PDC drill bit capable of actively adapting to lithologic change

Abstract

The utility model discloses a polycrystalline diamond compact (PDC) drill bit capable of actively adapting to lithologic changes, which comprises a drill bit base body, a plurality of self-adaptive teeth and a plurality of fixed teeth, and the plurality of self-adaptive teeth and the plurality of fixed teeth are sequentially distributed at the upper end of the drill bit base body in a staggered mode. The upper end of the drill bit base body is provided with a groove key structure used for assembling the self-adaptive tooth and a spring hole used for assembling the spring plug and the elastic element, the self-adaptive tooth comprises a self-adaptive matrix, a first PDC tooth, a first bolt, a second bolt, a limiting block, the spring plug and the elastic element, and the self-adaptive matrix is connected to the upper end of the drill bit base body in a limiting mode through the groove key structure; the first PDC teeth are fixedly arranged at the upper end of the self-adaptive tire body, the first bolt is in threaded connection with the upper end of the self-adaptive tire body, the elastic element and the spring plug are arranged in the spring hole, and the elastic element is located below the spring plug and makes contact with the spring plug; the lower end of the first bolt abuts against the upper end of the spring plug, the limiting block is arranged on the self-adaptive tire body through a second bolt, and second PDC teeth are fixedly arranged on the upper portions of the fixing teeth.

Description

Technical Field

[0001] The utility model relates to an adaptive drill bit in the field of drilling and well - drilling, and particularly to a PDC drill bit that can actively adapt to lithology changes. Background Technique

[0002] The polycrystalline diamond compact bit (abbreviation: PDC bit) originated in the 1970s. It is an advanced drilling tool that combines the hardness of diamond and the toughness of cemented carbide matrix, and is particularly suitable for fields such as geological exploration and oil and gas exploitation. However, one drilling angle of the PDC bit cutting teeth is only applicable to rocks with one mechanical property. When drilling in a formation with large rock hardness changes, the drilling efficiency of the bit decreases significantly, and the service life will also be greatly reduced. In addition, the back rake angle of the PDC bit cutting teeth has a great influence on the drilling speed and the bit life. The smaller the angle, the higher the efficiency of the PDC teeth. When cutting soft formations, the smaller the angle, the more conducive to the exertion of the mechanical drilling speed. At the same time, the soft rock has low hardness and limited damage to the cutting teeth. When drilling hard formations, an appropriate increase in the back rake angle is beneficial to reducing the damage caused by rock impact fragments and increasing the bit life.

[0003] Some existing patents have made improvement studies on the adaptability of drill bits. For example, the utility model patent named "PDC bit with alternating front rake angle" (patent number: 202411184163.X) improves the adaptability of the bit to complex formations through PDC teeth with alternating front rake angles arranged along the radius direction of the bit. Its rock intrusion ability is higher than that of conventional PDC bits. The front rake angles of the PDC teeth set on the bit change alternately, forming an effective restricted penetration structure, and the buffering ability is enhanced. However, the adaptation range of this bit to the formation is still relatively narrow, and it is difficult to cope with complex and changeable formation environments. Another example is the utility model patent named "A bionic adaptive PDC bit" (patent number: 201510428061.2), which imitates the tiger's claw bones and designs the structure of the bionic adaptive PDC bit according to the self - adaptive characteristics of its claws. By using the biological claw toes to achieve self - protection through joint activities, when drilling in complex formations, under the action of formation impact force, it can adaptively change the cutting angle of the cutting teeth, effectively reducing and avoiding the impact force damage of formation changes to the cutting teeth, and improving the bit life and drilling efficiency. However, the adaptive elements of this bit are prone to failure due to large stresses, and the entire bit is composed of adaptive teeth, which is greatly affected by the drilling pressure. Especially when overcoming hard - soft interlayers, it is extremely easy to cause the bottom hole to be uneven, resulting in bit bounce, which affects the quality of drilling coring or well - drilling. Therefore, it is necessary to carry out innovative research to develop a PDC bit that can actively adapt to lithology changes, has reasonable stress and a long service life. Summary of the Invention

[0004] The object of the present utility model is to solve the problems encountered by the above-mentioned bionic adaptive PDC bit, such as unreasonable force on the adaptive element, short service life, and severe bit bounce when drilling through hard and soft interbedded formations, and to provide a PDC bit that can actively adapt to lithological changes.

[0005] A PDC bit that can actively adapt to lithological changes includes a bit matrix, a number of adaptive teeth, and a number of fixed teeth. The number of adaptive teeth and the number of fixed teeth are alternately distributed on the upper end of the bit matrix in sequence;

[0006] On the upper end of the bit matrix, there are provided a keyway structure for assembling the adaptive teeth and a spring hole for assembling the spring plug and the elastic element;

[0007] The adaptive tooth includes an adaptive matrix, a first PDC tooth, a first bolt, a second bolt, a limit block, a spring plug, and an elastic element;

[0008] The adaptive matrix is limited and connected to the upper end of the bit matrix through the keyway structure. The first PDC tooth is fixedly arranged on the upper end of the adaptive matrix. The first bolt is threadedly connected to the upper end of the adaptive matrix. The elastic element and the spring plug are arranged in the spring hole. The elastic element is located below the spring plug and contacts it; the lower end of the first bolt abuts against the upper end of the spring plug. The limit block is arranged on the adaptive matrix through the second bolt;

[0009] On the upper part of the fixed tooth, a second PDC tooth is fixedly arranged.

[0010] Preferably, when cutting rock, the back rake angle α of the adaptive tooth varies within the range of 0° to 18°, and the initial back rake angle is 0° to 10°; the back rake angle β of the fixed tooth is fixedly set to 20°.

[0011] Preferably, the adaptive teeth and the fixed teeth are polycrystalline diamond compacts, and the elastic element is a spring. By compressing the spring, conditions are created for the displacement of the spring plug and the adaptive matrix, thereby changing the back rake angle of the adaptive tooth.

[0012] Preferably, the adaptive teeth are arranged on the bit matrix through the keyway structure. The keyway structure has a groove that fits the dimensions of the adaptive matrix and the limit block. After the adaptive teeth are assembled onto the bit matrix, the radial displacement of the adaptive teeth is restricted by the limit block, and the limit block is fixed by the second bolt.

[0013] Preferably, when drilling a rock of a certain hardness under a certain bit weight, the reaction force on the adaptive tooth remains unchanged. According to Hooke's law, before drilling, the cooperation between the first bolt and the elastic element and the parameters of the elastic element are adjusted so that the elastic force of the elastic element is balanced with the reaction force on the adaptive tooth, so that the cutting angle of the adaptive tooth remains the best angle for cutting the rock with this mechanical property during drilling.

[0014] The beneficial effects of the present utility model:

[0015] The structure of the utility model is ingenious, easy to manufacture, convenient to assemble and disassemble, stable and reliable. The adaptive teeth and fixed teeth are used timely according to the rock and formation environment to reduce the impact damage of the formation change on the cutting teeth, effectively improve the reliability of the adaptive teeth of the drill bit, the service life of the drill bit and the drilling efficiency, reduce the number of times of replacing the drill bit, reduce the auxiliary time of tripping in and out, and reduce the drilling cycle. In addition, the elastic element can be a spring, which is convenient to obtain materials, low in cost and good in effect. Springs with different parameters can be selected according to the formation environment and rock characteristics of the drilled formation, so that the cutting angle of the adaptive teeth can maintain the best angle for cutting a kind of mechanical property rock during drilling. Description of the Drawings

[0016] Figure 1 is a three-dimensional schematic diagram of the utility model;

[0017] Figure 2 is a schematic diagram of the rake angle of the adaptive teeth;

[0018] Figure 3 is a schematic diagram of the rake angle of the fixed teeth;

[0019] Figure 4 is a schematic diagram of the elastic element, spring plug and nut;

[0020] Figure 5 is a schematic diagram of the state of the cutting teeth when cutting soft rock;

[0021] Figure 6 is a schematic diagram of the state of the cutting teeth when cutting hard rock;

[0022] Figure 7 is a schematic diagram of the limiting principle of the limiting block;

[0023] Figure 8 is a schematic diagram of the key groove structure and spring hole of the drill bit matrix. Detailed Embodiment

[0024] Referring to the drawings, a PDC drill bit capable of actively adapting to lithology changes includes a drill bit matrix 1, a plurality of adaptive teeth 2 and a plurality of fixed teeth 3. The plurality of adaptive teeth 2 and the plurality of fixed teeth 3 are alternately distributed at the upper end of the drill bit matrix 1 in sequence;

[0025] A key groove structure 11 for assembling the adaptive teeth 2 and a spring hole 12 for assembling the spring plug 26 and the elastic element 27 are provided at the upper end of the drill bit matrix 1;

[0026] The adaptive tooth 2 includes an adaptive matrix 21, a first PDC tooth 22, a first bolt 23, a second bolt 24, a limiting block 25, a spring plug 26 and an elastic element 27;

[0027] The adaptive matrix body 21 is connected and limited to the upper end of the drill bit matrix body 1 through a key groove structure 11. The first PDC tooth 22 is fixedly arranged at the upper end of the adaptive matrix body 21. The first bolt 23 is threadedly connected to the upper end of the adaptive matrix body 21. An elastic element 27 and a spring plug 26 are arranged in a spring hole 12. The elastic element 27 is located below the spring plug 26 and contacts with it; the lower end of the first bolt 23 abuts against the upper end of the spring plug 26. The limiting block 25 is arranged on the adaptive matrix body 21 through a second bolt 24;

[0028] The upper part of the fixed tooth 3 is fixedly provided with a second PDC tooth 31.

[0029] Furthermore, when cutting rock, the back rake angle α of the adaptive tooth 2 varies within the range of 0° to 18°, and the initial back rake angle is 0° to 10°; the back rake angle β of the fixed tooth 3 is fixedly set to 20°.

[0030] Furthermore, the material of the drill bit matrix body 1 is No. 45 steel. The adaptive tooth 2 and the fixed tooth 3 are both polycrystalline diamond compact or other superhard materials. The elastic element 27 is a spring with relatively high strength. By compressing the spring, conditions are created for the displacement of the spring plug 26 and the adaptive matrix body 21, thereby changing the back rake angle of the adaptive tooth 2.

[0031] Furthermore, the adaptive tooth 2 is arranged on the drill bit matrix body 1 through the key groove structure 11. The key groove structure 11 has a groove that fits the sizes of the adaptive matrix body 21 and the limiting block 25. After the adaptive tooth 2 is assembled onto the drill bit matrix body 1, the radial displacement of the adaptive tooth 2 is restricted by the limiting block 25, and the limiting block 25 is fixed by the second bolt 24. The width of the limiting block 25 fits the groove reserved by the key groove structure 11 to prevent the radial vibration or detachment of the adaptive tooth 2.

[0032] Furthermore, when drilling a rock of a certain hardness under a certain drilling pressure, the reaction force received by the adaptive tooth 2 remains unchanged. According to Hooke's law, the cooperation between the first bolt 23 and the elastic element 27 and the parameters of the elastic element 27 can be adjusted before lowering the drill to balance the elastic force of the elastic element 27 with the reaction force received by the adaptive tooth 2, so that the cutting angle of the adaptive tooth 2 can maintain the best angle for cutting the rock with this mechanical property during drilling.

[0033] The working principle and process of the present utility model:

[0034] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8As shown, when the elastic element 27 is not under force, it does not deform, and this is the initial backward inclination state of the self-adaptive tooth 2. During drilling, when drilling through a formation with large variations in hardness, as the formation changes, the drill bit is subjected to the reaction force of the rock. The deformation of the elastic element 27 in the self-adaptive tooth 2 drives the rotation of the self-adaptive tooth 2, thereby changing the cutting angle of the self-adaptive tooth 2. When drilling through a soft rock formation, the angle change of the self-adaptive tooth 2 is small and close to vertical. The self-adaptive tooth 2 undertakes most of the rock-breaking drilling tasks, and the fixed tooth 3 assists in drilling to increase the drilling speed. When drilling through a hard rock formation, the reaction force of the rock increases, and the backward inclination angle of the self-adaptive tooth 2 increases, being nearly the same as that of the fixed tooth 3. At this time, the two work together to increase the overall strength of the cutting teeth and improve the service life of the self-adaptive tooth 2 and the drill bit.

[0035] In addition, when drilling a rock of a certain hardness under a certain drilling pressure, the reaction force on the self-adaptive tooth 2 remains unchanged. According to Hooke's law, the cooperation between the first bolt 23 and the elastic element 27 and the parameters of the elastic element can be adjusted before lowering the drill to balance the elastic force of the elastic element 27 with the reaction force on the self-adaptive tooth 2, so that the cutting angle of the self-adaptive tooth remains at the optimal angle for cutting a rock with this mechanical property during drilling.

Claims

1. A PDC bit capable of actively adapting to lithology changes, characterized in that: It includes a drill bit matrix (1), several adaptive teeth (2) and several fixed teeth (3), and the several adaptive teeth (2) and the several fixed teeth (3) are alternately distributed at the upper end of the drill bit matrix (1) in sequence; At the upper end of the drill bit matrix (1), there is a keyway structure (11) for assembling the adaptive teeth (2) and a spring hole (12) for assembling a spring plug (26) and an elastic element (27); The adaptive tooth (2) includes an adaptive matrix (21), a first PDC tooth (22), a first bolt (23), a second bolt (24), a limit block (25), a spring plug (26) and an elastic element (27); The adaptive matrix (21) is limited and connected to the upper end of the drill bit matrix (1) through the keyway structure (11), the first PDC tooth (22) is fixedly arranged at the upper end of the adaptive matrix (21), the first bolt (23) is threadedly connected to the upper end of the adaptive matrix (21), the elastic element (27) and the spring plug (26) are arranged in the spring hole (12), the elastic element (27) is located below the spring plug (26) and contacts with it; the lower end of the first bolt (23) abuts against the upper end of the spring plug (26), and the limit block (25) is arranged on the adaptive matrix (21) through the second bolt (24); At the upper part of the fixed tooth (3), a second PDC tooth (31) is fixedly arranged.

2. The PDC bit capable of actively adapting to lithology changes according to claim 1, characterized in that: When cutting rock, the rake angle α of the adaptive tooth (2) varies within the range of 0° to 18°, and the initial rake angle is 0° to 10°; the rake angle β of the fixed tooth (3) is fixedly set to 20°.

3. The PDC bit capable of actively adapting to lithology changes according to claim 1, characterized in that: The adaptive tooth (2) and the fixed tooth (3) are polycrystalline diamond compacts, and the elastic element (27) is a spring. The compression of the spring creates conditions for the displacement of the spring plug (26) and the adaptive matrix (21), thereby changing the rake angle of the adaptive tooth (2).

4. A PDC bit capable of actively adapting to lithology changes according to claim 1, characterized in that: The adaptive tooth (2) is arranged on the drill bit matrix (1) through the keyway structure (11). The keyway structure (11) has a groove that fits the dimensions of the adaptive matrix (21) and the limit block (25). After the adaptive tooth (2) is assembled onto the drill bit matrix (1), the radial displacement of the adaptive tooth (2) is restricted by the limit block (25), and the limit block (25) is fixed by the second bolt (24).

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