CN115538946A

CN115538946A - Roller cone type composite PDC drill bit

Info

Publication number: CN115538946A
Application number: CN202211545772.4A
Authority: CN
Inventors: 任海涛; 贾新; 周春晓; 杨迎新; 周胜; 许敬伟
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2022-12-05
Filing date: 2022-12-05
Publication date: 2022-12-30
Anticipated expiration: 2042-12-05
Also published as: CN115538946B

Abstract

The invention discloses a cone type composite PDC drill bit, which comprises a bit body, fixed blades extending from the bit body and cones arranged on the fixed blades or bit legs, wherein cutting teeth are embedded on the fixed blades and the cones, and a mandrel of each cone is rotationally connected with a supporting blade or bit leg of the mandrel. The method is characterized in that: the oil storage assembly is arranged in the cone or the mandrel and sealed on the mandrel through the gland, and the gland is also provided with a one-way valve for controlling the one-way flow of the drilling fluid. The invention has the beneficial effects that: on one hand, under the fluctuation action of the pressure of the drilling fluid at the bottom of the well, the oil storage assembly is always maintained in a high-pressure state through the one-way valve, so that the bearing system can be lubricated more fully; on the other hand, the structure of a fixed blade or a cone leg for supporting the cone is simplified, the difficulty of machining and manufacturing processes is reduced, the structural strength is improved, and the assembly is simple and convenient.

Description

Roller cone type composite PDC drill bit

Technical Field

The invention belongs to the technical field of petroleum and natural gas drilling engineering, mine engineering, construction foundation engineering construction, geological drilling, tunnel engineering, hydrology, shield tunneling, trenchless and the like, and particularly relates to a drilling bit.

Technical Field

PDC bits are one of the most used rock breaking tools in drilling operations to break rock and form a wellbore. The PDC drill bit depends on a polycrystalline diamond compact which has high hardness, high wear resistance and self-sharpening to shear and crush rocks, and is widely used in drilling engineering due to high mechanical drilling speed, long service life and good drilling safety in soft to medium hard strata. Fixed cutter bits, typically PDC bits, typically have a plurality of blades with a plurality of cutting elements disposed radially along the bit (for PDC bits, the cutting elements are primarily polycrystalline diamond compacts, referred to as compacts or PDC teeth).

In the chinese patent No. 201010229371.9, filed at the university of petroleum in the south west, PDC teeth were first provided as the main cutting elements on a rotor (referred to herein as a cone) having a large offset angle (offset angle a is 20 ° or more and | a | or less than 90 °). The different motion modes of the two sets of cutting units form a cross net-shaped well bottom, and the rock breaking mode of cross cutting greatly improves the mechanical drilling speed of the drill bit. In another Chinese patent 'a composite cutting diamond bit' (patent number: 201710819577.9) filed at the southwest university of petroleum, a roller cone is arranged in a fixed blade or a water channel groove between the fixed blades to form a roller cone type composite PDC bit with a double-support structure. The stability of the roller bit is improved, and the cutting characteristics of the PDC bit are kept.

However, in the prior art including the above patent technologies, the oil storage assembly is arranged on the fixed blade or the bit leg, which results in a complicated structure and processing technique and a large manufacturing difficulty; the hole in which the oil reservoir assembly is located weakens the structural strength of the blade or bit leg, which can lead to a reduction in the overall safety of the drill bit. Meanwhile, in the prior art, pressure transmission holes are formed in the pressure cover, and lubricating grease in the oil storage assembly is extruded into a bearing system to realize lubrication under the pressure action of the drilling fluid. However, the drilling fluid always has pressure fluctuation, so that the oil storage assembly is pumped, lubricating grease can not be continuously supplied, and the lubricating effect on a bearing system is greatly reduced.

Disclosure of Invention

The invention aims to: aiming at the defects of the composite bit with the cone structure, the cone type composite PDC bit with a new structure is provided to simplify the bit structure, reduce the processing difficulty of the bit structure and improve the structural strength and the bearing lubricating effect of the bit.

The purpose of the invention is realized by the following technical scheme:

a cone type composite PDC drill bit comprises a drill bit body, a fixed blade extending from the drill bit body and a cone arranged on the fixed blade or a cone leg, wherein cutting teeth are embedded and fixed on the fixed blade and the cone, a mandrel of the cone is in rotary connection with a supporting blade or the cone leg, an oil storage assembly is arranged inside the cone or the mandrel and sealed on the mandrel through a gland, a one-way valve is further arranged on the gland, and the oil storage assembly is always kept in a high-pressure state through the one-way valve under the fluctuation action of the well bottom drilling fluid pressure.

Preferably, the mandrel is of a double-support structure, the front support blade and the rear support blade are respectively in rotary connection with the front support blade and the rear support blade in a front-rear mode, or the double-support rotary connection is formed on the same blade, an oil storage assembly is arranged inside the cone and sealed on the mandrel through a gland, and a check valve is further arranged on the gland.

In the scheme, the mandrel adopts a double-support structure, so that the space structure of the drill bit can be fully and reasonably utilized, and the rigidity and the rotation precision of the drill bit support body are improved.

Preferably, the roller cone is fixedly connected with the mandrel through a flat key or a spline.

In the scheme, the flat key and the spline are high in connection reliability, and the assembling and processing are simple and convenient.

Preferably, a hole is arranged in the mandrel, and lubricating grease is transmitted to the mandrel and the roller cone through the hole, and the mandrel and the rotor pair at the connecting position of the blade or the bit leg are connected.

In the scheme, the lubricating grease can rapidly flow to the surface of the rotating pair, the flowing path is short, the loss along the path is small, and the lubricating efficiency is high.

Preferably, a radial bearing or a thrust bearing is arranged at the joint of the mandrel and the fixed blade or the bit leg.

In the above scheme, when the cone rotates to drive the mandrel to rotate, the bearing can provide better rotation stability and higher rotation precision, and has the advantages of good wear resistance and the like.

Preferably, sealing rings are arranged between the mandrel and the fixed blades or the bit legs and between the mandrel and a rotating pair at the joint of the roller cone.

In the above scheme, the sealing ring can effectively block external abrasive particles from entering the revolute pair, and abrasion is reduced.

The technical scheme provided by the invention aims to provide a cone type composite PDC drill bit structure which is efficient in lubrication, simple in structure and good in stability, so that the existing cone-PDC composite drill bit or disc cutter type composite PDC drill bit can be used by the technical scheme provided by the invention.

The invention has the following beneficial effects:

1. under the fluctuation of the pressure of the drilling fluid at the bottom of the well, the oil storage assembly is always maintained in a high-pressure state through the one-way valve, and the lubricating grease can be continuously extruded into the bearing system, so that the lubricating effect on the bearing system is greatly improved.

2. The oil storage assembly is arranged in the cone, so that the structure of fixing the blades or the bit leg is simplified, and the difficulty of machining and manufacturing processes is reduced.

3. Compared with the conventional roller cone-PDC composite bit oil storage assembly arranged inside the bit leg, the technical scheme of the invention improves the structural strength and reliability of the bit (particularly fixed blades or bit leg).

4. The path of the pore passage through which the lubricating grease passes is short compared with the path of the lubricating grease of the conventional cone-PDC composite drill bit, the on-way loss on the path is small, and the lubricating capability and the lubricating effect are improved.

Drawings

The invention will be described by way of specific embodiments and with reference to the accompanying drawings in which:

FIG. 1 is a front view of a first embodiment of the present invention;

FIG. 2 is a top view of a first embodiment of the present invention;

FIG. 3 is a cross-sectional view of a cone according to a first embodiment of the present invention;

FIG. 4 is a top view of a second embodiment of the present invention;

FIG. 5 is a cross-sectional view of a cone of a second embodiment of the present invention;

FIG. 6 is a top view of a third embodiment of the present invention;

FIG. 7 is a cross-sectional view of a cone of embodiment three of the present invention;

FIG. 8 is a top view of a fourth embodiment of the present invention;

FIG. 9 is a cross-sectional view of a cone of a fourth embodiment of the present invention;

FIG. 10 is a cross-sectional view of a cone of embodiment five of the present invention;

FIG. 11 is a cross-sectional view of a cone of an embodiment six of the present invention;

reference numerals are as follows: 1-a bit body; 11-water eye; 2, fixing a blade; 21-front support blade; 22-rear support blade; 3, a palm of teeth; 4-a cone; 5, cutting teeth; 51-composite sheet teeth; 52-cemented carbide teeth; 6-a mandrel; 61-pore channel; 62-ball channel; 7-oil storage assembly; 81-flat bond; 82-spline; 83-rolling balls; 84-sealing ring; 841-second sealing ring; 842 — third seal ring; 85-a clamp spring; 86-a gland; 861-check valve; 91-radial bearing; 92-thrust sleeve.

Detailed Description

All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.

Any feature disclosed in this specification may, unless stated otherwise, be replaced by alternative features serving the same, equivalent or similar purpose. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

The invention will be further described with reference to specific embodiments and the accompanying drawings.

The first embodiment is as follows:

as shown in fig. 1, 2 and 3, a roller cone type composite PDC drill bit includes a bit body 1, a water hole 11, a fixed blade 2 and a bit leg 3 extending from the bit body 1, a roller cone 4 disposed on the bit leg 3, composite blades 51 embedded in both the fixed blade 2 and the roller cone 4, cutting teeth 5 being composite blades 51 or cemented carbide blades 52, and the roller cone 4 being capable of rotating with respect to its own spindle 6, wherein the roller cone 4 is of a disc cutter type structure. The mandrel 6 is axially locked and fixed on the bit leg 3 through a ball 83, and the cone 4 is fixedly connected with the mandrel 6 through a flat key 81. An oil storage assembly 7 is arranged inside the roller cone 4 and used for storing lubricating oil or lubricating grease which can be conveyed to the rotating pair through a hole 61 to realize lubrication. The cone 4 is also provided with a gland 86 which seals the oil storage assembly 7 in the cone 4 through a clamp spring 85, and the gland 86 is provided with a one-way valve 861. Balls 83 are mounted between the revolute pairs via ball passages 62 and sealing rings 84 are also provided between the cone 4 and the legs 3 to effect a seal.

In the conventional technology, the oil storage assemblies are all arranged inside the bit leg, and the hole for conveying the lubricating grease is generally a long hole and is also arranged in a staggered way with the ball passage. The bit leg is a special-shaped piece, has a complex structure and bears huge working load in drilling construction. Therefore, the traditional bit leg is not only difficult to process, but also is a wearing part of the composite drill bit, and the accident of bit leg breakage often occurs. In addition, in the prior art, the pressure transmission hole is formed in the pressure cover, and lubricating grease in the oil storage assembly is extruded into the bearing system under the pressure action of the drilling fluid to realize lubrication. However, the drilling fluid always has pressure fluctuation, so that the pumping effect is caused on the oil storage assembly, the lubricating grease can not be continuously supplied, and the lubricating effect on a bearing system is greatly reduced.

In the technical scheme, the oil storage assembly 7 is directly installed inside the cone 4, the gland 86 is provided with the one-way valve 861, and after lubricating grease is lost, the lubricating grease in the oil storage assembly 7 is directly conveyed to the rotating pair of the mandrel 6 through the hole 61 under the external drilling fluid pressure environment to realize lubrication.

In the technical scheme, under the fluctuation action of the pressure of the well drilling fluid at the bottom of the well, the oil storage assembly is always maintained in a high-pressure state through the one-way valve, and lubricating grease can be continuously extruded into a bearing system, so that the lubricating effect on the bearing system is greatly improved. Meanwhile, the simplification of the structure of the tooth leg can obviously reduce the processing and manufacturing difficulty and improve the structural strength.

Example two:

as shown in fig. 4 and 5, this embodiment is substantially the same as "embodiment one". The difference lies in that: the mandrel 6 and the bit leg 3 are of an integrated structure, and hard alloy teeth 52 are embedded in the cone 4; cone 4 is rotatable relative to spindle 6 without flat keys therebetween.

The embodiment is an innovative optimization application on the basis of a conventional cone-PDC composite bit, and aims to simplify the structure of the bit leg 3, improve the structural strength, reduce the manufacturing process difficulty and improve the lubricating effect of the bit.

Example three:

as shown in fig. 6 and 7, the present embodiment is substantially the same as the first embodiment. The difference lies in that: the mandrel 6 is supported by a front supporting blade 21 and a rear supporting blade 22, and is a double-supporting structure; a radial bearing 91 is also provided between the front support blade 21 and the spindle 6; a seal 84 is provided between the rear support blade 22 and the cone 4, a second seal 841 is provided between the forward support blade 21 and the spindle 6, and a third seal 842 is provided between the gland 86 and the forward support blade 21.

The embodiment is the innovation optimization application on the basis of the conventional double-support disc cutter composite PDC drill bit, the mandrel is supported by the front support blades and the rear support blades, the stability is better, the centering performance of the mandrel and the roller is good, the strength of the mandrel is weakened slightly, and the mandrel has the characteristics of larger load bearing capacity and high rotation precision.

Example four:

as shown in fig. 8 and 9, this embodiment is basically the same as "embodiment three". The difference lies in that: the mandrel 6 is longitudinally arranged on the fixed blade 2, and the front and rear supporting loads are borne by the fixed blade 2; hard alloy teeth 52 are embedded in the roller cone 4; a sealing ring 84 and a second sealing ring 841 are arranged between the mandrel 6 and the fixed blade 2, and a third sealing ring 842 is arranged between the gland 86 and the fixed blade 2.

The embodiment is innovative optimization application on the basis of a conventional double-support cone composite PDC drill bit, two ends of the mandrel are supported by the same blade, the mandrel has better stability, the mandrel and the cone can have good alignment, and the mandrel and the cone can bear larger load and have the characteristics of high rotation precision.

Example five:

as shown in fig. 10, this embodiment is substantially the same as "embodiment three". The difference lies in that: a thrust bearing 92 is also provided between the spindle 6 and the rear support blade 22.

The thrust bearing 92 is arranged in the embodiment, so that the supporting precision can be better realized, the abrasion resistance is higher, the rotation precision can be further ensured, and the service life can be further prolonged.

Example six:

as shown in fig. 11, this embodiment is substantially the same as "embodiment five". The difference lies in that: between the spindle 6 and cone 4 is a spline 82 connection.

In the embodiment, the gear wheel and the mandrel are connected through the spline, so that the gear wheel has better transmission bearing capacity.

Claims

1. A roller cone type composite PDC drill bit comprises a drill bit body, fixed blades extending from the drill bit body and a roller cone arranged on the fixed blades or a bit leg, wherein cutting teeth are embedded and fixed on the fixed blades and the roller cone, a mandrel of the roller cone is rotationally connected with the supporting blades or the bit leg, and the roller cone type composite PDC drill bit is characterized in that: the oil storage assembly is arranged in the cone or the mandrel and sealed on the mandrel through a gland, and a check valve is also arranged on the gland.

2. The roller cone composite PDC bit of claim 1, wherein: the spindle is of a double-support structure, the front support blade and the rear support blade are in rotary connection respectively in the front and the rear direction, or the double-support rotary connection is formed on the same blade, an oil storage assembly is arranged in the cone and sealed on the spindle through a gland, and a one-way valve is further arranged on the gland.

3. The roller cone type composite PDC drill bit of claim 1, wherein: the cone is fixedly connected with the mandrel through a flat key or a spline.

4. The roller cone composite PDC bit of claim 1, wherein: the spindle is internally provided with a pore passage, and the lubricating grease is conveyed to a revolute pair at the connecting position of the spindle and the cone, the spindle and the blades or the bit legs through the pore passage.

5. The roller cone composite PDC bit of claim 1, wherein: and a radial bearing or a thrust bearing is arranged at the joint of the mandrel and the fixed blade or the tooth leg.

6. The roller cone composite PDC bit of claim 1, wherein: and sealing rings are arranged between the mandrel and the fixed blade or the bit leg as well as between the mandrel and a revolute pair at the joint of the cone.