Small-diameter six-arm caliper

Abstract

The utility model provides a small-diameter six-arm caliper which comprises an upper connector used for connecting adjacent short sections, a balance part used for keeping balance of internal and external pressure, a driving part used for providing power, a lead screw part used for converting rotating power into linear motion, a pushing part used for outputting pushing force and a measuring part used for synchronously opening and closing measuring arms according to the magnitude of the pushing force, the upper connector comprises an upper connector shell, and a multi-core plug and a board clamping frame for installing a circuit board are installed in the upper connector shell. According to the utility model, the circuit control part is separated from the controlled motor part, so that the space occupied by the driving part is reduced, and the radial arrangement is reduced by connecting all parts step by step, so that the diameter of the whole caliper is reduced, and finally, the purpose of measuring the small-diameter hole diameter of 3.6 inches is achieved.

Description

Technical Field

[0001] The utility model relates to the field of petroleum exploration, in particular to a six-arm caliper which can be used for measuring the calipers of small-diameter and large-diameter oil wells at the same time. Background Art

[0002] In the field of oil exploration, the well diameter formed during the drilling process is not a constant diameter. This diameter change will appear different due to different formation materials, different drill bits or different drilling methods.

[0003] In addition, after the well is drilled, the well diameter at different depths will change due to geological changes, such as tilting, collapse, shrinkage, etc. In order to facilitate subsequent work, it is necessary to understand the well diameter changes in real time.

[0004] Most existing calipers are used to measure the diameter of large-diameter oil wells (such as more than 4.5 inches). For example, the patent with application number: 202322095181.8 discloses a four-arm caliper in which each arm can independently push and lean. It uses multiple motors to control a measuring rod to measure the diameter of the oil well. Although the adaptability of measurement is improved according to the changes in different well diameters, in terms of volume, it can only measure the diameter of large-diameter oil wells. Its structural setting cannot be applied to the diameter measurement of small-diameter oil wells (such as about 3.6 inches).

[0005] Measuring small-diameter oil wells is not simply a matter of reducing the size of existing large-diameter oil well measurement tools. It is necessary to consider the pressure conditions of the entire measuring equipment, the internal wiring direction, the connection between the various components, and subsequent maintenance. Utility Model Content

[0006] The utility model aims to provide a six-arm caliper which can be used for measuring the calipers of small-diameter and large-diameter oil wells at the same time.

[0007] Specifically, the utility model provides a small-diameter six-arm caliper, comprising an upper joint for connecting adjacent short sections, a balancing part for maintaining internal and external pressure balance, a driving part for providing power, a screw part for converting rotary power into linear motion, a pushing part for outputting thrust, a measuring part for synchronously opening and closing the measuring arms according to the thrust, and a lower joint for connecting adjacent short sections.

[0008] The upper connector includes an upper connector housing, in which a multi-core plug and a board rack for mounting a circuit board are installed;

[0009] The balancing part includes a drive housing, which is connected to the upper joint housing through a transfer joint with a pressure-bearing socket A. The drive housing is provided with a balancing chamber for receiving external mud, a delivery pipe A for conveying cables and hydraulic oil, and an isolation piston and spring sleeved on the delivery pipe A.

[0010] The driving part includes a motor sequentially arranged in a driving housing, a motor transmission rod and a torque limiter sequentially connected to the motor shaft;

[0011] The screw rod part includes a screw rod installed in the drive housing and connected to the torque limiter, a screw rod sleeve sleeved on the screw rod, and a push tube connected to the screw rod sleeve;

[0012] The push part includes a push rod cylinder installed in the drive housing, six push rods symmetrically distributed in the push rod cylinder, and a delivery pipe B located inside the push rod cylinder and connected to the push tube;

[0013] The measuring unit includes measuring arms connected to six push rods, a measuring cylinder that accommodates the measuring arms and is connected to the drive housing, and a delivery pipe C located inside the measuring cylinder and connected to the delivery pipe B.

[0014] The lower joint includes a lower joint housing connected to the measuring tube and a pressure-bearing socket B installed in the lower joint housing.

[0015] In one embodiment of the present invention, the board bracket includes a mounting tube A and a mounting tube B, a frame connecting the mounting tube A and the mounting tube B, a spring installed on the outer surface of the mounting tube A, and a pressure reducing gasket is provided at the end of the mounting tube B that contacts the pressure-bearing socket A.

[0016] In one embodiment of the present invention, an axial sliding groove A is opened on the outer surface of the multi-core plug. A pin shaft A inserted into the sliding groove A is installed on the upper joint housing; an axial sliding groove B is provided at one end of the multi-core plug for inserting the mounting tube A, a pin shaft B inserted into the sliding groove B is provided on the mounting tube A, and an axial limit key is provided on the outer circumference of the mounting tube B.

[0017] In one embodiment of the present invention, the screw rod portion is installed in a screw rod housing, three axial sliding grooves C are distributed on the screw rod housing, three sliding blocks are installed on the screw rod sleeve and are respectively inserted into the three sliding grooves C, and bolts are installed on the sliding blocks to fix the screw rod sleeve and the push tube together.

[0018] In one embodiment of the present utility model, a ranging tube is installed on the outer surface of the push tube, and a ranging groove is provided on the circumference of the outer surface of the ranging tube. A displacement sensor for measuring the moving distance of each push rod and a thrust sensor for measuring the thrust of the push tube are installed in the ranging groove. The displacement sensor and the thrust sensor are clamped and fixed in the ranging groove by multiple arc-shaped clamping rings, and a groove is provided on the inner surface of the clamping ring to fit the outer surface of the displacement sensor and the thrust sensor.

[0019] In one embodiment of the present invention, a hollow channel is provided inside the push tube, and a baffle with positioning holes is provided near one end of the push rod. The number and positions of the positioning holes on the baffle correspond to the number and positions of the push rods, and a groove for the left end of the push rod to enter is provided on the left side of the baffle of the push tube.

[0020] In one embodiment of the present invention, the outer surface of the measuring cylinder is provided with measuring grooves for accommodating the six measuring arms respectively, the push rod is connected to the measuring arm pin through a sealing section and two connecting rods, one end of the measuring arm is installed in the measuring groove through a pin shaft, and a protruding connecting block is provided at the connecting end, the two connecting rods are pin-connected to the connecting block, and a connecting rod groove for accommodating the two connecting rods is provided in the measuring groove.

[0021] In one embodiment of the present invention, the measuring part also includes an extension rod connected to each of the measuring arms respectively, one end of the extension rod is connected to the outer surface pin of the measuring cylinder, a connecting strip with a sliding groove D is provided on the rod body of the extension rod, the support end of the measuring arm in contact with the well wall is installed on the connecting strip through a pin inserted into the sliding groove D, and a fixed head is installed on the support end of the measuring arm, the fixed head includes a fixed head A with a pin connected to the extension rod, and a fixed head B without a pin installed when the measuring arm works independently.

[0022] In one embodiment of the present invention, an extension rod positioning sleeve is fixed at both ends of the outer surface of the measuring tube, and each extension rod positioning sleeve is provided with an open groove corresponding to the positions of the two ends of each extension rod after being folded, and the two extension rod positioning sleeves are installed in a manner that the openings of the open grooves are opposite to each other.

[0023] In one embodiment of the present invention, the push rod tube and the measuring tube are plugged into each other, and a positioning key is installed at the plug-in point to prevent radial rotation. One end of the delivery tube B is threadedly connected to the measuring tube and then connected to the delivery tube C.

[0024] The utility model reduces the space occupied by the driving part by separating the circuit control part from the controlled motor part, and reduces the radial arrangement by connecting the components step by step, thereby reducing the diameter of the entire caliper, and ultimately achieving the purpose of measuring a small diameter well of 3.6 inches. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural diagram of the utility model;

[0026] Figure 2 This is a schematic structural diagram of a measuring arm in one embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the internal structure of the upper joint in one embodiment of the present invention;

[0028] Figure 4 This is a structural diagram of the screw rod portion and the pushing portion in one embodiment of the present invention;

[0029] Figure 5 This is a schematic structural diagram of a fixed head in one embodiment of the present utility model;

[0030] Figure 6 This is a schematic diagram of another fixed head structure in one embodiment of the present invention. DETAILED DESCRIPTION

[0031] The structure and operation of this solution are further described below through specific implementations and accompanying drawings. 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 from hydraulic oil and / or mud penetration are equipped with corresponding static or dynamic sealing strips, which will not be repeated here.

[0032] like Figure 1 As shown, this embodiment discloses a small-diameter six-arm caliper, including an upper joint 1 for connecting adjacent short sections, a balancing part 2 for maintaining internal and external pressure balance, a driving part 3 for providing power, a screw part 4 for converting rotational power into linear motion, a pushing part 5 for outputting thrust, a measuring part 6 for synchronously opening and closing the measuring arm according to the thrust, and a lower joint 7 for connecting adjacent short sections; the above-mentioned components are connected together in sequence to form the entire caliper, and the composition of each component and the method of mutual connection are described in detail below.

[0033] The upper connector 1 is used to connect adjacent short sections that need to be connected. That is, the caliper of this solution can be connected to other short sections through the upper connector 1 and the lower connector 7 and then lowered into the well at the same time, so as to complete multiple measurement tasks in one go. The specific upper connector 1 includes an upper connector housing 11, in which a multi-core plug 12 and a board holder 13 for mounting a circuit board are installed; the multi-core plug 12 can transport cables and hydraulic oil to the adjacent short sections through connection. Since this solution involves small-diameter oil wells, in order to reduce the diameter of the entire caliper, the control circuit of the entire caliper is separated and installed separately, and then connected to the controlled motor, sensor and other components through internal cables. The circuit board is installed on the board holder 13.

[0034] The balancing part 2 is used to keep the internal pressure of the caliper balanced with the downhole pressure, and includes a drive housing 21. The left end of the drive housing 21 is connected to the upper joint housing 11 through a transfer joint A22 with a pressure-bearing socket A23. A mud chamber 24 communicating with the outside is arranged in the drive housing 21, a delivery pipe A25 installed on the axis line for conveying cables and hydraulic oil, and an isolation piston 26 and a spring 27 sleeved on the delivery pipe A25; the outer circumferential surface of the isolation piston 26 is in sliding contact with the inner surface of the drive housing 21, and the inner hole is in sliding contact with the outer surface of the delivery pipe A25. One end of the spring 27 is fixed to the right end of the delivery pipe A25, and the other end is fixed to the isolation piston 26. The diameter of the tube body of the delivery pipe A25 where the spring 27 is installed is larger than the diameter of the tube body where the isolation piston 26 is installed. When the isolation piston 26 moves to the right end, it will eventually be blocked by the raised step, thereby preventing the isolation piston 26 from excessively squeezing the spring 27. The two ends of the spring 27 are fixed to prevent the isolation piston 26 from moving to the mud hole 241, which would cause the mud and hydraulic oil to penetrate each other.

[0035] When the caliper is lowered into the well, the mud will enter the mud chamber 24 on the left side of the balancing part 2 through the mud hole 241 of the drive housing 21. As the downhole pressure increases, the mud in the mud chamber 24 will gradually push the isolation piston 26 to squeeze the spring 27 to move to the right side of the balancing part 2, while squeezing the hydraulic oil on the right side until the isolation piston 26 is blocked by the step on the delivery pipe A25, and finally the hydraulic oil pressure inside the caliper and the mud pressure in the mud chamber 24 on the left side are balanced.

[0036] The drive unit 3 is mounted in the drive housing 21 and is used to provide power. The drive unit 3 includes a motor 31 mounted on a motor base 32, two motor transmission rods 33 connected to the motor output shaft, and a torque limiter 34.

[0037] The right end of the conveying pipe A25 is fixedly connected to the motor base 32 by bolts. The motor 31 is installed in the motor base 32 and the motor output shaft faces to the right. The two motor transmission rods 33 are connected in sequence to reduce the speed of the motor output and maintain the stability of the output power. The right end of the motor transmission rod 33 on the right is connected to the torque limiter 34. The right end of the torque limiter 34 is plugged into the left end of the following screw rod 41. The torque limiter 34 is used to release the torque when the motor transmission rod 33 rotates in a certain direction to the limit, so as to prevent the screw rod part 4 from being damaged by hard rotation.

[0038] The screw part 4 is used to convert the rotational power output by the motor 31 into a driving power outputted in a linear manner, and includes a screw 41 installed in the drive housing 21, a screw sleeve 42 sleeved on the screw 41, and a push tube 43 connected to the screw sleeve 42; the left end of the screw 41 is plugged into the output end of the torque limiter 34, and it rotates with the torque limiter 34. The left end of the screw sleeve 42 is screwed onto the screw 41 through a thread, and the right end is open and does not contact the outer surface of the screw 41. The left end of the push tube 43 is an open end, and the screw 41 is accommodated inside the opening so that the screw 41 can move into the opening. The right end of the screw sleeve 42 is sleeved on the outer surface of the left end of the push tube 43 and is fixed thereto.

[0039] A hollow channel is provided inside the push tube 43, and a baffle 44 with positioning holes is provided at the right end. The number and position of the positioning holes on the baffle 44 correspond to the number and position of the push rods described below. A groove 431 is provided on the left side of the baffle 44 of the push tube 43 for the left end of the push rod to enter.

[0040] When the screw rod 41 rotates, it drives the screw rod sleeve 42 to rotate. Under the action of the positioning key, the screw rod sleeve 42 can only move axially and cannot rotate radially, thereby pushing the push tube 43 to move axially.

[0041] The pushing part 5 includes a push rod tube 51 installed in the drive housing 21, and six push rod holes 511 are provided in the push rod tube 51. A push rod 52 is installed in each push rod hole. A disc spring group 53 is sleeved on the outer surface of the push rod 52, and a retaining ring 54 is provided on the outer surface of the right end of the push rod 52 to prevent the disc spring group 53 from escaping. The diameter of the retaining ring 54 is larger than the diameter of the push rod hole 511, so that the disc spring group 53 cannot pass through the push rod hole 511. A fixing bolt 55 is screwed on the left end of the push rod 52 to prevent the disc spring group 53 from escaping. A transmission cable connected to the push tube 43 and a hydraulic oil delivery pipe B56 are provided on the axial center line of the push rod tube 51.

[0042] After the left end of the push rod 52 extends into the positioning hole on the baffle 44 of the push tube 43, the fixing bolt 55 is installed to prevent it from axially detaching. At the same time, the push rod 52 always applies a pulling force to the baffle 44 under the elastic force of the disc spring assembly 53.

[0043] When the screw 41 rotates, the screw sleeve 42 drives the push tube 43 to move axially. The moving push tube 43 squeezes the disc spring group 53 through the baffle 44, thereby driving the push rod 52 to extend from the push rod hole 511 of the push rod tube 51 until the retaining ring 54 on the push rod 52 is blocked by the push rod hole 511, and the measuring arm 61 connected to the right end of the push rod 52 can rotate within the moving range of the push rod 52, and the corresponding well diameter can be measured according to its opening angle or the moving distance of the push rod 52.

[0044] like Figure 2 As shown, the measuring part 6 includes a measuring arm 61 connected to the six push rods 52 respectively, a measuring cylinder 62 for accommodating the measuring arm 61, and a delivery pipe C63 located inside the measuring cylinder 62 for conveying cables and hydraulic oil; the measuring cylinder 62 serves as a mounting and accommodating base for the measuring arm 61; one end of the measuring arm 61 is connected to the axis of the measuring cylinder 62, and the other end is a free end. After installation, the measuring arm 61 rotates within a certain range with the installation end as the base point under the action of the push rod 52. During the rotation, the free end of the measuring arm 61 will contact the well wall. At this time, the well diameter size at the current position can be calculated by calculating the opening angle of each measuring arm 61 or the displacement of each push rod 52.

[0045] The lower joint 7 is used to output the cables and hydraulic oil transported through the delivery pipe B56 and the delivery pipe C63, and includes a lower joint shell 71. The lower joint shell 71 is connected to the measuring cylinder 62 through a lower transfer joint 72 equipped with a pressure socket B73; after connection, the adjacent short sections can be directly plugged into the pressure socket B73 in the lower joint shell 71, thereby realizing the connection between the cables and the hydraulic oil.

[0046] The working process of the above structure is described below:

[0047] The circuit board installed on the board holder 13 sends an operating instruction to the motor 31 through the pressure-bearing socket A23. After the motor 31 rotates, the output speed is reduced through the motor transmission rod 33, and the screw rod 41 is driven to rotate through the torque limiter 34. After the screw rod 41 rotates, it drives the screw rod sleeve 42 to make a linear motion, thereby pushing the push tube 43 to move. The push tube 43 pushes the push rod 52 located in the push rod tube 51 to move through the baffle 44. The push rod 52 pushes the connected measuring arm 61 to rotate under the elastic force of the disc spring group 53. The rotated measuring arm 61 stops after encountering the well wall. The circuit board can calculate the well diameter value at the current position according to the opening angle of each measuring arm 61 or the displacement of each push rod 52.

[0048] After the current position measurement is completed, the control motor 31 is reversed and the screw sleeve 42 can be used to retract the push tube 43, and then the push rod 52 pulls the measuring arm 61 back under the elastic force of the disc spring group 53. Finally, the measuring arm 61 is attached to the measuring tube 62 and then enters the next measurement position. Repeating the above process can complete the wellbore measurement of the entire oil well.

[0049] During the measurement process, mud will automatically enter the balancing part 2, and as the downhole pressure increases, the entering mud will push the isolation piston 26 to move to the right to squeeze the hydraulic oil on the right side. Finally, the downhole pressure will reach a balance with the internal hydraulic oil under the regulation of the isolation piston 26 to prevent the inside of the caliper from being damaged by external pressure.

[0050] In this solution, the cables and hydraulic oil are transported as follows:

[0051] The cables and hydraulic oil connected to the multi-core plug 12 in the upper connector 1 pass through the board holder 13, are connected to the left end of the pressure socket A23, and then enter the delivery pipe A25 located in the balancing part 2 through the right end of the pressure socket A23. The cables and hydraulic oil output from the right end of the delivery pipe A25 pass through the channel between the motor seat 32 and the drive housing 21, and then enter the channel between the screw part 4 and the drive housing 21, enter the delivery pipe B56 of the pushing part 5, and then enter the delivery pipe C63 inside the measuring cylinder 62, and are connected to the left end of the pressure socket B73 in the lower connector 7.

[0052] This embodiment reduces the space occupied by the drive unit by separating the circuit control portion from the controlled motor portion, and reduces the radial layout by gradually connecting the components, thereby reducing the diameter of the entire caliper, ultimately achieving the purpose of measuring a small diameter well of 3.6 inches.

[0053] like Figure 3 As shown, in one embodiment of the present invention, the board rack 13 includes two cylindrical mounting cylinders A132 and a mounting cylinder B133, and the mounting cylinder A132 and the mounting cylinder B133 are connected by a plate-shaped frame 131. The circuit board is installed on the frame 131. The mounting cylinder A132 and the mounting cylinder B133 serve as fixed objects and channels for cables to pass through. The mounting cylinder A132 is plugged into the multi-core plug 12, and a spring 134 is installed on the outer surface of the mounting cylinder A132. A pressure reducing gasket 135 is provided at the end of the mounting cylinder B133 that contacts the pressure-bearing socket A23.

[0054] The mounting tube A132 and the multi-core socket 12 are movably connected, and the spring 134 acts as a buffer. When the multi-core plug 12 is plugged into the adjacent short section, the pressed multi-core plug 12 will squeeze the spring 134 and slide on the outer surface of the mounting tube A132, while the board holder 13 can remain unaffected.

[0055] The pressure relief washer 135 can prevent the mounting cylinder B133 from directly colliding with the pressure-bearing socket A23 and provide a buffer when the entire board rack 13 is subjected to external force.

[0056] In one embodiment of the present invention, an axial sliding groove A121 is opened on the outer surface of the multi-core plug 12. A pin A111 inserted into the sliding groove A121 is installed on the upper connector housing 11. This structure enables the multi-core plug 12 to move inward when squeezed by external force and prevents radial rotation.

[0057] Furthermore, an axial sliding groove B122 is provided at one end of the multi-core plug 12 for plugging into the mounting cylinder A132, and a pin shaft B136 inserted into the sliding groove B122 is provided on the mounting cylinder A132. When the multi-core plug 12 is squeezed, it can move axially relative to the board frame 13 without colliding with the plugged-in mounting cylinder A132. The pin shaft B136 enables the multi-core plug 12 to move axially only within the range of the sliding groove B122, but not radially.

[0058] Furthermore, an axially protruding limit key 137 is provided on the outer circumference of the mounting cylinder B133, and a positioning groove 112 for inserting the limit key 137 is provided at the corresponding position of the upper joint shell 11. This structure can further enhance the anti-radial rotation effect of the board holder 13 without affecting the axial plug-in.

[0059] like Figure 4 As shown, in one embodiment of the present utility model, in order to prevent radial rotation of the screw sleeve 42, the screw part 4 also includes a screw housing 45, the outer surface of the screw housing 45 is in contact with the inner surface of the drive housing 21, and the inner surface is in contact with the outer surface of the screw sleeve 42, and three axial sliding grooves C47 are provided on the screw housing 45, and three sliding blocks 46 are installed on the screw sleeve 42, which are respectively inserted into the three sliding grooves C47, and bolts are installed on the sliding blocks 46 to fix the screw sleeve 42 and the push tube 43 together.

[0060] When the screw 41 rotates, the screw sleeve 42, which is threaded onto the screw 41, is restrained by three sliding blocks 46 and cannot rotate radially, but can move axially along the sliding grooves C47. The use of three sliding grooves C47 stabilizes the axial movement of the screw sleeve 42. Furthermore, the outer surface of the screw housing 45 is provided with an axial planar channel (not shown) for the passage of cables and hydraulic oil passing therethrough. The three sliding grooves C47 are evenly distributed within a 180-degree circumference of the screw housing 45.

[0061] In one embodiment of the present invention, in order to facilitate the measurement of the moving distance of the push rod 52, a ranging tube 48 is installed on the outer surface of the push tube 43, and a ranging groove 481 is provided on the circumference of the outer surface of the ranging tube 48. A displacement sensor 482 for measuring the moving distance of each push rod 52 and a thrust sensor 483 for measuring the thrust of the push tube 43 are installed in the ranging groove 481. The displacement sensor 482 and the thrust sensor 483 are clamped and fixed in the ranging groove 481 by multiple arc-shaped retaining rings 49, and a groove is provided on the inner surface of the retaining ring 49 to fit the outer surface of the displacement sensor 482 and the thrust sensor 483.

[0062] When pushed by baffle 44, push rod 52 extends from its positioning hole and contacts displacement sensor 481. The distance displacement sensor 481 is pushed is used to calculate the current rotation angle of measuring arm 61, and thus the wellbore diameter at that location. Similarly, thrust sensor 482, connected to baffle 44, measures the axial thrust of baffle 44 as it moves, thereby providing a corresponding power value.

[0063] In one embodiment of the present invention, to facilitate the accommodation of the measuring arms 61, the outer surface of the measuring cylinder 62 is provided with measuring grooves 621, each accommodating six measuring arms 61. To facilitate sealing of the push rod 52 and prevent leakage of internal hydraulic oil from the measuring grooves 621, a sealing section 521 is threadedly connected to the right end of the push rod 52, and a sealing ring 522 is installed on the sealing section 521. To facilitate the rotation of the measuring arms 61, the push rod 52 is connected to a second connecting rod 523 through the sealing section 521, and then pinned to the measuring arms 61. In this structure, one end of the measuring arm 61 is mounted in the measuring groove 621 via a pin, and a protruding connecting block 622 is provided at the connecting end. The second connecting rod 523 is pinned to the connecting block 622. At the same time, a connecting rod groove 623 is provided in the measuring groove 621 to accommodate the second connecting rod 523.

[0064] When the push rod 52 is pushed, the connecting block 622 is rotated via the second connecting rod 523. The connecting block 622 then rotates the measuring arm 61 using the connection point between the measuring arm 61 and the measuring slot 621 as a fulcrum. This structure minimizes the number of connections while maximizing the rotation range of the measuring arm 61.

[0065] During installation and maintenance, the sealing section 521 can be directly unscrewed from the push rod 52 to replace or maintain the sealing ring 522. At this time, the push rod 52 still blocks the push rod hole to prevent the hydraulic oil from leaking.

[0066] In one embodiment of the present invention, in order to enable the caliper to adapt to the measurement of large-diameter wells, the measuring unit 6 also includes an extension rod 64 connected to each measuring arm 61, one end of the extension rod 64 is pin-connected to the outer surface of the measuring tube 62, and a connecting bar 641 with a sliding groove D642 is provided on the rod body of the extension rod 64. The contact end of the measuring arm 61 that contacts the well wall is connected to the connecting bar 641 through a pin inserted into the sliding groove D642. A fixed head 65 is installed on the contact end of the measuring arm 61. Figure 5 、 6 As shown, the fixed head 65 includes a fixed head A651 with a pin connected to the extension rod 64, and a fixed head B652 without a pin installed when the measuring arm 61 works independently.

[0067] Extension rod 64 is an optional component. When the diameter of the oil well to be measured is larger than the diameter of the extended measuring arm 61, an extension rod 64 of the corresponding length can be installed. The opening angle of extension rod 64 is controlled by measuring arm 61. Therefore, even with extension rod 64 installed, the diameter of the larger oil well can still be calculated by measuring the angle of the extended measuring arm 61. Fixed head A651 or fixed head B652 is selected depending on whether extension rod 64 is installed.

[0068] To facilitate storage of the retracted extension rod 64, an extension rod positioning sleeve 66 is fixed to each end of the outer surface of the measuring tube 62. Each extension rod positioning sleeve 66 has an opening corresponding to the position of the two ends of the extension rod 64 after retracting. The two extension rod positioning sleeves 66 are installed with the openings of the openings facing each other. When the measuring arm 61 retracts the extension rod 64, the measuring arm 61 enters the measuring slot 621, while the ends of the extension rod 64 snap into the openings of the extension rod positioning sleeve 666, thereby reducing friction with the wellbore wall.

[0069] In one embodiment of the present invention, the push rod tube 51 and the measuring tube 62 are installed together by plugging into each other, and a positioning key is installed at the plug-in point to prevent radial rotation. At the same time, the right end of the delivery tube B56 in the push rod tube 51 is threadedly connected to the delivery tube C63 in the measuring tube 62 through a thread.

[0070] Since the components inside the drive housing 21 all work in an axially moving manner, the components can be connected by plugging. However, plugging cannot guarantee that the two connected components will not separate. If the two components are made into one piece, the manufacturing difficulty is increased. Therefore, after the push rod tube 51 and the measuring tube 62 are plugged in, the present solution uses a positioning key to prevent the two from rotating radially relative to each other, and then screws the two together through the delivery tube B56 to prevent axial separation. This not only saves installation steps, but also simplifies the connection, making it convenient for later maintenance and disassembly.

[0071] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications consistent with the principles of the present invention can be directly determined or deduced from the contents disclosed herein without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all such other variations or modifications.

Claims

1. A small-diameter six-arm caliper, comprising an upper joint for connecting adjacent short sections, a balancing section for maintaining internal and external pressure balance, a driving section for providing power, a screw section for converting rotational power into linear motion, a pushing section for outputting thrust, a measuring section for synchronously opening and closing the measuring arms according to the magnitude of the thrust, and a lower joint for connecting adjacent short sections, characterized in that: The upper connector includes an upper connector housing, in which a multi-core plug and a board rack for mounting a circuit board are installed; The balancing part includes a drive housing, which is connected to the upper joint housing through a transfer joint with a pressure-bearing socket A. The drive housing is provided with a balancing chamber for receiving external mud, a delivery pipe A for conveying cables and hydraulic oil, and an isolation piston and spring sleeved on the delivery pipe A. The driving part includes a motor sequentially arranged in a driving housing, a motor transmission rod and a torque limiter sequentially connected to the motor shaft; The screw rod part includes a screw rod installed in the drive housing and connected to the torque limiter, a screw rod sleeve sleeved on the screw rod, and a push tube connected to the screw rod sleeve; The push part includes a push rod cylinder installed in the drive housing, six push rods symmetrically distributed in the push rod cylinder, and a delivery pipe B located inside the push rod cylinder and connected to the push tube; The measuring unit includes measuring arms connected to six push rods, a measuring cylinder that accommodates the measuring arms and is connected to the drive housing, and a delivery pipe C located inside the measuring cylinder and connected to the delivery pipe B. The lower joint includes a lower joint housing connected to the measuring tube and a pressure-bearing socket B installed in the lower joint housing.

2. A small-diameter six-arm caliper according to claim 1, characterized in that: The board bracket includes a mounting tube A and a mounting tube B, a frame connecting the mounting tube A and the mounting tube B, a spring installed on the outer surface of the mounting tube A, and a pressure relief washer provided at the end of the mounting tube B that contacts the pressure socket A.

3. A small-diameter six-arm caliper according to claim 2, characterized in that: An axial sliding groove A is provided on the outer surface of the multi-core plug. A pin shaft A inserted into the sliding groove A is installed on the upper connector housing; an axial sliding groove B is provided at one end of the multi-core plug for inserting the mounting cylinder A, a pin shaft B inserted into the sliding groove B is provided on the mounting cylinder A, and an axial limit key is provided on the outer circumference of the mounting cylinder B.

4. A small-diameter six-arm caliper according to claim 1, characterized in that: The screw part is installed in a screw housing, which is provided with three axial sliding grooves C. The screw sleeve is provided with three sliding blocks which are respectively inserted into the three sliding grooves C. The sliding blocks are provided with bolts which fix the screw sleeve and the push tube together.

5. The small-diameter six-arm caliper according to claim 1, characterized in that: A ranging tube is installed on the outer surface of the push tube, and a ranging groove is provided on the circumference of the outer surface of the ranging tube. A displacement sensor for measuring the moving distance of each push rod and a thrust sensor for measuring the thrust of the push tube are installed in the ranging groove. The displacement sensor and the thrust sensor are clamped and fixed in the ranging groove by multiple arc-shaped clamping rings, and a groove is provided on the inner surface of the clamping ring to fit the outer surface of the displacement sensor and the thrust sensor.

6. A small-diameter six-arm caliper according to claim 5, characterized in that: A hollow channel is provided inside the push tube, and a baffle with positioning holes is provided near one end of the push rod. The number and positions of the positioning holes on the baffle correspond to the number and positions of the push rods, and a groove for the left end of the push rod to enter is provided on the left tube body of the baffle of the push tube.

7. The small-diameter six-arm caliper according to claim 5, characterized in that: The outer surface of the measuring cylinder is provided with measuring grooves for accommodating the six measuring arms respectively. The push rod is connected to the measuring arm pin through a sealing section and two connecting rods. One end of the measuring arm is installed in the measuring groove through a pin shaft, and a protruding connecting block is provided at the connecting end. The two connecting rods are pin-connected to the connecting block, and a connecting rod groove for accommodating the two connecting rods is provided in the measuring groove.

8. The small-diameter six-arm caliper according to claim 7, characterized in that: The measuring part also includes an extension rod connected to each of the measuring arms respectively, one end of the extension rod is connected to the outer surface pin of the measuring cylinder, a connecting strip with a sliding groove D is provided on the rod body of the extension rod, the support end of the measuring arm in contact with the well wall is installed on the connecting strip through a pin inserted into the sliding groove D, and a fixed head is installed on the support end of the measuring arm, the fixed head includes a fixed head A with a pin connected to the extension rod, and a fixed head B without a pin installed when the measuring arm works independently.

9. The small-diameter six-arm caliper according to claim 8, characterized in that: An extension rod positioning sleeve is fixed on both ends of the outer surface of the measuring tube. Each extension rod positioning sleeve is provided with an opening groove corresponding to the positions of the two ends of each extension rod after being folded. The two extension rod positioning sleeves are installed with the openings of the openings facing each other.

10. The small-diameter six-arm caliper according to claim 1, characterized in that: The push rod tube and the measuring tube are plugged into each other, and a positioning key is installed at the plug-in position of the two to prevent radial rotation. One end of the delivery tube B is screwed into the measuring tube through a thread and then communicated with the delivery tube C.

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