A PDC drill bit

Abstract

The present invention proposes a PDC drill bit, which relates to the technical field of oilfield drilling engineering. The PDC drill bit includes a drill bit body, a water injection cavity is provided in the drill bit body, and a plurality of water outlets are provided at the end of the drill bit body, each water outlet is respectively connected to the water injection cavity, and each water outlet is respectively provided with a nozzle, each nozzle is tubular and has an axially through water outlet cavity, one end of each nozzle is a water outlet end, and the other end of each nozzle is a mounting end, each mounting end is penetrated into the corresponding water outlet and rotatably cooperates with the inner wall of the water outlet, each water outlet end protrudes outwardly from the end face of the drill bit body, and at least one notch connected to the water outlet cavity is provided on the side wall of each water outlet end. The PDC drill bit proposed by the present invention can adapt to the deep high temperature and high pressure environment, and ensure the life of the drill bit while improving the mechanical drilling speed.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield drilling engineering, in particular to a PDC drill bit. Background Art

[0002] In the process of oil and gas exploration, it is found that more and more proven oil and gas resources are buried in deep formations. Therefore, deep wells and ultra-deep wells have become the trend of oil and gas resource exploration and development, and PDC drill bits are currently the most widely used drill bits in deep well drilling. However, when using PDC drill bits in deep wells and ultra-deep wells, due to the deep burial of oil and gas reservoirs, the mechanical drilling speed and service life of PDC drill bits in deep high temperature and high pressure environments are limited, affecting the entire drilling process and the final economic benefits.

[0003] In view of the above situation, many drill bit designers have adopted the approach of lengthening the nozzle in order to improve the rock breaking efficiency and mechanical drilling speed in deep formations. However, this approach still has the following three shortcomings in practice:

[0004] 1. The extended nozzle is not strong and is easy to break during deep well drilling. The broken nozzle is difficult to carry out of the bottom of the well, which aggravates the wear of the drill bit and makes it difficult for the drill bit to continue drilling.

[0005] 2. Extending the nozzle in the direction facing the formation helps to reduce rock strength, extend micro-cracks, and improve rock breaking efficiency. However, there is no diversion of drilling fluid to the blade and cutting teeth, resulting in the cutting teeth not being able to cool in time and greatly reducing their service life.

[0006] 3. The extended nozzle has a limited range of action on the bottom of the well, and cannot remove the carried cuttings in time, which can easily cause complex downhole working conditions such as mud packing on the drill bit and repeated crushing of cuttings. In serious cases, the drill has to be started early.

[0007] In view of this, the inventor has designed a PDC drill bit based on many years of production and design experience in this field and related fields and through repeated experiments, in order to solve the problems existing in the prior art. Summary of the invention

[0008] The purpose of the present invention is to provide a PDC drill bit that can adapt to deep high temperature and high pressure environments and ensure the life of the drill bit while improving the mechanical drilling speed.

[0009] In order to achieve the above-mentioned purpose, the present invention proposes a PDC drill bit, wherein the PDC drill bit includes a drill bit body, a water injection cavity is opened in the drill bit body, and a plurality of water outlets are opened at the end of the drill bit body, each of the water outlets is respectively connected with the water injection cavity, and a nozzle is respectively arranged in each of the water outlets, each of the nozzles is tubular and has an axially passing water outlet cavity, one end of each of the nozzles is a water outlet end, and the other end of each of the nozzles is a mounting end, each of the mounting ends is penetrated into the corresponding water outlet and rotatably cooperated with the inner wall of the water outlet, each of the water outlet ends protrudes outwardly from the end face of the drill bit body, and at least one notch connected with the water outlet cavity is opened on the side wall of each of the water outlet ends.

[0010] The PDC drill bit as described above, wherein the notches are respectively formed on two opposite side walls of the water outlet end.

[0011] The PDC drill bit as described above, wherein each of the notches is U-shaped.

[0012] The PDC drill bit as described above, wherein the inner wall surface of the nozzle is provided with a spiral liquid flow guide groove.

[0013] The PDC drill bit as described above, wherein the helix angle of the flow guide groove is 20 degrees.

[0014] The PDC drill bit as described above, wherein the inner wall surface of the nozzle has a metal alloy steel layer.

[0015] As described above, the PDC drill bit, wherein the nozzle is installed at the water outlet through a water eye sleeve, the water eye sleeve is cylindrical and has an axially through-going installation cavity, the water eye sleeve is penetrated through the water outlet and the outer wall of the water eye sleeve is fixedly connected to the inner wall of the water outlet, the nozzle passes through the installation cavity, and the nozzle and the water eye sleeve are rotatably connected through a bearing.

[0016] As described above, the PDC drill bit, wherein the bearing is a thrust bearing, and the bearing has a shaft ring and a seat ring, the shaft ring is sleeved with the nozzle, and the seat ring is sleeved with the water eye.

[0017] As described above, the PDC drill bit, wherein the mounting end protrudes out of the mounting cavity, and the outer diameter of the mounting end is larger than the outer diameter of the water outlet end to form a limiting step, and the bearing is arranged between the limiting step and the end face of the water eye sleeve.

[0018] The PDC drill bit as described above, wherein the PDC drill bit also includes a plurality of fixed blades arranged at the end of the drill bit body, the plurality of fixed blades are connected to the end of the drill bit body at equal intervals along the circumferential direction, a plurality of cutting teeth are arranged side by side on one side of each of the fixed blades, and each of the water outlets is respectively arranged between two adjacent fixed blades.

[0019] Compared with the prior art, the present invention has the following characteristics and advantages:

[0020] The PDC drill bit proposed in the present invention can reduce the temperature of the cutting teeth and assist in rock breaking through the nozzle, taking into account both the mechanical drilling speed and the life of the drill bit, and realizing the speed and efficiency improvement of deep wells and ultra-deep wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings described herein are only for explanation purposes and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the various components in the figures are only schematic, used to help understand the present invention, and are not specifically limited to the shapes and proportional dimensions of the various components of the present invention. Those skilled in the art can select various possible shapes and proportional dimensions to implement the present invention according to the teachings of the present invention.

[0022] Figure 1 A schematic diagram of the structure of the PDC drill bit proposed by the present invention;

[0023] Figure 2 It is a schematic diagram of the nozzle and the water eye cover after being assembled in the present invention;

[0024] Figure 3 It is a schematic diagram of the structure of the nozzle in the present invention;

[0025] Figure 4 It is a schematic diagram of the structure of the water eye cover in the present invention;

[0026] Figure 5 It is a structural schematic diagram of the bearing in the present invention.

[0027] Description of reference numerals:

[0028] 100. PDC drill bit; 10. drill bit body;

[0029] 20. Nozzle; 21. Water outlet;

[0030] 22. Mounting end; 23. Notch;

[0031] 24. Liquid flow guide groove; 25. Limiting step;

[0032] 30. Water eye sleeve; 40. Bearing;

[0033] 41. Shaft washer; 42. Seat washer;

[0034] 43. Steel ball; 50. Fixed blade;

[0035] 60. Cutting teeth. DETAILED DESCRIPTION

[0036] The details of the present invention can be more clearly understood with reference to the accompanying drawings and the description of the specific embodiments of the present invention. However, the specific embodiments of the present invention described herein are only used for the purpose of explaining the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should all be considered to belong to the scope of the present invention.

[0037] like Figures 1 to 5 As shown, the present invention proposes a PDC drill bit 100, which includes a drill bit body 10, a water injection cavity is opened in the drill bit body 10, and a plurality of water outlets are opened at the end of the drill bit body 10, each water outlet is respectively connected to the water injection cavity, and a nozzle 20 is respectively arranged in each water outlet, each nozzle 20 is tubular and has an axially through water outlet cavity, one end of each nozzle 20 is a water outlet end 21, and the other end of each nozzle 20 is a mounting end 22, each mounting end 22 is penetrated in the corresponding water outlet and rotatably cooperated with the inner wall of the water outlet, each water outlet end 21 protrudes outwardly from the end face of the drill bit body 10, and at least one notch 23 is opened on the side wall of each water outlet end 21.

[0038] The PDC drill bit proposed in the present invention has a nozzle 20 protruding from the end face of the drill bit body 10, and the water flow sprayed by the nozzle 20 can enter the deep formation, thereby enhancing the rock breaking efficiency and mechanical rotation speed of the deep formation; at the same time, a notch 23 is provided on the nozzle 20, so that the water flow can be scattered at the notch 23, thereby also being able to clean and cool the fixed blade wing 50 and the cutting tooth 60 arranged at the end of the drill bit body 10; further, the nozzle 20 is rotatably connected to the drill bit body 10, and the nozzle 20 can spin under the action of hydraulic force during drilling, further expanding the cleaning area of ​​the scattered water flow formed by the notch 23, improving the cooling effect on the fixed blade wing 50 and the cutting tooth 60, and thereby extending the service life of the drill bit.

[0039] In an optional embodiment of the present invention, notches 23 are respectively provided on two opposite side walls of the water outlet 21 to further increase the spraying area of ​​the scattered water flow formed by the nozzle 20 and improve the cooling effect.

[0040] In an optional example of this embodiment, each notch 23 is U-shaped. Preferably, the notch 23 is opened from the end surface of the water outlet end 21 to the end surface of the drill body 10, that is, the U-shaped notch 23 opens on the end surface of the water outlet, and the bottom surface of the U-shaped notch 23 is located near the end surface of the drill body 10, so as to further increase the spray area of ​​the scattered water flow formed by the notch 23.

[0041] Furthermore, the edges of the U-shaped notch 23 are all designed with rounded chamfers, thereby enhancing the erosion resistance of the edges.

[0042] In an optional embodiment of the present invention, a spiral liquid flow guide groove 24 is provided on the inner wall of the nozzle 20. When the drilling fluid flows through the nozzle 20, the liquid flow generates a reaction force on the nozzle 20 when passing along the spiral liquid flow guide groove 24, so that the nozzle 20 rotates at a certain speed under the action of the hydraulic force, thereby expanding the spray range of the nozzle 20; at the same time, the rotation of the nozzle 20 generates turbulence in the flow field at the bottom of the drill bit, thereby improving the efficiency of cuttings cleaning and reducing repeated crushing.

[0043] Preferably, the helical angle of the spiral liquid flow guide groove 24 is 20 degrees.

[0044] In an optional example, the inner wall of the liquid flow guide groove 24 has an anti-scouring coating to improve the anti-scouring property of the liquid flow guide groove 24 and reduce the resistance to the liquid flow when the liquid flows through.

[0045] In an optional example of the present invention, the inner wall surface of the nozzle 20 is covered with a metal alloy steel layer to prevent the nozzle 20 from breaking during the drilling process.

[0046] Preferably, the alloy steel layer is a high-toughness hard alloy steel layer.

[0047] In an optional embodiment of the present invention, the nozzle 20 is installed at the water outlet through a water eye sleeve 30. The water eye sleeve 30 is cylindrical and has an axially through-going installation cavity. The water eye sleeve 30 is inserted into the water outlet and the outer wall of the water eye sleeve 30 is fixedly connected to the inner wall of the water outlet. The nozzle 20 passes through the installation cavity, and the nozzle 20 is rotatably connected to the water eye sleeve 30 through a bearing 40.

[0048] In an optional example, the outer wall of the water eye sleeve 30 is threadedly connected to the inner wall of the water outlet.

[0049] In an optional example of this embodiment, the bearing 40 is a thrust bearing, and the bearing 40 has a shaft ring 41, a retainer and a seat ring 42 arranged in sequence along the axial direction of the bearing 40, and a plurality of accommodating holes are opened on the retainer, and a plurality of steel balls are arranged in the plurality of accommodating holes in a one-to-one correspondence, and each steel ball is respectively rollingly matched with the shaft ring 41 and the seat ring 42, and the outer diameter of the nozzle 20 is slightly smaller than the inner diameter of the water eye sleeve 30, and the inner diameter of the shaft ring 41 is slightly smaller than the inner diameter of the seat ring 42, and the shaft ring 41 is sleeved with the nozzle 20, and the seat ring 42 is sleeved with the water eye sleeve 30. The nozzle 20 and the water eye sleeve 30 are rotated together through the shaft ring 41 and the seat ring 42 to ensure that the nozzle 20 can smoothly realize self-rotation.

[0050] In an optional example, the mounting end 22 protrudes out of the mounting cavity, and the outer diameter of the mounting end 22 is larger than the outer diameter of the water outlet end 21 to form a limiting step 25, and the bearing 40 is arranged between the limiting step 25 and the end surface of the water eye sleeve 30. Preferably, the outer diameter of the limiting step 25 is the same as the outer diameter of the water eye sleeve 30. During installation, the nozzle 20, the bearing 40 and the water eye sleeve 30 can be pre-assembled and then installed as a whole into the water outlet.

[0051] In an optional example of the present invention, the PDC drill bit 100 also includes a plurality of fixed blade wings 50 disposed at the end of the drill bit body 10, the plurality of fixed blade wings 50 are connected to the end of the drill bit body 10 at equal intervals along the circumferential direction, a plurality of cutting teeth 60 are arranged side by side on one side of each fixed blade wing 50, and each water outlet is respectively arranged between two adjacent fixed blade wings 50, that is, at the root of the fixed blade wings 50.

[0052] In an optional example, the cutting tooth 60 is made of artificial diamond and has a cylindrical structure, with a Mohs hardness of more than 10 and a thickness of the diamond layer of 0.2-0.8 mm.

[0053] In an optional example, the PDC drill bit 100 is provided with three fixed blade wings 50, which are connected to the shoulder of the drill bit body 10 by the core of the drill bit body 10; the PDC drill bit 100 also includes two auxiliary blade wings, which only exist on the shoulder of the drill bit body 10.

[0054] Please refer to Figures 1 to 5 The specific implementation process of the PDC drill bit 100 proposed by the present invention is now described in detail in conjunction with an embodiment:

[0055] Step 1: The water eye sleeve 30 is connected to the nozzle 20 through the bearing 40 to form a U-shaped extended nozzle overall structure. The water eye sleeve 30 is installed at the water outlet of the drill body 10 through its lower thread. The installation result is as follows: Figure 1 As shown;

[0056] Step 2: The drill bit body 10 drives the fixed blade 50 to rotate under the action of the drill string torque, and the cutting teeth 60 bite into the rock under the action of the drilling pressure. Under the action of the rotation of the fixed blade 50, the cutting teeth 60 squeeze, shear and crush the rock;

[0057] Step 3: The drilling mud passes through the internal flow channel of the drill bit body 10, and forms a jet at the nozzle 20. The jet forms a scattering at the U-shaped notch 23. At the same time, the jet formed by the constraint of the inner wall surface (hardened and lengthened alloy steel layer) of the nozzle 20 acts on the bottom of the well in a concentrated manner, that is, a part of the fluid ejected from the nozzle 20 forms a scattering effect on the fixed blade 50 and the cutting tooth 60, and the other part forms a constrained jet acting on the bottom of the well;

[0058] Step 4: When the drilling mud flows through the spiral liquid flow guide groove 24 on the inner wall of the nozzle 20, a reaction force is generated on the nozzle 20. The nozzle 20 realizes self-spin under the action of hydraulic force. The scattered liquid flow formed at the U-shaped notch 23 produces a larger range of action under the action of the rotation of the nozzle 20, thereby improving the cooling effect of the cutting teeth and extending the working life of the cutting teeth. At the same time, the rotation of the nozzle 20 causes turbulence in the flow field at the bottom of the drill bit, thereby improving the efficiency of cleaning the cuttings and reducing repeated crushing. The cemented carbide steel layer constrains the jet to act on the bottom of the well in a concentrated manner, assisting in crushing the rock and increasing the mechanical drilling speed.

[0059] The PDC drill bit 100 proposed in the present invention helps to expand rock micro-cracks through the extended nozzle 20 with a U-shaped notch 23, and assists the cutting teeth in crushing rocks; liquid flow scattering is formed on both sides of the nozzle 20 through the notch 23, ensuring the cooling and rock cleaning of the front and rear cutting teeth 60, thereby achieving the effect of increasing the service life of the drill bit; at the same time, the rotation of the nozzle 20 causes turbulence in the bottom hole liquid flow, thereby increasing the range of action of the nozzle, driving the movement of rock cuttings, reducing the occurrence of repeated crushing, and achieving the effect of improving drilling efficiency.

[0060] The PDC drill bit 100 proposed by the present invention realizes the self-rotation and liquid flow scattering of the nozzle 20, which helps to improve the cooling efficiency of the drill bit cutting teeth, drive the movement of rock cuttings, reduce repeated crushing, and improve rock breaking efficiency.

[0061] The detailed explanation of the above-mentioned embodiments is only intended to explain the present invention so as to facilitate a better understanding of the present invention. However, these descriptions cannot be interpreted as limitations on the present invention for any reason. In particular, the various features described in different embodiments may also be arbitrarily combined with each other to form other embodiments. Unless there is a clear description to the contrary, these features should be understood to be applicable to any embodiment and are not limited to the described embodiments.

Claims

1. A PDC drill bit, characterized in that: The PDC drill bit comprises a drill bit body, a water injection cavity is provided in the drill bit body, a plurality of water outlets are provided at the end of the drill bit body, each of the water outlets is respectively connected with the water injection cavity, each of the water outlets is respectively provided with a nozzle, each of the nozzles is tubular and has an axially penetrating water outlet cavity, one end of each of the nozzles is a water outlet end, and the other end of each of the nozzles is a mounting end, each of the mounting ends is penetrated in the corresponding water outlet and rotatably matched with the inner wall of the water outlet, each of the water outlet ends protrudes outwardly from the end face of the drill bit body, and at least one notch connected with the water outlet cavity is provided on the side wall of each of the water outlet ends; Each of the notches is U-shaped; the bottom surface of the U-shaped notch is located close to the end surface of the drill body; The inner wall surface of the nozzle is provided with a spiral liquid flow guide groove, and the spiral rise angle of the spiral liquid flow guide groove is 20 degrees; The nozzle is installed at the water outlet through a water eye sleeve, and the water eye sleeve is cylindrical and has an axially penetrating installation cavity. A U-shaped notch is provided on the side wall of the water eye sleeve at one end facing the water outlet end; The water eye sleeve is inserted into the water outlet, and the outer wall of the water eye sleeve is fixedly connected to the inner wall of the water outlet; the nozzle passes through the installation cavity, and the nozzle and the water eye sleeve are rotatably connected via a bearing; The bearing is a thrust bearing, and the bearing has a shaft ring, a retainer and a seat ring which are sequentially arranged along the axial direction of the bearing, the retainer is provided with a plurality of accommodating holes, a plurality of steel balls are arranged in the plurality of accommodating holes in a one-to-one correspondence, each of the steel balls is respectively in rolling cooperation with the shaft ring and the seat ring, the outer diameter of the nozzle is smaller than the inner diameter of the water eye sleeve, the inner diameter of the shaft ring is smaller than the inner diameter of the seat ring, the shaft ring is sleeved with the nozzle, and the seat ring is sleeved with the water eye sleeve; The mounting end protrudes out of the mounting cavity, and the outer diameter of the mounting end is larger than the outer diameter of the water outlet end to form a limiting step, and the bearing is arranged between the limiting step and the end surface of the water eye sleeve.

2. The PDC drill bit according to claim 1, characterized in that: The notches are respectively formed on two opposite side walls of the water outlet.

3. The PDC drill bit according to claim 1, characterized in that: The inner wall surface of the nozzle has a metal alloy steel layer.

4. The PDC drill bit according to claim 1, characterized in that: The PDC drill bit also includes a plurality of fixed blades arranged at the end of the drill bit body, the plurality of fixed blades are connected to the end of the drill bit body at equal intervals along the circumferential direction, a plurality of cutting teeth are arranged side by side on one side of each of the fixed blades, and each of the water outlets is respectively arranged between two adjacent fixed blades.

Images