Drilling directional nipple based on combination of gyroscope and accelerometer

Abstract

The invention discloses a drilling directional short section based on combination of a gyroscope and an accelerometer, which comprises a short section shell, one end of the short section shell is sealed, and the other opposite end of the short section shell is a mounting reference surface and is also provided with a wiring terminal; an inner table body is arranged in the short section shell and is provided with a gyroscope, an accelerometer, a signal processing unit and a power supply module for supplying power to the gyroscope, the accelerometer and the signal processing unit; wherein the gyroscope and the accelerometer are arranged in three directions, and attitude, angular velocity and linear velocity signals acquired by the gyroscope and the accelerometer are respectively sent to the signal processing unit for real-time resolving; the signal processing unit is connected with the upper computer through the wiring terminal and the communication line; and the signal processing unit sends the hole drift angle, the tool face angle and the azimuth angle obtained after calculation to an upper computer. The method is not affected by a magnetic field, dynamic continuous tracking measurement of the hole drift angle, the tool face angle and the azimuth angle is achieved through the measurement-while-drilling system, dynamic tracking is achieved, high precision of azimuth measurement is guaranteed, and accurate guiding information is provided for drilling operation.

Description

Technical Field

[0001] This invention belongs to the field of drilling measurement tool technology, and relates to a drilling orientation sub based on the combined use of a gyroscope and an accelerometer. Background Technology

[0002] In the exploration and development of oil, gas, and mineral resources, drilling is a crucial step. Drilling operations demand extremely high accuracy in wellbore trajectory measurement, which is key to ensuring efficient and safe drilling operations. As drilling environments become increasingly complex, directional drilling requires precise control of the drill bit's path according to the design to avoid underground obstacles, improve resource extraction efficiency, and reduce costs. For example, in cluster well operations, multiple wells are drilled from the same platform; if the wellbore trajectory deviates too much, it may lead to interference between wells and even safety accidents. Similarly, in the construction of complex well types such as horizontal wells and extended reach wells, accurately determining parameters such as the wellbore's azimuth and dip angle is a prerequisite for ensuring the drill bit accurately reaches the target reservoir. Traditional wellbore trajectory measurement methods have many limitations. Early magnetic surveying tools, such as magnetic compasses, are susceptible to interference from underground magnetic fields and steel components of drilling equipment, leading to significant measurement errors. In areas with complex geological conditions, such as near magnetite layers or high-voltage cables, magnetic surveying tools may even fail completely. Furthermore, some gravity-based surveying tools experience a significant decrease in accuracy in well sections with large inclination angles, failing to meet the demands of complex drilling operations. To address the limitations of traditional measuring tools in the drilling field, gyroscope tools have gradually come into focus, emerging and continuously developing in the field due to their unique technological advantages. Early mechanical gyroscopes, while meeting basic drilling measurement needs to some extent, suffered from problems such as large size, high power consumption, and significant drift errors. With technological advancements, optical gyroscopes (such as laser gyroscopes and fiber optic gyroscopes) have emerged. Optical gyroscopes offer advantages such as no mechanical wear, low drift rate, and fast response speed, greatly improving the accuracy and stability of wellbore trajectory measurement. For example, fiber optic gyroscopes can achieve real-time, continuous measurement of wellbore azimuth and dip angles with an accuracy of up to 0.1°, providing precise guidance information for directional drilling. However, fiber optic gyroscopes are expensive and bulky, making them unsuitable for use in confined spaces. In recent years, MEMS gyroscopes have also begun to be used in the drilling field. MEMS gyroscopes are characterized by their small size, low cost, and ease of integration, making them suitable for shallow wells or conventional well operations with relatively low requirements for measurement accuracy, thus reducing the cost of drilling measurements. With increasing drilling depths, more complex well configurations, and higher requirements for exploration and development accuracy, higher demands are being placed on the performance of gyroscope tools. In the high-temperature, high-pressure, and high-vibration downhole environment, gyroscope tools need to possess greater stability and reliability. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a drilling orientation sub based on the combined use of a gyroscope and an accelerometer, which can overcome the interference of strong magnetic fields, ensure high accuracy of orientation measurement, and provide accurate guidance information for drilling operations.

[0004] This invention is achieved through the following technical solution: A drilling directional sub based on the combination of a gyroscope and an accelerometer includes a sub housing, one end of which is sealed, and the other end is a mounting reference surface. This end is also provided with a wiring terminal. The short section housing contains an inner platform, on which a gyroscope, accelerometer, and signal processing unit are mounted, along with a power supply module that powers them. The gyroscope and accelerometer are both arranged in three directions: x A gyroscope and an accelerometer are installed along the axial direction; y A gyroscope and an accelerometer are installed along the axial direction; z A gyroscope and an accelerometer are installed along the axis; the attitude, angular velocity, and linear velocity signals collected by them are sent to the signal processing unit for real-time calculation. The signal processing unit is connected to the host computer via a terminal block and a communication line; the signal processing unit sends the calculated well inclination angle, tool face angle and azimuth angle to the host computer.

[0005] Furthermore, the inner platform is connected to the short section outer shell by a fastener, and a shock-absorbing ring is also provided between the inner platform and the short section outer shell; The gyroscope and accelerometer are connected to the signal processing unit via SPI interface, and the signal processing unit is connected to the host computer via RS422 interface.

[0006] Furthermore, the gyroscope sensor collects the rotation angle and angular velocity of the short section and sends them to the signal processing unit; The accelerometer collects the acceleration of the short section and sends it to the signal processing unit; The signal processing unit includes a CPU microprocessor with a built-in solution unit, a filtering unit, and a calibration and optimization unit.

[0007] Furthermore, the signal processing unit filters the acquired raw data and then performs calibration; Calculate attitude angles: The signal processing unit first calculates the pitch and roll angles of the short section, which reflect the attitude of the short section. Then, it calculates the azimuth angle to determine the pointing direction of the short section. Calculate the tool face angle based on the known attitude angle and azimuth angle; The calculated azimuth and tool face angles are output to the host computer as results.

[0008] Furthermore, the filtering unit is a first-order Kalman filter or an extended Kalman filter; The calibration optimization is based on the comparison of measurement results from prior instruments to obtain correction coefficients; and introduces temperature drift terms, installation angle terms, and magnetic field interference compensation terms.

[0009] Furthermore, the signal processing unit's calculations include a fast alignment mode and a precise alignment mode; The fast alignment mode relies solely on the angular velocity data from the gyroscope, and calculates the azimuth angle through integration. Precise cross-correction of criterion mode fusion gyroscope and accelerometer: Accelerometers can measure the gravity vector. If the attitude angle obtained by integrating the gyroscope is inconsistent with the direction of gravity sensed by the accelerometer, the accelerometer data is used as a reference to correct the gyroscope integration result.

[0010] Furthermore, the filtering algorithm for the fast alignment mode adopts a first-order Kalman filter algorithm; The filtering algorithm for the criterion mode is an adaptive extended Kalman filter algorithm; and the filter gain is adaptively adjusted: the residual of the gyroscope output data is analyzed in real time, which is the difference between the predicted value and the actual acquired value; if the residual increases, the filter gain is increased to quickly track the true value; if the residual decreases, the gain is decreased to smooth the output. Error states are also introduced: temperature drift term and installation angle term are added after filtering, and azimuth angle is estimated simultaneously to offset error sources; Furthermore, the precise criterion model undergoes 3-5 iterations within 0 seconds, with each iteration optimizing based on the error results of the previous iteration: In the first round, from 0 to 30 seconds, basic data is collected, and the azimuth angle is initially estimated using an extended Kalman filter. At the same time, the time periods with larger residuals are recorded. In the second round, from 30 to 60 seconds, local data resampling was added for the time period with large residuals, and the time synchronization deviation between the accelerometer and the gyroscope was corrected. In the third round, from 60 to 90 seconds, the error data from the first two rounds is used to optimize the magnetic field interference compensation term, and the final output is the azimuth angle after the error convergence.

[0011] Compared with the prior art, the present invention has the following beneficial technical effects: The drilling orientation sub based on the combined use of a gyroscope and an accelerometer provided by this invention, by incorporating a high-precision MEMS gyroscope, does not rely on the Earth's magnetic field as a positioning reference, but instead calculates geographic north by measuring the Earth's rotation angular velocity, thus avoiding magnetic field interference; at the same time, the outer shell is made of non-magnetic material, so it is not affected by magnetic fields; and by fusing real-time data from a three-axis MEMS gyroscope and a three-axis accelerometer for strapdown inertial measurement, it can perform high-precision tracking and measurement of azimuth, inclination angle, and tool face angle in real time under large random vibration conditions, which is particularly suitable for drilling measurement-while-drilling scenarios.

[0012] The drilling directional sub based on the combined use of a gyroscope and an accelerometer provided by this invention adopts an all-solid-state design, exhibiting excellent shock and vibration resistance. Under vibration conditions (randomly), it can dynamically maintain the accuracy of azimuth, inclination, and tool face angles. It achieves rapid alignment in 30 seconds with an azimuth accuracy of 1°, and precise alignment in 90 seconds with an azimuth accuracy of 0.5°. The inclination measurement angle reaches 0.1°. The gyroscope tool face angle accuracy can reach 1° / secL (L represents latitude). It can normally output azimuth and tool face angles at small inclination angles, maintaining accuracy within 3°, thus solving the technical defect of most gyroscope logging tools that cannot output effective azimuth angles in small inclination sections.

[0013] The drilling directional sub based on the combination of gyroscope and accelerometer provided by this invention has a diameter of 25.4 / 30mm and a length of 120mm, which can be easily embedded in narrow front-end spaces such as probes; it has full-temperature calibration compensation from 5 to 125℃, which ensures that the output zero bias is within the accuracy range under this temperature, and is suitable for extreme environments; The drilling directional sub based on the combination of gyroscope and accelerometer provided by this invention can quickly collect drilling data. It mainly measures the attitude information of the drilling equipment and feeds it back to the control system, thereby achieving precise control of the drilling trajectory, greatly shortening the measurement time and significantly improving the work efficiency. This invention achieves dynamic and continuous tracking measurement of well inclination angle, tool face angle, and azimuth angle through a drilling measurement system. This dynamic tracking ensures high accuracy of azimuth measurement and provides accurate guidance information for drilling operations. Attached Figure Description

[0014] Figure 1-1 This is a schematic diagram of the drilling directional sub of the present invention; Figure 1-2 This is a schematic diagram of the end face of the drilling directional sub of the present invention; Figure 2 This is a schematic diagram of the principle architecture of the present invention; Figure 3 This is a schematic diagram of the attitude and heading calculation of the present invention; Figure 4 This is a flowchart of the process of the present invention; Among them, 1 is the short section outer shell, 2 is the inner platform body, 3 is the signal processing unit, and 4 is the wiring terminal. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to embodiments. These descriptions are for illustrative purposes only and are not intended to limit the scope of the invention.

[0016] See Figure 1-1 , 1-2 , Figure 2 and Figure 3 A drilling directional sub based on the combination of a gyroscope and an accelerometer includes a sub housing 1, one end of which is sealed and the other end is a mounting reference surface. This end is also provided with a wiring terminal 4. The short section housing 1 contains an inner platform 2, on which a gyroscope, an accelerometer, and a signal processing unit are mounted, as well as a power supply module for powering them. The gyroscope and accelerometer are both arranged in three directions: x A gyroscope and an accelerometer are installed along the axial direction; y A gyroscope and an accelerometer are installed along the axial direction; z A gyroscope and an accelerometer are installed along the axial direction; the attitude, angular velocity, and linear velocity signals collected by them are sent to the signal processing unit 3 for real-time calculation. The signal processing unit 3 is connected to the host computer via a terminal block and a communication line; the signal processing unit sends the calculated well inclination angle, tool face angle and azimuth angle to the host computer.

[0017] Furthermore, the inner platform is connected to the short section outer shell by a fastener, and a shock-absorbing ring is also provided between the inner platform and the short section outer shell; The gyroscope and accelerometer are connected to the signal processing unit via SPI interface, and the signal processing unit is connected to the host computer via RS422 interface.

[0018] Furthermore, the gyroscope sensor collects the rotation angle and angular velocity of the short section and sends them to the signal processing unit; The accelerometer collects the acceleration of the short section and sends it to the signal processing unit; The signal processing unit includes a CPU microprocessor with a built-in solution unit, a filtering unit, and a calibration and optimization unit.

[0019] Furthermore, the signal processing unit filters the acquired raw data and then performs calibration; Calculate attitude angles: The signal processing unit first calculates the pitch and roll angles of the short section, which reflect the attitude of the short section. Then, it calculates the azimuth angle to determine the pointing direction of the short section. Calculate the tool face angle based on the known attitude angle and azimuth angle; The calculated azimuth and tool face angles are output to the host computer as results.

[0020] The drilling directional sub of the present invention will now be described in detail.

[0021] 1. Structural Design The outer shell is made of non-magnetic material, and the internal structure integrates an anti-vibration platform. The installation positions of the three-axis gyroscope and accelerometer, as well as the signal processing unit (PCB board), are rationally arranged. The PCB board adopts a flexible connection design to avoid messy wiring. The output interface wiring terminals use aviation waterproof connectors. The whole structure adopts a sealed structure, and the outer shell has a reference surface, which is suitable for underground operation scenarios.

[0022] Specifically, the arrangement of the three-axis gyroscope and accelerometer is as follows: x A gyroscope and an accelerometer are installed along the axis. y A gyroscope and an accelerometer are installed along the axis. z A gyroscope and an accelerometer are installed along the axis. These six components are packaged and connected to the CPU via an interface, and then placed on the PCB board. The PCB board and the inner platform are connected by a flexible connection; specifically, the PCB board and the inner platform are fixedly connected with adhesive.

[0023] The overall size is available in diameters of 25.4 / 30mm and lengths of 120mm, making it easy to fit into narrow front-end spaces such as probes and facilitating installation. One end of the housing is sealed, while the other end is designed with a reference surface (to facilitate the determination of the initial position and attitude), clearly defining the positioning reference and reducing installation errors. This end is equipped with a wiring terminal for connection to a host computer on the ground.

[0024] The drilling directional sub of this invention adopts an all-solid-state design. From the perspective of structural stability, it not only carefully sets up a shock-absorbing ring (located between the platform and the outer shell) to buffer external impacts, but also combines it with an inner platform structure to strengthen the overall support, so that its impact and vibration resistance in complex environments reaches an excellent level, which can effectively ensure the stable operation of internal components.

[0025] 2. Signal Processing The drilling directional sub of this invention mainly consists of a three-axis MEMS gyroscope sensor, three MEMS accelerometer sensors, a CPU microprocessor, a power supply circuit, and a communication circuit. Data is collected by the gyroscope sensor and the accelerometer sensor, and the CPU processes and calculates data such as azimuth angle, well inclination angle, and tool face angle to determine the precise direction of the target object.

[0026] Three-axis MEMS gyroscope sensors are primarily used to detect and measure the rotational angle and angular velocity of equipment. They measure rotational speed based on the gyroscopic effect and utilize the Coriolis force to detect the tangential force experienced by a rotating object during radial motion.

[0027] A triaxial accelerometer is used to measure the acceleration of an object and obtain acceleration information. The core component of a microprocessor that performs computational tasks often involves the calculation of trigonometric functions, such as sine, cosine, and tangent.

[0028] The signal processing unit and CPU will be further explained below.

[0029] Hardware support: The CPU microprocessor has a built-in computation unit (hardware) to accelerate mathematical calculations and uses the floating-point unit (FPU) to perform complex operations such as trigonometric functions, exponential functions, and logarithmic functions.

[0030] Solution algorithms include lookup table method, Taylor series expansion, and CORDIC algorithm; converting angles from degrees to radians, performing actual calculations using CPU hardware units and solution algorithms, and processing the calculation results as necessary to meet application requirements.

[0031] The drilling directional sub (ER-Gyro-15) of this invention uses a gyroscope sensor and an accelerometer to collect angular velocity and linear velocity, which are then processed into digital signals and connected to the CPU via an SPI interface. The CPU processes the collected data and converts it into standard RS422 protocol data, which is then sent to the host computer to display the azimuth and attitude angles.

[0032] Specifically, it uses an ARM series microcontroller to accurately calculate the real-time data collected by the gyroscope and accelerometer. The ER-Gyro-15 is equipped with an RS422 interface, which is connected to the RS422 interface of the host computer via an RS422 bus to realize data transmission.

[0033] The host computer mainly includes a communication interface, a data processing module, and a user interface. It has data acquisition and monitoring capabilities and connects to the ER-Gyro-15 through a communication interface and protocol.

[0034] like Figure 4 As shown, the working process of the drilling directional sub of the present invention is as follows: First, the entire directional sub-section workflow is started, and sensors such as gyroscopes and accelerometers are initialized to bring them into an initial state that can work normally, ensuring the accuracy and stability of subsequent data acquisition. Using the initialized sensors, relevant data from downhole is collected in real time. This data includes raw data for calculating attitude (accelerometer) and orientation (gyroscope). The collected raw data is preprocessed by filtering to remove noise interference, and then calibrated to correct possible systematic errors in the sensors and improve data quality. Attitude angle calculation: Based on the preprocessed data, the pitch angle (z-axis) and roll angle (y-axis) of the drilling sub are calculated using a solution algorithm. These two angles reflect the attitude of the sub. The azimuth angle (heading angle) is further calculated to determine the pointing direction of the sub.

[0035] Based on the known attitude angle and azimuth angle, the tool face angle is calculated; this angle plays a crucial role in the directional control of drilling. The calculated azimuth and tool face angles are output as results, providing accurate information for surface drilling guidance.

[0036] The following will illustrate this with specific application scenarios.

[0037] 1. Penetrate the blind zone of the small well. Traditional gyroscope tools have common defects in scenarios with small well inclination, such as low azimuth accuracy; however, this stage is precisely the critical period for drill bit trajectory correction, and the lack of direction perception will directly lead to trajectory deviation.

[0038] This invention employs a strapdown inertial measurement architecture combining a three-axis MEMS gyroscope and a three-axis MEMS accelerometer, which can accurately capture the minute components of the Earth's rotational angular velocity in a small wellbore inclination segment.

[0039] Strapdown inertial measurement unit (IMU) architecture is one of the core technology branches of inertial navigation system (INS). Its core feature is "no physical stabilization platform" - the inertial measurement unit (IMU, including gyroscope and accelerometer) is directly "strapdown" on the carrier. By replacing the physical stabilization platform of traditional platform-type INS through calculation, the carrier's attitude, position and velocity can be measured and calculated in real time. This invention ensures stable output of azimuth and tool face angles even at ultra-low well inclination.

[0040] When the well is inclined at 1°-2°, the azimuth accuracy should be ≤ 3°. When the well inclination is 2°-5°, the azimuth accuracy should be ≤ 2°. For well inclinations between 5° and 90°, the azimuth accuracy should be ≤ 0.5°. Operating conditions: During directional drilling, it is often necessary to adjust the azimuth angle according to the wellbore trajectory requirements. At this time, it is necessary to determine the appropriate tool face angle. For example, in a certain azimuth adjustment operation, the well depth is 1200m, the well inclination is 18°, and the azimuth is 100°, which requires increasing the inclination and decreasing the azimuth.

[0041] For example, the relevant values ​​are: the predetermined tool face is left (L) 60°, the measured tool face is left (L) 40°, the bending angle is -90°, and the estimated reverse twist angle is 35°.

[0042] Calculation process: First, calculate the actual tool face based on the bending difference angle. The formula is "Actual tool face = Measured tool face - Bending difference angle". Therefore, the actual tool face = L40° - (-90°) = R50°. Then, calculate the relative torsion angle of the drill bit according to the formula "Fixed = φ_pre- - φ_work + φ_reverse_torsion" (Fixed represents the angle of relative torsion of the drill bit, φ is the pre-prepared tool face, φ_work is the actual tool face, and φ_reverse_torsion is the reverse torsion angle). That is, Fixed = L60 - R50 + 35 = -75°.

[0043] Measures to ensure azimuth accuracy Filtering (capacitive filtering, temperature compensation based on temperature difference coefficient): Data from triaxial accelerometers and triaxial gyroscopes can be fused and compared to eliminate obviously erroneous parts; algorithms such as extended Kalman filtering are used to obtain the optimal attitude estimate and dynamically calculate the real-time attitude parameters of the drilling tool, reducing measurement errors.

[0044] Precise measurement and correction: Use high-precision inclinometers, such as multi-point inclinometers, to perform measurements, and then correct the short section (simply perform digital correction on the output value, obtain the correction coefficient, and the output result of the short section after correction is the accurate result).

[0045] Considering the impact of construction factors: In directional well construction, the reverse twist angle should be reasonably estimated based on factors such as well depth and well inclination, and corrected according to the actual measurement results. At the same time, attention should be paid to clear wellhead imprints, accurate measurement of the included angle, and determination of direction to ensure that the directional (twisting azimuth) achieves the expected results.

[0046] Solution algorithm: The azimuth estimation algorithm, such as maximum likelihood estimation and minimum variance unbiased estimation, is adopted to improve the accuracy and robustness of azimuth estimation.

[0047] Sizes range from bulky to miniature The size and weight of traditional gyroscope tools are one of their core limitations: traditional gyroscope tools are large and heavy, and cannot be adapted to small wellbores or compact drill string assemblies.

[0048] The ER-Gyro-15 features a core architecture built with carefully selected nanoscale components, leveraging the latest MEMS gyroscope technology to achieve a high-efficiency balance between miniaturization and reliability. Available in 25.4mm and 30mm diameters, with a length of only 120mm and a weight of ≤150g, this size allows for easy embedding in confined spaces such as probe tips and small drilling equipment. It solves the problem of traditional gyroscopes being unable to enter small wellbores, expanding the application scenarios of gyroscope-guided technology (such as micro-wellbore logging and small-diameter borehole guidance).

[0049] 2. Quick Alignment and Precise Alignment Traditional gyroscope tools have a long alignment time, while the ER-Gyro-15 supports both fast alignment and precise alignment modes: The rapid alignment algorithm can achieve an azimuth accuracy of 1° (1σ) in just 30 seconds. Quickly align with angular velocity data relying solely on gyroscopes, and calculate the azimuth angle through integration (accuracy is easily reduced due to accumulated integration errors); accurately perform cross-correction on the criteria fused with gyroscope and accelerometer data: Specifically, the accelerometer assists in correcting gravity direction deviation: The accelerometer can measure the gravity vector (vertically downward). If the attitude angle obtained by the gyroscope integration is inconsistent with the gravity direction sensed by the accelerometer (such as attitude angle deviation caused by integration drift), the accelerometer data is used as a reference to correct the gyroscope integration result.

[0050] Precise alignment, building upon rapid alignment, achieves an azimuth accuracy of 0.5° (1σ) after 90 seconds of precise alignment by further optimizing the algorithm and extending the data processing time.

[0051] The precise alignment mode targets the three core error sources of the gyroscope (core sensor): random noise, temperature drift, and installation error. Specific optimization directions are as follows: Filtering algorithm: Upgrade from first-order Kalman filter to adaptive extended Kalman filter (AEKF) to filter random noise; Adaptive adjustment of filter gain: Real-time analysis of the residual of the gyroscope output data, which is the difference between the predicted value and the actual acquired value; if the residual increases (such as a sudden increase in noise caused by equipment vibration), the filter gain is increased to quickly track the true value; if the residual decreases (data is stable), the gain is reduced to smooth the output and avoid overcorrection; Introducing error states: Temperature drift term and installation angle term are added after filtering, and the azimuth angle is estimated simultaneously to offset the error sources, rather than just passive filtering; Furthermore, the data processing time is extended: from single snapshot calculation to 90 seconds of multi-round iteration and data accumulation, quickly aligning and collecting 5-10 seconds of sensor data, and calculating the azimuth angle based on a single snapshot (fast but with small data volume and insufficient error suppression); the 90-second accurate alignment criterion is corrected by extending the time: the random noise and temperature drift of the gyroscope have statistical characteristics - a sufficient number of data samples are needed to estimate their distribution (such as mean and variance) through algorithms.

[0052] For example, temperature drift is not a constant value: after the device is powered on, the temperature rises from 25°C to 35°C, and the gyroscope drift rate increases from 0.1° / h to 0.3° / h. If only 10 seconds of data are collected, the relationship between "temperature and drift" cannot be captured. A 90-second acquisition process can cover the entire stage of temperature rise, allowing AEKF to fit the drift pattern more accurately, and dynamically match the real-time drift value during subsequent corrections.

[0053] Multiple rounds of iterative corrections gradually reduced the azimuth error. Precise alignment is not calculated all at once, but rather iterated over 3-5 rounds within 90 seconds, with each round optimizing based on the error results of the previous round: Round 1 (0-30 seconds): Collect basic data, use AEKF to make a preliminary estimate of the azimuth angle (accuracy of about 2°), and record the time period with large residuals (such as 10-15 seconds when noise increases due to vibration). Round 2 (30-60 seconds): For time periods with large residuals, add "local data resampling (e.g., re-filtering 10-15 seconds of data at a higher frequency)" and correct the time synchronization deviation between the accelerometer and gyroscope (fast alignment ignores small time differences, which can lead to data fusion errors). Round 3 (60-90 seconds): Use the error data from the first two rounds to optimize the magnetic field interference compensation item (such as the local magnetic field generated by metal near the equipment, quickly aligning with the uncompensated one), and finally output the azimuth angle after error convergence (accuracy up to 0.5°).

[0054] Specifically, the ER-Gyro-15 was switched from rapid alignment (10 seconds) to precise alignment (90 seconds) to meet centimeter-level trajectory control requirements. The specific optimization and correction process is shown in Table 1. Table 1 Precise Alignment Correction 3. Environmental adaptability Vibration and shock resistance: During drilling, the rotation of the drill pipe and changes in the lithology of the formation can cause severe and random vibrations. Mechanical gyroscopes are easily affected by vibrations, which can cause directional data to drift and lead to the drill bit "misjudging the direction".

[0055] The ER-Gyro-15 adopts an all-solid-state + internal platform design with no mechanical moving parts. Its impact and vibration resistance far exceeds that of traditional mechanical gyroscope tools. It can directly withstand downhole impact vibration and dynamically maintain the accuracy of azimuth, inclination, and tool face angle in random vibration environments.

[0056] Temperature adaptability: Traditional optical gyroscopes are sensitive to temperature, and their accuracy drops significantly in high-temperature environments; while the ER-Gyro-15 standard model supports an operating temperature of 5~85℃, and the high-temperature version supports 5~125℃.

[0057] Measurement Modes: From "Single Static" to "Multi-Mode Dynamic" Traditional gyroscope tools have a relatively simple measurement mode: mechanical gyroscopes support point measurement and cannot adapt to drilling scenarios; although laser gyroscopes and fiber optic gyroscopes support continuous measurement, they require complex vibration reduction and temperature control, and have high power consumption and heat generation during continuous measurement, making it difficult to work stably for a long time.

[0058] The ER-Gyro-15 supports measurement while drilling (MSW) and continuous measurement. MSW allows for real-time acquisition of borehole data and attitude parameters without interrupting drilling operations. These parameters are obtained in real-time via a three-axis gyroscope and accelerometer, including the borehole inclination angle (the angle between the borehole axis and the vertical line, determining vertical offset), azimuth angle (the angle between the projection of the borehole axis onto the horizontal plane and true north, determining horizontal offset), and tool face angle (the relative angle between the drill string guide and the borehole trajectory, directly affecting the adjustment direction). The ER-Gyro-15 outputs real-time inclination and vertical depth data through drill string length counting (combined with the length of drill pipe pushed to the surface) and accelerometer integration. When the vertical depth approaches the design target (e.g., 10 meters from the target vertical depth), it automatically issues a warning and reduces drill pressure and rotational speed to prevent over-drilling.

[0059] Specific embodiments are given below. 1. Application scenarios in geological exploration 1) Breakthrough in Orientation under Strong Magnetic Interference Environments: In the exploration of a metal ore body in Xinjiang, the magnetic interference intensity in densely casing areas exceeded 3000 nT, rendering traditional fluxgate sensors completely ineffective. The ER-Gyro-15 achieved true north orientation using a three-axis MEMS gyroscope, with a measured azimuth accuracy consistently maintained at 0.5°secψ(1σ). A 100% success rate was achieved in 30 seconds of rapid alignment, representing a 400% improvement in efficiency compared to traditional methods.

[0060] 2) Small well inclination layer control: Optimization for well inclination layer of 0.1°~90°: 0.1°~2° ultra-low inclination well section: azimuth accuracy controlled within 3° 5°~90° conventional well section: accuracy improved to 0.5° Dynamic continuous measurement function realizes real-time tracking of borehole trajectory. After application in a mining area in Xinjiang, the trajectory deviation rate was reduced to 2.3%.

[0061] 2. Oilfield drilling application scenarios 1) Precision anti-collision system: In the construction of cluster wells in Karamay oilfield, the tool face angle measurement accuracy reached 1° / secL, successfully achieving precise anti-collision at a well spacing of 3m, reducing the accident rate by 90%.

[0062] 2) Trajectory control optimization: In conjunction with the automatic guidance system, a trajectory control accuracy of 0.2° / 10m is achieved in the 30°~60° well inclination section, saving 18 hours of drilling cycle per well.

[0063] 3. Application scenarios of underground engineering in coal mines 1) Anti-interference measurement while drilling: In the tunnel excavation of a coal mine in Shanxi, the ER-Gyro-15 still maintained an azimuth accuracy of 1° under strong electromagnetic interference environment (magnetic field strength 1500nT), and the 30s rapid north-finding function improved the tunneling efficiency by 35%.

[0064] 2) Miniaturization and adaptation advantages: The 25.4mm diameter design is successfully embedded into a Φ28mm mining drill rod, enabling full-face coverage measurement within a 5m×5m roadway.

[0065] The embodiments given above are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions or substitutions made by those skilled in the art based on the technical features of the present invention are within the protection scope of the present invention.

Claims

1. A drilling directional sub based on the combined use of a gyroscope and an accelerometer, characterized in that, It includes a short section housing, one end of which is sealed, and the opposite end is a mounting reference surface, which is also provided with a wiring terminal; The short section housing contains an inner platform, on which a gyroscope, accelerometer, and signal processing unit are mounted, along with a power supply module that powers them. The gyroscope and accelerometer are both arranged in three directions: x A gyroscope and an accelerometer are installed along the axial direction; y A gyroscope and an accelerometer are installed along the axial direction; z A gyroscope and an accelerometer are installed along the axis; the attitude, angular velocity, and linear velocity signals collected by them are sent to the signal processing unit for real-time calculation. The signal processing unit is connected to the host computer via a terminal block and a communication line; the signal processing unit sends the calculated well inclination angle, tool face angle and azimuth angle to the host computer.

2. The drilling directional sub based on the combined use of a gyroscope and an accelerometer as described in claim 1, characterized in that, The inner platform is connected to the short section outer shell by a fastener, and a shock-absorbing ring is also provided between the inner platform and the short section outer shell; The gyroscope and accelerometer are connected to the signal processing unit via SPI interface, and the signal processing unit is connected to the host computer via RS422 interface.

3. The drilling directional sub based on the combined use of a gyroscope and an accelerometer as described in claim 1, characterized in that, The gyroscope sensor collects the rotation angle and angular velocity of the short section and sends them to the signal processing unit; The accelerometer collects the acceleration of the short section and sends it to the signal processing unit; The signal processing unit includes a CPU microprocessor with a built-in solution unit, a filtering unit, and a calibration and optimization unit.

4. The drilling directional sub based on the combined use of a gyroscope and an accelerometer as described in claim 3, characterized in that, The signal processing unit filters the acquired raw data and then performs calibration. Calculate attitude angles: The signal processing unit first calculates the pitch and roll angles of the short section, which reflect the attitude of the short section. Then, it calculates the azimuth angle to determine the pointing direction of the short section. Calculate the tool face angle based on the known attitude angle and azimuth angle; The calculated azimuth and tool face angles are output to the host computer as results.

5. The drilling directional sub based on the combined use of a gyroscope and an accelerometer as described in claim 4, characterized in that, The filtering unit is a first-order Kalman filter or an extended Kalman filter. The calibration optimization is based on the comparison of measurement results from prior instruments to obtain correction coefficients; and introduces temperature drift terms, installation angle terms, and magnetic field interference compensation terms.

6. The drilling directional sub based on the combined use of a gyroscope and an accelerometer as described in claim 1 or 4, characterized in that, The signal processing unit's calculations include a fast alignment mode and a precise alignment mode; The fast alignment mode relies solely on the angular velocity data from the gyroscope, and calculates the azimuth angle through integration. Precise cross-correction of criterion mode fusion gyroscope and accelerometer: Accelerometers can measure the gravity vector. If the attitude angle obtained by integrating the gyroscope is inconsistent with the direction of gravity sensed by the accelerometer, the accelerometer data is used as a reference to correct the gyroscope integration result.

7. The drilling directional sub based on the combined use of a gyroscope and an accelerometer as described in claim 6, characterized in that, The filtering algorithm for the fast alignment mode uses a first-order Kalman filter algorithm; The filtering algorithm for the criterion mode is an adaptive extended Kalman filter algorithm; and the filter gain is adaptively adjusted: the residual of the gyroscope output data is analyzed in real time, which is the difference between the predicted value and the actual acquired value; if the residual increases, the filter gain is increased to quickly track the true value; if the residual decreases, the gain is decreased to smooth the output. Error states are also introduced: temperature drift term and installation angle term are added after filtering, and azimuth angle is estimated simultaneously to offset error sources.

8. The drilling directional sub based on the combined use of a gyroscope and an accelerometer as described in claim 7, characterized in that, The precise criterion model also iterates 3-5 times within 0 seconds, with each round optimizing based on the error results of the previous round: In the first round, from 0 to 30 seconds, basic data is collected, and the azimuth angle is initially estimated using an extended Kalman filter. At the same time, the time periods with larger residuals are recorded. In the second round, from 30 to 60 seconds, local data resampling was added for the time period with large residuals, and the time synchronization deviation between the accelerometer and the gyroscope was corrected. In the third round, from 60 to 90 seconds, the error data from the first two rounds is used to optimize the magnetic field interference compensation term, and the final output is the azimuth angle after the error convergence.

Images