A small-diameter oil pipe dusting cylinder and a dusting method

Abstract

The application discloses a small-diameter oil pipe dusting cylinder and a dusting method, and belongs to the technical field of oil pipe dusting and plugging under pressure in oil and gas fields; the existing dusting cylinder is not suitable for being used for cementing in small-diameter oil pipes; the dusting cylinder comprises a piston assembly, an upper sleeve, a lower sleeve and a striking assembly; the upper sleeve is connected with the lower sleeve, and the inner cavities of the upper sleeve and the lower sleeve are communicated; the piston assembly is arranged in the upper sleeve; the striking assembly is arranged in the lower sleeve; a valve is arranged on one end of a striking rod close to the upper sleeve, the valve is used for plugging the port of the lower sleeve; the piston assembly is used for pushing the cement slurry in the upper sleeve to the lower sleeve; the cement slurry is introduced into the lower sleeve from the upper sleeve through the port, and is discharged from the cement slurry outlet on the side of the lower sleeve; the dusting cylinder is provided with the piston in the upper sleeve, the cement slurry is pushed out of the upper sleeve through the extrusion of the piston, and the problem that the cement slurry cannot be naturally discharged due to strong adhesion is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of ash-filling and sealing technology for oil pipes during pressurized operations in oil and gas fields, and particularly to an ash-filling cylinder and ash-filling method for small-diameter oil pipes. Background Technology

[0002] In pressurized operations at oil and gas wells, simply using a plugging device to seal the tubing cannot guarantee a good seal or ensure operational safety. A poorly sealed plug can lead to gas leaks and even ejection, causing serious safety accidents. A safer approach involves filling the top of the plugging device inside the tubing with sand and gravel, then pouring cement slurry onto the sand and gravel surface to solidify into a cement plug. This creates a double-layer sealing barrier within the tubing, significantly improving the sealing effect. A key technology in forming the cement plug is the transportation and release of the cement slurry. Current technology uses a slurry pump to pour cement into the tubing. When using the slurry pump, a certain amount of cement slurry is first loaded into the pump, then delivered to the predetermined injection depth via cable or wire rope. The pump is then opened by electric blasting or mechanical impact, allowing the cement slurry to flow out and solidify within the wellbore, forming a seal.

[0003] Current cement plugging systems are suitable for sealing large-diameter tubing or casing, but their effectiveness is poor for tubing sizes of 2-7 / 8" and smaller. This is because the inner diameter of the cement plugging system for small-diameter tubing is very small, typically below φ40mm, while the viscosity and surface tension of cement slurry are high. Therefore, it is difficult for the cement slurry to flow out completely naturally under its own weight inside the cement plugging system for small-diameter tubing. Furthermore, in actual construction, the cement plug is often only less than 10cm high. If the cement column is not continuously bonded, stability and sealing cannot be guaranteed. Therefore, cement plugging inside small-diameter tubing is a current thorny problem in the industry, and this issue exists in the live tubing plugging technology used by various oil and gas fields in China, including Changqing Oilfield and Daqing Oilfield, as well as various live-line service companies. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a ash-discharging cylinder and ash-discharging method for small-diameter oil pipes, thereby solving the problem that existing ash-discharging cylinders are not suitable for inserting cement plugs into small-diameter oil pipes.

[0005] Firstly, in order to achieve the aforementioned objectives, the technical solution adopted by this invention is as follows:

[0006] A small-diameter oil pipe ash discharge cylinder includes a piston assembly, an upper sleeve, a lower sleeve, and an impact assembly; the upper sleeve and the lower sleeve are connected, and the inner cavities of the upper sleeve and the lower sleeve are in communication; the piston assembly is provided inside the upper sleeve; the impact assembly is provided inside the lower sleeve, and a valve is provided at one end of the impact assembly near the upper sleeve, the valve sealing the port of the lower sleeve.

[0007] In this design, a piston assembly is designed inside the upper sleeve. During ash pouring, the piston assembly moves inside the upper sleeve, pushing out all the cement slurry inside, thus avoiding the problem of cement slurry sticking inside the small-diameter oil pipe. An impact assembly is installed inside the lower sleeve. As the ash pouring cylinder moves downward, the impact assembly impacts the sand and gravel surface, and the valve moves upward to open the port of the lower sleeve. The cement slurry pushed out of the upper sleeve can then flow through the port into the lower sleeve and out through the slurry outlet on its side, thus releasing the cement slurry. This release process is entirely achieved through the mechanical structure of the impact assembly, which is highly controllable and safe in actual operation.

[0008] Furthermore, the piston assembly includes a piston connecting rod, one end of which is provided with a piston, and the other end of which is provided with a connector; the end of the piston connecting rod with the piston is located inside the upper sleeve.

[0009] In this design, a piston is incorporated to facilitate the complete expulsion of cement slurry from the upper sleeve, thus preventing any cement slurry residue from remaining in the upper sleeve.

[0010] Furthermore, the upper sleeve includes a sleeve body and a sleeve cap, the sleeve body and the sleeve cap are connected, and the piston is disposed inside the sleeve body.

[0011] In this solution, when it is necessary to fill the upper sleeve with cement grout, open the sleeve cap, fill in the cement grout, then put in the piston and cover the sleeve cap, so as to facilitate the filling of cement grout during operation.

[0012] Furthermore, the piston is equipped with a limiting snap ring, and a limiting ring groove is opened at the bottom of the upper sleeve; when the piston moves to the bottom of the upper sleeve, the limiting snap ring is embedded in the limiting ring groove to fix the piston.

[0013] In this design, a limiting snap ring is embedded in the limiting ring groove to fix the piston and the upper sleeve as a whole. When the ash discharge cylinder is pulled out from the oil pipe after the ash discharge is completed, the whole unit can be quickly pulled out. Furthermore, the limiting snap ring embedded in the limiting ring groove can also ensure that cement slurry will not be sucked back into the chamber during the process of lifting the ash discharge cylinder.

[0014] Furthermore, the piston assembly is fixed to the upper sleeve by piston shear pins; the impact assembly is fixed to the lower sleeve by impact shear pins.

[0015] In this solution, the piston and impact rod are fixed by piston shear pin and impact shear pin respectively. In the actual ash dumping operation, the ash dumping cylinder is placed into the oil pipe and impacted downwards to release the fixing of the impact rod and piston, thereby releasing the cement slurry. Compared with the existing explosion method for releasing cement slurry, this method is more controllable and safer.

[0016] Furthermore, the piston shear pin is made of copper; the impact shear pin is made of aluminum.

[0017] In this design, the piston shear pin and the impact shear pin are made of copper and aluminum, respectively. During the impact, the aluminum shear pin is sheared first, causing the valve to move upward and opening the port of the lower sleeve; the copper shear pin is sheared later, and the cement slurry is squeezed out by the piston.

[0018] Furthermore, the impact assembly includes an impact rod and an impact head; a valve is connected to one end of the impact rod, and the impact head is connected to the other end of the impact rod.

[0019] In this design, an impact head is designed at the tail of the impact rod to increase the contact area with the sand and gravel surface. This prevents the impact rod from inserting into the sand and gravel to form a buffer when the pin breaks due to shock, thus avoiding difficulties in breaking the pin.

[0020] Secondly, based on the ash-discharging cylinder for the small-diameter oil pipe provided in the first aspect, the present invention provides a method for discharging ash from a small-diameter oil pipe, comprising the following steps:

[0021] S1: Insert a plug into the oil pipe and pour sand over the plug in preparation for ash removal;

[0022] S2: Fill the cement slurry into the ash-pouring cylinder; connect the tool string with steel wire, the tool string from top to bottom consisting of a rope cap, a weight bar, a vibrator and the ash-pouring cylinder; lower the tool string into the oil pipe;

[0023] S3: Lower the ash pourer to the sand surface position; use the vibrator to vibrate downwards and shear the impact shear pin and piston shear pin backwards; the impact rod and valve move upwards to open the port of the lower sleeve, the piston connecting rod moves downwards under the weight of the weight rod, and pushes the cement slurry from the port into the lower sleeve, and flows out from the slurry outlet on the side of the lower sleeve;

[0024] S4: The limit snap ring moves to the position of the limit ring groove, and the cement slurry is completely squeezed out by the piston; the tool string is pulled out from the oil pipe;

[0025] S5: Determine whether to continue pouring cement based on the height of the preset cement plug; if the height of the cement plug that has been poured is less than the height of the preset cement plug, repeat steps S2-S4 until the pouring operation is completed.

[0026] In this design, a vibrator and a weight bar are designed above the ash discharge cylinder. The vibrator provides a shock effect to shear the impact shear pin and the piston shear pin, which is simple to operate and easy to implement. The weight bar provides downward pressure to the piston, so that the piston moves downward and squeezes out all the cement slurry in the upper sleeve.

[0027] The beneficial effects of this invention are:

[0028] The slurry discharge cylinder for small-diameter oil pipes provided by this invention has a piston installed inside the upper sleeve. The piston's squeezing action pushes the cement slurry out of the upper sleeve, effectively avoiding the problem that the cement slurry cannot flow out naturally due to its strong adhesion. It is suitable for cement slurry delivery in small-diameter oil pipes and can realize double-blocking barrier operation in small-diameter oil pipes during pressurized operations, solving technical problems in the field of pressurized operations and filling a technical gap. An impact rod is installed inside the lower sleeve. The contact between the impact rod and the sand and gravel surface opens the port of the lower sleeve to release the cement slurry.

[0029] In the ash discharge method for small-diameter oil pipes provided by the present invention, the impact shear pin and piston shear pin are cut off by the impact of the vibrator to release the cement slurry, and the cement slurry is pushed out of the sleeve by the gravity of the weight rod. Compared with the existing ash cylinder opening method such as electric blasting, the safety factor is higher and the release of cement slurry is easier to control. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the cross-sectional structure of the ash-pouring cylinder of a small-diameter oil pipe according to the present invention;

[0031] Figure 2 This is a schematic diagram of the valve structure of the present invention;

[0032] Figure 3 This is a schematic diagram of the cement slurry filling structure of the ash-pouring cylinder of the small-diameter oil pipe of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of the small-diameter oil pipe of the present invention after the impact shear pin of the ash-pouring cylinder is cut off.

[0034] Figure 5 This is a schematic diagram of the structure of the ash-pouring cylinder piston shear pin of the small-diameter oil pipe of the present invention after it has been cut off.

[0035] Figure label:

[0036] 1. Connector; 2. Piston assembly; 3. Sleeve cap; 4. Piston shear pin; 5. Limiting snap ring; 6. Piston; 7. Upper sleeve; 8. Valve; 9. Lower sleeve; 10. Impact assembly; 11. Impact shear pin; 12. Slurry outlet; 13. Impact head. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Specific embodiments of the present invention are described below to facilitate understanding by those skilled in the art. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment provides a slurry discharge cylinder for small-diameter oil pipes, suitable for injecting cement slurry into small-diameter oil pipes to form a cement plug; the slurry discharge cylinder is designed with a piston, which pushes the cement slurry into the oil pipe, effectively avoiding the problem of the cement slurry being unable to flow out naturally due to its strong adhesion; specifically, it includes:

[0040] Piston assembly 2, upper sleeve 7, lower sleeve 9 and impact assembly 10;

[0041] The upper sleeve 7 and the lower sleeve 9 are connected and their inner cavities are interconnected. The upper sleeve 7 is equipped with a piston assembly 2. The lower sleeve 9 is equipped with an impact assembly 10. The impact assembly 10 has a valve 8 at one end near the upper sleeve 7, which seals the port of the lower sleeve 9. When the ash-pouring cylinder is placed into the oil pipe, the impact assembly 10 impacts the sand and gravel surface. The impact assembly 10 drives the valve 8 upward to open the port of the lower sleeve 9. The piston assembly 2 moves downward to push the cement slurry inside the upper sleeve 7 to the lower sleeve 9. The cement slurry enters the lower sleeve 9 through the port and flows out from the slurry outlet 12 on the side of the lower sleeve 9, forming a cement plug in the oil pipe.

[0042] The piston assembly 2 includes a piston rod, a piston 6, and a connector 1; one end of the piston rod is connected to the piston 6, and the other end of the piston rod is connected to the connector 1; the end of the piston rod with the piston 6 is located inside the upper sleeve 7, and when the cement slurry is released, the piston 6 squeezes out all the cement slurry in the upper sleeve 7 to avoid cement slurry residue in the upper sleeve 7.

[0043] As a preferred embodiment, a sealing ring is designed on the piston 6 to seal it.

[0044] As a preferred embodiment, the connector 1 has a buckle type that is common to wire cutting tools; and the connector 1 has a retrieval diameter.

[0045] The upper sleeve 7 includes a sleeve body and a sleeve cap 3, which are connected. The piston 6 is located inside the sleeve body. When it is necessary to fill the upper sleeve 7 with cement grout, the sleeve cap 3 is opened, cement grout is filled in, the piston 6 is then placed in, and the sleeve cap 3 is closed. This design facilitates the filling of cement grout during operation.

[0046] The piston 6 is equipped with a limiting snap ring 5, and the bottom of the upper sleeve 7 has a limiting ring groove. When the piston 6 moves to the bottom of the upper sleeve 7, the limiting snap ring 5 is inserted into the limiting ring groove to fix the piston 6. The limiting snap ring 5 is inserted into the limiting ring groove to fix the piston 6 and the upper sleeve 7 into a whole. When the ash dumping is completed and the ash dumping cylinder is lifted out of the oil pipe, the whole can be lifted out quickly. In addition, the limiting snap ring 5 inserted into the limiting ring groove can also ensure that cement slurry will not be sucked back into the chamber during the lifting of the ash dumping cylinder.

[0047] The piston assembly 2 is fixed to the upper sleeve 7 by the piston shear pin 4; the impact assembly 10 is fixed to the lower sleeve 9 by the impact shear pin 11. In actual ash dumping operations, this design allows the ash dumping cylinder to be placed into the oil pipe and impacted downwards to release the impact rod and piston 6, thereby releasing the cement slurry. Compared with the existing explosion method for releasing cement slurry, this design offers greater controllability and safety.

[0048] Piston shear pin 4 is made of copper; impact shear pin 11 is made of aluminum; during impact, the aluminum shear pin is cut first, the valve 8 moves upward, opening the port of the lower sleeve 9; the copper shear pin is cut later, and the cement slurry is squeezed out by the piston 6.

[0049] The impact assembly 10 includes an impact rod and an impact head 13; a valve 8 is connected to one end of the impact rod, and the impact head 13 is connected to the other end of the impact rod; the impact head 13 is designed at the tail of the impact rod to increase the contact area with the sand and gravel surface, so as to prevent the impact rod from inserting into the sand and gravel to form a buffer when the pin breaks due to shock, thus making it difficult to break the pin.

[0050] As a preferred embodiment of this example, Figure 2 As shown, the valve 8 is a cylindrical structure with a slotted upper part; after the impact shear pin 11 is cut off, the valve 8 moves upward and hits the step at the bottom of the upper sleeve 7, and the cement slurry can flow out through the slot in the middle of the valve 8.

[0051] The working principle of this embodiment is as follows:

[0052] In use, cement slurry is first filled into the upper sleeve 7, then a plug is placed in the oil pipe and sand and gravel are laid in; the ash-pouring cylinder is placed into the oil pipe, and the impact rod at the bottom of the ash-pouring cylinder impacts the sand and gravel surface. During the impact, the impact shear pin 11 and the piston shear pin 4 are sheared in sequence; the impact rod pushes the valve 8 to move upward, opening the port of the lower sleeve 9; the piston connecting rod pushes the piston 6 to move downward, pushing the cement slurry inside the upper sleeve 7 to the lower sleeve 9; the cement slurry enters the lower sleeve 9 through the port and flows out from the slurry outlet 12 on the side of the lower sleeve 9, forming a cement plug in the oil pipe.

[0053] Example 2

[0054] This embodiment, based on the ash-discharging cylinder for the small-diameter oil pipe provided in Embodiment 1, provides a method for discharging ash from a small-diameter oil pipe, including the following steps:

[0055] S1: Insert a plug into the oil pipe and pour sand over the plug in preparation for ash removal;

[0056] S2: Fill the cement slurry into the ash-pouring cylinder; connect the tool string with steel wire, the tool string from top to bottom consisting of a rope cap, a weight bar, a vibrator, and the ash-pouring cylinder; lower the tool string into the oil pipe;

[0057] S3: Lower the ash pourer to the sand surface position. At this point, neither the impact shear pin 11 nor the piston shear pin 4 has been shortened. Figure 3 As shown;

[0058] By striking downwards with the shock absorber, the impact shear pin 11 is first sheared off, and the impact rod and valve 8 move upwards to open the port of the lower sleeve 9. Figure 4 As shown;

[0059] Piston shear pin 4 is sheared off; piston connecting rod moves downward under the weight of counterweight rod, pushing cement grout from the port into lower sleeve 9, and out from grout outlet 12 of lower sleeve 9, as shown. Figure 5 As shown;

[0060] S4: The limiting snap ring 5 moves to the position of the limiting ring groove, and the cement slurry is completely squeezed out by the piston 6; the tool string is pulled out from the oil pipe;

[0061] S5: Determine whether to continue pouring cement based on the height of the preset cement plug; if the height of the cement plug that has been poured is less than the height of the preset cement plug, repeat steps S2-S4 until the pouring operation is completed.

[0062] In this embodiment, a vibrator and a weight bar are designed above the ash discharge cylinder. The vibrator provides a shocking action to cut off the impact shear pin 11 and the piston shear pin 4. The operation is simple and easy to implement. The weight bar provides downward pressure to the piston 6, so that the piston 6 moves downward to squeeze out all the cement slurry in the upper sleeve 7.

[0063] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention and should be understood as not limiting the scope of protection of the invention to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed herein without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the invention.

Claims

1. A small-diameter oil pipe ash discharge cylinder, characterized in that: It includes a piston assembly (2), an upper sleeve (7), a lower sleeve (9), and an impact assembly (10); the upper sleeve (7) and the lower sleeve (9) are connected, and the inner cavities of the upper sleeve (7) and the lower sleeve (9) are in communication; the piston assembly (2) is provided inside the upper sleeve (7); the impact assembly (10) is provided inside the lower sleeve (9), and a valve (8) is provided at one end of the impact assembly (10) near the upper sleeve (7), and the valve (8) seals the port of the lower sleeve (9); The piston assembly (2) includes a piston connecting rod, one end of which is provided with a piston (6), and the other end of which is provided with a connector (1); the end of the piston connecting rod with the piston (6) is located inside the upper sleeve (7); The piston (6) is provided with a limiting snap ring (5), and the bottom of the upper sleeve (7) is provided with a limiting ring groove; when the piston (6) moves to the bottom of the upper sleeve (7), the limiting snap ring (5) is embedded in the limiting ring groove to fix the piston (6); The piston assembly (2) is fixed to the upper sleeve (7) by a piston shear pin (4); the impact assembly (10) is fixed to the lower sleeve (9) by an impact shear pin (11); The impact assembly (10) includes an impact rod and an impact head (13); the valve (8) is connected to one end of the impact rod, and the impact head (13) is connected to the other end of the impact rod.

2. The ash-discharging cylinder for a small-diameter oil pipe according to claim 1, characterized in that: The upper sleeve includes a sleeve body and a sleeve cap (3), the sleeve body and the sleeve cap (3) are connected, and the piston (6) is disposed in the sleeve body.

3. The ash-discharging cylinder for a small-diameter oil pipe according to claim 1, characterized in that: The piston shear pin (4) is a copper shear pin; the impact shear pin (11) is an aluminum shear pin.

4. A method for discharging ash using an ash-discharging cylinder with a small-diameter oil pipe as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Insert a plug into the oil pipe and pour sand over the plug in preparation for ash removal; S2: Load cement slurry into the ash-pouring cylinder; connect a tool string with a steel wire, the tool string consisting of a rope cap, a weight bar, a vibrator, and the ash-pouring cylinder from top to bottom; lower the tool string into the oil pipe; S3: Lower the ash pourer to the sand surface position; use the vibrator to vibrate downwards and shear the impact shear pin (11) and piston shear pin (4) backwards; the impact rod and valve (8) move upwards to open the port of the lower sleeve (9), the piston connecting rod moves downwards under the weight of the weight rod, and pushes the cement slurry from the port into the lower sleeve (9), and flows out from the slurry outlet (12) on the side of the lower sleeve (9); S4: The limiting snap ring (5) moves to the position of the limiting ring groove, and the cement slurry is completely squeezed out by the piston (6); the tool string is pulled out from the oil pipe; S5: Determine whether to continue pouring cement based on the height of the preset cement plug; if the height of the cement plug that has been poured is less than the height of the preset cement plug, repeat steps S2-S4 until the pouring operation is completed.

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