A drill bit condition monitoring device and method based on a fiber optic distributed sensor

Abstract

The application discloses a kind of based on optical fiber distributed sensor's drill bit state monitoring device and method, belong to oil drilling technical field.The application is by laying multiple groups of optical fiber sensor on drill bit, to collect and analyze the temperature distribution, strain distribution and vibration distribution data when drill bit works, according to strain distribution obtains the weight on bit distribution of drill bit, the state of drill bit is monitored in real time, and carry out drill bit working state prompt and realize alarm function.The strain measurement in monitoring process can but not limited to utilize the optical fiber strain sensing mechanism based on vernier effect, combine vernier sensitization effect with optical fiber interferometer light transmission characteristics, not only can more sensitively perceive the change of strain, improve the sensitivity of sensor, also can avoid the influence of ambient temperature on drilling pressure measurement result, realize the weight on bit distribution curve of drill bit of drilling equipment and the alarm function such as drilling pressure distribution abnormal due to cutting tooth wear.

Description

Technical Field

[0001] This invention belongs to the field of oil drilling technology and is used to monitor real-time data and provide early warning prompts for drill bits during operation. In particular, it relates to a drill bit status monitoring device and method based on fiber optic distributed sensors. Background Technology

[0002] Oil wells are drilled in stages, each with a different diameter; each stage is called a stage. The drilling rig transmits weight (WOB - drill bit weight), rotation (RPM - revolutions per minute), and torque via the drill string to facilitate drilling. Drill bits are divided into two main groups: roller cone bits (or taper bits, most commonly three-tapered bits) and stationary end mills. The main difference between these two groups is that roller cone bits cut rock through a crushing mechanism, while stationary end mills cut rock through a shearing mechanism. Oil drilling is a crucial step in oil and gas field development, and a significant factor affecting drilling efficiency is the use of drill bit equipment. In daily drilling operations, drill bit damage or failure is inevitable. Drill bit malfunctions severely impact drilling progress, reducing efficiency and quality. Therefore, ensuring the normal operating condition of drill bit equipment during drilling is extremely important. In daily construction operations, continuously monitoring the status of drilling equipment and taking reasonable and effective measures in a timely manner can prevent excessive damage to the drilling equipment and play a positive role in promoting the normal operation and use of the drilling bit.

[0003] An existing system for monitoring drill bit wear, patent number (CN112272728A), includes a drill bit with a cutting surface, an internal matrix, and a channel located in the internal region of the drill bit below the cutting surface; a source of pressurized drilling fluid, the internal matrix of the drill bit being connected to the source of pressurized drilling fluid and configured to receive drilling fluid from the internal matrix; and a monitor for monitoring the pressurized drilling fluid; wherein the channel is configured to release drilling fluid to the outside of the drill bit when the cutting surface above the internal region wears and exposes the channel; thus achieving a means of detecting its wear. In actual use, the downhole working environment during drilling is transient and complex. Existing drill bit condition monitoring devices are not perfect and cannot provide comprehensive monitoring of the drill bit, making it difficult to detect drill bit damage in a timely manner. Furthermore, the harsh drilling conditions place high demands on sensors, requiring high temperature resistance and vibration resistance. The deployment of sensors on downhole drill bits is sparse, and there are bottlenecks in acquiring near-drill bit signals, resulting in poor drill bit detection performance.

[0004] Therefore, there is a need in the prior art for a drill bit condition monitoring device and method based on fiber optic distributed sensors, which includes means for detecting wear and abnormal operating conditions at low cost by utilizing systems and components already present in the drill bit or drill string in conjunction with fiber optic sensors. As will be described in more detail below, the present invention aims to solve at least partially the problems of the prior art in a practical and effective manner. Summary of the Invention

[0005] The purpose of this invention is to provide a drill bit condition monitoring device and method based on fiber optic distributed sensors. The device uses fiber optic sensors, which have advantages such as strong anti-interference ability and no electrical transmission. In addition, compared with traditional sensors, fiber optic sensors have the characteristics of strong anti-interference, high sensitivity, fast response, convenient installation, easy distributed deployment, and reliable performance, thereby improving the monitoring effect of drill bits.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a drill bit status monitoring device based on optical fiber distributed sensors, including a drill string and a drill bit installed on the drill string. Multiple sets of optical fiber sensors are installed on the drill bit, wherein multiple optical fiber sensors are installed at the bottom of the cutting teeth of the drill bit's blades. The cutting blades of the drill bit are provided with wiring slots for laying optical fibers. After the optical fibers are connected to the optical fiber sensors, they are connected to the optical fiber slip ring inside the cavity of the drill bit through the wiring slots. The optical fibers and optical fiber sensors are encapsulated under high temperature and high pressure. A power supply compartment is installed inside the drill string, and a detection module is installed inside the power supply compartment. The optical fiber sensors and the detection module are connected through optical fibers.

[0007] In one possible implementation, the fiber optic sensor includes a fiber optic multi-parameter sensor, a fiber optic vibration sensor, and a fiber optic pressure sensor. The multi-parameter sensor is used to measure the temperature and strain at the bottom of multiple cutting teeth on the blade, the fiber optic vibration sensor is used to measure the vibration of the blade, and the fiber optic pressure sensor is used to measure the pressure in different flow channels.

[0008] In one possible implementation, the detection module includes an optical signal transmission module, a circulator, a time-division multiplexer and a wavelength-division multiplexer, an optical signal conditioning module, and a data processing module. The fiber optic multi-parameter sensor, the fiber optic vibration sensor, and the fiber optic pressure sensor are respectively connected to the optical signal transmission module via optical fibers.

[0009] In one possible implementation, the fiber optic multi-parameter sensor includes a reference arm and a sensing arm, and multiple fiber optic multi-parameter sensors are deployed, each used to measure the temperature and drilling pressure at the current location; fiber optic vibration sensors are deployed on each cutter wing, and one or more fiber optic vibration sensors are deployed on each cutter wing; fiber optic pressure sensors are deployed in the flow channel of the drill bit near the nozzle, and one or more fiber optic pressure sensors are deployed to measure the drilling fluid pressure and whether the drill bit cleaning is normal.

[0010] The drill bit has multiple holes for placing fiber optic sensors. These sensors are located at the bottom of the cutting teeth on the drill bit's blades and are fixed with high-temperature resistant adhesive. The drill bit blades have channels for laying optical fibers, serving as wiring grooves to guide the fibers. These wiring grooves consist of two parts: a cylindrical cavity connecting the sensor and the flow channel, and a recess in the flow channel wall. One end of the wiring groove connects to the drill bit cavity inside the nozzle, and the other end connects to the fiber optic sensor. The optical fiber is laid close to the inner side of the drill bit cavity, and a protective tube is fitted over the surface of the optical fiber inside the drill bit. The fiber optic cable is laid within the wiring groove. The fiber optic cable connects from the fiber optic sensor through the wiring groove to the fiber optic slip ring inside the drill bit cavity. Multiple fibers pass through the fiber optic slip ring to form a single multi-core fiber for transmission.

[0011] Fiber optic multi-parameter sensors are installed at the bottom of the drill bit's cutting teeth, with a 1mm thickness distance from the welding point of the cutting teeth. This facilitates proper welding of the cutting teeth during sensor installation and ensures the accuracy of the sensor's measurement signals. High-temperature resistant adhesive is used to fix the fiber optic multi-parameter sensors, which are tangentially placed at the bottom of the cutting teeth to measure the strain under vertical downward pressure. The cutting teeth to be equipped with sensors are selected evenly and arranged in an S-shape. Because uneven stress is prone to occur at the two ends of the cutter blade and at the L-shaped bends, an additional fiber optic multi-parameter sensor is installed at these points to facilitate more comprehensive monitoring of the drill bit's condition. A set of sensors is placed at the bottom of the remaining cutting teeth. Each fiber optic multi-parameter sensor includes a reference arm and a sensing arm. Through decoupling, the temperature and strain at the current cutting tooth position are obtained, thus revealing the temperature and drill pressure distribution of the drill bit. Each cutter blade uses a single optical fiber to connect to a group of fiber optic sensors, including multiple fiber optic multi-parameter sensors, fiber optic vibration sensors, and fiber optic pressure sensors. Each sensor group utilizes a wavelength division multiplexer to select different operating wavelengths and combines this with a time division multiplexer to analyze the data using the time-division characteristics of the sensor response time. The number of fiber optic slip ring channels is selected based on the number of cutter blades; for example, a 5-channel fiber optic slip ring is selected for 5 cutter blades. Simultaneously, the transmitted optical fibers need to be encased in protective tubing.

[0012] The drilling tool consists of multiple sections with adjacent threaded connections, and its optical fibers are connected through optical fiber terminals.

[0013] The drilling equipment status indicators and alarms use thresholds to determine if the equipment is functioning correctly; exceeding these thresholds triggers an alarm. Rapid changes in drill bit temperature, strain, and vibration per unit time also trigger status indicators. Fiber optic pressure sensors installed within the flow channels measure flow channel pressure; exceeding thresholds triggers an alarm. When temperature, drill pressure, and vibration exceed the drill bit's withstand thresholds, the system issues an over-limit alarm. The distribution curves of drill bit temperature, drill pressure, and vibration indicate uneven stress, temperature, and vibration, thus assessing drill bit wear. Significant differences in temperature, stress, and vibration signals between drill bit blades trigger an anomaly alarm, and the distribution curves simultaneously indicate the drill bit's operating status.

[0014] On the other hand, embodiments of the present invention also provide a drill bit condition monitoring method based on fiber optic distributed sensors, the method comprising the following steps:

[0015] Step 1: Deploy fiber optic sensors: Deploy fiber optic multi-parameter sensors at multiple cutting teeth on each blade of the drill bit. The fiber optic multi-parameter sensors are used to collect the temperature and strain at the current cutting tooth position. Deploy fiber optic vibration sensors on the blades of the drill bit. The fiber optic vibration sensors are used to collect the vibration of each blade. Deploy fiber optic pressure sensors in the flow channel of the drill bit. The fiber optic pressure sensors are used to collect the pressure in the flow channel.

[0016] Step 2, Data Acquisition: The fiber optic multi-parameter sensor, fiber optic vibration sensor, and fiber optic pressure sensor are used to acquire the temperature and strain distribution signals at different cutting teeth, the vibration signal of each blade, and the flow channel pressure signal, respectively.

[0017] Step 3: Data Processing: Based on the temperature and strain distribution signals, vibration signals, and flow channel pressure signals, determine the temperature distribution changes of each blade, the drilling pressure at each cutting tooth position, and the vibration distribution of each blade when cutting the formation, and plot the corresponding state distribution curves.

[0018] Step 4, Analysis: Analyze the status distribution curves in Step 3 to provide status prompts for the drill bit equipment and alarms for over-limit temperature, over-limit vibration, abnormal temperature distribution due to cutting tooth wear, and abnormal drilling pressure distribution.

[0019] In one possible implementation, the fiber optic multi-parameter sensor includes a reference arm and a sensing arm. Multiple fiber optic multi-parameter sensors are distributed across each cutter wing. The reference arm of each fiber optic multi-parameter sensor remains relaxed, while the sensing arm is pre-tensioned. The signals collected by the fiber optic multi-parameter sensors are decoupled to obtain the temperature and strain distribution signals at the current cutting tooth position. Of course, the fiber optic multi-parameter sensor can be replaced by separate fiber optic temperature sensors and fiber optic strain sensors, which does not affect the implementation of this patent.

[0020] In one possible implementation, step two includes: Step a, fiber optic multi-parameter sensor data acquisition: The temperature of the drill bit is measured through the reference arm to obtain temperature signals at various locations. After processing the temperature signals, the temperature distribution of the entire drill bit is obtained. The temperature and strain at the current position on the drill bit are measured through the sensor arm. The measured signals are decoupled to obtain strain signals. After processing the strain signals, the drilling pressure at the current position is obtained, thereby obtaining the drilling pressure distribution of the entire drill bit and analyzing the wear and stress of the drill bit; Step b, fiber optic vibration sensor data acquisition: The vibration on each cutter blade is measured through the fiber optic vibration sensor. After processing the obtained vibration signals, the vibration distribution of the entire drill bit is obtained; Step c: The data acquired in steps a and b above are used to plot the state distribution curve of the entire device.

[0021] In one possible implementation, during data processing, the fiber optic multi-parameter sensor, based on the vernier effect of fiber optic strain sensing, combines the vernier sensitization effect with the light transmission characteristics of a fiber optic interferometer. By cascading two interferometers on the same fiber using the same physical structure, and adjusting the multi-core fiber length, core spacing, and diameter structural parameters of the cascaded interferometers, strain measurement with environmental temperature stability is achieved. One of the cascaded interferometers serves as the reference arm of the fiber optic multi-parameter sensor, and the other as the interferometer arm.

[0022] In one possible implementation, step three includes: step a: when the FSRs of the output spectra of the two interferometers are similar but not identical, a periodic envelope signal is generated after superposition; step b: when the ambient temperature changes, the spectra on the two interferometers change in the same direction, thus generating a smaller temperature sensitivity; because the sensing arm is affected by strain changes while the reference arm is not affected by strain changes.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] This invention embeds fiber optic sensors at the bottom of multiple cutting teeth of the cutter blade for distributed temperature, drilling pressure, and vibration measurements. Since drill bit wear is unavoidable during drilling, the sensor reacts more violently when the drill bit malfunctions, and the abnormal temperature, drilling pressure, and vibration signals are more obvious. This facilitates the analysis of drill bit status distribution curves and enables faster and more intuitive monitoring of the drill bit's working status.

[0025] This invention measures the drilling pressure applied to the cutting teeth during drilling through a detection module, which facilitates system control and data analysis during the drilling process. It enables continuous evaluation of drilled formations and can also monitor the spatial distribution of drilling pressure through this distributed sensing technology. In the long term, by measuring the force distributed on the cutting teeth, it may also be possible to monitor the wear evolution of individual cutting teeth, which is something that existing drill bit sensors cannot detect. This can help optimize drill bit design.

[0026] This invention utilizes distributed measurements via fiber optic multi-parameter sensors deployed at the bottom of the cutting teeth on the drill bit. Each fiber optic multi-parameter sensor includes a sensing arm and a reference arm, with the reference arm kept in a relaxed state and the sensing arm designed with pre-tension. Through decoupling, the temperature and strain at the current cutting tooth position are obtained, thus determining the overall drill bit pressure distribution. A drill pressure status curve for the entire equipment is plotted, providing drill bit pressure status alerts and alarms for abnormal drill pressure distribution. Furthermore, the invention obtains the overall temperature distribution of the drill bit, plotting a temperature status curve for the entire equipment based on the temperature distribution, and providing drill bit temperature status alerts and alarms for abnormal temperatures. Finally, fiber optic vibration sensors obtain the vibration distribution of each blade on the entire drill bit, plotting a vibration status curve for the entire equipment based on the vibration distribution, and providing drilling equipment vibration status alerts and alarms for abnormal vibrations.

[0027] This invention utilizes an optical fiber pressure sensor deployed within the flow channel to obtain the channel pressure, thereby determining whether the drilling fluid can be normally supplied to the formation for drilling operations. It employs an optical fiber multi-parameter sensor based on the vernier effect, combining the vernier sensitization effect with the light transmission characteristics of an optical fiber interferometer. This not only allows for more sensitive detection of strain changes and improves sensor sensitivity but also avoids the influence of ambient temperature on strain measurement results. Based on the analysis of drill bit temperature, drilling pressure, and vibration distribution, the invention monitors the drill bit status in real time, providing drill bit operating status alerts and alarm functions. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A cross-sectional view showing the sensor placement location according to the present invention;

[0030] Figure 2 This is the sensor layout structure at the bottom of the cutting tooth according to the present invention;

[0031] Figure 3 This is a schematic diagram of the layout of a single blade fiber optic sensor according to the present invention;

[0032] Figure 4 This is a schematic diagram of the connection structure between adjacent drilling tools according to the present invention;

[0033] Figure 5 This is a flowchart of the present invention;

[0034] Figure 6 This is a schematic diagram of the vernier effect output spectrum of the present invention;

[0035] Figure 7 The figure shows the simulation results of the vernier effect of the present invention.

[0036] Reference numerals: 03. Drill bit; 011. Cutting teeth; 012. Fiber optic cable in drill bit section; 013. Fiber optic vibration sensor; 014. Fiber optic multi-parameter sensor; 015. Fiber optic slip ring; 017. Fiber optic pressure sensor; 0141. Reference arm; 0142. Sensing arm; 0161. Cylindrical groove; 0162. Flow channel side groove; 021. Optical signal transmission module; 022. Optical signal demodulation module; 023. Circulator; 024. Data processing module; 0211 0212. Light source; 0221. Time division multiplexer I and wavelength division multiplexer I; 0222. Time division multiplexer II and wavelength division multiplexer II; 0222. Temperature demodulation photodetector and signal conditioning circuit; 0223. Strain demodulation photodetector and signal conditioning circuit; 0224. Vibration demodulation photodetector and signal conditioning circuit; 0225. Pressure demodulation photodetector and signal conditioning circuit; 031. Connector; 032. Connecting section; 033. Fiber optic connector terminal; 034. Fiber optic cable. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] like Figures 1-4 As shown, this invention provides a drill bit status monitoring device based on fiber optic distributed sensors. The device includes a drilling platform, a drill string 03, and a drill bit mounted on the drill string 03. Multiple fiber optic multi-parameter sensors 014 are mounted on the drill bit, positioned at the bottom of the cutting teeth on the drill bit's blades. These sensors are tangentially embedded at the bottom of the cutting teeth and fixed with high-temperature resistant adhesive. An optical fiber channel is provided inside the drill bit, serving as a wiring groove for guiding the optical fiber. This channel includes a cylindrical groove 0161 and a flow channel side groove 0162. A protective tube is fitted over the surface of the optical fiber inside the drill bit. The protective tube and sensors are coated with a high-temperature resistant coating, capable of withstanding 300°C, allowing for longer downhole operation.

[0039] The drill string 03 contains a power supply compartment, which houses a detection module. Fiber optic multi-parameter sensors 014, fiber optic vibration sensors 013, and fiber optic pressure sensors are connected to the detection module via fiber optic slip rings. The detection module is connected to the drilling platform. This technology employs distributed fiber optic measurement. Multiple fiber optic multi-parameter sensors 014, including reference arms and sensing arms, are deployed on each cutter blade of the drill bit. Through decoupling, the temperature and strain at the current cutting tooth position are obtained, thus determining the overall drill bit pressure distribution and providing drill bit pressure status alerts and alarms for abnormal pressure. The temperature distribution of the entire drill bit is also obtained, and a temperature distribution curve for the entire equipment is plotted, providing drill bit temperature status alerts and alarms for abnormal temperatures. Finally, the vibration distribution of the entire drill bit is obtained using fiber optic vibration sensors 013, and a vibration status curve for the entire equipment is plotted, providing drilling equipment vibration status alerts and alarms for abnormal vibrations. Each cutter blade uses a single optical fiber to connect to each group of sensors. Each group of sensors uses a time-division multiplexer and a wavelength-division multiplexer (WDM) to select different operating wavelengths and analyzes the data using the time-division characteristics of the sensor response time. The number of fiber optic slip ring channels is selected according to the number of drill blades; for example, a 5-channel fiber optic slip ring is selected for 5 cutter blades.

[0040] In this embodiment, fiber optic multi-parameter sensors are evenly distributed on half the number of cutting teeth 011 on each blade. Cutting teeth 011 are selected in an S-shape, and an additional fiber optic multi-parameter sensor is distributed at both ends and the bends of the L-shape. A fiber optic multi-parameter sensor is placed at the bottom of each cutting tooth 011, tangentially positioned at the bottom of the cutting tooth 011. The fiber optic multi-parameter sensor includes a reference arm 0141 and a sensing arm 0142. The reference arm 0141 is kept in a relaxed state, and the sensing arm 0142 is designed to be pre-tensioned and fixed. The temperature and strain at the current cutting tooth position are obtained through decoupling.

[0041] In this embodiment, the drilling platform is a land drilling platform. This technology is an improvement on existing drilling platform technology. It incorporates a power supply compartment and a detection module inside the drill bit, connected to the drilling platform's processing system. The detection module is a data processing module 024. The power supply compartment houses a battery connected to the detection module, which is also connected to the drilling platform's processing system. Multiple fiber optic multi-parameter sensors are installed on the drill bit and connected to the detection module via fiber optic slip rings 015. Data monitored by the fiber optic multi-parameter sensors 014 is transmitted to the data processing module 024 for processing and then transmitted to... The drilling platform displays the following: the fiber optic multi-parameter sensor 014 includes, but is not limited to, fiber optic temperature sensor, fiber optic strain sensor, fiber optic vibration sensor, and fiber optic pressure sensor. The fiber optic multi-parameter sensor includes a reference arm and a sensing arm. The fiber optic slip ring 015 is a rotary fiber optic conductive slip ring provided by JARCH Electromechanical. The drill bit model is PDC133, the internal unit model of the power supply compartment is GM8035, the circulator model is DP0595c, the time division multiplexer model is ZD-A3, and the wavelength division multiplexer model is 2902660.

[0042] In specific implementation, the monitoring device of the present invention includes an optical fiber multi-parameter sensor 014 disposed at the bottom of the three-wing cutting teeth of the drill bit. The optical fiber multi-parameter sensor 014 adopts optical fiber distributed measurement, that is, the sensing arm and the reference arm are tangentially placed at the bottom of the cutting teeth of the drill bit. Multiple such sensors are disposed on each cutting wing. At the connection between the drill tool 03 and the drill bit, an optical fiber slip ring 015 is disposed to connect the drill tool 03 and the optical fiber at the drill bit. The optical fiber is embedded in the optical fiber channel disposed inside the drill bit to the bottom of the cutting teeth. The optical fiber 012 of the drill bit is connected to the optical fiber multi-parameter sensor 014 through the channel. The channel guides the optical fiber 012 of the drill bit for transmitting signals. The wiring groove includes a cylindrical groove 0161 connecting the sensor and the flow channel and a groove 0162 on the side of the flow channel.

[0043] In this embodiment, the monitoring device employs distributed fiber optic measurement. Multiple fiber optic multi-parameter sensors, including a reference arm and a sensing arm, are deployed at the bottom of the cutting teeth of the drill bit. A fiber optic slip ring 015 at the connection between the drill string 03 and the drill bit ensures relative stability between the sensor and the drill bit. The signal transmitted by the fiber optic multi-parameter sensor 014 is transmitted through the fiber optic cable 012 within the wiring groove on the drill bit, through the drill bit cavity, and then through the fiber optic slip ring 015 to the fiber optic cable on the drill string. After passing through the fiber optic slip ring 015, multiple fibers are encapsulated into a single multi-core fiber using a sleeve, and a protective sleeve is provided for the fiber. This significantly simplifies the system structure while ensuring relative stability between the sensor and the drill bit, preventing damage to the fiber optic cable during rotation.

[0044] See Figures 3 to 4As shown, the drill string is arranged in multiple sections, with adjacent sections threaded together. Optical fibers between sections are connected via optical fiber terminals. The multi-section drill string includes a drill string 03 that can be combined and connected to the drill bit and the power supply compartment. The drill string 03 has a connector 031 at its front end and a connecting section 032 at its rear end. Optical fiber connection terminals 033 are located at the center of the connector 031 and the connecting section 032. An optical fiber 034 is laid behind the connector 031 and on the inner wall of the drill string 03. One end of the optical fiber 034 is connected to the optical fiber connection terminal 033 at the center of the connector 031, and the other end is connected to the optical fiber connection terminal 033 at the center of the connecting section 032. This is used to transmit data monitored by the optical fiber multi-parameter sensor to a host computer for display. The power supply compartment is located within the drill string, and the optical fiber connection between the drill string and the drill bit is achieved using an optical fiber slip ring 015. The optical fiber laid on the inner wall of the drill string 03 is armored and can withstand temperatures exceeding 300°C.

[0045] See Figure 5 The power supply compartment integrates a detection module, which includes an optical signal transmission module 021, an optical signal demodulation module 022, a circulator 023, and a data processing module 024. The optical signal transmission module 021 includes a light source 0211. The light source 0211 transmits the optical signal through the circulator 023 and time-division multiplexer 1 and wavelength-division multiplexer 1 0212 to distributed fiber optic sensors deployed on each blade wing, including multiple fiber optic multi-parameter sensors 014, fiber optic vibration sensors 013, and fiber optic pressure sensors 017. The optical signal is then returned to the circulator 023 through time-division multiplexer 1 and wavelength-division multiplexer 1 0212, and subsequently transmitted to the demodulation module through time-division multiplexer 2 and wavelength-division multiplexer 2 0221 for demodulation. The signal then passes through corresponding temperature demodulation photodetectors and signal modulators. The demodulated temperature, strain, vibration, and pressure signals obtained by the demodulation circuits 0222, 0223, 0224, 0225, 0222, 0223, 0224, and 0225 are sent to the data processing module 024 for real-time analysis and processing to control the working state of the drill bit. Alternatively, the data processing module 024 can upload the data to the drilling platform via measurement-while-drilling (MWD) tools, allowing drilling engineers to analyze the data and control the working state of the drill bit. Alternatively, optical fiber can be used to deploy the optical signal transmission module 021, optical signal demodulation module 022, circulator 023, and data processing module 024 on the wellhead. For example, if excessive drilling pressure is detected, certain parameters of the surface tools can be adjusted to reduce the drilling pressure. The power supply compartment is treated with shockproof, heat-insulating, and anti-fouling measures to ensure the normal operation of the photoelectric devices inside. The power supply compartment, connecting section 032, and connecting head 031 are threadedly connected to the drill bit.

[0046] In practical implementation: the drill bit and drill string 03 are connected via fiber optic slip ring 015. The quantity and type of drill string 03 are assembled and installed according to actual needs, and then the drill string assembly is sent downhole. During operation, the light emitted by the light source 0211 inside the power supply compartment passes through circulator 023 and time-division multiplexer 1 and wavelength-division multiplexer 1 0212, respectively, and enters the fiber optic sensors distributed on the drill bit. The decoupling obtains the changes in strain, temperature, vibration, and pressure at each measured point. The optical signals returned by time-division multiplexer 1 and wavelength-division multiplexer 1 0212 then pass through circulator 023 and enter time-division multiplexer 2 and wavelength-division multiplexer 2 0221 in the optical signal demodulation module 022. They then pass through the corresponding temperature demodulation photodetector and signal conditioning circuit 0222, strain demodulation photodetector and signal conditioning circuit 0222, respectively. 223. The vibration demodulation photoelectric detector and signal conditioning circuit 0224 and the pressure demodulation photoelectric detector and signal conditioning circuit 0225 demodulate the measured physical quantities of temperature, strain, vibration and pressure, which are then sent to the data processing module 024. After analysis and processing by the data processing module 024, the working state of the drill bit is controlled or uploaded to the drilling platform through the measurement while drilling (MWD) tool. The drilling engineer analyzes the data to obtain distributed temperature, distributed drilling pressure, vibration and flow channel pressure, and controls the working state of the drill bit in real time. This optimizes the use of drilling tools. Alternatively, a measurement and information channel can be formed through the fiber optic cable 034, allowing all measurement information of the downhole drilling tool assembly to be shared. All components of the downhole drilling tool assembly can use the measurement information to adjust their working state, thereby achieving the purpose of optimizing drilling.

[0047] like Figures 5-7 As shown, the present invention also provides a drill bit condition monitoring method based on fiber optic distributed sensors, the method comprising the following steps:

[0048] Step 1: Install fiber optic multi-parameter sensors at multiple cutting teeth on each blade of the drill bit to obtain the temperature and strain at the current cutting tooth position; install fiber optic vibration sensors on each blade of the drill bit near the L-shaped bend to obtain the vibration of each blade; and install fiber optic pressure sensors in each flow channel of the drill bit to obtain the pressure in the flow channel.

[0049] Step 2: Data Acquisition: Use fiber optic multi-parameter sensors to obtain the temperature and drilling pressure at different cutting teeth, use fiber optic vibration sensors to obtain the blade vibration signal, and use fiber optic pressure sensors to obtain the pressure in each flow channel.

[0050] Data acquisition includes collecting data from multiple fiber optic multi-parameter sensors deployed at the bottom of the drill bit's cutting teeth, fiber optic vibration sensors deployed inside the cutter wings, and fiber optic pressure sensors located at the nozzles on the inner wall of the flow channel.

[0051] Step a: Data acquisition from multiple fiber optic multi-parameter sensors; temperature measurement of the drill bit by the reference arm; and processing of the data to obtain the temperature distribution of the entire drill bit.

[0052] Step b: Data acquisition by fiber optic pressure sensor. The sensor arm measures the temperature and strain on the drill bit. After decoupling and processing the strain signal, the drill pressure distribution on each cutting tooth can be obtained.

[0053] Step c: Fiber optic vibration sensor data acquisition. The vibration of the drill bit is measured by fiber optic vibration sensors deployed on the cutter wings. After data processing, the vibration distribution of the entire drill bit can be obtained.

[0054] Step d: Plot the entire device status curve using the data collected in steps a, b, and c above.

[0055] Step 3: Data Processing: Obtain the drilling pressure distribution of the entire drill bit, the temperature distribution of each cutter blade when cutting the formation, and the vibration distribution of each cutter blade when cutting the formation, and plot the corresponding state distribution curves;

[0056] Step a: When the FSR of the output spectra of the two interferometers (reference arm and sensor arm) are similar but not the same, they will generate a periodic envelope signal after superposition.

[0057] Step b: When the ambient temperature changes, the spectra on both interferometers will change in the same direction, resulting in a smaller temperature sensitivity; at the same time, the reference interferometer is not affected by the strain change, so it can realize strain sensing and play a role in enhancing sensitivity.

[0058] Step 4: Analysis: Analyze the distribution curves from Step 3 to provide drill bit status indication and alarms; utilize a fiber optic multi-parameter sensor based on the vernier effect, combining the vernier sensitization effect with the light transmission characteristics of the fiber optic interferometer, which not only more sensitively senses strain changes and improves sensor sensitivity, but also avoids the influence of ambient temperature on measurement results. Specifically, the deployment of the fiber optic multi-parameter sensor includes the deployment of a reference arm and a sensing arm, which are placed tangentially. The data processing of the fiber optic multi-parameter sensor is based on the vernier effect, a fiber optic strain sensing mechanism. It combines the vernier sensitization effect with the light transmission characteristics of an SMS interferometer. By cascading two interferometers on the same fiber using the same physical structure, and adjusting the length, spacing, and diameter of the multi-core fiber of the cascaded SMS interferometers, a high-sensitivity strain sensor with environmental temperature stability is achieved. The structure of the fiber optic multi-parameter sensor can, but is not limited to, deploying reference arms and sensing arms at various distribution points and utilizing the vernier sensitization effect for sensitivity enhancement. Combining the optical vernier effect with fiber optic sensing technology, the vernier effect being an effective method for improving sensor measurement sensitivity, and using two cascaded interferometers, a fiber optic multi-parameter sensor structure with environmental temperature stability and high sensitivity can be realized.

[0059] Assume that the temperature and strain sensitivities of sensor interferometer one are respectively and The temperature and strain sensitivities of reference interferometer II are respectively And 0. At this point, the strain sensitivity of the sensor can be expressed as:

[0060]

[0061] Since both the first sensing interferometer and the second reference interferometer are affected by temperature, the analysis of temperature sensitivity is slightly more complex. The temperature sensitivity is divided into two parts: the contributions of the first sensing interferometer and the second reference interferometer to the temperature sensitivity. The amplification factors of the first sensing interferometer and the second reference interferometer are expressed as follows:

[0062]

[0063] Since the two interferometers have opposite effects on the offset direction of the envelope, the total temperature sensitivity of the sensor can be expressed as:

[0064]

[0065] From the above formula, it can be seen that when the interferometer structures are the same, the interferometer's When the temperature sensitivity is close to 0, the temperature sensitivity of the constructed strain sensor approaches 0.

[0066] Two interferometers with different periodic spectra are cascaded together. When incident light from a light source passes through this structure, it produces a periodically changing envelope (as follows). Figure 6 As shown); assuming the sensor interferometer has a spectrum FSR 1 is 1.1 nm, reference interferometer spectrum FSR 2 is 1.0 nm. The FSR spectra of the two interferometers are similar but not equal. Figure 6 (c) is the spectrum after the two are superimposed; when the spectrum of sensor interferometer one shifts to the right by 0.1 nm under strain, the superimposed spectral envelope will have a wavelength shift of 1 nm, which is equivalent to 10 times the spectral shift of sensor interferometer one. Figure 7 Therefore, higher sensitivity can be obtained. Fiber optic multi-parameter sensors utilize the vernier sensitization effect to obtain temperature and strain signals at the drill bit's position. Accurate measurement of the strain experienced by the drill bit is a key technical issue in achieving accurate drill pressure measurement in existing equipment. Achieving accurate measurement through the designed fiber optic multi-parameter sensor has significant engineering implications for drilling. Based on the analysis of the drill bit's temperature, drill pressure, and vibration distribution, the sensor can monitor the drill bit's condition, provide drill bit operating status alerts, and implement alarm functions.

[0067] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A drill bit condition monitoring device based on fiber optic distributed sensors, comprising a drill string and a drill bit mounted on the drill string, characterized in that: The drill bit is equipped with multiple sets of fiber optic sensors, which are located at the bottom of the cutting teeth on the cutter wings, on the cutter wing body, and near the nozzle in the flow channel. The fiber optic sensors at the bottom of the cutting teeth are multi-parameter fiber optic sensors, used to perform distributed temperature and strain measurements on the bottom of multiple cutting teeth, and to obtain the drilling pressure at each cutting tooth position based on the strain. The fiber optic sensors on the cutter wing body are vibration sensors, used to measure the vibration of each cutter wing. The fiber optic sensors near the nozzle in the flow channel are pressure sensors, used to measure drilling fluid pressure and determine whether the drill bit cleaning is normal. The cutter wings of the drill bit have wiring slots for laying fiber optic cables. The fiber optic cables are connected to the fiber optic sensors and then to fiber optic slip rings inside the drill bit's cavity through the wiring slots. The fiber optic cables and sensors are encapsulated under high temperature and high pressure. A power supply compartment is located inside the drill string, and a detection module is located within the power supply compartment. The fiber optic sensors are connected to the detection module via the fiber optic cables. The multi-parameter fiber optic sensor includes a reference arm and a sensing arm, used to achieve decoupled measurement of temperature and strain. During data processing, the fiber optic multi-parameter sensor, based on the vernier effect fiber optic strain sensing mechanism, combines the vernier sensitization effect with the light transmission characteristics of the fiber optic SMS interferometer. By cascading two SMS interferometers on the same fiber and using the same physical structure, the cascaded SMS interferometers achieve strain measurement with stable ambient temperature by adjusting the multi-core fiber length, core spacing, and diameter structural parameters. One of the cascaded SMS interferometers serves as the reference arm of the fiber optic multi-parameter sensor, and the other serves as the interferometer arm of the multi-parameter sensor.

2. The drill bit condition monitoring device based on fiber optic distributed sensors according to claim 1, characterized in that: The detection module includes an optical signal transmission module, a circulator, a time-division multiplexer, a wavelength-division multiplexer, an optical signal conditioning module, and a data processing module. The fiber optic multi-parameter sensor, the fiber optic vibration sensor, and the fiber optic pressure sensor are respectively connected to the optical signal transmission module via optical fibers.

3. A monitoring method applied to the drill bit condition monitoring device based on fiber optic distributed sensors as described in any one of claims 1-2, characterized in that: The method includes the following steps: Step 1: Deploy fiber optic sensors: Deploy fiber optic multi-parameter sensors at multiple cutting teeth on each blade of the drill bit. The fiber optic multi-parameter sensors are used to collect the temperature and strain at the current cutting tooth position. Deploy fiber optic vibration sensors on the blades of the drill bit. The fiber optic vibration sensors are used to collect the vibration of each blade. Deploy fiber optic pressure sensors in the flow channel of the drill bit. The fiber optic pressure sensors are used to collect the pressure in the flow channel. Step 2, Data Acquisition: The fiber optic multi-parameter sensor, fiber optic vibration sensor, and fiber optic pressure sensor are used to acquire the temperature and strain distribution signals at different cutting teeth, the vibration signal of each blade, and the flow channel pressure signal, respectively. Step 3: Data Processing: Based on the temperature and strain distribution signals, vibration signals, and flow channel pressure signals, determine the temperature distribution changes of each blade, the drilling pressure at each cutting tooth position, and the vibration distribution of each blade when cutting the formation, and plot the corresponding state distribution curves. Step 4, Analysis: Analyze the status distribution curves in Step 3 to provide status prompts for the drill bit equipment and alarms for excessive temperature, excessive vibration, abnormal temperature distribution caused by cutting tooth wear, and abnormal drilling pressure distribution.

4. The drill bit condition monitoring method based on fiber optic distributed sensors according to claim 3, characterized in that: The fiber optic multi-parameter sensor includes a reference arm and a sensing arm. Multiple fiber optic sensors are arranged on each blade. The reference arm is kept in a relaxed state, and the sensing arm is subjected to a pre-tension. The signals collected by the fiber optic multi-parameter sensor are decoupled to obtain the temperature and strain signals at the current cutting tooth position.

5. The drill bit condition monitoring method based on fiber optic distributed sensors according to claim 4, characterized in that: Step Two include: Step a) Fiber optic multi-parameter sensor data acquisition: The temperature of the drill bit is measured through the reference arm to obtain temperature signals at various locations. After processing the temperature signals, the temperature distribution of the entire drill bit is obtained. The temperature and strain at the current location on the drill bit are measured through the sensor arm. The measured signals are decoupled to obtain strain signals. After processing the strain signals, the drilling pressure at the current location is obtained, thereby obtaining the drilling pressure distribution of the entire drill bit and analyzing the wear and stress conditions of the drill bit. Step b, Fiber optic vibration sensor data acquisition: The vibration on each blade is measured by fiber optic vibration sensor, and the vibration signal is processed to obtain the vibration distribution of the entire drill bit. Step c: Plot the state distribution curve of the entire device using the data collected in steps a and b above.

6. The drill bit condition monitoring method based on fiber optic distributed sensors according to claim 1, characterized in that: Step three includes: Step a: When the FSRs of the output spectra of two SMS interferometers are similar but not the same, they are superimposed to generate a periodic envelope signal; Step b: When the ambient temperature changes, the spectra on the two SMS interferometers change in the same direction, resulting in a smaller temperature sensitivity; since the sensing arm is affected by the strain change while the reference arm is not affected by the strain change, strain sensing is achieved through decoupling, which also plays a role in enhancing sensitivity.

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