Acoustic variable density logging tool

Abstract

This invention relates to the field of logging equipment technology, and in particular provides an acoustic variable density logging tool, comprising an upper casing and a lower casing fixedly connected to the upper casing. Both the upper and lower casings have heat insulation layers fitted and fixed to their inner walls. The lower casing contains a carrier plate, a temperature sensor, and a pressure sensing head. A processor is fixed to the carrier plate. A through hole is provided at the bottom of the lower casing, and a corrugated sleeve is fixedly installed within the through hole. A first sealing element is provided inside the corrugated sleeve. The outer walls of the sensing ends of the temperature sensor and the pressure sensing head are tightly sealed to the first sealing element. When abnormal excessive slippage occurs, an alarm signal is promptly issued, allowing operators to promptly monitor the equipment's operating status, avoid equipment malfunctions and downhole accidents, and ensure that the logging tool meets the requirements for safe logging operations in deep wells.

Description

Technical Field

[0001] This invention relates to the field of well logging equipment technology, and in particular to an acoustic variable density well logging instrument. Background Technology

[0002] Sonic variable density logging tools are indispensable downhole monitoring equipment in oil and gas exploration and development. Their core function is to collect downhole temperature and pressure parameters in real time through temperature sensors and pressure sensors, process the data, and then feed it back to surface equipment, providing crucial data support for formation evaluation and well condition analysis. Due to the complex downhole environment, including high pressure, high humidity, and mud erosion, the logging tool's sealing performance, shock absorption performance, and operational stability directly determine the accuracy of the monitoring data and the equipment's lifespan.

[0003] Existing logging tools use only a single sealing ring between the sensor head and the housing through-hole for sealing, without any elastic buffer components. The sensor head is fixedly connected to the housing, making it unable to withstand high-pressure impacts downhole. Furthermore, the sealing ring is prone to loosening due to vibration and impact, leading to well fluid seepage. At the same time, the sensor head lacks any elastic buffering and linkage sealing structure, as well as early warning and protection functions. The high-pressure impact force downhole acts directly on the fixed sensor head, easily causing damage to the sensor head. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an acoustic variable density logging tool, comprising an upper casing and a lower casing fixedly connected to the upper casing. A bottom cover is threadedly connected to the bottom of the lower casing. Heat insulation layers are fitted and fixed to the inner walls of both the upper and lower casings. The lower casing contains a carrier plate, a temperature sensor, and a pressure sensing head. A processor is fixed to the carrier plate. A through hole is provided at the bottom end of the bottom cover, and a corrugated sleeve is fixedly installed within the through hole. A first sealing element is provided inside the corrugated sleeve. The outer walls of the sensing ends of the temperature sensor and the pressure sensing head are tightly sealed to the first sealing element, and the sensing ends of both the temperature sensor and the pressure sensing head pass through the first sealing element and are exposed outside the lower casing. A preload spring is provided inside the lower casing above the pressure sensing head and temperature sensor. The system comprises an elastic ring and a sealing slide. The outer ring of the sealing slide has a piston plate, the outer edge of which slides against the inner wall of the lower housing. A preload spring is vertically positioned inside the lower housing, its top end connected to the bottom surface of the sealing slide, and its bottom end connected to the top of the pressure sensor and temperature sensor. The elastic ring is vertically positioned inside the lower housing, its top end connected to the bottom surface of the carrier plate, and its bottom end connected to the top surface of the sealing slide. The sealing slide, preload spring, elastic ring, corrugated sleeve, and first seal together constitute a sealing buffer linkage structure, used to maintain a sealed fit between the pressure sensor and temperature sensor during sliding buffering. An internal tube is fixed to the bottom surface of the carrier plate, and an external tube is slidably fitted around the internal tube. A travel alarm is located on the bottom surface of the carrier plate corresponding to the top of the external tube. An alarm is located inside the upper housing, and the alarm is electrically connected to the travel alarm.

[0005] Preferably, the preload spring is in elastic compression in its natural state. Its elastic force pushes the pressure sensing head and temperature sensor to extend outward along the first seal inside the corrugated sleeve. Under the elastic push of the elastic ring on the sealing slide, the outer edge of the sealing slide always maintains a sealing sliding fit with the inner wall of the lower sleeve.

[0006] Preferably, the bottom of the lower casing is threadedly connected to a bottom cover, and the top of the upper casing is threadedly connected to a top cover, with a lifting ring fixedly provided on the top of the top cover.

[0007] Preferably, the heat insulation layer is annular, with an annular sealing ring fixed to its inner wall, and the outer edge of the piston plate slides in conjunction with the inner wall of the annular sealing ring.

[0008] Preferably, the top ends of the temperature sensor and the pressure sensing head are jointly fixed with a connecting plate, and the bottom end of the preload spring is connected to the top surface of the connecting plate.

[0009] Preferably, the processor is fixed to the top surface of the carrier plate, and a vertically downward-facing inner tube is fixed to the center of the bottom surface of the carrier plate. An outer tube is slidably fitted onto the outside of the inner tube. A third sealing element is provided between the inner wall of the outer tube and the sliding surface of the outer wall of the inner tube. The bottom end of the outer tube passes through the sealing slide and enters the preload spring, which is fixedly connected to the top surface of the connecting plate. A wire hole is provided on the carrier plate and the connecting plate. The upper and lower ends of the wire hole are respectively connected to the cavities of the inner tube and the outer tube. The travel alarm is set at the top of the outer tube, and the alarm is electrically connected to the travel alarm.

[0010] Preferably, the piston plate is a rubber plate with a second sealing element on its outer edge. The second sealing element slides in conjunction with the inner wall of the lower sleeve. The second sealing element, the third sealing element, and the first sealing element are all O-rings.

[0011] Preferably, the elastic ring is made of rubber and has a spiral structure. Its bottom end is fitted and connected to the outer edge of the sealing slide, and its top end is fitted and connected to the outer edge of the carrier plate. The preload spring is a cylindrical helical spring, and its top end is connected to the center of the sealing slide. The axis of the preload spring is coaxial with the axis of the elastic ring and also with the axis of the lower sleeve.

[0012] The advantages of this invention compared to the prior art are:

[0013] This invention, an acoustic variable density logging tool, effectively solves the shortcomings of existing logging tools in harsh downhole environments, such as easy damage to the sensing head, poor sealing, easy seepage of well fluid, and lack of early warning protection, through the rational assembly and synergistic effect of its components. The sealed sliding linkage structure, composed of a sealed sliding mechanism and a buffer sliding mechanism, solves the problems of directly exposed sensing heads and lack of linkage sealing and buffering in existing tools. The corrugated sleeve and the first sealing element achieve basic sealing of the sensing end, while the sealing slide, pre-compression spring, and elastic ring work together to achieve dynamic sealing during the sliding process, effectively preventing downhole fluid and mud from seeping into the gap between the penetration hole and the sensing head, protecting the core components such as the processor and sensors inside the equipment from damage. The buffer sliding mechanism, under the buffering elasticity of the elastic ring, can buffer the direct impact of high-pressure downhole forces on the pressure sensing head and temperature sensor, avoiding deformation and damage to the sensing head, ensuring the accuracy of detection parameters, and extending the service life of the equipment. Furthermore, it features an electrical connection function for travel alarm and alarm device, which makes up for the lack of early warning and protection functions in existing logging instruments. It can monitor the sliding travel of the sensing head in real time and issue an alarm signal in time when abnormal excessive sliding occurs. This allows operators to keep abreast of the equipment's operating status, avoid equipment failure and downhole accidents, and ensure that the logging instrument meets the requirements of safe logging operations in deep wells. Attached Figure Description

[0014] Figure 1A schematic plan view of the lower casing of the acoustic variable density logging tool provided in an embodiment of the present invention after it has been cut open. Figure 2 The acoustic variable density logging tool provided for the embodiments of the present invention is composed of Figure 1 A bottom-view diagram taken from the bottom of the cover. Figure 3 A top view of the sealed slide in the acoustic variable density logging tool provided in an embodiment of the present invention; Figure 4 A top view of the carrier plate only in the acoustic variable density logging tool provided for an embodiment of the present invention; Figure 5 A schematic diagram of the sliding sleeve principle after only the inner and outer tubes of the acoustic variable density logging tool provided in the embodiment of the present invention are cut open; Figure 6 This is a schematic diagram of the main view of the acoustic variable density logging tool provided in the embodiment of the present invention after only the sealed slide is cut open.

[0015] In the diagram: 1. Upper housing; 2. Lower housing; 3. Bottom cover; 4. Top cover; 5. Lifting ring; 6. Insulation layer; 7. Carrier plate; 8. Temperature sensor; 9. Pressure sensor head; 10. Processor; 11. Through hole; 12. Corrugated sleeve; 13. First seal; 14. Preload spring; 15. Elastic ring; 16. Sealing slide; 17. Inner tube; 18. Outer tube; 19. Annular sealing ring; 20. Piston plate; 21. Second seal; 22. Third seal; 23. Connecting plate. Detailed Implementation

[0016] The above and other embodiments and advantages 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.

[0017] In one implementation, such as Figures 1-6 As shown: This embodiment provides an acoustic variable density logging tool, including an upper casing 1 and a lower casing 2 fixedly connected to the upper casing 1. A bottom cover 3 is connected to the bottom of the lower casing 2, and a top cover 4 is threadedly connected to the top of the upper casing 1. A lifting ring 5 is fixedly provided on the top of the top cover 4, which facilitates connection with external lifting equipment. The bottom cover 3 and the top cover 4 seal the upper and lower ends of the tool. A heat insulation layer 6 is attached and fixed to the inner walls of both the upper casing 1 and the lower casing 2. A carrier plate 7, a temperature sensor 8, and a pressure sensor are provided inside the lower casing 2. The processor 10 is fixed on the carrier plate 7 and the head 9. A through hole 11 is provided at the bottom end of the bottom cover 3, and a corrugated sleeve 12 is fixed inside the through hole 11. A first sealing element 13 is provided inside the corrugated sleeve 12. The outer wall of the sensing end of the temperature sensor 8 and the outer wall of the sensing end of the pressure sensor head 9 are both tightly sealed with the first sealing element 13, and the sensing ends of the temperature sensor 8 and the pressure sensor head 9 both pass through the first sealing element 13 and are exposed outside the lower housing 2. The lower housing 2 contains a corresponding pressure sensor. A preload spring 14 and an elastic ring 15 are provided above the pressure sensor 9 and the temperature sensor 8. A piston plate 20 is provided on the outer ring of the sealing slide 16. The outer edge of the piston plate 20 slides in contact with the inner wall of the lower housing 2. The preload spring 14 is vertically installed inside the lower housing 2. Its top end is connected to the bottom surface of the sealing slide 16, and its bottom end is connected to the top end of the pressure sensor 9 and the temperature sensor 8. The elastic ring 15 is vertically installed inside the lower housing 2. Its top end is connected to the bottom surface of the carrier plate 7, and its bottom end is connected to the top surface of the sealing slide 16. The sealing slide 16, the preload spring 14, the elastic ring 15, the corrugated sleeve 12, and the first seal 13 together constitute a sealing buffer linkage structure, which is used to keep the pressure sensor 9 and the temperature sensor 8 sealed in contact during the sliding buffer process. An inner tube 17 is fixed on the bottom surface of the carrier plate 7. An outer tube 18 is slidably fitted on the outside of the inner tube 17. A stroke alarm is provided on the bottom surface of the carrier plate 7 corresponding to the top of the outer tube 18. An alarm is provided inside the upper housing 1. The alarm is electrically connected to the stroke alarm.

[0018] This implementation method illustrates the working principle: After the acoustic variable density logging tool is run into the well, under normal downhole conditions (no extreme high pressure, no drastic pressure fluctuations), its working process is consistent with the prior art: the sensing ends of the temperature sensor 8 and the pressure sensing head 9 are exposed outside the lower casing 2, directly contacting the downhole environment, and capturing downhole temperature and pressure parameters in real time. The captured parameters are transmitted to the processor 10 on the inner carrier plate 7 of the lower casing 2 through a preset line. The processor 10 processes and analyzes the data and then feeds it back to the surface control equipment, providing basic data support for formation evaluation and well condition analysis.

[0019] When high pressure (or high-pressure gas) occurs underground, the high pressure will directly act on the exposed temperature sensor 8 and pressure sensing head 9, pushing the sensing head to slide axially upward. At this time, the preload spring 14 connected to the top of the sensing head will be compressed, and at the same time, a reverse buffering force will be generated, which will play a preliminary buffering role on the sliding of the sensing head, slowing down the upward sliding speed of the sensing head and preventing the high pressure impact force from being directly transmitted to the inside of the equipment. At the same time, the elastic ring 15 (rubber material, spiral structure) will be squeezed by the sealing slide 16 and undergo elastic deformation. During the deformation process, a reverse elastic thrust will be generated, which, together with the tension of the preload spring 14, will form a bidirectional support for the sealing slide 16, keeping the sealing slide 16 stable and buffering the mechanical impact, thereby achieving buffer protection for both sensors.

[0020] The piston plate 20 on the outer ring of the sealing slide 16 slides upward along the inner wall of the lower housing 2 in sync with the sliding of the sensing head. The second sealing element 21 on the outer edge of the piston plate 20 is always tightly fitted with the inner wall of the lower housing 2 and will not have gaps due to sliding, forming the first sealing barrier from the inside side of the equipment. At the same time, the corrugated sleeve 12 in the through hole 11 at the bottom of the lower housing 2 will adapt to the sliding of the sensing head to meet the stroke of the two sensors. The first sealing element 13 inside them is always tightly fitted to the outer wall of the sensing head of the two sensors, and will not loosen, leak air or seep liquid due to the sliding of the sensing head, forming the second sealing barrier from the connection between the sensing end and the through hole 11.

[0021] The aforementioned sealing barriers work together seamlessly, which is the core reason for ensuring that well fluid does not seep in: the first seal (piston plate 20 and inner wall of lower casing 2) prevents gas from seeping in through the gap between the inner wall of lower casing 2 and sealing slide 16; the second seal (first sealing element 13 and outer wall of sensing head, corrugated sleeve 12) prevents well fluid or high-pressure gas from seeping in through the gap between the through hole 11 and sensing head, and the expansion and contraction characteristics of corrugated sleeve 12 can also prevent the sealing element from being pulled and damaged due to the sliding of sensing head, further improving the reliability of the seal.

[0022] Simultaneously, the coordinated action of the preload spring 14, elastic ring 15, and sealing slide 16 achieves buffering self-protection of the sensing head: the buffering of the preload spring 14 and the deformation buffering of the elastic ring 15 work together to decompose and absorb the high-pressure impact force downhole, preventing the sensing head from deforming or being damaged due to excessive instantaneous force; during the synchronous sliding of the sealing slide 16, it always maintains a sliding fit with the inner wall of the lower casing 2 through the piston plate 20, ensuring the smoothness of the buffering action and preventing sealing failure during the buffering process through the sealing fit, thus achieving simultaneous buffering protection and sealing to prevent leakage. In addition, when the sliding stroke of the sensing head reaches the preset value, the external pipe 18 will slide synchronously with the sensing head to contact the stroke alarm, triggering the stroke alarm, which in turn activates the alarm in the upper casing 1 to issue a warning, reminding the operator to deal with it in time, avoiding damage to the sealing structure and well fluid seepage caused by excessive sliding of the sensing head, and ensuring that the detection is carried out within a reasonable range or in a safe environment.

[0023] This embodiment effectively combines sealed sliding and buffered sliding: the sealed sliding linkage structure solves the problem of the existing sensor head being directly exposed and lacking linkage sealing and buffering. The corrugated sleeve 12 and the first sealing element 13 achieve basic sealing of the sensing end, while the sealing slide 16, the pre-compression spring 14, and the elastic ring 15 cooperate to achieve dynamic sealing during the sliding process, effectively preventing downhole fluid and mud from seeping into the gap between the through hole 11 and the sensor head, protecting the core components such as the processor 10 and sensors inside the equipment from damage. The buffered sliding, under the buffering elasticity of the elastic ring 15, can buffer the direct impact of the downhole high pressure on the pressure sensor head 9 and temperature sensor 8, avoiding deformation and damage to the sensor head, ensuring the accuracy of the detection parameters, and extending the service life of the equipment. Moreover, it has a stroke alarm and an electrical connection function with the alarm, making up for the deficiency of existing logging instruments without early warning protection functions. It can monitor the sliding stroke of the sensor head in real time, and issue an alarm signal in time when abnormal excessive sliding occurs, so that operators can keep abreast of the equipment's operating status, avoid equipment failure and downhole accidents, and ensure that the logging instrument meets the requirements of safe logging operations in deep wells.

[0024] In another embodiment, the preload spring 14 is in elastic compression in its natural state (normal state). Its elastic force pushes the pressure sensing head 9 and the temperature sensor 8 to extend outward along the first seal 13 inside the corrugated sleeve 12. Under the elastic push of the elastic ring 15 on the sealing slide 16, the outer edge of the sealing slide 16 drives the second seal 21 to always maintain a sealing sliding fit with the inner wall of the lower sleeve 2.

[0025] In this embodiment, the preload spring 14 is in an elastic compression state under natural conditions. The elastic force generated by the spring itself will continuously act on the pressure sensing head 9 and the temperature sensor 8, pushing them to always maintain an outward extension along the first seal 13 inside the corrugated sleeve 12, ensuring stable contact between the sensing end and the downhole environment, and ensuring the continuity and accuracy of data acquisition.

[0026] When high pressure occurs underground, it acts directly on the exposed sensing end. When the high pressure exceeds the thrust of the preload spring 14 and the elastic ring 15, it will push the pressure sensing head 9 and the temperature sensor 8 to slide axially upwards. At this time, the preload spring 14, which was originally in a stretched state, is compressed, and the resulting reverse elastic force will form resistance, which will initially buffer the sliding of the sensing head and effectively slow down the upward sliding speed of the sensing head, forming initial protection. At the same time, the elastic ring 15 will generate a continuous elastic pushing force on the sealing slide 16. Under the action of this pushing force, the sealing slide 16 always maintains a downward force tendency, and its outer ring second seal 21 will be tightly attached to the inner wall of the lower casing 2. Even if the sealing slide 16 slides upwards synchronously with the sensing head, the second seal 21 will not have any gap with the inner wall of the lower casing 2, and will always maintain a stable sealing sliding fit, laying the foundation for sealing and preventing leakage. In addition, the preload spring 14 provides a reverse thrust to the two sensors, ensuring that the outer walls of their sensing heads are always tightly fitted to the first seal 13 inside the corrugated sleeve 12. Even if the sensing heads slide axially, the fit between the two will not decrease, forming a first sealing barrier at the connection between the sensing end and the through hole 11, directly preventing well fluid from seeping in from the gap. Therefore, the function of the preload spring 14 is not only to buffer, but also to help with sealing. Moreover, the elastic ring 15 provides an elastic pushing force to the sealing slide 16, ensuring that the second seal 21 on the outer ring of the sealing slide 16 is always tightly fitted to the inner wall of the lower sleeve 2, forming a second sealing barrier to prevent gas from seeping in from the gap between the inner wall of the lower sleeve 2 and the sealing slide 16. Thirdly, the seal between the inner wall of the sealing slide 16 and the outer wall of the sensing head will slide synchronously with the two to maintain a tight fit, forming a third sealing barrier to further strengthen the sealing effect. The three sealing barriers are seamlessly connected and work together to completely block all possible paths for well fluid infiltration. At the same time, the corrugated sleeve 12 can adapt to the sliding of the sensing head, preventing the first seal 13 from being damaged by the sliding of the sensing head. This stroke threshold is matched and adapted to the maximum tensile amount of the corrugated sleeve 12.

[0027] In another embodiment, the heat insulation layer 6 is annular, and an annular sealing ring 19 is fixed on its inner wall. The outer edge of the piston plate 20 slides with the inner wall of the annular sealing ring 19. The heat insulation layer 6 plays a role in heat insulation to avoid interference from high temperature downhole. The annular sealing ring 19 provides sliding guidance for the outer edge of the piston plate 20, so that the piston plate 20 can rise and fall smoothly.

[0028] In another embodiment, the top ends of the temperature sensor 8 and the pressure sensing head 9 are jointly fixed to a connecting plate 23, and the bottom end of the preload spring 14 is connected to the top surface of the connecting plate 23. The connecting plate 23 serves as a carrier for mounting the top ends of the two sensors. The bottom end of the preload spring 14 is connected to the top surface of the connecting plate, rather than directly to the top ends of the two sensors, making the structure more reasonable. It also ensures that the two sensors rise and fall synchronously, avoiding offset or misalignment caused by uneven force on the two sensors, thereby preventing the sealing structure from loosening and ensuring the reliability of the seal and the stability of data acquisition.

[0029] In another embodiment, the processor 10 is fixed to the top surface of the carrier plate 7, and a vertically downward inner tube 17 is fixed to the middle of the bottom surface of the carrier plate 7. An outer tube 18 is slidably sleeved on the outside of the inner tube 17. A third seal 22 is provided between the inner wall of the outer tube 18 and the sliding surface of the outer wall of the inner tube 17. The bottom end of the outer tube 18 passes through the sealing slide 16 and enters the preload spring 14 and is fixedly connected to the top surface of the connecting plate. The carrier plate 7 and the connecting plate are provided with wire holes. The upper and lower ends of the wire holes are respectively connected to the cavities of the inner tube 17 and the outer tube 18. The travel alarm is set at the top of the outer tube 18, and the alarm is electrically connected to the travel alarm.

[0030] The processor 10 is fixed to the top surface of the carrier plate 7, away from the high pressure downhole, protecting the core processing components. The inner tube 17 and outer tube 18 are slidably fitted together on the bottom surface of the carrier plate 7. The bottom end of the outer tube 18 passes through the sealing slide 16 and is fixedly connected to the top surface of the connecting plate. The outer tube 18 can move synchronously up and down along the inner tube 17 with the connecting plate, improving stability. A third seal between the sliding surfaces of the outer tube 18 and the inner tube 17 seals the gap between them, preventing gas from seeping into the well. The inner and outer tubes essentially form a liner inside the preload spring 14, preventing the preload spring 14 from bending. The wire holes on the carrier plate 7 and the connecting plate communicate with the cavities of the inner tube 17 and the outer tube 18, forming a closed circuit channel to protect data transmission and early warning connection lines. The processor 10 and the transmission... The wiring between the sensors is laid in two cavities. The upper and lower ends of the wiring harness extend from the upper and lower wire holes and are connected to the processor 10 and the sensor, respectively. The internal wiring method ensures that the sensor's lifting and lowering movement does not affect the sliding connection of the inner and outer tubes. The stroke alarm is set at the top of the outer tube 18 and is electrically connected to the alarm in the upper casing 1. It is used to monitor the sliding stroke of the sensor. For example, when the outer tube 18 rises to the maximum set stroke, its top touches the stroke switch (the stroke switch is fixed on the bottom surface of the carrier plate 7 and corresponds to the stroke position of the top of the outer tube 18). The stroke switch connects to the alarm. The alarm is set inside the upper casing and its sound outlet is exposed above the upper casing 1, reminding that the gas pressure in the well is higher than the stroke threshold and that there is a risk.

[0031] In another embodiment, the piston plate 20 is a rubber plate with a second seal 21 on its outer edge. The second seal 21 slides with the inner wall of the lower housing 2. The third seal 22, the second seal 21 and the first seal 13 are all O-rings.

[0032] In another embodiment, the elastic ring 15 is made of rubber and has a spiral structure. Its bottom end is attached to the outer edge of the sealing slide 16, and its top end is attached to the outer edge of the carrier plate 7. The preload spring 14 is a cylindrical helical spring, and its top end is connected to the center of the sealing slide 16. The axis of the preload spring 14 is coaxial with the axis of the elastic ring 15.

[0033] The elastic ring 15, made of rubber and featuring a helical structure, possesses excellent elasticity, uniform deformation, and good wear resistance. The cylindrical helical spring structure is stable and, with the aid of inner and outer tube liners, is not easily deformed. The two spring components work together to more efficiently absorb and decompose the high-pressure impact force from downhole, preventing the impact force from concentrating on the components and effectively protecting the temperature sensor 8 and pressure sensing head 9. Simultaneously, the axial design of both ensures uniform force distribution and smooth sliding of the sealing slide 16, preventing buffer failure due to offset or tilting. The elastic ring 15 is tightly fitted to the outer edge of the sealing slide 16 and the outer edge of the carrier plate 7, increasing the effective area of ​​the elastic ring 15 and providing more stable external elastic conditions for the internal preload spring 14.

[0034] The above orientation references do not represent the specific orientations of each component in this implementation scheme. This implementation scheme is only for the convenience of describing the scheme and to make relative descriptions based on the orientations of the references. In reality, the specific orientations of each component are based on their actual installation and use, as well as the orientation descriptions that are customary to those skilled in the art. This is hereby stated.

[0035] The specific embodiments described above further illustrate the inventive purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, or improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sonic variable density logging tool, comprising an upper casing (1) and a lower casing (2) fixedly connected to the upper casing (1), wherein a bottom cover (3) is threadedly connected to the bottom of the lower casing (2), and a heat insulation layer (6) is attached and fixed to the inner walls of both the upper casing (1) and the lower casing (2), characterized in that, The lower housing (2) contains a carrier plate (7), a temperature sensor (8), and a pressure sensing head (9). A processor (10) is fixed on the carrier plate (7). The bottom end of the bottom cover (3) has a through hole (11), and a corrugated sleeve (12) is fixedly installed in the through hole (11). A first sealing element (13) is provided inside the corrugated sleeve (12). The outer wall of the sensing end of the temperature sensor (8) and the outer wall of the sensing end of the pressure sensing head (9) are tightly sealed with the first sealing element (13). The sensing ends of the temperature sensor (8) and the pressure sensor (9) both pass through the first seal (13) and are exposed outside the lower housing (2); inside the lower housing (2), a preload spring (14), an elastic ring (15), and a sealing slide (16) are provided at positions above the pressure sensor (9) and the temperature sensor (8). The sealing slide (16) is slidably disposed between the inner wall of the lower housing (2) and the two sensors, and a piston plate (20) is provided on its outer ring. The outer edge of 20) slides in cooperation with the inner wall of the lower housing (2). The preload spring (14) is vertically disposed inside the lower housing (2), with its top end connected to the bottom surface of the sealing slide (16) and its bottom end connected to the top end of the pressure sensing head (9) and the temperature sensor (8). The elastic ring (15) is vertically disposed inside the lower housing (2), with its top end connected to the bottom surface of the carrier plate (7) and its bottom end connected to the top surface of the sealing slide (16). The sealing slide (16), the preload spring (14), and the elastic ring (15) are all connected in a sliding manner. The ring (15), the corrugated sleeve (12) and the first seal (13) together constitute a sealing buffer linkage structure, which is used to keep the pressure sensing head (9) and the temperature sensor (8) sealed during the sliding buffer process; the bottom surface of the carrier plate (7) is fixed with an inner tube (17), and an outer tube (18) is slidably sleeved on the outside of the inner tube (17). The bottom surface of the carrier plate (7) is provided with a stroke alarm corresponding to the top of the outer tube (18). An alarm is provided inside the upper housing (1), and the alarm is electrically connected to the stroke alarm.

2. The acoustic variable density logging tool according to claim 1, characterized in that, The preload spring (14) is in elastic compression in its natural state. Its elastic force pushes the pressure sensing head (9) and temperature sensor (8) to extend outward along the first seal (13) inside the corrugated sleeve (12). Under the elastic push of the elastic ring (15) on the sealing slide (16), the outer edge of the sealing slide (16) always maintains a sealing sliding fit with the inner wall of the lower sleeve (2).

3. The acoustic variable density logging tool according to claim 2, characterized in that, The top of the upper casing (1) is threadedly connected to a top cover (4), and a lifting ring (5) is fixedly provided on the top of the top cover (4).

4. The acoustic variable density logging tool according to claim 3, characterized in that, The heat insulation layer (6) is annular, and an annular sealing ring (19) is fixed on its annular inner wall. The outer edge of the piston plate (20) slides in conjunction with the inner wall of the annular sealing ring (19).

5. The acoustic variable density logging tool according to claim 4, characterized in that, The temperature sensor (8) and the pressure sensor (9) are both fixed to a connecting plate (23), and the bottom end of the preload spring (14) is connected to the top surface of the connecting plate (23).

6. The acoustic variable density logging tool according to claim 5, characterized in that, The processor (10) is fixed to the top surface of the carrier plate (7). A vertically downward internal tube (17) is fixed in the middle of the bottom surface of the carrier plate (7). An external tube (18) is slidably sleeved on the outside of the internal tube (17). A third sealing element (22) is provided between the inner wall of the external tube (18) and the sliding surface of the outer wall of the internal tube (17). The bottom end of the external tube (18) passes through the sealing slide (16) and enters the preload spring (14) and is fixedly connected to the top surface of the connecting plate (23). A wire hole is opened on the carrier plate (7) and the connecting plate. The upper and lower ends of the wire hole are respectively connected to the cavity of the internal tube (17) and the external tube (18). The travel alarm is set at the top of the external tube (18). The alarm is electrically connected to the travel alarm.

7. The acoustic variable density logging tool according to claim 6, characterized in that, The piston plate (20) is a rubber plate with a second sealing element (21) on its outer edge. The second sealing element (21) slides with the inner wall of the lower sleeve (2). The second sealing element (21), the third sealing element (22) and the first sealing element (13) are all O-rings.

8. The acoustic variable density logging tool according to claim 7, characterized in that, The elastic ring (15) is made of rubber and has a spiral structure. Its bottom end is attached to the outer edge of the sealing slide (16), and its top end is attached to the outer edge of the carrier plate (7). The preload spring (14) is a cylindrical helical spring. Its top end is connected to the center of the sealing slide (16), and the axis of the preload spring (14) is coaxial with the axis of the elastic ring (15) and coaxial with the axis of the lower sleeve (2).

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