High-temperature and high-pressure small-diameter caliper

Abstract

The utility model provides a high-temperature high-pressure small-diameter caliper which comprises an upper connector, a pushing short section and a lower connector which are connected in sequence, the upper connector comprises a first connecting shell and a multi-core shell which are connected with each other, the other end of the multi-core shell is connected with the pushing short section, a first multi-core socket is installed in the multi-core shell, and a second multi-core socket is installed in the lower connector. The outer surface of the first multi-core socket is provided with a sealing section with a sealing ring and a supporting section, the two axial ends of the first multi-core socket are respectively provided with a pin seat, and the inner surface of the multi-core shell is provided with a first convex ring which is in contact with the sealing section and blocks the supporting section. According to the utility model, a split structure is adopted, so that the position of the upper joint can be kept fixed when the upper joint resists high pressure through the multi-core socket with the supporting section, the whole caliper does not need to be improved and materials do not need to be replaced, the equipment cost is greatly reduced, and the caliper under normal pressure can be directly used for caliper measurement of a high-pressure well.

Description

Technical Field

[0001] This utility model relates to the field of petroleum exploration, and in particular to a small-diameter wellbore instrument that is resistant to high temperature and high pressure and can connect different pressure equipment by changing the connectors at both ends of the pusher. Background Technology

[0002] In the field of oil exploration, the diameter of a well formed during drilling is not a constant. This diameter varies depending on the formation material, the drilling speed, or the drilling method.

[0003] In addition, after the well is drilled, geological changes can cause changes in the well diameter at different depths, such as tilting, collapse, shrinkage, and high temperature. To facilitate subsequent work, it is necessary to monitor the changes in well diameter in real time.

[0004] Existing caliper instruments are mostly designed for measuring the caliper diameter of large-diameter oil wells (such as those larger than 5.5 inches). For example, patent application number 202322095181.8 discloses a four-arm caliper instrument in which each arm can independently push and lean. It uses multiple motors to control a measuring rod to measure the caliper diameter of the oil well. Although this improves the adaptability of measurement for different caliper diameters, it is limited to measuring the caliper diameter of large-diameter oil wells due to its size. Its structure is completely unsuitable for measuring the caliper diameter of small-diameter oil wells (such as those around 4.5 inches).

[0005] Measuring small-diameter oil wells is not simply a matter of miniaturizing existing large-diameter oil well measuring tools. It requires consideration of the pressure conditions of the entire measuring equipment, the internal wiring, the connections between components, and subsequent maintenance.

[0006] In addition, in terms of downhole pressure resistance, most domestic caliper instruments can only work under a pressure of 140 MPa. When they need to work under high temperature and high pressure, such as 260 MPa, the structure of the caliper instrument needs to be changed and the corresponding materials replaced, which makes the cost of a caliper instrument working under high pressure more than 10 times that of a caliper instrument working under low pressure.

[0007] Therefore, there is a need for a low-cost wellbore gauge that can operate under high temperature and high pressure. Utility Model Content

[0008] The purpose of this invention is to provide a small-diameter wellbore instrument that is resistant to high temperature and high pressure, and can connect to different pressure equipment by changing the connectors at both ends of the pusher.

[0009] Specifically, this utility model provides a high-temperature, high-pressure, small-diameter wellbore gauge, comprising an upper connector, a push-fit sub, and a lower connector connected in sequence.

[0010] The upper connector includes a first connecting housing and a multi-core housing that are connected to each other. The other end of the multi-core housing is connected to a push-back short section. A first multi-core socket is installed inside the multi-core housing. The outer surface of the first multi-core socket is provided with a sealing section and a support section with a sealing ring. The diameter of the support section is larger than the diameter of the sealing section. Pin seats are provided at both ends of the first multi-core socket along the axial direction. A first convex ring is provided on the inner surface of the multi-core housing that contacts the sealing section and blocks the support section.

[0011] The lower connector includes a second connecting housing connected to the push-back short section, and a second multi-core socket with the same structure as the first multi-core socket installed inside the second connecting housing. A second protruding ring with the same structure as the first protruding ring is provided on the inner surface of the second connecting housing.

[0012] The first multi-core socket has pins at both ends that are connected to the first connecting housing and the multi-hole socket in the push-back section, respectively. The second multi-core socket has pins at one end that are connected to the multi-hole socket in the push-back section, and the other end that is connected to the multi-hole socket in the second connecting housing.

[0013] In one embodiment of this utility model, the first multi-core housing and the second multi-core housing have the same interface as the push-fit short section, and the first multi-core housing and the second multi-core housing can be interchanged in their installation positions relative to the push-fit short section.

[0014] In one embodiment of the present invention, a circuit base is installed inside the connecting housing. The outer surface of the circuit base is surrounded by three planes, and an axial channel is provided inside. Each plane has an opening at both ends of its axial direction that communicates with the axial channel.

[0015] In one embodiment of this utility model, one end of the circuit base is provided with a tube for inserting the multi-hole socket, and the other end is provided with a baffle that contacts the inner retaining ring of the connecting housing. The tube and the baffle are respectively connected to the axial channel.

[0016] In one embodiment of this utility model, the push-fitting section includes a hydraulic balancing part for maintaining internal and external pressure balance, a power part for providing power output, a lead screw part for converting rotational power into linear power, a measuring push part for outputting thrust using a push rod, and a push-fitting part controlled by the push rod, wherein:

[0017] The push-back part includes a push-back base and four push-back arms evenly distributed around the circumference of the push-back base. Each push-back arm includes a main arm, a secondary arm, a main arm support rod, a secondary arm support rod, and a push-back plate. One end of the main arm, the secondary arm, and the main arm support rod are rotatably connected to the push-back base, and the other end is hinged to the push-back plate. After connection, the main arm and the secondary arm are positioned opposite each other and form a trapezoidal shape when opened. The main arm support rod is installed within the range formed by the main arm and the secondary arm and is parallel to the main arm. A sliding groove is provided on the secondary arm. One end of the secondary arm support rod is installed in the sliding groove through a pin, and the other end is hinged to the push-back base outside the secondary arm.

[0018] In one embodiment of the present invention, a receiving groove for accommodating the pushing arm is provided on the pushing base, and an axial auxiliary arm slide groove is provided in the receiving groove. The connecting end of the auxiliary arm and the pushing base is installed in the auxiliary arm slide groove by a pin.

[0019] In one embodiment of this utility model, a limiting block is installed in the receiving groove outside the connection end between the main arm and the push base to limit the opening angle of the main arm.

[0020] In one embodiment of this utility model, a storage groove for accommodating the auxiliary arm is provided on the side of the auxiliary arm support rod opposite to the auxiliary arm.

[0021] In one embodiment of this utility model, a connector is installed between the hydraulic balancing unit and the power unit to connect the two. The connector includes a left housing that is plugged into the hydraulic balancing unit via a key, a right housing that is movably plugged into the power unit, and a multi-pin plug. A third multi-hole socket that is plugged into the multi-pin plug is installed in the left housing and the right housing respectively.

[0022] In one embodiment of this utility model, a decompression disc is installed between the right housing and the power unit.

[0023] The upper and lower connectors of this utility model adopt the same structure, which can be easily replaced according to the measuring equipment to be installed each time the well is lowered, without the need to use another push-back short section. The same push-back short section can meet the connection of different measuring equipment by only replacing the connectors at both ends, which not only simplifies the installation process, but also saves equipment costs.

[0024] This invention decomposes the existing multi-core socket, which is directly connected at both ends by cables, into a separate structure consisting of multi-hole sockets at both ends and a multi-core socket with pins in the middle. This allows the upper connector to be directly disconnected from the push-fit section without the need for additional adapters or sockets. This not only facilitates signal connection between connected components but also, thanks to the multi-core socket with a support section, maintains its position under high pressure, eliminating the need to modify the entire caliper or replace materials, significantly reducing equipment costs. Furthermore, it allows the caliper under normal pressure to be directly used for caliper measurement in high-pressure wells. By using a sequentially connected installation structure for each component, the diameter of the push-fit section itself can be greatly reduced. This design allows for the manufacture of calipers suitable for sizes ranging from 4.5 to 20 inches, and the caliper can also withstand high-temperature and high-pressure environments downhole. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the wellbore gauge structure of this utility model;

[0026] Figure 2 This is a schematic diagram of the upper connector in this utility model;

[0027] Figure 3 This is a schematic diagram of the lower connector in this utility model;

[0028] Figure 4 This is a schematic diagram of the circuit base structure in this utility model;

[0029] Figure 5 yes Figure 4 Radial sectional view;

[0030] Figure 6 This is a schematic diagram of the push-back part in this utility model;

[0031] Figure 7 This is a schematic diagram of the plug-in structure in this utility model. Detailed Implementation

[0032] The structure and working process of this solution will be further described below through specific implementation methods and accompanying drawings. This solution is an improvement based on the solution of application number 202422866356.5. For the parts of the structure and working principle not described in detail below, please refer to the aforementioned patent. This solution only describes the improvement points in detail.

[0033] In the following description, "left end" refers to the left side of the image when facing the screen, and "right end" refers to the right side of the image when facing the screen. In this solution, all locations requiring protection against hydraulic oil and / or mud penetration are equipped with appropriate static or dynamic sealing strips, which will not be repeated below.

[0034] like Figure 1As shown, this embodiment discloses a high-temperature, high-pressure, small-diameter wellbore gauge, which includes an upper connector 1, a push-off sub 2, and a lower connector 3 connected in sequence.

[0035] like Figure 2 As shown, the upper connector 1 is used to connect other downhole measuring equipment connected to the push-back sub 2, including a first connecting housing 11 and a multi-core housing 12 connected together by threads, and the other end of the multi-core housing 12 is connected to the push-back sub 2 by a clamp.

[0036] A first multi-core socket 13 for transmitting cable signals is installed inside the multi-core housing 12. The outer surface of the first multi-core socket 13 is provided with a sealing section 131 with a sealing ring and a support section 132, wherein the diameter of the support section 132 is larger than the diameter of the sealing section 131. Pin seats 133 are respectively provided at both ends of the first multi-core socket 13. A first protrusion ring 111 is provided on the inner surface of the first multi-core housing 11, which contacts the sealing section 131 and blocks the support section 132.

[0037] like Figure 3 As shown, the lower connector 7 includes a second connecting housing 71 connected to the push-back short section 2 by a clamp, and a second multi-core socket 72 installed in the second connecting housing 71. A second protrusion 711 with the same structure as the first protrusion 111 is provided on the inner surface of the second connecting housing 71.

[0038] After connection, the pin seats 133 at both ends of the first multi-core socket 13 are respectively inserted into the first connecting housing 11 and the first multi-hole socket 112 in the push-short section 2; the pin seat 721 at one end of the second multi-core socket 72 is inserted into the second multi-hole socket 722 in the push-short section 2, and the other end is inserted into the second multi-hole socket 722 in the second connecting housing.

[0039] In this design, the upper connector 1 and the lower connector 7 have essentially the same structure, differing only in their connection structure with adjacent measuring devices. Therefore, the upper connector 1 and the lower connector 7 can be adjusted to their respective installation positions according to the different requirements of the connected measuring devices. That is, the upper connector 1 can be installed at the position of the lower connector 7, and vice versa. Alternatively, the upper connector 1 can be installed at each end of the push-abutment section 2, or the lower connector 7 can be installed separately. Here, "different requirements of the measuring devices" refers to both different measuring devices and situations where the same measuring device has different pressure requirements.

[0040] After the upper connector 1 and the lower connector 7 adopt the same structure, the connectors can be easily replaced according to the measuring equipment to be installed each time the well is run down, without the need to replace other push-back short sections. This allows the same push-back short section to meet the connection requirements of different measuring equipment by only replacing the connectors at both ends, which not only simplifies the installation process but also saves equipment costs.

[0041] The first multi-core socket 13 and the second multi-core socket 72, located inside the upper connector 1 and the lower connector 7, have the same structure. Therefore, the installation method and working principle of the second multi-core socket 72 will not be repeated here.

[0042] The push-in sub 2 is filled with hydraulic oil to keep it in balance with the external downhole pressure; however, the upper joint 1 and lower joint 7 need to be connected to cables and installed with circuit boards, so they cannot be filled with hydraulic oil, but only with air. The internal and external pressure balance of this section needs to be supported by the wall thickness.

[0043] Taking the above connector 1 as an example, the first multi-core socket 13 is inserted into the multi-core housing 12 from the side near the push-back section 2. The sealing section 131 is inserted into the first convex ring 111 and forms a seal with the inner surface of the first convex ring 111 through the sealing strip installed on the outer surface, which is used to prevent air and hydraulic oil from penetrating each other on both sides. The support section 132 is blocked by the side of the first convex ring 111. When the multi-core housing 111 is connected to the push-back section 2, the pin seat 133 on the first multi-core socket 13 will be inserted into the multi-hole socket 112 located in the push-back section 2, so that the two can achieve signal connection. When the first connecting housing 11 is connected to the multi-core housing 12, the multi-hole socket 112 located in the first connecting housing 11 will be inserted into the pin seat 133 at this end of the first multi-core socket 13, thereby forming a signal connection.

[0044] Since the push-fit sub 2 is filled with hydraulic oil, and the pressure of the hydraulic oil increases with the increase of downhole pressure, the high pressure of the hydraulic oil will be transmitted to the first multi-core socket 13. At this time, due to the obstruction of the support section 132 by the first convex ring 111, the pressure on the first multi-core socket 13 can be transferred to the connection between the multi-core housing 12 and the push-fit sub 2, preventing the first multi-core socket 13 from detaching from the multi-core housing 12 due to excessive force, thereby enabling the first multi-core socket 13 to withstand higher pressures, such as 260 MPa.

[0045] This solution breaks down the existing multi-core socket that is directly connected by cables at both ends into a split structure consisting of multi-hole sockets at both ends and a multi-core socket with a pin socket in the middle. This allows the upper connector 1 to be directly disconnected when it is detached from the push-button section 2, without the need to add corresponding adapter plugs or sockets. This not only facilitates signal connection between connected components, but also allows the first multi-core socket 13 with a support section 132 to maintain its fixed position when resisting high pressure. This eliminates the need to modify the entire caliper and replace materials, greatly reducing equipment costs. Furthermore, it allows the caliper under normal pressure to be directly used for caliper measurement in high-pressure wells.

[0046] The installation method and effect of the second multi-core socket 72 within the second connecting housing 71 are the same as those of the first multi-core socket 13, and will not be repeated here.

[0047] like Figure 4 , 5 As shown, in one embodiment of the present invention, in order to facilitate the installation of the control circuit board, a circuit base 10 is installed in the first connecting housing 11. The circuit base 10 is a hollow frame surrounded by three planes 101, and an axial channel 102 is provided inside. Each plane 101 has an opening 103 at both ends of its axial direction that communicates with the axial channel 102.

[0048] By using three planes 101 to mount different circuit boards or different parts of the same circuit board, the heat dissipated by the circuit board can be dispersed, and the cables connected to each circuit board can enter the internal axial channel 102 through the openings 103 on each plane 101, which facilitates wiring.

[0049] Furthermore, to facilitate the installation of the circuit base 10, a tube 104 for inserting into the first multi-hole socket 112 inside the first connecting housing 11 is provided at one end of the circuit base 10, and a baffle 105 that contacts the retaining ring 113 inside the first connecting housing 11 is provided at the other end. The tube 104 and the baffle 105 are respectively connected to the axial channel 102. The baffle 105 is used to control the insertion depth of the circuit base 10 inside the first connecting housing 11, while the tube 104 not only restricts the insertion position of the first multi-hole socket 112, but also forms an abutment with the multi-core housing 12, so that when the circuit base 10 is squeezed by the multi-core housing 12, the baffle 105 supports and maintains the stability of the circuit base 10.

[0050] like Figure 1 As shown, in one embodiment of this utility model, the specific push-back section 2 includes a housing 21, a hydraulic balancing part 3 installed in the housing 21 to maintain internal and external pressure balance, a power part 4 to provide power output, a lead screw part 5 to convert the power output of the power part 4 into axial thrust, a measuring push rod part 6 to transmit the power of the lead screw part 5, and a push-back part 8 that is independently installed and opens and closes according to the action of the measuring push rod part 6.

[0051] The hydraulic balancing unit 3 can be directly installed inside the housing 21, or it can be a separate drive housing 31 connected to the housing 21. Using a separate drive housing 31 makes it easier to disassemble the entire push-button section 2. Taking the separate drive housing 31 as an example, a balancing chamber 32 for receiving external mud, an isolation piston 33, and a spring 34 are provided inside the drive housing 31. Under the control of the spring 34, the isolation piston 33 divides the balancing chamber 32 into a mud chamber and a hydraulic oil chamber. The mud chamber draws in mud according to the downhole pressure, which in turn pushes the isolation piston 33 to squeeze the hydraulic oil chamber on the other side, thereby keeping the internal and external pressures balanced.

[0052] The power unit 4 includes a motor 41 arranged sequentially inside the housing 21, a motor transmission rod and a torque limiter 42 connected sequentially to the motor shaft of the motor 41; when the motor 41 is working, it outputs rotational power through the torque limiter 42.

[0053] The lead screw section 5 includes a lead screw 51 installed inside the housing 21 and connected to the torque limiter 42, a lead screw sleeve 52 sleeved on the lead screw 51, and a push tube 53 connected to the lead screw sleeve 52. The lead screw 51 rotates under the action of rotational power and pushes the lead screw sleeve 52 to make axial linear motion inside the housing 21, thereby pushing the push tube 53 to move axially.

[0054] The measuring push rod section 6 includes a push rod cylinder 61 installed inside the housing 21, four to six push rods 62 symmetrically distributed inside the push rod cylinder 61, each push rod 62 having a disc assembly 63 fitted on it, and a measuring arm 64 connected to each of the four to six push rods 62. The push tube 53 pushes the disc assembly 63 on each push rod 62 to move each push rod 62 axially. Each push rod 62 moves a corresponding distance according to the elastic feedback of the disc assembly 63. The measuring arm 64 calculates the corresponding data based on the distance moved by each push rod 62, and then applies the corresponding angle formula to determine the opening angle of the push arm corresponding to each push rod 62. After integration, the well diameter at the current position can be calculated based on the opening angle of each push arm.

[0055] The detailed structure and connection relationship of each component in the aforementioned push-fit section 2 are not within the scope of this improvement. Therefore, please refer to the description in application number 202422866356.5 for details. The improved push-fit section of this solution will be described in detail below.

[0056] like Figure 6 As shown, the pushing part 8 includes a pushing base 81 and four to six pushing arms 82 evenly distributed around the circumference of the pushing base 81 (the attached diagram of this scheme only shows a schematic of four arms, but the structure of six arms is the same). Each pushing arm 82 includes a main arm 821, a secondary arm 822, a main arm support rod 823, a secondary arm support rod 824, and a pushing plate 825. One end of the main arm 821 and the main arm support rod 823 are rotatably connected to the pushing base 81, while one end of the secondary arm 822 is slidably connected to the pushing base 81. The other ends of the main boom 821 and the auxiliary boom 822 are respectively hinged to the two ends of the push plate 825, while the other end of the main boom support rod 823 is connected to the middle of the push plate 825. After connection, the main boom 821 and the auxiliary boom 822 are positioned opposite each other and form a trapezoidal shape when opened. The main boom support rod 823 is installed within the range formed by the main boom 821 and the auxiliary boom 822 and is parallel to the main boom 821. A sliding groove 826 is provided on the auxiliary boom 822. One end of the auxiliary boom support rod 824 is installed in the sliding groove 826 through a pin, and the other end is hinged to the push base 81 on the outside of the auxiliary boom 822.

[0057] One end of the main boom 821 connected to the push base 81 is connected to the push rod 62 via the two-section rod 621. When the push rod 62 pushes the two-section rod 621 to move, it will push the main boom 821 to open and rotate around the connection point with the push base 81. The push plate 825 will drive the main boom support rod 823 and the auxiliary boom 822 to rotate and open simultaneously. The opening of the auxiliary boom 822 will drive one end of the auxiliary boom support rod 824 located in the sliding groove 826 to move within the sliding groove 826, thereby driving the auxiliary boom support rod 824 to rotate around the connection point with the push base 81. When the push plate 825 contacts the well wall, the main boom 821 stops rotating.

[0058] In this embodiment, the extended push arm 82 forms a trapezoid, so that the push section 2 will not get stuck on the well wall whether it is moving up or down in the well. This avoids the problem in the prior art where the push arm 82 adopts a single rod structure and can only move in one direction after it is extended, but is easily stuck in the well wall when moving in the opposite direction.

[0059] The structure of main boom support rod 823 and auxiliary boom support rod 824 can enhance the strength of the push arm 82 itself, and at the same time, it can keep the push arm 82 stable during travel measurement, thereby improving measurement accuracy.

[0060] To facilitate the accommodation of the push-back arms 82, a receiving groove 811 is provided on the push-back base 81 to accommodate each push-back arm 82. An axial auxiliary arm slide groove 812 is provided within the receiving groove 811. The connecting end of the auxiliary arm 822 to the push-back base 81 is installed in the auxiliary arm slide groove 812 via a pin. The auxiliary arm slide groove 812 can limit the movement distance of the auxiliary arm 822, i.e., the opening angle, thereby indirectly controlling the angle opening range of the main arm 821.

[0061] In one embodiment of this utility model, a limiting block 83 is installed in the receiving groove 811 on the outer side of the connection end between the main arm 821 and the push base 81 to limit the opening angle of the main arm 821. In this design, the push arm 82 is for measuring the well diameter and does not need to provide support. Therefore, if a push arm 82 is excessively opened, it may sink into the well wall, leading to measurement errors. Therefore, the limiting block 83 is needed to limit the opening angle range of each main arm to ensure that each push arm 82 contacts the well wall, thereby obtaining accurate measurement results.

[0062] To reduce the volume of the push arm 82 after it is retracted, a storage groove (not shown in the figure) is provided on the side of the auxiliary arm support rod 824 opposite to the auxiliary arm 822 to accommodate the auxiliary arm 822. When the push arm 82 is fully retracted into the storage groove 811, the auxiliary arm 822 can be inserted into the auxiliary arm support rod 824 (i.e., the auxiliary arm support rod 824 is fitted onto the auxiliary arm 822), thereby reducing the space occupied and leaving enough space for installing multiple push arms 82.

[0063] like Figure 7 As shown, in one embodiment of the present invention, a connector 9 is installed between the hydraulic balance part 3 and the power part 4 to connect the two. The connector 9 includes a left housing 91 that is plugged into the hydraulic balance part 3 via a key, a right housing 92 that is movably plugged into the power part 4, and a multi-core plug 93 with multiple pins at both ends of the axial direction. A third multi-hole socket 94 that is plugged into the pins of the multi-core plug 93 is installed in the left housing 91 and the right housing 92 respectively.

[0064] This solution allows the hydraulic balance unit 3 to be set as an independent component relative to the entire push-fit sub-section 2. It is connected externally by clamps and internally by a multi-core plug 93 to achieve signal connection with the push-fit sub-section 2. This simplifies the size of the entire push-fit sub-section 2 and makes it easier to disassemble and maintain internal components. It avoids the problems of the existing technology, which sets the hydraulic balance unit 3 and the entire push-fit sub-section 2 as one unit, resulting in difficulties in the internal planning of the housing 21 and complicated cable connection.

[0065] To reduce the hard compression on the multi-pin plug 93, a pressure relief disc 95 is installed between the right housing 92 and the power unit 4. The pressure relief disc 95 can alleviate the impact force when the hydraulic balance unit 3 and the push-button section 2 are connected, and prevent damage to the connection between the pin and the third multi-hole socket 94.

[0066] Therefore, those skilled in the art should recognize that although many exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A high-temperature, high-pressure, small-diameter wellbore gauge, comprising an upper connector, a push-off sub, and a lower connector connected in sequence, characterized in that, The upper connector includes a first connecting housing and a multi-core housing that are connected to each other. The other end of the multi-core housing is connected to a push-back short section. A first multi-core socket is installed inside the multi-core housing. The outer surface of the first multi-core socket is provided with a sealing section and a support section with a sealing ring. The diameter of the support section is larger than the diameter of the sealing section. Pin seats are provided at both ends of the first multi-core socket along the axial direction. A first convex ring is provided on the inner surface of the multi-core housing that contacts the sealing section and blocks the support section. The lower connector includes a second connecting housing connected to the push-back short section, and a second multi-core socket with the same structure as the first multi-core socket installed inside the second connecting housing. A second protruding ring with the same structure as the first protruding ring is provided on the inner surface of the second connecting housing. The first multi-core socket has pins at both ends that are connected to the first connecting housing and the multi-hole socket in the push-back section, respectively. The second multi-core socket has pins at one end that are connected to the multi-hole socket in the push-back section, and the other end that is connected to the multi-hole socket in the second connecting housing.

2. The high-temperature, high-pressure, small-diameter wellbore gauge according to claim 1, characterized in that, The first multi-core housing and the second multi-core housing have the same interface as the push-fit short section, and the first multi-core housing and the second multi-core housing can be interchanged in their installation positions relative to the push-fit short section.

3. The high-temperature, high-pressure, small-diameter well caliper according to claim 1, characterized in that, A circuit base is installed inside the connecting housing. The outer surface of the circuit base is surrounded by three planes, and an axial channel is provided inside. Each plane has an opening at both ends of its axial direction that communicates with the axial channel.

4. The high-temperature, high-pressure, small-diameter well caliper according to claim 3, characterized in that, One end of the circuit base is provided with a tube for inserting the multi-hole socket, and the other end is provided with a baffle that contacts the retaining ring inside the connecting housing. The tube and the baffle are respectively connected to the axial channel.

5. The high-temperature, high-pressure, small-diameter wellbore gauge according to claim 1, characterized in that, The push-fit short section includes a hydraulic balancing part to maintain internal and external pressure balance, a power part to provide power output, a lead screw part to convert rotational power into linear power, a measuring push part that outputs thrust using a push rod, and a push-fit part controlled by the push rod, wherein: The push-back part includes a push-back base and four push-back arms evenly distributed around the circumference of the push-back base. Each push-back arm includes a main arm, a secondary arm, a main arm support rod, a secondary arm support rod, and a push-back plate. One end of the main arm, the secondary arm, and the main arm support rod are rotatably connected to the push-back base, and the other end is hinged to the push-back plate. After connection, the main arm and the secondary arm are positioned opposite each other and form a trapezoidal shape when opened. The main arm support rod is installed within the range formed by the main arm and the secondary arm and is parallel to the main arm. A sliding groove is provided on the secondary arm. One end of the secondary arm support rod is installed in the sliding groove through a pin, and the other end is hinged to the push-back base outside the secondary arm.

6. The high-temperature, high-pressure, small-diameter wellbore gauge according to claim 5, characterized in that, A receiving groove for accommodating the pushing arm is provided on the pushing base, and an axial auxiliary arm slide groove is provided in the receiving groove. The connecting end of the auxiliary arm and the pushing base is installed in the auxiliary arm slide groove by a pin.

7. The high-temperature, high-pressure, small-diameter wellbore gauge according to claim 5, characterized in that, A limiting block is installed in the receiving groove outside the connection end between the main arm and the push base to restrict the opening angle of the main arm.

8. A high-temperature, high-pressure, small-diameter wellbore gauge according to claim 5, characterized in that, On the side of the auxiliary arm support rod opposite to the auxiliary arm, there is a storage groove for accommodating the auxiliary arm.

9. A high-temperature, high-pressure, small-diameter wellbore gauge according to claim 5, characterized in that, A connector is installed between the hydraulic balancing unit and the power unit to connect the two. The connector includes a left housing that is plugged into the hydraulic balancing unit via a key, a right housing that is movably plugged into the power unit, and a multi-pin plug. A third multi-hole socket that is plugged into the multi-pin plug is installed in the left housing and the right housing respectively.

10. A high-temperature, high-pressure, small-diameter well caliper according to claim 9, characterized in that, A decompression disc is installed between the right housing and the power unit.

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