mechanism that receives the mud pulse digital signals and performs denoising and decoding operations based on optimized variational mode decomposition and cross-correlation algorithms to acquire downhole measurement data. The device has a reasonable structure, is easy to manufacture, and has strong adaptability. Based on optimized variational mode decomposition and cross-correlation algorithms, this invention can adaptively remove the influence of interference noise and is applicable to drilling measurement conditions with low signal-to-noise ratio. It effectively controls the probability of poor signal decoding synchronization accuracy and high bit error rate in different drilling measurement conditions. In addition, the present invention sets up a ground pressure wave acquisition module between the signal sensing module and the signal processing mechanism, which effectively improves the explosion-proof capability, anti-interference capability and stability of the overall device.

[0016] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description and the drawings. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of a decoding device for transmitting pulse signals while drilling provided in an embodiment of the present invention; Figure 2 This is an example diagram of the pulse position modulation coding rule used in one embodiment of the present invention; Figure 3 This is a flowchart illustrating the principle of signal decoding in the decoding device for transmitting pulse signals while drilling, provided in another embodiment of the present invention. Figure 4(a) is an example diagram of the theoretical synchronization head correlator used in the decoding device for transmitting pulse signals while drilling in one embodiment of the present invention; Figure 4 (b) is an example diagram of the theoretical synchronization head waveform used in the decoding device for transmitting pulse signals while drilling in one embodiment of the present invention; Figure 4 (c) is an example waveform diagram of the theoretical synchronization head waveform and the waveform after cross-correlation processing by the correlator used by the decoding device for transmitting pulse signals while drilling in this embodiment of the invention; Figure 5 (a) is an example diagram of the theoretical data block correlator used in the decoding device for transmitting pulse signals while drilling in one embodiment of the present invention; Figure 5 (b) is an example waveform diagram of the theoretical data block (0X9) used by the decoding device for transmitting pulse signals while drilling in one embodiment of the present invention; Figure 5 (c) is a correlation curve of the theoretical data block waveform and the correlation value after cross-correlation processing by the correlator used by the decoding device for transmitting pulse signals while drilling in this embodiment of the invention; Figure 6 This is a flowchart illustrating the decoding method for transmission-while-drilling pulse signals provided in another embodiment of the present invention; Figure descriptions: 10: Signal sensing module, 20: Pressure wave acquisition module, 30: Signal processing mechanism, 21: Regulated power supply module, 22: Isolated safety barrier module, 23: Acquisition card module. Detailed Implementation

[0018] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Those skilled in the art will then fully understand how the present invention uses technical means to solve technical problems and achieve technical effects, and will be able to implement the present invention specifically based on the above-described implementation process. It should be noted that, as long as there is no conflict, the various embodiments and features of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0019] Although the flowchart describes the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can terminate when its operation is complete, but it may also have additional steps not included in the diagram. A process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0020] Computer equipment includes user equipment and network equipment. User equipment or clients include, but are not limited to, computers, smartphones, PDAs, etc.; network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing consisting of a large number of computers or network servers. Computer equipment can operate independently to implement this invention, or it can connect to a network and implement this invention through interaction with other computer equipment in the network. The network in which the computer equipment is located includes, but is not limited to, the Internet, wide area network, metropolitan area network, local area network, VPN network, etc.

[0021] The terms “first,” “second,” etc., may be used herein to describe various units, but these units should not be limited by these terms; they are used merely to distinguish one unit from another. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. When a unit is referred to as “connected” or “coupled” to another unit, it may be directly connected or coupled to said other unit, or there may be intermediate units present.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0023] During drilling, especially in complex well structures such as horizontal wells, extended reach wells, and branch wells, well site personnel need to monitor various downhole parameters in real time. Measurement While Drilling (MWD) technology has emerged to address this need. Mud pulse transmission is currently the most widely used MWD data transmission method. Its basic principle is to change the mud pressure in the drill string using a downhole pulse generator, forming pressure waves that transmit measurement data to the surface in the form of pulses. This transmission method has advantages such as lower requirements for equipment and operation, and strong adaptability to wellbore and formation conditions.

[0024] However, when pulse signals propagate in drilling fluid, they are inevitably interfered with by various noise sources such as well site voltage, surface mud pumps, bottom hole power machinery, air bubbles in the drilling fluid, and moving drill tools. It is usually impossible to directly identify useful pulse signals from the waveform received from the surface. Furthermore, to enhance anti-interference capabilities, downhole control systems typically convert measurement data into pressure wave signals suitable for pulse generator generation and long-distance transmission according to certain encoding rules. Therefore, the waveform received from the surface must be decoded to obtain the true downhole measurement data. Currently, the conventional mud pulse signal processing flow involves denoising the original signal using methods such as median filtering, FIR digital filtering, and wavelet transform, and then obtaining the location of useful pulses through peak-finding algorithms. These algorithms generally achieve good application results in shallow and medium-depth drilling environments, but their parameter settings rely on manual configuration. With increasing depth, the amplitude attenuation of the mud pulse signal intensifies. Additionally, as the wellbore size decreases, mud pressure loss increases and displacement decreases, which also significantly weakens the amplitude of the mud pulse signal. Therefore, in ultra-deep or small-bore drilling environments, conventional algorithms suffer from poor noise reduction and limited adaptability, which leads to unreliable data acquisition and fails to meet the requirements of measurement while drilling in exploration and development projects.

[0025] During the drilling process, the device provided by this invention can collect and process mud pulse signals on the ground, thereby obtaining parameters such as well inclination, azimuth, and tool face in real time for reference by on-site engineers, and has a promising application prospect.

[0026] To address the aforementioned shortcomings of existing technologies, this invention provides a decoding device and method for drilling pulse signals. Compared to existing decoding methods, this method, based on optimized variational mode decomposition and cross-correlation algorithms, can adaptively remove the influence of interference noise and improve the decoding success rate of mud pulse signals.

[0027] The following describes the structural design and operating principle of the device in the embodiments of the present invention in detail with reference to the accompanying drawings. Although the logical order of each operation is shown in the principle description, in some cases, the operations shown or described may be performed in a different order than that shown here.

[0028] Example 1 Figure 1 A schematic diagram of a decoding device for transmission-while-drilling pulse signals according to an embodiment of the present invention is shown. (Refer to...) Figure 1It is known that the device is installed in the ground area and includes: a pulse signal acquisition mechanism, which consists of a signal sensing module 10 and a pressure wave acquisition module 20; the signal sensing module uses a pressure sensor, is installed at the riser, and is configured to continuously acquire the mud pulse pressure signal after downhole encoding and processing, and convert it into a mud pulse electrical signal; the mud pulse pressure signal is encoded using a pulse position modulation method; The pressure wave acquisition module is configured to continuously acquire mud pulse electrical signals from the signal sensing module 10 and convert them into mud pulse digital signals. The signal processing unit 30 is connected to the pressure wave acquisition module 20 of the pulse signal acquisition unit. It receives the mud pulse digital signal from the pressure wave acquisition module 20 and performs denoising and decoding operations based on the optimized variational mode decomposition and cross-correlation algorithm to obtain the downhole measurement data represented by the mud pulse signal.

[0029] Furthermore, in one embodiment, the pressure wave acquisition module includes: The isolated safety barrier module 22 is connected to the signal sensing module 10 and is configured to process the mud pulse electrical signal from the signal sensing module 10 into a stable mud pulse voltage signal. The acquisition card module 23 is connected to the isolated safety barrier module 22 and is configured to acquire the mud pulse voltage signal of the isolated safety barrier module 22 and then convert it into the corresponding mud pulse digital signal. The ground-based voltage regulator module 21, which is integrated with the isolated safety barrier module 22 and the data acquisition card module 23, is installed on the ground, such as in a ground acquisition box, and is configured to connect to the power grid to provide stable power to the signal sensing module 10 and the isolated safety barrier module 22.

[0030] The aforementioned device, used for surface decoding of mud pulse signals, can adaptively remove the influence of interference noise based on optimized variational mode decomposition and cross-correlation algorithms. This overcomes the problems of poor synchronization accuracy and high bit error rate in the decoding process of mud pulse signals under low signal-to-noise ratio conditions. The device has a reasonable structure, is easy to manufacture, and is highly adaptable, effectively improving the decoding performance of data transmitted while drilling.

[0031] Furthermore, in a practical application embodiment, the function of the voltage regulator module 21 is to convert AC 220V voltage to DC 5V voltage; the function of the isolated safety barrier module 22 is to improve the system's explosion-proof capability, anti-interference capability, and stability. The function of the data acquisition card module 23 is to convert the actual measured analog signal into a digital signal that can be recognized by a computer. The connection structure is typically set as follows: the signal sensing module 10 is connected to the isolated safety barrier module 22, which is connected to the data acquisition card module 23, which is connected to the signal processing mechanism 30. The voltage regulator module 21 is connected to the isolated safety barrier module 22 and supplies power to both the isolated safety barrier module 22 and the signal sensing module 10. The signal processing mechanism 30 supplies power to the data acquisition card module 23. In an optional embodiment, the signal sensing module can be a pressure sensor, and the signal processing mechanism can be a computer system.

[0032] In this invention, an isolated safety barrier is used. On the one hand, it converts the mud pulse current signal into a mud pulse voltage signal. In actual applications, the input range is 4-20mA and the output range is 1-5V. On the other hand, because the isolated safety barrier adopts measures such as voltage limiting, current limiting, and isolation, it can not only prevent dangerous energy from entering the hazardous site from the intrinsically safe terminal, thus improving the intrinsically safe explosion-proof performance of the system, but also increase the anti-interference capability of the system and greatly improve the reliability of the system operation.

[0033] In practical applications, the regulated power supply module 21, the isolated safety barrier module 22, and the data acquisition card module 23 can typically be integrated into a ground-based data acquisition box in a designated area on-site. When signal decoding is required, i.e., when the signal sensing module 10 of the pulse signal acquisition mechanism acquires a valid mud pulse pressure signal, the pressure wave acquisition module 20 converts the mud pulse electrical signal into a mud pulse digital signal and transmits it to the signal processing mechanism 30. More specifically, the signal sensing module 10 converts the mud pulse pressure signal into a mud pulse current signal, the isolated safety barrier module 22 converts the mud pulse current signal into a mud pulse voltage signal, and the data acquisition card module 23 converts the mud pulse voltage signal into a mud pulse digital signal.

[0034] Figure 2 This diagram illustrates an example of the pulse position modulation (PPM) coding rule used in one embodiment of the present invention. PPM coding is a coding method that uses time intervals as data streams to transmit information. Typically, one pulse represents one hexadecimal number (0x0~0xF), the specific number depending on its position. When the start pulse is set to the preceding synchronization header pulse, the data block length is usually kept constant, and each data block contains only one pulse, so the time taken to transmit data does not change with the size of the transmitted data. In PPM coding, all pulses have the same width.

[0035] In practical applications, encoding rules can be customized according to the signal acquisition requirements downhole, mainly including: (1) The pulse reference position is the midpoint of the pulse; (2) The starting pulse is the preceding synchronization head pulse; (3) The minimum pulse recovery time with at least two pulse widths starting from the previous pulse position; (4) A frame of data consists of three parts: a synchronization header, a sequence number, and downhole measurement data. The first three pulses have two fixed time intervals, which can be used to determine whether it is a synchronization header; the interval between the third and fourth pulses represents the sequence number of the data set. Starting from the third pulse, a data block with a fixed time length is divided, and the time interval between each pulse and the start line of the data block represents the hexadecimal value represented by the pulse. (5) The encoding order is low bit first, high bit last.

[0036] Figure 3 A flowchart illustrating the principle of signal decoding in a decoding device for transmission-while-drilling pulse signals according to another embodiment of the present invention is shown, as follows. Figure 3 As shown, in one embodiment, the principle of the signal processing mechanism of the present invention for decoding during drilling involves Particle Swarm Optimization (PSO), Variational Mode Decomposition (VMD), and cross-correlation algorithms. The signal processing mechanism 30 includes an optimization decomposition module, which uses a combination of PSO and VMD to achieve optimized variational mode decomposition of the mud pulse signal.

[0037] Among them, the particle swarm optimization algorithm can be used to optimize the penalty factor α and the number of decompositions K in the VMD algorithm; the VMD algorithm can be used to decompose the original signal and remove interference noise; and the cross-correlation algorithm can be used to identify the denoised signal.

[0038] Specifically, in one embodiment, the optimization decomposition module includes: The decomposition parameter initialization unit is configured to construct a suitability function, initialize various parameters of PSO, and set the optimization range of the penalty factor α and the number of decompositions K. The optimization evolution unit evaluates the appropriate function value of each particle and determines whether each particle meets the population evolution stopping condition. If it does not meet the condition, it continues to optimize until the maximum population evolution preset value is met. The signal decomposition unit performs VMD decomposition on the original mud pulse signal using the obtained optimal parameters to obtain the intrinsic mode components of the signal. The classification and denoising unit divides the intrinsic mode components into random noise signal, pump noise signal, baseline signal, unresolved signal and useful signal in sequence according to the spectral characteristics of each intrinsic mode component. The useful signal mode components are superimposed to obtain the denoised waveform.

[0039] In an optional embodiment, the decomposition parameter initialization unit sets the appropriate function to the ratio of the root mean square error of the original signal and the denoised signal (reconstructed signal) to the cross-correlation coefficient of the original signal and the denoised signal (reconstructed signal). The optimization range of K and α is determined based on empirical knowledge and does not need to be adjusted according to well conditions. It is usually set to K∈[2,10] and α∈[100,5000].

[0040] Based on the spectral characteristics of each intrinsic mode component, during the classification process, random noise signals are characterized by a wide frequency distribution; pump noise signals have significant energy maxima near integer multiples of the pump fundamental frequency; baseline signals have energy mainly concentrated in low frequencies below 0.1Hz; and useful signals have energy mainly concentrated around 0.5 / PW, where PW is the pulse width of the excitation signal. Therefore, signals with a full frequency distribution and energy differences between frequencies less than a set value are classified as random noise signals; signals with energy maxima satisfying a set requirement near integer multiples of the pump fundamental frequency are classified as pump noise signals; signals with a concentrated proportion of spectral characteristics at low frequencies below 0.1Hz satisfying a set value are classified as baseline signals, and the rest are useful signals. In a specific embodiment, the classification and denoising unit performs the classification as follows: Signals with a peak width greater than the first reference value are classified as random noise signals; signals with a peak position less than an integer multiple of the pump's fundamental frequency are classified as pump noise signals; signals with a peak position less than the zero frequency are classified as baseline signals; and signals with other spectral ranges where the peak position is greater than 0.5 / PW is classified as unresolved noise signals. Signals that do not meet any of these conditions are considered useful signals. These reference values ​​are determined empirically and do not require adjustment based on well conditions. Typically, the first reference value is set to 1 / PW, the second to 1 / PW, the third to 0.1Hz, and the fourth to 0.5 / PW.

[0041] This invention improves the decoding success rate of mud pulse signals by adaptively removing the influence of interference noise based on optimized variational mode decomposition and cross-correlation algorithms. Therefore, in a preferred embodiment, the signal processing mechanism further includes a cross-correlation operation module, which is configured to construct a synchronization head correlator and a data block correlator respectively, and perform cross-correlation operations between the denoised waveform of the signal from the optimized decomposition module and the synchronization head correlator and the data block correlator respectively to determine the starting position of the target decoded mud pulse signal and the information within the data block.

[0042] The cross-correlation function satisfies the logic described in the following formula:

[0043] In the formula, r xy For relevant values, x ( t () represents the signal to be correlated. y ( t ) is the synchronization head correlator.

[0044] Furthermore, in one embodiment, the cross-correlation operation module is configured to perform cross-correlation processing on the waveform after signal denoising and the synchronization head correlator, and obtain the position corresponding to the maximum value of the correlated waveform as the starting position of the mud pulse signal; Specifically, in one embodiment, the cross-correlation operation module is configured to construct a data block correlator representing hexadecimal numbers 0x0~0xF, perform cross-correlation processing between the denoised waveform and each data block correlator, and obtain the hexadecimal number corresponding to the maximum correlation value, which is the hexadecimal number represented by the waveform in that data block.

[0045] The cross-correlation function satisfies the logic described in the following formula:

[0046] In the formula, r xy For relevant values, x ( t () represents the signal to be correlated. y ( t ) is the data block correlator.

[0047] Figure 4 The diagram shows the waveforms before and after cross-correlation processing between a theoretical synchronization head waveform and a synchronization head correlator. Among them, Figure 4 (a) is an example diagram of the theoretical synchronization head correlator used; Figure 4 (b) is an example diagram of the theoretical synchronization header waveform before cross-correlation processing; Figure 4(c) is an example waveform of the theoretical synchronization head waveform after cross-correlation processing with the correlator; as can be seen from the information in the figure, the position corresponding to the maximum value of the waveform after correlation processing is 0, which is completely consistent with the starting position of the theoretical synchronization head.

[0048] Figure 5 The diagram shows the correlation curves of a theoretical data block (0X9) waveform and the correlation values ​​of each data block after cross-correlation processing by correlators. Figure 5 (a) is an example diagram of the theoretical data block correlator used; Figure 5 (b) is an example waveform of the theoretical data block (0X9) before cross-correlation processing; Figure 5 (c) is a curve showing the correlation value between the waveform of the theoretical data block and the correlation value after cross-correlation processing by the correlator. According to the information in the figure, the hexadecimal number corresponding to the maximum correlation value after cross-correlation processing is 0X9, which is completely consistent with the hexadecimal number represented by the theoretical data block, indicating the reliability and applicability of the above cross-correlation processing method.

[0049] The drilling transmission pulse signal decoding device provided in this embodiment of the invention converts the mud pulse pressure signal into an electrical signal through a signal sensing module. Based on the continuous acquisition of the electrical signal by the ground pressure wave acquisition module, the signal is converted into a computer-recognizable digital signal and transmitted to the ground computer, which serves as the signal processing mechanism. The mud pulse digital signal is decoded based on optimized variational mode decomposition and cross-correlation algorithms, which adaptively removes the influence of interference noise, improves the synchronization accuracy of the mud pulse signal during the decoding process, and controls the bit error rate. It is also applicable to situations with low signal-to-noise ratio and has high practicality.

[0050] In the drilling transmission pulse signal decoding device provided in this embodiment of the invention, each module or unit structure can operate independently or in combination according to actual data processing and computing requirements to achieve the corresponding technical effects.

[0051] Example 2 The device structure has been described in detail in the embodiments disclosed above. Based on the application of the device described in any one or more of the above embodiments, the present invention also provides a method for decoding transmission-while-drilling pulse signals. Specific embodiments are given below to illustrate the implementation process in detail.

[0052] Specifically, Figure 6 The diagram below illustrates a flowchart of the drilling transmission pulse signal decoding method provided in an embodiment of the present invention, as shown below. Figure 6 As shown, the method includes: Using a signal sensing module installed on the ground, mud pulse pressure signals after downhole encoding are continuously acquired and converted into mud pulse electrical signals; the mud pulse pressure signals are encoded using pulse position modulation. The pressure wave acquisition module continuously acquires mud pulse electrical signals from the signal sensing module, converts them into mud pulse digital signals, and then transmits them to the signal processing mechanism.

[0053] The downhole measurement data represented by the mud pulse signal is obtained by performing noise reduction and decoding operations based on optimized variational mode decomposition and cross-correlation algorithms by the signal processing mechanism.

[0054] The optimal variational mode decomposition of mud pulse signals is achieved by combining particle swarm optimization algorithm and variational mode decomposition algorithm in the optimization decomposition module of the signal processing mechanism.

[0055] Furthermore, in one embodiment, the process of optimizing variational mode decomposition of the mud pulse signal includes: Construct a suitable function and set the optimization range for the penalty factor α and the number of decompositions K; Evaluate the appropriate function value of each particle to determine whether each particle meets the population evolution stopping condition. If not, continue to seek optimization until the maximum population evolution preset value is met. The original mud pulse signal was decomposed using the obtained optimal parameters to obtain the intrinsic mode components of the signal. Based on the spectral characteristics of each intrinsic mode component, they are sequentially divided into random noise signal, pump noise signal, baseline signal, undecomposed signal and useful signal. The useful signal mode components are superimposed to obtain the denoised waveform.

[0056] Specifically, in one embodiment, the adequacy function is set as the ratio of the root mean square error of the original signal and the denoised signal (reconstructed signal) to the cross-correlation coefficient of the original signal and the denoised signal (reconstructed signal), where K∈[2,10] and α∈[100,5000]. Furthermore, in one embodiment, the process of classifying based on the spectral characteristics of each intrinsic mode component includes: Signals with a peak width greater than the first reference value are classified as random noise signals; signals with a peak position less than an integer multiple of the pump fundamental frequency are classified as pump noise signals; signals with a peak position less than the zero frequency are classified as baseline signals; signals with a peak position greater than the zero frequency are classified as undecomposed noise signals; and signals with a peak position greater than 0.5 / PW are classified as undecomposed noise signals. Signals that do not meet any of the above conditions are considered useful signals. The above reference values ​​are determined empirically and do not need to be adjusted according to well conditions. Typically, the first reference value is set to 1 / PW, the second reference value is set to 1 / PW, the third reference value is set to 0.1Hz, and the fourth reference value is set to 0.5 / PW.

[0057] A synchronization head correlator and a data block correlator are constructed respectively. The denoised waveform of the signal from the optimization decomposition module is cross-correlated with the synchronization head correlator and the data block correlator respectively to determine the starting position of the target decoded mud pulse signal and the information within the data block.

[0058] In a preferred embodiment, the process of optimizing variational mode decomposition of the mud pulse signal further includes: The waveform after denoising is cross-correlated with a preset synchronization head correlator, and the position corresponding to the maximum value of the correlated waveform is taken as the starting position of the mud pulse signal. Construct a correlator for each data block representing hexadecimal numbers 0x0 to 0xF. Perform cross-correlation processing between the denoised waveform and each data block correlator, and obtain the hexadecimal number corresponding to the maximum correlation value, which is the hexadecimal number represented by the waveform in that data block.

[0059] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0060] It should be noted that, in other embodiments of the present invention, the method can also combine one or more of the above embodiments to obtain a new decoding method for drilling transmission pulse signals, so as to provide refined protection for drilling measurement data in oil and gas exploration and development.

[0061] It should be noted that, based on the methods in any one or more embodiments of the present invention described above, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more embodiments, and when the code is executed by the operating system, it can implement the decoding method of the transmission pulse signal while drilling as described above.

[0062] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0063] The phrase "an embodiment" in the specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0064] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A decoding device for transmitting pulse signals while drilling, characterized in that, The device is installed in the ground area and includes: The pulse signal acquisition mechanism consists of a signal sensing module and a pressure wave acquisition module. The signal sensing module uses a pressure sensor and is configured to continuously acquire mud pulse pressure signals from downhole encoded processing and convert them into mud pulse electrical signals. The mud pulse pressure signals are encoded using pulse position modulation. The pressure wave acquisition module is configured to continuously acquire mud pulse electrical signals from the signal sensing module and convert them into mud pulse digital signals. The signal processing mechanism is connected to the pressure wave acquisition module of the pulse signal acquisition mechanism, receives the mud pulse digital signal from the pressure wave acquisition module, and performs denoising and decoding operations based on the optimized variational mode decomposition and cross-correlation algorithm to obtain the downhole measurement data represented by the mud pulse signal. The signal processing mechanism includes an optimization decomposition module, which uses a combination of particle swarm optimization algorithm and variational mode decomposition algorithm to achieve optimized variational mode decomposition of mud pulse signal; The optimization decomposition module includes: The decomposition parameter initialization unit is configured to construct a fitness function and set the optimization range of the penalty factor α and the number of decompositions K; the decomposition parameter initialization unit sets the fitness function to be the ratio of the root mean square error of the original signal and the denoised signal to the cross-correlation coefficient of the original signal and the denoised signal. The optimization evolution unit evaluates the appropriate function value of each particle and determines whether each particle meets the population evolution stopping condition. If it does not meet the condition, it continues to optimize until the maximum population evolution preset value is met. The signal decomposition unit performs VMD decomposition on the original mud pulse signal using the obtained optimal parameters to obtain the intrinsic mode components of the signal. The classification and denoising unit divides each intrinsic mode component into random noise signal, pump noise signal, baseline signal, unresolved signal and useful signal according to the spectral characteristics of each intrinsic mode component. The useful signal mode components are superimposed to obtain the denoised waveform. The classification and denoising unit performs classification as follows: signals with a peak width range greater than the first reference value are classified as random noise signals; signals with a peak position less than an integer multiple of the pump fundamental frequency are classified as pump noise signals; signals with a peak position less than the zero frequency are classified as baseline signals; signals with a peak position greater than the zero frequency are classified as undecomposed noise signals; and signals whose frequency range satisfies the condition that the peak position is greater than 0.5 / PW are classified as undecomposed noise signals. Signals that do not meet any of the above conditions are useful signals. The signal processing mechanism also includes a cross-correlation operation module, which is configured to construct a synchronization head correlator and a data block correlator respectively, and perform cross-correlation operations between the denoised waveform of the signal from the optimization decomposition module and the synchronization head correlator and the data block correlator respectively to determine the starting position of the target decoded mud pulse signal and the information within the data block.

2. The apparatus according to claim 1, characterized in that, The pressure wave acquisition module includes: An isolated safety barrier module, which is connected to a signal sensing module, is configured to process the mud pulse electrical signal from the signal sensing module into a stable mud pulse voltage signal. The data acquisition card module is connected to the isolated safety barrier module and is configured to acquire the mud pulse voltage signal of the isolated safety barrier module and then convert it into the corresponding mud pulse digital signal. The ground-based regulated power supply module, integrated with the isolated safety barrier module and the data acquisition card module, is installed on the ground at the site and configured to connect to the power grid to provide stable power to the signal sensing module and the isolated safety barrier module.

3. The apparatus according to claim 1, characterized in that, The cross-correlation operation module is configured to perform cross-correlation processing on the waveform after signal denoising and the synchronous head correlator, and obtain the position corresponding to the maximum value of the correlated waveform as the starting position of the mud pulse signal.

4. The apparatus according to claim 1, characterized in that, The cross-correlation operation module is configured to construct a data block correlator representing hexadecimal numbers 0x0 to 0xF, perform cross-correlation processing between the denoised waveform and each data block correlator, and obtain the hexadecimal number corresponding to the maximum correlation value, which is the hexadecimal number represented by the waveform in that data block.

5. A method for decoding pulse signals transmitted while drilling, characterized in that, The method is applied to the decoding device for transmission-while-drilling pulse signals as described in any one of claims 1 to 4, and the method includes: Using a signal sensing module installed on the ground, mud pulse pressure signals after downhole encoding are continuously acquired and converted into mud pulse electrical signals; the mud pulse pressure signals are encoded using pulse position modulation. The pressure wave acquisition module continuously acquires mud pulse electrical signals from the signal sensing module, converts them into mud pulse digital signals, and transmits them to the signal processing mechanism. The downhole measurement data represented by the mud pulse signal is obtained by performing denoising and decoding operations based on optimized variational mode decomposition and cross-correlation algorithms by the signal processing mechanism.

6. A storage medium, characterized in that, The storage medium stores program code that can implement the method as described in claim 5.

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