Magnetic three-component measuring device in well

Abstract

The invention discloses a downhole magnetic three-component measuring device, and relates to the technical field of metal mineral drilling exploration. The swinging mechanism is arranged in the sealing pipe in a swinging manner and comprises a swinging block; the horizontal holding mechanism is connected to the swinging mechanism and comprises a holding piece and a magnetic sensor assembly arranged on the holding piece; the retaining piece is connected with the swing block through the rotating shaft, so that when the swing mechanism swings, the surface of the retaining piece can be automatically kept horizontal under the action of gravity. According to the in-well magnetic three-component measuring device, no matter how the inclination angle and the orientation of the sealing pipe change, the swing block and retainer assembly continuously swings and rotates, and finally, the measuring reference surface of the retainer is dynamically and automatically calibrated to the local horizontal plane; the real-time output of the magnetic sensor assembly is a horizontal magnetic field component and a vertical magnetic field component in a geographic coordinate system at a measuring point, the conversion error caused by inaccurate inclination angle measurement is eliminated, and the precision is ensured.

Description

Technical Field

[0001] This invention relates to the field of borehole exploration technology for metal mineral resources, and in particular to a borehole magnetic three-component measurement device. Background Technology

[0002] In the exploration of metallic minerals, especially magnetite, borehole magnetic surveying is an important geophysical method. Essentially, it involves measuring the geomagnetic field vectors (usually decomposed into three mutually perpendicular components, namely the magnetic triad X, Y, and Z) at different depths within the borehole to analyze and infer the occurrence and occurrence of ore bodies in the strata penetrated by the borehole, as well as to detect concealed blind ore bodies beside or at the bottom of the borehole. The horizontal components X and Y are primarily used to analyze changes in the horizontal direction of the magnetic field, while the vertical component Z is particularly sensitive for identifying vertically magnetized bodies. By processing these raw magnetic component data, vector maps can be drawn, providing crucial information for geological interpretation. Furthermore, in weakly magnetic strata, the horizontal components X and Y of the magnetic field are sometimes used to assist in analyzing the borehole's own dip and azimuth.

[0003] Currently, most widely used borehole magnetic three-component sensors are "axial magnetic three-component sensors." Their working principle is as follows: the sensor measures magnetic field values ​​in three directions within the borehole, but these three directions are relative to the sensor's coordinate system (usually related to the probe axis). Since the borehole is not perfectly vertical, but has an inclination angle and azimuth, the sensor's attitude (tilt angle, azimuth angle) changes with depth. Therefore, the directly measured X, Y, and Z values ​​are not the true horizontal and vertical components relative to the horizontal plane and geodetic position required for geological interpretation.

[0004] To obtain geologically meaningful true values, current technologies require complex data conversions. The specific process involves simultaneously measuring the magnetic three components and using tilt sensors to measure the sensor's attitude (tilt angle and azimuth) in the well in real time. Then, in the later data processing stage, these attitude measurement data are used to convert the measurements from the sensor coordinate system to the horizontal geographic coordinate system using coordinate rotation transformation formulas, yielding the true horizontal (X, Y) and vertical (Z) components. This process heavily relies on the accuracy of the tilt measurement.

[0005] However, in actual well operations, the probe is prone to swaying, collisions, or rotation during hoisting or lowering, especially in irregular sections or when encountering obstructions. This motion disturbance severely affects the accuracy of dip angle measurements, leading to errors in the attitude angle data. These attitude angle errors are propagated and amplified during coordinate conversion, ultimately distorting the calculated true magnetic three-component (X, Y, Z) data. This distortion directly impacts the reliability of subsequent vector plotting and geological interpretation, potentially causing incorrect orebody location, inaccurate reserve estimations, or even ore leakage.

[0006] Therefore, there are still shortcomings and deficiencies in the existing technology. There is an urgent need in the field for a measurement device that can directly obtain the true horizontal and vertical magnetic field components from the physical measurement level, so as to get rid of the dependence on real-time, high-precision attitude measurement, thereby simplifying the process, reducing error sources, and improving the credibility of the final interpretation results. Summary of the Invention

[0007] The purpose of this invention is to provide a borehole magnetic three-component measurement device, which solves the technical problem that existing borehole magnetic three-component sensors must measure the sensor's attitude in the borehole in real time and use a coordinate rotation transformation formula to convert the measured value into the true magnetic three components. This process is complex and cannot guarantee measurement accuracy.

[0008] To achieve the above objectives, the present invention provides a well-drilled magnetic three-component measuring device, comprising:

[0009] Sealed tube;

[0010] A swing mechanism, which is swingably disposed inside the sealed tube, includes a swing block;

[0011] A horizontal holding mechanism, connected to the swing mechanism, includes a holding member and a magnetic sensor assembly disposed on the holding member; the holding member is connected to the swing block via a rotating shaft, so that when the swing mechanism swings, the surface of the holding member can automatically remain horizontal under the action of gravity;

[0012] The magnetic sensor assembly includes sensors for sensing magnetic fields in three mutually orthogonal directions, and when the surface of the retainer is kept horizontal, the sensing directions of two sensors are located in the horizontal plane, and the sensing direction of the third sensor is perpendicular to the horizontal plane.

[0013] In some technical solutions, the swing block has an internal cavity, and the retainer is connected to the two side walls of the internal cavity of the swing block by two rotating shafts, the axis of the rotating shafts being coincident with the rotation axis of the retainer.

[0014] In some technical solutions, the magnetic sensor assembly includes three independent magnetic sensors, which respectively sense a first horizontal magnetic field, a second horizontal magnetic field, and a vertical magnetic field; the three magnetic sensors are fixedly disposed on the surface of the retainer, and the sensing direction of the sensor sensing the first horizontal magnetic field is consistent with the direction of the rotation axis of the retainer.

[0015] In some technical solutions, the swing mechanism further includes:

[0016] An adjusting element is located at the bottom of the sealing tube, and the bottom of the swing block is supported on the adjusting element;

[0017] A current collector ring, used to realize the electrical connection between the magnetic sensor assembly and the external measurement circuit, includes a fixed part at the upper end and a rotating part at the lower end. The fixed part is fixed to the sealing tube, and the rotating part is connected to the upper part of the swing block.

[0018] In some technical solutions, the adjusting element is an adjusting screw, which is threadedly connected to the bottom center of the sealing tube.

[0019] In some technical solutions, a cover plate is fixedly provided on the top of the sealing tube, and the fixing part of the collecting ring is sealed to the cover plate.

[0020] In some technical solutions, the magnetic sensor assembly is mounted on a circuit board, the circuit board is fixed to the surface of the retainer, and the circuit board is connected to the current collector ring via a signal connector.

[0021] In some technical solutions, the rotation axis of the collector ring and the support point of the bottom of the swing block on the adjusting member are located on the same axis.

[0022] In some technical solutions, the bottom center of the swing block extends towards one side of the adjusting member to form a protrusion, and the swing block is supported on the adjusting member through the protrusion.

[0023] In some technical solutions, the sealed tube is filled with damping fluid.

[0024] Compared to the aforementioned background technology, the well magnetic three-component measurement device provided by this invention, regardless of how the tilt angle and orientation of the sealing tube change, the internal swing block and retainer assembly, through continuous swinging and rotation, will eventually dynamically and automatically calibrate the measurement reference plane of the retainer to the local horizontal plane. The real-time output of the magnetic sensor assembly, namely the horizontal magnetic field component and the vertical magnetic field component in the geographic coordinate system at the measurement point, completely eliminates the conversion error introduced by inaccurate tilt angle measurement, ensuring the highest accuracy from the data source, and eliminating the need for a sophisticated electronic tilt angle measurement unit and related complex data processing algorithms. Attached Figure Description

[0025] 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This is a cross-sectional view of the well magnetic three-component measurement device provided in an embodiment of the present invention.

[0027] Figure 1 Chinese reference numerals: 1. Sealing tube; 2. Swing block; 21. Inner cavity; 22. Protrusion; 3. Holding part; 4. Rotating shaft; 5. Adjusting part; 6. Current collector ring; 61. Fixing part; 62. Rotating part; 7. Circuit board; 8. Signal connector; 9. Cover plate. Detailed Implementation

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

[0029] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] This invention provides a three-component magnetic measurement device for wells. The real-time output of the magnetic sensor component is the horizontal and vertical magnetic field components in the geographic coordinate system at the measurement point, which completely eliminates the conversion error caused by inaccurate inclination measurement, ensuring the highest accuracy from the data source, and eliminating the need for a sophisticated electronic inclination measurement unit and related complex data processing algorithms.

[0031] Please refer to Figure 1 The well magnetic three-component measuring device provided by the present invention includes:

[0032] Sealing tube 1;

[0033] The swing mechanism is swingably disposed inside the sealed tube 1, and includes a swing block 2;

[0034] A horizontal holding mechanism is connected to the swing mechanism, including a holding member 3 and a magnetic sensor assembly disposed on the holding member 3; the holding member 3 is connected to the swing block 2 through a rotating shaft 4, so that when the swing mechanism swings, the surface of the holding member 3 can automatically remain horizontal under the action of gravity;

[0035] The magnetic sensor assembly includes sensors for sensing magnetic fields in three mutually orthogonal directions, and when the surface of the retainer 3 is kept horizontal, the sensing directions of two sensors are located in the horizontal plane, and the sensing direction of the third sensor is perpendicular to the horizontal plane.

[0036] The sealing tube 1, serving as the external main body of the in-well magnetic three-component measurement device, has a tubular structure and is typically made of materials such as stainless steel. It is used to withstand downhole pressure and isolate media such as drilling mud. A swinging mechanism is oscillatingly mounted inside the sealing tube 1. It mainly includes a swing block 2, a mass block that can swing freely within the sealing tube 1, made of a high-density, hard metal such as brass or iron-tungsten alloy. A horizontal holding mechanism is connected to the swinging mechanism and includes a holding member 3 and a magnetic sensor assembly mounted on the holding member 3. The holding member 3 is rotatably connected to the swing block 2 via a rotating shaft 4. The holding member 3 is also made of a high-density, hard metal such as brass or iron-tungsten alloy.

[0037] When the sealing tube 1 tilts due to the drilling tilt, the swing block 2 will swing around its support point under the action of gravity to seek a stable position with the lowest center of gravity. At the same time, the retaining member 3, which is suspended on the swing block 2 by the rotating shaft 4, will rotate relative to the swing block 2 under its own weight until its surface (usually the upper surface) is adjusted to a horizontal state. This is a completely passive process based on the balance of gravity and torque. In addition, the weight of the left and right ends of the swing block 2 is exactly the same, which further ensures the sensitivity of the magnetic three-component measuring device when measuring the magnetic field.

[0038] The magnetic sensor assembly includes sensors that sense magnetic fields in three mutually orthogonal directions in space. When the surface of the retainer 3 is automatically kept horizontal, the sensitive axes of two sensors in the magnetic sensor assembly are precisely located in the surface plane of the retainer 3 (i.e., measuring the true horizontal magnetic field X and Y components), while the sensitive axis of the third sensor is strictly perpendicular to the plane (i.e., measuring the true vertical magnetic field Z component).

[0039] During downhole measurements, regardless of the tilt angle and orientation of the sealing tube 1, the internal oscillating block 2 and retainer 3 assembly continuously oscillate and rotate, eventually causing the measuring reference plane of retainer 3 to dynamically and automatically calibrate to the local horizontal plane. Therefore, the three electrical signals output in real time by the magnetic sensor assembly can directly and accurately correspond to the horizontal and vertical magnetic field components in the geographic coordinate system at the measurement point.

[0040] This configuration ensures that the measurement plane of the magnetic sensor assembly is physically parallel to the horizontal plane of the earth. The output of the magnetic sensor assembly directly reflects the true horizontal and vertical components, completely eliminating conversion errors introduced by inaccurate tilt measurements and guaranteeing the highest accuracy from the data source. It eliminates the need for a sophisticated electronic tilt measurement unit and related complex data processing algorithms. The core stabilization mechanism is purely mechanical and passive, independent of electronic sensors and software algorithms susceptible to temperature and vibration, exhibiting strong anti-interference capabilities and making it particularly suitable for harsh downhole environments characterized by high temperature, high pressure, and strong vibration.

[0041] In some embodiments, the swing block 2 has an inner cavity 21 inside, and the retainer 3 is connected to the two side walls of the inner cavity 21 of the swing block 2 by two rotating shafts 4, and the axis of the rotating shafts 4 coincides with the rotation axis of the retainer 3.

[0042] Please refer to Figure 1 The swing block 2 has an inner cavity 21 inside, and the retainer 3 is housed in this inner cavity 21 and connected to the left and right side walls of the inner cavity 21 by two rotating shafts 4. The axes of the two rotating shafts 4 are collinear and coincide with the rotation axis of the retainer 3 itself. The rotating shafts 4 can be installed using precision bearings or low-friction bushings to ensure that the retainer 3 can rotate flexibly around the shafts.

[0043] This configuration provides mounting space for the retainer 3 through the inner cavity 21, resulting in a compact structure. Furthermore, the enclosed structure of the inner cavity 21 better protects the retainer 3 and the magnetic sensor assembly mounted on the retainer 3.

[0044] In some embodiments, the magnetic sensor assembly includes three independent magnetic sensors, which respectively sense a first horizontal magnetic field, a second horizontal magnetic field, and a vertical magnetic field; the three magnetic sensors are fixedly disposed on the surface of the holder 3, and the sensing direction of the sensor that senses the first horizontal magnetic field is consistent with the direction of the rotation axis of the holder 3.

[0045] Please refer to Figure 1 In this embodiment, the magnetic sensor assembly includes three independent magnetic sensors that respectively measure the magnetic field in a first horizontal direction (e.g., defined as a direction parallel to the rotation axis of the retainer 3), a second horizontal direction orthogonal to it, and a vertical direction. These three sensors are securely mounted on the surface of the retainer 3. During installation, it must be ensured that the sensor measuring the first horizontal direction has its sensitive axis aligned with the rotation axis of the retainer 3 (i.e., the direction of the rotation axis 44).

[0046] In some embodiments, the swing mechanism further includes:

[0047] Adjusting component 5 is located at the bottom of sealing tube 1, and the bottom of swing block 2 is supported on adjusting component 5;

[0048] The current collector ring 6 is used to realize the electrical connection between the magnetic sensor assembly and the external measurement circuit. It includes a fixed part 61 at the upper end and a rotating part 62 at the lower end. The fixed part 61 is fixed to the sealing tube 1, and the rotating part 62 is connected to the upper part of the swing block 2.

[0049] Please refer to Figure 1The swing mechanism also includes an adjusting member 5 and a current collector ring 6. The adjusting member 5 is installed at the bottom of the sealing tube 1, and the bottom of the swing block 2 is directly supported on the adjusting member 5. This contact point constitutes the actual pivot point for the swing of the swing block 2. The current collector ring 6 is used to power the moving magnetic sensor assembly and transmit signals. It includes a fixed part 61 at the upper end and a rotating part 62 at the lower end. The fixed part 61 is fixedly connected to the sealing tube 1; the rotating part 62 is connected to the upper part of the swing block 2, so that the rotating part 62 can rotate freely about its own axis, while allowing the swing block 2 to swing relative to it.

[0050] The axial position and initial state of the swing block 2 can be finely adjusted by adjusting component 5. The current collector ring 6 can transmit electrical signals from the fixed sealing tube 1 to the moving swing block 2 and the retaining component 3, while minimizing mechanical interference to the degree of freedom of the swing block 2 under gravity. Its rotating part 62 is allowed to rotate around the axis to release the cable torque that may be generated due to the swing, and to avoid wire entanglement or the generation of counter-torque that hinders the swing.

[0051] In some embodiments, the adjusting member 5 is an adjusting screw, which is threaded to the bottom center of the sealing tube 1.

[0052] Please refer to Figure 1 In this embodiment, the adjusting component 5 can be an adjusting screw. The adjusting screw is installed at the bottom center of the sealing tube 1 through a threaded connection, and the adjusting screw is sealed to the sealing tube 1.

[0053] By using the adjusting screw, the height of its top end can be easily and precisely adjusted by rotating it, thereby changing the axial position of the swing block 2 in the sealing tube 1, ensuring that its swing space is appropriate, and reducing the damping of the swing block 2 swinging left and right.

[0054] In some embodiments, a cover plate 9 is fixedly provided on the top of the sealing tube 1, and the fixing part 61 of the collecting ring 6 is sealed to the cover plate 9.

[0055] Please refer to Figure 1 At the top center of the sealing tube 1, a cover plate 9 is fastened to it by welding or other fixing methods. The fixing part 61 of the collector ring 6 passes through the cover plate 9 and achieves a sealing connection with the cover plate 9 (such as by O-rings or sealant).

[0056] With this configuration, the sealing connection between the fixing part 61 of the collecting ring 6 and the cover plate 9 not only fixes the collecting ring 6, but also ensures the overall sealing performance of the sealing pipe 1, preventing the intrusion of liquids (mud, water) in the well and protecting the internal precision mechanism.

[0057] In some embodiments, the magnetic sensor assembly is mounted on the circuit board 7, which is fixed to the surface of the retainer 3, and the circuit board 7 is connected to the current collector ring 6 via the signal connector 8.

[0058] Please refer to Figure 1 The magnetic sensor assembly and some necessary electronic components are soldered onto a circuit board 7, which can be fixed to the surface of the retainer 3 by means of adhesive or screws. Electrical signals from the circuit board 7 are led out through a signal connector 8 and connected to the power lines and signal transmission lines on the slip ring 6. The integrated circuit board 7 improves the reliability and compactness of the circuit. The signal connector 8 is selected for its low insertion / extraction force and small size to minimize the resistance torque on the rotational movement of the retainer 3 and ensure the sensitivity of horizontal holding.

[0059] In some embodiments, the rotation axis of the collector ring 6 and the support point of the bottom of the swing block 2 on the adjusting member 5 are located on the same axis.

[0060] Please refer to Figure 1 The mechanical rotation axis of the collector ring 6 and the support point of the bottom of the swing block 2 on the adjusting member 5 are precisely located on the same vertical axis, ensuring that the swing block 2 can swing without jamming. If they are not on the same axis, the swing block 2 will be subjected to additional lateral constraint force or torsional torque when swinging, generating unnecessary friction, increasing swing damping, and reducing the system's response speed and sensitivity to tilt changes.

[0061] In some embodiments, the bottom center of the swing block 2 extends toward the adjusting member 5 to form a protrusion 22, and the swing block 2 is supported on the adjusting member 5 by the protrusion 22.

[0062] Please refer to Figure 1 The bottom center of the swing block 2 extends downward to form a cylindrical protrusion 22. The end of the swing block 2 contacts the top of the adjusting screw through the end of this protrusion 22, forming a point contact or a small surface contact.

[0063] By setting the protrusion 22, the support contact area is minimized, which greatly reduces the sliding friction at the swing fulcrum. This makes the swing block 2 more sensitive and smooth under gravity drive, and can respond more accurately to the slight tilt changes of the sealing tube 1. This is beneficial for keeping the retainer 3 in a high-precision horizontal state.

[0064] In some embodiments, the sealing tube 1 is filled with damping fluid.

[0065] In order to suppress the continuous oscillation or high-frequency vibration of the swing block 2 and the retainer 3 that may be caused by complex downhole movements (such as probe collision, sudden stop, etc.), the cavity inside the sealing tube 1 is filled with damping fluid, which is usually silicone oil with a certain viscosity.

[0066] The damping fluid surrounds the moving parts (oscillating block 2 and retainer 3), which must overcome the viscous resistance of the silicone oil when they oscillate or rotate. This viscous damping effectively absorbs and dissipates the extra kinetic energy from accidental impacts, allowing the system to quickly decay oscillations after being disturbed and smoothly and rapidly return to the equilibrium position without prolonged back-and-forth oscillations. This ensures stable and reliable instantaneous readings in dynamic downhole environments, improving the repeatability and accuracy of measurements.

[0067] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0068] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A three-component magnetic measurement device for wells, characterized in that, include: Sealing tube (1); The swing mechanism is swingably disposed inside the sealed tube (1) and includes a swing block (2); A horizontal holding mechanism is connected to the swing mechanism, including a holding member (3) and a magnetic sensor assembly disposed on the holding member (3); the holding member (3) is connected to the swing block (2) via a rotating shaft (4), so that when the swing mechanism swings, the surface of the holding member (3) can automatically remain horizontal under the action of gravity; The magnetic sensor assembly includes sensors for sensing magnetic fields in three mutually orthogonal directions, and when the surface of the retainer (3) is kept horizontal, the sensing directions of two sensors are in the horizontal plane, and the sensing direction of the third sensor is perpendicular to the horizontal plane.

2. The well magnetic three-component measuring device according to claim 1, characterized in that, The swing block (2) has an inner cavity (21) inside. The retainer (3) is connected to the two side walls of the inner cavity (21) of the swing block (2) through two rotating shafts (4). The axis of the rotating shafts (4) coincides with the rotation axis of the retainer (3).

3. The well magnetic three-component measuring device according to claim 1, characterized in that, The magnetic sensor assembly includes three independent magnetic sensors, which respectively sense the first horizontal magnetic field, the second horizontal magnetic field, and the vertical magnetic field. The three magnetic sensors are fixed on the surface of the retainer (3), and the sensing direction of the sensor that senses the first horizontal magnetic field is consistent with the direction of the rotation axis of the retainer (3).

4. The well magnetic three-component measuring device according to claim 1, characterized in that, The swing mechanism also includes: An adjusting member (5) is provided at the bottom of the sealing tube (1), and the bottom of the swing block (2) is supported on the adjusting member (5); The current collector ring (6) is used to realize the electrical connection between the magnetic sensor assembly and the external measurement circuit. It includes a fixed part (61) at the upper end and a rotating part (62) at the lower end. The fixed part (61) is fixed to the sealing tube (1), and the rotating part (62) is connected to the upper part of the swing block (2).

5. The well magnetic three-component measuring device according to claim 4, characterized in that, The adjusting component (5) is an adjusting screw, which is threaded to the bottom center of the sealing tube (1).

6. The well magnetic three-component measuring device according to claim 4, characterized in that, The top of the sealing tube (1) is fixedly provided with a cover plate (9), and the fixing part (61) of the collecting ring (6) is sealed to the cover plate (9).

7. The well magnetic three-component measuring device according to claim 4, characterized in that, The magnetic sensor assembly is mounted on the circuit board (7), which is fixed to the surface of the retainer (3). The circuit board (7) is connected to the current collector ring (6) via a signal connector (8).

8. The well magnetic three-component measuring device according to claim 4, characterized in that, The rotation axis of the collector ring (6) and the support point of the bottom of the swing block (2) on the adjusting member (5) are on the same axis.

9. The well magnetic three-component measuring device according to claim 8, characterized in that, The bottom center of the swing block (2) extends toward the adjustment member (5) to form a protrusion (22), and the swing block (2) is supported on the adjustment member (5) by the protrusion (22).

10. The well magnetic three-component measuring device according to claim 1, characterized in that, The sealing tube (1) is filled with damping fluid.

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