Tool for controlling cement return height of well cementation standard layer and use method
By designing a tool to control the cement backflow in standard cementing layers, and utilizing a soluble ball seat that combines a casing sub and a sliding sleeve to control the cement slurry circulation channel, the problem of casing damage caused by cement backflow was solved, achieving effective protection of the casing and extending its service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2026-04-03
AI Technical Summary
Existing cement return exceeding the standard layer has led to casing damage, especially under the requirement of full well sealing, where existing tools cannot meet the construction requirements, resulting in a high casing damage rate.
Design a tool for controlling the cement return height of standard cementing layers. By cooperating with the casing sub and the sliding sleeve, the tool utilizes the soluble properties to open and close the ball seat to control the circulation channel of the cement slurry, thereby precisely controlling the amount of cement return height and reducing casing damage.
By precisely controlling the cement backflow, damage to the casing is reduced, the service life of the casing is extended, and subsequent construction is not affected.
Smart Images
Figure CN121781882A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oilfield drilling, specifically to a tool and method for controlling the cement return height of standard cementing layers. Background Technology
[0002] During oilfield construction, casing damage can cause significant production losses and severely impact oilfield output. Taking Daqing Oilfield as an example, casing damage is mainly characterized by deformation and faulting, primarily occurring in the Nenjiang No. 2 bottom oil shale standard layer and the Sapu oil layer. Standard layer casing damage accounts for a substantial proportion of 23.86% to 37.3% of total casing damage. The standard layer lithology is oil shale, which has particularly well-developed horizontal bedding. After significant water ingress, water will flow along the bedding planes, thereby disrupting the structure and stability of the rock formation. When there is a large pressure difference between the upper and lower layers of the rock formation or an imbalance in circumferential pressure in local areas, creeping slippage will occur between the bedding planes. If the formation is in rigid contact with the casing at this point, the casing can be directly damaged.
[0003] When studying and analyzing casing damage in oilfields, it was concluded that the damage was caused by a short cement-sealed section, and that full well sealing was necessary. Similar reports and field trials have been conducted both domestically and internationally. To verify this, Daqing Oilfield's No. 1 Oil Production Plant conducted a test on 16 wells in a block. Thirteen wells were fully sealed, while three wells had cement return heights below the standard layer due to incomplete sealing. The test results showed that the casings in the 13 fully sealed wells were completely damaged, all within the standard layer of the Nenjiang No. 2 bottom oil shale, while the casings in the three incompletely sealed wells remained undamaged. Practice has proven that whether the cement return height exceeds the standard layer is the key and primary indicator of casing damage in this location.
[0004] Currently, cement face control tools are available in oil fields. These tools provide flexible sealing for standard casing sections. However, under the requirement of full well sealing, the closing control of cement face control tools cannot meet the requirements of on-site construction. Summary of the Invention
[0005] To overcome the shortcomings of existing cementing methods that cause casing damage due to cement return exceeding the standard layer, this invention provides a tool and method for controlling cement return at the standard cementing layer. This tool can precisely control the amount of cement slurry displaced in the annulus, thereby controlling cement return and reducing casing damage.
[0006] The technical solution of the present invention is: a tool for controlling the cement return height of a standard cementing layer, comprising a casing short section, the lower end of which is connected to an upper conversion joint, the lower end of which is externally connected to a body, the body being internally connected to a sliding sleeve via a sliding sleeve shear pin, the sliding sleeve being internally connected to an opening ball seat via an opening ball seat shear pin, the upper end of which is provided with a closing ball seat, an opening ball above the opening ball seat, and a closing ball above the closing ball seat.
[0007] Furthermore, the main body has several main body circulation holes on its side wall and the sliding sleeve has several sliding sleeve circulation holes on its side wall. When the tool is in its initial position, the main body circulation holes and the sliding sleeve circulation holes are connected.
[0008] Furthermore, the inner wall of the upper end of the opening ball seat is an inclined surface, and the opening ball cooperates with the inclined surface of the opening ball seat.
[0009] Furthermore, the inner wall of the upper end of the closing ball seat is inclined, and the closing ball cooperates with the inclined surface of the closing ball seat.
[0010] Furthermore, the diameter of the opening ball is smaller than the inner diameter of the closing ball seat.
[0011] Furthermore, both the opening and closing ball seats are made of soluble materials.
[0012] Furthermore, the sleeve short section is connected to the upper conversion joint via the upper short sleeve.
[0013] Furthermore, the lower end of the main body is connected to a lower conversion connector, and the lower end of the lower conversion connector is connected to a lower short sleeve.
[0014] Furthermore, several sealing rings are provided between the body and the sliding sleeve. When the circulation hole of the body and the circulation hole of the sliding sleeve are misaligned, the sealing rings will seal the body and the sliding sleeve.
[0015] A method of using the tool for controlling the cement return height of a standard cementing layer, as described above, involves the following steps after cementing: After cementing, an opening ball is inserted. Once the opening ball falls onto the opening ball seat, pressure is increased to shear the shear pin of the opening ball seat. The opening ball seat descends, exposing the body circulation hole and the sliding sleeve circulation hole. After circulating drilling fluid to the calculated volume, a closing ball is inserted. Once the closing ball falls onto the closing ball seat, pressure is increased to shear the shear pin of the sliding sleeve, causing the sliding sleeve to descend and seal the body circulation hole on the body, thereby closing the circulation channel.
[0016] This invention offers the following advantages: Due to the aforementioned design, the tool's main body circulation hole and sliding sleeve circulation hole are connected in the initial position, forming a circulation channel. The sliding sleeve is connected to the opening ball seat via an opening ball seat shear pin. During ball insertion, the opening ball seat can be knocked off, thereby opening the circulation channel for drilling fluid circulation. After the closing ball is inserted, the sliding sleeve shear pin is cut, and the sliding sleeve descends, closing the circulation hole on the main body and shutting down the circulation channel, thus controlling cement backflow. This tool precisely controls the amount of cement slurry displaced in the annulus, thereby reducing casing damage and extending casing service life. Furthermore, both the opening and closing ball seats are made of soluble materials, which automatically decompose after immersion in water, ensuring that the internal diameter of the casing does not affect subsequent construction operations. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the present invention;
[0018] Figure 2 This is a schematic diagram of the body and the sliding sleeve when the circulation channel is open;
[0019] Figure 3 This is a schematic diagram of the body and the sliding sleeve when the circulation channel is closed.
[0020] In the diagram, 1-sleeve short section, 2-upper short sleeve, 3-upper adapter, 4-closing ball seat, 5-body, 6-sliding sleeve, 7-opening ball seat, 8-closing ball, 9-opening ball, 10-lower adapter, 11-lower short sleeve, 12-body circulation hole, 13-sliding sleeve circulation hole, 14-sliding sleeve seat shear pin, 15-opening ball seat shear pin. Detailed Implementation
[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] In the description of this invention, it is necessary to understand that the orientations or positional relationships indicated by terms such as "upper," "lower," "left," "right," "inner," "outer," "top," and "bottom" are based on the orientations or positional relationships shown in the accompanying drawings. They are intended only to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the components referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0023] Depend on Figure 1 As shown, a tool for controlling cement return in standard cementing layers includes a casing sub 1, which is used to connect the tool to the casing. The lower end of the casing sub 1 is connected to an upper short casing 2, and the lower end of the upper short casing 2 is connected to an upper adapter 3. The upper adapter 3 has an internal thread at its upper end, connecting to the upper short casing 2, and an external thread at its lower end, connecting to a body 5. The outer surface of the body 5 is flush with the outer surface of the upper adapter 3, and a sealing ring is provided at their connection. The lower end of the body 5 is connected to a lower adapter 10, and the lower end of the lower adapter 10 is connected to a lower short casing 11. Similarly, a sealing ring is provided between the body 5 and the lower adapter 10.
[0024] The main body 5 has a sliding sleeve 6 inside, which can slide up and down inside the main body 5. The sliding sleeve 6 is connected to the main body 5 by a sliding sleeve shear pin 14. When the pressure on the sliding sleeve 6 reaches the shear pressure limit of the sliding sleeve shear pin 14, the sliding sleeve shear pin 14 will shear off. Several through holes are opened on the side wall of the main body 5, which are the main body circulation holes 12. Similarly, several through holes are opened on the side wall of the sliding sleeve 6, which are the sliding sleeve circulation holes 13. In the initial position of the tool, the main body circulation holes 12 and the sliding sleeve circulation holes 13 are connected to provide a circulation channel for cement slurry. Figure 2 When the tool is in the closed position, the body circulation hole 12 and the sliding sleeve circulation hole 13 are misaligned, thereby closing the cementing slurry channel. (See...) Figure 3 Several sealing rings are provided between the body 5 and the sliding sleeve 6. The sealing rings are distributed on the upper and lower sides of the circulation hole 13 of the sliding sleeve, with a certain distance in the vertical direction. Two sealing rings are provided on each of the upper and lower sides of the circulation hole 13 of the sliding sleeve, ensuring that when the circulation hole 12 of the body and the circulation hole 13 of the sliding sleeve are connected, there are sealing rings on both the upper and lower sides, thereby ensuring that the circulation channel is unobstructed. At the same time, when the tool is in the closed position, the circulation hole 12 of the body and the circulation hole 13 of the sliding sleeve are respectively between two sealing rings, ensuring that the circulation hole 12 of the body is sealed and the sealing is reliable. The inner diameter of the sliding sleeve 6 is not less than the inner diameter of the lower conversion joint 10, so that when the sliding sleeve 6 moves downward, it can fall on the lower conversion joint 10, preventing the sliding sleeve 6 from continuing to slide downward. At the same time, the inner diameter of the sliding sleeve 6 is large enough not to affect the inner diameter of the pipe.
[0025] The sliding sleeve 6 has an opening ball seat 7 inside, which can slide up and down within the sliding sleeve 6. The opening ball seat 7 is connected to the lower end of the sliding sleeve 6 via an opening ball seat shear pin 15. Preferably, the bottom of the opening ball seat 7 is flush with the bottom surface of the sliding sleeve 6. The outer diameter of the opening ball seat 7 is smaller than the inner diameter of the lower adapter 10, allowing it to pass through the lower adapter 10 and fall into the lower pipe column after being knocked off. An opening ball 9 is provided on the upper part of the opening ball seat 7. The inner wall of the upper end of the opening ball seat 7 is inclined, allowing the opening ball 9 to land on the opening ball seat 7 after being dropped. This, combined with the inclined surface of the upper end of the opening ball seat 7, allows the opening ball 9 to seal the central channel. A sealing ring is also provided between the sliding sleeve 6 and the opening ball seat 7 to ensure a tight seal.
[0026] There is a gap between the upper end face of the sliding sleeve 6 and the lower end face of the upper adapter 3. A closing ball seat 4 is provided at the upper end of the sliding sleeve 6, and a boss is provided on the outer surface of the closing ball seat 4. The boss is located between the upper end face of the sliding sleeve 6 and the lower end face of the upper adapter 3, thereby pressing the closing ball seat 4 tightly onto the sliding sleeve 6 by the upper adapter 3. A closing ball 8 is provided above the closing ball seat 4. Similarly, the inner wall of the upper end of the closing ball seat 4 is provided with an inclined surface, and the closing ball seat 4 and the closing ball 8 are engaged through the inclined surface.
[0027] To ensure that the opening ball 9 can smoothly pass through the closing ball seat 4 and fall onto the opening ball seat 7, the diameter of the opening ball 9 should be smaller than the inner diameter of the closing ball seat 4, and also smaller than the inner diameter of the upper conversion joint 3. Both the opening ball seat 7 and the closing ball seat 8 are made of soluble materials and will automatically decompose after being soaked in well fluid for 96 hours, ensuring the pipe's internal diameter and not affecting subsequent construction operations.
[0028] When connecting the tool, apply lubricant to the outside of the open ball seat 7 and install the sealing ring. Insert the open ball seat 7 into the sliding sleeve 6, connecting them with the open ball seat shearing pin 15. Install the sealing ring on the sliding sleeve 6, apply lubricant to the outside, and install it into the body 5. Install the close ball seat 4 into the body 5, and connect the upper adapter 3 and the lower adapter 10 to both ends of the body 5. Then connect the upper short sleeve 2 and the lower short sleeve 11, and finally connect the sleeve short section 1 to the upper short sleeve 2. The installation is now complete.
[0029] A method for using a tool to control the cement return height of standard cementing layers:
[0030] The tool is lowered into the designed position inside the wellbore. After cementing, the opening ball 9 is deployed. Once the opening ball 9 falls onto the opening ball seat 7, the central channel is sealed. Pressure is increased to shear the opening ball seat shear pin 15, causing the opening ball seat 7 to disengage from the sliding sleeve 6 and descend into the lower tubing string, exposing the main body circulation hole 12 and the sliding sleeve circulation hole 13. At this point, the main body circulation hole 12 and the sliding sleeve circulation hole 13 are connected. Figure 2 As shown, the drilling fluid is circulated until the calculated volume is reached. Then, the shut-off ball 8 is inserted. After the shut-off ball 8 falls onto the shut-off ball seat 4, the pressure is increased to shear the sliding sleeve shear pin 14, causing the sliding sleeve 6 to disengage from the body 5 and descend, falling to the upper end of the lower conversion joint 10 below, sealing the body circulation hole 12 on the body 5, as shown. Figure 3 As shown, this closes the loop channel.
[0031] In its initial position, the tool's main body circulation hole and the sliding sleeve circulation hole are connected, forming a circulation channel. Inside the sliding sleeve, an opening ball seat is connected to a shear pin. During ball insertion, the opening ball seat is knocked off, opening the circulation channel for drilling fluid circulation. After the closing ball is inserted, the sliding sleeve shear pin is cut, and the sliding sleeve descends, closing the circulation hole on the main body and shutting down the circulation channel, thus controlling cement backflow. This tool precisely controls the amount of cement slurry displaced in the annulus, thereby controlling cement backflow, reducing casing damage, and extending casing life. Furthermore, both the opening and closing ball seats are made of soluble materials and automatically decompose after immersion in water, ensuring that the internal diameter of the casing does not affect subsequent construction operations.
[0032] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A tool for controlling cement return in standard cementing layers, comprising a casing sub (1), characterized in that: The lower end of the sleeve short section (1) is connected to the upper conversion joint (3), the lower end of the upper conversion joint (3) is externally connected to the body (5), the body (5) is internally connected to the sliding sleeve (6) through the sliding sleeve shear pin (14), the sliding sleeve (6) is internally connected to the opening ball seat (7) through the opening ball seat shear pin (15), the upper end of the sliding sleeve (6) is provided with the closing ball seat (4), the opening ball (9) is provided above the opening ball seat (7), and the closing ball (8) is provided above the closing ball seat (4).
2. The tool for controlling the cement return height of standard cementing layers according to claim 1, characterized in that: The main body (5) has several main body circulation holes (12) on its side wall, and the sliding sleeve (6) has several sliding sleeve circulation holes (6) on its side wall. When the tool is in its initial position, the main body circulation holes (12) and the sliding sleeve circulation holes (13) are connected.
3. The tool for controlling the cement return height of standard cementing layers according to claim 2, characterized in that: The upper inner wall of the opening ball seat (7) is an inclined surface, and the opening ball (9) is matched with the inclined surface of the opening ball seat (7).
4. The tool for controlling the cement return height of standard cementing layers according to claim 3, characterized in that: The inner wall of the upper end of the closing ball seat (4) is inclined, and the closing ball (8) is matched with the inclined surface of the closing ball seat (4).
5. The tool for controlling the cement return height of standard cementing layers according to claim 4, characterized in that: The diameter of the opening ball (9) is smaller than the inner diameter of the closing ball seat (4).
6. The tool for controlling the cement return height of standard cementing layers according to claim 5, characterized in that: Both the open ball seat (7) and the close ball seat (4) are made of soluble materials.
7. The tool for controlling the cement return height of standard cementing layers according to claim 6, characterized in that: The sleeve short section (1) and the upper conversion joint (3) are connected by the upper short sleeve (2).
8. The tool for controlling the cement return height of standard cementing layers according to claim 7, characterized in that: The lower end of the main body (5) is connected to the lower conversion connector (10), and the lower end of the lower conversion connector (10) is connected to the lower short sleeve (11).
9. The tool for controlling the cement return height of standard cementing layers according to claim 8, characterized in that: Several sealing rings are provided between the body (5) and the sliding sleeve (6). When the circulation hole (12) of the body and the circulation hole (13) of the sliding sleeve are misaligned, the sealing rings seal the body (5) and the sliding sleeve (6).
10. A method of using a tool for controlling cement return height in standard cementing layers according to any one of claims 1-9, characterized in that: After cementing, the opening ball (9) is inserted. After the opening ball (9) falls onto the opening ball seat (7), the pressure is increased, and the opening ball seat (7) shears the opening ball seat shear pin (15). The opening ball seat (7) moves downward, exposing the body circulation hole (12) and the sliding sleeve circulation hole (13). After the drilling fluid is circulated to the calculated volume, the closing ball (8) is inserted. After the closing ball (8) falls into the closing ball seat (4), the pressure is increased to shear the sliding sleeve shear pin (14). The sliding sleeve (6) moves downward, sealing the body circulation hole (12) on the body (5), thereby closing the circulation channel.