Real-time monitoring system for borehole bottom pressure

Abstract

This invention relates to the field of coal mining technology and discloses a real-time borehole pressure monitoring system, comprising a housing, a data acquisition module, an ultrasonic transmitting module, a data receiving module, and a data processing module. The data acquisition module and the ultrasonic transmitting module are housed within a cavity of the housing. The data acquisition module acquires the actual pressure at the bottom of the borehole and converts it into a digitally encoded signal. The ultrasonic transmitting module modulates the digitally encoded signal to output an ultrasonic signal. The data receiving module is connected to the ultrasonic transmitting module via a fracturing rod and / or fracturing fluid, and demodulates the ultrasonic signal to output a demodulated signal. The data processing module processes the demodulated signal to output a data frame. This invention's monitoring system requires no cables, has strong anti-interference capabilities, and enables stable long-distance signal transmission.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a real-time monitoring system for borehole pressure. Background Technology

[0002] Directional long-bore hydraulic fracturing technology is widely used in coal mine rockburst prevention, roof control, and coalbed methane extraction projects. The bottom-hole pressure during fracturing is a key parameter reflecting the initiation, propagation, and closure behavior of fractures, and is of great significance for evaluating fracturing effectiveness and optimizing the process.

[0003] Although some research has been conducted in the field of hydraulic fracturing monitoring, existing technologies still have significant shortcomings in real-time acquisition of bottom hole pressure in directional long-distance boreholes. Specifically: (1) Wired transmission has poor reliability and is not suitable for long-distance directional drilling.

[0004] Currently, bottom hole pressure monitoring mostly uses cable transmission. However, in actual engineering projects, borehole lengths often exceed 500 m, and can even reach 1000 m. Cables are prone to stretching, wear, and even breakage. During directional drilling and fracturing, cables are susceptible to entanglement and jamming. Furthermore, in high-pressure fluid environments, cable sealing is difficult, easily leading to water ingress and failure. Therefore, wired transmission methods are insufficient to meet the stable monitoring requirements under long-distance, high-intensity construction conditions.

[0005] (2) Radio electromagnetic transmission technology is basically ineffective in underground environments.

[0006] Some studies have attempted to use radio or electromagnetic waves for data transmission, but due to the strong absorption and scattering of electromagnetic waves by coal seams and surrounding rocks, the high conductivity of the strata, and the significant signal attenuation, the transmission distance is extremely limited (usually only a few meters to tens of meters), making it difficult to apply radio transmission methods to deep drilling environments and thus unable to achieve effective communication.

[0007] (3) The pressure at the bottom of the hole cannot be obtained directly, and the monitoring data is seriously distorted.

[0008] In engineering practice, orifice pressure is often used to represent bottom pressure, but this method has significant errors. Specifically, these errors include: pressure attenuation along the pipe due to frictional losses; pressure distribution affected by hydrostatic pressure and local resistance; and complex pressure fluctuations caused by changes in flow regime during fracturing. Therefore, orifice pressure cannot accurately reflect the stress state at the bottom of the hole, severely impacting the evaluation of fracturing effectiveness and parameter optimization.

[0009] (4) The existing monitoring system lacks real-time performance and anti-interference capabilities.

[0010] During hydraulic fracturing, there is intense mechanical vibration and fluid impact, resulting in significant electromagnetic and fluid noise. Existing monitoring systems generally suffer from large data transmission delays and signal distortion due to interference, making it difficult to achieve continuous and stable real-time monitoring.

[0011] (5) Lack of highly reliable transmission mechanisms suitable for complex environments.

[0012] Existing technologies have not yet developed mature solutions suitable for the following conditions: high pressure (>30 MPa), high water environment, long distance (>1000 m), and dynamic monitoring during drilling or fracturing. In particular, effective technical means are still lacking in signal transmission mechanisms under the coupling environment of solid drill pipe and fluid medium.

[0013] (6) The monitoring system has low integration and poor engineering adaptability.

[0014] Existing devices are mostly experimental equipment, which have problems such as complex structure, large size, and difficulty in integration into the borehole. They are difficult to install on site, have poor engineering promotion, and cannot meet the actual construction needs of underground coal mines.

[0015] In summary, existing technologies for monitoring bottom pressure in long-distance directional hydraulic fracturing boreholes still suffer from problems such as unreliable transmission methods, severe data distortion, insufficient real-time performance, and poor environmental adaptability, failing to meet the application requirements under complex engineering conditions. Therefore, there is an urgent need to develop a real-time borehole pressure monitoring system that requires no cables, has strong anti-interference capabilities, and can achieve stable long-distance transmission. Summary of the Invention

[0016] The present invention aims to at least solve one of the technical problems existing in related technologies. To this end, the present invention provides a real-time borehole pressure monitoring system that requires no cables, has strong anti-interference capabilities, and can achieve stable signal transmission over long distances.

[0017] This invention provides a real-time monitoring system for bottom hole pressure, comprising: The outer shell has an internal cavity for installation at the bottom of the drilled hole; The data acquisition module includes a pressure acquisition unit, a data acquisition unit, and a data encoding unit, all installed in the receiving cavity. The pressure acquisition unit is located at the end of the receiving cavity near the bottom of the borehole and is used to acquire the actual pressure during the fracturing process. The first input terminal of the data acquisition unit is connected to the pressure acquisition unit and is used to acquire the actual pressure at a preset frequency, and to filter, denoise, and perform analog-to-digital conversion on the actual pressure to output a digital signal with a pressure identifier. The input terminal of the data encoding unit is connected to the output terminal of the data acquisition unit and is used to convert the digital signal into a digitally encoded signal. An ultrasonic transmitting module includes a signal modulation unit and an ultrasonic transmitting unit, both installed in the receiving cavity; the input terminal of the signal modulation unit is connected to the output terminal of the data encoding unit, and is used to modulate the digitally encoded signal into an ultrasonic carrier signal with a pressure indicator; the input terminal of the ultrasonic transmitting unit is connected to the output terminal of the signal modulation unit, and is used to convert the ultrasonic carrier signal into an ultrasonic signal. The data receiving module includes an ultrasonic receiving unit, a signal processing unit, and a demodulator. The input of the ultrasonic receiving unit is connected to the output of the ultrasonic transmitting unit via a fracturing rod and / or fracturing fluid to receive the ultrasonic signal. The input of the signal processing unit is connected to the output of the ultrasonic receiving unit to process the ultrasonic signal. The input of the demodulator is connected to the output of the signal processing unit to demodulate the processed ultrasonic signal and output a demodulated signal. The data processing module includes a data processing unit; the input terminal of the data processing unit is connected to the output terminal of the demodulator, and is used to process the demodulated signal and output a data frame with a pressure identifier.

[0018] According to the real-time monitoring system for bottom hole pressure provided by the present invention, the data acquisition module further includes: A temperature acquisition unit is arranged in the receiving cavity and located on one side of the pressure acquisition unit; the temperature acquisition unit is used to acquire the actual temperature during the fracturing process; the second input terminal of the data acquisition unit is connected to the temperature acquisition unit and is used to acquire the actual temperature at a preset frequency, and to filter, denoise and convert the actual temperature to digital signal with temperature label.

[0019] According to the real-time monitoring system for bottom hole pressure provided by the present invention, the signal processing unit includes: A preamplifier, the input of which is connected to the output of the ultrasonic receiving unit, is used to initially amplify the ultrasonic signal; A bandpass filter, wherein the input terminal of the bandpass filter is connected to the output terminal of the preamplifier, and the output terminal of the bandpass filter is connected to the input terminal of the demodulator.

[0020] The real-time monitoring system for bottom hole pressure provided by the present invention further includes, in the signal processing unit: An automatic gain amplifier is provided, the input of which is connected to the output of the bandpass filter, and the output of which is connected to the input of the demodulator.

[0021] According to the real-time monitoring system for bottom hole pressure provided by the present invention, the data receiving module further includes: A data verification circuit, wherein the input terminal of the data verification circuit is connected to the output terminal of the demodulator, and the output terminal of the data verification circuit is connected to the input terminal of the data processing unit, and the data verification circuit is configured as follows: Used to verify the demodulated signal and detect whether bit errors occur during transmission; In the absence of bit errors, the demodulated signal is sent to the data processing unit. In the event of a bit error, an alarm signal will be output.

[0022] The real-time monitoring system for bottom hole pressure provided by the present invention further includes: A power module, housed in the receiving cavity, is used to supply power to the data acquisition module and the ultrasonic transmitting module.

[0023] According to the real-time monitoring system for bottom hole pressure provided by the present invention, the pressure acquisition unit, the data acquisition unit, the data encoding unit, the signal modulation unit, the ultrasonic transmitting unit, and the power supply module are arranged sequentially along the axial direction of the housing away from the bottom hole.

[0024] According to the real-time monitoring system for bottom hole pressure provided by the present invention, the data processing module further includes: The display unit has its first input terminal connected to the first output terminal of the data processing unit for displaying data.

[0025] According to the real-time monitoring system for bottom hole pressure provided by the present invention, the data processing module further includes: A data storage unit, wherein the first input terminal of the data storage unit is connected to the second output terminal of the data processing unit, is used to store data.

[0026] According to the real-time monitoring system for bottom hole pressure provided by the present invention, the data processing module further includes: A fracturing curve analysis and early warning unit is provided, wherein the input terminal of the fracturing curve analysis and early warning unit is connected to the third output terminal of the data processing unit, and the first output terminal of the fracturing curve analysis and early warning unit is connected to the second input terminal of the display unit; the fracturing curve analysis and early warning unit is configured as follows: The data processing unit analyzes the data frame output by the data processing unit, and outputs a warning signal if the analysis result does not meet the preset requirements. The display unit then displays the warning information based on the warning signal.

[0027] The real-time monitoring system for bottom hole pressure provided by this invention enables in-situ real-time acquisition of bottom hole pressure during hydraulic fracturing by arranging pressure acquisition units at the bottom of the hole. This avoids the error problems caused by the traditional indirect calculation using orifice pressure, effectively eliminates the influence of factors such as pipeline friction and liquid column pressure, and significantly improves the authenticity and accuracy of pressure data.

[0028] Using ultrasound as the information transmission carrier enables data propagation in the fracturing rod and fracturing fluid: eliminating the need for cable laying and avoiding problems such as cable breakage and entanglement; improving the reliability of the system in long-distance drilling; suitable for continuous operation under complex working conditions; thus solving the problem that traditional wired monitoring methods are difficult to adapt to deep hole environments.

[0029] By constructing solid transmission paths, liquid transmission paths, or solid-liquid coupled transmission paths for fracturing rods, signal attenuation can be effectively reduced, achieving a stable transmission distance of over 1000 m; high signal integrity and low bit error rate; meeting the actual needs of directional long borehole fracturing projects.

[0030] By employing modulation coding (such as FSK / ASK) and signal filtering processing techniques, the system possesses strong anti-interference capabilities, resists mechanical vibration interference, resists fluid impact noise, resists electromagnetic environment influences, and ensures stable data transmission even under high pressure and high noise conditions.

[0031] Furthermore, by setting up a display unit, continuous real-time transmission and display of bottom hole pressure can be achieved, reflecting the crack initiation, propagation and closure process in real time; supporting dynamic adjustment of fracturing parameters (displacement, pressure, etc.); improving the controllability and safety of fracturing operations; and providing key data support for refined fracturing.

[0032] The device integrates pressure acquisition unit, data acquisition unit, and ultrasonic transmission unit into the bottom hole device, which is small in size, easy to install, has good sealing performance, is suitable for high pressure and high water environment, is compatible with existing drilling construction technology, and has good field application and promotion capabilities. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention and are not considered as limitations on this application. Moreover, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0034] Figure 1 This is one of the schematic structural diagrams of the real-time monitoring system for bottom hole pressure provided by the present invention.

[0035] Figure 2This is a schematic structural diagram of the data structure module of the real-time monitoring system for borehole pressure provided by the present invention.

[0036] Figure 3 This is the second schematic structural diagram of the real-time monitoring system for borehole pressure provided by the present invention.

[0037] Figure 4 This is the third schematic structural diagram of the real-time monitoring system for borehole pressure provided by the present invention.

[0038] Figure 5 This is the fourth schematic structural diagram of the real-time monitoring system for borehole pressure provided by the present invention.

[0039] Figure label: 100. Outer shell; 200. Data acquisition module; 210. Pressure acquisition unit; 220. Data acquisition unit; 230. Data encoding unit; 240. Temperature acquisition unit; 300. Ultrasonic transmitting module; 310. Signal modulation unit; 320. Ultrasonic transmitting unit; 400. Data receiving module; 500. Data processing module; 600. Power supply module. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0041] The specific terms used in this specification are for illustrative purposes only and are not intended to limit the illustrated embodiments. For example, expressions such as "same" and "identical" not only indicate a strictly identical state, but also indicate a state with tolerances or differences in the degree of functionality. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "side by side," "perpendicular," "centered on," "concentric," or "coaxial" not only strictly indicate such an arrangement, but also indicate a state of relative displacement by tolerances or angles or distances with the same degree of functionality.

[0042] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0043] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "multiple" means two or more. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified. In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, B1 and / or B2 can represent: B1 existing alone, B1 and B2 existing simultaneously, and B2 existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] The following is combined Figures 1 to 5 The structure and working process of the real-time borehole pressure monitoring system provided by the present invention are described.

[0046] like Figures 1 to 5 As shown, a specific embodiment of the present invention provides a real-time monitoring system for bottom hole pressure, which includes a housing 100, a data acquisition module 200, an ultrasonic transmitting module 300, a data receiving module 400, and a data processing module 500.

[0047] The housing 100 has an internal receiving cavity for installation at the bottom of the borehole. Typically, the housing 100 can be detachably connected to the fracturing tubing via threads or other means. This connection method allows the housing 100, containing the monitoring system, to be easily installed or removed from the end of the fracturing tubing during hydraulic fracturing operations and placed along with it at the bottom of the borehole. Placing the monitoring system directly at the bottom of the borehole enables in-situ acquisition of actual pressure during fracturing, thereby avoiding the difference between the orifice pressure and the bottom pressure caused by factors such as tubing friction loss and hydrostatic pressure of the hydraulic column, improving the authenticity and accuracy of the monitoring data.

[0048] The data acquisition module 200 includes a pressure acquisition unit 210, a data acquisition unit 220, and a data encoding unit 230, all installed in the containment cavity. The pressure acquisition unit 210 is located at the end of the containment cavity near the bottom of the borehole and is used to acquire the actual pressure during the fracturing process. The first input terminal of the data acquisition unit 220 is connected to the pressure acquisition unit 210 and is used to acquire the actual pressure at a preset frequency, and to filter, denoise, and perform analog-to-digital conversion on the actual pressure to output a digital signal with a pressure identifier. The filtering and denoising processes can suppress the noise interference caused by the strong mechanical vibration and fluid impact during hydraulic fracturing, ensuring the quality of the original signal. The input terminal of the data encoding unit 230 is connected to the output terminal of the data acquisition unit 220 and is used to convert the digital signal into a digitally encoded signal, laying the foundation for subsequent modulation and reliable transmission.

[0049] The ultrasonic transmitting module 300 includes a signal modulation unit 310 and an ultrasonic transmitting unit 320, both installed in the receiving cavity. The input terminal of the signal modulation unit 310 is connected to the output terminal of the data encoding unit 230, and is used to modulate the digitally encoded signal into an ultrasonic carrier signal with a pressure indicator. The input terminal of the ultrasonic transmitting unit 320 is connected to the output terminal of the signal modulation unit 310, and is used to convert the ultrasonic carrier signal into an ultrasonic signal. By using ultrasound as the information carrier, the traditional wired cable transmission method is replaced, thus solving the problems of poor reliability caused by cables under long-distance, high-intensity construction conditions, such as tensile stress, wear, breakage, and sealing failure, and improving the system's applicability under complex working conditions.

[0050] The data receiving module 400 includes an ultrasonic receiving unit, a signal processing unit, and a demodulator. The input of the ultrasonic receiving unit is connected to the output of the ultrasonic transmitting unit 320 via a fracturing rod and / or fracturing fluid to receive ultrasonic signals. By utilizing the fracturing rod (solid) and / or fracturing fluid (fluid) as the signal transmission medium, solid transmission paths, liquid transmission paths, or solid-liquid coupling transmission paths can be constructed. This addresses the strong absorption and scattering of electromagnetic waves by coal seams and surrounding rock, overcoming the shortcomings of radio electromagnetic transmission technology in underground environments, such as severe signal attenuation and limited transmission distance, thus achieving stable long-distance data transmission. The input of the signal processing unit is connected to the output of the ultrasonic receiving unit to process the ultrasonic signals. The input of the demodulator is connected to the output of the signal processing unit to demodulate the processed ultrasonic signals to output a demodulated signal.

[0051] The data processing module 500 includes a data processing unit; the input of the data processing unit is connected to the output of the demodulator, and it is used to process the demodulated signal and output a data frame with a pressure identifier. By processing the demodulated signal in real time and outputting the data frame, the bottom hole pressure information can be clearly and continuously presented to the operator, realizing real-time monitoring of the fracturing process and providing data support for the immediate evaluation of fracturing effect and dynamic optimization of process parameters.

[0052] The real-time borehole pressure monitoring system of this embodiment is used in boreholes with a drilling depth greater than 1000 meters and a pressure of 0 MPa to 50 MPa, with a sampling frequency of not less than 10 Hz, an operating temperature of -20℃ to 80℃, a signal transmission delay of not more than 2 seconds, and a signal error rate of less than 1%.

[0053] Optionally, the modulation method of the signal modulation unit 310 is frequency shift keying (FSK) or amplitude shift keying (ASK).

[0054] It should be noted that this invention is not only applicable to directional hydraulic fracturing in coal mines, but can also be extended to coalbed methane extraction, deep rock mass fracturing and modification, geothermal development, and shale gas fracturing. The monitoring system of this invention has strong versatility and engineering application value.

[0055] The working principle of this embodiment is as follows: the pressure acquisition unit 210 acquires the actual pressure at the bottom of the borehole in real time. The data acquisition unit 220 processes the actual pressure and converts it into a digital signal. The digital signal is modulated by the data encoding unit 230 and the signal modulation unit, and then converted into an ultrasonic carrier signal that can be recognized by the ultrasonic transmitting unit 320. Finally, the ultrasonic transmitting unit 320 converts the ultrasonic carrier signal into an ultrasonic signal with a specific frequency or amplitude. The ultrasonic signal is transmitted to the ultrasonic receiving unit located at the borehole opening through the fracturing rod and / or fracturing fluid. The received signal is processed by the signal processing unit and demodulated by the demodulator, and finally a demodulated signal is formed and transmitted to the data processing unit. The data processing unit then sends the information to at least one of the display unit, data storage unit, or fracturing curve analysis and early warning unit.

[0056] Optionally, the pressure acquisition unit 210 is a pressure sensor used to acquire the actual pressure at the bottom of the borehole in real time.

[0057] Optionally, the ultrasonic transmitting unit 320 is an ultrasonic transmitting transducer.

[0058] Optionally, the ultrasonic receiving unit is an ultrasonic receiving transducer.

[0059] In some embodiments of the present invention, the data acquisition module 200 further includes a temperature acquisition unit 240; the temperature acquisition unit 240 is arranged in the receiving cavity and located on one side of the pressure acquisition unit 210; the temperature acquisition unit 240 is used to acquire the actual temperature during the fracturing process, and the second input terminal of the data acquisition unit 220 is connected to the temperature acquisition unit 240, used to acquire the actual temperature at a preset frequency, and to filter, denoise, and perform analog-to-digital conversion on the actual temperature to output a digital signal with a temperature label. In the hydraulic fracturing environment, temperature changes will affect the measurement accuracy of the pressure acquisition unit 210. By synchronously acquiring the actual temperature, temperature information at a time point corresponding to the pressure data can be obtained.

[0060] Data encoding unit 230 converts the temperature-labeled digital signal into a digitally encoded signal. Signal modulation unit 310 modulates the temperature-labeled digitally encoded signal into a temperature-labeled ultrasonic carrier signal; ultrasonic transmitting unit 320 converts the temperature-labeled ultrasonic carrier signal into a temperature-labeled ultrasonic signal. The temperature-labeled ultrasonic signal is received by the ultrasonic receiving unit, processed by the signal processing unit, and finally demodulated by the demodulator into a temperature-labeled demodulated signal. Finally, data processing module 500 uses the temperature-labeled demodulated signal to perform temperature compensation on the corresponding pressure demodulated signal to output a more accurate pressure data frame. By performing temperature compensation on the pressure signal, the error introduced by temperature drift in the pressure measurement results can be eliminated, thereby further improving the accuracy of pressure monitoring.

[0061] It should be noted that the actual pressure and temperature collected at the same time point correspond to the actual pressure.

[0062] like Figure 2 As shown, in some embodiments of the present invention, the signal processing unit includes a preamplifier and a bandpass filter. The input of the preamplifier is connected to the output of the ultrasonic receiving unit for preliminary amplification of the ultrasonic signal. Since the ultrasonic signal attenuates after long-distance transmission through the fracturing rod and / or fracturing fluid, the preamplifier amplifies the received weak signal, increasing the signal level and thus improving the signal-to-noise ratio, laying the foundation for subsequent signal processing. The input of the bandpass filter is connected to the output of the preamplifier, and the output of the bandpass filter is connected to the input of the demodulator. Even after amplification, the signal may still contain interference noise generated by mechanical vibration, fluid impact, etc. The bandpass filter allows ultrasonic carrier signals within a preset frequency range to pass through while filtering out noise signals outside the frequency band, further improving the signal-to-noise ratio, enhancing the system's anti-interference capability, ensuring the signal quality input to the demodulator, and reducing the data transmission error rate.

[0063] like Figure 2 As shown, in some embodiments of the present invention, in addition to a preamplifier and a bandpass filter, the signal processing unit also includes an automatic gain amplifier. The input terminal of the automatic gain amplifier is connected to the output terminal of the bandpass filter, and the output terminal of the automatic gain amplifier is connected to the input terminal of the demodulator.

[0064] During fracturing operations, the intensity of the received ultrasonic signal fluctuates due to vibrations in the fracturing rod, changes in the flow pattern of the fracturing fluid, and dynamic factors along the transmission path. Both excessively weak and excessively strong signals can affect the normal operation of the subsequent demodulator. An automatic gain amplifier (AGA) automatically adjusts its gain based on the amplitude of the input signal. When the signal from the bandpass filter is weak, the gain is increased; when the signal is strong, the gain is decreased. In this way, the AGA outputs a relatively stable signal to the demodulator, keeping the signal input to the demodulator within an appropriate level range. This improves the system's adaptability to dynamic signal changes and ensures the stability and reliability of the demodulation process.

[0065] In some embodiments of the present invention, in addition to the ultrasonic receiving unit, signal processing unit, and demodulator, the data receiving module 400 also includes a data verification circuit. The input terminal of the data verification circuit is connected to the output terminal of the demodulator, and the output terminal of the data verification circuit is connected to the input terminal of the data processing unit. The data verification circuit is configured to: verify the demodulated signal to detect whether bit errors occur during transmission; if no bit errors occur, send the demodulated signal to the data processing unit; and if bit errors occur, output an alarm signal.

[0066] After signals travel long distances through complex media, they may be interfered with by various noise sources in the downhole environment, leading to errors in the data transmission, i.e., bit errors. The data verification circuit is designed to verify the integrity and accuracy of the demodulated data. In the absence of bit errors, the demodulated signal is sent to the data processing unit, ensuring that the data entering the final data processing stage is reliable and avoiding incorrect judgments of the bottom hole pressure status due to the use of corrupted data. In the event of bit errors, an alarm signal is output. This alarm signal can be used to prompt the data processing unit to discard the erroneous data frame or to mark it in the data record, thereby preventing erroneous data from contaminating the fracturing curve analysis, display, and early warning results, and improving the reliability of the entire monitoring system's output.

[0067] like Figure 3 and Figure 4 As shown, in some embodiments of the present invention, the real-time borehole pressure monitoring system further includes a power supply module 600. The power supply module 600 is housed in a receiving cavity and is used to supply power to the data acquisition module 200 and the ultrasonic transmitting module 300. Specifically, the power supply module 600 is connected to the pressure acquisition unit 210, the data acquisition unit 220, the data encoding unit 230, the signal modulation unit 310, and the ultrasonic transmitting unit 320, and is used to supply power to them.

[0068] Since this embodiment uses wireless transmission, the electronic modules inside the housing 100 at the bottom of the hole cannot obtain power from the ground through cables. By setting up an independent power module 600 and integrating it into the housing cavity, the measurement and transmission part at the bottom of the hole becomes an independent system that is free from dependence on external power cables.

[0069] Optionally, the power module 600 is a battery or a hydroelectric power generation device. Preferably, the power module 600 is a battery.

[0070] Optionally, the pressure acquisition unit 210, data acquisition unit 220, data encoding unit 230, signal modulation unit 310, ultrasonic transmitting unit 320, and power module 600 are arranged sequentially along the axial direction of the housing 100 away from the bottom of the hole. This layout allows each functional module to be compactly integrated into a cylindrical housing 100, resulting in a simple structure, high space utilization, easy encapsulation and sealing, and ensuring that the overall dimensions of the hole bottom device meet the requirements of drilling operations, thus improving the system's engineering adaptability.

[0071] Optionally, the temperature acquisition unit 240 is located between the pressure acquisition unit 210 and the data acquisition unit 220.

[0072] In some embodiments of the present invention, in addition to the data processing unit, the data processing module 500 also includes a display unit. A first input terminal of the display unit is connected to a first output terminal of the data processing unit for displaying data.

[0073] By setting up a display unit, the data frames with pressure indicators output by the data processing unit can be presented to the field operators in real time in a visual form (such as digital readings, pressure-time curves, etc.). This transforms abstract data into intuitive graphical information, directly solving the problem of insufficient real-time performance of existing pressure monitoring. Operators can observe the real changes in bottom hole pressure instantly and continuously, thereby accurately judging the initiation, propagation, and closure of fractures. Based on this real and real-time bottom hole pressure information, operators can dynamically adjust fracturing parameters (such as displacement and pump pressure), avoiding the blindness caused by relying on orifice pressure estimation in the past, and improving the controllability and safety of the fracturing operation process.

[0074] In some embodiments of the present invention, in addition to the data processing unit, the data processing module 500 also includes a data storage unit. A first input terminal of the data storage unit is connected to a second output terminal of the data processing unit, and is used to store data.

[0075] By storing the data frames containing bottom hole pressure information output by the data processing unit, data traceability and in-depth analysis after fracturing operations can be made possible. The stored historical data can be used to build a fracturing engineering database. By comparing pressure response curves under different operating conditions, objective evidence can be provided for optimizing subsequent fracturing operations, evaluating fracturing effects, and adjusting process parameters. In addition, this data storage function also provides data backup for the entire monitoring process, ensuring the integrity and traceability of the original monitoring data in the event of real-time display interruption or when data verification is required.

[0076] In some embodiments of the present invention, in addition to the data processing unit and the display unit, the data processing module 500 also includes a data storage unit. A first input terminal of the display unit is connected to a first output terminal of the data processing unit for displaying data. A first input terminal of the data storage unit is connected to a second output terminal of the data processing unit for storing data.

[0077] This configuration enables the data processing module 500 to simultaneously provide real-time display and data archiving capabilities. Operators obtain immediate information through the display unit for on-site decision-making, while the data storage unit saves all monitoring data. This parallel processing approach not only meets the real-time monitoring needs during fracturing operations but also ensures that complete and original data records are preserved for subsequent comprehensive analysis, effect evaluation, and process optimization.

[0078] In some embodiments of the invention, in addition to the data processing unit and the display unit, the data processing module 500 also includes a fracturing curve analysis and early warning unit. The input terminal of the fracturing curve analysis and early warning unit is connected to the third output terminal of the data processing unit, and the first output terminal of the fracturing curve analysis and early warning unit is connected to the second input terminal of the display unit; the fracturing curve analysis and early warning unit is configured as follows: This system analyzes the data frames output by the data processing unit. The analysis process includes identifying the rate of change, trend, and characteristic points of pressure data to determine the current fracturing operation status. If the analysis results do not meet preset requirements—for example, whether the pressure exceeds a preset safety threshold, whether the pressure drop rate indicates potential sand blockage, or whether the pressure curve shows abnormal fluctuations—an early warning signal is output, and the display unit displays the warning information based on the signal. Through automated real-time analysis and early warning, operators are freed from the task of continuously monitoring complex data, and potential construction risks or abnormal conditions are promptly alerted. This allows operators to take intervention measures earlier, such as adjusting pumping parameters or stopping operations, thereby improving the safety of fracturing operations and providing technical support to avoid costly construction accidents.

[0079] Optionally, the fracturing curve analysis and early warning unit may analyze data frames in at least one of the following ways: amplitude feature analysis, gradient feature analysis, or morphological feature analysis.

[0080] Amplitude characteristic analysis compares the real-time pressure value contained in the data frame with one or more preset pressure thresholds. These preset requirements may include an upper pressure limit (such as a construction safety pressure limit) and a lower pressure limit (such as the minimum pressure required to maintain crack opening). When the real-time pressure value exceeds this preset range, the analysis result indicates that the requirements are not met. This analysis method can directly monitor whether the construction pressure is within a safe and effective range, providing early warning to prevent equipment damage or fracturing failure caused by overpressure.

[0081] Gradient feature analysis calculates the rate of pressure change over time based on continuously received data frames. Preset requirements allow setting thresholds for this rate of change. For example, when the pressure drop rate exceeds a certain preset value, it may indicate a sudden event such as sand blockage; when an inflection point occurs where the pressure rise rate slows down, it can be identified as a formation fracture point. By analyzing the slope of the pressure curve, event nodes and process anomalies in the fracturing process can be identified, thus providing a deeper basis for on-site decision-making.

[0082] Morphological feature analysis involves comparing a real-time pressure curve segment, consisting of a series of continuous data frames, with a standard fracturing pressure curve model stored within the cell. The preset requirement is that the similarity or deviation between the real-time curve and the standard model does not exceed the allowable range. When the real-time curve exhibits abnormal fluctuations or shapes outside the standard model, the analysis result is considered unsatisfactory. This allows for a macroscopic understanding of whether the overall fracturing operation is progressing as expected, and identifies complex conditions that are difficult to determine through a single amplitude or gradient.

[0083] In some embodiments of the present invention, in addition to the data processing unit, display unit, and data storage unit, the data processing module 500 further includes a fracturing curve analysis and early warning unit. The input terminal of the fracturing curve analysis and early warning unit is connected to the third output terminal of the data processing unit, and the first output terminal of the fracturing curve analysis and early warning unit is connected to the second input terminal of the display unit; the second output terminal of the fracturing curve analysis and early warning unit is connected to the second input terminal of the data storage unit. The fracturing curve analysis and early warning unit is configured as follows: This unit is used to analyze the data frames output by the data processing unit. If the analysis results do not meet the preset requirements, it outputs a warning signal. The display unit displays the warning information based on the warning signal, and the data storage unit stores the warning event.

[0084] When an early warning occurs, the data storage unit records the type and time of the warning, along with key pressure data before and after the warning, forming a structured early warning log. This log provides a direct and clear chain of evidence for post-fracturing operations review and accident tracing, facilitating engineers' analysis of the causes of abnormal conditions and the development of corresponding improvement measures. In the long term, statistical analysis of accumulated early warning event data can uncover high-risk operating patterns under specific conditions, thereby providing reverse guidance and optimizing fracturing construction plans, and continuously improving the risk control capabilities of the entire system.

[0085] Example 1 This embodiment provides a real-time orifice bottom pressure monitoring system, including a housing 100, a data acquisition module 200, an ultrasonic transmitting module 300, a data receiving module 400, a data processing module 500, and a power supply module 600. The data acquisition module 200, ultrasonic transmitting module 300, and power supply module 600 are encapsulated within the housing 100 to form an orifice bottom device. The power supply module 600 is connected to the data acquisition module 200 and the ultrasonic transmitting module 300, and is used to supply power to them.

[0086] The data acquisition module 200 includes a pressure acquisition unit 210, a temperature acquisition unit 240, a data acquisition unit 220, and a data encoding unit 230. The pressure acquisition unit 210 is located at the end of the receiving cavity near the bottom of the borehole and is used to acquire the actual pressure during the fracturing process. The temperature acquisition unit 240 is located in the receiving cavity and to one side of the pressure acquisition unit 210; the temperature acquisition unit 240 is used to acquire the actual temperature during the fracturing process. The first input terminal of the data acquisition unit 220 is connected to the pressure acquisition unit 210 and is used to acquire the actual pressure at a preset frequency, and to filter, denoise, and perform analog-to-digital conversion on the actual pressure to output a digital signal with a pressure identifier. The second input terminal of the data acquisition unit 220 is connected to the temperature acquisition unit 240 and is used to acquire the actual temperature at a preset frequency, and to filter, denoise, and perform analog-to-digital conversion on the actual temperature to output a digital signal with a temperature identifier. The input terminal of the data encoding unit 230 is connected to the output terminal of the data acquisition unit 220 and is used to convert the digital signal into a digitally encoded signal.

[0087] The ultrasonic transmitting module 300 includes a signal modulation unit 310 and an ultrasonic transmitting unit 320. The input terminal of the signal modulation unit 310 is connected to the output terminal of the data encoding unit 230, and is used to modulate the digital encoded signal into an ultrasonic carrier signal; the input terminal of the ultrasonic transmitting unit 320 is connected to the output terminal of the signal modulation unit 310, and is used to convert the ultrasonic carrier signal into an ultrasonic signal.

[0088] The data receiving module 400 includes an ultrasonic receiving unit, a signal processing unit, a demodulator, and a data verification circuit. The signal processing unit includes a preamplifier, a bandpass filter, and an automatic gain amplifier. The input of the ultrasonic receiving unit is connected to the output of the ultrasonic transmitting unit 320 via a fracturing rod and / or fracturing fluid to receive ultrasonic signals. The input of the preamplifier is connected to the output of the ultrasonic receiving unit to initially amplify the ultrasonic signal. The input of the bandpass filter is connected to the output of the preamplifier, and the output of the bandpass filter is connected to the input of the automatic gain amplifier. The output of the automatic gain amplifier is connected to the input of the demodulator. The demodulator demodulates the ultrasonic signal output from the automatic gain amplifier to output a demodulated signal. The output of the demodulator is connected to the input of the data verification circuit, which is configured to: verify the demodulated signal and detect whether bit errors occur during transmission; send the demodulated signal to the data processing unit if no bit errors occur; and output an alarm signal if bit errors occur.

[0089] The data processing module 500 includes a data processing unit, a display unit, a data storage unit, and a fracturing curve analysis and early warning unit. The input terminal of the data processing unit is connected to the output terminal of the data verification circuit, used to process the demodulated signal and output a data frame. The first input terminal of the display unit is connected to the first output terminal of the data processing unit, used to display data. The first input terminal of the data storage unit is connected to the second output terminal of the data processing unit, used to store data. The input terminal of the fracturing curve analysis and early warning unit is connected to the third output terminal of the data processing unit, and the first output terminal of the fracturing curve analysis and early warning unit is connected to the second input terminal of the display unit. The fracturing curve analysis and early warning unit is configured to analyze the data frame output by the data processing unit, and output an early warning signal if the analysis result does not meet preset requirements; the display unit then displays early warning information based on the early warning signal.

[0090] Example 2 A directional long-bore hydraulic fracturing test was conducted in a coal mine, with a borehole length of 1200 m. The bottom-hole pressure real-time monitoring system provided in Example 1 was installed at the bottom of the borehole. The signal modulation unit 310 modulated the digital coded signal output by the data encoding unit 230 using frequency shift keying (FSK). The ultrasonic signal was transmitted through the fracturing rod to the ultrasonic receiving unit at the borehole opening, and then sequentially passed through the signal processing unit, demodulator, and data verification circuit before being transmitted to the data processing unit and finally displayed in real time by the display unit. Through analysis of real-time monitoring data and the fracturing model, the actual pressure curve showed a high degree of agreement with the expected fracturing behavior, with the error at key feature points being less than 5%.

[0091] Example 3 Unlike Example 2, Example 3 uses a fluid medium (e.g., fracturing fluid) as the propagation channel for ultrasonic signals. The analysis results show that the actual pressure curve and the theoretical pressure curve have a high degree of agreement under high-noise fracturing environment, and the error of key feature points is less than 5%, indicating that ultrasonic signals can still be transmitted stably.

[0092] Example 4 Unlike Example 2, this example uses both the fracturing rod and fracturing fluid as transmission channels for ultrasonic signals. In other words, the ultrasonic signal is transmitted to the ultrasonic receiving unit through both the fracturing rod and the fracturing fluid. The data processing module 500 selects the transmission path with better signal quality, thereby improving transmission stability and resistance to signal attenuation.

[0093] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A real-time monitoring system for bottom hole pressure, characterized in that, include: The outer casing (100) has an internal cavity for mounting at the bottom of a drilled hole; The data acquisition module (200) includes a pressure acquisition unit (210), a data acquisition unit (220), and a data encoding unit (230), all installed in the receiving cavity. The pressure acquisition unit (210) is located at the end of the receiving cavity near the bottom of the borehole and is used to acquire the actual pressure during the fracturing process. The first input terminal of the data acquisition unit (220) is connected to the pressure acquisition unit (210) and is used to acquire the actual pressure at a preset frequency, and to filter, denoise, and perform analog-to-digital conversion on the actual pressure to output a digital signal with a pressure identifier. The input terminal of the data encoding unit (230) is connected to the output terminal of the data acquisition unit (220) and is used to convert the digital signal into a digital encoded signal. An ultrasonic transmitting module (300) includes a signal modulation unit (310) and an ultrasonic transmitting unit (320) both installed in the receiving cavity; the input terminal of the signal modulation unit (310) is connected to the output terminal of the data encoding unit (230) for modulating the digital encoded signal into an ultrasonic carrier signal with a pressure indicator; the input terminal of the ultrasonic transmitting unit (320) is connected to the output terminal of the signal modulation unit (310) for converting the ultrasonic carrier signal into an ultrasonic signal. The data receiving module (400) includes an ultrasonic receiving unit, a signal processing unit, and a demodulator; the input end of the ultrasonic receiving unit is connected to the output end of the ultrasonic transmitting unit (320) via a fracturing rod and / or fracturing fluid, for receiving the ultrasonic signal; the input end of the signal processing unit is connected to the output end of the ultrasonic receiving unit, for processing the ultrasonic signal; the input end of the demodulator is connected to the output end of the signal processing unit, for demodulating the processed ultrasonic signal to output a demodulated signal. The data processing module (500) includes a data processing unit; the input end of the data processing unit is connected to the output end of the demodulator, and is used to process the demodulated signal and output a data frame with a pressure indicator.

2. The real-time monitoring system for hole bottom pressure according to claim 1, characterized in that, The data acquisition module (200) also includes: A temperature acquisition unit (240) is arranged in the receiving cavity and located on one side of the pressure acquisition unit (210); the temperature acquisition unit (240) is used to acquire the actual temperature during the fracturing process; the second input terminal of the data acquisition unit (220) is connected to the temperature acquisition unit (240) and is used to acquire the actual temperature at a preset frequency, and to filter, denoise and convert the actual temperature to digital signal with temperature label.

3. The real-time downhole pressure monitoring system of claim 1, wherein, The signal processing unit includes: A preamplifier, the input of which is connected to the output of the ultrasonic receiving unit, is used to initially amplify the ultrasonic signal; A bandpass filter, wherein the input terminal of the bandpass filter is connected to the output terminal of the preamplifier, and the output terminal of the bandpass filter is connected to the input terminal of the demodulator.

4. The real-time downhole pressure monitoring system of claim 3, wherein, The signal processing unit further includes: An automatic gain amplifier is provided, the input of which is connected to the output of the bandpass filter, and the output of which is connected to the input of the demodulator.

5. The real-time downhole pressure monitoring system of claim 1, wherein, The data receiving module (400) further includes: A data verification circuit, wherein the input terminal of the data verification circuit is connected to the output terminal of the demodulator, and the output terminal of the data verification circuit is connected to the input terminal of the data processing unit, and the data verification circuit is configured as follows: Used to verify the demodulated signal and detect whether bit errors occur during transmission; In the absence of bit errors, the demodulated signal is sent to the data processing unit. In the event of a bit error, an alarm signal will be output.

6. The real-time downhole pressure monitoring system of claim 1, wherein, Also includes: A power module (600) is housed in the receiving cavity and is used to supply power to the data acquisition module (200) and the ultrasonic transmitting module (300).

7. The real-time downhole pressure monitoring system of claim 6, wherein, The pressure acquisition unit (210), the data acquisition unit (220), the data encoding unit (230), the signal modulation unit (310), the ultrasonic transmitting unit (320), and the power module (600) are arranged sequentially along the axial direction of the outer shell (100) away from the bottom of the hole.

8. The real-time monitoring system of bottom hole pressure according to any one of claims 1 to 7, characterized in that, The data processing module (500) further includes: The display unit has its first input terminal connected to the first output terminal of the data processing unit for displaying data.

9. The real-time downhole pressure monitoring system of claim 8, wherein, The data processing module (500) further includes: A data storage unit, wherein the first input terminal of the data storage unit is connected to the second output terminal of the data processing unit, is used to store data.

10. The real-time downhole pressure monitoring system of claim 9, wherein, The data processing module (500) further includes: A fracturing curve analysis and early warning unit is provided, wherein the input terminal of the fracturing curve analysis and early warning unit is connected to the third output terminal of the data processing unit, and the first output terminal of the fracturing curve analysis and early warning unit is connected to the second input terminal of the display unit; the fracturing curve analysis and early warning unit is configured as follows: The data processing unit analyzes the data frame output by the data processing unit, and outputs a warning signal if the analysis result does not meet the preset requirements. The display unit then displays the warning information based on the warning signal.

Images