WO2022205546A1

WO2022205546A1 - Self-excitation shaft punching and induced unloading coupling rock breaking drill bit and drilling speed-up method

Info

Publication number: WO2022205546A1
Application number: PCT/CN2021/089849
Authority: WO
Inventors: 刘永旺; 刘笑傲; 刘嘉雄; 管志川; 邹德永; 廖华林; 魏森; 张喆; 何鑫岩
Original assignee: 中国石油大学(华东)
Priority date: 2021-03-30
Filing date: 2021-04-26
Publication date: 2022-10-06
Also published as: CN113107371A

Abstract

A self-excitation shaft punching and induced unloading coupling rock breaking drill bit, comprising a drill bit body; an external annular rock breaking part (1) is provided at a drilling end of the drill bit body, and the middle part of a head end of the external annular rock breaking part (1) is concaved inwards to form a central rock breaking part (2); a plurality of blades (3) and a plurality of cones (4) embedded with cone cutting teeth (401) are provided on the external annular rock breaking part (1) in the circumferential direction; a plurality of outer ring cutting teeth (302) are provided on the radial outer end surfaces (301) of the blades (3) in a generatrix direction; central cutting teeth (201) are provided on a bottom end surface of the central rock breaking part (2); and a drill bit nozzle is provided on the drill bit body.

Description

Self-excited axial thrust and induced unloading coupled rock-breaking bit and drilling speed-up method

technical field

The invention belongs to the technical field of drilling engineering, and in particular relates to a self-excited axial thrust and induced unloading coupled rock-breaking drill bit and a drilling speed-up method.

Background technique

Improving drilling speed has always been a research hotspot in the field of drilling engineering, and improving rock breaking efficiency is one of the most important ways to improve drilling speed. Rotary impact rock breaking, composite cutting rock breaking and bottom hole induced unloading rock breaking are three effective methods to improve rock breaking efficiency at present. However, the impact force that the existing rotary impact rock breaking relies on is generated by special tools. The existence of the rotary impact tool affects the trajectory control operation, reduces the hydraulic energy of the drill bit and brings additional downhole risks; the current composite cutting rock breaking tools It is a composite drill bit (liger), which still has accidents such as tooth chipping, loss of cones and center "core" in multi-layered formations and hard and difficult-to-drill formations; The rock breaking efficiency is improved to a certain extent, but its unloading effect needs to be further improved.

Based on the above problems, the present application proposes a self-excited axial impact and induced unloading coupled rock-breaking drill bit and a drilling speed-up method. The drill bit and the drilling method can automatically generate axial impact to improve the overall rock-breaking speed of the drill bit, and can couple the induced unloading effect. To further strengthen the rock-breaking efficiency, it can exert the effect of composite cutting to lift and unload, so as to increase the drilling speed to a higher level.

technical solutions

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to provide a self-excited axial thrust coupled with an induced unloading rock-breaking bit and a drilling speed-up method.

To achieve the above object, the present invention adopts the following technical solutions:

Self-excited axial punch and induced unloading coupled rock-breaking bit, including the bit body;

The drilling end of the drill bit body is provided with an outer annular rock breaking part, and the middle part of the head end of the outer annular rock breaking part is concave inward along the axial direction of the drill bit to form a central rock breaking part in the form of a circular groove;

The outer annular rock-breaking part is provided with a plurality of blades and a plurality of cones inlaid with the cutting teeth of the cones along the circumferential direction;

The blade extends from the edge of the central rock breaking part to the side wall of the drill body;

The roller is rotatably connected with the corresponding journal on the outer annular rock breaking part;

A plurality of outer ring cutting teeth are arranged along the generatrix direction on the radial outer end face of the blade;

The bottom end face of the central rock-breaking portion is provided with central cutting teeth;

The drill bit body is provided with a drill bit nozzle, and the drill bit nozzle communicates with the drill bit inner cavity inside the drill bit body through the nozzle flow channel.

Preferably, the vertical connection surface of the blade facing the central rock-breaking part is cylindrical structure;

The vertical connecting surfaces of all blades are located on the same axial cylindrical surface, and the central axis of the axial cylindrical surface and the central axis of the central rock-breaking portion are both collinear with the central axis of the drill bit body;

The diameter of the axial cylindrical surface is consistent with the diameter of the circular groove of the central rock breaking part.

Preferably, the sum h of the height of the vertical connection surface in the axial direction of the drill bit and the height of the side wall of the circular groove of the central rock-breaking portion in the axial direction of the drill bit is 0.2D to 2D;

The diameter d of the circular groove of the central rock-breaking portion is 0.2D-0.8D, and D is the diameter of the drill bit.

Preferably, the outermost cutting contour envelope l ₁ formed by the cutting teeth on the roller cone is higher than the outermost cutting contour envelope l ₂ formed by the outer ring cutting teeth on the blade.

Preferably, the drill nozzle comprises an outer ring nozzle arranged on the outer annular rock breaking part on one side of the blade, and a central nozzle arranged on the bottom end face of the central rock breaking part;

The chip removal channel provided in the outer annular rock breaking part communicates with the chip removal channel provided in the central rock breaking part.

Preferably, the outer ring cutting teeth and the center cutting teeth are both PDC teeth.

Preferably, the PDC teeth are multi-edge PDC cutting teeth, the tooth body end of the multi-edge PDC cutting teeth is cylindrical, and the rock-breaking end of the multi-edge PDC cutting teeth includes several layers from the center radially outwards The cutting tooth surfaces are arranged in a stepped distribution, and the cutting tooth surfaces of each layer are parallel.

Preferably, the PDC teeth are ancient coin-shaped PDC cutting teeth, the tooth body end of the ancient coin-shaped PDC cutting teeth is a cylinder, the rock-breaking end of the ancient coin-shaped PDC cutting teeth is an arc structure, and the The radial outer end of the arc surface structure is provided with several cutting surfaces, and an arc-shaped cutting edge curved toward the center of the PDC teeth is formed between the cutting surfaces and the arc-shaped structure.

The invention also provides a speed-up method for rock-breaking drilling coupled with self-excited axial thrust and induced unloading.

Self-excited axial impulse and induced unloading coupled rock-breaking drilling speed-up method, based on self-excited axial impulse and induced unloading coupled rock-breaking drill bit for drilling, and the drilling speed-up method includes the following steps:

1) The outer annular rock-breaking part first contacts the bottom of the well, and the bit rotates as a whole under the action of the weight-on-bit torque, and the cone rotates as the bit rotates; the rotation of the cone causes the single tooth and double teeth of the cone cutting teeth to land alternately. , the reciprocating motion of the drill bit in the axial direction is caused during the alternate landing of the single and double teeth, thereby realizing the high-frequency axial impact of the drill bit on the bottom of the well. Breaking of the rock at the outer ring of the drill bit;

2) With the rock breaking of the outer ring cutting teeth and roller cones, a rock column is formed in the central rock breaking area, which effectively releases the bottom hole pressure;

3) As the rock breaking progresses, the central cutting teeth contact the rock column, and the central cutting teeth break the rock column under the action of the weight-on-bit torque;

4) During the rock-breaking and drilling process of the drill bit, the nozzle flow channel sprays drilling fluid through the drill bit nozzle to clean the drill bit, and the cuttings are carried to the ground through the corresponding chip removal channel.

Preferably, the co-action process of the roller cone and the outer ring cutting teeth under the high frequency axial impact is as follows:

When the cutting teeth on the cone on the cone change from double-tooth landing to single-tooth landing due to rotation, the drill bit is lifted as a whole, the outer ring cutting teeth on the blade leave the bottom of the well, and the cone cutting teeth touching the ground on the cone break the rock;

When the upper cone cutting teeth on the cone change from single-tooth landing to double-tooth landing due to rotation, the drill bit impacts downward as a whole, and the outer ring cutting teeth on the blade touch the ground, impacting and shearing the bottom hole after the stress of the cone is released.

beneficial effect

The beneficial effects of the present invention are:

(1) The present invention utilizes the indentation of the central rock-breaking part and the vertical connection surface on the blade to form a concave cylindrical area in the center of the drill bit. The formation of this area can release the rock stress in the center of the well bottom during the drilling process. Thus, induced unloading is achieved.

(2) The present invention utilizes the single and double teeth generated by the rotation of the cone to form the vibration of the drill bit in the axial direction, thereby forming a high-frequency axial impact and improving the overall rock breaking speed; at the same time, the uneven bottom hole formed by the cone is used. It can release the stress of the hard-to-drill part of the outer ring.

(3) The present invention realizes compound cutting through the combination of the upper outer ring cutting teeth of the blade, the upper cone cutting teeth and the center cutting teeth, and further improves the drilling speed.

(4) The arrangement of the multi-layer cutting tooth surfaces of the outer ring cutting teeth and the rock-breaking end of the central cutting tooth in the present invention is compared with the existing cutting teeth that only have a single-layer cutting tooth surface. , which increases the service life of the teeth.

(5) The setting of the ancient coin-shaped PDC cutting teeth at the rock-breaking end of the outer ring cutting teeth and the central cutting teeth in the present invention, compared with the existing cutting teeth, the setting of the ancient coin-shaped PDC cutting teeth of the present application can withstand high-strength impact and resist Grinding and ploughing reduce energy consumption and difficulty of rock breaking.

Description of drawings

The accompanying drawings that form a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute improper limitations on the present application.

1 is a schematic top view of the structure of a self-excited axial punch and an induced unloading coupled rock-breaking bit according to the present invention;

2 is a schematic front view of the structure of the self-excited axial punch and the induced unloading coupled rock-breaking bit of the present invention;

3 is a schematic diagram of the relationship between the outer annular rock-breaking part, the central rock-breaking part, the blade and the cone in the present invention;

4 is a schematic diagram of rock breaking when a single tooth of the cone of the present invention touches the ground;

5 is a schematic diagram of rock breaking when the double teeth of the cone of the present invention land on the ground;

6 is a schematic structural diagram of a multi-edge PDC cutting tooth whose cutting tooth surface is a plane in the present invention;

7 is a schematic structural diagram of a multi-edge PDC cutting tooth when the cutting tooth surface is a tapered surface in the present invention;

8 is a schematic structural diagram of a multi-edge PDC cutting tooth when the cutting tooth surface is a pyramid surface in the present invention;

9 is a schematic perspective view of the structure of an ancient coin-shaped PDC cutting tooth in Example 3 of the present invention;

10 is a schematic top view of the structure of an ancient coin-shaped PDC cutting tooth in Example 3 of the present invention;

11 is a schematic front view of the structure of an ancient coin-shaped PDC cutting tooth in Embodiment 3 of the present invention;

in:

1- External annular rock breaking part,

2-center rock breaking part, 201-center cutter, 202-bottom end face;

3-blade, 301-radial outer end face, 302-outer ring cutting teeth, 303-vertical connecting surface;

4-cone, 401-cone cutting teeth;

5- Outer Ring Nozzle,

6- Center nozzle;

701 - circular plane, 702 - annular plane;

801-cone surface, 802-ring cone surface;

901 - pyramid surface, 902 - annular pyramid surface;

1001-camber structure, 1002-cutting surface, 1003-camber cutting edge.

Embodiments of the present invention

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

In the present invention, terms such as "connected" and "connected" should be understood in a broad sense, indicating that it can be a fixed connection, an integral connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium. For the relevant scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to the specific situation, and should not be construed as a limitation of the present invention.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1:

As shown in Figure 1-2, the self-excited axial punch and the induced unloading are coupled to the rock-breaking bit, including the bit body;

The drilling end of the drill bit body is provided with an outer annular rock breaking part 1, and the middle part of the head end of the outer annular rock breaking part 1 is concave along the axial direction of the drill bit to form a central rock breaking part 2 in the form of a circular groove; The bottom end face 202 is a plane or an inner concave conical surface whose apex is located on one side away from the well bottom direction or an outer convex conical surface whose apex is located on one side close to the well bottom direction, or other shapes;

The outer annular rock breaking part 1 is provided with several blades 3 and several cones 4 inlaid with cone cutting teeth 401 along the circumferential direction; wherein, the blades 3 and the cones 4 can be alternately arranged as shown in FIG. 1 , It can also be arranged in other required forms, and this application does not limit the arrangement between the blade 3 and the cone 4;

The blade 3 extends from the edge of the central rock breaking portion 2 to the side wall of the drill body;

The roller 4 is rotatably connected with the corresponding journal on the outer annular rock breaking part 1; specifically, the tooth palm is fixed on the outer annular rock breaking part 1 in the middle between the adjacent blades 3, and one end of the tooth palm is welded to the drill bit body. As a whole, the other end of the tooth palm is provided with a journal; the roller 4 is sleeved on the journal to realize the rotational connection with the journal, and the roller 4 is axially locked on the journal, so that the roller 4 itself can rotate around the corresponding the journal rotation;

A plurality of outer ring cutting teeth 302 are arranged on the radially outer end surface 301 of the blade 3 along the generatrix direction;

The bottom end face of the central rock-breaking portion 2 is provided with central cutting teeth 201; specifically, a number of central blades are arranged on the bottom end face 202 of the central rock-breaking portion 2 along the circumferential direction, and a plurality of central cutting teeth are arranged on the end face of the central blade along the generatrix direction. 201;

The drill bit body is provided with a drill bit nozzle, and the drill bit nozzle communicates with the drill bit inner cavity inside the drill bit body through the nozzle flow channel, wherein the drill bit inner cavity is communicated with the drilling fluid flow channel.

Preferably, the vertical connecting surface 303 of the blade 3 facing the central rock-breaking portion 2 is a cylindrical structure;

The vertical connecting surfaces 303 of all blades 3 are located on the same axial cylindrical surface, and the central axis of the axial cylindrical surface and the central axis of the central rock breaking portion 2 are all collinear with the central axis of the drill bit body;

The diameter of the axial cylindrical surface is consistent with the diameter of the circular groove of the central rock breaking portion 2 .

Specifically, one end of the vertical connecting surface 303 extends along the axial direction of the drill bit to the head end of the radially outer end surface 301 on the corresponding blade 3, and the other end of the vertical connecting surface 303 extends along the axial direction of the drill bit to the center point The head end of the 2 circular grooves in the rock.

The self-excited shaft punch and the induced unloading coupling of the rock-breaking bit of the present invention, when drilling into a stratum with high ground stress, the outer ring cutting teeth 302 on the blade 3 and the cone cutting teeth 401 on the cone 4 firstly touch the drill bit. The rock at the outer ring is broken, and the broken cuttings are discharged into the wellbore annulus through the corresponding chip discharge channel along with the drilling fluid ejected from the outer discharge nozzle 5 .

The bottom end surface 202 of the central rock breaking part 2 is concave, and the vertical connecting surface 303 of the blade 3 is connected to the concave circular groove. Therefore, in the area surrounded by the vertical connecting surfaces 303 of all the blades 3, the central rock breaking part 2 The inner concave area forms an inner concave cylindrical area, that is, a stepped structure with inner concave and outer convexity is formed; in the process of drilling into the stratum, a "rock column" will be formed in the inner concave cylindrical area. When drilling into an area with high in-situ stress, the rock drillability is poor. The "rock column" formed by this stepped structure during the drilling process effectively reduces or even eliminates the influence of in-situ stress on the rock drillability, and greatly improves the rock drillability. Drillability, the "rock column" part forms a stress unloading area, which can effectively prevent the occurrence of "core digging". The central cutter 201 crushes the middle "rock column", and the formed cuttings are carried and flushed by the drilling fluid ejected from the central nozzle 6, and then discharged into the wellbore annulus through the corresponding chip removal channel.

Preferably, as shown in FIG. 3 , the sum h of the height of the vertical connecting surface 303 in the axial direction of the drill bit and the height of the side wall of the circular groove of the central rock breaking portion 2 in the axial direction of the drill bit is 0.2D to 2D;

The diameter d of the circular groove of the central rock breaking portion 2 is 0.2D-0.8D, and D is the diameter of the drill bit.

In this size range, the rock-breaking specific work of the drill bit is low, and the mechanical energy consumed by breaking a unit volume of rock is less, which is beneficial to prolong the life of the drill bit.

Preferably, the outermost cutting contour envelope l ₁ formed by the roller cone cutting teeth 401 on the cone 4 is higher than the outermost cutting contour envelope l ₂ formed by the outer ring cutting teeth 302 on the blade 3, As shown in Fig. 3, the cutter teeth 401 on the roller cone 4 first contact the bottom hole; in Fig. 3, l ₁ ' is the envelope of l ₁ mapped to the blade 3 side, and l ₁ ' is higher than l ₂ , so l ₁ is higher than l ₂ .

During the drilling process, the outer annular rock-breaking part 1 first contacts the bottom of the well, and the drill bit rotates as a whole under the action of the weight-on-bit torque, while the roller cone 4 rotates with the rotation of the bit; 401 Single and double teeth alternately touch the ground;

When the cutting teeth 401 on the cone 4 change from double-tooth landing to single-tooth landing due to rotation, the drill bit is lifted as a whole, the outer ring cutting teeth 302 on the blade 3 leave the bottom of the well, and the cones on the cone 4 are cut. The teeth 401 break rock, as shown in Figure 4;

When the cutting teeth 401 on the cone 4 change from single-tooth landing to double-tooth landing due to rotation, the drill bit impacts downward as a whole, and the outer ring cutting teeth 302 on the blade 3 touch the ground. The bottom of the well, as shown in Figure 5;

Therefore, the reciprocating motion of the drill bit in the axial direction is realized by the single and double teeth of the cone cutting teeth 401 alternately touching the ground, thereby realizing the high frequency axial impact of the drill bit on the bottom of the well, and accelerating the crushing of the rock at the outer ring of the drill bit.

Preferably, the drill bit nozzle includes an outer ring nozzle 5 arranged on the outer annular rock breaking portion 1 on one side of the blade 3, and a central nozzle 6 arranged on the bottom end face of the central rock breaking portion 2; wherein the outer ring nozzle 5 is cutting the outer ring The tooth 302 and the cone 4, the central nozzle 6 is facing the central cutting tooth 201, and the outer ring nozzle 5 and the central nozzle 6 work together. This structure ensures that the drilling fluid ejected from the nozzle can effectively clean and cool the rock. The cutting teeth at the parts avoid the repeated crushing phenomenon caused by the accumulation of cuttings;

The chip removal channel provided in the outer annular rock breaking portion 1 communicates with the chip removal channel provided in the central rock breaking portion 2 .

The nozzle flow channel, the outer ring nozzle 5 and the center nozzle 6 provide drilling fluid; the chip removal channel set in the outer annular rock breaking part 1 is used to discharge the cuttings produced by the outer ring cutting teeth 302 and the roller cone cutting teeth 401 into the wellbore Annulus; the chip removal channel provided by the central rock breaking part 2 is used to discharge the cuttings produced by the drilling of the central cutter 201 into the wellbore annulus.

Preferably, the outer ring cutting teeth 302 and the central cutting teeth 201 are both PDC teeth.

Example 2:

On the basis of Example 1, the PDC teeth are multi-edge PDC cutting teeth, the tooth body end of the multi-edge PDC cutting teeth is cylindrical, and the rock-breaking end of the multi-edge PDC cutting teeth includes several layers from the center The cutting tooth flanks are arranged radially outward in a stepped distribution, and the cutting tooth flanks of each layer are parallel.

When in use, the cutting tooth surface at the front end of the center first touches the rock to play a cutting role; when the rock is too hard or after a period of use, the cutting tooth surface in the center part is damaged and loses cutting effect, and the next layer of cutting tooth surface will play a role. cutting action. Compared with the existing cutting teeth having only a single-layer cutting tooth surface, the arrangement of the multi-edge PDC cutting teeth of the present application improves the service life of the teeth.

Wherein, the cutting tooth surface is a plane, a conical surface or a pyramidal surface, and may also be other shapes.

Specifically, as shown in FIG. 6 , the cutting tooth flank is a plane, the cutting tooth flank located at the foremost end in the center is a circular plane 701 , and the rest of the stepped cutting tooth surfaces are annular planes 702 .

Specifically, as shown in FIG. 7 , the cutting tooth surface is a conical surface, the cutting tooth surface located at the most front end of the center includes two intersecting conical surfaces 801 , and the remaining stepped cutting tooth surfaces are annular conical surfaces 802 .

Specifically, as shown in FIG. 8 , the cutting tooth surface is a pyramidal surface, the cutting tooth surface located at the frontmost end of the center includes a plurality of pyramidal surfaces 901 intersecting at one point, and the rest of the stepped cutting tooth surfaces are annular pyramidal surfaces 902. The same The extended surfaces of the layered annular pyramid surfaces 902 also intersect at one point, and the intersecting points of the pyramid surfaces 901 and the intersecting points of the annular pyramid surfaces 902 are both located on the central axis of the PDC teeth. Wherein, the structure when the cutting tooth surface located at the foremost end of the center includes three pyramid surfaces 901 is shown in FIG. 8 , and may also include other numbers of pyramid surfaces, which will not be listed one by one here.

Example 3:

On the basis of Example 1, as shown in FIGS. 9-11 , the PDC teeth are ancient coin-shaped PDC cutting teeth, the end of the tooth body of the ancient coin-shaped PDC cutting teeth is a cylinder, and the ancient coin-shaped PDC cutting teeth are cylindrical. The rock-breaking end of the PDC cutting teeth has an arc structure 1001, and the radial outer end of the arc structure 1001 is provided with a plurality of cutting surfaces 1002, and an arc curved toward the center of the PDC tooth is formed between the cutting surfaces 1002 and the arc structure 1001. Shaped cutting edge 1003.

Compared with the existing cutting teeth, the setting of the ancient coin-shaped PDC cutting teeth of the outer ring cutting teeth and the central cutting teeth in the present invention can withstand high-strength impact, resist grinding and pass Plow cutting to reduce energy consumption and difficulty of rock breaking.

Example 4:

Self-excited axial impulse and induced unloading coupled rock-breaking drilling speed-up method, based on the self-excited axial impulse and induced unloading coupled rock-breaking drill bit in Example 1, the drilling speed-up method includes the following steps:

1) The outer annular rock breaking part 1 first contacts the bottom of the hole, the bit rotates as a whole under the action of the WOB torque, and the roller cone 4 rotates with the bit rotation; The teeth touch the ground alternately, and the reciprocating motion of the drill bit in the axial direction is caused by the alternate landing of the single and double teeth, thereby realizing the high-frequency axial impact of the drill bit on the bottom of the well. Under the high-frequency axial impact, the cone 4 and the outer ring are cut. The joint action of the teeth 302 accelerates the breaking of the rock at the outer ring of the drill bit; at the same time, the uneven bottom hole formed by the cone can release the stress of the hard-to-drill part of the outer ring;

Specifically, the co-action process of the roller cone 4 and the outer ring cutting teeth 302 under the high-frequency axial impact is as follows:

When the cutting teeth 401 on the cone 4 change from single-tooth landing to double-tooth landing due to rotation, the drill bit impacts downward as a whole, and the outer ring cutting teeth 302 on the blade 3 touch the ground. the bottom of the well, as shown in Figure 5.

2) With the rock breaking progress of the outer ring cutter 302 and the roller cone 4, a rock column is formed in the area of the central rock breaking part 2, which effectively releases the bottom hole pressure;

3) As the rock breaking progresses, the central cutting teeth 201 contact the rock column, and the central cutting teeth 201 break the rock column under the action of the weight-on-bit torque;

The present invention utilizes the concave concave of the central rock breaking part 2 and the vertical connection surface 303 of the blade 3 to form a concave cylindrical area in the center of the drill bit. The formation of this area can release the rock stress in the center of the well bottom during the drilling process. In this way, the induced unloading is realized; the single and double teeth generated by the rotation of the cone 4 are used to form the vibration of the drill bit in the axial direction, thereby forming a high-frequency axial impact, and improving the overall rock breaking speed; using the upper outer ring of the blade 3 to cut The combination of the teeth 302, the cutting teeth 401 on the cone 4, and the central cutting teeth 201 realizes compound cutting and further improves the drilling speed.

Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they are not intended to limit the present invention. Those skilled in the art should understand that on the basis of the technical solutions of the present invention, those skilled in the art do not need to pay creative work. Various modifications or variations made are still within the protection scope of the present invention.

Claims

Self-excited axial punch and induced unloading coupled rock-breaking bit is characterized in that it includes a bit body;

The drilling end of the drill bit body is provided with an outer annular rock breaking part, and the middle part of the head end of the outer annular rock breaking part is concave inward along the axial direction of the drill bit to form a central rock breaking part in the form of a circular groove;

The outer annular rock-breaking part is provided with a plurality of blades and a plurality of cones inlaid with the cutting teeth of the cones along the circumferential direction;

The blade extends from the edge of the central rock breaking part to the side wall of the drill body;

The roller is rotatably connected with the corresponding journal on the outer annular rock breaking part;

A plurality of outer ring cutting teeth are arranged along the generatrix direction on the radial outer end face of the blade;

The bottom end face of the central rock-breaking portion is provided with central cutting teeth;

The drill bit body is provided with a drill bit nozzle, and the drill bit nozzle communicates with the drill bit inner cavity inside the drill bit body through the nozzle flow channel.
The self-excited axial punching and induced unloading coupled rock-breaking bit according to claim 1, wherein the vertical connecting surface of the blade facing the central rock-breaking part is a cylindrical structure;

The vertical connecting surfaces of all blades are located on the same axial cylindrical surface, and the central axis of the axial cylindrical surface and the central axis of the central rock-breaking portion are both collinear with the central axis of the drill bit body;

The diameter of the axial cylindrical surface is consistent with the diameter of the circular groove of the central rock breaking part.
The self-excited axial punch and induced unloading coupled rock-breaking bit according to claim 2, wherein the height of the vertical connecting surface in the axial direction of the bit and the side wall of the circular groove of the central rock-breaking part are at the axis of the bit. The sum of the heights in the direction h is 0.2D ~ 2D;

The diameter d of the circular groove of the central rock-breaking portion is 0.2D-0.8D, and D is the diameter of the drill bit.
The self-excited shaft punching and induced unloading coupled rock-breaking bit according to claim 1 , wherein the outermost cutting contour envelope l1 formed by the cutting teeth on the rollers is higher than that on the blade The outermost cutting contour envelope l 2 formed by the outer ring cutting teeth.
The self-excited axial punch and induced unloading coupled rock-breaking bit according to claim 1, wherein the bit nozzle comprises an outer ring nozzle arranged on the outer annular rock-breaking part on one side of the blade; central nozzle on the bottom end face;

The chip removal channel provided in the outer annular rock breaking part communicates with the chip removal channel provided in the central rock breaking part.
The self-excited shaft punch and induced unloading coupled rock-breaking bit according to claim 1, wherein the outer ring cutting teeth and the center cutting teeth are both PDC teeth.
The self-excited shaft punch and induced unloading coupled rock-breaking bit according to claim 6, wherein the PDC teeth are multi-edge PDC cutting teeth, and the end of the tooth body of the multi-edge PDC cutting teeth is cylindrical , the rock-breaking end of the multi-blade PDC cutting tooth includes several layers of cutting tooth surfaces arranged radially outward from the center in a stepped distribution, and the cutting tooth surfaces of each layer are parallel.
The self-excited shaft punch and induced unloading coupled rock-breaking bit according to claim 6, wherein the PDC teeth are ancient coin-shaped PDC cutting teeth, and the tooth body ends of the ancient coin-shaped PDC cutting teeth are Cylinder, the rock-breaking end of the ancient coin-shaped PDC cutting teeth has an arc structure, the radial outer end of the arc structure is provided with several cutting surfaces, and the cutting surface and the arc structure form a direction toward the center of the PDC tooth. Curved curved cutting edge.
The method for increasing the speed of rock-breaking drilling coupled with self-excited axial thrust and induced unloading is characterized in that the drilling is performed based on the self-excited thrust and induced unloading coupled rock-breaking drill bit according to any one of claims 1 to 8, and the drilling speed is increased. The method includes the following steps:

1) The outer annular rock-breaking part first contacts the bottom of the well, and the bit rotates as a whole under the action of the weight-on-bit torque, and the cone rotates as the bit rotates; the rotation of the cone causes the single tooth and double teeth of the cone cutting teeth to land alternately. , the reciprocating motion of the drill bit in the axial direction is caused during the alternate landing of the single and double teeth, thereby realizing the high-frequency axial impact of the drill bit on the bottom of the well. Breaking of the rock at the outer ring of the drill bit;

2) With the rock breaking of the outer ring cutting teeth and roller cones, a rock column is formed in the central rock breaking area, which effectively releases the bottom hole pressure;

3) As the rock breaking progresses, the central cutting teeth contact the rock column, and the central cutting teeth break the rock column under the action of the weight-on-bit torque;

4) During the rock-breaking and drilling process of the drill bit, the nozzle flow channel sprays drilling fluid through the drill bit nozzle to clean the drill bit, and the cuttings are carried to the ground through the corresponding chip removal channel.
The self-excited axial impact and induced unloading coupled rock-breaking drilling speed-up method as claimed in claim 9, characterized in that, under the high-frequency axial impact, the co-action process of the cone and the outer ring cutter is as follows:

When the cutting teeth on the cone on the cone change from double-tooth landing to single-tooth landing due to rotation, the drill bit is lifted as a whole, the outer ring cutting teeth on the blade leave the bottom of the well, and the cone cutting teeth touching the ground on the cone break the rock;

When the upper cone cutting teeth on the cone change from single-tooth landing to double-tooth landing due to rotation, the drill bit impacts downward as a whole, and the outer ring cutting teeth on the blade touch the ground, impacting and shearing the bottom hole after the stress of the cone is released.