Large-drift-diameter fracturing sliding sleeve system

Abstract

The invention discloses a large-drift-diameter fracturing sliding sleeve system, which relates to the technical field of oil and gas well fracturing and comprises a plurality of sliding sleeves, and each sliding sleeve comprises an outer pipe and an inner pipe arranged in the outer pipe. The outer pipe comprises a first sleeve, a second sleeve and a third sleeve which are in threaded connection in sequence; the inner pipe comprises a fourth sleeve and a fifth sleeve which are in threaded connection, the outer wall of the fourth sleeve clings to the inner wall of the second sleeve, a gap is formed between the outer wall of the fifth sleeve and the inner wall of the second sleeve, and the outer wall of the fifth sleeve clings to the inner wall of the third sleeve; a plurality of through holes are formed in the side wall of the second casing pipe in the circumferential direction in an array mode, a plurality of fracturing holes are further formed in the side wall of the second casing pipe in an array mode, the through holes are located between the first casing pipe and the fracturing holes, and shear pins are arranged in the through holes and used for fixing the fourth casing pipe. A circle of clamping groove is formed in the inner wall of the fourth sleeve and used for clamping the soluble plunger with the corresponding shape and size. According to the scheme, large-drift-diameter multi-stage staged fracturing can be achieved, the flexibility and accuracy of fracturing operation are improved, and the operation cost and complexity are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas well fracturing, and in particular to a large-diameter fracturing sleeve system. Background Art

[0002] Underground fracturing technology is an essential step in the extraction process of oil, natural gas, etc. It injects high-pressure liquid into underground rock formations to form cracks, thereby increasing the permeability of oil and gas and promoting the flow of oil and gas.

[0003] In order to achieve multi-stage fracturing, the ball-sleeve multi-stage fracturing completion technology or the pumped bridge plug multi-stage fracturing completion technology is often used. The ball-sleeve multi-stage fracturing completion technology realizes step-by-step fracturing by combining balls and ball seats of different grades. However, this technology has certain limitations. First, the size of the graded ball seats has a great influence on the number of stages and the scale of fracturing, which limits its scope of application. Second, if the wellbore design is unreasonable, it may lead to poor fracturing effect and even the risk of fracturing failure. In addition, the implementation of this technology requires a high level of technology and equipment support, which increases the complexity and cost of the project.

[0004] The pumped bridge plug multi-stage fracturing completion technology has no limit on the number of stages and can be flexibly adjusted according to actual needs. This technology can effectively improve the continuity and uniformity of fracturing by setting a bridge plug in the wellbore and using high-pressure pumping liquid for fracturing. However, this technology also faces some challenges. First, the perforation and fracturing process may affect the continuity of fracturing, thereby affecting the fracturing effect; second, the operation cycle is long, and drilling and plugging are required after completion, which increases the complexity and time cost of the project; finally, after the operation is completed, selective production or secondary fracturing is often not possible, limiting the potential for later development. Summary of the invention

[0005] To address the deficiencies in the prior art, the present invention provides a large-diameter fracturing sleeve system that can achieve large-diameter multi-stage fracturing, improve the flexibility and accuracy of fracturing operations, and reduce operating costs and complexity.

[0006] In order to achieve the purpose of the present invention, the following scheme is proposed: A large-diameter fracturing sliding sleeve system comprises a plurality of sliding sleeves, wherein the sliding sleeves comprise an outer tube and an inner tube arranged therein.

[0007] The outer tube includes a first sleeve, a second sleeve, and a third sleeve which are threadedly connected in sequence; The inner tube comprises a fourth sleeve and a fifth sleeve which are threadedly connected, the outer wall of the fourth sleeve is in close contact with the inner wall of the second sleeve, there is a gap between the outer wall of the fifth sleeve and the inner wall of the second sleeve, and the outer wall of the fifth sleeve is in close contact with the inner wall of the third sleeve; The side wall of the second casing is provided with a plurality of through holes in an array along the circumferential direction, and a plurality of fracturing holes in an array, wherein the through holes are located between the first casing and the fracturing holes, and shear pins are provided in the through holes for fixing the fourth casing; A circle of clamping grooves is arranged on the inner wall of the fourth sleeve. The inner diameter of each fourth sleeve is different and the length of the clamping grooves is different, and the clamping grooves are used to clamp soluble plungers of corresponding shapes and sizes.

[0008] The beneficial effects of the present invention are: 1. In each sliding sleeve, the inner diameter of the fourth casing is different, and the length of the slot is different. When multiple sliding sleeves are lowered into the oil and gas layer in the well, the length of the slot decreases step by step from bottom to top, and the inner diameter of the fourth casing increases step by step. For the inner diameter of the fourth casing of the two-layer sliding sleeve, the inner diameter range is 0.35mm, and for the inner diameter of the fourth casing of the ten-layer sliding sleeve, the inner diameter range is 3.5mm, realizing a large-diameter sliding sleeve.

[0009] 2. The diameter of the sliding sleeve can be maintained after fracturing is completed, which is convenient for subsequent well repair operations.

[0010] 3. No need for perforation and additional packer layers, the continuous one-trip fracturing operation not only ensures the continuity of the fracturing operation, but also shortens the operation time and saves costs.

[0011] 4. The sliding sleeve can effectively avoid casing deformation caused by weakening of the casing due to perforation.

[0012] 5. The sliding sleeve is opened and closed by a soluble plunger. When the sliding sleeve is opened and fracturing is carried out, only the soluble plunger remains in the wellbore, which can effectively reduce construction accidents.

[0013] 6. It avoids the problem of water coming out of the oil layer after conventional casing perforation. The closing tool can be lowered into the coiled tubing to close the sliding sleeve at the water outlet position, which is simple and convenient to operate.

[0014] 7. The use of the sliding sleeve greatly increases the integrity of the casing. The characteristic of the sliding sleeve that can be opened and closed multiple times can effectively avoid the conventional one-time mining method and reserve working space for later production layer processing.

[0015] 8. The elastic sheet soluble plunger is easy to operate and highly reliable.

[0016] 9. Even if the casing is slightly deformed, it will not affect the permeability of the soluble plunger and the subsequent fracturing construction.

[0017] 10. The soluble plunger can be directly placed without the assistance of other equipment, which greatly saves costs.

[0018] 11. The pressure-bearing level of the soluble plunger is 70MPa. It bears pressure in two ways: one is through the slot of the elastic sheet and the sliding sleeve, and the other is through the back seat and the fourth sleeve.

[0019] 12. Pure mechanical structure, without any electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An external view of the sleeve is shown; Figure 2 A first sleeve structure diagram is shown; Figure 3 A second sleeve structure diagram is shown; Figure 4 A third sleeve structure diagram is shown; Figure 5 A fourth casing structure diagram is shown; Figure 6 A fifth casing structure diagram is shown; Figure 7 A cross-sectional view of the sleeve is shown; Figure 8 for Figure 7 A partial enlarged view of the middle part; Fig. 9 for Figure 7 A partial enlarged view of point B in the middle; Fig.10 for Figure 7 A partial enlarged view of point C in the middle; Fig.11 for Figure 7 A partial enlarged view of point D in the middle; Fig.12 A diagram of a soluble plunger structure is shown; Fig.13 A cross-sectional view of a soluble plunger is shown; Fig.14 A top view of a soluble plunger is shown; Fig.15 An overall cross-sectional view showing the soluble plunger stuck in the inner tube; Fig.16 The structural diagram when the soluble plunger is stuck in the inner tube is shown; Fig.17 A plan view is shown of the soluble plunger when it is stuck in the inner tube. DETAILED DESCRIPTION

[0021] like Figure 1 As shown, this embodiment provides a large-diameter fracturing sleeve system, including a plurality of sleeves, each of which includes an outer tube and an inner tube arranged inside the outer tube.

[0022] like Figure 1-Figure 11As shown, the outer tube includes a first sleeve 1, a second sleeve 2, and a third sleeve 3 that are threadedly connected in sequence, and the inner tube includes a fourth sleeve 4 and a fifth sleeve 5 that are threadedly connected. The outer wall of the fourth sleeve 4 is in close contact with the inner wall of the second sleeve 2. There is a gap 6 between the outer wall of the fifth sleeve 5 and the inner wall of the second sleeve 2. The outer wall of the fifth sleeve 5 is in close contact with the inner wall of the third sleeve 3. The side wall of the second sleeve 2 is arrayed with a plurality of through holes 21 in the circumferential direction, and is also arrayed with a plurality of fracturing holes 22. The through hole 21 is located between the first sleeve 1 and the fracturing hole 22, and a shear pin is arranged in the through hole 21. , which is used to fix the fourth casing 4. The side wall of the fourth casing 4 serves to close the fracturing hole 22. When the inner tube is pressurized, the shear pins are cut off, the inner tube loses the restriction of the shear pins, and moves toward the third casing 3, the gap 6 is used to avoid the fourth casing 4. During this process, the fracturing hole 22 is gradually opened. The inner wall of the fourth casing 4 is provided with a circle of grooves 46. The grooves 46 are acute-angled toward one end of the fifth casing 5. Each fourth casing 4 has a different inner diameter and a different length of the grooves 46, which are used to clamp soluble plungers of corresponding shapes and sizes.

[0023] About the specific connection method of the outer tube and the inner tube: like Figure 1-Figure 11 As shown, the first end of the first sleeve 1 is provided with an internal thread, the second end of the first sleeve 1 is provided with an external thread and a smooth section, the external thread of the first sleeve 1 is connected to the first end of the second sleeve 2, the smooth section of the first sleeve 1 is in close contact with the inner wall of the second sleeve 2, the end surface of the first end of the fourth sleeve 4 is connected to the end surface of the smooth section, the inner wall of the second end of the fourth sleeve 4 is threadedly connected to the fifth sleeve 5, the first end of the third sleeve 3 is provided with an external thread and a smooth section, the second end of the third sleeve 3 is provided with an internal thread, the external thread of the third sleeve 3 is connected to the second end of the second sleeve 2, and the smooth section of the third sleeve 3 is in close contact with the inner wall of the second sleeve 2.

[0024] like Figure 1-Figure 5 As shown, the outer wall of the smooth section of the first sleeve 1 is provided with a first annular groove 11, starting from the first end of the fourth sleeve 4, the outer wall of the fourth sleeve 4 is sequentially provided with a second annular groove 42, a third annular groove 43, and a fourth annular groove 44, and the outer wall of the smooth section of the third sleeve 3 is provided with a sixth annular groove 31, and a plurality of through holes 21 correspond to the third annular groove 43, and the shear pins are installed in the through holes 21 and the third annular groove 43. Except for the third annular groove 43, the first annular groove 11, the second annular groove 42, the fourth annular groove 44, and the sixth annular groove 31 are all provided with sealing rings.

[0025] like Fig.10As shown, the inner wall of the second sleeve 2 is provided with two annular shear grooves 23, and the shear grooves 23 are located at the gap 6. The outer wall of the fourth sleeve 4 is provided with a fifth annular groove 45, and two shear C rings 451 are arranged in the fifth annular groove 45. When the inner tube loses the restriction of the shear pin and moves toward the third sleeve 3, the shear groove 23 is used to accommodate the corresponding shear C ring 451. The shear C ring 451 has two functions: ① When the inner tube moves toward the third sleeve 3, the shear C ring 451 will move with the inner tube into the shear groove 23 of the body; ② The shear C ring 451 has a certain shear value. When the sliding sleeve needs to be closed again, a shear value higher than the shear C ring 451 can be applied to the inner tube.

[0026] The fracturing sleeve system is used as follows: Assemble the outer tube and the inner tube together to form a sliding sleeve, and assemble the plurality of sliding sleeves in sequence according to a specific order; Lower multiple sliding sleeves into the oil and gas layer in the well, with the third casing 3 facing downwards, and the length of the slot 46 of each sliding sleeve is different, and the length of the slot 46 decreases step by step from bottom to top; After cementing, the soluble plungers are lowered in a specific order and stuck in the corresponding sliding sleeves; The soluble plunger is pressurized, the shear pin is cut off, and after the inner tube loses the restriction of the shear pin, the inner tube and the soluble plunger move together toward the third casing 3. After reaching a specific position, the shear C ring 451 pops open and is positioned in the corresponding shear groove 23. In this process, the fracturing hole 22 is gradually opened; Start multi-layer staged fracturing; The soluble plunger is made of soluble metal material, such as magnesium-aluminum alloy. After fracturing is completed, the soluble plunger is dissolved to achieve full bore.

[0027] In summary, this process technology is a multi-layer segmented fracturing completion technology combined with a switchable sleeve. This technology uses a switchable sleeve to be selectively placed at the oil layer position. After cementing is completed, a soluble plunger is put in to start from the bottom layer to achieve hanging, and the sleeve is opened by pressurizing the inner tube to expose the fracturing hole 22. This fracturing completion system can be equipped with multiple sleeves according to the production layer of the oil reservoir to achieve multi-layer fracturing production. This technology can be applied to any well put into production using fracturing measures. In addition, according to the needs of future production, the contradiction between the oil reservoir layers can be adjusted to improve the utilization rate of the oil reservoir.

[0028] The structure of the soluble plunger is as follows: Figure 12-14As shown, the soluble plunger is hollow inside and includes a front seat 73, an elastic tube 72 and a rear seat 71 which are threadedly connected in sequence. The end faces of the front seat 73 and the rear seat 71 are both closed. The outer wall of the elastic tube 72 is arrayed with a plurality of elastic sheets 721 along the circumferential direction. The end of the elastic sheet 721 facing the front seat 73 is an acute-angle structure for hooking the corresponding slot 46. The other end of the elastic sheet 721 is an obtuse-angle structure. A strip groove 722 is provided on each side of the elastic sheet 721. The strip groove 722 runs through the side wall of the elastic tube 72. As mentioned above, the end of the slot 46 facing the fifth sleeve 5 is an acute-angle structure. The shape and length of the slot 46 must be adapted to the corresponding elastic sheet 721 in order to clamp the corresponding soluble plunger. Therefore, the length of the elastic sheet 721 must be smaller than the length of the corresponding slot 46.

[0029] like Figure 12-14 As shown, the outer wall of the elastic tube 72 is also arrayed with a plurality of elastic blocks 723 along the circumferential direction. The number and position of the elastic blocks 723 and the elastic sheets 721 correspond one to one. The elastic block 723 is located between the elastic sheet 721 and the front seat 73. One end of the elastic block 723 facing the front seat 73 is an obtuse angle structure, and the other end is also an obtuse angle structure. One end of the strip groove 722 is located between the elastic block 723 and the front seat 73. The function of the strip groove 722 is to ensure that the elastic tube 72 can be deformed. A circle of avoidance grooves 47 are provided on the inner wall of the fourth sleeve 4. When the soluble plunger is stuck in the corresponding slot 46, the elastic block 723 is located in the avoidance groove 47.

[0030] like Figure 15-17 As shown, when the soluble plunger is stuck in the corresponding slot 46, the front seat 73 is located in the fifth casing 5, and the rear seat 71 is located in the first casing 1 and the fourth casing 4. When the soluble plunger is lowered into the well, in order to ensure that the soluble plunger can smoothly pass through the unmatched sliding sleeve and finally reach the matched sliding sleeve, the outer diameter of the rear seat 71 should be larger than the inner diameter of the corresponding fourth casing 4 so that the rear seat 71 can be stuck on the corresponding fourth casing 4.

[0031] In order to lower the soluble plunger to a specific position, as mentioned above: multiple sleeves are lowered into the oil and gas layer in the well, and the length of the slot 46 of each sleeve decreases step by step from bottom to top. Therefore, when the soluble plunger is released, the soluble plunger with the largest elastic sheet 721 and the smallest outer diameter of the rear seat 71 is released first, and then the soluble plungers with the elastic sheet 721 length decreasing step by step and the outer diameter of the rear seat 71 increasing step by step are released in turn. The inner diameter of the fourth casing 4 increases by 0.35mm, that is, the range of two layers is 0.35mm, and the range of ten layers is 3.5mm.

[0032] The soluble plunger is subjected to pressure in two ways: one is through the elastic sheet 721 and the slot 46 of the sliding sleeve, and the other is through the rear seat 71 and the fourth sleeve.

[0033] In summary, this embodiment achieves precise control of multi-layer fracturing of oil and gas wells by adjusting the size of the soluble plunger and the length of the elastic sheet 721. When the size of the soluble plunger meets the passing condition, the soluble plunger will pass through the sleeve smoothly. When the size of the soluble plunger meets the sealing condition, the soluble plunger will be sealed at the sleeve. When the soluble plunger is seated in the sleeve, the displacement is increased, and the high-displacement soluble plunger is used to seal the soluble plunger. The shear force of the soluble plunger sealing start is adjustable (1-3 tons), thereby achieving layered fracturing of oil and gas wells. This design not only improves the flexibility and accuracy of fracturing operations, but also reduces operating costs and complexity.

[0034] The soluble plunger provided in this embodiment has the following performance advantages: ①Adapt to different temperature ranges of 38℃~178℃ (100F-350F); ② A variety of material combination designs can be provided to meet the requirements of different blocks; ③ The pressure level is 70MPa (10000PSI), the design is simple, and the integrated anti-premature setting design can be set in the sliding sleeve at a specific position; ④100% metal soluble material, completely dissolved within 5 days (the dissolution time can be adjusted according to site needs); ⑤ Fine treatment of metal surface, surface coating treatment, acid-resistant, water-soluble, anti-corrosion surface spraying to adapt to the construction wells of acid injection immersion; ⑥Applicable to all current casing steel grades (P110 / 125 / 140, etc.); ⑦ The maximum inner diameter design is conducive to flowback after fracturing without affecting production.

[0035] The above embodiments are only used to illustrate the technical ideas and features of the present invention, and are not intended to be the only or limit the present invention. It should be understood by those skilled in the art that various changes or equivalent substitutions made to the present invention without departing from the scope of the present invention all fall within the scope of protection of the present invention.

Claims

1. A large-diameter fracturing sleeve system, characterized in that: It comprises a plurality of sliding sleeves, wherein the sliding sleeves comprise an outer tube and an inner tube arranged therein; The outer tube comprises a first sleeve (1), a second sleeve (2), and a third sleeve (3) which are threadedly connected in sequence; The inner tube comprises a fourth sleeve (4) and a fifth sleeve (5) which are threadedly connected, the outer wall of the fourth sleeve (4) is in close contact with the inner wall of the second sleeve (2), a gap (6) is provided between the outer wall of the fifth sleeve (5) and the inner wall of the second sleeve (2), and the outer wall of the fifth sleeve (5) is in close contact with the inner wall of the third sleeve (3); The side wall of the second casing (2) is provided with a plurality of through holes (21) in an array along the circumferential direction, and also is provided with a plurality of fracturing holes (22) in an array, the through holes (21) being located between the first casing (1) and the fracturing holes (22), and a shear pin is provided in the through hole (21) for fixing the fourth casing (4); A circle of clamping grooves (46) are provided on the inner wall of the fourth sleeve (4); each fourth sleeve (4) has a different inner diameter and a different length of the clamping grooves (46), and is used to clamp soluble plungers of corresponding shapes and sizes.

2. The large-diameter fracturing sleeve system according to claim 1, characterized in that: The first end of the first sleeve (1) is provided with an internal thread, and the second end is provided with an external thread and a smooth section. The external thread of the first sleeve (1) is connected to the second sleeve (2), and the smooth section of the first sleeve (1) is in close contact with the inner wall of the second sleeve (2). The end surface of the first end of the fourth sleeve (4) is in contact with the end surface of the smooth section. The inner wall of the second end of the fourth sleeve (4) is threadedly connected to the fifth sleeve (5). The first end of the third sleeve (3) is provided with an external thread and a smooth section, and the second end is provided with an internal thread. The external thread of the third sleeve (3) is connected to the second sleeve (2), and the smooth section of the third sleeve (3) is in close contact with the inner wall of the second sleeve (2).

3. The large-diameter fracturing sleeve system according to claim 2, characterized in that: The smooth section outer wall of the first sleeve (1) is provided with a first annular groove (11); starting from the first end of the fourth sleeve (4), the outer wall of the fourth sleeve (4) is provided with a second annular groove (42), a third annular groove (43), and a fourth annular groove (44) in sequence; the smooth section outer wall of the third sleeve (3) is provided with a sixth annular groove (31); a plurality of through holes (21) correspond to the third annular groove (43); and except for the third annular groove (43), sealing rings are provided in the remaining annular grooves.

4. The large-diameter fracturing sleeve system according to claim 1, characterized in that: The inner wall of the second sleeve (2) is provided with two annular shear grooves (23), the shear grooves (23) being located at the gap (6); the outer wall of the fourth sleeve (4) is provided with a fifth annular groove (45), two shear C-rings (451) being arranged in the fifth annular groove (45); when the inner tube loses the restriction of the shear pin and moves toward the third sleeve (3), the shear grooves (23) are used to accommodate the corresponding shear C-rings (451).

5. The large-diameter fracturing sleeve system according to claim 1, characterized in that: The end of the clamping groove (46) facing the fifth sleeve (5) is in an acute angle structure.

6. The large-diameter fracturing sleeve system according to claim 5, characterized in that: The soluble plunger is hollow inside and comprises a front seat (73), an elastic tube (72) and a rear seat (71) which are threadedly connected in sequence. The outer wall of the elastic tube (72) is provided with a plurality of elastic sheets (721) arranged in an array along a circumferential direction. One end of the elastic sheet (721) facing the front seat (73) is an acute-angle structure, and the other end is an obtuse-angle structure. A strip groove (722) is provided on each side of the elastic sheet (721). The strip groove (722) penetrates the side wall of the elastic tube (72). The length of the elastic sheet (721) is less than the length of the corresponding slot (46). The outer diameter of the rear seat (71) is greater than the inner diameter of the corresponding fourth sleeve (4).

7. The large-diameter fracturing sleeve system according to claim 5, characterized in that: When the soluble plunger is locked in the corresponding locking groove (46), the front seat (73) is located in the fifth sleeve (5), and the rear seat (71) is located in the first sleeve (1) and the fourth sleeve (4).

8. The large-diameter fracturing sleeve system according to claim 5, characterized in that: The outer wall of the elastic tube (72) is also provided with a plurality of elastic blocks (723) arranged in an array along the circumferential direction. The number and position of the elastic blocks (723) correspond to the elastic sheet (721) one by one. The elastic block (723) is located between the elastic sheet (721) and the front seat (73). One end of the elastic block (723) facing the front seat (73) is in an obtuse angle structure, and the other end is also in an obtuse angle structure. One end of the strip groove (722) is located between the elastic block (723) and the front seat (73).

9. The large-diameter fracturing sleeve system according to claim 8, characterized in that: The inner wall of the fourth sleeve (4) is provided with a circle of avoidance grooves (47), and when the soluble plunger is clamped in the corresponding clamping groove (46), the elastic block (723) is located in the avoidance groove (47).

10. The large-diameter fracturing sleeve system according to claim 5, characterized in that: The soluble plunger is made of soluble metal material.

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