Integral double-bow elastic centralizer and preparation process thereof

Abstract

The invention relates to the field of oil and gas field well drilling, and discloses an integral type double-bow elastic centralizer and a manufacturing technology thereof.The integral type double-bow elastic centralizer comprises an upper centralizing fillet and a lower centralizing fillet, one side of the upper centralizing fillet is fixedly connected with a middle hoop, one side of the middle hoop is fixedly connected to one side of the lower centralizing fillet, and the other side of the middle hoop is fixedly connected with the lower centralizing fillet; the other side of the upper centralizing fillet is fixedly connected with an end hoop, the other side of the lower centralizing fillet is fixedly connected with a tail hoop, a clamping block is arranged on one side of the end hoop, a clamping groove is formed in one side of the tail hoop, and outer wear-resistant layers are arranged on the outer sides of the upper centralizing fillet and the lower centralizing fillet. The whole pipe is subjected to laser or plasma cutting machining and formed through the heat treatment process, the structure is simple, the double-arch-shaped structure formed by the upper centralizing fillets and the lower centralizing fillets is good in elasticity centering degree, good construction conditions are provided for smooth tripping-in of a casing string, well cementation quality can be improved, and the life cycle of a shaft can be prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field drilling, in particular to an integral double-bow elastic centralizer and a preparation process thereof. Background Art

[0002] Integral elastic centralizers are made of whole materials and have a high construction safety factor. They have been widely used in the field in recent years. However, their structure is a single bow, and the effect on the centering of the casing is relatively limited. In addition, the traditional integral elastic centralizer has fewer support points on the well wall during the cementing process, which results in more friction between the pipe string and the well wall during the lowering of the pipe string. Especially in horizontal wells, because fracturing and production increase measures will be carried out in the later stage, the steel grade and wall thickness of the pipe string are higher than those of conventional pipe strings. The pipe string will be closer to the lower side of the wellbore due to gravity, and the phenomenon will be more prominent. Therefore, a centralizer with high safety, greater support and better centering is needed. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides an integral double-bow elastic stabilizer and a preparation process thereof, which solves the problem that the single-bow form has a limited effect on the centering of the casing, and the traditional integral elastic stabilizer has fewer support points on the well wall during the cementing process, which results in more friction between the pipe string and the well wall during the lowering of the pipe string.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions: an integral double-bow elastic straightener, comprising an upper straightening rib and a lower straightening rib, one side of the upper straightening rib is fixedly connected to a middle hoop, one side of the middle hoop is fixedly connected to one side of the lower straightening rib, the other side of the upper straightening rib is fixedly connected to an end hoop, and the other side of the lower straightening rib is fixedly connected to a tail hoop.

[0005] Preferably, a clamping block is provided on one side of the end hoop, and a clamping groove is provided on one side of the tail hoop.

[0006] Preferably, outer sides of the upper and lower straightening bars are provided with outer wear-resistant layers.

[0007] Preferably, five upper righting ribs and five lower righting ribs are provided, and the upper righting ribs and the lower righting ribs are distributed in an equidistant annular array with the central axis of the middle hoop as the center, and the upper righting ribs and the lower righting ribs are staggered and evenly distributed.

[0008] Preferably, the inner walls of the end hoop, the middle hoop and the tail hoop are all provided with an inner wear-resistant layer.

[0009] Preferably, the end hoop, the middle hoop and the tail hoop are all arranged on the outside of the pipe string, and the pipe string is arranged inside the wellbore.

[0010] A processing technology for an integral double-bow elastic centralizer comprises the following steps:

[0011] Step 1: Select raw materials and process them: Cut the whole tube by laser or plasma cutting;

[0012] Step 2: Process the end and tail;

[0013] Step 3: After the above is completed, deburr it;

[0014] Step 4: After the above is completed, heat treatment is performed on the centralizer;

[0015] Step 5: After the above is completed, the inner and outer walls of the centralizer are coated with a wear-resistant layer.

[0016] Preferably, in step one, the whole tube is cut by laser or plasma cutting to achieve one-time forming. When the tube is cut by laser, the power is set to 80kw and the feed speed is set to 0.5mm / s. When the tube is cut by plasma, the power is set to 100kw and the feed speed is set to 0.4mm / s.

[0017] Preferably, in step 4, heat treatment is performed to eliminate internal stress. During the heat treatment, the pipe is first heated to 800°C to 950°C, then the heated pipe is kept at this temperature for 3 to 3.5 hours, and finally transferred to room temperature and cooled at room temperature.

[0018] Preferably, in step five, the method for applying the wear-resistant coating adopts high-temperature sintering technology, the sintering temperature is 650° C. to 700° C., and the sintering time is 2 hours.

[0019] The present invention provides an integral double-bow elastic centralizer and a preparation process thereof. It has the following beneficial effects:

[0020] 1. The present invention forms the whole pipe by laser or plasma cutting and heat treatment process, and has a simple structure. The double-bow structure formed by the upper and lower straightening ribs has good elastic centering, which provides good construction conditions for the smooth lowering of the casing string, improves the cementing quality, and prolongs the life cycle of the wellbore.

[0021] 2. The present invention utilizes a double-bow mode formed by upper and lower righting bars, and the upper and lower arch righting bars are staggered and evenly distributed, which has better centering support force than the single-bow mode. At the same time, there is a hollow structure between two adjacent righting bars, which is beneficial to the later circulation of cleaning the sand and rock debris at the bottom of the well. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0023] Figure 2 It is a front cross-sectional view of the end hoop of the present invention;

[0024] Figure 3 It is a front cross-sectional view of the upper straightening rib of the present invention;

[0025] Figure 4 It is a front cross-sectional view of the middle hoop of the present invention;

[0026] Figure 5 It is a front cross-sectional view of the lower straightening rib of the present invention;

[0027] Figure 6 It is a front cross-sectional view of the tail hoop of the present invention;

[0028] Figure 7 It is a schematic diagram of an embodiment of the present invention.

[0029] Among them, 1. upper straightening rib; 2. lower straightening rib; 3. middle hoop; 4. end hoop; 5. tail hoop; 6. slot; 7. block; 8. outer wear-resistant layer; 9. inner wear-resistant layer; 10. wellbore; 11. pipe string. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example:

[0032] Please see attached Figure 1 , Figure 2 , Figure 6 and Figure 7 An embodiment of the present invention provides an integral double-bow elastic straightener, comprising an upper straightening bar 1 and a lower straightening bar 2, one side of the upper straightening bar 1 is fixedly connected to a middle hoop 3, one side of the middle hoop 3 is fixedly connected to one side of the lower straightening bar 2, the other side of the upper straightening bar 1 is fixedly connected to an end hoop 4, and the other side of the lower straightening bar 2 is fixedly connected to a tail hoop 5.

[0033] During use, the centralizer is sleeved on the outside of the pipe, and the centralizer pipe is placed at the bottom of the lowest pipe string by using a connecting assembly. By continuously conveying the pipe into the wellbore 10, the upper and lower centralizing bars 1 and 2 are used to avoid collision between the pipe and the side wall of the wellbore 10, thereby keeping the pipe centered inside the wellbore 10. In addition, during the cementing process, the elastic double-bow shape formed by the upper and lower centralizing bars 1 and 2 can increase the support force on the well wall of the centralizer, provide greater support force on the casing, reduce friction during the lowering of the pipe string, provide good construction conditions for the smooth lowering of the casing string 11, and improve the cementing quality, thereby extending the life cycle of the wellbore.

[0034] refer to Figure 2 and Figure 6 A clamping block 7 is provided on one side of the end hoop 4 , and a clamping groove 6 is provided on one side of the tail hoop 5 .

[0035] By providing a clamping block 7 on one side of the end hoop 4 and a clamping groove 6 on one side of the tail hoop 5, when the centralizer is installed at the bottom of the pipe string, the centralizer can be clamped at the bottom of the pipe string using a connecting assembly, thereby preventing the centralizer from rotating when it is lowered into the wellbore 10.

[0036] refer to Figure 3 and Figure 5 The outer sides of the upper straightening strips 1 and the lower straightening strips 2 are both provided with outer wear-resistant layers 8.

[0037] By providing an outer wear-resistant layer 8 on the outer side of the upper righting bar 1 and the lower righting bar 2, the durability and permanence of the upper righting bar 1 and the lower righting bar 2 can be improved, and the outer wear-resistant layer 8 can be used to avoid excessive friction between the upper righting bar 1 and the lower righting bar 2 and the side wall of the wellbore 10 during the process of lowering into the wellbore 10, thereby preventing the upper righting bar 1 and the lower righting bar 2 from losing their protective effect. Therefore, by providing the outer wear-resistant layer 8, the upper righting bar 1 and the lower righting bar 2 can be better protected, and since the wear is reduced, the service life of the upper righting bar 1 and the lower righting bar 2 will be extended accordingly, reducing the frequency of replacement or maintenance. At the same time, the outer wear-resistant layer 8 can reduce the risk of component failure due to wear, thereby improving the overall safety of the system.

[0038] refer to Figure 1 There are five upper straightening bars 1 and five lower straightening bars 2, and the upper straightening bars 1 and the lower straightening bars 2 are distributed in an equidistant circular array with the central axis of the middle hoop 3 as the center, and the upper straightening bars 1 and the lower straightening bars 2 are staggered and evenly distributed.

[0039] By setting the upper righting ribs 1 and the lower righting ribs 2 to be staggered and evenly distributed, the stability of the structure can be increased, the load can be evenly distributed, and local stress concentration can be reduced. The five upper righting ribs 1 and the five lower righting ribs are distributed in the upper and lower layers and are staggered and evenly distributed, which helps to provide multi-directional support, thereby improving the overall stability of the structure. The setting of multiple righting ribs can not only provide support in the vertical direction, but also provide additional strength and rigidity in the horizontal direction, and also help to disperse the force generated by external impact or vibration, thereby improving the impact and vibration resistance of the system. There is a hollow structure between two adjacent righting ribs, which is conducive to the cleaning of sand and rock debris at the bottom of the well in the later cycle.

[0040] refer to Figure 2 , Figure 4 and Figure 6 The inner walls of the end hoop 4 , the middle hoop 3 and the tail hoop 5 are all provided with an inner wear-resistant layer 9 .

[0041] By providing an inner wear-resistant layer 9 on the inner walls of the end hoop 4, the middle hoop 3 and the tail hoop 5, the inner wear-resistant layer 9 can be used to protect the contact surfaces between the end hoop 4, the middle hoop 3 and the tail hoop 5 and the pipe string 11, so as to avoid large wear between the contact surfaces between the end hoop 4, the middle hoop 3 and the tail hoop 5 and the pipe string 11 during the lowering process, resulting in large gaps between the contact surfaces between the end hoop 4, the middle hoop 3 and the tail hoop 5 and the pipe string 11, thereby reducing the wear on the inner walls of each hoop, significantly extending its service life, thereby reducing the need for maintenance and replacement, reducing the overall operating cost, and ensuring that each hoop can maintain good performance throughout its service life, thereby reducing risks.

[0042] The end hoop 4 , the middle hoop 3 and the tail hoop 5 are all arranged outside the pipe string 11 , and the pipe string 11 is arranged inside the wellbore 10 .

[0043] A preparation process of an integral double-bow elastic centralizer comprises the following steps:

[0044] Step 1: Select raw materials and process them: Cut the whole tube by laser or plasma cutting;

[0045] In step 1, the whole pipe is cut by laser or plasma cutting to achieve one-time forming. When the pipe is cut by laser, the power is set to 80kw and the feed speed is set to 0.5mm / s. When the pipe is cut by plasma, the power is set to 100kw and the feed speed is set to 0.4mm / s. The raw material is spring steel material, and the composition of the spring steel material is carbon (C): 0.4%~0.8%, silicon (Si) 0.1%~0.28%, manganese (Mn) 0.7% to 0.88%, chromium (Cr) 0.5% to 2.2%, molybdenum (Mo) 0.2% to 0.8%, nickel (Ni) 0.8% to 1.2%, titanium (Ti) 0.2% to 0.4%, tubular spring steel is selected as the raw material, and the specific design parameters of the centralizer are determined through design and planning. Then, the tubular raw material is stamped into a shape that meets the shape of the centralizer by stamping, and then the stamped pipe is cut by laser or plasma cutting to cut out the hollow part between the upper centralizing rib 1 and the lower centralizing rib 2.

[0046] Step 2: Process the end and tail;

[0047] Then, the pipe after cutting is moved to a milling machine, and the end hoop 4 is processed by the milling machine to mill out the clamping block 7 on the end hoop 4, and then the tail hoop 5 is processed to mill out the clamping groove 6 on the tail hoop 5.

[0048] Step 3: After the above is completed, deburr it;

[0049] When the pipe processing is completed, the shape of the pipe is basically determined. Then, the angle grinder is used to deburr the pipe after the shape processing. By removing the burrs, sharp edges and rough surfaces caused by the presence of burrs can be avoided. Therefore, when the pipe is moved, the risk of injury is reduced. By removing the burrs, sharp edges can be eliminated to improve product safety. At the same time, the surface of the pipe is also made smooth, so that the coating can be better adhered to the surface when the paint is applied later, thereby improving the adhesion and durability of the coating. In addition, during the assembly process, removing burrs can reduce friction and jamming, and improve assembly efficiency and quality.

[0050] Step 4: After the above is completed, heat treatment is performed on the centralizer;

[0051] In step 4, heat treatment is performed to eliminate internal stress. After the pipe is deburred, the pipe is annealed. The stress generated during the processing of the pipe can be eliminated by annealing. The annealing process can release and reduce the stress inside the material through heating and slow cooling, thereby reducing deformation, cracking and distortion caused by stress. During the annealing process, the pipe is first heated to 800°C to 950°C, and then the heated pipe is kept at this temperature for 3 to 3.5 hours, and finally it is transferred to room temperature and cooled at room temperature.

[0052] Step 5: After the above is completed, the inner and outer walls of the centralizer are coated with a wear-resistant layer.

[0053] In step 5, the method for coating the anti-friction coating adopts high-temperature sintering technology, the sintering temperature is 650°C to 700°C, the sintering time is 2h, and after the cooling of the pipe is completed, the inner and outer walls of the pipe are coated with an inner wear-resistant layer 9 and an outer wear-resistant layer 8 by a spray gun, and the inner and outer wear-resistant layers 9 and 8 have the same composition, both of which are zirconium oxide coatings. The wear resistance and corrosion resistance of the zirconium oxide coating are used to protect the pipe, and the composition is zirconium oxide (ZrO2) 92.5% to 95.5%, stabilizer 1.5% to 2.2%, and other additives 0.7% to 2%.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An integral double-bow elastic centralizer, comprising an upper centralizing strip (1) and a lower centralizing strip (2), characterized in that: One side of the upper straightening bar (1) is fixedly connected to a middle hoop (3), one side of the middle hoop (3) is fixedly connected to one side of the lower straightening bar (2), the other side of the upper straightening bar (1) is fixedly connected to an end hoop (4), and the other side of the lower straightening bar (2) is fixedly connected to a tail hoop (5).

2. The integrated double-bow elastic centralizer according to claim 1, characterized in that: A clamping block (7) is provided on one side of the end ring hoop (4), and a clamping groove (6) is provided on one side of the tail ring hoop (5).

3. The integrated double-bow elastic centralizer according to claim 1, characterized in that: The outer sides of the upper straightening strips (1) and the lower straightening strips (2) are both provided with outer wear-resistant layers (8).

4. The integrated double-bow elastic centralizer according to claim 1, characterized in that: The upper straightening bars (1) and the lower straightening bars (2) are each provided with five, and the upper straightening bars (1) and the lower straightening bars (2) are distributed in an equidistant annular array with the central axis of the middle hoop (3) as the center, and the upper straightening bars (1) and the lower straightening bars (2) are staggered and evenly distributed.

5. The integrated double-bow elastic centralizer according to claim 1, characterized in that: The inner walls of the end hoop (4), the middle hoop (3) and the tail hoop (5) are all provided with an inner wear-resistant layer (9).

6. The integrated double-bow elastic centralizer according to claim 1, characterized in that: The end hoop (4), the middle hoop (3) and the tail hoop (5) are all arranged outside the pipe string (11), and the pipe string (11) is arranged inside the wellbore (10).

7. A processing technology for an integral double-bow elastic centralizer, characterized in that: The method for manufacturing an integral double-bow elastic centralizer as claimed in any one of claims 1 to 6 comprises the following steps: Step 1: Select raw materials and process them: Cut the whole tube by laser or plasma cutting; Step 2: Process the end and tail; Step 3: After the above is completed, deburr it; Step 4: After the above is completed, heat treatment is performed on the centralizer; Step 5: After the above is completed, the inner and outer walls of the centralizer are coated with a wear-resistant layer.

8. The preparation process of the integrated double-bow elastic centralizer according to claim 7, characterized in that: In the step 1, the whole tube is cut by laser or plasma cutting to achieve one-time forming. When the tube is cut by laser, the power is set to 80kw and the feed speed is set to 0.5mm / s. When the tube is cut by plasma, the power is set to 100kw and the feed speed is set to 0.4mm / s.

9. The preparation process of an integral double-bow elastic centralizer according to claim 7, characterized in that: In step 4, heat treatment is performed to eliminate internal stress. During the heat treatment, the pipe is first heated to 800°C to 950°C, then the heated pipe is kept at this temperature for 3 to 3.5 hours, and finally transferred to room temperature and then cooled at room temperature.

10. The preparation process of an integral double-bow elastic centralizer according to claim 7, characterized in that: In the step 5, the method for applying the wear-resistant coating adopts high-temperature sintering technology, the sintering temperature is 650° C. to 700° C., and the sintering time is 2 hours.

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