A roller cone back reaming bit

Abstract

The application discloses a roller follow-up pipe drilling head and belongs to the technical field of follow-up pipe drilling. The roller follow-up pipe drilling head comprises a rod body, a roller bit connected to the end of the rod body, a plurality of centralizing plates arranged on the side of the rod body away from the roller bit in a circumferential direction, a baffle ring arranged outside the centralizing plates, a plurality of pairs of limiting locks arranged on the side of the rod body close to the roller bit in a circumferential direction, a limiting pin rotatably arranged on each pair of limiting locks, and a scraper plate connected to the limiting pin. The roller follow-up pipe drilling head is suitable for follow-up pipe drilling construction of special strata such as soil, silt and pebble which are extremely easy to collapse and difficult to form a hole. The roller follow-up pipe drilling head can realize the function of simultaneous drilling of a casing and a drill bit and avoid the defects of low efficiency, difficult residue discharge and casing fracture caused by the air follow-up pipe drilling process.

Description

Technical Field

[0001] This invention relates to a roller cone casing drill bit, belonging to the field of casing drilling technology. Background Technology

[0002] As drilling depths increase and downhole conditions become more complex, drilling techniques must become more diversified to adapt to deep well operations. Currently, domestic drilling techniques primarily utilize mud circulation and air circulation. For conventional surface drilling, air-casing drilling is commonly employed. Air-casing drilling uses high-pressure air as its power source, employing a down-the-hole hammer to break up the formation and blow cuttings to the surface. This allows for simultaneous drilling of the casing and drill bit, and is highly efficient in stable formations. However, because air-casing drilling relies on high-pressure air, it becomes inefficient in challenging formations such as soil, silt, and gravel, where collapse is likely and drilling is difficult. Problems include difficulty in removing cuttings and even the possibility of borehole collapse leading to casing breakage. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a roller cone casing drill bit that can realize the function of drilling casing and drill bit at the same time, while avoiding the defects of low efficiency, difficulty in slag removal and casing breakage caused by air casing drilling process.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A roller cone and casing drill bit includes a rod body, with a roller cone drill bit connected to the end of the rod body. A plurality of straightening plates are circumferentially arranged on the side of the rod body away from the roller cone drill bit, and a retaining ring is provided on the outer side of the straightening plates. A plurality of pairs of limit locks are circumferentially arranged on the side of the rod body near the roller cone drill bit, and a limit pin is rotatably provided on each pair of limit locks. A scraper plate is connected to the limit pin.

[0006] The outer diameter of the retaining ring is greater than the maximum inner diameter of the casing shoe step and less than the inner diameter of the casing; the diameter of the scraper blade when it is extended is greater than the outer diameter of the casing, and the diameter when it is retracted is less than the minimum inner diameter of the casing shoe; the diameter of the roller cone drill bit is less than the minimum inner diameter of the casing shoe.

[0007] The diameter of the scraper blade when unfolded is the same as the diameter of the roller cone drill bit.

[0008] The limiting lock has a cylindrical semi-open structure. The limiting lock is provided with a limiting lock hole and a limiting lock limit. The limiting pin passes through the limiting lock hole of each pair of limiting locks. When the scraper plate is unfolded, it contacts the limiting lock.

[0009] The rod body and the roller cone drill bit are connected by a threaded connection.

[0010] A flat groove is milled on the end side of the rod away from the roller cone drill bit.

[0011] The scraper blade is provided with alloy teeth at its end.

[0012] The rod and the straightening plate are connected by welding.

[0013] The straightening plate and the retaining ring are connected by welding.

[0014] The limiting pin and the scraper plate are connected by welding.

[0015] The beneficial effects of this invention: This invention provides a roller cone casing drill bit, with a roller cone drill bit connected to the end of the rod body. Several circumferentially arranged centering plates are provided on the side of the rod body, and retaining rings are provided on the outer sides of the centering plates. Several pairs of limit locks are arranged circumferentially on the rod body, with a limit pin rotatably mounted on each pair of limit locks. A scraper plate is connected to the limit pin. This invention transforms mud drilling into casing drilling, with the same principle as air drilling tools. It uses casing and casing shoe welding. In use, the drill bit is inserted into the casing, and then the limit block is opened by rotating clockwise. The casing shoe step and... If the casing drill bit gets stuck, after drilling is completed, reverse the casing drill bit and pull it out of the casing. This drill bit can meet the current special strata casing drilling construction in soil, silt, pebbles and other special strata that are very easy to collapse and difficult to drill. Compared with traditional air casing drilling construction, roller cone casing drill bit can use mud drilling. In soil, silt and other strata conditions, it solves the construction problems of low efficiency, no slag removal and no mud wall protection of air casing drilling, which greatly improves the construction success rate. At the same time, this process eliminates the use of air compressor and reduces construction costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a roller cone follower drill bit according to the present invention;

[0017] Figure 2 This is a schematic diagram of the casing drilling tool in this invention;

[0018] Figure 3 This is a schematic diagram of the structure of the limiting pin and the scraper plate in this invention;

[0019] Figure 4 This is a schematic diagram of the limit lock in this invention;

[0020] Figure 5 This is a schematic diagram of the roller cone drill bit in this invention;

[0021] The markings in the diagram are as follows: 1-rod body; 2-straightening plate; 3-retaining ring; 4-limiting pin; 5-scraper plate; 6-limiting lock; 7-roller cone drill bit; 11-flat groove; 501-alloy tooth; 601-limiting lock hole; 602-limiting lock limit. Detailed Implementation

[0022] Example 1

[0023] like Figure 1 As shown, this invention discloses a roller cone casing drill bit, mainly comprising two parts: a casing drill tool and a roller cone drill bit 7. The casing drill tool includes a rod body 1, a straightening plate 2, a retaining ring 3, a limiting pin 4, a scraper plate 5, and a limiting lock 6. The roller cone drill bit 7 is connected to the end of the rod body 1. Several straightening plates 2 are circumferentially arranged on the side of the rod body 1 away from the roller cone drill bit 7, and the straightening plates 2 serve to guide and straighten the drill tool. A retaining ring 3 is arranged on the outer side of the straightening plate 2. The outer diameter of the retaining ring 3 can be locked with the casing shoe step, so that the casing and the casing drill bit drill simultaneously during drilling. Several pairs of limiting locks 6 are circumferentially arranged on the side of the rod body 1 near the roller cone drill bit 7. A limiting pin 4 is rotatably arranged on each pair of limiting locks 6, and a scraper plate 5 is connected to the limiting pin 4. When the limiting lock 6 is working, it can prevent the scraper plate 5 from being fully opened when the drill tool rotates forward and closed when it rotates backward, so that the casing drill bit can be completely pulled out of the casing.

[0024] The working principle of this invention is as follows: During operation, the casing drill bit is inserted into the casing with the welded casing shoe, and the roller cone drill bit 7 and scraper plate 5 are completely exposed until the retaining ring 3 locks the casing shoe. The drill bit is rotated forward, and the scraper plate 5 is fully opened by the limiting lock 6, and drilling begins. Drilling causes the roller cone drill bit 7 and scraper plate 5 to break up the formation simultaneously, and the hole diameter will be slightly larger than the outer diameter of the casing. The casing follows the drill bit in real time. When the bedrock is reached, the drill bit is reversed, and the scraper plate 5 is retracted. The maximum diameter of the retracted scraper plate 5 is smaller than the inner diameter of the casing shoe, and the casing drill bit can be smoothly pulled out of the hole, while the casing remains in the hole, thus realizing the use of mud for casing drilling.

[0025] This invention modifies mud drilling to include casing drilling, operating on the same principle as air drilling tools. Compared to traditional air casing drilling, roller cone casing drill bits can use mud drilling and solve construction problems such as low efficiency, lack of slag removal, and inability to use mud for wall protection in soil, silt, and other geological conditions, greatly improving the success rate of construction. At the same time, this process eliminates the need for air compressors, reducing construction costs.

[0026] Example 2

[0027] like Figure 1 As shown, this invention discloses a roller cone casing drill bit, mainly comprising two parts: a casing drill tool and a roller cone drill bit 7. The casing drill tool includes a rod body 1, a centering plate 2, a retaining ring 3, a limiting pin 4, a scraper plate 5, and a limiting lock 6. The roller cone drill bit 7 is connected to the end of the rod body 1, and the structure of the roller cone drill bit 7 is as follows. Figure 5As shown, the diameter of the roller cone bit 7 is smaller than the minimum inner diameter of the casing shoe, ensuring that the roller cone bit 7 can freely enter and exit the casing shoe. The rod body 1 is connected to the roller cone bit 7 by a threaded connection. A flat groove 11 is milled on the side of the rod body 1 away from the roller cone bit 7 to facilitate the disassembly of the drill bit. Four sets of straightening plates 2 are circumferentially arranged on the side of the rod body 1 away from the roller cone bit 7. The straightening plates 2 serve to guide and straighten the drill bit. The rod body 1 and the straightening plates 2 are connected by welding.

[0028] A retaining ring 3 is provided on the outer side of the straightening plate 2, and the straightening plate 2 and the retaining ring 3 are connected by welding. The outer diameter of the retaining ring 3 is larger than the maximum inner diameter of the casing shoe step and smaller than the inner diameter of the casing. The outer diameter of the retaining ring 3 can be locked with the casing shoe step to prevent the casing shoe from passing through the casing drill bit. During drilling, the casing and the casing drill bit drill simultaneously. Three pairs of limit locks 6 are circumferentially provided on the side of the rod body 1 near the roller cone drill bit 7. During operation, the limit locks can restrict the scraper plate from fully opening and closing. Each pair of limit locks 6 is rotatably provided with a limit pin 4, and a scraper plate 5 is connected to the limit pin 4. The limit pin 4 and the scraper plate 5 are connected by welding. Figure 2 and Figure 3 As shown, the scraper blade 5 has alloy teeth 501 welded to its end. During drilling, these teeth will cut the uncut portion of the roller cone drill bit 7, thus ensuring that the borehole diameter is larger than the casing diameter and that the casing follows the drill bit in real time without being affected by formation resistance. When the limit lock 6 is in operation, it can restrict the scraper blade 5 from being fully opened when the drill bit rotates forward and closed when it rotates backward, allowing the casing drill bit to be completely pulled out of the casing.

[0029] like Figure 4 As shown, the limit lock 6 is a cylindrical semi-open structure. The limit lock 6 has a limit lock hole 601 and a limit lock limit 602. The limit pin 4 passes through the limit lock hole 601 of each pair of limit locks 6. When the drill bit rotates forward, the scraper plate 5 is unfolded by the friction of the formation. When unfolded, the scraper plate 5 contacts the limit lock limit 602, and can be unfolded to its maximum diameter, where it is limited by the limit lock limit 602. When the scraper plate 5 is unfolded, its diameter is larger than the outer diameter of the casing. When the drill bit rotates in reverse, the scraper plate retracts due to the friction of the formation. When retracted, its diameter is smaller than the minimum inner diameter of the casing shoe, ensuring passage through the casing shoe. The diameter of the scraper plate 5 when unfolded is the same as the diameter of the roller cone bit 7.

[0030] During construction, the drill bit is inserted into the casing with a welded casing shoe, and the drill bit and scraper are fully exposed until the retaining ring locks the casing shoe. The drill string is rotated forward, and the scraper is fully opened by the limit lock, allowing drilling to begin. Drilling causes the roller cone drill bit and scraper to break up the formation simultaneously, resulting in a hole diameter larger than the outer diameter of the casing. The casing can follow the drill string in real time. When the target depth is reached, the drill string is reversed, and the scraper is retracted. The maximum diameter of the retracted scraper is smaller than the inner diameter of the casing shoe, allowing the drill bit to be smoothly pulled out of the hole, while the casing remains inside. This enables drilling with mud for casing.

[0031] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A roller cone and casing drill bit, characterized in that: The drill bit includes a rod body (1), with a roller cone drill bit (7) connected to its end. Several centering plates (2) are circumferentially arranged on the side of the rod body (1) away from the roller cone drill bit (7). A retaining ring (3) is provided on the outer side of each centering plate (2). The outer diameter of the retaining ring (3) is larger than the maximum inner diameter of the casing shoe step and smaller than the inner diameter of the casing. Several pairs of limit locks (6) are circumferentially arranged on the side of the rod body (1) near the roller cone drill bit (7). Each pair of limit locks (6) is rotatably equipped with a limit pin (4). A scraper plate (5) is connected to the limit pin (4). The scraper plate (5) has alloy teeth (501) at its end. When the drill bit rotates forward, the friction of the formation causes the drill bit to rotate. The scraper blade (5) is unfolded and can be fully opened by the limiting lock (6). When the scraper blade (5) is unfolded, its diameter is larger than the outer diameter of the casing. When drilling to the bedrock, the drill bit is reversed and the scraper blade (5) is retracted. When retracted, its diameter is smaller than the minimum inner diameter of the casing shoe. The diameter of the roller cone drill bit (7) is smaller than the minimum inner diameter of the casing shoe. The limiting lock (6) is a cylindrical semi-open structure. The limiting lock (6) is provided with a limiting lock hole (601) and a limiting lock limit (602). The limiting pin (4) passes through the limiting lock hole (601) of each pair of limiting locks (6). When the scraper blade (5) is unfolded, it contacts the limiting lock limit (602).

2. The roller cone and casing drill bit according to claim 1, characterized in that: When the scraper blade (5) is unfolded, its diameter is the same as that of the roller cone drill bit (7).

3. The roller cone and casing drill bit according to claim 1, characterized in that: The rod body (1) and the roller cone drill bit (7) are connected by a threaded connection.

4. The roller cone and casing drill bit according to claim 1, characterized in that: A flat groove (11) is milled on the end side of the rod (1) away from the roller drill bit (7).

5. The roller cone and casing drill bit according to claim 1, characterized in that: The rod (1) and the straightening plate (2) are connected by welding.

6. The roller cone follower drill bit according to claim 1, characterized in that: The straightening plate (2) and the retaining ring (3) are connected by welding.

7. The roller cone and casing drill bit according to claim 1, characterized in that: The limiting pin (4) and the scraper plate (5) are connected by welding.

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