A small casing gravel pack sand control tool and method of use

Abstract

The present application relates to the technical field of oil exploitation, and particularly relates to a small casing gravel packing sand prevention tool and a use method. The technical scheme is as follows: liquid holes are distributed on the outer wall of an outer pipe, a wire is wound on the outer wall, one or more than one supporting rib is arranged between the wire and the outer wall of the outer pipe, and the lower end of the outer pipe is connected with a screen pipe through a lower joint; the upper end of an inner pipe is installed with a cylinder sleeve, the upper end of the cylinder sleeve is connected with an upper joint, the lower end of the inner pipe is connected with a jet pipe through an inner lower joint; a plurality of well washing holes are arranged on the upper part of the inner pipe, a piston and a spring are arranged between the cylinder sleeve and the outer part of the well washing hole of the inner pipe, and a plurality of circulating well washing holes are arranged on the cylinder sleeve; the outer wall of the upper joint is connected with the inner wall of the upper part of the outer pipe through a lock block and a shear pin. The beneficial effects are as follows: the present application can satisfy the packing sand prevention of a large displacement and high sand ratio stratum with a small casing inner diameter and limited internal space of the packing tool, the packing is carried out by using an oil casing annulus, the flow area is larger, and the structure of the present application is simpler, the construction is safer and more convenient.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, and in particular to a small casing gravel filling sand control tool and its usage method. Background Technology

[0002] For sandstone reservoirs producing sand, sand production during oil and gas well extraction can lead to well blockage, reduced or halted production, increased erosion of surface and downhole equipment, casing damage, and well abandonment. Therefore, sand control technologies are necessary for these reservoirs. Gravel packing sand control, due to its long-lasting effectiveness and high permeability, has become the dominant technology in a series of sand control techniques. Among these, the packing tool is the key to implementing gravel packing sand control.

[0003] Currently, conventionally used packing tools all involve carrying proppant through the tubing and inside the packing tool, then using the tool's conversion channel to enter the target layer and the annulus for packing. This type of packing tool can meet the requirements of high-volume, high-sand-ratio packing and sand control technology in large-diameter casing wells of 7 inches and above. However, for oil and gas wells with casing of 5-1 / 2 inches or less, packing tools using this structural principle have the following shortcomings due to their complex structure:

[0004] (1) The casing has a small inner diameter and the internal space of the filling tool is limited, which cannot meet the requirements of large displacement, high sand ratio formation squeezing or fracturing filling for sand prevention.

[0005] (2) The setting piston of the filling tool is small, making it difficult to meet the requirements of high-pressure sealing and anchoring. In particular, as most oilfields enter the middle and late stages of development, in order to increase reserves and production and save development costs, using existing old wells to drill sidetrack wells has become the mainstream of oilfield development in the middle and late stages. For this type of sidetrack well, under the condition of small wellbore, the setting force of small-diameter filling tools is small, the compression rubber sleeve is difficult to effectively set, the annular sealing pressure difference is low, and sand is easy to get stuck in the tubing string during the filling and sand control process, leading to major workover accidents. Moreover, due to the small size of the sidetrack wellbore, the operation is limited, which can easily lead to the scrapping of the sidetrack well.

[0006] (3) In addition, conventional filling tools adopt a mechanical release method of rotation and inversion. The main reason is that if hydraulic release is used, during the filling and sand control squeezing construction process, the squeezing pressure may fluctuate or become abnormal, leading to premature release. This would cause the sealing fit between the inner and outer tubing of the filling and sand control to fail, and the squeezing slurry would enter the gap between the inner and outer tubing of the sand control, causing sand to get stuck in the inner tubing of the sand control and resulting in a major well workover operation. However, this mechanical release method presents a problem of difficulty in releasing the tools during filling and sand control operations in complex wells such as medium-deep wells, highly deviated wells, and horizontal wells. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned deficiencies in the existing technology by providing a small casing gravel filling sand control tool and its usage method. This tool can meet the requirements of filling and sand control in high-volume, high-sand-ratio formations with small casing inner diameters and limited internal space of the filling tool. It utilizes the annulus of the casing for filling, resulting in a larger flow area. Furthermore, the structure of this invention is simpler, and the construction is safer and more convenient.

[0008] The present invention relates to a small-casing gravel filling sand control tool, the technical solution of which includes an upper connector and an inner tube, as well as a locking block, ball seat, shear pin, outer tube, cylinder liner, upper pressure cap, piston, winding wire, support rib, spring, retaining ring, inner lower connector, circulating steel ball, lower pressure cap, lower connector, screen tube, plug, and flushing tube.

[0009] The outer tube, upper pressure cap, winding wire, support rib, lower pressure cap, lower connector, screen tube, and plug constitute the filling outer tube part. The outer wall of the outer tube has multiple liquid passage holes, and winding wire is wound on the outer wall. One or more support ribs are provided between the winding wire and the outer wall of the outer tube. The upper pressure cap is installed on the upper side and the lower pressure cap is installed on the lower side. The lower end of the outer tube is connected to the screen tube through the lower connector, and the lower end of the screen tube is installed with a plug.

[0010] The locking block, ball seat, shear pin, cylinder liner, inner tube, piston, spring, inner lower connector, circulating steel ball, and punch tube constitute the inner tube filling part.

[0011] A cylinder liner is installed at the upper end of the inner tube, and an upper connector is connected to the upper end of the cylinder liner. The lower end of the inner tube is connected to a flushing pipe through an inner lower connector. Multiple well-washing holes are provided in the upper part of the inner tube. A piston and a spring are provided between the cylinder liner and the outside of the well-washing holes of the inner tube, and multiple circulation well-washing holes are provided on the cylinder liner. A circulation steel ball is installed at the necking part of the inner cavity of the inner lower connector. The outer wall of the upper connector is connected to the upper inner wall of the outer tube through a locking block and a shear pin, and a ball seat is installed in the inner cavity of the upper connector.

[0012] Preferably, a docking ring empty sealing head is installed at the upper end of the outer tube. The docking ring empty sealing head includes a retrieval release head and a double-sided positive feedback locking ring. The retrieval release head has a cylindrical structure with an inner diameter larger than the outer diameter of the outer tube and an outer diameter smaller than the inner diameter of the sleeve. A groove is machined on the inner wall of the retrieval release head, and a first one-way sawtooth thread is machined in the groove. Multiple sets of double-sided positive feedback locking rings are installed on the first one-way sawtooth thread.

[0013] Preferably, the double-sided positive feedback locking ring has a through groove parallel to the axis in the circumferential direction. The outer wall of the double-sided positive feedback locking ring is machined with a second one-way sawtooth thread, and the inner wall is machined with a third one-way sawtooth thread. The third one-way sawtooth thread cooperates with the one-way thread on the outer side of the outer tube to form a one-way movement function of moving downward and locking upward.

[0014] Preferably, the second unidirectional sawtooth thread on the outer wall of the aforementioned double-sided positive feedback locking ring engages with the first unidirectional sawtooth thread on the inner wall of the retrieval release head to form a unidirectional movement function that moves downward and locks upward.

[0015] Preferably, the thread clearance between the second unidirectional sawtooth thread on the outer wall of the aforementioned double-sided positive feedback locking ring and the first unidirectional sawtooth thread on the inner wall of the retrieval release head is greater than the tooth height of the third unidirectional sawtooth thread on the inner wall.

[0016] Preferably, the upper part of the above-mentioned retrieval and release head is provided with a shear pin mounting hole, and a transition joint is connected by installing retrieval and release shear pins. The upper end of the transition joint is connected to the release packer through a short section.

[0017] Preferably, a retaining ring is installed between the lower end of the inner tube and the inner lower connector.

[0018] The method for using the small casing gravel filling sand control tool mentioned in this invention includes the following steps:

[0019] 1. Safe lowering: The small casing gravel filling sand control tool is lowered into the casing through the tubing. Because the small casing gravel filling sand control tool has unidirectional flow performance from the inside to the outside, and the screen pipe connected at the bottom has the performance of internal and external communication, the internal and external pressures are kept consistent during the lowering of the small casing gravel filling sand control tool, thus ensuring the safe lowering of the tubing string.

[0020] 2. Formation filling and sand control: Close the tubing gate valve at the wellhead, and inject the sand-carrying fluid and proppant into the well through the annulus between the tubing and the casing. The fluid flows downward through the annulus between the small casing gravel filling and sand control tool and the casing, and continues downward into the formation to achieve formation filling and sand control.

[0021] 3. Reverse circulation sand control: Open the tubing gate valve and inject the sand-carrying fluid and proppant into the well through the annulus between the tubing and the casing. Flow downwards through the annulus between the small casing gravel-filled sand control tool and the casing. As the tubing channel is open, the sand-carrying fluid and proppant enter between the casing and the screen pipe. The proppant remains between the screen pipe and the casing. The sand-carrying fluid is filtered through the screen pipe and flows into the flushing pipe, then flushes open the circulating steel ball and enters the inner tubing. It then circulates upwards along the tubing to the surface, thus achieving gravel-filled sand control in the annulus between the screen pipe and the casing.

[0022] IV. Circulating Sand Flushing: The circulating sand flushing valve consists of a cylinder liner, inner tube, piston, and spring. During positive circulation well flushing, the flushing fluid is pumped downwards from the wellhead along the tubing. The flushing fluid enters the annulus between the cylinder liner and the inner tube through the flushing hole on the inner tube. The liquid pressure generated on the upper end face of the piston pushes the piston downwards. The liquid pressure overcomes the resistance of the spring, thus pushing the piston downwards and opening the circulating flushing hole on the cylinder liner. The liquid flows through the circulating flushing hole, the liquid passage hole on the outer tube, and the winding wire into the annulus between the small casing gravel filling sand control tool and the casing. Then, under hydraulic action, it circulates to the surface, flushing out the gravel remaining in the annulus between the casing and the small casing gravel filling sand control tool and the casing during the circulation filling process until it is clean.

[0023] V. Throwing, hitting and dropping, removing the filling tube section:

[0024] Drop a release steel ball into the tubing at the wellhead. The release steel ball falls along the tubing until it sinks to the ball seat. Continue to pressurize until the shear pin is cut, the ball seat moves downward, the locking block is released, and the inner tube section loses the constraint of the outer tube section and is released. Then, lift the tubing to bring the inner tube section to the surface, while the outer tube section remains downhole.

[0025] Preferably, the process also includes the following:

[0026] VI. The lower connecting ring spacer is used to seal the annulus:

[0027] At the wellhead, the release packer and the lower connecting annular packer are sent through tubing to the filling outer tubing section left downhole. The lower connecting annular packer is inserted into the annulus between the upper end of the outer tubing and the casing, with the release packer positioned above the outer tubing. After the tubing is lowered, it is pulled up until a load indicator is displayed, confirming that the third unidirectional sawtooth thread of the double-sided positive feedback locking ring of the lower connecting annular packer is correctly aligned with the unidirectional thread on the outer side of the outer tubing. Then, the ball is dropped and pressurized, the Y445 model release packer is released, the release tubing string is retrieved, and the gravel filling sand control process is completed.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The structure of the present invention is simple, without the operation of setting and sealing, and without the performance requirements of high pressure anchoring and sealing; it can complete the formation squeezing, reverse circulation filling sand prevention and circulation sand flushing operations with one tubing string and without moving the tubing string. The construction operation is convenient, safe and reliable, and there is no risk of sand jamming the tubing string; there are also very few parts left in the well, and the subsequent well repair operation is safer and more reliable.

[0030] (2) The present invention can realize the hydraulic release function, which is more adaptable to gravel filling and sand control in complex structure wells such as deep wells and horizontal wells. Moreover, when releasing, there is no direct contact with the proppant during the filling process. If the proppant is gravel, the gravel will not affect the release movement of the locking block, ensuring that the release is safe and reliable.

[0031] (3) The present invention can design a small-diameter filling tool with a smaller outer diameter, so as to achieve a larger area of ​​oil casing annulus flow, which is more conducive to filling and sand prevention with large displacement and high sand ratio, thereby effectively connecting the formation and the wellbore oil flow channel, and meeting the high efficiency and long-term production of oil and gas wells, especially small-diameter wells.

[0032] (4) The docking mechanism of the annular packer head is safe and reliable. On the one hand, it can effectively prevent the proppant in the annulus from leaking out along the annulus. On the other hand, it is easy to retrieve. After the tool is lowered to retrieve the lost packer, the retrieval string is raised until the load exceeds the load of the retrieval release shear pin. Then the docking annular packer head can be retrieved normally. Then the retrieval tool is lowered to retrieve the other parts of the well. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the upper half of the small casing gravel filling sand-proof tool of the present invention after the release steel ball is inserted;

[0034] Figure 2 This is a schematic diagram of the lower half of the small casing gravel filling sand-proof tool of the present invention after the release steel ball has been inserted;

[0035] Figure 3 This is a schematic diagram of the small casing gravel filling sand control tool of the present invention being lowered into the well without the release steel ball being deployed;

[0036] Figure 4 This is a schematic diagram of formation compression and backfilling for sand control;

[0037] Figure 5 This is a schematic diagram of reverse circulation backfilling for sand control;

[0038] Figure 6 This is a schematic diagram of the circulating well washing process;

[0039] Figure 7 This is a diagram illustrating the act of throwing and blocking a missed shot;

[0040] Figure 8 This is a schematic diagram of the well remaining after the outer pipe section is filled in following the loss;

[0041] Figure 9 This is a schematic diagram of the inner tube portion that was removed after the item was dropped.

[0042] Figure 10 This is a schematic diagram of the docking ring and the air seal head during docking;

[0043] Figure 11 yes Figure 10 An enlarged diagram of part A in the diagram;

[0044] Figure 12 This is a schematic diagram of the structure of a double-sided positive feedback locking ring;

[0045] Figure 13 This is a side view of a double-sided positive feedback locking ring;

[0046] Figure 14 yes Figure 13 An enlarged schematic diagram of part B in the diagram;

[0047] In the diagram: 1. Upper connector; 2. First sealing ring; 3. Release steel ball; 4. Locking block; 5. Ball seat; 6. Shear pin; 7. Second sealing ring; 8. Outer tube; 9. Cylinder liner; 10. Third sealing ring; 11. Inner tube; 12. Upper pressure cap; 13. Piston; 14. Wire winding; 15. Support rib; 16. Fourth sealing ring; 17. Fifth sealing ring; 18. Spring; 19. Sixth sealing ring; 20. Retaining ring; 21. Inner lower connector; 22. Circulating steel ball; 23. Lower pressure cap; 24. Lower connector; 25. Retrieval release head. 25. Double-sided positive feedback locking ring; 26. Salvage release shear pin; 27. Transition joint; 28. Release packer; 29. ​​Screen pipe; 30. Threaded plug; 31. Flushing pipe; 32. Casing; 33. Tubing; 34. Fluid passage hole; 8.1. One-way thread; 8.2. Circulation well washing hole; 9.1. Well washing hole; 11.1. Limiting step; 11.2. First one-way sawtooth thread; 25.1. Through groove; 26.1. Second one-way sawtooth thread; 26.2. Third one-way sawtooth thread; 26.3. Detailed Implementation

[0048] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0049] Example 1, referring to Figures 1-14 The present invention relates to a small-casing gravel filling sand-control tool, comprising an upper connector 1 and an inner tube 11, and further comprising a locking block 4, a ball seat 5, a shear pin 6, an outer tube 8, a cylinder liner 9, an upper pressure cap 12, a piston 13, a winding wire 14, a support rib 15, a spring 18, a retaining ring 20, an inner lower connector 21, a circulating steel ball 22, a lower pressure cap 23, a lower connector 24, a screen tube 30, a plug 31, and a flushing tube 32.

[0050] The outer tube 8, upper pressure cap 12, winding wire 14, support rib 15, lower pressure cap 23, lower connector 24, screen tube 30 and plug 31 constitute the filling outer tube part. The outer wall of the outer tube 8 is distributed with multiple liquid passage holes 8.1. The winding wire 14 is wound on the outer wall. One or more support ribs 15 are provided between the winding wire 14 and the outer wall of the outer tube 8. The upper pressure cap 12 is installed on the upper side and the lower pressure cap 23 is installed on the lower side. The lower end of the outer tube 8 is connected to the screen tube 30 through the lower connector 24. The lower end of the screen tube 30 is equipped with a plug 31.

[0051] The locking block 4, ball seat 5, shear pin 6, cylinder liner 9, inner tube 11, piston 13, spring 18, inner lower connector 21, circulating steel ball 22, and punch pipe 32 constitute the filling inner tube part.

[0052] A cylinder liner 9 is installed at the upper end of the inner tube 11, and the upper end of the cylinder liner 9 is connected to the upper connector 1. The lower end of the inner tube 11 is connected to the flushing pipe 32 through the inner lower connector 21. Multiple well-washing holes 11.1 are provided in the upper part of the inner tube 11. A piston 13 and a spring 18 are provided between the cylinder liner 9 and the outside of the well-washing holes 11.1 of the inner tube 11. Multiple circulating well-washing holes 9.1 are provided on the cylinder liner 9. A circulating steel ball 22 is installed at the necking part of the inner cavity of the inner lower connector 21. The outer wall of the upper connector 1 is connected to the upper inner wall of the outer tube 8 through a locking block 4 and a shear pin 6. A ball seat 5 is installed in the inner cavity of the upper connector 1.

[0053] In addition, the outer diameter of the outer wall of the part of the inner tube 11 where the cylinder liner 9 is installed is reduced, and a limiting step 11.2 is provided on the outer wall.

[0054] Reference Figures 8-14 A docking ring empty seal head is installed at the upper end of the outer tube 8. The docking ring empty seal head includes a retrieval release head 25 and a double-sided positive feedback locking ring 26. The retrieval release head 25 has a cylindrical structure with an inner diameter larger than the outer diameter of the outer tube 8 and an outer diameter smaller than the inner diameter of the sleeve 33. A groove is machined on the inner wall of the retrieval release head 25, and a first one-way sawtooth thread 25.1 is machined in the groove. Multiple sets of double-sided positive feedback locking rings 26 are installed on the first one-way sawtooth thread 25.1.

[0055] The aforementioned double-sided positive feedback locking ring 26 has a through groove 26.1 parallel to the axis in the circumferential direction for easy installation; the outer wall of the double-sided positive feedback locking ring 26 is machined with a second one-way sawtooth thread 26.2, and the inner wall is machined with a third one-way sawtooth thread 26.3. The third one-way sawtooth thread 26.3 cooperates with the one-way thread 8.2 on the outer side of the outer tube 8 to form a one-way movement function of moving downward and locking upward.

[0056] The second one-way sawtooth thread 26.2 on the outer wall of the aforementioned double-sided positive feedback locking ring 26 engages with the first one-way sawtooth thread 25.1 on the inner wall of the retrieval release head 25 to form a one-way movement function that moves downward and locks upward.

[0057] The upper part of the above-mentioned retrieval and release head 25 is provided with a shear pin mounting hole. The transition joint 28 is connected by installing the retrieval and release shear pin 27. The upper end of the transition joint 28 is connected to the release packer 29 through a short section.

[0058] A retaining ring 20 is installed between the lower end of the inner tube 11 and the inner lower connector 21. When the liquid flows upward during the circulating sand flushing, the circulating steel ball 22 moves upward, and the retaining ring 20 restricts the position of the circulating steel ball 22.

[0059] In addition, a first sealing ring 2 and a second sealing ring 7 are installed between the ball seat 5 and the upper connector 1, a third sealing ring 10 is installed between the cylinder liner 9 and the inner tube 11, a fourth sealing ring 16 and a fifth sealing ring 17 are installed on the outside of the piston 13, and a sixth sealing ring 19 is installed between the inner tube 11 and the inner lower connector 21.

[0060] The method of using the small casing gravel filling sand control tool mentioned in this invention includes the following steps:

[0061] I. Safe Entry: Refer to Figure 3 The small casing gravel filling sand control tool is lowered into the casing 33 through the tubing 34. Since the small casing gravel filling sand control tool has a unidirectional flow performance from the inside to the outside, and the screen pipe 30 connected at the bottom has the performance of internal and external communication, the internal and external pressures are kept consistent during the lowering of the small casing gravel filling sand control tool, thus ensuring the safe lowering of the tubing string.

[0062] II. Sand Control Through Formation Backfilling: Refer to Figure 4 The tubing gate valve at the wellhead is closed, and the sand-carrying fluid and proppant are injected into the well through the annulus between the tubing 34 and the casing 33. The fluid flows downward through the annulus between the small casing gravel-filled sand control tool and the casing 33, and continues to descend into the formation to achieve formation filling and sand control.

[0063] III. Reverse circulation backfilling for sand control: Refer to Figure 5 The tubing gate is opened, and the sand-carrying fluid and proppant are injected into the well through the annulus between the tubing 34 and the casing 33. The fluid flows downward through the annulus between the small casing gravel-filled sand control tool and the casing 33. As the tubing 34 is open, the sand-carrying fluid and proppant enter between the casing 33 and the screen pipe 30. The proppant remains between the screen pipe 30 and the casing 33. The sand-carrying fluid is filtered through the screen pipe 30 and flows into the flushing pipe 32, then flushes open the circulating steel ball 22 and enters the inner tube 11. It then flows upward along the tubing 34 back to the surface, thus achieving gravel-filled sand control in the annulus between the screen pipe 30 and the casing 33.

[0064] IV. Circulating sand flushing: Refer to Figure 6The circulating sand flushing valve consists of a cylinder liner 9, an inner tube 11, a piston 13, and a spring 18. During the forward circulation well flushing, the flushing fluid is pumped downwards from the wellhead along the tubing 34. The flushing fluid enters the annulus between the cylinder liner 9 and the inner tube 11 through the flushing hole 11.1 on the inner tube 11. The liquid pressure generated on the upper end face of the piston 13 pushes the piston 13 downwards. The liquid pressure overcomes the resistance of the spring 18, thus pushing the piston 13 downwards and opening the circulating flushing hole 9.1 on the cylinder liner 9. Liquid flows through the circulating flushing hole 9.1, the liquid passage hole 8.1 on the outer tube 8, and the winding wire 14 into the annulus between the small casing gravel filling sand control tool and the casing 33. Then, under the action of hydraulic pressure, it circulates to the surface, flushing out the gravel remaining in the annulus between the casing and the small casing gravel filling sand control tool and the casing 33 during the circulation filling process until it is clean.

[0065] V. Throwing, hitting and dropping, removing the filling tube section:

[0066] Reference Figure 7 At the wellhead, a release steel ball 3 is dropped into the tubing 34. The release steel ball 3 falls along the tubing 34 until it sinks to the ball seat 5. Pressure is continued until the shear pin 6 is sheared, the ball seat 5 moves downward, the locking block 4 is released, and the inner tube part loses the constraint of the outer tube part and is released. Then, the tubing 34 is lifted up to bring the inner tube part to the surface, while the outer tube part remains downhole.

[0067] In addition, the present invention also includes the following processes:

[0068] VI. The lower connecting ring spacer is used to seal the annulus:

[0069] Reference Figures 8-11 At the wellhead, the release packer 29 and the lower connecting annular packer head are sent to the filling outer tubing section left downhole via tubing 34. The lower connecting annular packer head is inserted into the annulus between the upper end of the outer tubing 8 and the casing 33, with the release packer 29 positioned above the outer tubing 8. After pressing down tubing 34, it is pulled up until a load indicator is displayed to confirm that the third unidirectional sawtooth thread 26.3 of the double-sided positive feedback locking ring 26 of the lower connecting annular packer head is correctly connected to the unidirectional thread 8.2 on the outside of the outer tubing 8. Then, the ball is dropped and pressurized again, the Y445 model release packer 29 is released, the release tubing string is retrieved, and the gravel filling sand control process is completed.

[0070] Example 2: A small-casing gravel filling sand-control tool mentioned in this invention includes an upper connector 1 and an inner tube 11, as well as a locking block 4, a ball seat 5, a shear pin 6, an outer tube 8, a cylinder liner 9, an upper pressure cap 12, a piston 13, a winding wire 14, a support rib 15, a spring 18, a retaining ring 20, an inner lower connector 21, a circulating steel ball 22, a lower pressure cap 23, a lower connector 24, a screen tube 30, a plug 31, and a flushing tube 32.

[0071] The outer tube 8, upper pressure cap 12, winding wire 14, support rib 15, lower pressure cap 23, lower connector 24, screen tube 30 and plug 31 constitute the filling outer tube part. The outer wall of the outer tube 8 is distributed with multiple liquid passage holes 8.1. The winding wire 14 is wound on the outer wall. One or more support ribs 15 are provided between the winding wire 14 and the outer wall of the outer tube 8. The upper pressure cap 12 is installed on the upper side and the lower pressure cap 23 is installed on the lower side. The lower end of the outer tube 8 is connected to the screen tube 30 through the lower connector 24. The lower end of the screen tube 30 is equipped with a plug 31.

[0072] The locking block 4, ball seat 5, shear pin 6, cylinder liner 9, inner tube 11, piston 13, spring 18, inner lower connector 21, circulating steel ball 22, and punch pipe 32 constitute the filling inner tube part.

[0073] A cylinder liner 9 is installed at the upper end of the inner tube 11, and the upper end of the cylinder liner 9 is connected to the upper connector 1. The lower end of the inner tube 11 is connected to the flushing pipe 32 through the inner lower connector 21. Multiple well-washing holes 11.1 are provided in the upper part of the inner tube 11. A piston 13 and a spring 18 are provided between the cylinder liner 9 and the outside of the well-washing holes 11.1 of the inner tube 11. Multiple circulating well-washing holes 9.1 are provided on the cylinder liner 9. A circulating steel ball 22 is installed at the necking part of the inner cavity of the inner lower connector 21. The outer wall of the upper connector 1 is connected to the upper inner wall of the outer tube 8 through a locking block 4 and a shear pin 6. A ball seat 5 is installed in the inner cavity of the upper connector 1.

[0074] The difference from Example 1 is:

[0075] In this embodiment, the thread clearance between the second unidirectional sawtooth thread 26.2 on the outer wall of the double-sided positive feedback locking ring 26 and the first unidirectional sawtooth thread 25.1 on the inner wall of the retrieval release head 25 is greater than the tooth height of the third unidirectional sawtooth thread 26.3 on the inner wall.

[0076] The above description is merely a partial preferred embodiment of the present invention. Any person skilled in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A small-casing gravel filling sand control tool, comprising an upper connector (1) and an inner tube (11), characterized in that: It also includes a locking block (4), a ball seat (5), a shear pin (6), an outer tube (8), a cylinder liner (9), an upper pressure cap (12), a piston (13), a winding wire (14), a support rib (15), a spring (18), a retaining ring (20), an inner lower connector (21), a circulating steel ball (22), a lower pressure cap (23), a lower connector (24), a screen tube (30), a plug (31), and a punch tube (32). The outer tube (8), upper pressure cap (12), winding wire (14), support rib (15), lower pressure cap (23), lower connector (24), sieve tube (30) and plug (31) form the filling outer tube part. The outer wall of the outer tube (8) is distributed with multiple liquid passage holes (8.1). The winding wire (14) is wound on the outer wall. One or more support ribs (15) are provided between the winding wire (14) and the outer wall of the outer tube (8). The upper pressure cap (12) is installed on the upper side and the lower pressure cap (23) is installed on the lower side. The lower end of the outer tube (8) is connected to the sieve tube (30) through the lower connector (24). The lower end of the sieve tube (30) is installed with plug (31). The locking block (4), ball seat (5), shear pin (6), cylinder liner (9), inner tube (11), piston (13), spring (18), inner lower connector (21), circulating steel ball (22), and punch (32) constitute the filling inner tube part. The upper end of the inner tube (11) is fitted with a cylinder liner (9), the upper end of the cylinder liner (9) is connected to the upper connector (1), and the lower end of the inner tube (11) is connected to the flushing pipe (32) through the inner lower connector (21). Multiple well-washing holes (11.1) are provided in the upper part of the inner tube (11). A piston (13) and a spring (18) are provided between the cylinder liner (9) and the outside of the well-washing holes (11.1) of the inner tube (11). Multiple circulating well-washing holes (9.1) are provided on the cylinder liner (9). A circulating steel ball (22) is installed at the inner cavity neck of the inner lower connector (21). The outer wall of the upper connector (1) is connected to the upper inner wall of the outer tube (8) through a locking block (4) and a shear pin (6). A ball seat (5) is installed in the inner cavity of the upper connector (1).

2. The small casing gravel filling sand control tool according to claim 1, characterized in that: A docking ring empty sealing head is installed at the upper end of the outer tube (8). The docking ring empty sealing head includes a retrieval release head (25) and a double-sided positive feedback locking ring (26). The retrieval release head (25) is a cylindrical structure with an inner diameter larger than the outer diameter of the outer tube (8) and an outer diameter smaller than the inner diameter of the sleeve (33). A groove is machined on the inner wall of the retrieval release head (25), and a first one-way sawtooth thread (25.1) is machined in the groove. Multiple sets of double-sided positive feedback locking rings (26) are installed on the first one-way sawtooth thread (25.1).

3. The small casing gravel filling sand control tool according to claim 2, characterized in that: The double-sided positive feedback locking ring (26) has a through groove (26.1) parallel to the axis in the circumferential direction. The outer wall of the double-sided positive feedback locking ring (26) is machined with a second one-way sawtooth thread (26.2), and the inner wall is machined with a third one-way sawtooth thread (26.3). The third one-way sawtooth thread (26.3) cooperates with the one-way thread (8.2) on the outer side of the outer tube (8) to form a one-way movement function that moves downward and locks upward.

4. The small casing gravel filling sand control tool according to claim 3, characterized in that: The second one-way sawtooth thread (26.2) on the outer wall of the double-sided positive feedback locking ring (26) cooperates with the first one-way sawtooth thread (25.1) on the inner wall of the retrieval release head (25) to form a one-way movement function that moves downward and locks upward.

5. The small casing gravel filling sand control tool according to claim 4, characterized in that: The thread clearance between the second unidirectional sawtooth thread (26.2) on the outer wall of the double-sided positive feedback locking ring (26) and the first unidirectional sawtooth thread (25.1) on the inner wall of the salvage release head (25) is greater than the tooth height of the third unidirectional sawtooth thread (26.3) on the inner wall.

6. The small casing gravel filling sand control tool according to claim 5, characterized in that: The upper part of the salvage release head (25) is provided with a shear pin mounting hole. The transition joint (28) is connected by installing the salvage release shear pin (27). The upper end of the transition joint (28) is connected to the release packer (29) through a short section.

7. The small casing gravel filling sand control tool according to claim 6, characterized in that: A retaining ring (20) is installed between the lower end of the inner tube (11) and the inner lower connector (21).

8. The method of using the small casing gravel filling sand control tool according to claim 7, characterized in that: Includes the following processes:

1. Safe lowering: The small casing gravel filling sand control tool is lowered into the casing (33) through the oil pipe (34). Since the small casing gravel filling sand control tool has a unidirectional flow performance from the inside to the outside, and the screen pipe (30) connected at the bottom has the performance of internal and external communication, the internal and external pressures are kept consistent during the lowering of the small casing gravel filling sand control tool, thus ensuring the safe lowering of the tubing string.

2. Formation filling and sand control: Close the tubing gate at the wellhead, and inject the sand-carrying fluid and proppant into the well through the annulus between the tubing (34) and the casing (33). The fluid flows downward through the annulus between the small casing gravel filling and sand control tool and the casing (33), and continues to flow downward into the formation to achieve formation filling and sand control.

3. Reverse circulation sand control: Open the tubing gate valve and inject the sand-carrying fluid and proppant into the well through the annulus between the tubing (34) and the casing (33). Flow downwards through the annulus between the small casing gravel filling sand control tool and the casing (33). As the tubing (34) channel is open, the sand-carrying fluid and proppant enter between the casing (33) and the screen pipe (30). The proppant remains between the screen pipe (30) and the casing (33). The sand-carrying fluid is filtered through the screen pipe (30) and flows into the flushing pipe (32), then flushes open the circulating steel ball (22) and enters the inner tube (11). It then flows upwards along the tubing (34) to the surface in reverse circulation, thus achieving gravel filling sand control in the annulus between the screen pipe (30) and the casing (33). IV. Circulating Sand Flushing: The circulating sand flushing valve consists of a cylinder liner (9), an inner tube (11), a piston (13), and a spring (18). During the positive circulation well flushing, the flushing fluid is pumped downwards from the wellhead along the tubing (34). The flushing fluid enters the annulus between the cylinder liner (9) and the inner tube (11) through the flushing hole (11.1) on the inner tube (11). The liquid pressure generated on the upper end face of the piston (13) pushes the piston (13) downwards. The liquid pressure overcomes the resistance of the spring (18) and thus pushes the piston. (13) Downward movement, open the circulation well-washing hole (9.1) on the cylinder liner (9), and the liquid flows through the circulation well-washing hole (9.1), the liquid passage hole (8.1) on the outer tube (8) and the winding wire (14) into the annulus between the small casing gravel filling sand control tool and the casing (33). Then, under the action of hydraulic pressure, it circulates to the ground and flushes out the gravel that remains in the annulus between the oil casing and the small casing gravel filling sand control tool and the casing (33) during the circulation filling process until it is clean. V. Throwing, hitting and dropping, removing the filling tube section: Drop a drop ball (3) into the tubing (34) at the wellhead. The drop ball (3) falls along the tubing (34) until it sinks to the ball seat (5). Continue to pressurize until the shear pin (6) is cut off. The ball seat (5) moves down and the locking block (4) is released. The inner tube is released from the constraint of the outer tube and is dropped. Then, lift it up through the tubing (34) to bring the inner tube to the surface, while the outer tube remains downhole.

9. The method of using the small casing gravel filling sand control tool according to claim 8, characterized in that: Also includes the following process: VI. The lower connecting ring spacer is used to seal the annulus: At the wellhead, the drop packer (29) and the lower docking annular packer head are sent to the filling outer tube section left downhole via tubing (34). The lower docking annular packer head is inserted into the annulus between the upper end of the outer tube (8) and the casing (33), with the drop packer (29) positioned above the outer tube (8). After the tubing (34) is lowered, it is pulled up until a load indicator is displayed. It is confirmed that the third one-way sawtooth thread (26.3) of the double-sided positive feedback locking ring (26) of the lower docking annular packer head is correctly connected to the one-way thread (8.2) on the outside of the outer tube (8). Then, the ball is dropped and pressurized again. The Y445 model drop packer (29) drops, the drop packer string is pulled out, and the gravel filling sand control process is completed.

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