Structural design of paramagnetic density source bin

Abstract

The invention relates to the technical field of oil well logging, and provides a magnetophilic density source bin structural design which comprises an instrument shell, a source chamber pin, a magnetophilic cover plate, a fastening screw, a source chamber body, a density source, a source bin screw and a ray window, a T-shaped groove is formed in the magnetophilic cover plate, the source chamber body is arranged in the T-shaped groove, and the density source is arranged in the T-shaped groove. The source chamber main body is fixed on the paramagnetic cover plate through the fastening screw, and the density source is arranged in the source chamber main body; the upper side of the paramagnetic cover plate is rotatably connected with the instrument shell through the source chamber pin, and the lower side of the paramagnetic cover plate is arranged on the instrument shell through the source chamber screw; the ray window is arranged on the instrument shell through a rolling shaft pin, the ray window is located below the source chamber main body, the ray emitting direction of the ray window is tightly attached to the stratum, and the opening direction of the source chamber main body is back to the stratum. The method has the effects of improving the safety of density logging and reducing the well falling probability of the source chamber.

Description

Technical Field

[0001] This application relates to the field of oil well logging technology, and in particular to a magnetic density source chamber structure design. Background Technology

[0002] In oil well logging technology, the radiometric density logging tool is a core device for measuring formation density. Its principle is based on the Compton scattering effect of gamma rays with the formation. Medium-energy gamma rays emitted from radioactive sources such as cesium-137 or cobalt-60 penetrate the formation. The detector receives the intensity of the scattered rays, and the formation volume density is inferred through energy spectrum analysis. This parameter plays a crucial role in reservoir evaluation, porosity calculation, and oil and gas reservoir development decisions. In recent years, with the surge in exploration demand for unconventional oil and gas (such as shale gas and tight oil) and deep-sea oil and gas resources, the logging environment has become increasingly complex (high temperature and high pressure, highly deviated wells, ultra-deep wells), placing higher demands on the reliability of the instruments.

[0003] Major international service companies (such as Schlumberger's HLDT and Halliburton's FDC) generally adopt push-type density logging tool designs, using a robotic arm to press the detector module against the wellbore to improve measurement accuracy. However, the security of radioactive source encapsulation remains a pain point in the industry—globally, there are more than 20 logging interruptions each year due to source chamber accidents, with each accident causing an average economic loss of over $3 million (including salvage costs, environmental remediation, and project delays). Traditional solutions focus on material upgrades (such as using high-density tungsten alloy shielding) and structural reinforcement (such as increasing the number of fasteners), but fail to fundamentally solve the problem of recyclability after source chamber detachment.

[0004] Existing technologies mainly adopt three technical approaches to address source chamber security issues: (1) Mechanical fixing scheme: A multi-stage fastening structure combination is adopted, such as the "double screw + locating pin" design proposed in US Patent US7820969B2. The source chamber is fixed by two M8 stainless steel screws and Φ5mm hardened steel pins, and high-temperature resistant thread-locking adhesive (Loctite272) is applied to the threaded parts. The advantage of this scheme is that the shear strength can reach 12kN, which can withstand the severe downhole vibration; the disadvantage is that the magnetic permeability of tungsten-nickel-iron alloy (density 18.5g / cm³) is only 1.05μH / m, which cannot respond to the 1.5T magnetic field of the strong magnetic retriever. When the screws break due to fatigue, the source chamber will sink to the bottom of the well in a free fall manner.

[0005] (2) Friction optimization scheme: As described in Chinese patent CN104632181A, a diamond-like carbon (DLC) film is coated on the outer surface of the source chamber to reduce the coefficient of friction (from 0.6 to 0.15), and the opening and closing surface of the source chamber is designed as a 45° inclined plane to avoid the well wall protrusion. This method can extend the life of the source chamber by 30%, but it cannot solve the problem of instantaneous impact load (measured up to 500G) caused by the irregularity of the wellbore. This impact will cause the screw with a preload of 25 N·m to loosen and fall off within 200 hours.

[0006] (3) Redundancy backup scheme: A typical example is the "fractured fuse" design (WO2017146782A1) adopted by Shell, which adds a titanium alloy weak connection between the source chamber and the instrument body. When the main fixed structure fails, the fuse breaks, triggering an acoustic alarm, while maintaining the connection between the source chamber and the cable. This technology increases the success rate of retrieval to 40%, but increases the system complexity by 50%, and requires modification of the wellhead blowout preventer assembly to accommodate the emergency cable retrieval function.

[0007] The existing technology mainly suffers from the following systemic defects: ① Material property contradiction: There is a fundamental conflict between the gamma-ray shielding efficiency of high atomic number materials (such as tungsten) (90% attenuation requires a thickness of 15 mm) and their magnetizability. The magnetization of existing source chamber materials is less than 1 emu / g, resulting in the effective adsorption force of the strong magnetic retrieval device (NdFeB permanent magnet) being less than 5 N, which is only 6% of the source chamber's own weight (about 8 kg).

[0008] ② Mechanical design flaws: The traditional ground-hugging opening and closing structure causes the source chamber screw to directly bear the friction force of the well wall. Actual measurement data shows that under the conditions of a well depth of 6000 meters and a dogleg angle of 15° / 30m, a single screw is subjected to an average of 3000 cycles of load per day, and the preload decay rate reaches 0.5 N·m / hour.

[0009] ③ Limited failure mode: 82% of well falls are caused by a chain reaction of "loose screws - source chamber lifting - getting stuck in the well wall" (BP 2019 Accident Report). Existing designs lack failure-guided mechanisms, and once the initial fastening fails, it leads to complete detachment.

[0010] ④ Human-machine interaction risk: The source installation process requires operators to manually unscrew the screws, which takes an average of 8 minutes per time, resulting in a cumulative radiation dose of 50 μSv per time (equivalent to 5 times that of a chest X-ray). Existing quick-release structures generally sacrifice the function of preventing misoperation, and there have been cases of immediate well-falling accidents caused by incomplete locking (ExxonMobil 2021 case).

[0011] ⑤ Insufficient environmental adaptability: In deep-sea conditions, traditional metallic materials are prone to stress corrosion cracking (SCC) in chloride ion environments. Failure analysis of a South China Sea oilfield showed that 304 stainless steel fasteners exhibited a crack propagation rate of 0.1 mm / kWh in a salinity environment of 15,000 ppm. Therefore, there is an urgent need for a logging instrument that can increase the safety of density logging and facilitate retrieval after the source chamber is dropped into the well. Summary of the Invention

[0012] To improve the safety of density logging and reduce the probability of source chamber falling into the well, this application provides a magnetically affinity density source chamber structure design.

[0013] The magnetic density source chamber structure design provided in this application adopts the following technical solution: A magnetic density source chamber structure design includes an instrument housing, a source chamber pin, a magnetic cover plate, fastening screws, a source chamber body, a density source, source chamber screws, and a radiation window. The magnetic cover plate has a T-slot, and the source chamber body is disposed within the T-slot. The source chamber body is fixed to the magnetic cover plate by the fastening screws, and the density source is disposed within the source chamber body. The upper side of the magnetic cover plate is rotatably connected to the instrument housing via the source chamber pin, and the lower side of the magnetic cover plate is disposed on the instrument housing via the source chamber screws. The radiation window is disposed on the instrument housing via a rolled shaft pin, and is located below the source chamber body. The direction in which the radiation emitted from the radiation window is close to the ground, and the opening direction of the source chamber body faces away from the ground.

[0014] By adopting the above technical solution, the source chamber body is connected to the magnetically attached cover plate via a T-slot and fixed with two M8 fastening screws, thus integrating the source chamber body and the magnetically attached cover plate into one unit. The upper side of the magnetically attached cover plate is connected to the instrument housing via a source chamber pin, and the lower side is fixed to the instrument housing via source chamber screws. The X-ray window is fixed to the instrument housing via two rolled shaft pins.

[0015] During the logging process with a density logging tool, the radiation beam must be fired in close contact with the formation. The connection between the radiation window and the instrument housing ensures proper penetration of the radiation beam into the formation. Compared to previous density logging tools, the opening and closing direction of the source chamber body has changed from being flush with the formation to facing away from it. This effectively reduces wear on the source chamber body caused by friction and prevents accidents caused by the source chamber body piercing the well wall due to loose or detached source chamber screws. Furthermore, the addition of a magnetically-friendly cover plate to the source chamber body allows for retrieval using strong magnets even in the event of a source chamber falling into the well, reducing retrieval difficulty, time, and economic losses.

[0016] Preferably, it also includes an elastic washer, which is fitted onto the fastening screw, and the fastening screw is coated with thread-locking adhesive.

[0017] By adopting the above technical solution, the elastic washer, fitted onto the fastening screw, can compensate for the assembly gap of the connecting parts and buffer vibration and impact through its own elastic deformation, effectively preventing the screw from loosening due to long-term stress or vibration; while the thread adhesive applied to the fastening screw can fill the thread gap after curing, enhance the locking force between the threads, and at the same time have the functions of sealing and preventing leakage and preventing corrosion. The combination of the two can significantly improve the stability, sealing and durability of the connection structure, ensuring that the fastening parts remain reliably fixed for a long time.

[0018] Preferably, it also includes a coiled pin, which is located on one side of the fastening screw and is used to connect the magnetic cover plate and the instrument housing. The diameter of the coiled pin is 5 mm.

[0019] By adopting the above technical solution, the coiled pin further connects the magnetic cover plate and the instrument housing together, which can further improve the stability of the magnetic cover plate and play a double insurance role.

[0020] Preferably, it also includes a screw spring, which is sleeved on the source chamber screw.

[0021] By adopting the above technical solution, the screw spring can compensate for the small gaps during assembly by means of its own elastic deformation energy, buffer the vibration and impact force generated during the use of the magnetic cover plate, and continuously provide a stable preload force, effectively preventing the source chamber screw from loosening due to long-term force fluctuations or vibrations, ensuring the connection stability between the magnetic cover plate and the instrument housing, and extending the service reliability of the overall structure.

[0022] When loading the source, loosen the source chamber screw using the hexagonal end of the universal source gun, and hook the source gun lifting hook onto the lifting hole on the magnetophilic cover to open the source chamber. At this time, the source chamber screw will spring up under the elastic action of the source chamber screw spring, which can make room for loading the universal source gun and facilitate the loading of the source. Moreover, since the magnetophilic cover has the same type of thread as the source chamber screw, it can prevent the source chamber screw from falling off after it springs up, preventing the source chamber screw from falling off or being lost due to operator negligence or error. At the same time, it can reduce the operator's source loading time, reduce the difficulty of operation, and reduce the irradiation time.

[0023] Preferably, the connection strength between the source chamber body and the magnetophilic cover plate is greater than the strength of the source chamber pin.

[0024] By adopting the above technical solution, in some application scenarios, even if the source chamber screws are not tightened due to operational errors or loosened due to vibration, causing the source chamber cover to open and the magnetic cover plate (end A) to pierce the well wall, the magnetic cover plate and the source chamber body will rotate counterclockwise around the source chamber pin together. During this process, the source chamber body will rotate together with the magnetic cover plate (end B) through the T-slot of the magnetic cover plate. The two M8 fastening screws only serve a connecting function and are not subjected to shear force, preventing the source chamber body from separating from the magnetic cover plate due to shearing breakage of the fastening screws, which would increase the difficulty of retrieval. The coiled pin has the same function as the two M8 fastening screws in this process, providing double protection.

[0025] The connection strength between the source chamber body and the magnetically attached cover plate is greater than the strength of the source chamber pin, allowing the source chamber pin to be cut first, causing the magnetically attached cover plate to detach together with the source chamber body. This overall magnetic connection allows for retrieval using strong magnetic force, reducing the difficulty of retrieval. This design not only significantly improves the success rate of retrieval operations but also greatly shortens the time required for retrieval, thereby effectively reducing the environmental pollution risks and economic losses caused by the radioactive source remaining at the bottom of the well.

[0026] Preferably, the magnetic cover plate is made of a high saturation permeability alloy with a magnetization intensity ≥80 emu / g and a thickness of 8-12 mm.

[0027] By adopting the above technical solution, the magnetically attracted cover plate is made of high saturation magnetic permeability alloy material, with a high magnetization intensity of ≥80 emu / g and a thickness of 8-12mm. It can not only efficiently concentrate the magnetic field and reduce magnetic field leakage to ensure the stable performance of the magnetic properties of related equipment, but its high magnetization intensity also allows the cover plate to quickly respond to strong magnetic adsorption, realizing a convenient strong magnetic retrieval function. At the same time, the thickness of 8-12mm ensures the structural strength of the cover plate itself and provides reliable physical support for magnetic adsorption and retrieval, ultimately balancing the protection of the magnetic properties of the equipment and the convenience of later maintenance.

[0028] Preferably, it also includes an anti-detachment component, which connects the magnetic cover plate and the instrument housing to prevent the magnetic cover plate from detaching from the instrument housing; the anti-detachment component includes a plug, a locking rod, a pressing block and a compression spring, and the magnetic cover plate and the instrument housing are both provided with through holes for the plug to be inserted; The outer wall of the insert block is provided with a receiving groove. One end of the locking rod is rotatably connected to the insert block. The pressing block is moved and disposed in the receiving groove and is located on the rotation path of the locking rod. The pressing block abuts against the locking rod. The compression spring is disposed in the receiving groove. The two ends of the compression spring are respectively connected to the pressing block and the insert block. The direction of the spring force of the compression spring is parallel to the direction of movement of the pressing block. The instrument housing has a slot for the locking rod to be engaged, and the slot communicates with the insertion hole. The insertion block is inserted into the insertion hole in one direction. When the locking rod rotates and presses against the pressure block, the pressure block compresses the compression spring, so that the locking rod is in the receiving groove. When the locking rod moves to a position corresponding to the slot, the compression spring drives the pressure block to reset, and the pressure block lifts the locking rod to rotate and engage with the slot. One end of the insert is detachably connected to a screw. The screw is located on the opening and closing path of the magnetic cover plate. The screw and the insert form a T-shape. When the locking rod is located in the locking slot, the screw is in close contact with the top of the magnetic cover plate.

[0029] By adopting the above technical solution, the anti-detachment component further connects the magnetic cover plate and the instrument shell together, improving the stability of the magnetic cover plate and the source chamber body. Even if the source chamber screws become loose and fall off, the presence of the anti-detachment component prevents the source chamber from opening, playing a double insurance role.

[0030] During installation, insert the insert blocks into the magnetic cover plate and instrument housing sequentially from top to bottom. During insertion, the locking rod will rotate under the corresponding force and press against the pressure block. Since the pressure block can only move in a straight line, it presses against the compression spring, causing the spring to elastically deform and be compressed, allowing the locking rod to fall into the receiving groove. The width of the insertion hole is slightly larger than the width of the insert block, so that the insert block can pass smoothly through the insertion hole when the locking rod falls into the receiving groove.

[0031] When the locking lever moves to the position corresponding to the slot, the elastic restoring force of the compression spring drives the pressure block to reset. The movement of the pressure block generates a pushing force on the locking lever, causing it to rotate away from the receiving slot and fall into the slot. At this point, the insert block is installed. Then, the screw is horizontally screwed onto the end of the insert block near the magnetic cover plate. The screw and the insert block are arranged in a T-shape, restricting the insert block from moving further downward.

[0032] In practical applications, when the source chamber screw falls off, the opening and closing direction of the source chamber body changes from the side close to the formation to the side facing away from the formation, meaning the opening direction of the source chamber body is opposite to the insertion direction of the insert block. At this time, although the magnetic cover plate tends to open due to vibration, i.e., the magnetic cover plate exerts an upward force on the screw; because the locking rod falls into the locking slot and can only rotate in the direction close to the receiving slot, the insert block cannot be pulled out in the opposite direction and can only continue to move in the insertion direction, thus the locking rod prevents the insert block from detaching from the insertion hole.

[0033] It should be noted that the insert can only move in one direction and cannot move in the opposite direction. It is through this property that the anti-detachment component can be detached at the same time, and the magnetic cover can be prevented from detaching from the instrument shell.

[0034] Preferably, the insert block has a T-shaped groove, and a T-shaped block is connected to one side of the pressing block, with the T-shaped block engaging in the T-shaped groove.

[0035] By adopting the above technical solution, the T-block and T-slot cooperate with each other to restrict the pressure block to only make linear movements.

[0036] Preferably, it further includes a limiting ring, which is disposed at the rotating end of the clamping rod. The limiting ring has an arc-shaped groove, which is arranged along the rotation direction of the clamping rod. A protruding post is connected to the clamping rod, and the protruding post passes through the arc-shaped groove.

[0037] By adopting the above technical solution, when the lever rotates, the protrusion will rotate synchronously in the arc groove. The rotation direction and amplitude of the lever are limited by the cooperation between the protrusion and the arc groove.

[0038] Preferably, the pressure block is in the shape of a right trapezoid, with the inclined surface of the right trapezoid facing the clamping rod, and the T-shaped block is located at the bottom of the right trapezoid.

[0039] By adopting the above technical solution, since the inclined surface of the pressure block faces the clamping rod, as the clamping rod rotates, the clamping rod can always abut against the pressure block and drive the pressure block to make linear motion.

[0040] In summary, this application includes at least one of the following beneficial technical effects: (1) The opening and closing direction of the source chamber body has changed from the traditional side close to the formation to the direction away from the formation, which significantly reduces the frictional loss between the source chamber body and the well wall during the logging process and effectively avoids damage to the source chamber body structure caused by long-term friction. At the same time, this design can effectively reduce the phenomenon of source chamber screws loosening or falling off due to vibration or friction, fundamentally reducing the risk of the source chamber accidentally opening and piercing the well wall, and greatly improving the safety of logging operations.

[0041] (2) By adding a magnetic cover plate to the main body of the source chamber, even if the source chamber falls into the well, it can be retrieved by strong magnetism. This design not only significantly improves the success rate of retrieval operations, but also greatly shortens the time required for retrieval, thereby effectively reducing the environmental pollution risk and economic loss caused by the radioactive source remaining at the bottom of the well.

[0042] (3) This technology optimizes the source loading structure. Through the synergistic effect of the source chamber screw spring and the matching thread on the magnetic cover, it not only ensures the ease of operation during the source loading process, but also effectively prevents the source chamber screw from accidentally falling off. This improvement not only reduces the difficulty of source loading for operators, but also reduces the radiation exposure time during operation and improves operational safety.

[0043] (4) Through a unique T-slot connection structure and a double fixing design (M8 fastening screws and Φ5 coiled pins), the magnetic cover plate and density source chamber can be detached as a whole under extreme conditions. This failure protection mechanism not only ensures the integrity of the detached parts, but also facilitates subsequent salvage due to its overall magnetic properties, forming a multi-layered safety guarantee system. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the magnetophilic density source chamber structure in Embodiment 1 of this application; Figure 2 yes Figure 1 A schematic cross-section of the medium-density logging tool AA; Figure 3 This is a schematic diagram of the structure of the magnetic cover plate rotating around the source chamber pin in Embodiment 1 of this application; Figure 4 This is a schematic diagram of the magnetophilic density source chamber structure in Embodiment 2 of this application; Figure 5 This is a schematic diagram of the anti-detachment component in Embodiment 2 of this application.

[0045] Reference numerals: 1. Instrument housing; 2. Source chamber pin; 3. Magnetophilic cover plate; 4. Fastening screw; 5. Elastic washer; 6. Coil pin; 7. Source chamber body; 8. Density source; 9. Source chamber screw; 10. Screw spring; 11. X-ray window; 12. Anti-detachment component; 121. Insertion block; 122. Locking rod; 123. Pressure block; 124. Compression spring; 13. Insertion hole; 14. Receiving groove; 15. Locking groove; 16. Screw; 17. Limiting ring; 18. Arc groove; 19. Protruding post. Detailed Implementation

[0046] The technical solutions of this application will now be described with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can be embodied in many different forms and is not limited to the embodiments described herein.

[0047] In the representation of this application, the reference to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., means that a specific feature, structure, material, or characteristic represented in connection with that embodiment or example is included in at least one embodiment or example of this application. Moreover, the specific features, structures, materials, or characteristics represented may be combined in any suitable manner in one or more embodiments or examples.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0049] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection; a detachable connection; an integral part; or a mechanical connection. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0050] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Without conflict, those skilled in the art can combine and integrate the different embodiments or examples shown in this application, as well as the features of those embodiments or examples.

[0051] Example 1 This application discloses a magnetic density source chamber structure design. (Refer to...) Figure 1 and Figure 2 The magnetophilic density source chamber structure includes an instrument housing 1, a source chamber pin 2, a magnetophilic cover plate 3, a fastening screw 4, an elastic washer 5, a coiled pin 6, a source chamber body 7, a density source 8, a source chamber screw 9, a screw spring 10, and a radiation window 11. The instrument housing 1 serves as the mounting carrier. A T-slot is formed on the magnetophilic cover plate 3, within which the source chamber body 7 is installed, and the density source 8 is housed. The source chamber body 7 is fixed to the magnetophilic cover plate 3 by the fastening screw 4 and the coiled pin 6. The elastic washer 5 is fitted onto the fastening screw 4, which is coated with thread-locking adhesive. The fastening screw 4 passes through the magnetophilic cover plate 3 and is threaded onto the source chamber body 7. The elastic washer 5 compensates for assembly gaps in the connecting components and buffers vibration and impact through its own elastic deformation, effectively preventing the screw from loosening due to long-term stress or vibration. The thread-locking adhesive applied to the fastening screw 4, after curing, fills the thread gaps, enhances the locking force between the threads, and also serves as a seal to prevent leakage and corrosion. The coiled pin 6 is located on one side of the fastening screw 4 and is used to further connect the magnetic cover plate 3 and the instrument housing 1, so that the source chamber body 7 and the magnetic cover plate 3 are connected as one unit, improving the stability of the magnetic cover plate 3 and playing a double insurance role. In this embodiment, two fastening screws 4 are provided, and the diameter of the coiled pin 6 is 5mm.

[0052] Specifically, the magnetic cover plate 3 is made of a high-saturation magnetic permeability alloy with a magnetization intensity ≥80 emu / g and a thickness of 8-12mm, giving it high magnetization intensity and enabling rapid response and strong magnetic adsorption. The upper side of the magnetic cover plate 3 is rotatably connected to the instrument housing 1 via a source chamber pin 2, allowing it to rotate around the source chamber pin 2. The lower side of the magnetic cover plate 3 is mounted on the instrument housing 1 via source chamber screws 9, which pass through the magnetic cover plate 3 and are threaded onto the instrument housing 1. Two source chamber screws 9 are provided. Each source chamber screw 9 is also fitted with a screw spring 10. The screw spring 10 compensates for minor gaps during assembly by utilizing its elastic deformation, buffering vibrations and impacts generated during the use of the magnetic cover plate 3, while continuously providing stable preload. This effectively prevents the source chamber screws 9 from loosening due to long-term stress fluctuations or vibrations, ensuring the connection stability between the magnetic cover plate 3 and the instrument housing 1 and extending the overall structural reliability.

[0053] When loading the source, loosen the source chamber screw 9 with the hexagonal end of the universal source gun, hook the source gun lifting hook onto the lifting hole on the magnetic cover plate 3, and open the source chamber; at this time, the source chamber screw 9 will spring up under the elastic action of the spring, which can make room for loading the universal source gun, making it convenient to load the source; and since the magnetic cover plate 3 has the same kind of thread as the source chamber screw 9, it can prevent the source chamber screw 9 from falling off after it springs up, preventing the source chamber screw 9 from falling off or being lost due to operator negligence or error. At the same time, it can reduce the operator's source loading time, reduce the difficulty of operation, and reduce the irradiation time.

[0054] The X-ray window 11 is fixedly mounted on the instrument housing 1 by a rolled pin. The X-ray window 11 is located below the source chamber body 7, and the direction in which the X-rays emitted from the X-ray window 11 are close to the formation. The opening direction of the source chamber body 7 is opposite to the formation. In this embodiment, the connection strength between the source chamber body 7 and the magnetic cover plate 3 is greater than the strength of the source chamber pin 2.

[0055] Combination Figure 3 In some application scenarios, even if the source chamber screw 9 is not tightened due to operational errors or loosened due to vibration, causing the source chamber cover to open, the magnetic cover plate 3 (end A) will pierce the well wall. At this time, the magnetic cover plate 3 and the source chamber body 7 will rotate counterclockwise around the source chamber pin 2. During this process, the source chamber body 7 will rotate together with the magnetic cover plate 3 (end B) through the T-slot of the magnetic cover plate 3. The two M8 fastening screws 4 only serve a connecting function and are not subjected to shear force, preventing the source chamber body 7 from separating from the magnetic cover plate 3 due to shearing failure of the fastening screws 4, which would increase the difficulty of retrieval. The coiled pin 6 has the same function as the two M8 fastening screws 4 in this process, providing double protection.

[0056] Because the connection strength between the source chamber body 7 and the magnetically attached cover plate 3 is greater than the strength of the source chamber pin 2, the source chamber pin 2 is cut off first, causing the magnetically attached cover plate 3 to detach together with the source chamber body 7. This overall magnetic connection allows for retrieval using strong magnetic force, reducing the difficulty of retrieval. This design not only significantly improves the success rate of retrieval operations but also greatly shortens the time required for retrieval, thereby effectively reducing the environmental pollution risks and economic losses caused by the radioactive source remaining at the bottom of the well.

[0057] The implementation principle of the magnetic density source chamber structure design in this application embodiment is as follows: During the logging process of the density logging tool, the direction of the radiation emission needs to be close to the formation. The connection between the radiation window 11 and the instrument housing 1 ensures that the radiation can penetrate the formation normally. Compared with previous density logging tools, the opening and closing direction of the source chamber body 7 has changed from being close to the formation to facing away from the formation. This can effectively reduce the wear of the source chamber body 7 caused by friction and the accident of the source chamber body 7 piercing the well wall due to the loosening and falling off of the source chamber screw 9. At the same time, the addition of the magnetic cover plate 3 on the source chamber body 7 means that even if the source chamber falls into the well, it can be retrieved by strong magnetism, reducing the difficulty of retrieval, reducing retrieval time, and reducing economic losses.

[0058] Example 2 Based on the above embodiments, such as Figure 4 and Figure 5 As shown, the difference between Embodiment 2 and Embodiment 1 is that Embodiment 2 further includes an anti-detachment component 12, which is further connected to the magnetic cover plate 3 and the instrument housing 1, and is used to prevent the magnetic cover plate 3 from detaching from the instrument housing 1.

[0059] The anti-detachment component 12 includes an insertion block 121, a locking rod 122, a pressure block 123, and a compression spring 124. A through-hole 13 is provided through both the magnetic cover plate 3 and the instrument housing 1, for inserting the insertion block 121. The width of the through-hole 13 is slightly larger than the width of the insertion block 121. A receiving groove 14 is provided on the outer wall of the insertion block 121. One end of the locking rod 122 is rotatably connected to the insertion block 121. The pressure block 123 moves within the receiving groove 14 and is located on the rotation path of the locking rod 122, abutting against the locking rod 122. The compression spring 124 is installed within the receiving groove 14, with both ends connected to the pressure block 123 and the insertion block 121 respectively. The direction of the spring force of the compression spring 124 is parallel to the direction of movement of the pressure block 123, which moves along the width direction of the insertion block 121.

[0060] The instrument housing 1 has a slot 15 for the locking rod 122 to be engaged, and the slot 15 communicates with the insertion hole 13; the insertion block 121 is inserted into the insertion hole 13 in one direction. When the locking rod 122 rotates and presses against the pressure block 123, the pressure block 123 exerts a compressive force on the compression spring 124, causing the locking rod 122 to be positioned within the receiving groove 14. When the locking rod 122 moves to a position corresponding to the slot 15, the compression spring 124 drives the pressure block 123 to reset, and the pressure block 123 lifts the locking rod 122 to rotate and engage it within the slot 15. One end of the insert block 121 is detachably connected to a screw 16. The screw 16 is located on the opening and closing path of the magnetic cover plate 3. The screw 16 and the insert block 121 are arranged in a T-shape. When the locking rod 122 is located in the locking groove 15, the screw 16 is in close contact with the top of the magnetic cover plate 3, and the force of the magnetic cover plate 3 is transmitted to the insert block 121 through the screw 16. In this embodiment, the pressure block 123 is in the shape of a right trapezoid, with the inclined surface of the right trapezoid facing the locking rod 122. A T-shaped block is fixedly connected to the bottom of the right trapezoid. A T-shaped groove is opened on the insert block 121, which communicates with the receiving groove 14. The T-shaped block is engaged in the T-shaped groove. The T-shaped block and the T-shaped groove cooperate with each other, restricting the pressure block 123 to only be able to move in a straight line.

[0061] A limiting ring 17 is also installed at one end of the locking rod 122 that rotates around the insert block 121. The limiting ring 17 has an arc-shaped groove 18, which is set along the rotation direction of the locking rod 122. A protruding post 19 is fixedly connected to the locking rod 122. The protruding post 19 passes through the arc-shaped groove 18. When the locking rod 122 rotates, the protruding post 19 moves within the arc-shaped groove 18. The rotation direction and amplitude of the locking rod 122 are limited by the cooperation between the protruding post 19 and the arc-shaped groove 18.

[0062] During installation, insert block 121 is inserted into the magnetic cover plate 3 and the instrument housing 1 from top to bottom. During insertion, the locking rod 122 rotates under the corresponding force and presses against the pressure block 123. Since the pressure block 123 can only move in a straight line, it presses against the compression spring 124. The compression spring 124 undergoes elastic deformation and is compressed, causing the locking rod 122 to fall into the receiving groove 14. The width of the insertion hole 13 is slightly larger than the width of the insert block 121, so that the insert block 121 can pass smoothly through the insertion hole 13 when the locking rod 122 falls into the receiving groove 14.

[0063] When the locking lever 122 moves to the position corresponding to the slot 15, under the elastic restoring force of the compression spring 124, the compression spring 124 drives the pressure block 123 to reset. The movement of the pressure block 123 can generate a pushing force on the locking lever 122, causing the locking lever 122 to rotate away from the receiving groove 14 and fall into the slot 15. At this time, the insert block 121 is installed. Then, the screw 16 is horizontally screwed to the end of the insert block 121 near the magnetic cover plate 3. The screw 16 and the insert block 121 are arranged in a T-shape, which restricts the insert block 121 from moving further down.

[0064] In practical applications, when the source chamber screw 9 falls off, the opening direction of the source chamber body 7 changes from the side close to the formation to the side facing away from the formation, meaning the opening direction of the source chamber body 7 is opposite to the insertion direction of the insert block 121. At this time, although the magnetic cover plate 3 is subjected to vibration and tends to open, i.e., the magnetic cover plate 3 exerts an upward force on the screw 16; since the locking rod 122 falls into the locking groove 15, and the locking rod 122 can only rotate in the direction close to the receiving groove 14, the insert block 121 cannot be pulled out in the opposite direction, and can only continue to move in the insertion direction, thus the locking rod 122 restricts the insert block 121 from disengaging from the insertion hole 13.

[0065] It should be noted that the insert 121 can only move in one direction and cannot move in the opposite direction. It is through this property that the anti-detachment component 12 can be detached at the same time as the magnetic cover 3 can be prevented from detaching from the instrument housing 1.

[0066] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A design of a magnetic density source cartridge structure, characterized by, The application relates to a radioactive source chamber, which comprises an instrument shell (1), a source chamber pin (2), a magnetically attractive cover plate (3), a fastening screw (4), a source chamber main body (7), a density source (8), a source bin screw (9) and a radiation window (11), a T-shaped slot is formed in the magnetically attractive cover plate (3), the source chamber main body (7) is arranged in the T-shaped slot, the source chamber main body (7) is fixed to the magnetically attractive cover plate (3) through the fastening screw (4), and the density source (8) is arranged in the source chamber main body (7); the upper side of the magnetically attractive cover plate (3) is rotatably connected to the instrument shell (1) through the source chamber pin (2), the lower side of the magnetically attractive cover plate (3) is arranged on the instrument shell (1) through the source bin screw (9); the radiation window (11) is arranged on the instrument shell (1) through a rolling shaft pin, the radiation window (11) is located below the source chamber main body (7), the direction in which the radiation window (11) emits radiation is close to the stratum, and the opening direction of the source chamber main body (7) faces away from the stratum.

2. The design of a magnetic density source bin structure according to claim 1, wherein, The application further comprises an elastic washer (5), the elastic washer (5) is sleeved on the fastening screw (4), and the fastening screw (4) is coated with thread glue.

3. The design of a magnetic density source bin structure according to claim 1, wherein, The application further comprises a rolling pin (6), the rolling pin (6) is located on one side of the fastening screw (4) and is used for connecting the magnetically attractive cover plate (3) and the instrument shell (1), and the diameter of the rolling pin (6) is 5 mm.

4. The design of a magnetic density source bin structure according to claim 1, wherein, The application further comprises a screw spring (10), the screw spring (10) is sleeved on the source bin screw (9).

5. The design of a magnetic density source bin structure according to claim 1, wherein, The connecting strength of the source chamber main body (7) and the magnetically attractive cover plate (3) is greater than the strength of the source chamber pin (2).

6. The design of a magnetic density source bin structure according to claim 1, wherein, The magnetically attractive cover plate (3) is made of high-saturation permeability alloy, the magnetization intensity is greater than or equal to 80 emu / g, and the thickness is 8-12 mm.

7. The design of a magnetic density source structure according to claim 1, wherein, The application further comprises an anti-disengagement assembly (12), the anti-disengagement assembly (12) connects the magnetically attractive cover plate (3) and the instrument shell (1) and is used for limiting the magnetically attractive cover plate (3) from disengaging from the instrument shell (1); the anti-disengagement assembly (12) comprises an insertion block (121), a clamping rod (122), a pressing block (123) and a compression spring (124), the magnetically attractive cover plate (3) and the instrument shell (1) are both provided with an insertion hole (13), and the insertion hole (13) is used for inserting the insertion block (121); An accommodating groove (14) is formed in the outer side wall of the insertion block (121), one end of the clamping rod (122) is rotatably connected to the insertion block (121), the pressing block (123) is movably arranged in the accommodating groove (14) and located on the rotating path of the clamping rod (122), and the pressing block (123) abuts against the clamping rod (122); the compression spring (124) is arranged in the accommodating groove (14), the two ends of the compression spring (124) are connected with the pressing block (123) and the insertion block (121) respectively, and the elastic force direction of the compression spring (124) is parallel to the moving direction of the pressing block (123). The instrument shell (1) is provided with a clamping groove (15) for clamping the clamping rod (122), and the clamping groove (15) is communicated with the insertion hole (13); the insertion block (121) is inserted into the insertion hole (13) in one direction, when the clamping rod (122) is rotated and pressed on the pressing block (123), the pressing block (123) extrudes the compression spring (124), so that the clamping rod (122) is located in the containing groove (14); when the clamping rod (122) moves to a position corresponding to the clamping groove (15), the compression spring (124) drives the pressing block (123) to reset, and the pressing block (123) lifts the clamping rod (122) to rotate and clamp into the clamping groove (15); One end of the insertion block (121) is detachably connected with a screw rod (16), the screw rod (16) is located on the opening and closing path of the magnetic cover plate (3), and the screw rod (16) and the insertion block (121) are in T shape; when the clamping rod (122) is located in the clamping groove (15), the screw rod (16) is in contact with the upper side of the magnetic cover plate (3).

8. The design of a magnetic density source bin structure according to claim 7, wherein, The insertion block (121) is provided with a T-shaped groove, and one side of the pressing block (123) is connected with a T-shaped block, and the T-shaped block is clamped in the T-shaped groove.

9. The design of a magnetic density source structure according to claim 7, wherein, Further comprising a limiting ring (17), the limiting ring (17) is arranged at the rotating end of the clamping rod (122), the limiting ring (17) is provided with an arc-shaped groove (18), the arc-shaped groove (18) is arranged along the rotating direction of the clamping rod (122), and the clamping rod (122) is connected with a convex column (19), and the convex column (19) penetrates through the arc-shaped groove (18).

10. The design of a magnetic density source bin structure according to claim 8, wherein, The pressing block (123) is in the shape of a right-angled trapezoid, the inclined surface of the right-angled trapezoid faces the clamping rod (122), and the T-shaped block is arranged at the lower base of the right-angled trapezoid.

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