Multi-core cable head sealing component for downhole instrument

Abstract

The invention relates to the technical field of petroleum and natural gas exploration and development, and discloses a multi-core cable head sealing member for a downhole instrument, which comprises a multi-core cable and a packaging assembly sleeved outside the multi-core cable, and further comprises a sealing base arranged in the packaging assembly, and a penetrating channel arranged at the axis of the sealing base; the pressure applying piece is arranged on the outer side of the multi-core cable insulating layer in a sleeving mode and located in the penetrating channel, and multi-stage circumferential sealing is formed between the pressure applying piece and the multi-core cable insulating layer and between the pressure applying piece and the penetrating channel; the conical end cover is connected to the end of the packaging assembly and attached to the outer side of the sealing base so that the outer end face of the sealing base can be extruded, and tail end sealing can be achieved. The multi-core cable head sealing component for the downhole instrument aims to solve the problem that an effective circumferential sealing structure is lacked between a packaging assembly and a cable insulating layer, high-pressure fluid is prone to permeating from a gap, and sealing failure is caused.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, specifically to a multi-core cable head sealing component for downhole instruments. Background Technology

[0002] In the field of oil and gas exploration and development, logging and completion operations are key links to ensure the efficient exploitation of oil and gas resources. With the accelerated intelligent transformation of the industry, the requirements for the stability and accuracy of data transmission by downhole instruments have increased significantly. As the core data and power transmission carrier, cables are constantly expanding their application scenarios, from conventional shallow well operations to deep wells, ultra-deep wells, and high-temperature, high-pressure complex oil and gas reservoir operations. In the downhole operating environment, the temperature often reaches -40-150℃, and the pressure can reach 0-70MPa. At the same time, they also face problems such as oil and gas corrosion and mud and sand abrasion. This places extremely high demands on the sealing performance, insulation performance, and mechanical strength of cable joints. To meet the needs of complex downhole working conditions, cable joints need to have the ability to adapt to high-temperature and high-pressure environments, reliable sealing and insulation protection, convenient on-site installation characteristics, and flexible connection compatibility.

[0003] However, most existing cable heads use a single sealing method, which does not form an effective circumferential sealing structure between the encapsulation assembly and the cable. This allows high-pressure fluids to easily seep into the interior through the gap between the cable insulation layer and the encapsulation assembly, causing sealing failure. At the same time, the end of the encapsulation assembly lacks a targeted end sealing design, which prevents the cable head from forming a complete sealing barrier in the axial direction. Oil and gas media under high temperature and high pressure environments can invade from the end, thereby affecting the stability and safety of the electrical connection. This problem of insufficient sealing directly restricts the long-term reliable operation of the cable head in extreme downhole environments. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that high-pressure fluid can easily seep into the gap between the encapsulation assembly and the cable insulation layer due to the lack of an effective circumferential sealing structure, which causes sealing failure. Therefore, this invention proposes a multi-core cable head sealing component for downhole instruments.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A sealing component for a multi-core cable head for downhole instruments includes a multi-core cable and an encapsulation assembly sleeved over the multi-core cable, and further includes: A sealing base is disposed within the encapsulation assembly, and a through-hole is provided at the axial center of the sealing base; The pressure-applying component is sleeved on the outside of the insulation layer of the multi-core cable and located inside the through-channel, forming a multi-level circumferential seal between itself, the insulation layer of the multi-core cable, and the through-channel; A tapered end cap is connected to the end of the encapsulation assembly and fits against the outside of the sealing base to compress the outer end face of the sealing base and achieve end sealing.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the assembly has an assembly area at its core, and a sealed insulating head is connected to the end of the multi-core cable after the outer insulation layer has been removed. The sealed insulating head is located in the assembly area and is used to electrically connect the cable cores.

[0008] Furthermore, the pressure-applying component includes a head pressure-applying ring, a middle pressure-applying ring, and a tail pressure-applying ring. The head pressure-applying ring, the middle pressure-applying ring, and the tail pressure-applying ring are sequentially connected in series and sleeved on the outside of the insulation layer of the multi-core cable, and located in the through-passage, forming an axially progressive sealing structure through multi-stage series connection.

[0009] Furthermore, a first sealing ring is embedded on the outer side of the first pressure ring, the first sealing ring is in contact with the inner surface of the through-channel of the sealing base, and the end of the first pressure ring also abuts against the inner end face of the through-channel. Among them, the end of the multi-core cable after the outer insulation layer is stripped is connected to a core fixing plug for fixing the cable core; The inner surface of the first pressure ring is provided with a first abutting surface, which is arranged along the circumference of the multi-core cable and contacts and seals with the outer surface of the insulation layer of the multi-core cable after the outer insulation layer has been stripped. The inner surface of the first pressure ring is also provided with a first inclined contact surface, which cooperates with the outer surface of the middle pressure ring.

[0010] Furthermore, a second sealing ring is embedded on the outer side of the central pressure ring, and the central pressure ring slides and seals with the inner surface of the through-channel of the sealing base through the second sealing ring; The outer surface of the middle pressure ring is provided with a second inclined contact surface, which cooperates with the first inclined contact surface of the head pressure ring. The end of the second inclined contact surface is provided with a first sealing ring, which is sealed and sleeved on the outside of the multi-core cable. The outer surface of the first sealing ring abuts against the first inclined contact surface of the head pressure ring. The inner surface of the middle pressure ring is provided with a third inclined contact surface, which cooperates with the outer surface of the tail pressure ring.

[0011] Furthermore, the tail pressure ring is threadedly connected to the inner wall of the through-channel of the sealing base; The outer surface of the tail pressure ring is provided with a fourth inclined contact surface, which cooperates with the third inclined contact surface of the middle pressure ring. The end of the fourth inclined contact surface is provided with a second sealing ring, which is sealed and sleeved on the outside of the multi-core cable. The outer surface of the second sealing ring abuts against the third inclined contact surface of the middle pressure ring. When the tail pressure ring is screwed into the sealing base, the fourth inclined contact surface pushes the third inclined contact surface, and the third inclined contact surface pushes the second inclined contact surface. Through the wedge-shaped squeezing action of the inclined surfaces, an axial compression force is applied to the first sealing ring and the second sealing ring, so that they are tightly attached to the cable insulation layer to form a multi-stage series sealing structure.

[0012] Furthermore, the inner surface of the tail pressure ring is provided with a conical groove, and a conical sealing ring is provided in the conical groove. The conical sealing ring is sealed and fitted on the outside of the multi-core cable and fits against the inner wall of the conical groove to form a conical extrusion seal.

[0013] Furthermore, the packaging assembly is connected to the conical end cap via a connector. The outer surface of the connector is provided with a first protrusion, which is located at the connection interface between the packaging assembly and the conical end cap and is embedded in the inner wall of the conical end cap to form an annular seal.

[0014] Furthermore, a connecting hole is provided at the center of the tapered end cap, through which the multi-core cable passes; The inner surface of the conical end cap is provided with an inner conical surface, and the outer surface of the sealing base is provided with an outer conical surface that mates with the inner conical surface; When the conical end cap is threadedly connected to and tightened with the encapsulation assembly, the inner conical surface and the outer conical surface abut against each other and generate radial extrusion force, causing the sealing base to radially shrink and tightly wrap around the outside of the multi-core cable, thereby achieving end conical surface sealing.

[0015] Furthermore, the socket connector and the sealing base cooperate to form an annular groove, and the outer side of the sealing base is provided with a second protrusion that matches the annular groove, and the second protrusion is embedded in the annular groove.

[0016] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: The pressure-applying component of this invention is sleeved on the outside of the insulation layer of a multi-core cable and located within the penetration channel of the sealing base. A multi-level circumferential sealing structure is formed between the cable insulation layer and the penetration channel. Through the layered protection of multiple sealing interfaces, the path of high-pressure fluid seeping into the interior from the gap between the cable insulation layer and the encapsulation assembly is effectively blocked. Secondly, the conical end cap is connected to the end of the encapsulation assembly and fits against the outside of the sealing base. The end seal is achieved by squeezing the outer end face of the sealing base, forming a complete sealing barrier in the axial direction. This effectively prevents oil and gas media in the high-temperature and high-pressure environment from entering from the end. The sealing base, the pressure-applying component, and the conical end cap work together to construct a dual protection system of circumferential multi-level sealing and axial end sealing. This not only blocks the radial leakage channel but also seals the axial intrusion path, forming all-round sealing protection. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the connection structure of a multi-core cable head sealing component for downhole instruments according to the present invention; Figure 2 This is a schematic diagram of the connection structure of another type of multi-core cable head sealing component for downhole instruments according to the present invention.

[0018] In the diagram: 1. Multi-core cable; 2. Encapsulation assembly; 3. Sealing base; 4. Battery core fixing plug; 5. Conical end cap; 6. Sealed insulating head; 7. Head pressure ring; 8. Middle pressure ring; 9. Tail pressure ring; 10. First sealing ring; 11. Second sealing ring; 12. Conical sealing ring; 13. Socket connector; 14. Connection hole. Detailed Implementation

[0019] 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.

[0020] like Figure 1 As shown, this invention provides a sealing component for a multi-core cable head for downhole instruments, including a multi-core cable 1 and an encapsulation assembly 2 sleeved around the multi-core cable 1. The multi-core cable 1 is a red 9-core cable with 9 independent cores, capable of simultaneously transmitting data and supplying power. The cable insulation is made of high-temperature resistant, high-pressure resistant, and wear-resistant materials, with an insulation resistance greater than 22 GΩ, ensuring good insulation and mechanical properties within a temperature range of -40℃ to 150℃. The encapsulation assembly 2 provides overall structural support and protection for the cable head.

[0021] It also includes a sealing base 3, located within the encapsulation assembly 2, with a through-hole at the axial center of the sealing base 3. The sealing base 3 is preferably made of stainless steel, possessing high strength, high rigidity, and good sealing compatibility, providing stable support for the entire sealing structure. The through-hole extends the entire axial length of the sealing base 3, and its inner diameter is designed to be slightly larger than the outer diameter of the multi-core cable 1 to facilitate the installation of the pressure-applying component and the deformation space of the sealing material. The inner wall of this channel has a threaded structure for threaded connection with subsequent pressure-applying components.

[0022] The pressure-applying element is sleeved on the outside of the insulation layer of the multi-core cable 1 and located inside the penetration channel, forming a multi-stage circumferential seal between itself, the insulation layer of the multi-core cable 1, and the penetration channel. Specifically, the pressure-applying element includes a first pressure-applying ring 7, a middle pressure-applying ring 8, and a last pressure-applying ring 9. The first pressure-applying ring 7, the middle pressure-applying ring 8, and the last pressure-applying ring 9 are sequentially connected in series and sleeved on the outside of the insulation layer of the multi-core cable 1, and located inside the penetration channel, forming an axially progressive sealing structure through multi-stage series connection. This series configuration allows the axial compressive force to be transmitted step by step, with each pressure-applying ring applying pressure to the adjacent sealing material, thereby forming multiple continuous sealing barriers between the cable insulation layer and the inner wall of the penetration channel.

[0023] Furthermore, a first sealing ring is embedded on the outer side of the first pressure ring 7. The first sealing ring is preferably made of NBR material with a hardness of 90 DURO, possessing good elasticity and sealing performance, and is oil-resistant and aging-resistant. The first sealing ring and the inner surface of the through-channel of the sealing base 3 are in contact with each other to form a circumferential sealing interface. The end of the first pressure ring 7 also abuts against the inner end face of the through-channel, forming axial positioning and preventing axial displacement of the pressure ring under pressure.

[0024] Meanwhile, after the outer insulation layer is stripped, the end of the multi-core cable 1 is connected to a core fixing plug 4 for securing the cable cores. The core fixing plug 4 is made of stainless steel or PEEK material, possessing good mechanical strength and insulation properties. When PEEK material is used, its temperature resistance can reach 250℃, providing reliable insulation protection for the cable cores.

[0025] The inner surface of the first pressure ring 7 is provided with a first abutting surface, which is arranged circumferentially along the multi-core cable 1 and contacts and seals with the outer surface of the insulation layer of the multi-core cable 1 after the outer insulation layer has been stripped, forming a first radial sealing interface. It should also be noted that an internal thread is provided on the inner wall of the first inclined contact surface, and an external thread that matches the internal thread is provided on the outer side of the battery cell fixing plug 4. The battery cell fixing plug 4 is connected to the inner wall of the first inclined contact surface by a threaded connection. The inner surface of the first pressure ring 7 is also provided with a first inclined contact surface, which is matched with the outer surface of the middle pressure ring 8. This inclined surface is usually designed as a conical structure with a cone angle of 5°-15° so as to generate a radial extrusion force under axial pressure.

[0026] A second sealing ring is embedded on the outer side of the central pressure ring 8. The central pressure ring 8 slides and seals against the inner surface of the through-channel of the sealing base 3 through the second sealing ring. The second sealing ring is also preferably made of 90NBR material, which has good elasticity and sealing performance and is resistant to oil and gas corrosion. This sliding seal design allows the central pressure ring 8 to move axially during installation while maintaining a circumferential seal with the inner wall of the sealing base 3. The outer surface of the central pressure ring 8 is provided with a second inclined contact surface, which matches the first inclined contact surface of the first pressure ring 7. The cone angles of the two inclined surfaces match to ensure a tight fit. A first sealing ring 10 is provided at the end of the second inclined contact surface. The first sealing ring 10 is fitted onto the outside of the multi-core cable 1, and the outer surface of the first sealing ring 10 abuts against the first inclined contact surface of the first pressure ring 7. The first sealing ring 10 is made of highly elastic rubber material. Under the clamping of the two inclined surfaces, the axial compression force is converted into radial extrusion force, so that the sealing ring tightly wraps the cable insulation layer, forming a second radial seal. The inner surface of the middle pressure ring 8 is provided with a third inclined contact surface, which is in contact with the outer surface of the tail pressure ring 9.

[0027] The tail pressure ring 9 is threadedly connected to the inner wall of the through-channel of the sealing base 3, and this threaded connection provides the source of axial clamping force for the entire pressure system. The tail pressure ring 9 is made of stainless steel and has sufficient mechanical strength. The outer surface of the tail pressure ring 9 is provided with a fourth inclined contact surface, which mates with the third inclined contact surface of the middle pressure ring 8. The end of the fourth inclined contact surface is provided with a second sealing ring 11, which is sealed and fitted on the outside of the multi-core cable 1. The outer surface of the second sealing ring 11 abuts against the third inclined contact surface of the middle pressure ring 8.

[0028] When the tail pressure ring 9 is screwed into the sealing base 3, the fourth inclined contact surface pushes the third inclined contact surface, and the third inclined contact surface pushes the second inclined contact surface. Through the wedge-shaped squeezing action of the inclined surfaces, axial compression force is applied to the first sealing ring 10 and the second sealing ring 11, making them tightly fit with the cable insulation layer and forming a multi-stage series sealing structure. This pressure transmission mechanism is similar to the hydraulic amplification effect. Every time the tail pressure ring 9 is screwed in at a certain angle, it is converted into axial displacement through the lead of the thread. This axial force is transmitted and amplified sequentially through each inclined surface, ultimately causing all sealing materials to be compressed and deformed simultaneously. Since rubber materials have near-incompressible properties, axial compression inevitably leads to radial expansion, causing the sealing rings to tightly fill the annular gap between the cable insulation layer and the inner metal wall, forming independent sealing rings at multiple axial positions. Even if a small leak occurs in one seal, the other sealing layers can still maintain the overall sealing performance.

[0029] Preferably, the inner surface of the tail pressure ring 9 is further provided with a conical groove, and a conical sealing ring 12 is provided in the conical groove. The conical sealing ring 12 is fitted onto the outside of the multi-core cable 1 and fits against the inner wall of the conical groove to form a conical compression seal. The cone angle of the conical groove is usually designed to be 45°-60°. When the tail pressure ring 9 is tightened, the conical sealing ring 12 is compressed by the conical surface, and deforms simultaneously in the radial and axial directions. This conical seal has a stronger self-tightening effect than the planar seal and has a better sealing effect under high pressure.

[0030] An assembly area is located at the center of the encapsulation assembly 2. A sealed insulating head 6 is connected to the end of the multi-core cable 1 after the outer insulation layer has been stripped. The sealed insulating head 6, situated within the assembly area, is used for electrical connection of the cable cores. The sealed insulating head 6 can employ a potting encapsulation structure. The potting material possesses high-temperature resistance, high-pressure resistance, and oil / gas corrosion resistance, protecting the internal solder joints and electrical connections from corrosion in the downhole environment. This assembly area provides ample operating space, allowing the sealed insulating head 6 to be easily soldered to sensor pots or circuit boards, achieving integrated connection for data signal transmission and power supply. Simultaneously, during wiring, the cable can be cut at any point, and its length can be flexibly adjusted according to actual operational needs, with an error range controlled within ±5mm. It also allows for free soldering of cables to circuit boards and sensors of different specifications without the need for customized adapters, adapting to the connection requirements of different types of downhole instruments, improving equipment deployment flexibility and versatility, and reducing equipment adaptation costs.

[0031] A conical end cap 5 is connected to the end of the encapsulation assembly 2 and fits against the outer side of the sealing base 3 to compress the outer end face of the sealing base 3, achieving an end seal. A connecting hole 14 is provided at the axial center of the conical end cap 5, through which the multi-core cable 1 passes. The inner diameter of the connecting hole 14 is slightly larger than the outer diameter of the cable, facilitating cable passage while providing space for the installation of sealing material. The inner surface of the conical end cap 5 has an inner conical surface, and the outer surface of the sealing base 3 has an outer conical surface that mates with the inner conical surface. When the conical end cap 5 is threadedly connected and tightened to the encapsulation assembly 2, the inner and outer conical surfaces abut against each other, generating radial compressive force, causing the sealing base 3 to radially contract and tightly wrap around the outer side of the multi-core cable 1, achieving an end conical surface seal. This conical sealing principle utilizes the angle conversion of the conical surface to transform the axial tightening force into a radial contraction force. When the conical end cap 5 is tightened, its inner conical surface slides along the outer conical surface of the sealing base 3, pushing the sealing base 3 to contract radially, thereby forming a radial covering pressure on the outside of the cable. This pressure makes the contact between the sealing base 3 and the cable tighter, effectively preventing high-pressure fluid from entering from the end.

[0032] The encapsulation assembly 2 is connected to the conical end cap 5 via a socket connector 13. The outer surface of the socket connector 13 has a first protrusion located at the interface between the encapsulation assembly 2 and the conical end cap 5, and embedded in the inner wall of the conical end cap 5 to form an annular seal, preventing external media from seeping in along the interface. The socket connector 13 is made of stainless steel. The first protrusion is preferably designed as an annular boss structure with a height of 0.5-2mm. When the conical end cap 5 and the socket connector 13 are threaded together, the first protrusion is embedded in the mating groove on the inner wall of the conical end cap 5, forming a labyrinthine seal structure, effectively blocking the intrusion path of external media.

[0033] Furthermore, the socket connector 13 and the sealing base 3 form an annular groove. The outer side of the sealing base 3 is provided with a second protrusion that matches the annular groove, and the second protrusion is embedded in the annular groove. The annular groove provides axial restraint and circumferential positioning for the second protrusion, preventing the sealing base 3 from undergoing axial displacement or circumferential rotation under pressure. This restraint structure ensures that the sealing base 3 remains stable in position when subjected to internal sealing pressure and external high-pressure fluid impact, avoiding sealing failure due to positional displacement. A corresponding sealing gasket is also provided between the socket connector 13 and the sealing base 3 to seal the gap between them.

[0034] The conical end cap 5 is made of stainless steel. The conical structure design causes the outer diameter to gradually shrink from 56.17mm to the inner diameter of the connecting hole 14 of 10.85mm. This conical transition not only allows the pressure generated during the thread tightening process to be more concentrated on the sealing area, but also facilitates the diversion of external fluids during downhole operations, reduces the direct impact on the cable head end, and improves the overall structure's impact resistance and service life.

[0035] A sealing gasket is also provided between the package assembly 2 and the socket connector 13. When the package assembly 2 and the socket connector 13 are tightened, the inner end face of the package assembly 2 applies an axial compressive force to the sealing gasket. Due to its good elasticity, the sealing gasket expands radially after being axially compressed, filling the annular gap between the package assembly 2 and the socket connector 13 and forming a sealing barrier.

[0036] Installation and working principle: During actual installation, the multi-core cable 1, which has been cut to the correct size, is first passed through the conical end cap 5, conical sealing ring 12, tail pressure ring 9, second sealing ring 11, middle pressure ring 8, first sealing ring 10, and head pressure ring 7 in sequence. At this time, each component is in a loose state. Since the inner diameter of each component is larger than the outer diameter of the cable, it can pass through smoothly. Then the cable is stripped, removing a section of the outer insulation to expose nine independent wires. The stripping length is determined according to the actual electrical connection requirements, but the integrity of the cable insulation must be maintained outside the stripped section. Next, insert the battery cell fixing plug 4 into the position where the cable insulation layer has been stripped, so that the plug end face is in close contact with the remaining insulation layer of the cable. Then, tighten the head pressure ring 7 to the battery cell fixing plug 4 through the thread to form the first stage of mechanical fixation, which effectively prevents the cable from falling due to its own weight. Insert the fixed cable assembly into the inner cavity of the sealing base 3 to ensure that all sealing components are inside the internal space of the sealing base 3. Then tighten the tail pressure ring 9 to the sealing base 3 through the thread. During the tightening process, the axial compression force is transmitted to each level of sealing material in sequence, causing it to undergo elastic deformation and tightly adhere to the cable surface and the inner metal wall, forming multiple continuous sealing barriers. After the mechanical seal is completed, the 9 wire cores and the sealing insulation head 6 are exposed inside the package assembly 2 for soldering to the circuit board or other components to achieve electrical connection. Since the soldering area and the sealing area are spatially separated, the soldering operation will not affect the established sealing structure. The soldering area is located inside the package assembly 2. Finally, the conical end cap 5 is tightened to the socket connector 13 via threads. The inner conical surface of the conical end cap 5 and the outer conical surface of the sealing base 3 press against each other, causing the sealing base 3 to radially contract and tightly wrap the cable. At the same time, the first sealing ring 10 and the second sealing ring 11 are compressed to form a terminal seal, thus completing the assembly of the entire cable head.

[0037] Sealing mechanism: After assembly, the entire cable head forms a dual protection system of "circumferential multi-level sealing + axial end sealing". In the circumferential direction, multiple sealing defenses are established from the inside to the outside: the first layer is the original insulation of the cable, which serves as the first insulation barrier to protect the wire core from corrosion; the second layer is a precision sealing combination composed of the first sealing ring and the second sealing ring; the third layer is the first sealing rubber ring 10, which forms a radial seal under the clamping of the inclined surfaces of the head pressure ring 7 and the middle pressure ring 8; the fourth layer is the second sealing rubber ring 11, which forms a radial seal under the clamping of the inclined surfaces of the middle pressure ring 8 and the tail pressure ring 9. In the axial direction, the conical end cap 5 and the conical sealing ring 12 cooperate to form an end seal. The series configuration of multiple sealing barriers ensures that even if one seal fails partially, the other sealing layers can still maintain the overall sealing performance of the system, thus achieving a redundant protection design. Under high pressure, the elastic deformation of the sealing material increases, making it fit more tightly against the sealing surface and forming a self-tightening sealing effect. The higher the pressure, the better the sealing effect. Under high temperature, PEEK material components can maintain stable performance at 250℃, while 90NBR material provides excellent resistance to oil and gas corrosion in the range of -40℃ to 150℃. The two materials exert their best performance in different temperature ranges, realizing the design concept of materials working together.

[0038] It should also be noted that the cone angle of the conical end cap 5 can be adjusted within the range of 30°-70°. A smaller cone angle can generate a larger radial contraction force, which is suitable for ultra-high pressure conditions; while a larger cone angle facilitates quick installation and disassembly, which is suitable for occasions that require frequent maintenance.

[0039] like Figure 2 As shown, the soldering cavity inside the package assembly 2 can accommodate multiple circuit boards or sensor modules. Electrical connections are completed by connecting cables to both ends of the package assembly 2, which can meet the needs of multi-module connections for complex downhole instruments.

[0040] Through the coordinated operation of multi-stage circumferential sealing and end sealing, multiple continuous sealing barriers are formed inside the cable head, effectively blocking the infiltration path of high-pressure fluids. The inclined wedge-shaped extrusion mechanism efficiently converts axial clamping force into radial sealing force, ensuring a tight fit between the sealing material and the cable surface. The conical end cap 5 and the conical base 3 achieve reliable end sealing, forming an axial sealing barrier. The entire device can be assembled solely through mechanical structures, eliminating the need for complex processes such as vulcanization and gluing. On-site operation is simple, and it can be fabricated at any location on the cable, offering high flexibility. Because irreversible connection technology is not used, the cable head can be disassembled and repaired without damage, reducing maintenance costs. The overall structure can operate stably for extended periods within a temperature range of -40℃ to 150℃ and a pressure range of 0 to 70MPa, meeting the stringent requirements of extreme downhole operating environments such as deep and ultra-deep wells.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-conductor cable head sealing member for downhole instruments, comprising a multi-conductor cable (1) and a packaging assembly (2) which is fitted over the multi-conductor cable (1), characterized in that, Also include: The sealing base (3) is provided in the packaging assembly (2), and the axial center of the sealing base (3) is provided with a penetrating channel; The pressure applying member is sleeved on the outside of the insulation layer of the multi-core cable (1) and located in the penetrating channel, and forms a multi-stage circumferential seal between the multi-core cable (1) insulation layer and the penetrating channel; The conical end cover (5) is connected to the end of the packaging assembly (2) and is attached to the outside of the sealing base (3) to extrude the outer end surface of the sealing base (3) and realize end sealing.

2. A multi-conductor cable head seal member for use with a downhole instrument according to claim 1, wherein, The axial center of the packaging assembly (2) is provided with an assembly area, and the multi-core cable (1) after removing the outer insulation layer is connected with a sealing insulation head (6), and the sealing insulation head (6) is arranged in the assembly area and used for electrically connecting the cable core.

3. A multi-conductor cable head seal member for use with a downhole instrument according to claim 1, wherein, The pressure applying member includes a first pressure applying ring (7), a middle pressure applying ring (8) and a tail pressure applying ring (9), which are sequentially and serially sleeved on the outside of the insulation layer of the multi-core cable (1) and located in the penetrating channel, and form an axial progressive sealing structure through multi-stage series connection.

4. A multi-conductor cable head seal member for use with a downhole instrument according to claim 3, wherein, The outside of the first pressure applying ring (7) is embedded with a first sealing ring, and the first sealing ring is attached to the inner surface of the penetrating channel of the sealing base (3), and the end of the first pressure applying ring (7) is also abutted to the inner end surface of the penetrating channel; Wherein, the multi-core cable (1) after removing the outer insulation layer is connected with an electric core fixing plug (4) for fixing the cable core; The inner surface of the first pressure applying ring (7) is provided with a first abutting surface, and the first abutting surface is arranged along the circumference of the multi-core cable (1) and is in contact with the outer surface of the insulation layer of the multi-core cable (1) after removing the outer insulation layer. The inner surface of the first pressure applying ring (7) is also provided with a first inclined abutting surface, and the first inclined abutting surface cooperates with the outer surface of the middle pressure applying ring (8).

5. A multi-conductor cable head seal member for use with a downhole instrument according to claim 4, wherein, The outside of the middle pressure applying ring (8) is embedded with a second sealing ring, and the middle pressure applying ring (8) is slidingly sealed with the inner surface of the penetrating channel of the sealing base (3) through the second sealing ring; The outer surface of the middle pressure applying ring (8) is provided with a second inclined abutting surface, and the second inclined abutting surface cooperates with the first inclined abutting surface of the first pressure applying ring (7), and the end of the second inclined abutting surface is provided with a first sealing rubber ring (10), and the first sealing rubber ring (10) is sleeved on the outside of the multi-core cable (1), and the outer surface of the first sealing rubber ring (10) is abutted to the first inclined abutting surface of the first pressure applying ring (7); The inner surface of the middle pressure applying ring (8) is provided with a third inclined abutting surface, and the third inclined abutting surface cooperates with the outer surface of the tail pressure applying ring (9).

6. A multi-conductor cable head seal member for use with a downhole instrument according to claim 5, wherein, The tail pressure applying ring (9) is connected to the inner wall of the penetrating channel of the sealing base (3) through threads; The outer surface of the tail pressure ring (9) is provided with a fourth inclined fitting surface which cooperates with the third inclined fitting surface of the middle pressure ring (8), and the end of the fourth inclined fitting surface is provided with a second sealing rubber ring (11) which is sealingly sleeved on the outside of the multi-core cable (1), and the outer surface of the second sealing rubber ring (11) abuts against the third inclined fitting surface of the middle pressure ring (8); When the tail pressure ring (9) is screwed into the sealing base (3), the fourth inclined fitting surface pushes the third inclined fitting surface, and the third inclined fitting surface pushes the second inclined fitting surface, so that the first sealing rubber ring (10) and the second sealing rubber ring (11) are axially compressed by the wedge-shaped extrusion effect of the inclined surfaces, and are tightly fitted with the cable insulation layer to form a multi-stage series sealing structure.

7. A multi-conductor cable head seal member for use with a downhole instrument according to claim 6, wherein, The inner surface of the tail pressure ring (9) is further provided with a conical groove, and a conical sealing rubber ring (12) is arranged in the conical groove, the conical sealing rubber ring (12) is sealingly sleeved on the outside of the multi-core cable (1) and is fitted with the inner wall surface of the conical groove to form a conical extrusion sealing.

8. A multi-conductor cable head seal member for use with a downhole instrument according to claim 1, wherein, The sealing assembly (2) is connected with the conical end cover (5) through a socket joint (13), the outer surface of the socket joint (13) is provided with a first protruding part which is located at the connection interface between the sealing assembly (2) and the conical end cover (5) and is embedded in the inner wall of the conical end cover (5) to form an annular sealing.

9. A multi-conductor cable head seal member for use with a downhole instrument according to claim 1, wherein, The conical end cover (5) is provided with a connecting hole (14) at the center, and the multi-core cable (1) passes through the connecting hole (14); The inner surface of the conical end cover (5) is provided with an inner conical surface, and the outer surface of the sealing base (3) is provided with an outer conical surface which cooperates with the inner conical surface; When the conical end cover (5) is threadedly connected with the sealing assembly (2) and is fastened, the inner conical surface and the outer conical surface abut against each other and generate a radial extrusion force, so that the sealing base (3) is radially contracted and tightly wrapped on the outside of the multi-core cable (1) to realize the end conical surface sealing.

10. A multi-conductor cable head seal member for use with a downhole instrument according to claim 8, wherein, The socket joint (13) and the sealing base (3) cooperatively form an annular groove, and the outside of the sealing base (3) is provided with a second protruding part which is adapted to the annular groove and is embedded in the annular groove.

Images