Downhole positioning centralizer based on wedge self-locking and slice shrinkage structure

Abstract

The utility model discloses a downhole positioning centralizer based on wedge self -locking and piece shrink structure, including the centralizer body of tubular, the one end of centralizer body is fixedly connected with the sleeve, and the other end is connected with the fastening sleeve, the inner wall of fastening sleeve is connected with the one end of locking sleeve, and the outside wall of other end is the wedge inclined plane, the one end of centralizer body connection fastening sleeve inside is the wedge inclined plane with the outside wall of locking sleeve cooperation, the edge of locking sleeve both ends respectively has a plurality of long slits staggered to the inside, and long slits are evenly distributed along the circumference of locking sleeve. Through wedge self -locking, piece shrink and material optimization, ensure that the centralizer can be closely fitted on the surface of instrument, solve the problem that the existing scheme has high falling rate, short life, complicated installation etc.

Description

Technical Field

[0001] This utility model belongs to the field of downhole positioning technology of oil well logging instruments, and relates to a downhole positioning and centralizing device based on a wedge-shaped self-locking and segmented contraction structure. Background Technology

[0002] In well logging operations, due to the specific working principle requirements, some well logging instruments must be kept centered inside the wellbore to ensure measurement accuracy. The current solution is to attach a rubber centralizer or a lantern-shaped centralizer to the instrument housing, with the rubber centralizer being the most commonly used.

[0003] However, rubber stabilizers rely on hose clamps or steel wires for fixation, which are prone to detachment under frictional resistance in horizontal sections, leading to instrument misalignment or the risk of foreign object jamming in the well. Industry statistics show a detachment rate of ≥15%, and the rubber material has poor temperature resistance (≤200℃), making it prone to aging and cracking under high-temperature well conditions, failing to solve the reliability problem of the fixing structure. The invention patent "Integrated Elastic Stabilizer" with publication number CN120312126A discloses a sheet-like support structure with a thickness of ≤2mm, but according to laboratory data, the support sheet life is ≤120h, making it prone to breakage due to well wall friction. Furthermore, according to the company's operational statistics from 2019 to 2024, the probability of instrument jamming increases to over 80% after breakage, seriously affecting the safety of logging operations. Moreover, when the well inclination is >60°, it cannot adapt to changes in well diameter, leading to local overload or wear and breakage of the support sheet.

[0004] Therefore, there is an urgent need for a downhole positioning and centralizing device that can reliably prevent detachment and has better wear and impact resistance, based on existing technologies. Utility Model Content

[0005] The purpose of this invention is to provide a downhole positioning stabilizer based on a wedge-shaped self-locking and segmented contraction structure, which solves the problems of easy detachment and poor wear and impact resistance in the existing technology.

[0006] The technical solution adopted in this utility model is a downhole positioning centralizer based on a wedge-shaped self-locking and segmented contraction structure, including a cylindrical centralizer body, one end of which is threaded to a fixing sleeve, and the other end is threaded to a fastening sleeve; the inner wall of the fastening sleeve is engaged with one end of the locking sleeve, and the outer wall of the other end is a wedge-shaped inclined surface; the inner side of the end of the centralizer body connected to the fastening sleeve is a wedge-shaped inclined surface that cooperates with the outer wall of the locking sleeve; several long slits are staggered inward on both ends of the locking sleeve, and the long slits are evenly distributed along the circumference of the locking sleeve.

[0007] The features of this utility model also include: The outer side wall of the locking sleeve and the fastening sleeve has an annular groove, and the inner side wall of the fastening sleeve has an annular boss that matches the annular groove.

[0008] The annular boss and the annular groove form an interference fit with an interference amount of 0.05mm to 0.1mm.

[0009] The bevel angle of the locking sleeve is 9°~16°.

[0010] The distance between two adjacent long seams on the locking sleeve is 15mm~20mm, the seam width is 3mm~4mm, and the length of the long seam is 2 / 3~3 / 4 of the total length of the locking sleeve.

[0011] Several support arms are evenly distributed circumferentially along the middle of the outer wall of the centralizer body. The support arms are arc-shaped, and the radius of curvature of the arc is matched with that of the wellbore.

[0012] The number of support arms is 4 to 6, the arm width is 25mm to 28mm, and the gap between support arms accounts for 40% to 60%.

[0013] The body of the centralizer is made of 316L stainless steel, and the surface of the support arm is coated with a silicon carbide composite coating with a thickness of 50μm±5μm. The coating is applied using a plasma spraying process and the coefficient of friction is no greater than 0.12. The fastening sleeve is made of titanium alloy.

[0014] One end of the centralizer body is connected to the fixing sleeve and has a wrench hole for use with a dedicated torque wrench.

[0015] The end face of the fixing sleeve has a counterslip groove, which is a rectangular through hole. One set of opposite sides of the rectangular through hole is arc-shaped. The size and arc parameters of the counterslip groove are adapted to the instrument that needs to be fixed.

[0016] The beneficial effects of this utility model are: This invention, through wedge-shaped self-locking, segmented shrinkage, and material optimization, ensures that the centralizer can fit tightly against the instrument surface, solving problems such as high detachment rate, short lifespan, and complex installation of existing solutions; at the same time, it can ensure the stability of the instrument's position and attitude in the well, thereby improving the accuracy and reliability of logging data. Attached Figure Description

[0017] Figure 1 This is the front view of the downhole positioning and centralizing device based on the wedge-shaped self-locking and segmented contraction structure of this utility model; Figure 2 This is an enlarged view of the locking sleeve 4 in this utility model; Figure 3 This is a cross-sectional view of the fastening sleeve 3 in this utility model; Figure 4 This is a cross-sectional view of the fixing sleeve 2 in this utility model.

[0018] In the diagram, 1. the centralizer body, 2. the fixing sleeve, 3. the fastening sleeve, and 4. the locking sleeve. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] This utility model relates to a downhole positioning and centralizing device based on a wedge-shaped self-locking and segmented contraction structure. It is used for high-stability centralizing in logging operations of long horizontal sections and highly deviated wells, and is particularly suitable for complex conditions where well depths exceed 5000 meters and horizontal sections of the wellbore are no less than 1000 meters. Figure 1 As shown, it includes a cylindrical centralizer body 1, with a fixed sleeve 2 threaded to one end of the centralizer body 1 and a fastening sleeve 3 threaded to the other end. The inner wall of the fastening sleeve 3 is engaged with one end of the locking sleeve 4.

[0021] like Figure 2 As shown, one end of the outer wall of the locking sleeve 4 has an annular groove, and the other end has a wedge-shaped bevel with an angle of 9° to 16°. Several long slits are staggered inward along the two ends of the locking sleeve 4, and all the long slits are evenly distributed around the circumference of the locking sleeve 4. The wall thickness of the locking sleeve 4 is 3.3 to 6.2 mm, the distance between two adjacent long slits is 15 mm to 20 mm, the slit width is 3 mm to 4 mm, and the length of the long slit is 2 / 3 to 3 / 4 of the total length of the locking sleeve 4.

[0022] The inner side of one end of the centralizer body 1 connected to the fastening sleeve 3 is a wedge-shaped inclined surface that mates with the outer wall of the locking sleeve 4; several support arms are evenly distributed circumferentially in the middle of the outer wall of the centralizer body 1. The support arms are arc-shaped, and the radius of curvature of the arc is matched with that of the wellbore to provide stable support in contact with the well wall; there are 4 to 6 support arms, the arm width is 25 mm to 28 mm, and the gap between the support arms accounts for 40% to 60%, which can reduce weight and ensure efficient fluid flow.

[0023] The body of the centralizer is made of 316L stainless steel with a yield strength ≥205MPa to improve the overall durability and service life of the centralizer.

[0024] The support arm surface is coated with a silicon carbide (SiC) composite coating with a thickness of 50μm±5μm and an HV hardness of ≥1500. It is produced by plasma spraying and has a friction coefficient of ≤0.12. This coating is used to reduce resistance and friction loss with the well wall or casing wall.

[0025] The body 1 of the stabilizer is connected to the fixed sleeve 2 at one end with a wrench hole.

[0026] like Figure 3 As shown, the inner wall of the fastening sleeve 3 has an annular boss, which engages with the annular groove on the inner wall of the locking sleeve 4; the annular boss and the annular groove on the inner wall of the locking sleeve 4 form an interference fit with an interference of 0.05mm~0.1mm; the material of the fastening sleeve 3 is titanium alloy (Ti-6Al-4V) with a tensile strength ≥895MPa; the fastening sleeve 3 has a split structure and is connected by screws.

[0027] like Figure 4 As shown, the end face of the fixing sleeve 2 has a counterslip groove, which is a rectangular through hole. One set of counterslips of the rectangular through hole is arc-shaped. The size and arc parameters of the counterslip groove are adapted to the instrument that needs to be fixed. The fixing sleeve 2 is a split structure and is connected by screws.

[0028] The working principle of this downhole positioning and centralizing device based on a wedge-shaped self-locking and segmented contraction structure is as follows: The fastening sleeve 3 and the centralizer body 1 are connected by threads. By continuously tightening the fastening sleeve 3 and the centralizer body 1, the wedge-shaped inclined surface of the locking sleeve 4 contracts inside the centralizer body 1 under the pressure of the fastening sleeve 3, thereby forming a radial self-locking force ≥500N.

[0029] The installation method of this utility model's downhole positioning and centralizing device based on a wedge-shaped self-locking and segmented contraction structure is as follows: Step 1: Tighten the end of the locking sleeve 4 with the annular groove and insert it into the fastening sleeve 3 to lock it in place; Step 2: Pass the fastening sleeve 3, locking sleeve 4 and centralizer body 1 sequentially from the bottom of the No. 1 downhole instrument; Step 3: Connect the bottom of downhole instrument No. 1 to downhole instrument No. 2; Step 4: Align the opposite side slots of the fixing sleeve 2 with the flattened part of the cylindrical surface on the top of the No. 2 downhole instrument, with the threaded end of the fixing sleeve 2 facing the centralizer body 1. Use a torque wrench to assemble and tighten the two split structures of the fixing sleeve 2 with screws. Step 5: Use a special wrench to screw the body 1 of the stabilizer into the fixing sleeve 2 and tighten it; Step 6: Connect the assembled locking sleeve 4 and fastening sleeve 3 to the centralizer body 1 by thread. By continuously tightening the fastening sleeve 3, the segmented structure contracts due to the well wall pressure, triggering the wedge self-locking.

[0030] This utility model of a downhole positioning and centralizing device based on a wedge-shaped self-locking and segmented contraction structure has the following characteristics: This utility model's self-locking, anti-loosening, wear-resistant, and impact-resistant centralizer achieves zero loosening (loosening rate ≤0.5%) under downhole pressure fluctuations through a wedge-shaped self-locking and segmented shrinkage structure; the composite coating and hollow support arm design reduce the wear rate of the support structure to ≤0.1mm / thousand-hour; at the same time, it simplifies the installation process and standardizes torque wrench operation (20-80N·m).

[0031] Example 1 In this embodiment, the downhole positioning centralizer based on the wedge-shaped self-locking and segmented contraction structure includes a cylindrical centralizer body 1. One end of the centralizer body 1 is threadedly connected to a fixing sleeve 2, and the other end is threadedly connected to a fastening sleeve 3. The inner wall of the fastening sleeve 3 is engaged with one end of the locking sleeve 4, and the outer wall of the other end is a wedge-shaped inclined surface. The inner side of the end of the centralizer body 1 connected to the fastening sleeve 3 is a wedge-shaped inclined surface that cooperates with the outer wall of the locking sleeve 4. Several long slits are staggered inward at both ends of the locking sleeve 4, and the long slits are evenly distributed around the circumference of the locking sleeve 4.

[0032] Example 2 In this embodiment, the downhole positioning centralizer based on the wedge-shaped self-locking and segmented contraction structure includes a cylindrical centralizer body 1. One end of the centralizer body 1 is threadedly connected to a fixing sleeve 2, and the other end is threadedly connected to a fastening sleeve 3. The inner wall of the fastening sleeve 3 is engaged with one end of the locking sleeve 4, and the outer wall of the other end is a wedge-shaped inclined surface. The inner side of the end of the centralizer body 1 connected to the fastening sleeve 3 is a wedge-shaped inclined surface that cooperates with the outer wall of the locking sleeve 4. Several long slits are staggered inward at both ends of the locking sleeve 4, and the long slits are evenly distributed around the circumference of the locking sleeve 4.

[0033] The outer side wall of the locking sleeve 4 and the fastening sleeve 3 has an annular groove, and the inner side wall of the fastening sleeve 3 has an annular boss that matches the annular groove.

[0034] The annular boss and the annular groove form an interference fit with an interference amount of 0.05mm to 0.1mm.

[0035] The bevel angle of the locking sleeve 4 is 9°~16°.

[0036] Example 3 In this embodiment, the downhole positioning centralizer based on the wedge-shaped self-locking and segmented contraction structure includes a cylindrical centralizer body 1. One end of the centralizer body 1 is threadedly connected to a fixing sleeve 2, and the other end is threadedly connected to a fastening sleeve 3. The inner wall of the fastening sleeve 3 is engaged with one end of the locking sleeve 4, and the outer wall of the other end is a wedge-shaped inclined surface. The inner side of the end of the centralizer body 1 connected to the fastening sleeve 3 is a wedge-shaped inclined surface that cooperates with the outer wall of the locking sleeve 4. Several long slits are staggered inward at both ends of the locking sleeve 4, and the long slits are evenly distributed around the circumference of the locking sleeve 4.

[0037] The outer side wall of the locking sleeve 4 and the fastening sleeve 3 has an annular groove, and the inner side wall of the fastening sleeve 3 has an annular boss that matches the annular groove.

[0038] The annular boss and the annular groove form an interference fit with an interference amount of 0.05mm to 0.1mm.

[0039] The bevel angle of the locking sleeve 4 is 9°~16°.

[0040] The distance between two adjacent long seams on the locking sleeve 4 is 15mm~20mm, the seam width is 3mm~4mm, and the length of the long seam is 2 / 3~3 / 4 of the total length of the locking sleeve 4.

[0041] Example 4 In this embodiment, the downhole positioning centralizer based on the wedge-shaped self-locking and segmented contraction structure includes a cylindrical centralizer body 1. One end of the centralizer body 1 is threadedly connected to a fixing sleeve 2, and the other end is threadedly connected to a fastening sleeve 3. The inner wall of the fastening sleeve 3 is engaged with one end of the locking sleeve 4, and the outer wall of the other end is a wedge-shaped inclined surface. The inner side of the end of the centralizer body 1 connected to the fastening sleeve 3 is a wedge-shaped inclined surface that cooperates with the outer wall of the locking sleeve 4. Several long slits are staggered inward at both ends of the locking sleeve 4, and the long slits are evenly distributed around the circumference of the locking sleeve 4.

[0042] The outer side wall of the locking sleeve 4 and the fastening sleeve 3 has an annular groove, and the inner side wall of the fastening sleeve 3 has an annular boss that matches the annular groove.

[0043] The annular boss and the annular groove form an interference fit with an interference amount of 0.05mm to 0.1mm.

[0044] The bevel angle of the locking sleeve 4 is 9°~16°.

[0045] Several support arms are evenly distributed circumferentially in the middle of the outer wall of the centralizer body 1. The support arms are arc-shaped, and the radius of curvature of the arc is matched with that of the wellbore.

[0046] The number of support arms is 4 to 6, the arm width is 25mm to 28mm, and the gap between support arms accounts for 40% to 60%.

[0047] Example 5 In this embodiment, the downhole positioning centralizer based on the wedge-shaped self-locking and segmented contraction structure includes a cylindrical centralizer body 1. One end of the centralizer body 1 is threadedly connected to a fixing sleeve 2, and the other end is threadedly connected to a fastening sleeve 3. The inner wall of the fastening sleeve 3 is engaged with one end of the locking sleeve 4, and the outer wall of the other end is a wedge-shaped inclined surface. The inner side of the end of the centralizer body 1 connected to the fastening sleeve 3 is a wedge-shaped inclined surface that cooperates with the outer wall of the locking sleeve 4. Several long slits are staggered inward at both ends of the locking sleeve 4, and the long slits are evenly distributed around the circumference of the locking sleeve 4.

[0048] The outer side wall of the locking sleeve 4 and the fastening sleeve 3 has an annular groove, and the inner side wall of the fastening sleeve 3 has an annular boss that matches the annular groove.

[0049] The annular boss and the annular groove form an interference fit with an interference amount of 0.05mm to 0.1mm.

[0050] The bevel angle of the locking sleeve 4 is 9°~16°.

[0051] Several support arms are evenly distributed circumferentially in the middle of the outer wall of the centralizer body 1. The support arms are arc-shaped, and the radius of curvature of the arc is matched with that of the wellbore.

[0052] The body 1 of the centralizer is made of 316L stainless steel, with a composition of 16.5%~18.5% Cr, 10%~12% Ni and 2%~2.5% Mo. The surface coating of the support arm is a silicon carbide composite coating with a thickness of 50μm±5μm. It is made by plasma spraying and has a friction coefficient of no more than 0.12. The fastening sleeve 3 is made of titanium alloy.

[0053] Both the fixing sleeve 2 and the fastening sleeve 3 are split structures and are connected by screws. They can be fixed with four M6 high-strength screws (8.8 grade).

[0054] Example 6 In this embodiment, the downhole positioning centralizer based on the wedge-shaped self-locking and segmented contraction structure includes a cylindrical centralizer body 1. One end of the centralizer body 1 is threadedly connected to a fixing sleeve 2, and the other end is threadedly connected to a fastening sleeve 3. The inner wall of the fastening sleeve 3 is engaged with one end of the locking sleeve 4, and the outer wall of the other end is a wedge-shaped inclined surface. The inner side of the end of the centralizer body 1 connected to the fastening sleeve 3 is a wedge-shaped inclined surface that cooperates with the outer wall of the locking sleeve 4. Several long slits are staggered inward at both ends of the locking sleeve 4, and the long slits are evenly distributed around the circumference of the locking sleeve 4.

[0055] The outer side wall of the locking sleeve 4 and the fastening sleeve 3 has an annular groove, and the inner side wall of the fastening sleeve 3 has an annular boss that matches the annular groove.

[0056] The annular boss and the annular groove form an interference fit with an interference amount of 0.05mm to 0.1mm.

[0057] The bevel angle of the locking sleeve 4 is 9°~16°.

[0058] Several support arms are evenly distributed circumferentially in the middle of the outer wall of the centralizer body 1. The support arms are arc-shaped, and the radius of curvature of the arc is matched with that of the wellbore.

[0059] The body of the centralizer 1 is made of 316L stainless steel, and the surface of the support arm is coated with a silicon carbide composite coating with a thickness of 50μm±5μm. It adopts a plasma spraying process and has a friction coefficient of no more than 0.12. The fastening sleeve 3 is made of titanium alloy.

[0060] The centralizer body 1 is connected to the fixing sleeve 2 at one end with a wrench hole, which is compatible with a special torque wrench; the diameter of the wrench hole is 8mm, which is compatible with a special torque wrench (torque range 50N·m).

[0061] The end face of the fixing sleeve 2 has a counterslip groove. The counterslip groove is a rectangular through hole. One set of counterslips of the rectangular through hole is arc-shaped. The size and arc parameters of the counterslip groove are adapted to the instrument that needs to be fixed. The width of the counterslip groove is 90% of the outer diameter of the instrument, and it is adapted to an instrument with a diameter of φ92mm.

Claims

1. A downhole positioning centralizer based on wedge self-locking and segmented shrinkage structure, characterized in that, It includes a cylindrical stabilizer body (1), one end of the stabilizer body (1) is threaded to a fixing sleeve (2), and the other end is threaded to a fastening sleeve (3). The inner wall of the fastening sleeve (3) is engaged with one end of the locking sleeve (4), and the outer wall of the other end is a wedge-shaped slope; the inner side of the end of the stabilizer body (1) connected to the fastening sleeve (3) is a wedge-shaped slope that matches the outer wall of the locking sleeve (4); the two ends of the locking sleeve (4) have several long slits that are staggered inward, and the long slits are evenly distributed around the circumference of the locking sleeve (4).

2. The wedge-based self-locking and slice-contracting structure based downhole positioning centralizer according to claim 1, characterized in that, The outer side wall of the locking sleeve (4) and the fastening sleeve (3) is provided with an annular groove, and the inner side wall of the fastening sleeve (3) is provided with an annular boss that matches the annular groove.

3. The downhole positioning centralizer based on a wedge-shaped self-locking and segmented contraction structure according to claim 2, characterized in that, The annular boss and the annular groove form an interference fit with an interference amount of 0.05mm to 0.1mm.

4. The downhole positioning stabilizer based on a wedge-shaped self-locking and segmented contraction structure according to claim 1, characterized in that, The inclined angle of the locking sleeve (4) is 9°~16°.

5. The downhole positioning stabilizer based on a wedge-shaped self-locking and segmented contraction structure according to claim 1, characterized in that, The distance between two adjacent long seams on the locking sleeve (4) is 15mm~20mm, the seam width is 3mm~4mm, and the length of the long seam is 2 / 3~3 / 4 of the total length of the locking sleeve (4).

6. The downhole positioning stabilizer based on a wedge-shaped self-locking and segmented contraction structure according to claim 1, characterized in that, The centralizer body (1) has several support arms evenly distributed circumferentially in the middle of its outer wall. The support arms are arc-shaped, and the radius of curvature of the arc is matched with that of the wellbore.

7. The wedge self-locking and slice-contracting structure based downhole positioning centralizer according to claim 6, characterized in that, The number of support arms is 4 to 6, the arm width is 25mm to 28mm, and the gap between the support arms accounts for 40% to 60%.

8. The wedge-based self-locking and slice-contracting structure based downhole positioning centralizer according to claim 1, characterized in that, The body (1) of the centralizer is made of 316L stainless steel, and the surface of the support arm is coated with a silicon carbide composite coating with a coating thickness of 50μm±5μm. The coating is applied by plasma spraying and the friction coefficient is not greater than 0.

12. The fastening sleeve (3) is made of titanium alloy.

9. The downhole positioning stabilizer based on a wedge-shaped self-locking and segmented contraction structure according to claim 1, characterized in that, The straightener body (1) is connected to the fixing sleeve (2) at one end with a wrench hole, which is adapted to a special torque wrench.

10. The wedge self-locking and slice shrink structure based downhole positioning centralizer of claim 1, wherein, The end face of the fixing sleeve (2) has a counterslot. The counterslot is a rectangular through hole. A set of counterslots are arc-shaped. The size and arc parameters of the counterslot are adapted to the instrument that needs to be fixed.

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