A fracturing and packing integrated tool assembly

Abstract

This invention relates to an integrated fracturing and packer tool assembly, belonging to the field of downhole tools technology for oil and gas fields. The assembly comprises, from top to bottom, an upper fracturing control unit, a sliding sleeve reset unit, and a packer unit. The upper fracturing control unit includes an upper connector, a sandblasting sliding sleeve, and a nozzle. The upper connector is connected to the upper end of the sandblasting sliding sleeve, and the nozzle is housed within the inner cavity of the sandblasting sliding sleeve. Both the sandblasting sliding sleeve and the nozzle have corresponding side holes and a controllable sealing mechanism for opening and closing the fracturing channel formed by the side holes. The sliding sleeve reset unit includes a cylinder and an elastic element disposed therein. The packer unit includes a central tube and a rubber sleeve fitted onto the central tube. By inserting a fracturing ball into the central flow channel formed by the upper connector, nozzle, sealing mechanism, and central tube and applying pressure, the sealing mechanism can be driven to compress the elastic element and move. This invention features a compact structure, enables multi-stage fracturing in a single well setup, and achieves higher construction efficiency.

Description

Technical Field

[0001] This utility model belongs to the technical field of downhole tools for oil and gas fields, and specifically relates to an integrated fracturing and sealing tool assembly. Background Technology

[0002] With the deepening of oil and gas resource development, horizontal well fracturing technology has become a key means of exploiting unconventional oil and gas resources such as low-permeability reservoirs, tight sandstone, and shale gas. Currently, the commonly used field fracturing technologies, namely stationary tubing sliding sleeve staged fracturing and dragged tubing fracturing, both have significant limitations. The former is limited by the tool class, making it difficult to meet the needs of multi-stage fracturing, and the tubing string is difficult to retrieve after fracturing; the latter, although simple in structure, requires frequent dragging of the tubing string to change layers, resulting in low construction efficiency, and repeated dragging can easily damage the seals, leading to long operation cycles and high costs.

[0003] Therefore, there is an urgent need in this field for a downhole tool that can achieve efficient, multi-stage fracturing and reduce the number of times the tubing string can be dragged. Utility Model Content

[0004] This utility model addresses the aforementioned problems and overcomes the shortcomings of existing technologies by providing an integrated fracturing and sealing tool assembly. This utility model has a compact structure, enables multi-stage fracturing to be completed in a single well run, and has higher construction efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] This utility model provides an integrated fracturing and packing tool assembly, characterized in that it includes an upper fracturing control unit, a sliding sleeve reset unit, and a packer unit connected sequentially from top to bottom; the upper fracturing control unit includes an upper connector, a sandblasting sliding sleeve, and a nozzle, wherein the upper connector is connected to the upper end of the sandblasting sliding sleeve, and the nozzle is housed in the inner cavity of the sandblasting sliding sleeve; both the sandblasting sliding sleeve and the nozzle are provided with corresponding side holes, and a controllable movable sealing mechanism is provided for opening and closing the fracturing channel formed by the side holes; the sliding sleeve reset unit includes a cylinder and an elastic element disposed therein; the packer unit includes a central tube and a rubber sleeve sleeved on the central tube; by inserting a fracturing ball into the central flow channel formed by the upper connector, the nozzle, the sealing mechanism, and the central tube and applying pressure, the sealing mechanism can be driven to compress the elastic element and move, thereby opening the fracturing channel, while the pressurized liquid drives the rubber sleeve to expand and seal.

[0007] Furthermore, the sealing mechanism includes a sealing sleeve, a first connecting sleeve, and a second connecting sleeve; the upper inner side of the second connecting sleeve is provided with a ball seat for setting the fracturing ball, and the lower end of the second connecting sleeve is connected to the elastic element; the sealing sleeve is connected to the second connecting sleeve through the first connecting sleeve.

[0008] Furthermore, the minimum inner diameter of the flow channel below the ball seat is not less than 30mm.

[0009] Furthermore, the outer side of the sealing sleeve is sealed to the inner side of the nozzle by a rubber sleeve and a first combined seal, and is axially positioned by a positioning structure consisting of a first positioning cap, a second positioning cap, and a retaining ring.

[0010] Furthermore, the sliding sleeve reset unit is connected to the packer unit via a third connecting sleeve; a second combined seal is installed in the inner annular groove of the third connecting sleeve to form a seal with the lower end of the second connecting sleeve; the elastic element of the sliding sleeve reset unit includes a spring, and a first spring washer and a second spring washer are respectively provided at both ends of the spring and housed in the cylinder; the inner side of the upper end of the third connecting sleeve is locked by a nut.

[0011] Furthermore, the end boss of the upper connector is inserted into the end groove of the nozzle; the nozzle and the inner cavity of the sandblasting sleeve are sealed by an O-ring and a washer.

[0012] Furthermore, the packer unit also includes an upper pressure ring sleeved on the upper part of the rubber tube and a lower pressure ring sleeved on the lower part of the rubber tube; the lower end of the rubber tube is threadedly connected to a floating piston, and the floating piston is threadedly connected to a centering cap; the lower end of the central tube is threadedly connected to a lower connector, and the lower connector is threadedly connected to a guide cap.

[0013] Furthermore, the preload of the elastic element is set to prevent the sealing mechanism from moving and opening when the construction discharge rate does not exceed 9 m³ / min and the fracturing ball is not put in.

[0014] Furthermore, the nozzle is made of a material with a hardness of not less than 60 HRC, and the inner surfaces of the parts that come into contact with the sand-carrying liquid are all treated with wear-resistant materials.

[0015] The beneficial effects of this utility model.

[0016] This invention adopts an integrated design of packer and fracturing sleeve, resulting in a compact structure. By connecting multiple tool assemblies in series within the tubing string and using fracturing balls of different sizes, it enables multiple fracturing stages to be completed with a single well run and each time the tubing string is moved without moving. This significantly reduces the number of tubing string moves, improves construction efficiency, shortens the cycle time, and reduces costs.

[0017] By precisely setting the inner diameter difference of each tool and the preload of the spring, it is ensured that the slide sleeve of that stage will only open when a fracturing ball of the corresponding size is inserted under the construction displacement, and the slide sleeve without inserted ball remains closed, thus achieving precise and reliable segmented fracturing control.

[0018] The nozzle is made of high-hardness (≥60HRC) wear-resistant material, and the other inner surfaces of the flow passage are also treated with wear resistance, enabling the tool to withstand the scouring of large-volume sand-carrying liquid, with a long service life, and meeting the harsh on-site construction requirements. Attached Figure Description

[0019] To make the technical problems solved, the technical solutions, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0020] Figure 1 This is a schematic diagram of the overall half-sectional structure of this utility model.

[0021] Figure 2 This is a utility model Figure 1 A schematic diagram of the upper structure.

[0022] Figure 3 This is a utility model Figure 1 A schematic diagram of the central structure.

[0023] Figure 4 This is a utility model Figure 1 A schematic diagram of the lower structure.

[0024] The markings in the diagram are as follows: 1 is the upper connector, 2 is the sealing sleeve, 3 is the rubber sleeve, 4 is the first positioning cap, 5 is the retaining ring, 6 is the second positioning cap, 7 is the nozzle, 8 is the first combined seal, 9 is the sandblasting sliding sleeve, 10 is the first connecting sleeve, 11 is the cylinder, 12 is the second connecting sleeve, 13 is the ball seat, 14 is the first spring washer, 15 is the second spring washer, 16 is the spring, 17 is the nut, 18 is the third connecting sleeve, 19 is the second combined seal, 20 is the upper pressure ring, 21 is the central tube, 22 is the rubber sleeve, 23 is the lower pressure ring, 24 is the floating piston, 25 is the centering cap, 26 is the guide cap, 27 is the lower connector, 28 is the washer, 29 is the O-ring, and 30 is the fracturing ball. Detailed Implementation

[0025] As shown in the accompanying drawings, this embodiment provides an integrated fracturing and packing tool assembly, which consists of three main functional units from top to bottom: an upper fracturing control unit, a sliding sleeve reset unit, and a packer unit, connected sequentially from top to bottom.

[0026] The upper fracturing control unit constitutes the upper structure and core of the fracturing flow channel control of this tool. This unit includes an upper connector 1, a sandblasting sleeve 9, and a nozzle 7. The upper connector 1 is connected to the upper end of the sandblasting sleeve 9, serving as the connection interface with the upper-stage tubing; the nozzle 7 is housed within the inner cavity of the sandblasting sleeve 9. The end boss of the upper connector 1 engages with the end groove of the nozzle 7 to prevent relative rotation. Both the sandblasting sleeve 9 and the nozzle 7 have corresponding side holes on their cylindrical walls. An O-ring 29 and a washer 28 are used to seal the nozzle 7 to the inner cavity of the sandblasting sleeve 9.

[0027] A controllable movable sealing mechanism is disposed within this unit to seal the fracturing channel formed by the side hole in the initial state. This sealing mechanism includes a sealing sleeve 2, a first connecting sleeve 10, and a second connecting sleeve 12. The upper inner side of the second connecting sleeve 12 is provided with a ball seat 13 for setting the fracturing ball 30, and the minimum inner diameter of the flow channel below the ball seat 13 is not less than 30 mm. The lower end of the second connecting sleeve 12 is connected to the elastic element of the sliding sleeve reset unit. The sealing sleeve 2 is connected to the second connecting sleeve 12 via the first connecting sleeve 10, thereby achieving linkage. The outer side of the sealing sleeve 2 is provided with a rubber sleeve 3 and a first combined seal 8 for forming a tight seal with the inner side of the nozzle 7; the sealing sleeve 2 is precisely axially positioned by a positioning structure composed of a first positioning cap 4, a second positioning cap 6, and a retaining ring 5.

[0028] The sliding sleeve reset unit is located below the upper fracturing control unit and includes a cylinder 11 and an elastic element disposed inside the cylinder 11. Specifically, the elastic element is a spring 16, with a first spring washer 14 and a second spring washer 15 at each end, and the spring 16 is entirely housed inside the cylinder 11. The preload of the spring 16 is precisely set to prevent the sealing mechanism from moving and opening when the fracturing displacement does not exceed 9 m³ / min and the fracturing ball 30 is not deployed.

[0029] The sliding sleeve reset unit and the packer unit are connected via a third connecting sleeve 18. A second combined seal 19 is installed in the inner annular groove of the third connecting sleeve 18. This seal is used to contact the lower end of the second connecting sleeve 12 and form a dynamic seal. The upper inner side of the third connecting sleeve 18 is locked with a nut 17 to fix the initial position of the internal components.

[0030] The packer unit constitutes the lower part of the tool, including a central tube 21 and a rubber sleeve 22 fitted onto the central tube 21. The upper end of the central tube 21 is threadedly connected to the lower end of a third connecting sleeve 18. The unit also includes an upper pressure ring 20 fitted onto the upper part of the rubber sleeve 22 and a lower pressure ring 23 fitted onto the lower part of the rubber sleeve 22. The lower end of the rubber sleeve 22 is threadedly connected to a floating piston 24, which is further threadedly connected to a centralizing cap 25. The lower end of the central tube 21 is threadedly connected to a lower connector 27, the end of which is connected to a guide cap 26 to facilitate the smooth lowering of the tool string into the well.

[0031] The working principle of this tool assembly is as follows:

[0032] A key innovation of this tool assembly lies in its design, which allows multiple assemblies to be connected in series on a single tubing string to form a highly efficient multi-stage fracturing system. Specifically, taking a seven-stage design as an example, each tool assembly's second connecting sleeve 12, ball seat 13, spring 16, nut 17, third connecting sleeve 18, second combined seal 19, and fracturing ball 30 serve as stage components. According to the increasing stage number, the dimensions of each tool assembly's stage components are set from smallest to largest (smallest at the bottom for stage one, largest at the top for stage seven). A series of fracturing balls 30 with increasing diameters are used to ensure that the fracturing balls 30 are inserted into the tool assembly cavity from smallest to largest size according to the corresponding stage, and seal with the corresponding ball seat 13. Simultaneously, the starting pressure of the nozzle 7 flow channel meets the operational requirements.

[0033] During operation, the smallest diameter fracturing ball 30 is first deployed, which will set on the smallest diameter ball seat 13 of the lowest-level tool. After pressurization in the tubing, the pressure pushes the ball seat 13 and the second connecting sleeve 12 to compress the spring 16 downwards, causing the sealing sleeve 2 to leave the sealing position, thereby opening the fracturing channel of this stage of the tool. At the same time, the pressurized fluid drives the rubber sleeve 22 to expand and seal, isolating the formation and completing the first stage of fracturing.

[0034] Then, the smallest diameter fracturing ball 30 is inserted. It will pass through all the lower-level tools, set on the ball seat 13 of the penultimate-level tool, and open that level of tool. This process is repeated to achieve bottom-up fracturing.

[0035] After one round of fracturing is completed, the tubing is depressurized. Under the restoring force of spring 16, the second connecting sleeve 12, the first connecting sleeve 10, and the sealing sleeve 2 move upward and reset, closing the fracturing channel; the rubber sleeve 22 releases itself through its own elastic contraction. After all the fracturing balls 30 in the well are returned to the surface through reverse circulation well washing, the entire tubing string can be dragged to the next target section, and the above ball-dropping fracturing process can be repeated to achieve a new round of multi-stage fracturing, thereby significantly improving the efficiency of staged fracturing construction.

[0036] It is understood that the above specific description of this utility model is only used to illustrate this utility model and is not limited to the technical solutions described in the embodiments of this utility model. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to this utility model to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of this utility model.

Claims

1. A frac-and-pack integrated tool assembly, comprising: The system includes an upper fracturing control unit, a sliding sleeve reset unit, and a packer unit connected sequentially from top to bottom. The upper fracturing control unit includes an upper connector (1), a sandblasting sliding sleeve (9), and a nozzle (7), wherein the upper connector (1) is connected to the upper end of the sandblasting sliding sleeve (9), and the nozzle (7) is housed in the inner cavity of the sandblasting sliding sleeve (9). Both the sandblasting sliding sleeve (9) and the nozzle (7) are provided with corresponding side holes and a controllable sealing mechanism for opening and closing the fracturing channel formed by the side holes. The sliding sleeve reset unit includes a cylinder (11) and an elastic element disposed therein; the packer unit includes a central tube (21) and a rubber sleeve (22) sleeved on the central tube (21); by injecting a fracturing ball (30) into the central flow channel formed by the upper connector (1), the nozzle (7), the sealing mechanism and the central tube (21) and applying pressure, the sealing mechanism can be driven to compress the elastic element and move, thereby opening the fracturing channel, while the pressurized liquid drives the rubber sleeve (22) to expand and seal.

2. The fracturing packoff integrated tool assembly of claim 1, wherein, The sealing mechanism includes a sealing sleeve (2), a first connecting sleeve (10), and a second connecting sleeve (12); the upper inner side of the second connecting sleeve (12) is provided with a ball seat (13) for setting the fracturing ball (30), and the lower end of the second connecting sleeve (12) is connected to the elastic element; the sealing sleeve (2) is connected to the second connecting sleeve (12) through the first connecting sleeve (10).

3. The fracturing packoff integration tool assembly of claim 2, wherein, The minimum inner diameter of the flow channel below the ball seat (13) is not less than 30 mm.

4. The fracturing packoff integration tool assembly of claim 2, wherein, The outer side of the sealing sleeve (2) is sealed to the inner side of the nozzle (7) by the rubber sleeve (3) and the first combined seal (8), and is axially positioned by the positioning structure composed of the first positioning cap (4), the second positioning cap (6) and the retaining ring (5).

5. The fracturing packoff integration tool assembly of claim 2, wherein, The sliding sleeve reset unit is connected to the packer unit through a third connecting sleeve (18); a second combined seal (19) is installed in the inner annular groove of the third connecting sleeve (18) for forming a seal with the lower end of the second connecting sleeve (12); the elastic element of the sliding sleeve reset unit includes a spring (16), and a first spring pad (14) and a second spring pad (15) are respectively provided at both ends of the spring (16) and are housed in the cylinder (11); the inner side of the upper end of the third connecting sleeve (18) is locked by a nut (17).

6. The fracturing packoff integration tool assembly of claim 1, wherein, The end boss of the upper connector (1) is inserted into the end groove of the nozzle (7); the nozzle (7) and the inner cavity of the sandblasting sleeve (9) are sealed by an O-ring (29) and a washer (28).

7. The fracturing packoff integration tool assembly of claim 1, wherein, The packer unit further includes an upper pressure ring (20) sleeved on the upper part of the rubber tube (22) and a lower pressure ring (23) sleeved on the lower part of the rubber tube (22); the lower end of the rubber tube (22) is threadedly connected to the floating piston (24), and the floating piston (24) is threadedly connected to the centering cap (25); the lower end of the central tube (21) is threadedly connected to the lower connector (27), and the lower connector (27) is threadedly connected to the guide cap (26).

8. The fracturing packoff integration tool assembly of claim 7, wherein, The pre-tightening force of the elastic element is set to prevent the sealing mechanism from moving open when the construction flow rate is not more than 9 m3 / min and the fracturing ball (30) is not put in.

9. The fracturing packoff integration tool assembly of claim 7, wherein, The material hardness of the nozzle (7) is not less than 60HRC, and the inner surface of the part in contact with the sand-carrying liquid is wear-resistant treated.

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