Perforation-free fracturing well cementation float collar

Abstract

The invention relates to the technical field of downhole tools, in particular to a perforation-free fracturing well cementation float collar to solve the problem that a conventional fracturing tool is low in well completion success rate. The float collar is in a first state and a second state. In the first state, liquid flows into the first liquid injection channel from the upper part of the body and flows out from the lower part of the body; when the first state is switched to the second state, the rubber plug is put into the body, the rubber plug is clamped with the movable valve element, and the overflowing hole of the rubber plug is in butt joint with the liquid discharging hole; the liquid discharge hole is communicated with the outside to form a second liquid injection channel; and in the second state, the liquid flows in from the upper part of the body and is divided into the first liquid injection channel and the second liquid injection channel. In the fracturing operation process, a cement layer of an original fracturing operation section is replaced with displacing liquid, pressure can be conveniently transmitted to the stratum, the success rate of fracturing operation can be effectively increased, meanwhile, the lower portion discharges liquid through multiple channels, and the pressure of a well opening can be effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of downhole tool technology, and in particular to a perforation-free cementing float. Background Technology

[0002] After cementing is completed, downhole fracturing is required. Downhole fracturing involves injecting high-pressure fluid into the oil and gas reservoir to create pressure at the bottom of the well that exceeds the rock fracture pressure, causing fractures in the reservoir rock and providing new flow channels for oil and gas. This increases the permeability of oil and gas from the reservoir to the wellbore, thereby achieving the goal of increasing production.

[0003] Horizontal well fracturing operations often employ a pump-pumped bridge plug staged fracturing process. In casing-completed horizontal wells, the fracturing process mainly involves: the first stage uses coiled tubing for perforation and casing fracturing; the remaining stages use cable-pumped bridge plugs for clustered perforation and staged fracturing; and finally, after all fracturing is completed, the bridge plugs are drilled and ground for production. However, during coiled tubing operations, due to factors such as complex wellbore trajectories, large well inclination angles and doglegs, and the "upturned" shape at the end of the horizontal section, problems such as stuck pipe, self-locking, and falling debris are prone to occur. Furthermore, coiled tubing is prone to buckling and deformation, increasing the difficulty of operations. From coiled tubing installation and perforation gun insertion to coiled tubing equipment removal, it takes at least 5-8 days. If coiled tubing self-locking occurs, a large amount of expensive metal drag-reducing agent must be injected, significantly increasing costs and potentially damaging the reservoir.

[0004] Among them, the first-stage cemented well fracturing toe sleeve tool is the first-stage fracturing sleeve. It is inserted into the well along with the casing to the predetermined position. Its perimeter needs to be filled with cement for solidification. This device is not only expensive, but also has a low success rate in on-site construction. Therefore, a tool is needed to replace the toe sleeve. Summary of the Invention

[0005] To alleviate the above-mentioned technical problems, the technical solution provided by the present invention is as follows: This invention provides a perforation-free fracturing cementing float, comprising a first state and a second state; In the first state, the liquid flows into the first injection channel from the upper part of the body and flows out from the lower part of the body; When switching from the first state to the second state, a rubber stopper is inserted into the body to make the rubber stopper engage with the movable valve core, closing the first liquid injection channel. The movable valve core is then pressed down to make it connect with the drain hole of the body. The movable valve core is then pressed down again to make it continue to move down, so that the flow hole of the rubber stopper aligns with the drain hole. The drain hole connects to the outside to form a second injection channel; In the second state, the liquid flows in from the top of the body and is diverted into the first injection channel and the second injection channel.

[0006] Furthermore, A valve core sleeve is installed inside the body; The movable valve core is threadedly connected to the upper part of the valve core sleeve; The valve core sleeve is slidably connected to the body; A valve stem is inserted into the valve core sleeve; There are gaps between the movable valve core and the valve stem, and between the valve core sleeve and the valve stem; The movable valve core and valve stem are connected to form the first injection channel.

[0007] Furthermore, A spring is installed between the valve stem and the valve core sleeve.

[0008] Furthermore, A fixed valve core is provided at the upper part of the valve core sleeve; The outer wall of the fixed valve core is threadedly connected to the body. The movable valve core is inserted into the fixed valve core and fixedly connected by the first shear pin.

[0009] Furthermore, The rubber stopper consists of a body, an inner sleeve, and an outer sleeve; The inner sleeve is slidably connected to the main body and is fixedly connected by a second shear pin; The outer cover is snapped onto the outer wall of the main body.

[0010] Furthermore, After the rubber stopper is inserted into the body, the lower part of the rubber stopper abuts against the movable valve core. After the first pressure is applied and the first shear pin breaks, the rubber stopper moves downward with the movable valve core. After the outer wall of the rubber stopper comes into contact with the fixed valve core, the rubber stopper stops moving, allowing the circulation hole on the movable valve core to connect with the drain hole.

[0011] Furthermore, After the second pressurization, the second shear pin breaks, and the inner sleeve pushes the movable valve core downward, so that the flow hole is aligned with the drain hole, and the flow hole is connected to the drain hole and the circulation hole respectively.

[0012] Furthermore, The flow passage is an elongated orifice, and its size is larger than that of the drain orifice.

[0013] Furthermore, The first shear nail broke after being subjected to a shear force of 30 MPa.

[0014] Furthermore, The second shear nail broke after being subjected to a shear force of 35 MPa.

[0015] The beneficial effects of the perforation-free fracturing cementing float in this invention are analyzed as follows: This invention provides a perforation-free cementing float collar, comprising a first state and a second state. In the first state, liquid flows from the upper part of the body into a first injection channel and flows out from the lower part of the body. When switching from the first state to the second state, a rubber plug is inserted into the body, causing the rubber plug to engage with a movable valve core, closing the first injection channel. After pressurization, the movable valve core moves downward, connecting with the drain hole of the body. Pressurization is applied again to make the movable valve core continue to move downward, connecting the flow hole of the rubber plug with the drain hole. The drain hole connects with the outside to form a second injection channel. In the second state, liquid flows from the upper part of the body and is diverted into the first and second injection channels.

[0016] In its first state, this device functions as a check valve and packer, preventing fluid backflow at the bottom of the well and facilitating cementing operations. After cementing, inserting a rubber plug enables the device to perform fracturing operations. During fracturing, displacement fluid replaces the cement layer in the original fracturing section, facilitating pressure transmission to the formation and effectively improving the success rate of fracturing operations. Simultaneously, multi-channel drainage at the bottom effectively reduces the pressure at the wellhead. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of the perforation-free fracturing cementing float in the first state provided for an embodiment of the present invention; Figure 2 This is a schematic diagram of the rubber stopper structure; Figure 3 A schematic diagram of the structure of the perforation-free fracturing cementing float after the rubber plug is inserted; Figure 4 A schematic diagram of the structure of the non-perforated fracturing cementing float ring after the first shear pin breaks; Figure 5 A schematic diagram of the structure of the perforation-free fracturing cementing float ring provided in the second state according to an embodiment of the present invention.

[0019] icon: 100-body; 110-drain hole; 200 - Rubber plug; 210 - Flow hole; 220 - Main body; 230 - Inner sleeve; 240 - Outer sleeve; 250 - Second shear pin; 300 - Movable valve core; 310 - First shear pin; 320 - Circulation hole; 400-valve core sleeve; 500 - Valve stem; 600-Spring; 700 - Fixed valve core. Detailed Implementation

[0020] Because existing toe-end sliding sleeve tools are used as the first-stage fracturing sliding sleeves, they are costly and have a low success rate, making it difficult to meet routine needs.

[0021] In view of this, such as Figures 1 to 5 As shown, this solution provides a perforation-free fracturing cementing float to alleviate the above-mentioned problems.

[0022] This device includes a first state and a second state; In the first state, liquid flows from the upper part of the body 100 into the first injection channel and flows out from the lower part of the body 100; When switching from the first state to the second state, a rubber stopper 200 is inserted into the body 100, so that the rubber stopper 200 engages with the movable valve core 300, closing the first liquid injection channel. The movable valve core 300 is then pressed down to connect with the drain hole 110 of the body 100. The movable valve core 300 is then pressed down again to continue moving down, so that the flow hole 210 of the rubber stopper 200 aligns with the drain hole 110. The drain hole 110 is connected to the outside to form a second injection channel; In the second state, liquid flows in from the upper part of the body 100 and is diverted into the first injection channel and the second injection channel.

[0023] Specifically, this device is connected to the lower part of the casing string. During cementing operations, pre-flush fluid, cement slurry, and displacement drilling fluid are injected sequentially. During this process, liquid flows from the casing string into the main body 100 and flows out from the lower part of the main body 100 along the first injection channel, allowing the cement slurry and displacement drilling fluid to enter the annular space between the casing and the wellbore. After confirming that the annular space is filled with cement slurry and displacement drilling fluid, a rubber stopper 200 is inserted into the casing string, and the rubber stopper 200 is pushed open by a pressure of less than 25 MPa. The rubber plug 200 is inserted into the body 100, causing it to abut against the movable valve core 300, and the retaining spring at the bottom of the rubber plug 200 is tightened to prevent the rubber plug 200 from reversing due to changes in bottom hole pressure. When preparing to carry out fracturing operations after the cement slurry has solidified after the curing period, the pressure is gradually increased from the wellhead, eventually causing the movable valve core 300 to move down to the predetermined position, so that the first injection channel and the second injection channel are respectively connected to the casing string, thereby allowing the liquid entering the body 100 from the casing string to flow out along the first injection channel or the second injection channel.

[0024] In this design, a valve core sleeve 400 is installed inside the main body 100; The movable valve core 300 is threadedly connected to the upper part of the valve core sleeve 400; The valve core sleeve 400 is slidably connected to the body 100; A valve stem 500 is inserted into the valve core sleeve 400. There are gaps between the movable valve core 300 and the valve stem 500, and between the valve core sleeve 400 and the valve stem 500; The movable valve core 300 is connected to the valve stem 500 to form the first injection channel; A spring 600 is provided between the valve stem 500 and the valve core sleeve 400; A fixed valve core 700 is provided on the upper part of the valve core sleeve 400; The outer wall of the fixed valve core 700 is threaded to the body 100. The movable valve core 300 is inserted into the fixed valve core 700 and fixedly connected by the first shear pin 310.

[0025] Specifically, the top of the valve stem 500 is umbrella-shaped, and the lower part of the movable valve core 300 has an inclined surface that matches the umbrella surface of the valve stem 500. There is always a certain gap between the umbrella surface and the inclined surface. The lower part of the valve stem 500 is inserted into the valve core sleeve 400, and there is a gap between the two for liquid to pass through. The spring 600 is a compression spring that always has the ability to drive the valve stem 500 to move upward. When the amount of liquid entering the movable valve core 300 is large, the spring 600 is compressed and contracts, which increases the gap between the movable valve core 300 and the valve stem 500. When the amount of liquid is small, the spring 600 returns to its original position, which resets the gap between the movable valve core 300 and the valve stem 500.

[0026] In this design, the rubber stopper 200 includes a main body 220, an inner sleeve 230, and an outer sleeve 240; The inner sleeve 230 is slidably connected to the main body 220 and is fixedly connected by the second shear pin 250; The outer casing 240 is snapped into the outer wall of the main body 220; After the rubber stopper 200 is inserted into the body 100, the lower part of the rubber stopper 200 abuts against the movable valve core 300. After the first pressure is applied and the first shearing nail 310 breaks, the rubber stopper 200 moves downward with the movable valve core 300. After the outer wall of the rubber stopper 200 comes into contact with the fixed valve core 700, the rubber stopper 200 stops moving, so that the circulation hole 320 on the movable valve core 300 is connected to the drain hole 110. After the second pressurization, the second shear nail 250 breaks, and the inner sleeve 230 pushes the movable valve core 300 to move downward, so that the flow hole 210 is aligned with the drain hole 110, and the flow hole 210 is connected to the drain hole 110 and the circulation hole 320 respectively. The first shearing nail 310 broke after being subjected to a shearing force of 30 MPa; The second shearing nail 250 broke after being subjected to a shearing force of 35 MPa.

[0027] Specifically, the bottom of the inner sleeve 230 is a closed structure. After the first shear pin 310 breaks for the first time, the rubber stopper 200 and the movable valve core 300 move down synchronously. When the protrusion of the main body 220 engages with the fixed valve core 700, the movement stops. At this time, the circulation hole 320 is directly opposite the drain hole 110. At the same time, after pressurization again, the second shear pin 250 breaks, causing the inner sleeve 230 and the movable valve core 300 to move down synchronously. After moving down to the predetermined position, the flow hole 210 is opposite to the drain hole 110. 210 is an elongated hole, and its size is larger than that of the drain hole 110, so that the injected liquid can fully enter the cavity formed by the body 100, the inner sleeve 230 and the movable valve core 300, thereby causing the liquid to be diverted. Part of it is discharged to the outside through the drain hole 110, and the other part flows into the movable valve core 300 through the circulation hole 320, and flows downward through the gap between the valve stem 500 and the valve core sleeve 400. The increased liquid flow rate is increased by increasing the drain outlet, thereby reducing the wellhead pressure and facilitating subsequent fracturing operations.

[0028] This solution has at least the following beneficial effects: When using conventional toe-end sliding sleeves, there is cement filling between them and the formation. During fracturing operations, the cement needs to be expanded and fractured before fracturing the formation, resulting in poor pressure efficiency and low success rate. This solution provides a perforation-free fracturing cementing float collar to replace the toe-end sliding sleeve in fracturing operations. During cementing operations, the fluid flows from top to bottom, and this tool can prevent fluid backflow at the bottom of the well. During fracturing operations, by displacing the drilling fluid and lifting the cement slurry at the bottom, the section to be fractured is free from the interference of solidified cement. The expansion of the fluid then fractures the formation, effectively reducing wellhead pressure and significantly improving the success rate of the operation.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A perforation-free fracturing cementing float ring, characterized in that: Includes the first state and the second state; In the first state, liquid flows from the upper part of the body (100) into the first injection channel and flows out from the lower part of the body (100); When switching from the first state to the second state, a rubber stopper (200) is inserted into the body (100) to make the rubber stopper (200) engage with the movable valve core (300), closing the first injection channel. The movable valve core (300) is then pressed down to make it connect with the drain hole (110) of the body (100). The movable valve core (300) is then pressed down again to make it continue to move down, so that the flow hole (210) of the rubber stopper (200) connects with the drain hole (110). The drain hole (110) is connected to the outside to form a second injection channel; In the second state, the liquid flows in from the upper part of the body (100) and is diverted into the first injection channel and the second injection channel; A valve core sleeve (400) is provided inside the body (100). The movable valve core (300) is threadedly connected to the upper part of the valve core sleeve (400); The valve core sleeve (400) is slidably connected to the body (100); A valve stem (500) is inserted into the valve core sleeve (400). There are gaps between the movable valve core (300) and the valve stem (500), and between the valve core sleeve (400) and the valve stem (500); The movable valve core (300) and the valve stem (500) are connected to form a first injection channel; A fixed valve core (700) is provided on the upper part of the valve core sleeve (400). The outer wall of the fixed valve core (700) is threadedly connected to the body (100); The movable valve core (300) is inserted into the fixed valve core (700) and fixedly connected by the first shear pin (310).

2. The perforation-free fracturing cementing float collar according to claim 1, characterized in that: A spring (600) is provided between the valve stem (500) and the valve core sleeve (400).

3. The perforation-free fracturing cementing float collar according to claim 2, characterized in that: The rubber stopper (200) includes a body (220), an inner sleeve (230), and an outer sleeve (240); The inner sleeve (230) is slidably connected to the main body (220) and fixedly connected by the second shear pin (250); The outer jacket (240) is snapped onto the outer wall of the main body (220).

4. The perforation-free fracturing cementing float collar according to claim 3, characterized in that: After the rubber plug (200) is inserted into the body (100), the lower part of the rubber plug (200) abuts against the movable valve core (300). After the first pressure is applied and the first shearing nail (310) breaks, the rubber plug (200) moves downward with the movable valve core (300). After the outer wall of the rubber stopper (200) comes into contact with the fixed valve core (700), the rubber stopper (200) stops moving, so that the circulation hole (320) on the movable valve core (300) is connected to the drain hole (110).

5. The perforation-free fracturing cementing float collar according to claim 4, characterized in that: After the second pressurization, the second shear pin (250) breaks, and the inner sleeve (230) pushes the movable valve core (300) to move downward, so that the flow hole (210) is directly opposite the drain hole (110), so that the flow hole (210) is connected to the drain hole (110) and the circulation hole (320) respectively.

6. The perforation-free fracturing cementing float collar according to claim 5, characterized in that: The flow passage (210) is an elongated hole and its size is larger than that of the drain hole (110).

7. The perforation-free fracturing cementing float according to claim 6, characterized in that: The first shearing nail (310) breaks after being subjected to a shearing force of 30 MPa.

8. The perforation-free fracturing cementing float according to claim 7, characterized in that: The second shearing nail (250) broke after being subjected to a shearing force of 35 MPa.

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