Flexible logging instrument and manufacturing method of flexible pipe of flexible logging instrument

Abstract

The invention relates to a flexible logging instrument and a manufacturing method of a flexible pipe of the flexible logging instrument, and relates to the technical field of oil exploration. The flexible logging instrument comprises a flexible pipe, the flexible pipe is made of metal, the flexible pipe comprises an inner pipe and an outer pipe arranged outside the inner pipe in a sleeving mode, the inner pipe comprises straight pipe sections and corrugated pipe sections, the straight pipe sections and the corrugated pipe sections are alternately arranged, a plurality of kerfs are formed in the outer pipe, and the outer pipe is divided into a plurality of independent pipe joints through the kerfs. The inner pipe in the flexible pipe comprises the corrugated pipe section, so that the inner pipe has certain telescopic capacity and bending capacity, and the straight pipe section in the inner pipe ensures certain structural strength while having the telescopic capacity and the bending capacity. The outer pipe arranged outside the inner pipe in a sleeving mode forms a plurality of independent pipe joints through a plurality of formed kerfs, the kerfs enable the pipe joints to move relative to one another, the outer pipe also has certain telescopic capacity and bending capacity, and the logging instrument can be bent, stretched and retracted to a certain degree in the underground logging process.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration technology, and in particular to a flexible logging tool and a method for manufacturing its flexible tube. Background Technology

[0002] Direct-push logging systems, a popular construction technique, involve attaching logging instruments to the front of the drill string and pushing them forward for logging. Due to the long instrument string, flexible logging tools are needed in highly deviated and horizontal well sections to ensure safe and reliable passage. Traditionally, flexible logging tools have employed internal oil injection into rubber tubing to achieve pressure balance and protect the core wire.

[0003] With the increasing number of deep and ultra-deep wells, the corrosive effect of hydrogen sulfide gas inside the well on rubber is severe. Hydrogen sulfide gas enters the rubber tube through the structure between rubber molecules. When there is too much gas, it can easily cause the rubber tube to burst and be damaged, thereby disrupting the pressure balance of the entire instrument, causing instrument damage, and affecting logging operations. At the same time, the long-term high temperature environment can also easily cause the rubber to harden and lose its elasticity. Summary of the Invention

[0004] This invention provides a flexible logging tool and a method for manufacturing the flexible tube thereof. The flexible logging tool includes a flexible tube made of metal, which gives the flexible logging tool the characteristics of strong corrosion resistance and high temperature resistance.

[0005] On one hand, the present invention provides a flexible logging tool, including a flexible tube made of metal. The flexible tube includes an inner tube and an outer tube sleeved outside the inner tube. The inner tube includes straight pipe sections and corrugated pipe sections, which are alternately arranged. The outer tube has multiple slits that divide the outer tube into multiple independent pipe sections.

[0006] In one embodiment, the two ends of the outer tube are respectively connected to a compensation tube and a lower connecting tube, and the two ends of the inner tube are respectively provided with a first connector and a second connector. The first connector is inserted into the interior of the compensation tube, and a first sealing ring is provided between the outer wall of the first connector and the inner wall of the compensation tube. The second connector is inserted into the interior of the lower connecting tube, and a second sealing ring is provided between the outer wall of the second connector and the inner wall of the lower connecting tube.

[0007] In one embodiment, the surface of the first connector is provided with an annular groove, and one end of the outer tube is provided with a limiting member, which is inserted into the annular groove.

[0008] In one embodiment, the limiting member is a bolt, and at least three limiting members are provided and are equally spaced along the circumference of the outer tube, with the ends of the limiting members spaced apart from the bottom of the annular groove.

[0009] In one embodiment, the end of the compensation pipe away from the flexible pipe is connected to the upper connecting pipe. The compensation pipe is provided with a one-way valve and an overflow valve, and oil is injected into the compensation pipe and the inner pipe through the one-way valve.

[0010] In one embodiment, the compensation tube has multiple through holes, each through hole being a stepped hole. A plunger is provided inside each through hole, and the plunger can reciprocate along the radial direction of the compensation tube. A third sealing ring is provided between the plunger and the wall of the through hole.

[0011] In one embodiment, the wall of the through hole is further provided with a mounting groove, and a retaining spring is provided in the mounting groove to limit the plunger.

[0012] In one embodiment, a protective spring is wound around the outer wall of the inner tube, and the protective spring covers all the bellows sections.

[0013] On the other hand, a method for manufacturing the flexible tube of a flexible logging tool is provided, comprising the following steps:

[0014] S1. The annular metal disc is bent to form a stepped structure, so that the inner ring side of the annular metal disc forms a first connecting part and the outer ring side of the annular metal disc forms a second connecting part, and the metal tube is cut into at least two straight tube segments.

[0015] S2. Weld multiple annular metal discs to connect the first connecting parts of adjacent annular metal discs to each other, and connect the second connecting parts of adjacent annular metal discs to each other, to obtain a corrugated pipe section.

[0016] S3. Weld the ends of the corrugated pipe sections to the ends of the straight pipe sections, and alternate between the corrugated pipe sections and the straight pipe sections to obtain a flexible pipe.

[0017] In one embodiment, in step S1, the annular metal disc after bending further includes a first bending portion, a second bending portion, and a third connecting portion disposed between the first connecting portion and the second connecting portion. The two sides of the first bending portion are respectively connected to one side of the first connecting portion and one side of the third connecting portion, and the two sides of the second bending portion are respectively connected to one side of the second connecting portion and the other side of the third connecting portion.

[0018] Compared with existing technologies, the advantages of this invention are as follows: the inner tube of the flexible tube, due to its corrugated sections, possesses a certain degree of expansion and contraction capability, while the straight sections within the inner tube ensure structural strength while maintaining this capability. The outer tube, fitted over the inner tube, is formed into multiple independent sections through various slits. These slits allow relative movement between the sections, giving the outer tube a degree of expansion and contraction capability as well, while also providing some protection for the inner tube. Because the flexible tube as a whole possesses a certain degree of expansion and contraction capability, and is made of metal rather than rubber, the logging tool can achieve a certain degree of bending and expansion during downhole logging, ensuring the tool can pass through highly deviated wells while maintaining corrosion resistance and high-temperature resistance. Attached Figure Description

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

[0020] Figure 1 This is a side view of the flexible logging tool in an embodiment of the present invention;

[0021] Figure 2 This is a cross-sectional view of the flexible logging tool in an embodiment of the present invention;

[0022] Figure 3 This is a structural diagram of the inner tube in an embodiment of the present invention;

[0023] Figure 4 This is a half-sectional view of the outer tube in an embodiment of the present invention;

[0024] Figure 5 yes Figure 2 Enlarged view of point A in the middle;

[0025] Figure 6 yes Figure 2 Enlarged view of point B in the middle;

[0026] Figure 7 yes Figure 2 Enlarged view of point C in the middle;

[0027] Figure 8 This is a cross-sectional view of the connection between the flexible tube and the compensation tube in an embodiment of the present invention;

[0028] Figure 9 yes Figure 3 Enlarged view at point D;

[0029] Figure 10 This is a flowchart illustrating the manufacturing method of the flexible logging tool in an embodiment of the present invention.

[0030] Figure label:

[0031] 1. Flexible pipe; 11. Inner pipe; 111. Straight pipe section; 112. Corrugated pipe section; 1121. Annular metal disc; 11211. First connecting part; 11212. Second connecting part; 11213. First bending part; 11214. Second bending part; 11215. Third connecting part; 113. First joint; 114. Second joint; 115. First sealing ring; 116. Second sealing ring ; 12. Outer pipe; 121. Pipe section; 122. Limiting element; 13. Protective spring; 2. Compensating pipe; 21. One-way valve; 22. Overflow valve; 23. Vent screw; 24. Plunger; 25. Snap ring; 26. Third sealing ring; 3. Lower connecting pipe; 31. Pressure plate; 4. Upper connecting pipe; 41. Sealing plug; 5. Protective cap; 6. Plug; 100. Cut; 200. Annular groove; 300. Through hole. Detailed Implementation

[0032] The invention will now be further described with reference to the accompanying drawings.

[0033] Example 1

[0034] like Figures 1 to 4 As shown, a flexible logging tool according to an embodiment of the present invention includes a flexible tube 1, which is made of metal. The flexible tube 1 includes an inner tube 11 and an outer tube 12 sleeved outside the inner tube 11. The inner tube 11 includes a straight pipe section 111 and a corrugated pipe section 112, which are alternately arranged. The outer tube 12 has multiple slits 100, which divide the outer tube 12 into multiple independent pipe sections 121.

[0035] The inner tube 11 of the flexible tube 1, comprising multiple corrugated sections 112, possesses a certain degree of expansion and contraction capability and bending capacity. The straight sections 111 within the inner tube 11 ensure structural strength while maintaining this expansion and contraction capability. The outer tube 12, fitted over the inner tube 11, forms multiple independent tube sections 121 through multiple slits 100. These slits allow relative movement between the tube sections 121, giving the outer tube 12 a certain degree of expansion and contraction capability and also providing some protection to the inner tube 11. Because the flexible tube 1 as a whole possesses a certain degree of expansion and contraction capability and is made of metal rather than rubber, the logging tool can achieve a certain degree of bending and expansion during downhole logging, ensuring the tool can pass through highly deviated wells while maintaining corrosion resistance and high-temperature resistance.

[0036] like Figure 2 and Figure 3 As shown, the two ends of the outer tube 12 are connected to the compensation tube 2 and the lower connecting tube 3, respectively, and the two ends of the inner tube 11 are respectively provided with a first connector 113 and a second connector 114. Figures 5 to 7As shown, the first connector 113 is inserted into the interior of the compensating pipe 2, and a first sealing ring 115 is provided between the outer wall of the first connector 113 and the inner wall of the compensating pipe 2. The second connector 114 is inserted into the interior of the lower connecting pipe 3, and a second sealing ring 116 is provided between the outer wall of the second connector 114 and the inner wall of the lower connecting pipe 3. The outer pipe 12 has a thicker wall and higher structural strength, so both the compensating pipe 2 and the lower connecting pipe 3 are connected to the outer pipe 12 to ensure high connection strength and prevent excessive stress on the inner pipe 11, which could cause structural damage. By setting the first sealing ring 115 and the second sealing ring 116, a sealing function is achieved, and the two ends of the inner pipe 11 are also radially limited, thereby improving the stability of the inner pipe 11.

[0037] like Figure 5 and Figure 8 As shown, the surface of the first connector 113 is provided with an annular groove 200, and one end of the outer tube 12 is provided with a limiting member 122, which is inserted into the annular groove 200. The length of the flexible logging tool is different under tension and compression. When the length of the flexible logging tool changes, the inner tube 11 will expand and contract. The limiting member 122 and the annular groove 200 ensure that the first connector 113 can only move within a certain length range, thereby limiting the length change of the inner tube 11 and preventing the inner tube 11 from being too long or too short, thus protecting the inner tube 11.

[0038] Furthermore, in this embodiment, the limiting member 122 is a bolt. At least three limiting members 122 are provided and are evenly spaced along the circumference of the outer tube 12. The ends of the limiting members 122 are spaced apart from the bottom of the annular groove 200. By opening corresponding threaded holes on the outer tube 12, the limiting members 122 can be easily fixed to the outer tube 12. Providing a larger number of limiting members 122 reduces the force on each individual limiting member 122 and disperses the force points on the first joint 113, resulting in higher structural reliability and better limiting effect. Because the ends of the limiting members 122 are spaced apart from the bottom of the annular groove 200, the ends of the limiting members 122 do not rub against the surface of the first joint 113, thus not hindering the movement of the first joint 113.

[0039] like Figure 5As shown, the end of the compensation pipe 2 furthest from the flexible pipe 1 is connected to the upper connecting pipe 4. The compensation pipe 2 is equipped with a one-way valve 21 and an overflow valve 22. Oil is injected into the compensation pipe 2 and the inner pipe 11 through the one-way valve 21. The one-way valve 21 prevents backflow during oil injection and automatically closes after injection to prevent oil overflow. After oil is injected into the compensation pipe 2, the oil fills the interior of the inner pipe 11 and the interior of the compensation pipe 2. After being lowered into the well, the pressure increases and the oil expands. At this time, the overflow valve 22 releases pressure, allowing a small amount of oil to overflow, thereby achieving internal and external pressure balance to protect the instrument. The compensation pipe 2 is also equipped with a vent screw 23. During oil injection, the vent screw 23 is unscrewed to release air from inside the flexible logging tool. After oil injection, the vent screw 23 is tightened to prevent air from being trapped inside.

[0040] like Figure 6 As shown, the compensation pipe 2 has multiple through holes 300, which are stepped holes. A plunger 24 is installed inside each through hole 300, and the plunger 24 can reciprocate along the radial direction of the compensation pipe 2. A third sealing ring 26 is provided between the plunger 24 and the wall of the through hole 300. The stepped design of the through hole 300 limits the lower stop point of the plunger 24 while allowing it to move. During initial oil injection, the plunger 24 is pushed up by the oil pressure. After being lowered into the well, the plunger 24 cannot continue to move upwards when the oil expands. At this time, the overflow valve 22 releases pressure, overflowing a small amount of oil, thus achieving internal and external pressure balance. Later, when the pressure decreases, the internal oil expansion pressure is insufficient, and the plunger 24 moves downwards to compensate. Thus, the up-and-down movement of the plunger 24 achieves automatic pressure regulation within a certain range, better protecting the instrument.

[0041] Furthermore, the through-hole 300 is provided with a mounting groove (not shown in the figure) on its wall, and a retaining spring 25 is provided in the mounting groove to limit the plunger 24. Since the through-hole 300 is a stepped hole, the plunger 24 can only be inserted into the through-hole 300 from the outside of the compensating tube 2. However, in order to prevent the plunger 24 from falling out of the through-hole 300, a corresponding limiting structure must be provided. Therefore, a removable retaining spring 25 is used to limit the upper stop point of the plunger 24. After the plunger 24 is inserted into the through-hole 300, the retaining spring 25 is placed into the mounting groove in the through-hole 300 so that the retaining spring 25 can block the plunger 24. When it is necessary to remove the plunger 24, only the retaining spring 25 needs to be removed, which is very convenient.

[0042] like Figure 5 As shown, a protective spring 13 is wound around the outer wall of the inner tube 11, and the protective spring 13 covers all the bellows sections 112. The protective spring 13 is made of tightly wound stainless steel alloy wire. Since the protective spring 13 covers the surface of the bellows section 112, it can prevent gravel and other debris from entering from the cut 100 of the outer tube 12 from damaging the bellows section 112.

[0043] like Figure 1 and Figure 2 As shown, the flexible logging tool in this embodiment also includes an upper connecting pipe 4, a protective cap 5, and a plug 6. The upper connecting pipe 4 is connected to the end of the compensation pipe 2 away from the flexible pipe 1. The protective cap 5 is connected to the upper connecting pipe 4, and the plug 6 is connected to the lower connecting pipe 3. The protective cap 5 and the plug 6 are used to protect both ends of the flexible logging tool and prevent external impurities from entering the instrument and damaging it.

[0044] like Figure 6 and Figure 7 As shown, the upper connecting pipe 4 is equipped with a sealing plug 41, and the lower connecting pipe 3 is equipped with a pressure plate 31. The sealing plug 31 and the pressure plate 41 can seal the oil inside the flexible logging tool to prevent the oil from overflowing.

[0045] Example 2

[0046] like Figure 9 and Figure 10 As shown, embodiments of the present invention also provide a method for manufacturing a flexible tube for a flexible logging tool, comprising the following steps:

[0047] S1. The annular metal disc 1121 is bent to form a stepped structure, so that the inner ring side of the annular metal disc 1121 forms a first connecting part 11211 and the outer ring side of the annular metal disc 1121 forms a second connecting part 11212, and the metal tube is cut into at least two straight pipe sections 111.

[0048] S2. Welding is performed on multiple annular metal discs 1121 so that the first connecting parts 11211 of adjacent annular metal discs 1121 are connected to each other and the second connecting parts 11212 of adjacent annular metal discs 1121 are connected to each other to obtain a corrugated pipe section 112.

[0049] S3. Weld the end of the corrugated pipe section 112 to the end of the straight pipe section 111, and alternately set the corrugated pipe section 112 and the straight pipe section 111 to obtain the flexible pipe 1.

[0050] The annular metal disc 1121, after being bent into a stepped structure, possesses a certain degree of deformation capability, giving the corrugated pipe section 112 good expansion and contraction performance. In this embodiment, the annular metal disc 1121 is made of a nickel-based high-temperature alloy, while the straight pipe section 111 is made of stainless steel, giving the resulting flexible pipe 1 the advantages of high temperature resistance and corrosion resistance. The annular metal disc 1121 is welded using a fully automatic laser welding machine, and the corrugated pipe section 112 is tested using an airtightness testing device after processing to ensure welding reliability.

[0051] Furthermore, in step S1, the annular metal disc 1121 after bending further includes a first bending portion 11213, a second bending portion 11214, and a third connecting portion 11215 disposed between the first connecting portion 11211 and the second connecting portion 11212. The two sides of the first bending portion 11213 are respectively connected to one side of the first connecting portion 11211 and one side of the third connecting portion 11215. The two sides of the second bending portion 11214 are respectively connected to one side of the second connecting portion 11212 and the other side of the third connecting portion 11215, so that there are four bends on a single annular metal disc 1121, which greatly improves the deformation capability of the annular metal disc 1121.

[0052] In this embodiment, when no force is applied, the first connecting portion 11211, the second connecting portion 11212, and the third connecting portion 11215 are parallel to each other, and the first bending portion 11213 and the second bending portion 11214 are parallel to each other. When the bellows section 112 is subjected to tension or compression, the shape of the annular metal discs 1121 and the spacing between them change. By welding a sufficient number of annular metal discs 1121, the bellows section 112 can always undergo elastic deformation and quickly return to its original shape after no force is applied.

[0053] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A flexible logging tool, characterized in that, The system includes a flexible tube made of metal, comprising an inner tube and an outer tube fitted over the inner tube. The inner tube includes straight sections and corrugated sections, which are alternately arranged. The outer tube has multiple slits that divide it into multiple independent sections.

2. The flexible logging tool according to claim 1, characterized in that, The outer tube is connected to a compensation tube and a lower connecting tube at both ends, and the inner tube is provided with a first connector and a second connector at both ends. The first connector is inserted into the interior of the compensation tube, and a first sealing ring is provided between the outer wall of the first connector and the inner wall of the compensation tube. The second connector is inserted into the interior of the lower connecting tube, and a second sealing ring is provided between the outer wall of the second connector and the inner wall of the lower connecting tube.

3. The flexible logging tool according to claim 2, characterized in that, The surface of the first connector is provided with an annular groove, and one end of the outer tube is provided with a limiting member, which is inserted into the annular groove.

4. The flexible logging tool according to claim 3, characterized in that, The limiting member is a bolt, and at least three limiting members are provided and are equally spaced along the circumference of the outer tube. The end of the limiting member is spaced apart from the bottom of the annular groove.

5. The flexible logging tool according to claim 2, characterized in that, The end of the compensation pipe away from the flexible pipe is connected to the upper connecting pipe. The compensation pipe is equipped with a one-way valve and an overflow valve. Oil is injected into the compensation pipe and the inner pipe through the one-way valve.

6. The flexible logging tool according to claim 5, characterized in that, The compensation tube has multiple through holes, which are stepped holes. A plunger is provided inside the through hole. The plunger can reciprocate along the radial direction of the compensation tube. A third sealing ring is provided between the plunger and the hole wall of the through hole.

7. The flexible logging tool according to claim 6, characterized in that, The through hole is also provided with a mounting groove, and a retaining spring is provided in the mounting groove to limit the plunger.

8. The flexible logging tool according to claim 1, characterized in that, The outer wall of the inner tube is wound with a protective spring, which covers all the corrugated tube sections.

9. A method for manufacturing the flexible tube of a flexible logging tool, characterized in that, Includes the following steps: S1. The annular metal disc is bent to form a stepped structure, so that the inner ring side of the annular metal disc forms a first connecting part and the outer ring side of the annular metal disc forms a second connecting part, and the metal tube is cut into at least two straight tube segments. S2. Weld multiple annular metal discs to connect the first connecting parts of adjacent annular metal discs to each other, and connect the second connecting parts of adjacent annular metal discs to each other, to obtain a corrugated pipe section. S3. Weld the ends of the corrugated pipe sections to the ends of the straight pipe sections, and alternate between the corrugated pipe sections and the straight pipe sections to obtain a flexible pipe.

10. The method for manufacturing the flexible tube of the flexible logging tool according to claim 9, characterized in that, In step S1, the annular metal disc after bending further includes a first bending portion, a second bending portion, and a third connecting portion disposed between the first connecting portion and the second connecting portion. The two sides of the first bending portion are respectively connected to one side of the first connecting portion and one side of the third connecting portion, and the two sides of the second bending portion are respectively connected to one side of the second connecting portion and the other side of the third connecting portion.

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