Device and method for evaluating stratum properties by measuring near-bit data at high frequency

Abstract

The invention discloses a device and method for evaluating stratum properties by measuring near-bit data at high frequency, and relates to the technical field of stratum evaluation while drilling, and the device comprises an axial force measuring probe which is arranged at the rear part of a cutting tooth and can be in contact with the surface of a rock mass when the rock mass is cut by the cutting tooth; the packaging type measuring unit is arranged in the drill bit and is connected with the axial force measuring probe; the packaging type measuring unit comprises a data acquisition module used for acquiring axial force time sequence data acquired by an axial force measuring probe, and three-axis acceleration time sequence data, three-axis magnetic field intensity time sequence data and rotating speed time sequence data acquired by an internal sensor; and the data processing system is used for evaluating stratum properties according to the axial force time sequence data, the three-axis acceleration time sequence data, the three-axis magnetic field intensity time sequence data and the rotating speed time sequence data. The method does not depend on special equipment or independent construction operation, and is not interfered by factors such as mud types and borehole sizes.

Description

Technical Field

[0001] This application relates to the field of formation evaluation technology while drilling, and in particular to an apparatus and method for evaluating formation properties by high-frequency measurement of near-bit data. Background Technology

[0002] As oil and gas exploration deepens, reservoir conditions become more complex, placing higher demands on the accuracy, real-time performance, and adaptability of drilling-while-drilling (DWD) formation assessment technologies. Furthermore, with drilling costs gradually decreasing, construction costs and timelines are also being compressed. Traditional downhole imaging technologies mainly include wireline logging and DWD, both of which require specialized equipment or separate operations, increasing construction costs and timelines.

[0003] Logging while drilling (LOW) and wireline logging are effective methods for assessing downhole geological structure and composition; however, both methods have certain limitations. LOW imaging depends on the type of drilling mud, is limited by wellbore size, requires additional equipment, affects drilling fluid circulation, has high measurement equipment costs, requires additional personnel, and can easily interfere with normal drilling operations. Wireline logging imaging is only applicable to completed wellbores, is susceptible to wellbore integrity, does not reflect the original formation state, is typically performed separately after drilling completion, lacks real-time capability, requires drilling interruption, increases overall operation time, and necessitates well cleaning and logging before and after operation, resulting in high overall costs and added risks. Summary of the Invention

[0004] The purpose of this application is to provide an apparatus and method for evaluating formation properties by measuring near-bit data at high frequency, which does not rely on proprietary equipment or separate construction operations and is not affected by factors such as mud type and wellbore size.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a device for evaluating formation properties by measuring near-bit data at high frequency, comprising: an axial force measuring probe and an encapsulated measuring unit; The axial force measuring probe is positioned at the cutter wing of the drill bit and is located at the rear of the cutting teeth; the protrusion height of the axial force measuring probe is configured such that when the cutting teeth are cutting the rock, the axial force measuring probe can contact the surface of the rock. An encapsulated measurement unit is built into the drill bit and connected to the axial force measurement probe; The packaged measurement unit includes: The data acquisition module is used to acquire the axial force time-series data obtained by the axial force measurement probe, as well as the triaxial acceleration time-series data, triaxial magnetic field strength time-series data, and rotational speed time-series data obtained by the internal sensors; The data processing system is used to evaluate the formation properties based on the axial force time series data, the triaxial acceleration time series data, the triaxial magnetic field strength time series data, and the rotational speed time series data.

[0006] Optionally, the diameter of the axial force measuring probe is the same as the diameter of the cutting tooth, and it is made of high-strength wear-resistant material and is not axially extensible.

[0007] Optionally, the encapsulated measuring unit is sealed in a pressure-resistant chamber and connected to the axial force measuring probe through a wiring channel located inside the drill bit.

[0008] Optionally, the packaged measurement unit includes: A triaxial accelerometer is used to measure the triaxial acceleration timing data of a drill bit. A gyroscope is used to measure the timing data of the drill bit's rotational speed. A magnetometer is used to measure the timing data of the triaxial magnetic field strength of a drill bit.

[0009] Optionally, the packaged measurement unit further includes a power supply device and a data storage module.

[0010] Secondly, this application provides a method for evaluating formation properties using high-frequency measurement of near-bit data, including: The downhole measurement data includes: axial force time-series data, triaxial acceleration time-series data, triaxial magnetic field strength time-series data, and rotational speed time-series data. The axial force time-series data is acquired by an axial force measurement probe mounted on the drill bit blade. The axial force measurement probe is positioned at the rear of the cutting tooth, and its exposure height is configured to contact the surface of the rock mass when the cutting tooth is cutting the rock mass. The triaxial acceleration time-series data, the triaxial magnetic field strength time-series data, and the rotational speed time-series data are acquired by internal sensors of a packaged measurement unit. The rotation period of the drill bit is determined based on the changes in the horizontal component in the time series data of the triaxial magnetic field strength. Based on the rotation cycle, the axial force time series data is divided into cycles to obtain a single-cycle dataset corresponding to each rotation cycle; the single-cycle dataset includes: single-cycle axial force time series data, single-cycle triaxial acceleration time series data, and single-cycle rotational speed time series data; For each rotation cycle corresponding to a single-cycle dataset, combined with the corresponding azimuth information calculated based on the magnetic field strength time series data, a time stratigraphic map is generated with time and azimuth as coordinate axes and axial force amplitude as the characterization of image intensity.

[0011] Optionally, after generating a temporal stratigraphic map with time and azimuth as coordinate axes and axial force amplitude representing image intensity for each single-cycle dataset corresponding to each rotation cycle, and combining the corresponding azimuth information calculated based on the magnetic field strength time-series data, the method further includes: Acquire surface drilling data; the surface drilling data includes: time, drilling pressure, rotation speed, and drilling depth; Based on the surface drilling data, it is determined whether the drill bit has experienced torsional vibration. After determining that torsional vibration has occurred, the data sampling amount for each azimuth interval is determined based on the integral ratio of the rotational speed in different azimuth intervals within the rotational cycle.

[0012] Optionally, after generating a temporal stratigraphic map with time and azimuth as coordinate axes and axial force amplitude representing image intensity for each rotation cycle's single-cycle dataset, combined with the corresponding azimuth information calculated based on the magnetic field strength time-series data, the method further includes: Based on the time alignment relationship between the surface drilling data and the downhole measurement data, the time coordinates of the time-stratigraphic map are converted into depth coordinates to generate a depth-stratigraphic map with depth and azimuth as coordinate axes. Based on the image intensity changes in the depth stratigraphic map, the evaluation results of stratigraphic properties and structure are output.

[0013] Optionally, for each rotation cycle corresponding to a single-cycle dataset, combined with the corresponding azimuth information calculated based on the magnetic field strength time-series data, a time-stratigraphic map is generated, with time and azimuth as coordinate axes and axial force amplitude representing image intensity. Specifically, this includes: Obtain wellbore dip angle information; When the wellbore inclination angle is less than or equal to a preset threshold, the magnetic north orientation method is adopted, and the magnetic north direction is determined as the azimuth reference based on the three-axis magnetic field strength time series data. When the wellbore dip angle is greater than the preset threshold, the wellbore high-side orientation method is adopted, and the wellbore high-side direction is determined as the azimuth reference based on the radial component in the triaxial acceleration time series data. Based on the azimuth reference, for each rotation cycle corresponding to a single-cycle dataset, and combined with the corresponding azimuth information calculated from the magnetic field strength time series data, a time stratigraphic map is generated with time and azimuth as coordinate axes and axial force amplitude as the characterization of image intensity.

[0014] Optionally, the magnetic north orientation method is as follows: identify the moment when the horizontal component in the triaxial magnetic field strength time series data reaches its maximum value and the horizontal component is zero, and determine the orientation of the probe at this moment as the magnetic north direction. According to the specific embodiments provided in this application, this application has the following technical effects: This application provides an apparatus and method for evaluating formation properties using high-frequency near-bit data measurement. The apparatus includes: an axial force measurement probe and an encapsulated measurement unit; the axial force measurement probe is disposed at the cutter wing position of the drill bit and located behind the cutting teeth; the exposure height of the axial force measurement probe is configured such that it can contact the surface of the rock mass when the cutting teeth are cutting the rock mass; the encapsulated measurement unit is built into the drill bit and connected to the axial force measurement probe; wherein, the encapsulated measurement unit includes: a data acquisition module for acquiring axial force time-series data obtained by the axial force measurement probe, and triaxial acceleration time-series data, triaxial magnetic field strength time-series data, and rotational speed time-series data obtained by internal sensors; and a data processing system for evaluating formation properties based on the axial force time-series data, the triaxial acceleration time-series data, the triaxial magnetic field strength time-series data, and the rotational speed time-series data. This application mounts the axial force measuring probe on the drill bit blades and integrates a packaged measuring unit inside the drill bit, eliminating the need for additional equipment and reducing construction difficulty. The drill bit directly contacts the rock formation while rotating and breaking it, collecting axial force and other relevant parameters, thus avoiding interference from factors such as mud type and wellbore size. Furthermore, the device can measure the interaction force with the rock formation in real time, allowing drilling operations to continue without interruption and eliminating the influence of factors such as wellbore diameter reduction. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a device for evaluating formation properties by measuring near-bit data at high frequency, as provided in an embodiment of this application.

[0017] Figure 2 This is a schematic diagram illustrating the overall process of data analysis using a device for evaluating formation properties based on high-frequency near-bit measurement data, as provided in an embodiment of this application.

[0018] Figure 3 This is a schematic diagram illustrating the variation of formation structure with well depth, as provided in an embodiment of this application.

[0019] Figure 4 A top view of a PDC drill bit provided in an embodiment of this application.

[0020] Figure 5 This is a schematic diagram illustrating the interaction between the cutting teeth, the axial force measuring probe, and the rock mass, as provided in an embodiment of this application.

[0021] Figure 6 This is a schematic diagram of the structure of a packaged measurement unit provided in an embodiment of this application.

[0022] Figure 7 A schematic diagram of the rotation trajectory of an axial force measuring probe provided in another embodiment of this application.

[0023] Figure 8 A schematic diagram illustrating the determination of the magnetic north pole in another embodiment of this application.

[0024] Figure 9 This is a schematic diagram of a time-studded map based on data, provided as another embodiment of this application.

[0025] Figure 10 This is a schematic diagram of a data-based deep stratigraphic map provided in another embodiment of this application.

[0026] Figure 11 This is a schematic diagram illustrating the variation of formation structure with well depth, provided for another embodiment of this application.

[0027] Reference numerals: 1-Axial force measuring probe, 2-Connecting line, 3-Drill bit, 4-Encapsulated measuring unit, 5-Encapsulated measuring unit housing, 6-Cutting teeth, 7-Rock mass, 8-PDC line channel. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] This application proposes a device and method for evaluating formation properties using high-frequency near-bit data measurement. The method is simple to operate, requires no additional procedures, and does not interfere with normal drilling operations. To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] In one exemplary embodiment, such as Figure 1 As shown, a device for evaluating formation properties by measuring near-bit data at high frequency is provided, including: an axial force measuring probe 1 and a packaged measuring unit 4.

[0031] The axial force measuring probe 1 is located at the blade position of the drill bit 3 (a PDC drill bit is selected in this embodiment) and at the rear of the cutting tooth 6; the protrusion height of the axial force measuring probe 1 is configured such that when the cutting tooth 6 cuts the rock body 7, the axial force measuring probe 1 can contact the surface of the rock body 7.

[0032] The encapsulated measuring unit 4 is built into the drill bit 3 and connected to the axial force measuring probe 1. It is connected via a connecting line 2.

[0033] The packaged measurement unit 4 includes: The data acquisition module is used to acquire the axial force time-series data obtained by the axial force measuring probe 1, as well as the triaxial acceleration time-series data, triaxial magnetic field strength time-series data and rotational speed time-series data obtained by the internal sensors; The data processing system is used to evaluate the formation properties based on the axial force time series data, the triaxial acceleration time series data, the triaxial magnetic field strength time series data, and the rotational speed time series data.

[0034] In this embodiment, by adjusting the structure of drill bit 3 and installing an axial force measuring probe 1 at drill bit 3, the probe interacts with the rock mass 7 during the drilling process of drill bit 3. As drill bit 3 continues to drill, the probe continuously contacts the rock mass 7, thereby allowing the change in the properties of the encountered formation rock mass 7 and the structure of the formation to be determined by the change in axial force. Based on the axial force data, combined with vibration acceleration, rotational speed, and reference logging imaging principles, the time-series data is converted into a formation map, enabling the determination and study of formation properties.

[0035] This embodiment features a novel drill bit 3 structure and a downhole data acquisition unit, such as... Figure 1 As shown. First, the structure of drill bit 3 is adjusted, and axial force measuring probe 1 (high-strength probe) is installed at the rear of cutting teeth 6. The probe is in contact with the rock mass 7, thereby collecting axial stress at high frequency. The data measured during drilling is stored inside the encapsulated measuring unit 4. After the drill is pulled out, the internal data is read using a laptop to determine the changes in the formation structure and composition by stress changes.

[0036] Based on measurement data from instruments such as axial force measuring probe 1, accelerometer (triaxial accelerometer), gyroscope, and magnetometer, a multi-dimensional data coupling analysis method was established in conjunction with surface drilling data. The analysis process is as follows: Figure 2 As shown in the figure. Changes in rock strata are sensed by variations in axial force, azimuth is assessed using a magnetometer, and a formation property discrimination method is established by referencing imaging logging methods. Subsequently, acceleration and rotation speed are used to further refine the assessment results. Combined with surface drilling data, changes in formation properties are discriminated based on both time and depth. Specific results are shown in the figure. Figure 3 As shown.

[0037] Specifically: 1. Measurement Unit Design: (1) Adjust the structure of drill bit 3 and design an axial force measuring probe 1 at the position of the PDC drill bit blade. The probe is installed at the rear of the PDC cutting teeth, and its diameter is the same as that of the PDC cutting teeth, thereby avoiding the probe being subjected to lateral impact from the rock mass 7. The probe is made of high-strength wear-resistant material and is not axially retractable. The PDC cutting teeth directly cut the rock mass 7, forming a cutting trajectory. The probe's exposed height is slightly higher than that of the PDC cutting teeth, thereby ensuring that it makes direct and slight contact with the rock mass 7 during the rotation of drill bit 3. The specific structure is as follows: Figure 4 As shown.

[0038] During the rotation of drill bit 3, cutting teeth 6 cut into rock mass 7, forming a cutting trajectory. Since the probe's exposed height is slightly higher than the PDC drill bit, the probe contacts the surface of rock mass 7. The probe slightly brushes against the surface of rock mass 7, generating an axial force. When the composition or structure of the rock strata changes, the interaction force between the two changes. Therefore, the change in contact force can be used to determine whether the properties of the encountered rock strata have changed. The interaction between the axial force probe and rock mass 7 is as follows: Figure 5 As shown.

[0039] (2) Packaged measurement unit 4, which integrates a triaxial accelerometer, gyroscope, magnetometer, as well as power supply and storage devices, such as Figure 6 As shown, this unit is built into the rear of the drill bit 3 and connected to the axial force measuring probe 1 to provide power and data storage. It can be installed in time before drilling, and the data can be directly read by the PC host computer software after drilling is completed, followed by data analysis and formation identification and evaluation. The encapsulated measuring unit 4 is sealed in a pressure-resistant chamber (encapsulated measuring unit chamber 5) and connected to the axial force measuring probe 1 through the PDC line channel 8 located inside the drill bit 3.

[0040] 2. Data Collection: The sensors in the drill bit 3's cutter wings will collect the axial force Fz generated by the interaction between the axial force measurement probe 1 and the formation in real time at high frequency during drilling; at the same time, the triaxial acceleration (α) of the drill bit 3 will be directly measured by the triaxial accelerometer. x , a y ,a z The magnetometer directly measures the triaxial magnetic field strength (M) of drill bit 3. x M y M z The gyroscope directly measures the rotational speed R of the drill bit 3, and this dynamic data will be stored in memory. As the strata change, the interaction force between the probe and the rock mass 7 changes accordingly; high-frequency sampling ensures that subtle strata changes are captured.

[0041] The triaxial accelerometer and gyroscope can reflect the vibration state of the drill bit during drilling and whether abnormal vibration occurs, thus providing a reference for data analysis and correcting errors in the data analysis results.

[0042] The magnetometer can capture changes in magnetic field strength during the rotation of drill bit 3, providing a basis for determining the rotation cycle of drill bit 3. Simultaneously, it can be combined with surface drilling data to establish stratigraphic variation maps along the time and depth axes, enabling the analysis of stratigraphic characteristics, fractures, and rock structure.

[0043] The device provided in this embodiment has extremely strong environmental adaptability. The drill bit 3 is in contact with the rock mass 7 and is completely unaffected by the type, density, or salinity of the drilling mud. It is suitable for various drilling fluids such as water-based mud and oil-based mud, and can be applied to wellbores of different sizes. It is adaptable to various drilling scenarios such as onshore, offshore, vertical, and horizontal wells.

[0044] This method does not affect drilling operations and can simplify the operational process. The sensor used in this method is integrated into the drill bit 3 body, eliminating the need for additional measuring devices and maintaining the bottom drill string assembly sequence and overall performance. It also does not alter the original drilling parameters and operational procedures, while ensuring the mechanical drilling speed, stability, and directional control capabilities of the drill bit 3.

[0045] In another exemplary embodiment, a method for evaluating formation properties by measuring near-bit data at high frequency is provided, comprising: S1. Acquire downhole measurement data; the downhole measurement data includes: axial force time-series data, triaxial acceleration time-series data, triaxial magnetic field strength time-series data, and rotational speed time-series data; the axial force time-series data is acquired by an axial force measurement probe mounted on the drill bit blade; the axial force measurement probe is located at the rear of the cutting tooth, and its exposure height is configured to contact the surface of the rock mass when the cutting tooth cuts the rock mass; the triaxial acceleration time-series data, the triaxial magnetic field strength time-series data, and the rotational speed time-series data are acquired by internal sensors of the encapsulated measurement unit.

[0046] The formation properties encountered by the drill bit are a key factor influencing the characteristics of axial force. For example, the higher the formation strength, the greater the overall value of the axial force; while rocks exhibiting brittle failure will produce more random transient fluctuations in the force signal due to the rock fracturing process under the action of the cutting teeth. This method analyzes the data to generate formation property discrimination maps (time-stratigraphic maps) with time and azimuth as coordinate axes and formation property discrimination maps (depth-stratigraphic maps) with depth and azimuth as coordinate axes.

[0047] S2. Determine the rotation period of the drill bit based on the changes in the horizontal component in the time series data of the triaxial magnetic field strength.

[0048] S3. Based on the rotation cycle, the axial force time series data is divided into cycles to obtain a single-cycle dataset corresponding to each rotation cycle; the single-cycle dataset includes: single-cycle axial force time series data, single-cycle triaxial acceleration time series data, and single-cycle rotational speed time series data.

[0049] In this embodiment, the drill bit rotation cycle is first identified, and the data is then categorized by azimuth angle, such as... Figure 7 The specific process is as follows: ① During rotation, the magnetometer readings change periodically with the drill bit's rotation. Keeping the magnetometer horizontal (Z-axis perpendicular to the ground) and rotating it one revolution around the vertical axis, the vertical component Mz of the Earth's magnetic field remains essentially constant, while the horizontal components Mx and My change periodically with the rotation angle. Therefore, by observing the changes in the magnetometer's horizontal component readings, the drill bit's rotation period T can be determined, and the data on axial force, acceleration, and rotational speed can be segmented based on the time required for each revolution of the drill bit.

[0050] ② Preprocess the axial force time series data, triaxial acceleration time series data, triaxial magnetic field strength time series data, and rotational speed time series data to remove outliers, delete trend terms, and perform filtering.

[0051] ③ The magnetometer has three built-in, mutually perpendicular Hall effect sensors that measure the magnetic field strength (directed vector) along their respective directions. The magnitude of the vector sum represents the strength of the Earth's magnetic field, and its direction represents the direction of the magnetic field (magnetic north pole). Assuming the device is horizontal and the magnetometer's coordinates are aligned with the horizontal plane, the azimuth angle α (relative to magnetic north) can be calculated using two-axis components: (1) S4. For each rotation cycle corresponding to a single-cycle dataset, and in conjunction with the corresponding azimuth information calculated based on the magnetic field strength time series data, a time stratigraphic map is generated with time and azimuth as coordinate axes and axial force amplitude as the characterization of image intensity.

[0052] ④ Process and analyze the data. Normalize the data based on the magnitude of the axial force amplitude. Combine this with a color spectrum, using color depth to represent the magnitude of the axial force amplitude, and use plotting software to draw the azimuth value α, time t, and axial force F. z The two-dimensional map uses azimuth as the horizontal axis and axial force as the vertical axis. The magnitude of the corresponding axial force is selected to represent the depth of color. Thus, the magnitude of the axial force at different times and locations, and the changes in the properties of the rock strata, can be determined based on the changes in the color intensity of the map.

[0053] ⑤ Analyze the vibration state of the drill bit during drilling to determine whether torsional vibration has occurred, and further optimize the image based on fluctuations in acceleration and rotational speed. A gyroscope can directly measure the rotational speed at the drill bit; therefore, combining this with surface drilling data can determine whether torsional vibration has occurred. ; (2) in This represents the maximum drill bit rotation speed within the cycle. This represents the minimum rotational speed within the cycle. The ground rotational speed within the period. Torsional vibration occurs when the SSI value is greater than 0. When the value equals 0, stick-slip vibration occurs, and the drill bit stops rotating. At this point, the drill bit's orientation remains unchanged, and careful processing of the collected axial force data is necessary.

[0054] If no torsional vibration occurs during rotation, the rotational speed is constant, and the data sampling volume at different azimuths is equal. When torsional vibration occurs, the rotational speed fluctuates significantly, and the dwell time of the drill bit at different azimuths varies during one revolution. Since the sensor sampling frequency is constant, the amount of data measured at different azimuths differs. The period time is divided into N equal parts, and the rotational speed is integrated, based on the same time interval... The ratio of the integral values ​​of the internal rotational speed is used to determine the sampling amount in different azimuth intervals.

[0055] ; (3) ; (4) For example, dividing the rotation period into four equal parts allows us to determine the amount of data for each of the four time periods based on the integral ratio of the rotation speed. However, the amount of data within the same time period is not the same, so processing is necessary. When the rotation speed is high, the interval swept by the drill bit in the same time period is large; conversely, when the rotation speed is low, the interval swept by the drill bit in the same time period is small. For data lacking sufficient quantity, interpolation is used to supplement the data; for oversampled data, the mean of the data is selected for analysis.

[0056] ⑥ Different orientation methods are adopted for different wellbore dip angles. Magnetic north orientation is used for vertical well sections and low-inclination sections. The magnetic north direction is obtained by combining a magnetometer with a geomagnetic model for correction. Figure 8 As shown. Before drilling, the wellbore structure design needs to be completed. During the drilling process, drilling construction needs to be carried out according to the design. Therefore, it is possible to know the well inclination angle at different depths and positions, and determine whether the section is a vertical section or a horizontal section, or a low inclination angle or a high inclination angle.

[0057] The magnetic field vector can be decomposed into two components parallel to the local horizontal plane and one component perpendicular to the local horizontal plane. For the two horizontal components, their vector sum always points towards the magnetic north pole. Therefore, the data processing can be performed using M... x The measured values ​​are used as the basis for periodic judgment. When the measuring unit reaches a certain position as the drill string rotates, M is... y M is zero. x When the maximum value is reached, this direction can be considered the magnetic north pole.

[0058] The inclined and horizontal sections of the wellbore are oriented using the high side of the wellbore. The position of the high side is determined by the radial acceleration value measured by an accelerometer, thus ensuring the accuracy of spatial positioning of geological features. The accelerometer is built into the measurement unit. When the accelerometer points to the high side, the radial acceleration value is positive; when the accelerometer points to the low side, the radial acceleration value is negative.

[0059] In this embodiment, rock mass properties are assessed and relevant images are generated using data collected from one revolution of the drill bit. Data collected at the magnetic north pole and the high edge of the wellbore is used as a starting point to generate images of the rock mass surrounding the drill bit after one revolution.

[0060] ⑦ The measuring device continuously collects data during the drilling process. The images generated by each drill bit revolution are stacked and integrated to form a formation image along the wellbore trajectory, such as... Figure 9 As shown.

[0061] (2) Depth-azimuth mapping combines well logging data from surface drilling with time-based mapping to create a formation image in depth coordinates. The vertical axis represents depth, the horizontal axis represents azimuth, and the magnitude of axial force indicates the intensity of the mapping. The data analysis process is as follows: Figure 10 As shown.

[0062] ① Summarize surface drilling data, including time, rotation speed, and drilling pressure (DPS). Based on DPS, rotation speed, and drilling speed, determine the drilling status during the drilling process, discard invalid data, and retain valid data. DPS, rotation speed, and drilling speed are parameters measured by other relevant drilling equipment and are basic parameters in current oil drilling, requiring no additional measurement.

[0063] ② Align the surface drilling data and downhole measurement data based on the time axis, and correlate the axial force data, triaxial acceleration, magnetometer data with the well depth to clarify the well depth location for data acquisition.

[0064] ③ By analyzing ground measurement data, determine the change in drill bit position over time to ascertain the drilling depth. Then, use the averaging method to determine the change in drilling depth per unit time. Based on the start and end times of one drill bit rotation, combined with ground data measurement results, determine the start and end positions of the drill bit for each or multiple cycles using timestamps.

[0065] ④ Based on the drill bit's drilling depth, azimuth variation, and axial force, the time map is converted into a depth map, thereby establishing the variation of formation properties with well depth, such as... Figure 11 As shown, the depth map is a graph plotted with depth on the vertical axis and azimuth on the horizontal axis, showing the variation of axial force F throughout the entire rock-breaking cycle of the drill bit rotation. This graph can reflect the amplitude of axial force F at different azimuths and depths.

[0066] When drawing the image, the starting position of the drill bit's rotation is used as the vertical axis and the orientation within the rotation cycle is used as the horizontal axis to draw the change of axial force within a single rotation cycle; then the change of axial force in the next cycle is drawn, and interpolation is used to supplement the difference between different depths; then the image is rendered to finally form a depth map of drilling depth-orientation-axial force.

[0067] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0068] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0069] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0070] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A device for evaluating formation properties by measuring near-bit data at high frequency, characterized in that, include: Axial force measurement probe and encapsulated measurement unit; The axial force measuring probe is positioned at the cutter wing of the drill bit and is located at the rear of the cutting teeth; The exposure height of the axial force measuring probe is configured such that when the cutting teeth are cutting the rock mass, the axial force measuring probe can contact the surface of the rock mass; An encapsulated measurement unit is built into the drill bit and connected to the axial force measurement probe; The packaged measurement unit includes: The data acquisition module is used to acquire the axial force time-series data obtained by the axial force measurement probe, as well as the triaxial acceleration time-series data, triaxial magnetic field strength time-series data, and rotational speed time-series data obtained by the internal sensors; The data processing system is used to evaluate the formation properties based on the axial force time series data, the triaxial acceleration time series data, the triaxial magnetic field strength time series data, and the rotational speed time series data.

2. The apparatus for evaluating formation properties by measuring near-bit data using high-frequency measurements according to claim 1, characterized in that, The diameter of the axial force measuring probe is the same as the diameter of the cutting tooth, and it is made of high-strength wear-resistant material and is not axially extensible.

3. The apparatus for evaluating formation properties by measuring near-bit data using high-frequency measurements according to claim 1, characterized in that, The encapsulated measuring unit is sealed inside a pressure-resistant chamber and connected to the axial force measuring probe via a wiring channel located inside the drill bit.

4. The apparatus for evaluating formation properties by measuring near-bit data using high-frequency measurements according to claim 1, characterized in that, The packaged measurement unit includes: A triaxial accelerometer is used to measure the triaxial acceleration timing data of a drill bit. A gyroscope is used to measure the timing data of the drill bit's rotational speed. A magnetometer is used to measure the timing data of the triaxial magnetic field strength of a drill bit.

5. The apparatus for evaluating formation properties by measuring near-bit data according to claim 4, characterized in that, The packaged measurement unit also includes a power supply device and a data storage module.

6. A method for evaluating formation properties using high-frequency near-bit measurement data, characterized in that, include: Acquire downhole measurement data; The downhole measurement data includes: axial force time-series data, triaxial acceleration time-series data, triaxial magnetic field strength time-series data, and rotational speed time-series data; the axial force time-series data is acquired by an axial force measurement probe mounted on the drill bit blade; the axial force measurement probe is positioned at the rear of the cutting teeth, and its exposure height is configured to contact the surface of the rock mass when the cutting teeth are cutting the rock mass; the triaxial acceleration time-series data, the triaxial magnetic field strength time-series data, and the rotational speed time-series data are acquired by internal sensors of the encapsulated measurement unit; The rotation period of the drill bit is determined based on the changes in the horizontal component in the time series data of the triaxial magnetic field strength. Based on the rotation cycle, the axial force time series data is divided into cycles to obtain a single-cycle dataset corresponding to each rotation cycle; the single-cycle dataset includes: single-cycle axial force time series data, single-cycle triaxial acceleration time series data, and single-cycle rotational speed time series data; For each rotation cycle corresponding to a single-cycle dataset, combined with the corresponding azimuth information calculated based on the magnetic field strength time series data, a time stratigraphic map is generated with time and azimuth as coordinate axes and axial force amplitude as the characterization of image intensity.

7. The method for evaluating formation properties using high-frequency near-bit measurement data according to claim 6, characterized in that, After generating a time-stratigraphic map with time and azimuth as coordinate axes and axial force amplitude representing image intensity for each rotation cycle's single-cycle dataset, combined with the corresponding azimuth information calculated based on the magnetic field strength time-series data, the process further includes: Acquire surface drilling data; the surface drilling data includes: time, drilling pressure, rotation speed, and drilling depth; Based on the surface drilling data, it is determined whether the drill bit has experienced torsional vibration. After determining that torsional vibration has occurred, the data sampling amount for each azimuth interval is determined based on the integral ratio of the rotational speed in different azimuth intervals within the rotational cycle.

8. The method for evaluating formation properties using high-frequency near-bit measurement data according to claim 7, characterized in that, After generating a time-stratigraphic map with time and azimuth as coordinate axes and axial force amplitude representing image intensity for each rotation cycle's single-cycle dataset, combined with the corresponding azimuth information calculated based on the magnetic field strength time-series data, the process further includes: Based on the time alignment relationship between the surface drilling data and the downhole measurement data, the time coordinates of the time-stratigraphic map are converted into depth coordinates to generate a depth-stratigraphic map with depth and azimuth as coordinate axes. Based on the image intensity changes in the depth stratigraphic map, the evaluation results of stratigraphic properties and structure are output.

9. The method for evaluating formation properties using high-frequency near-bit measurement data according to claim 7, characterized in that, For each rotation cycle corresponding to a single-cycle dataset, combined with the corresponding azimuth information calculated based on the magnetic field strength time-series data, a time-stratigraphic map is generated, with time and azimuth as coordinate axes and axial force amplitude representing image intensity. Specifically, this includes: Obtain wellbore dip angle information; When the wellbore inclination angle is less than or equal to a preset threshold, the magnetic north orientation method is adopted, and the magnetic north direction is determined as the azimuth reference based on the three-axis magnetic field strength time series data. When the wellbore dip angle is greater than the preset threshold, the wellbore high-side orientation method is adopted, and the wellbore high-side direction is determined as the azimuth reference based on the radial component in the triaxial acceleration time series data. Based on the azimuth reference, for each rotation cycle corresponding to a single-cycle dataset, and combined with the corresponding azimuth information calculated from the magnetic field strength time series data, a time stratigraphic map is generated with time and azimuth as coordinate axes and axial force amplitude as the characterization of image intensity.

10. The method for evaluating formation properties using high-frequency near-bit measurement data according to claim 9, characterized in that, The magnetic north orientation method is as follows: identify the moment when the horizontal component in the three-axis magnetic field strength time series data reaches its maximum value and the horizontal component is zero, and determine the orientation of the probe at this moment as the magnetic north direction.

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