Three-wing rotary knife structure, system and construction method for cutting in drilling rod for sinking deep well by drilling method

Abstract

The invention discloses a three-wing rotary knife structure, system and construction method for cutting in a drilling-method sinking deep well drilling rod, and belongs to the field of drilling mechanical engineering. In order to solve the problems of large vibration, low precision and poor safety during well bottom cutting after a drill rod is broken, the structure comprises a cutter head, a three-wing rotary cutter capable of being centrifugally thrown out and a split type guider, the three-wing rotary knife is mounted in a staggered tooth manner to realize variable-diameter cutting, so that clamping is prevented, and the stability is improved; the split type guider is provided with a rubber guide wheel which is used for absorbing vibration and reducing abrasion of the rod piece and the guider; the construction method is based on vibration response analysis of a drill rod-cutter system, and the optimal mounting positions and number of the guiders are calculated and determined, so that vibration is effectively inhibited; according to the invention, efficient, stable and safe operation of cutting in the deep well drill rod is realized.

Description

Technical Field

[0001] This invention relates to the field of drilling machinery engineering technology, and in particular to the structure, system and construction method of a three-wing rotary cutter for cutting inside the drill pipe in deep well drilling. Background Technology

[0002] As coal resources are explored at greater depths, the coal industry has higher requirements for well depth and efficiency. Traditional well-drilling methods, such as grouting and drill-and-blast, suffer from drawbacks including high labor intensity and poor safety, failing to meet the modern requirements of less manpower and greater safety. Specialized well-drilling methods include freezing and drilling. The freezing method first uses a refrigerant to freeze the formation to increase its strength and impermeability, then drills and blasts to excavate the wellbore. Drilling, on the other hand, involves power equipment and personnel on the surface, without needing to penetrate deep into the wellbore. It uses depressurized drilling and mud washing to excavate the wellbore, offering advantages such as high mechanization, a better working environment, and superior well quality. However, when drilling into the western Jurassic strata, severe drill bit swaying has occurred, increasing the risk of drill pipe breakage. Therefore, quickly cutting the bottom section of the pipe structure after drill pipe breakage is crucial for improving the efficiency of retrieving the drill bit from the bottom of the well.

[0003] However, research indicates that most cutting tools and methods for cutting the inside of deep drill pipes, both domestically and internationally, are concentrated in the oil drilling industry, with few precedents for cutting drill pipes from the inside. Furthermore, the mechanical components, formations, and mud environment of well drilling methods differ significantly from those in the oil drilling industry, making it impossible to directly apply their drill pipe cutting tools and processes. Therefore, this invention provides a three-wing rotary cutter structure, system, and method for cutting the inside of drill pipes in deep wells using the drilling method, aiming to solve existing technical problems. Summary of the Invention

[0004] The main objective of this invention is to provide a three-wing rotary cutter structure, system, and method for internal cutting of drill pipe in deep well drilling, aiming to solve existing technical problems.

[0005] To achieve the above objectives, the present invention provides a three-wing rotary cutter structure for internal cutting of drill pipe in deep well drilling methods, comprising: Cutterhead drill rod connector; A cutter head, which is connected to the cutter head drill rod joint, the cutter head includes upper and lower cutter housings and multiple wing plates connecting the upper and lower cutter housings, and mounting holes are provided on the cutter housings; There are multiple three-wing rotary cutters. Each three-wing rotary cutter is rotatably mounted in the mounting hole of the cutter housing via a cutter shaft and can rotate around the cutter shaft and revolve around the center of the cutter disc under external force. Each three-wing rotary cutter includes a cutter body, a cutter plate fixed on the cutter body, and multiple cutter teeth mounted on the cutter plate. Furthermore, the plurality of cutting teeth are installed in a staggered manner in the radial direction on the cutting plate. Furthermore, the material of the cutting teeth is YS2T / 325 alloy. Furthermore, the blade plate is provided with a plurality of grooves for mounting the blade teeth, and the blade teeth are fixed in the grooves by brazing.

[0006] A system for internal cutting of deep well drill pipe, characterized in that it comprises: The aforementioned three-wing rotary cutter structure; At least one split-type guide is used to stably drive the drill rod of the three-wing rotary cutter structure during cutting.

[0007] Furthermore, the split guide includes two split guide discs that can be joined together to form a whole. Each split guide disc includes a guide semicircular plate, a guide wing plate connecting the guide semicircular plate, and a guide wheel mounting hole provided on the guide semicircular plate. The split guide also includes a guide wheel mounted in the guide wheel mounting hole by a vertical bolt, and a transverse bolt for connecting the two split guide discs. Furthermore, the split guide plate also includes a guide slurry hole provided on the guide semicircular plate. Furthermore, the guide wheel is made of rubber.

[0008] A method for deep well drill pipe in-spinning using the system described above includes the following steps; S1: Design and manufacture a cutting disc containing a three-bladed rotary cutter, and conduct indoor cutting tests to verify and optimize the design; S2: Prepare the on-site work area and related equipment; S3: Perform maintenance and repair on relevant components of the drilling rig; S4: Install the three-wing rotary cutter; S5: Lower the assembled three-wing rotary cutter structure and at least one split-type guide into the predetermined cutting position inside the drill pipe, wherein the split-type guide is installed at a specific position driving the drill pipe; S6: Start the cutting operation, initially using a low speed, and gradually increase to the working speed after the system stabilizes; S7: After cutting for a period of time, retract the tool by rotating it forward at a low speed and using a jogging motion. S8: Lift the drill pipe at a constant speed and monitor the lifting process; S9: Check the cutting depth and tool wear. If the cut is not completely made, repeat steps S4 to S9. S10: After cutting, clean up the site.

[0009] Furthermore, in step S5, the installation position of the split guide is determined by calculation through the following steps; Obtain basic parameters including mud properties, drill pipe parameters, cutter parameters, and material properties; Based on the aforementioned basic parameters, the fluid excitation force generated by the three-wing rotary cutter when rotating in a mud environment is calculated; The drill pipe is simplified into a beam model with a fixed top and a concentrated mass at the bottom, and the vibration amplitude at the cutter is calculated when there is no guide. Based on the first and second mode characteristics of the drill pipe, determine the installation position of the guide that can effectively suppress the main vibration.

[0010] The beneficial effects of this invention are reflected in: This invention addresses the challenge of bottom hole treatment after drill pipe breakage during well drilling, creatively proposing a solution for cutting from the inside of the drill pipe. This solution, along with its dedicated three-wing rotary cutter structure, effectively overcomes the limitations of oil drilling tools and processes that are unsuitable for the mud environment, components, and formations of coal mine drilling. It provides a highly efficient and reliable cutting method specifically designed for this scenario, filling a technological gap in this field.

[0011] This invention's three-wing rotary cutter employs a variable cutting radius design (staggered tooth installation and progressively increasing radius), allowing the cutting process to begin with small-radius teeth and gradually transition to larger-radius teeth. This design effectively avoids the cutter tilting or sinking due to insufficient cutting radius, ensuring a smooth cutting process.

[0012] The split-type guide of this invention can absorb the normal vibration energy of the drill pipe through deformation, and its rolling characteristics reduce the wear of the drill pipe and the guide itself caused by the swaying of the drill pipe due to rotary cutting. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the three-wing rotary cutter structure for internal cutting of the drill pipe in the drilling method of the present invention. Figure 2 This is a schematic diagram of the three-wing rotary cutter head structure of the present invention; Figure 3 This is a schematic diagram of the three-wing rotary cutter body structure of the present invention; Figure 4 This is the initial cutting state of the three-wing rotary cutter of the present invention; Figure 5 This is the middle cutting state of the three-wing rotary cutter of the present invention; Figure 6 This is the state in which the three-wing rotary cutter of the present invention has completed cutting; Figure 7 This is a schematic diagram of the split-type guide structure of the present invention; Figure 8This is a schematic diagram of the split guide disk structure of the present invention; Figure 9 This is a schematic diagram showing the relative positions of the three-wing rotary cutter, the split guide, and the drill rod to be cut in this invention. Figure 10 This is a schematic diagram of the kerf shape of the three-bladed rotary cutter cutting drill rod according to the present invention; Figure 11 This is a schematic diagram of the drill pipe rotation deflection of the present invention; Figure 12 This is a schematic diagram of the three-wing rotary cutter cutting method for cutting drill rods according to the present invention.

[0014] Explanation of reference numerals in the attached figures: 1. Cutterhead drill rod connector; 2. Cutterhead; 201. Cutter housing; 202. Wing plate; 3. Three-wing rotary cutter; 301. Cutter teeth; 302. Cutter plate; 303. Cutter body; 304. Cutter shaft; 4. Bolt; 5. Drill rod to be cut; 6. Split guide plate; 601. Guide semicircular plate; 602. Guide wing plate; 603. Guide connecting plate; 604. Guide welding plate; 605. Guide transverse connecting hole; 606. Guide wheel mounting hole; 607. Guide grouting hole; 608. Guide mounting groove; 7. Vertical bolt; 8. Transverse bolt; 9. Guide wheel. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. 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.

[0016] Please see Figure 1 The present invention provides a three-wing rotary cutter structure for internal cutting of drill pipe in deep well drilling method, including cutterhead drill pipe joint 1, cutterhead 2 and three-wing rotary cutter 3; The working principle of the three-wing rotary cutter structure is as follows: a torque (not shown in the diagram) is applied through the ground power head to reach a certain speed, which appears to rotate clockwise when viewed from above the three-wing rotary cutter assembly structure. The speed is generally adjustable from 0 to 300 rpm. Centrifugal force throws the 3-three-wing rotary cutter out to rotate and centrifuge until the 301-cutting teeth installed on the 3-three-wing rotary cutter come into contact and rub against the 5-drill rod being cut. At this point, the cutting operation begins.

[0017] Please see Figure 2The cutter head 2 is connected to the cutter head drill rod joint 1. The cutter head 2 includes upper and lower cutter housings 201 and multiple wing plates 202 connecting the upper and lower cutter housings 201, ensuring that the assembly structure of the three-wing rotary cutter 3 is protected from structural damage during the processes of lowering it to the cutting position, carrying out cutting work, and lifting it to the ground for maintenance. The cutter housings 201 are provided with mounting holes to provide a rotation axis for the three-wing rotary cutter 3.

[0018] There are multiple three-wing rotary cutters 3. Each three-wing rotary cutter 3 is rotatably mounted in the mounting hole of the cutter housing 201 via a cutter shaft 304, and can rotate around the cutter shaft 304 and revolve around the center of the cutter disc 2 under external force. Please see Figure 3 Each three-wing rotary cutter 3 includes a cutter body 303, a cutter plate 302 fixed on the cutter body 303, and a plurality of cutter teeth 301 mounted on the cutter plate 302; Multiple cutting teeth 301 are installed radially staggered on the cutting plate 302 to ensure that the kerf width allows the subsequent cutting plate 302 to enter the drill rod 5 being cut during the later stage of rotary cutting, and to prevent the cutting plate 302 from being clamped due to the kerf width being too narrow during the cutting process, thus preventing the cutting drill rod from being obstructed.

[0019] The blade plate 302 is provided with a plurality of grooves for mounting the blade teeth 301, and the blade teeth 301 are fixed in the grooves by brazing.

[0020] In this embodiment, the blade plate 302 has 10 grooves for mounting the cutting teeth 301. The blade plate 302 and the cutting teeth 301 are connected by brazing. The blade body 303 is thicker than the blade plate 302. On the one hand, it provides support for the stable contact between the cutting teeth 301 and the drill rod 5 being cut during the cutting process. On the other hand, at the same angular velocity, the greater the mass of the three-wing rotary cutter 3, the greater the centrifugal force when it rotates out of the cutter shell 201, which is beneficial to improving the cutting speed. During the process of the three-wing rotary cutter 3 rotating out and retracting the cutter shell 201, the three-wing rotary cutter 3 rotates around the cutter shaft 304 and revolves around the center of the cutter disc 2. During the stable cutting process, the three-wing rotary cutter 3 revolves around the center of the cutter disc 2 and remains relatively stationary with respect to the cutter shaft 304.

[0021] Please see Figure 4-6 The three-wing rotary cutter 3 has different cutting modes at different working stages. In the initial cutting state, the cutting work is undertaken by the cutter teeth 301 with smaller installation radius. At the same cutting speed, the cutting force of the cutter teeth 301 is small. In the intermediate cutting state, the cutting work is undertaken by several middle cutter teeth 301. In the near-complete cutting state, the cutting work is undertaken by the cutter teeth 301 with larger installation radius. At the same cutting speed, the cutting force of the 301 cutter teeth is larger. During the cutting process, since the cutting radius of the three-wing rotary cutter 3 is variable, it can avoid the cutting posture from tilting up or sinking due to insufficient radius, thus increasing the stability of the cutting work.

[0022] The present invention also provides a system for internal cutting of deep well drill pipe, including the above-described three-wing rotary cutter structure; and at least one split-type guide for stably driving the drill pipe of the three-wing rotary cutter structure during the cutting process.

[0023] Please see Figure 7 The main structure of the split guide is composed of two identical 6-split guide discs joined together. The joining method is to connect and weld the adjacent guide connecting plate 603 and guide welding plate 604 with horizontal bolts 8, and the vertical bolts 7 provide a rotation shaft for the guide wheel 9.

[0024] In this embodiment, the split guide is equipped with 6 guide wheels 9. The guide wheels 9 are made of rubber. On the one hand, compared with hard metal, they have a certain deformation when subjected to force to absorb the normal vibration energy of the drill rod. On the other hand, their rolling characteristics can effectively prevent the drill rod from shaking and causing wear on the split guide due to rotary cutting operations.

[0025] Please see Figure 8 The split-type guide plate 6 consists of a guide semicircular plate 601, a guide wing plate 602, a guide connecting plate 603, a guide welding plate 604, a guide transverse connecting hole 605, a guide wheel mounting hole 606, a guide slurry hole 607, and a guide mounting groove 608. The radius of the guide semicircular plate 601 should be slightly smaller than the radius of the drill rod 5 being cut to facilitate the downward movement. The guide wing plate 602 is connected to the upper and lower guide semicircular plates 601 by welding to enhance the vertical and transverse rigidity of the split-type guide plate 6. The guide connecting plate 603 is connected to the upper and lower guide semicircular plates 601 by welding. The guide welding plate 604 increases the welding area of ​​adjacent split-type guide plates 6, and its position should be selected to avoid affecting the mounting bolts of the guide transverse connecting hole 605 and the guide wheel mounting hole 606. The guide slurry hole 607 facilitates other work during cutting, such as circulating mud.

[0026] The purpose of installing the split-type guide is as follows: During drilling operations in deep mud environments, the rotation of the three-wing rotary cutter 3 causes severe oscillation of the cutting pull rod (small-diameter drill rod, not the drill rod being cut 5), leading to a series of engineering problems, such as the inability to meet cutting surface accuracy requirements, increased risk of rod breakage due to friction and impact between the cutting pull rod and the drill rod being cut 5, and increased risk of tooth breakage due to friction and impact between the cutting teeth 301 and the drill rod being cut 5. Therefore, during the lowering process of the three-wing rotary cutter 3, two split-type guides are installed at different positions on the cutting pull rod. The calculation method for their quantity and installation position is as follows: I. Basic parameters of the embodiment:

[0027] II. Calculation of cutter vibration: Step 1: Calculate the fluid excitation force (vibration source) The rotation of the cutter is affected by the viscous resistance of the mud and the inertial centrifugal force. The core calculation is the radial excitation force: 1. Viscous resistance torque ( ) The resistance formula for a rotating disk in a viscous fluid is applied (applicable to scenarios where the cutter diameter is much larger than the drill pipe diameter):

[0028] in: =16.75 rad / s, R=D / 2=0.245 m, =3.42 Pas, substituting this into the equation yields the viscous resistance torque. It is 12.8 Nm.

[0029] 2. Radial excitation force ( ) The resistance torque is converted into radial force (assuming a 0.1mm eccentricity in the drill pipe, a common installation error in the industry): Eccentricity e =0.1mm=1×10 -4 m, the centrifugal force and viscous force coupling during the rotation of the cutter constitute a radial excitation:

[0030] Substitute the data to obtain =93N.

[0031] Step 2: Calculate the vibration response of the drill pipe-cutter system Treating the drill pipe as a "flexible beam with one end fixed (top) and the other end carrying a concentrated mass (cutter)," the vibration amplitude (peak radial displacement) is calculated using Euler-Bernoulli beam theory: 1. Moment of inertia (I) of drill pipe section:

[0032] 2. Peak radial displacement at the cutter (A, i.e., vibration amplitude) = static deformation of the beam + vibration amplification factor (take a resonance safety factor of 2 to avoid resonance conditions):

[0033] Substitute the data: =93N, L =693m, E =2.06×10 11 Pa, I =3.1×10 -6 m 4 Seeking A =16.4mm.

[0034] 3. Vibration magnitude (effective value of acceleration) ) According to the simple harmonic vibration relationship:

[0035] Substituting the data, we obtain: =3.2m / s 2 .

[0036] III. Calculation of Optimal Guiding Position (a) Calculation of the optimal position for a single-guided system The guiding device needs to suppress the "first-order vibration mode of the beam" (the drill pipe is the longest, and the first-order vibration mode contributes more than 90% of the vibration). The core logic is: the guiding device is set at the point where the first-order vibration mode displacement is the largest, so that the suppression effect is optimal.

[0037] Step 1: Determine the node / peak location of the first-order vibration mode of the drill pipe. For a beam that is fixed at one end and has a concentrated mass at the other end, the first-order mode displacement formula is:

[0038] in, β ≈1.875 (first-order mode shape coefficient of fixed-end beam). m rod = ρ steel ×π(d / 2) 2 ×L≈3260kg (total drill pipe mass), m=145kg (cutting tool mass). By calculating the mode shape curve, we obtain: The peak position of the first mode is approximately 0.62L from the top (fixed end), which is approximately 429m deep (0.62×693≈).

[0039] Verification: The radial displacement here accounts for 85% of the displacement at the cutter. Assume that the guide can directly suppress the main vibration source.

[0040] Step 2: Verify the guiding effect (simplified calculation) A guide is installed at 429m (to limit radial displacement). The formula for correcting the vibration amplitude at the cutter is as follows: A 修正 =16.4×(1 (0.85×0.9)≈4.1mm The vibration amplitude is reduced by 75%, meeting the engineering stability requirements (typically ≤5mm is allowed).

[0041] (II) Calculation of optimal location for dual-guided vibration (based on first-order + second-order mode suppression) The core logic of dual-guide is to simultaneously suppress the "first-order vibration mode (main vibration) and second-order vibration mode (secondary vibration) of the drill pipe", and determine the position through the principle of vibration mode superposition to ensure that the vibration suppression efficiency is maximized.

[0042] Core premise: Drill pipe vibration characteristics The drill pipe is a flexible beam with a fixed top and a concentrated mass (cutter) at the bottom. The first two vibration modes contribute more than 95% of the vibration. Key characteristics: First mode shape: overall bending, peak displacement at 0.62L (distance from top, L=693m), node (displacement=0 at 0.22L); Second-order mode: There is one inflection point, with peak displacements at 0.35L and 0.82L, and nodes at 0.12L and 0.65L.

[0043] The dual guides need to avoid all mode shape nodes (which have no suppressive effect) and be aligned with the displacement peak regions of the first two mode shapes respectively.

[0044] Step 1: Determine the first-order mode guide position (guide 1) Continuing with the single-direction logic, priority is given to suppressing the first-order vibration mode that contributes the most: Peak position of first-order mode displacement: 0.62L = 0.62 × 693 ≈ 429m (distance from the top); Verification: This avoids the first-order mode node (at 0.22L≈152m) and can simultaneously weaken the vibration of the second-order mode at 0.82L≈568m (through constraint transmission effect).

[0045] Step 2: Determine the guiding position of the second-order vibration mode (Guiding 2) For the dominant peak value of the second-order mode (0.35L), while avoiding the nodes of the first-order mode (0.22L): Peak position of second-order mode displacement: 0.35L = 0.35 × 693 ≈ 243m (distance from the top); Verification: Here, the first-order mode displacement is 60% of the peak value, which can simultaneously weaken the vibration in the middle and upper part of the first-order mode, forming a "double constraint".

[0046] Step 3: Verification of the dual-guidance effect (simplified calculation) Vibration amplitude correction after dual guidance based on preceding single guidance parameters: 1. Guide 1 (429m): Suppresses 85% of the vibration of the first mode. 2. Guide 2 (243m): Suppresses 70% of the vibration of the first mode. Vibration amplitude at the final cutter: A 双导向 =16.4mm×(1 0.85)×(1 0.7)≈0.7mm. This is far below the safety threshold (5mm).

[0047] IV. Summary of Calculation Results

[0048] Based on the above calculation results, the drill pipe rotation deflection diagram is shown below. Figure 11 As shown.

[0049] Please see Figure 9 The relative positions of the three-wing rotary cutter 3, the split-type guide, and the drill rod 5 being cut are shown in the embodiment. In this embodiment, the three-wing rotary cutter 3 is installed at a position of about 700m, and the split-type guide is installed above the three-wing rotary cutter 3. The number and position of the split-type guide are shown in the drill rod rotation deflection diagram.

[0050] Please see Figure 10 The cutting pattern of the drill rod is that of a three-wing rotary cutter. Through on-site investigation, the cut surface after the cutting is completed shows a cutting pattern that is wider on the inside and narrower on the outside when viewed from the side. It can be seen that the drill rod 5 is successfully penetrated by the mechanical structure of the three-wing rotary cutter 3 and the split guide stabilizer.

[0051] The present invention also provides a method for deep well drill pipe internal cutting using the system described above, comprising the following steps: S1: Design and manufacture the cutting cutter head, and conduct indoor tests in the laboratory. By observing the cutting effect, adjust the design size of the three-wing rotary cutter and the metal materials used to verify the cutting effectiveness of the three-wing rotary cutter on the drill rod 5 being cut.

[0052] S2: Prepare the work site, check the conventional electrical equipment and prepare backup power.

[0053] S3: Before cutting operations, perform maintenance and repairs on the TSJ2000 drilling rig's rotary table, gearbox, coupling, clutch, and brake.

[0054] S4: Use a self-made three-winged alloy blade (material: YS2T / 325 alloy, cutting thickness 14mm) for on-site installation.

[0055] S5: Before lowering the rotary cutter, use a copper core to connect the upper and lower pans to block the cutter and prevent the blade from protruding and scraping the drill rod during the lowering process. Then remove the turntable, lower the rotary cutter, and lock it with a wire rope. Then install the turntable, measure the drill rod size, and lower the drill rod. The first drill rod is a 6m long counterweight drill rod. While lowering the drill rod, observe whether the drill rod is bent after hoisting it. After tightening the threads of the last two drill rods, weld the tube segments symmetrically at the joint of the two drill rods to prevent the threads from coming loose. Install two sets of guide devices at different positions.

[0056] S6: When cutting, start with low speed and observe the system stability and coaxiality. After the cutting is stable for 2 hours without any problems, gradually increase to the maximum speed. If the drill rod shakes violently or the current is unstable during the speed increase, the speed should be reduced in time.

[0057] S7: For normal tool retraction, use low-speed forward rotation for 2-3 minutes, followed by jogging to lift.

[0058] S8: The drilling rod lifting operation should be carried out at a constant speed. Observe the changes in the crane scale display during the lifting process, especially when passing two fishing devices, the lifting speed should be slow.

[0059] S9: Check the cutting depth of the drill pipe and the wear condition of the three-wing rotary cutter: If the Φ610 drill pipe suddenly bounces up or the jack pressure decreases during the cutting process, determine the cutting depth by combining the cutting time and the wear position of the three-wing rotary cutter. If it is not completely cut through, return to S4 and repeat S4-S9 until the drill pipe is completely cut off.

[0060] S10: After cutting is completed, clean up the site and carry out subsequent operations.

[0061] It should be noted that if the embodiments of the present invention involve directional indicators such as up, down, left, right, front, back, etc., the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture as shown in the attached figure. If the specific posture changes, the directional indicators will also change accordingly.

[0062] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied. Furthermore, "multiple" refers to two or more. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A three-wing rotary cutter structure for internal cutting of drill pipe in deep well drilling, characterized in that: include; Cutterhead drill rod connector (1); The cutter head (2) is connected to the cutter head drill rod joint (1). The cutter head (2) includes upper and lower cutter shells (201) and multiple wing plates (202) connecting the upper and lower cutter shells (201). The cutter shells (201) are provided with mounting holes. There are multiple three-wing rotary cutters (3). Each three-wing rotary cutter (3) is rotatably mounted in the mounting hole of the cutter shell (201) via a cutter shaft (304) and can rotate around the cutter shaft (304) and revolve around the center of the cutter disc (2) under external force. Each three-wing rotary cutter (3) includes a cutter body (303), a cutter plate (302) fixed on the cutter body (303), and multiple cutter teeth (301) mounted on the cutter plate (302).

2. The three-wing rotary cutter structure for internal cutting of drill pipe in deep well drilling method according to claim 1, characterized in that: The plurality of cutting teeth (301) are installed radially staggered on the blade plate (302).

3. The three-wing rotary cutter structure for internal cutting of drill pipe in deep well drilling method according to claim 1 or 2, characterized in that: The material of the cutting teeth (301) is YS2T / 325 alloy.

4. The three-wing rotary cutter structure for internal cutting of drill pipe in deep well drilling method according to claim 1, characterized in that: The blade plate (302) is provided with a plurality of grooves for mounting the blade teeth (301), and the blade teeth (301) are fixed in the grooves by brazing.

5. A system for internal cutting of deep well drill pipe, characterized in that: include; The three-wing rotary cutter structure according to any one of claims 1-4; At least one split-type guide is used to stably drive the drill rod of the three-wing rotary cutter structure during cutting.

6. The system for internal cutting of deep well drill pipe according to claim 5, characterized in that: The split guide includes two split guide discs (6) that can be joined together to form a whole. Each split guide disc (6) includes a guide semicircular plate (601), a guide wing plate (602) connecting the guide semicircular plate (601), and a guide wheel mounting hole (606) provided on the guide semicircular plate (601). The split guide also includes a guide wheel (9) mounted in the guide wheel mounting hole (606) by a vertical bolt (7), and a transverse bolt (8) for connecting the two split guide discs (6).

7. The system for internal cutting of deep well drill pipe according to claim 5, characterized in that: The split guide plate (6) also includes a guide slurry hole (607) provided on the guide semicircular plate (601).

8. The system for internal cutting of deep well drill pipe according to claim 5, characterized in that: The guide wheel (9) is made of rubber.

9. A method for deep well drill pipe internal cutting using the system as described in any one of claims 5-8, characterized in that: Includes the following steps; S1: Design and manufacture a cutting disc containing a three-wing rotary cutter (3), and conduct indoor cutting tests to verify and optimize the design; S2: Prepare the on-site work area and related equipment; S3: Perform maintenance and repair on relevant components of the drilling rig; S4: Install the three-wing rotary cutter (3); S5: Lower the assembled three-wing rotary cutter structure and at least one split-type guide into the predetermined cutting position inside the drill pipe, wherein the split-type guide is installed at a specific position driving the drill pipe; S6: Start the cutting operation, initially using a low speed, and gradually increase to the working speed after the system stabilizes; S7: After cutting for a period of time, retract the tool by rotating it forward at a low speed and using a jogging motion. S8: Lift the drill pipe at a constant speed and monitor the lifting process; S9: Check the cutting depth and tool wear. If the cut is not completely made, repeat steps S4 to S9. S10: After cutting, clean up the site.

10. The method for deep well drill pipe internal cutting according to claim 9, characterized in that: In step S5, the installation position of the split guide is determined by calculation through the following steps; Obtain basic parameters including mud properties, drill pipe parameters, cutter parameters, and material properties; Based on the aforementioned basic parameters, the fluid excitation force generated by the three-wing rotary cutter (3) when rotating in the mud environment is calculated; The drill pipe is simplified into a beam model with a fixed top and a concentrated mass at the bottom, and the vibration amplitude at the cutter is calculated when there is no guide. Based on the first and second mode characteristics of the drill pipe, determine the installation position of the guide that can effectively suppress the main vibration.

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