PDC drill bit capable of actively adapting to lithologic change

Abstract

The PDC drill bit capable of actively adapting to the lithology change comprises a drill bit base body, a plurality of self-adaptive teeth and a plurality of fixed teeth, and the self-adaptive teeth and the 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 invention relates to an adaptive drill bit in the field of drilling and well drilling, and in particular to a PDC drill bit that can actively adapt to changes in lithology. Background Art

[0002] Polycrystalline diamond composite drill bits (PDC drill bits for short) originated in the 1970s. They are an advanced drilling tool that combines the hardness of diamond with the toughness of cemented carbide matrix. They are particularly suitable for geological exploration, oil and gas extraction and other fields. However, one drilling angle of the PDC drill bit cutting teeth is only suitable for rocks with one mechanical property. When drilling into formations with large changes in rock hardness, the drilling efficiency of the drill bit is significantly reduced and its life is greatly reduced. In addition, the rake angle of the PDC drill bit cutting teeth has a great influence on the drilling speed and drill 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 it is to the mechanical drilling speed. At the same time, the hardness of soft rocks is low, and the damage to the cutting teeth is limited. When drilling into hard formations, an appropriate increase in the rake angle is conducive to reducing the damage caused by rock impact fragments and increasing the life of the drill bit.

[0003] Some patents have been studied to improve the adaptability of drill bits, such as the invention patent named "PDC drill bit with alternating rake angle" (patent number: 202411184163.X), which improves the adaptability of the drill bit to complex formations by using PDC teeth with staggered rake angles arranged along the radial direction of the drill bit. Its rock invasion ability is higher than that of conventional PDC drill bits. The staggered rake angles of the PDC teeth set on the drill bit form an effective limited entry structure, and the buffering capacity is enhanced. However, the adaptability range of the drill bit to the formation is still relatively narrow, and it is difficult to cope with complex and changing formation environments. For example, the invention patent named "A Bionic Adaptive PDC Drill Bit" (patent number: 201510428061.2) uses a bionic tiger claw skeleton. The bionic adaptive PDC drill bit structure is designed based on the adaptive characteristics of its claws. The biological claws are used to achieve self-protection through joint activities. When drilling in complex formations, the cutting angle of the cutting teeth can be adaptively changed under the impact of the formation. It can effectively slow down and avoid the impact damage to the cutting teeth caused by formation changes, and improve the life and drilling efficiency of the drill bit. However, the adaptive elements of the drill bit are prone to failure due to the large stress, and the entire drill bit is adaptive teeth, which are greatly affected by drilling pressure. Especially when overcoming soft and hard interlayers, it is very easy to cause uneven bottom of the well and cause drilling jump phenomenon, affecting the quality of drilling coring or drilling quality. For this reason, it is necessary to carry out innovative research to invent a PDC drill bit with reasonable force, long life, and active adaptation to lithology changes. Summary of the invention

[0004] The purpose of the present invention is to solve the problems encountered by the above-mentioned bionic adaptive PDC drill bit, such as unreasonable stress on the adaptive element, short service life and serious drill jumping when drilling soft and hard interlayer formations, and to provide a PDC drill bit that can actively adapt to changes in lithology.

[0005] A PDC drill bit capable of actively adapting to rock property changes comprises a drill bit base, a plurality of adaptive teeth and a plurality of fixed teeth, wherein the plurality of adaptive teeth and the plurality of fixed teeth are alternately distributed on the upper end of the drill bit base; The upper end of the drill bit base body is provided with a slot key structure for assembling the adaptive teeth and a spring hole for assembling the spring plug and the elastic element; The adaptive tooth comprises an adaptive carcass, a first PDC tooth, a first bolt, a second bolt, a limit block, a spring plug and an elastic element; The adaptive carcass is limitedly connected to the upper end of the drill bit base body through a slot key structure, the first PDC tooth is fixedly arranged on the upper end of the adaptive carcass, the first bolt is threadedly connected to the upper end of the adaptive carcass, the elastic element and the spring plug are arranged in the spring hole, the elastic element is located below the spring plug and contacts the spring plug; the lower end of the first bolt abuts against the upper end of the spring plug, and the limit block is arranged on the adaptive carcass through the second bolt; A second PDC tooth is fixedly arranged on the upper part of the fixed tooth.

[0006] Preferably, when cutting rock, the adaptive tooth back rake angle α varies in the range of 0° to 18°, and the initial back rake angle is 0° to 10°; the fixed tooth back rake angle β is fixedly set to 20°.

[0007] Preferably, the adaptive teeth and the fixed teeth are polycrystalline diamond composite sheets, and the elastic element is a spring. The compression of the spring creates conditions for the displacement of the spring plug and the adaptive matrix, thereby changing the backward tilt angle of the adaptive teeth.

[0008] Preferably, the adaptive teeth are arranged on the drill bit base through a slot key structure, and the slot key structure has a slot that matches the size of the adaptive matrix and the limit block. After the adaptive teeth are assembled on the drill bit base, the radial displacement of the adaptive teeth is limited by the limit block, and the limit block is fixed by a second bolt.

[0009] Preferably, when drilling a rock of a certain hardness under a certain drilling pressure, the reaction force received by the adaptive tooth remains unchanged, and according to Hooke's law, the fit between the first bolt and the elastic element and the parameters of the elastic element are adjusted before drilling, so that the elastic force of the elastic element and the reaction force received by the adaptive tooth are balanced, so that the cutting angle of the adaptive tooth maintains the optimal angle for cutting the rock with the mechanical properties during drilling.

[0010] Beneficial effects of the present invention: The present invention has an ingenious structure, is easy to manufacture, convenient to load and unload, and is stable and reliable. The adaptive teeth and fixed teeth are used in a timely manner according to the rock and stratum environment to reduce the impact damage of stratum changes on the cutting teeth, effectively improving the reliability of the drill bit's adaptive teeth, the drill bit's life and the drilling efficiency, reducing the number of drill bit replacements, reducing the auxiliary time for drilling and drilling, and shortening the drilling cycle. In addition, the elastic element can be made of a spring, which is easy to obtain, low in cost, and has a good effect. Springs with different parameters can be selected according to the stratum environment and rock characteristics to be drilled, so that the adaptive tooth cutting angle maintains an optimal angle for cutting a rock with a certain mechanical property during drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a three-dimensional schematic diagram of the present invention; Figure 2 Schematic diagram of the back tilt angle of the adaptive tooth; Figure 3 Schematic diagram of the back tilt angle of the fixed tooth; Figure 4 It is a schematic diagram of the elastic element, the spring plug and the nut; Figure 5 It is a schematic diagram of the state of the cutting teeth when cutting soft rock; Figure 6 It is a schematic diagram of the state of the cutting teeth when cutting hard rock; Figure 7 It is a schematic diagram of the limiting principle of the limiting block; Figure 8 Schematic diagram of the drill bit base slot key structure and spring hole. DETAILED DESCRIPTION

[0012] Please refer to the attached drawings, a PDC drill bit that can actively adapt to rock property changes includes a drill bit base 1, a plurality of adaptive teeth 2 and a plurality of fixed teeth 3, wherein the plurality of adaptive teeth 2 and the plurality of fixed teeth 3 are alternately distributed on the upper end of the drill bit base 1; The upper end of the drill bit base body 1 is provided with a slot key structure 11 for assembling the adaptive tooth 2 and a spring hole 12 for assembling the spring plug 26 and the elastic element 27; The adaptive tooth 2 comprises an adaptive carcass 21, a first PDC tooth 22, a first bolt 23, a second bolt 24, a stopper 25, a spring plug 26 and an elastic element 27; The adaptive carcass 21 is limitedly connected to the upper end of the drill bit base 1 through the slot key structure 11, the first PDC tooth 22 is fixedly arranged on the upper end of the adaptive carcass 21, the first bolt 23 is threadedly connected to the upper end of the adaptive carcass 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 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 carcass 21 through the second bolt 24; A second PDC tooth 31 is fixedly disposed on the upper portion of the fixed tooth 3 .

[0013] Furthermore, when cutting rock, the back rake angle α of the adaptive tooth 2 varies in 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°.

[0014] Furthermore, the drill bit base 1 is made of 45 steel, the adaptive teeth 2 and the fixed teeth 3 are both polycrystalline diamond composite sheets or other superhard materials, and the elastic element 27 is a high-strength spring. The compression of the spring creates conditions for the displacement of the spring plug 26 and the adaptive matrix 21, thereby changing the backward tilt angle of the adaptive tooth 2.

[0015] Furthermore, the adaptive tooth 2 is arranged on the drill bit base 1 through the slot key structure 11, and the slot key structure 11 has a slot that matches the size of the adaptive matrix 21 and the limit block 25. After the adaptive tooth 2 is assembled on the drill bit base 1, the radial displacement of the adaptive tooth 2 is limited by the limit block 25, and the limit block 25 is fixed by the second bolt 24. The width of the limit block 25 matches the slot reserved by the slot key structure 11 to prevent the adaptive tooth 2 from radial vibration or falling off.

[0016] 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 fit between the first bolt 23 and the elastic element 27 and the parameters of the elastic element 27 can be adjusted before drilling, so that the elastic force of the elastic element 27 and the reaction force received by the adaptive tooth 2 are balanced, so that the cutting angle of the adaptive tooth 2 can maintain the optimal angle for cutting the rock with this kind of mechanical properties during drilling.

[0017] Working principle and process of the present invention: See also Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, the elastic element 27 does not deform when not under force, and this is the initial rake angle state of the adaptive tooth 2. During the drilling process, when drilling into a stratum with large changes in hardness and softness, the drill bit is affected by the rock reaction force as the stratum changes, and the adaptive tooth 2 is driven to rotate by the deformation of the elastic element 27 in the adaptive tooth 2, thereby changing the cutting angle of the adaptive tooth 2. When drilling into soft rock formations, the angle of the adaptive tooth 2 changes less and is close to vertical. The adaptive tooth 2 undertakes most of the rock crushing drilling tasks, and the fixed tooth 3 assists in drilling to increase the drilling speed; when drilling into hard rock formations, the rock reaction force increases, and the rake angle of the adaptive tooth 2 increases, which is almost the same as the rake angle of the fixed tooth 3. At this time, the two work together to increase the overall cutting tooth strength and improve the life of the adaptive tooth 2 and the drill bit.

[0018] In addition, when drilling a rock of a certain hardness under a certain drilling pressure, the reaction force on the adaptive tooth 2 remains unchanged. According to Hooke's law, the fit between the first bolt 23 and the elastic element 27 and the parameters of the elastic element can be adjusted before drilling, so that the elastic force of the elastic element 27 and the reaction force on the adaptive tooth 2 are balanced, so that the cutting angle of the adaptive tooth can maintain the optimal angle for cutting the rock with the mechanical properties during drilling.

Claims

1. A PDC drill bit that can actively adapt to changes in lithology, characterized by: The drill bit comprises a drill base body (1), a plurality of adaptive teeth (2) and a plurality of fixed teeth (3), wherein the plurality of adaptive teeth (2) and the plurality of fixed teeth (3) are alternately distributed on the upper end of the drill base body (1); The upper end of the drill bit base (1) is provided with a slot key structure (11) for assembling the adaptive tooth (2) and a spring hole (12) for assembling the spring plug (26) and the elastic element (27); The adaptive tooth (2) comprises an adaptive carcass (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 carcass (21) is positionally connected to the upper end of the drill bit base (1) via a slot key structure (11); the first PDC tooth (22) is fixedly arranged on the upper end of the adaptive carcass (21); the first bolt (23) is threadedly connected to the upper end of the adaptive carcass (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 the spring plug (26); 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 carcass (21) via a second bolt (24); A second PDC tooth (31) is fixedly arranged on the upper part of the fixed tooth (3).

2. A PDC drill bit capable of actively adapting to lithology changes according to claim 1, characterized in that: 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°.

3. A PDC drill bit capable of actively adapting to lithology changes according to claim 1, characterized in that: The adaptive teeth (2) and the fixed teeth (3) are polycrystalline diamond composite sheets, 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 backward tilt angle of the adaptive teeth (2).

4. A PDC drill 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 base (1) via a slot key structure (11), the slot key structure (11) has a slot matching the size of the adaptive matrix (21) and the limit block (25), and after the adaptive tooth (2) is assembled on the drill bit base (1), the limit block (25) limits the radial displacement of the adaptive tooth (2), and the limit block (25) is fixed by a second bolt (24).

5. A PDC drill bit capable of actively adapting to lithology changes according to claim 1, characterized in that: When drilling a rock of a certain hardness under a certain drilling pressure, the reaction force on the adaptive tooth (2) remains unchanged. According to Hooke's law, before drilling, the matching between the first bolt (23) and the elastic element (27) and the parameters of the elastic element (27) are adjusted so that the elastic force of the elastic element (27) and the reaction force on the adaptive tooth (2) are balanced, so that the cutting angle of the adaptive tooth (2) maintains an optimal angle for cutting the rock with the mechanical properties during drilling.

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