Wireless while-drilling pulse signal transmission system under high-temperature condition

Abstract

The invention relates to the technical field of signal transmission, in particular to a wireless while-drilling pulse signal transmission system under a high-temperature condition. The system comprises a signal generation part, a signal transmission part and a signal receiving part, the signal generation part is used for sensing changes of temperature, pressure or vibration of an underground environment through a piezoelectric crystal, generating an initial electric signal, forming a mechanical signal and converting the mechanical signal into an initial pulse signal in an electric signal form again; the signal transmission part is used for performing mud pressure modulation on the initial pulse signal to obtain a phase change function; performing nonlinear correction to obtain a correction result; performing signal coding modulation based on the correction result; the modulation signal is sent to a signal receiving part at a far end; and the signal receiving part is used for receiving the modulation signal and demodulating the modulation signal to obtain a demodulated output signal. A complete, efficient and reliable solution is provided for wireless while-drilling pulse signal transmission under the high-temperature condition.

Description

Technical Field

[0001] The invention belongs to the technical field of signal transmission, and in particular relates to a wireless drilling pulse signal transmission system under high temperature conditions. Background Art

[0002] Signal transmission while drilling is one of the key technologies in oil and gas drilling operations. Its core purpose is to transmit real-time data in the complex environment of the well, such as temperature, pressure, vibration, etc., to the ground for real-time monitoring and analysis. This technology has played an important role in improving drilling efficiency, optimizing geological data collection, and ensuring drilling safety. At present, signal transmission while drilling mainly relies on a variety of physical mechanisms such as mud pulse signals, radio waves, and sound waves. However, these technologies still have many problems under high temperature, high pressure and complex geological environments, which limits their application under extreme conditions.

[0003] Mud pulse signal technology is the most widely used method for signal transmission while drilling. Its basic principle is to generate pulse signals by changing the pressure in the mud flow, and then use pressure sensors to capture these signals to complete information transmission. This technology has certain anti-interference ability and stability, but it relies on mud flow as a signal medium, resulting in a low signal propagation speed (about 5~10 m / s), which cannot meet the needs of high-real-time data transmission. In addition, the noise interference in the mud flow is large, especially in high temperature and high pressure environments, the rheological changes of the mud will significantly affect the signal quality, and easily cause signal distortion or even loss. Although some improved technologies have been developed in recent years, such as high-frequency mud pulses and dual-frequency modulation, which have partially improved the anti-interference ability and transmission rate of the signal, there are still great limitations in its application under high temperature conditions. Radio wave transmission technology uses the propagation characteristics of electromagnetic waves in the downhole medium to transmit signals to the ground. Compared with mud pulse signals, radio wave transmission technology has a faster transmission speed (close to the speed of light) and a larger information bandwidth. However, the high-conductivity formations (such as salt rock layers) in the downhole environment absorb radio waves very significantly, resulting in serious signal attenuation. In addition, high temperature environment will have an unignorable impact on electronic components, especially the performance of core components such as antennas and amplifiers will degrade due to the increase in temperature, further reducing the stability of the signal. Although some high-temperature resistant electronic components and low-frequency radio wave transmission solutions have been developed, these improvements still cannot completely solve the problem of radio wave propagation in complex underground environments. Acoustic signal transmission technology realizes signal transmission through the propagation of mechanical waves in the well pipe wall or mud flow, and its propagation speed is between the mud pulse signal and the radio wave. Acoustic signals can effectively pass through highly conductive formations in some cases, solving the problem of excessive attenuation of radio waves. However, during the propagation process, acoustic signals are easily affected by underground mechanical vibrations, mud flow noise and formation reflections, resulting in distortion of the amplitude and phase of the signal, and increasing the difficulty of demodulation. In addition, the frequency of acoustic signals is low and the bandwidth is limited, which cannot support the transmission of high-capacity data, especially when a large amount of geological information needs to be transmitted in real time, showing obvious shortcomings. Summary of the invention

[0004] The main purpose of the present invention is to provide a wireless drilling pulse signal transmission system under high temperature conditions, which provides a complete, efficient and reliable solution for wireless drilling pulse signal transmission under high temperature conditions. Its significant advantages in stability, accuracy, anti-interference and adaptability make the invention show great potential in practical applications.

[0005] In order to solve the above problems, the technical solution of the present invention is achieved as follows: A wireless drilling-while-drilling pulse signal transmission system under high temperature conditions, the system comprising: a signal generating part, a signal transmitting part and a signal receiving part; the signal generating part is used to sense the change of temperature, pressure or vibration of the downhole environment through a piezoelectric crystal, generate an initial electrical signal, and convert the initial electrical signal into a pressure wave in the mud flow through an electromechanical device to form a mechanical signal, and the mechanical signal is captured by a sensor and reconverted into an initial pulse signal in the form of an electrical signal; the signal transmitting part is used to perform mud pressure modulation on the initial pulse signal by controlling the density of the mud flow, generate a wireless drilling-while-drilling pulse signal, and capture the phase change of the wireless drilling-while-drilling pulse signal during the propagation process to obtain a phase change function; based on the phase change function, perform nonlinear correction to obtain a correction result; based on the correction result, perform signal coding modulation to obtain a modulated signal; and send the modulated signal to a remote signal receiving part; the signal receiving part is used to receive the modulated signal and perform signal demodulation to obtain a demodulated output signal.

[0006] Furthermore, the signal generating part places a piezoelectric crystal inside the drilling tool. When the temperature, pressure or vibration in the downhole environment changes, an initial electrical signal is generated at both ends of the piezoelectric crystal through the piezoelectric effect; the material of the piezoelectric crystal is lanthanum-modified lead zirconate titanate; the drilling tool is filled with mud flow, and the electrical signal generated by the piezoelectric crystal drives the electromechanical device to change the flow state of the mud flow through coupling with the electromechanical device, and converts the initial electrical signal into a pressure wave in the mud flow to form a mechanical signal; the electromechanical device is an electromechanical pulser; the sensor is also placed directly inside the drilling tool, and through direct contact with the mud flow, it senses the change in pressure waves and reconverts the mechanical signal into an initial pulse signal in the form of an electrical signal.

[0007] Furthermore, the initial electrical signal is expressed using the following formula: ; in, The piezoelectric crystal is at a temperature of When , the initial electrical signal generated; The piezoelectric crystal is at standard temperature The reference output voltage when is the thermal activation energy of the material of the piezoelectric crystal; is the Boltzmann constant; is temperature; : Temperature quadratic coefficient, which is the preset value; is the oscillation reference frequency of the piezoelectric crystal; For time.

[0008] Furthermore, the mechanical signal is expressed using the following formula: ; in, The radial distance from the inside of the drilling tool to the axis is , the distance along the axial direction is , the temperature is When the mechanical signal is formed; is the longitudinal piezoelectric coefficient of the piezoelectric crystal; is the characteristic influence radius of the piezoelectric crystal; is the effective length of the piezoelectric crystal; is the elastic modulus of the piezoelectric crystal at standard temperature; For temperature The elastic modulus at ; is Poisson's ratio; is the boundary effect coefficient, which is the preset value; It is the maximum distance from the outer surface of the drilling tool in the axial direction.

[0009] Furthermore, the initial pulse signal is expressed using the following formula: ; in, is the initial pulse signal; is the temperature attenuation coefficient, which is the preset value; is a preset first mechanical-electrical conversion efficiency coefficient; is the signal angular frequency, .

[0010] Furthermore, the wireless drilling pulse signal is expressed using the following formula: ; in, The propagation distance is Time Wireless drilling pulse signal at the same time; is a preset second mechanical-electrical conversion efficiency coefficient; is the mud flow density at standard temperature; For temperature The mud flow density at ; is the pressure wave propagation attenuation coefficient, which is the set value; is the modulation frequency; is the modulation phase; is the modulation amplitude factor, is the set value; is the thermal expansion coefficient of the mud flow.

[0011] Furthermore, the phase change function is expressed using the following formula: ; in, For temperature The wavelength of the wireless while drilling pulse signal; is the temperature phase coupling coefficient, is the set value; based on the phase change function, the nonlinear correction is performed through the following formula to obtain the correction result : ; in, is the nonlinear correction coefficient, is the set value; is the universal gas constant.

[0012] Furthermore, the modulation signal is expressed by the following formula: ; in, is the average density of the mud flow.

[0013] Furthermore, after receiving the modulated signal, the signal receiving part executes the inverse process of signal modulation, performs signal demodulation, and obtains a demodulated output signal.

[0014] The wireless pulse signal transmission system for drilling under high temperature conditions of the present invention has the following beneficial effects: First, the present invention uses lanthanum-modified lead zirconate titanate (PLZT) as the main material of the piezoelectric crystal, which significantly improves the performance stability of the signal generation part in a high temperature environment. PLZT has excellent high temperature resistance, and its piezoelectric coefficient and elastic modulus can remain stable under high temperature conditions above 200°C, thereby ensuring the sensitive response of the piezoelectric crystal to changes in downhole temperature, pressure and vibration. Compared with traditional piezoelectric materials that are prone to performance degradation in high temperature environments, the material selection of the present invention effectively improves the long-term reliability of the system in extreme environments, providing a high sensitivity and high precision basis for signal generation.

[0015] Secondly, the signal modulation mechanism of the present invention solves the problems of signal distortion and noise interference in complex underground environments by introducing a dynamic nonlinear correction algorithm. By constructing a correction model based on a phase change function, the present invention can capture the phase drift and amplitude attenuation of the signal during propagation, and correct the signal distortion in real time through a nonlinear algorithm. The correction formula introduces multi-dimensional parameters such as temperature, propagation distance, and medium characteristics, so that the system can dynamically adjust the correction results, thereby ensuring the integrity and stability of the modulated signal. This intelligent correction method can significantly improve the anti-interference ability and demodulation accuracy of the signal in long-distance propagation.

[0016] The present invention also fully considers the physical properties of mud flow as a medium during signal transmission. By dynamically adjusting the density and flow rate of the mud flow and introducing a pressure wave propagation attenuation model, the present invention can optimize the energy distribution and propagation efficiency of the signal. In particular, by designing real-time correction items based on temperature and density changes, the system can compensate for changes in the physical properties of the mud flow caused by high temperature, thereby improving the reliability of the signal during propagation. Compared with the signal attenuation and loss caused by fluctuations in the physical properties of the mud flow in the prior art, the present invention shows significant advantages in medium adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the system structure of a wireless while-drilling pulse signal transmission system under high temperature conditions provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments described herein can be implemented in an order other than that shown or described herein.

[0019] Example 1, reference Figure 1 : A wireless downhole pulse signal transmission system under high temperature conditions, the system comprising: a signal generating part, a signal transmitting part and a signal receiving part; the signal generating part is used to sense the changes in temperature, pressure or vibration of the downhole environment through a piezoelectric crystal to generate an initial electrical signal, and to convert the initial electrical signal into a pressure wave in the mud flow through an electromechanical device to form a mechanical signal, which is captured by a sensor and reconverted into an initial pulse signal in the form of an electrical signal; the signal transmitting part is used to perform mud pressure modulation on the initial pulse signal by controlling the density of the mud flow to generate a wireless downhole pulse signal, and to capture the phase change of the wireless downhole pulse signal during the propagation process to obtain a phase change function; based on the phase change function, nonlinear correction is performed to obtain a correction result; based on the correction result, signal coding modulation is performed to obtain a modulated signal; the modulated signal is sent to a remote signal receiving part; the signal receiving part is used to receive the modulated signal and perform signal demodulation to obtain a demodulated output signal.

[0020] Specifically, first of all, the signal generation part is the core of the whole system. It senses the physical changes of the downhole environment through piezoelectric crystals and generates the corresponding initial electrical signals. The working principle of piezoelectric crystals is based on the piezoelectric effect, that is, when the material is subjected to mechanical stress, the electric dipole moment inside it will be rearranged, resulting in a potential difference proportional to the stress at both ends. This phenomenon is of great significance in the drilling environment, because the temperature, pressure and vibration changes of the downhole environment can act on the piezoelectric crystal in the form of mechanical stress or thermal stress, thereby generating corresponding electrical signals. For example, when the pressure at the drill bit changes, the piezoelectric crystal will sense the dynamic change of this pressure and generate an electrical signal whose amplitude and frequency are proportional to the amplitude and frequency of the pressure change. Similarly, changes in temperature and vibration can also act on the piezoelectric crystal through thermal expansion effect and mechanical vibration to generate specific electrical signals. In this way, a variety of physical parameters in the complex downhole environment are successfully converted into measurable electrical signals.

[0021] However, the electrical signal directly generated by the piezoelectric crystal is not suitable for direct long-distance transmission because the downhole signal will be strongly attenuated and interfered by noise. Therefore, the signal generation part further converts the initial electrical signal into a pressure wave in the mud flow, and this process is realized by an electromechanical device. The electromechanical device applies the mechanical vibration driven by the electrical signal to the mud flow, causing the mud to produce corresponding pressure changes. As a medium for signal propagation, the mud has continuity and fluidity, and the pressure wave can propagate to the far end along the mud flow direction. In this process, the characteristics of the mud flow directly determine the efficiency and quality of signal propagation, and the mud pressure wave provides the basis for subsequent signal modulation. The signal transmission part uses the mud flow as a carrier and optimizes the initial signal by means of mud pressure modulation. The principle of mud pressure modulation can be understood as dynamically adjusting the density or flow rate of the mud to change the propagation characteristics of the pressure wave, thereby superimposing the changing characteristics of the electrical signal on the pressure wave. Specifically, after the initial electrical signal is converted, it becomes a pressure wave signal with a specific frequency and amplitude. The mud pressure modulation part performs amplitude modulation or phase modulation on the pressure wave according to the transmission requirements to ensure that the signal has high anti-interference ability and identifiability during the propagation process. For example, in amplitude modulation, the density of the mud flow is dynamically adjusted to change the amplitude of the pressure wave to encode the signal information. In phase modulation, the phase offset of the pressure wave is adjusted by controlling the mud flow rate or resistance, so that the signal can represent different information in different phase states.

[0022] The wireless downhole pulse signal propagating in the mud flow will inevitably be affected by high temperature, high pressure and complex geological conditions, resulting in phase drift and other nonlinear effects. These effects will cause signal distortion, which in turn affects the integrity of the information. To solve this problem, the signal transmission part is specially designed with a phase change capture and nonlinear correction mechanism. Phase change refers to the waveform phase offset caused by environmental factors during signal propagation, and its mathematical expression can be described by a dynamic function. The system can extract the specific change characteristics of the phase, and then use the nonlinear correction algorithm to compensate and correct it. The principle of nonlinear correction is to establish a nonlinear relationship model between the pressure wave phase and environmental changes, calculate the correction amount to be compensated, and superimpose it on the initial signal to restore the original signal characteristics. After completing the signal correction, the signal transmission part also encodes and modulates the signal to enhance the transmission efficiency and anti-interference ability. The process of encoding and modulation remaps the corrected signal into a higher-dimensional coding space, such as by using a combination of multiple pulse widths, amplitudes and frequencies to represent different information units. This encoding method not only improves the redundancy of the signal, but also enhances its identifiability in a noisy environment. The modulated signal is sent to the signal receiving part on the ground to complete the entire process of signal transmission. The task of the signal receiving part is to receive and demodulate the modulated signal from the mud flow, and finally restore the original information of the downhole environment. During the receiving process, the mud pressure wave is first captured by the sensor and converted into an electrical signal. This electrical signal contains all the modulation characteristics previously experienced in the transmission link, so it is necessary to go through the demodulation process to restore the original information. The first step of demodulation is to filter and denoise the signal to remove the noise components introduced by environmental interference. Subsequently, the modulated signal is converted into a corrected initial signal through a decoding rule consistent with the sending end, and finally the downhole environmental information is demodulated. This process ensures that the signal can maintain the integrity and accuracy of the information during the long-distance transmission from the downhole to the ground.

[0023] Embodiment 2: The signal generating part places a piezoelectric crystal inside the drilling tool. When the temperature, pressure or vibration in the downhole environment changes, an initial electrical signal is generated at both ends of the piezoelectric crystal through the piezoelectric effect. The material of the piezoelectric crystal is lanthanum-modified lead zirconate titanate. The drilling tool is filled with mud flow. The electrical signal generated by the piezoelectric crystal drives the electromechanical device to change the flow state of the mud flow through coupling with the electromechanical device, and converts the initial electrical signal into a pressure wave in the mud flow to form a mechanical signal. The electromechanical device is an electromechanical pulser. The sensor is also placed directly inside the drilling tool, and senses the change in pressure waves by directly contacting the mud flow, and converts the mechanical signal back into an initial pulse signal in the form of an electrical signal.

[0024] Specifically, in this embodiment, the piezoelectric crystal uses lanthanum-modified lead zirconate titanate (PLZT) material, which is a piezoelectric ceramic material with excellent performance. PLZT material has a high piezoelectric coefficient and good high temperature resistance, and can withstand high temperatures of more than 200°C in a drilling environment while maintaining a stable electrical signal output capability. The piezoelectric effect of this material comes from the polarization effect of its internal lattice structure under mechanical stress. When the pressure changes, the vibration increases, or the temperature rises in the downhole environment, these external physical changes will directly act on the piezoelectric crystal in the form of mechanical stress or thermal stress, causing the internal electric dipole moment to rearrange, thereby generating a potential difference proportional to the external stimulus at both ends of the piezoelectric crystal. Through this process, the environmental information inside the drilling tool is successfully converted into the corresponding initial electrical signal. Due to the high sensitivity and low loss characteristics of PLZT materials, the amplitude and frequency of these signals can accurately reflect the dynamic changes of the downhole environment. After the piezoelectric crystal generates an electrical signal, it is further converted into a mechanical signal through its coupling with the electromechanical device. The electromechanical device in this embodiment uses an electromechanical pulser, and its core working principle is to use electrical signals to drive the movement of mechanical parts to change the flow state of the mud flow inside the drilling tool. Specifically, the initial electrical signal generated by the piezoelectric crystal will be directly transmitted to the electromechanical pulser, driving its internal mechanical structure to periodically open or close the mud flow channel. This process will produce periodic pressure fluctuations in the mud flow, forming corresponding mechanical signals. As a medium for signal transmission, the physical properties of the mud flow play a decisive role in the propagation effect of the pressure wave. Since the mud flow has a certain fluidity and viscosity, the pressure wave formed inside the drilling tool can propagate to the far end along the direction of the mud flow. In this way, the dynamic change information of the downhole environment is encoded into the pressure wave signal in the mud flow, laying the foundation for the subsequent signal detection and transmission.

[0025] At the same time, in order to achieve signal reproduction and transmission, the system also sets a sensor inside the drilling tool to directly detect the pressure wave changes in the mud flow. This sensor maintains direct contact with the mud flow and can sense the key characteristic parameters such as the amplitude, frequency and phase of the pressure wave in real time. The pressure wave in the mud flow is a typical mechanical signal that contains information about changes in the downhole environment. However, this mechanical signal cannot be directly used for long-distance information transmission, so it needs to be converted back into an electrical signal. The sensor restores the initial pulse signal originally generated by the piezoelectric crystal by converting the mechanical energy of the pressure wave into an electrical signal. It should be noted that during the propagation of the mud flow, due to the influence of high temperature, high pressure and complex geological conditions, the pressure wave signal may be attenuated and distorted to a certain extent. In order to ensure the integrity of the signal, the sensor is designed with a highly sensitive detection mechanism, which retains the characteristics of the original signal to the maximum extent by accurately capturing the slight changes in the pressure wave. The signal generation and transmission process in this embodiment is a cycle of multiple energy conversions. In the downhole environment, the changes in temperature, pressure and vibration first act on the piezoelectric crystal in the form of mechanical stress to generate the corresponding electrical signal; then, the electrical signal drives the pressure wave change of the mud flow through the electromechanical device to complete the conversion into a mechanical signal; then, the mechanical signal in the mud flow is converted into an electrical signal through the sensor and restored to the initial pulse signal. This cycle makes full use of the efficient conversion characteristics of energy between different forms, so that the downhole environmental information can be successfully transmitted to the remote end through the special medium of mud flow. It is worth mentioning that the design in Example 2 fully considers the complexity of the downhole environment and the influence of high temperature conditions on material properties and signal transmission. As the main component of the piezoelectric crystal, PLZT material has excellent thermal stability and fatigue resistance, and can still maintain stable electrical signal output in a high temperature environment; the electromechanical device ensures the stability and controllability of pressure wave generation by optimizing the mechanical structure and driving mode; the direct contact design of the sensor improves the capture accuracy of the pressure wave signal and reduces the attenuation of the signal by the intermediate medium. The combination of these technical means makes the signal generation, transmission and reconstruction process of the system in the extreme downhole environment more reliable and efficient.

[0026] Embodiment 3: The initial electrical signal is expressed using the following formula: ; in, The piezoelectric crystal is at a temperature of When , the initial electrical signal generated; The piezoelectric crystal is at standard temperature The reference output voltage when is the thermal activation energy of the material of the piezoelectric crystal; is the Boltzmann constant; is temperature; : Temperature quadratic coefficient, which is the preset value; is the oscillation reference frequency of the piezoelectric crystal; For time.

[0027] Specifically, the formula describes the combined effect of temperature on electrical signals through an exponential function and a square correction term of temperature, in which the thermal activation effect is a key factor. When a piezoelectric crystal is placed in a high-temperature underground environment, the arrangement state of its internal electric dipole moment changes with the increase in temperature. This phenomenon is explained by the thermal activation energy of the material. , the formula quantitatively expresses the influence of thermal activation energy, where represents the thermal activation energy of the piezoelectric material, is the Boltzmann constant, is the current absolute temperature. When the temperature rises, the internal structure of the piezoelectric crystal obtains more thermal energy, and the electric dipole moment is easier to align, resulting in an increase in the amplitude of the output signal. Conversely, in a low temperature environment, the thermal activation effect is weaker and the amplitude of the output signal decreases. This description can accurately reflect the electrical output behavior of piezoelectric crystal materials under different temperature conditions, and provides a reliable physical basis for signal generation in high-temperature environments underground. At the same time, in order to more carefully characterize the nonlinear effect of high-temperature environments on piezoelectric crystals, the formula introduces a correction term proportional to the square of the temperature change This correction term reflects the piezoelectric material at standard temperature. The characteristics near the deviate from the law, especially at temperatures significantly above or below When the nonlinear change of material properties is more obvious. Correction coefficient It is a key parameter calibrated experimentally to quantify the strength of nonlinear temperature effects. When the temperature change is small, the output of the signal is dominated by the thermal activation effect; when the temperature deviates significantly from the standard value, the nonlinear correction term will play a more significant role, ensuring that the signal output can accurately reflect the temperature changes in extreme environments. This correction method is particularly important in actual drilling applications, because the downhole environment usually has significant temperature gradients or instantaneous changes, and this model can capture these dynamic characteristics. The time factor of the formula It reflects the natural oscillation characteristics of the piezoelectric crystal under mechanical vibration or alternating stress. This part makes the signal dynamic and gives the initial electrical signal a periodic fluctuation characteristic. It is the reference oscillation frequency of the piezoelectric crystal, which is closely related to the physical size, material properties and vibration mode of the crystal. This oscillation behavior is not only an inherent property of the piezoelectric crystal signal generation, but also the basis for signal modulation and subsequent transmission. In the process of downhole signal transmission, the periodic oscillation signal can enhance the anti-interference ability of the transmission through frequency domain modulation, and provide a clear frequency reference for subsequent signal detection and demodulation.

[0028] Embodiment 4: The mechanical signal is expressed using the following formula: ; in, The radial distance from the inside of the drilling tool to the axis is , the distance along the axial direction is , the temperature is When the mechanical signal is formed; is the longitudinal piezoelectric coefficient of the piezoelectric crystal; is the characteristic influence radius of the piezoelectric crystal; is the effective length of the piezoelectric crystal; is the elastic modulus of the piezoelectric crystal at standard temperature; For temperature The elastic modulus at ; is Poisson's ratio; is the boundary effect coefficient, which is the preset value; It is the maximum distance from the outer surface of the drilling tool in the axial direction.

[0029] Specifically, the strength of the mechanical signal The initial electrical signal generated by the piezoelectric crystal The mechanical signal intensity is related to the The change in the initial electrical signal directly determines the overall amplitude of the mechanical signal. The effect of temperature has been taken into account, and the mechanical signal formula is further improved by The longitudinal piezoelectric coefficient of the crystal Combined with the above, the conversion of electrical signals into mechanical signals is completed. It reflects the piezoelectric properties of the material and is a key parameter in the signal generation process. This means that the material produces a stronger mechanical response under the drive of the electrical signal, thereby enhancing the intensity of the mud pressure wave. The radial distribution characteristics of the mechanical signal are expressed by a Gaussian attenuation function. It shows that the signal strength varies with the radial distance from the axis. This Gaussian distribution model accurately describes the local influence range of the piezoelectric crystal, the characteristic influence radius It is the core parameter that determines the coverage of the mechanical signal in the radial direction. In the design of drilling tools, Affected by crystal size, material properties and signal frequency, its optimized design directly affects the transmission efficiency of mechanical signals. Since the pressure wave in the mud flow propagates radially and axially, the Gaussian attenuation characteristics of the signal ensure that the pressure wave gradually weakens when it moves away from the axis, thereby limiting the ineffective diffusion of the signal and enhancing the stability of signal modulation. The axial distribution characteristics are corrected by a cosine function. Description, this item reflects the mechanical signal in the effective length of the crystal The distribution law within the range. Since the driving force on the piezoelectric crystal is not uniformly distributed in the axial direction, the mechanical response of the two end areas is weak, while the middle area shows a stronger mechanical signal intensity. The periodic characteristics of the cosine function appropriately capture this distribution feature, so that the formula can accurately reflect the fluctuation law of the mechanical signal in the axial direction. This law not only conforms to the physical stress distribution pattern, but also has important significance for the modulation process of the mud flow pressure wave.

[0030] The formula further combines the temperature dependence and dynamic response behavior of the material to show the complex nonlinear characteristics of the mechanical signal. and elastic modulus at standard temperature The formula introduces the influence of material rigidity changing with temperature. Determines the degree of deformation of the material under the action of external force. Its value may be significantly reduced at high temperatures, thereby weakening the strength of the mechanical signal. and , the formula can dynamically adjust the amplitude of the mechanical signal to reflect the trend of material stiffness changing with temperature. In addition, Poisson's ratio The introduction of further supplements the lateral and longitudinal coupling effects of the material under stress, which is manifested as the periodic fluctuation characteristics of the mechanical signal in the radial distribution. This dynamic adjustment mechanism ensures that the generation of mechanical signals can accurately adapt to the changes in material properties in the high-temperature environment downhole. The temperature derivative correction term It is used to capture the nonlinear response of temperature changes to mechanical signals. It has shown sensitivity to temperature changes, and its derivative with respect to temperature It can directly reflect the dynamic influence of the temperature change rate on the signal. Through this correction term, the formula effectively compensates for the discontinuity of the mechanical signal that may be caused by too fast temperature change, thereby ensuring the stability of the system in a dynamic temperature environment. The boundary effect is reduced by an exponential decay term. Performance, including is the maximum distance from the outer surface of the drilling tool along the axial direction. This term describes the phenomenon that the mechanical signal gradually weakens due to energy dissipation when it approaches the boundary. This boundary effect is an important characteristic in the propagation of mechanical signals and directly affects the spatial distribution and effective range of the signal. The formula can flexibly adapt to the requirements of different drilling tool structures for boundary effects and ensure that the signal strength has a reasonable distribution inside the tool.

[0031] Embodiment 5: The initial pulse signal is expressed using the following formula: ; in, is the initial pulse signal; is the temperature attenuation coefficient, which is the preset value; is a preset first mechanical-electrical conversion efficiency coefficient; is the signal angular frequency, .

[0032] Specifically, the formula shows that the generation process of the initial pulse signal is determined by the strength and conversion efficiency of the mechanical signal. It expresses the intensity distribution of pressure waves in mud flow, which is affected by radial distance. , axial distance and ambient temperature The mechanical signal comes from the initial electrical signal of the piezoelectric crystal in the high-temperature downhole environment. The pressure wave generated by electromechanical conversion propagates in the mud and is affected by the internal environment of the drilling tool. The formula for generating the initial pulse signal is based on the mechanical signal strength and a preset mechanical-electrical conversion efficiency coefficient. Combined with other technologies, the quantitative description of mechanical signals to electrical signals is completed. It is a key parameter that reflects the performance of the electromechanical conversion device in the system, including the comprehensive effects of material properties, mechanical design and signal coupling. The conversion efficiency directly determines the amplitude of the initial pulse signal, thus affecting the quality of subsequent signal modulation and transmission. The effect of temperature on the initial pulse signal is reflected in the formula through two core parts: one is the relative temperature correction term , and the second is the temperature attenuation factor The relative temperature correction term describes the electrical signal generated by the piezoelectric crystal relative to the reference temperature. With the change of temperature As the temperature rises, the thermal activation effect inside the crystal increases, making As the temperature increases, the amplitude of the initial pulse signal also increases accordingly. However, the material properties in a high temperature environment do not increase linearly. In fact, the amplitude will decay due to the decrease in elastic modulus and the decay of electrical properties. This inhibitory effect is introduced. is the temperature attenuation coefficient, which, as the preset value of experimental calibration, reflects the performance stability of piezoelectric materials at high temperatures. Through the balance of these two parts, the formula can capture the signal enhancement caused by the thermal activation effect and correct the attenuation caused by the degradation of material performance in a high temperature environment, so that the initial pulse signal can maintain a stable output under high temperature conditions.

[0033] The dynamic characteristics of the signal are determined by the time oscillation term Expression, where is the angular frequency of the signal, which depends on the oscillation reference frequency of the piezoelectric crystal . The oscillation characteristics of the signal are the basis of frequency domain modulation in the entire system, and are also the key to the anti-interference ability during the propagation of the while-drilling pulse signal. Through the periodic sinusoidal form, the initial pulse signal not only carries the amplitude information from the mechanical signal, but also has a clear frequency characteristic, which provides a benchmark for the subsequent signal demodulation. The stability of the oscillation frequency directly affects the reliability of the signal in the mud flow propagation, and this frequency is usually determined by the material properties and design parameters of the piezoelectric crystal. In the complex downhole environment, frequency stability is crucial because the signal propagation process needs to resist high noise interference and the weakening effect of the formation on the signal. In addition, the comprehensive term in the formula integrates the intensity distribution, temperature response and time characteristics of the mechanical signal to form a complete signal generation model. The intensity distribution of the mechanical signal originates from the spatial distribution characteristics of the piezoelectric crystal and is limited by the radial and axial distances. The temperature response reflects the regulatory effect of the ambient temperature on the signal generation process, including the dual effects of thermal activation effect and high-temperature material performance attenuation. The time characteristic gives the signal dynamic characteristics through the sinusoidal oscillation form, so that it has frequency characteristics and time domain change rules. The organic combination of the three enables the initial pulse signal to not only reflect the downhole environmental parameters, but also be output in a dynamic and modulatable form, providing a basis for the subsequent processing of wireless while-drilling signals.

[0034] Embodiment 6: The wireless drilling pulse signal is expressed using the following formula: ; in, The propagation distance is Time Wireless drilling pulse signal at the same time; is a preset second mechanical-electrical conversion efficiency coefficient; is the mud flow density at standard temperature; For temperature The mud flow density at ; is the pressure wave propagation attenuation coefficient, which is the set value; is the modulation frequency; is the modulation phase; is the modulation amplitude factor, is the set value; is the thermal expansion coefficient of the mud flow.

[0035] Specifically, the wireless drilling pulse signal in the formula Depends on the initial pulse signal Input characteristics, mechanical-electrical signal conversion efficiency coefficient It amplifies or adjusts the amplitude of the signal. Conversion efficiency coefficient It is determined by system design and material selection, and describes the efficiency of energy conversion and distribution of the initial pulse signal after entering the mud medium. The value can ensure that the wireless drilling pulse signal has a stronger amplitude, thereby improving the signal's ability to resist attenuation during long-distance transmission. The temperature dependence of mud flow density is expressed by the term reflect, and are the mud density at standard temperature and current temperature respectively. The change of density of mud flow The density of the mud flow is reduced due to the thermal expansion effect. This change directly affects the performance of the mud as a signal propagation medium. By introducing the density ratio, the formula can dynamically adjust the amplitude of the wireless signal to compensate for the change in medium performance caused by the temperature increase. The adjustment of the mud flow density is the key to the stability of signal propagation, because the change in density not only affects the propagation speed and attenuation of the pressure wave, but also affects the transmission efficiency and amplitude strength of the signal. The spatial attenuation of the pressure wave propagation is given by the term Indicates that is the set pressure wave propagation attenuation coefficient, is the propagation distance. The propagation of pressure waves in mud flow will inevitably gradually attenuate due to energy loss and medium absorption. Attenuation coefficient It is a constant preset based on the physical properties of the mud flow, mud density, viscosity and other factors, which determines the degree of signal loss in long-distance transmission. Through this term, the formula can accurately describe the amplitude drop caused by energy dissipation during the signal propagation process, thus providing a theoretical basis for designing more efficient signal transmission strategies. Signal modulation characteristics are determined by modulation frequency. , Phase and modulation amplitude factor The introduction of , forms the high-frequency oscillation and dynamic change characteristics of the signal. Modulation frequency and Phase Determines the frequency domain characteristics of the signal and directly affects the signal's recognition and anti-interference capabilities. The dynamic range of the signal is further enhanced, so that the wireless pulse signal while drilling can adapt to complex environmental changes within a certain range during the propagation process. These modulation characteristics provide a clear reference for the frequency domain modulation and demodulation of the signal, so that the downhole signal can be effectively decoded when it propagates to the ground through the mud flow. The last term of the formula The complex influence of the thermal expansion effect of mud flow and the thermal activation behavior of piezoelectric crystal on the signal is comprehensively described. It characterizes the volume change of the mud flow caused by temperature change. The increase in temperature will cause the mud flow to expand, affecting the signal propagation path and medium density. On the other hand, the thermal activation effect of the piezoelectric crystal is The contribution of the temperature to the signal amplitude increases with the increase of temperature, but is negatively affected by the expansion of mud. The formula successfully balances the temperature effect in the signal generation and propagation process through the joint modeling of these two items, ensuring the stability of the wireless downhole pulse signal in a complex thermodynamic environment.

[0036] Embodiment 7: The phase change function is expressed using the following formula: ; in, For temperature The wavelength of the wireless while drilling pulse signal; is the temperature phase coupling coefficient, is the set value; based on the phase change function, the nonlinear correction is performed through the following formula to obtain the correction result : ; in, is the nonlinear correction coefficient, is the set value; is the universal gas constant.

[0037] Specifically, the phase change function Describes the signal propagation distance mathematically and temperature The combined effect on the phase. The phase change of the signal is directly related to the wavelength on the propagation path. The wireless drilling pulse signal is at temperature The propagation characteristic parameters under the conditions are significantly affected by the density and temperature of the medium. Describes the propagation distance Linear contribution to phase. As the propagation distance increases, the cumulative change of phase increases linearly, but the complexity of the underground high temperature environment makes this change not a simple linear behavior. The phase temperature correction term in the formula The amplitude characteristics of the wireless drilling pulse signal and the temperature coupling effect are combined. It reflects the relative change of signal amplitude. The propagation distance is The wireless drilling pulse signal strength at is the reference signal amplitude. The change in amplitude reflects the energy distribution law of the signal during propagation, and is also closely related to the phase of the signal. Temperature phase coupling coefficient Describes the correction effect of temperature change on the phase, It indicates the value of the ambient temperature deviation from the reference temperature. When the temperature rises, the physical properties of the medium change, resulting in changes in the signal propagation speed and wavelength, which in turn produces a temperature-dependent shift in the phase. Through this correction, the formula can dynamically capture the phase drift of the signal at different temperatures. Based on the phase change function, the nonlinear correction formula further processes the signal distortion and generates a correction result. The nonlinear correction process aims to compensate for the distortion caused by nonlinear effects and environmental factors during signal propagation, ensuring that the final signal can be accurately restored. The correction formula is based on the nonlinear correction coefficient As a benchmark, combined with the phase change function and mechanical signal strength Dynamically adjust the signal. The core part of the formula represents the contribution of phase change to the correction result, where It is the phase nonlinear adjustment factor. The nonlinear correction of the phase directly affects the amplitude and dynamic range of the correction result through this term, ensuring that the signal can be effectively compensated in a complex environment. The exponential attenuation term in the nonlinear correction formula The combined effect of mechanical signal strength and temperature on signal correction is further considered. The initial electrical signal generated by the piezoelectric crystal is affected by the temperature, pressure and spatial distribution of the downhole environment. is the universal gas constant, which is used to quantify the weakening effect of temperature on mechanical signals. As the ambient temperature increases, the mechanical signal attenuates due to the change of the medium during the propagation process, and this effect is reflected in the correction result through the exponential term. The exponential decay form ensures that under extreme high temperature conditions, the correction formula can dynamically adjust the compensation amplitude of the signal, thereby maximizing the restoration of the original characteristics of the signal. Through the combined use of the phase change function and the nonlinear correction formula, the system realizes the dynamic correction and accurate restoration of the wireless downhole pulse signal. In the high-temperature downhole environment, the propagation of the signal is inevitably disturbed by complex factors, including temperature gradient, mud flow density changes, and the inhomogeneity of medium characteristics. The phase change function provides a theoretical basis for the correction process by accurately describing the combined influence of the propagation path and temperature effect on the signal phase. On this basis, the nonlinear correction formula further dynamically adjusts the amplitude and phase of the signal to ensure that the final signal can maintain high fidelity in a complex environment. This process effectively improves the signal transmission efficiency and demodulation accuracy of the system, and provides strong support for the stable transmission of wireless downhole pulse signals under high temperature conditions.

[0038] Embodiment 8: The modulation signal is expressed by the following formula: ; in, is the average density of the mud flow.

[0039] Specifically, the first part of the formula The wireless drilling pulse signal is combined with the nonlinear correction result to form the amplitude basis of the modulation signal. Describes the energy distribution of the signal on the propagation path, which is affected by many factors such as mud flow density, temperature, propagation distance, etc. Nonlinear correction results This further compensates for the signal distortion caused by changes in medium properties during the propagation process. Through the combination of the two, the modulated signal has dynamic adaptability in amplitude and can maintain accurate expression of the initial information in a complex underground environment. The attenuation effect on the propagation path is calculated by the item Reflection, among which is the propagation distance, It is the characteristic distance of signal propagation. Mud flow is the propagation medium of the signal. Its internal energy absorption and scattering effects cause the signal to gradually attenuate during the propagation process. Characteristic distance It is a parameter set according to the physical properties of the mud flow, such as density, viscosity and flow rate, and is used to quantify the energy loss of the signal on the propagation path. This exponential term describes the attenuation law of the signal amplitude with the propagation distance, ensuring that the modulated signal can reflect the actual propagation conditions and providing a theoretical basis for long-distance signal transmission. The time dependence and phase characteristics of the signal are determined by the sinusoidal term Description. This term integrates the base frequency of the signal , phase change function , and the modulation frequency The dynamic modulation characteristics introduced. Reference frequency It is the core oscillation characteristic of the signal, determined by the natural frequency of the piezoelectric crystal, and provides a frequency reference for signal modulation. Phase change function The dynamic modulation characteristic reflects the comprehensive influence of propagation distance and temperature on the signal phase. According to the previous analysis, it combines the propagation path, mud medium characteristics and temperature effect, and can accurately describe the change law of signal phase. Introduce, where is the mechanical-electrical conversion efficiency coefficient, is the second mechanical-electrical conversion efficiency coefficient. Modulation frequency It characterizes the high-frequency modulation characteristics of the signal, making the modulated signal resolvable and anti-interference in the frequency domain. The dynamic modulation term is superimposed on the reference phase of the signal in a sinusoidal form, so that the modulated signal not only exhibits periodic oscillations in the time domain, but also exhibits complex modulation characteristics in the frequency domain. This multi-level modulation method ensures that the signal can carry more environmental information while enhancing anti-interference capabilities. The amplitude correction term in the formula The nonlinear amplitude change of the signal is further adjusted. The average density of the mud flow It is a key parameter of the signal propagation medium, and its change directly affects the amplitude strength of the signal. By introducing the logarithmic correction term, the formula can effectively smooth the drastic changes in the signal amplitude, avoiding excessive amplitude fluctuations caused by changes in the propagation path and medium, thereby improving the stability of the signal and the demodulation accuracy. This correction mechanism is particularly suitable for the signal propagation requirements under the coupling of multiple physical fields in complex underground environments.

[0040] Embodiment 9: After receiving the modulated signal, the signal receiving part executes the inverse process of signal modulation, performs signal demodulation, and obtains a demodulated output signal.

[0041] Specifically, the modulated signal is captured by the signal receiving part after being propagated over a long distance in the underground environment. Due to the nonlinear characteristics of the mud flow, the complexity of the high-temperature environment, and the energy loss in the propagation path, the received signal is often subject to various interferences and distortions. Therefore, the signal receiving part needs to first pre-process the received signal, including filtering, denoising, and amplitude normalization. The goal of this step is to reduce noise interference and amplitude fluctuations during the propagation process, so that the signal has stable characteristics to facilitate the precise execution of the subsequent demodulation process. During the demodulation process, the signal receiving part reversely executes the dynamic modulation process used to generate the modulated signal. The time oscillation term, phase change term, and nonlinear amplitude correction term contained in the modulated signal formula need to be reversed one by one. The first step of demodulation is to extract its reference frequency from the received signal. The reference frequency is the core reference of the demodulation process. By comparing the phase information of the signal, we can identify the information carried by the dynamic modulation characteristics of the signal. The phase information of the signal is determined by the phase change function Indicates that its dynamic changes reflect the cumulative effect of the temperature and medium characteristics on the signal propagation path. In the demodulation process, the propagation distance can be extracted by inverting the phase characteristics of the received signal. and ambient temperature This step uses the quantitative relationship between phase change, propagation path and temperature, combined with the inverse calculation algorithm, to restore the specific values ​​of downhole environmental parameters. In addition, the demodulation process also includes correction and normalization of the signal amplitude. The amplitude of the received signal contains the wireless drilling pulse signal The intensity distribution of the received signal and the superposition of the nonlinear amplitude correction term. Through amplitude normalization, the energy distribution in the received signal can be readjusted to the standard state to eliminate the energy loss on the propagation path and the amplitude distortion caused by the medium change. At the same time, the inverse operation of the logarithmic correction term restores the mud flow density. The nonlinear relationship between the dynamic modulation term and the signal amplitude can further improve the demodulation accuracy. The reverse demodulation of the signal needs to combine time domain and frequency domain analysis to extract the information carried by the dynamic modulation characteristics through the decomposition of the signal spectrum. This information is usually related to dynamic parameters such as environmental vibration and pressure fluctuation, and is an important part of the demodulated output signal. and phase characteristics The demodulated signal can accurately reflect the real-time dynamic state of the well through the joint solution of the multi-level demodulation process. Finally, after multi-level demodulation processing, the received signal is restored to the demodulated output signal, which contains complete information on the physical parameters of the downhole environment, such as temperature, pressure, vibration, etc. In a high temperature environment, due to signal loss and interference in the propagation path, the demodulation process needs to ensure the integrity and accuracy of the signal through nonlinear correction, dynamic inverse operation, and frequency and phase reconstruction. By reversely executing the modulation process, the signal receiving part can not only restore the original information, but also effectively compensate for the interference in the propagation process, thereby ensuring that the downhole information can be transmitted to the ground without error, providing reliable guarantee for real-time monitoring of drilling operations.

[0042] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wireless pulse signal transmission system for drilling under high temperature conditions, characterized in that: The system comprises: a signal generating part, a signal transmitting part and a signal receiving part; the signal generating part is used to sense the change of temperature, pressure or vibration of the downhole environment through a piezoelectric crystal, generate an initial electrical signal, and convert the initial electrical signal into a pressure wave in the mud flow through an electromechanical device to form a mechanical signal, and the mechanical signal is captured by a sensor and reconverted into an initial pulse signal in the form of an electrical signal; the signal transmitting part is used to perform mud pressure modulation on the initial pulse signal by controlling the density of the mud flow, generate a wireless while-drilling pulse signal, and capture the phase change of the wireless while-drilling pulse signal during the propagation process to obtain a phase change function; based on the phase change function, perform nonlinear correction to obtain a correction result; based on the correction result, perform signal coding modulation to obtain a modulated signal; and send the modulated signal to a remote signal receiving part; the signal receiving part is used to receive the modulated signal and perform signal demodulation to obtain a demodulated output signal.

2. The wireless pulse signal transmission system for drilling under high temperature conditions as claimed in claim 1, characterized in that: The signal generating part places a piezoelectric crystal inside the drilling tool. When the temperature, pressure or vibration in the downhole environment changes, an initial electrical signal is generated at both ends of the piezoelectric crystal through the piezoelectric effect. The material of the piezoelectric crystal is lanthanum-modified lead zirconate titanate. The inside of the drilling tool is filled with mud flow. The electrical signal generated by the piezoelectric crystal drives the electromechanical device to change the flow state of the mud flow through coupling with the electromechanical device, and converts the initial electrical signal into a pressure wave in the mud flow to form a mechanical signal. The electromechanical device is an electromechanical pulser. The sensor is also placed directly inside the drilling tool, and through direct contact with the mud flow, it senses the change in the pressure wave and converts the mechanical signal back into an initial pulse signal in the form of an electrical signal.

3. The wireless pulse signal transmission system while drilling under high temperature conditions as claimed in claim 2, characterized in that: The initial electrical signal is expressed using the following formula: ； in, The piezoelectric crystal is at a temperature of When , the initial electrical signal generated; The piezoelectric crystal is at standard temperature The reference output voltage when is the thermal activation energy of the material of the piezoelectric crystal; is the Boltzmann constant; is temperature; : Temperature quadratic coefficient, which is the preset value; is the oscillation reference frequency of the piezoelectric crystal; For time.

4. The wireless pulse signal transmission system while drilling under high temperature conditions as claimed in claim 3, characterized in that: The mechanical signal is expressed using the following formula: ； in, The radial distance from the inside of the drilling tool to the axis is , the distance along the axial direction is , the temperature is When the mechanical signal is formed; is the longitudinal piezoelectric coefficient of the piezoelectric crystal; is the characteristic influence radius of the piezoelectric crystal; is the effective length of the piezoelectric crystal; is the elastic modulus of the piezoelectric crystal at standard temperature; For temperature The elastic modulus at ; is Poisson’s ratio; is the boundary effect coefficient, which is the preset value; It is the maximum distance from the outer surface of the drilling tool in the axial direction.

5. The wireless pulse signal transmission system while drilling under high temperature conditions as claimed in claim 4, characterized in that: The initial pulse signal is expressed using the following formula: ； in, is the initial pulse signal; is the temperature attenuation coefficient, which is the preset value; is a preset first mechanical-electrical conversion efficiency coefficient; is the signal angular frequency, .

6. The wireless pulse signal transmission system for drilling under high temperature conditions as claimed in claim 5, characterized in that: The wireless drilling pulse signal is expressed using the following formula: ； in, The propagation distance is time Wireless drilling pulse signal at the same time; is a preset second mechanical-electrical conversion efficiency coefficient; is the mud flow density at standard temperature; For temperature The mud flow density at ; is the pressure wave propagation attenuation coefficient, which is the set value; is the modulation frequency; is the modulation phase; is the modulation amplitude factor, is the set value; is the thermal expansion coefficient of the mud flow.

7. The wireless pulse signal transmission system while drilling under high temperature conditions as claimed in claim 6, characterized in that: The phase change function is expressed using the following formula: ； in, For temperature The wavelength of the wireless while drilling pulse signal; is the temperature phase coupling coefficient, is the set value; based on the phase change function, the nonlinear correction is performed through the following formula to obtain the correction result : ； in, is the nonlinear correction coefficient, is the set value; is the universal gas constant.

8. The wireless pulse signal transmission system while drilling under high temperature conditions as claimed in claim 7, characterized in that: The modulation signal is expressed by the following formula: ； in, is the average density of the mud flow.

9. The wireless pulse signal transmission system while drilling under high temperature conditions as claimed in claim 8, characterized in that: After receiving the modulated signal, the signal receiving part performs the inverse process of signal modulation, performs signal demodulation, and obtains a demodulated output signal.

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