CN114776226B

CN114776226B - PDC drill bit with different inside and outside and manufacturing method of PDC drill bit

Info

Publication number: CN114776226B
Application number: CN202210420292.9A
Authority: CN
Inventors: 高德利; 刘维; 未九森
Original assignee: China University of Petroleum Beijing
Current assignee: China University of Petroleum Beijing
Priority date: 2022-04-21
Filing date: 2022-04-21
Publication date: 2023-06-23
Anticipated expiration: 2042-04-21
Also published as: CN114776226A

Abstract

The invention provides a PDC drill bit with different inside and outside and a manufacturing method of the PDC drill bit, wherein the PDC drill bit with different inside and outside comprises the following components: a bit center portion and a bit shoulder portion, the bit center portion being located within a nose portion of a crown curve of the PDC bit, the bit shoulder portion being located outside of the nose portion of the crown curve of the PDC bit; the center part of the drill bit is provided with a center part cutting tooth, and the shoulder part of the drill bit is provided with a shoulder part cutting tooth; the average value of the working areas of the center portion cutting teeth is smaller than the average value of the working areas of the shoulder cutting teeth. The PDC drill bit solves the technical problem that the mechanical drilling speed and the rock breaking efficiency of the PDC drill bit are limited.

Description

PDC drill bit with different inside and outside and manufacturing method of PDC drill bit

Technical Field

The invention relates to the technical field of oil and gas drilling, in particular to a PDC drill bit with different inside and outside and a manufacturing method of the PDC drill bit.

Background

PDC (Polycrystalline Diamond Compact ) drill bit is applied to breaking underground rock, and is a main rock breaking tool in the field of oil and gas drilling engineering. The cutting structure of PDC bits mainly includes primary cutting teeth and a crown curve. The main cutting teeth are cutting teeth which are positioned in the first row of each blade of the drill bit and are contacted with stratum first and are used for bearing the main rock breaking task, and are called main teeth for short. The crown curve is a curve enveloped by the highest points of all main teeth; the gage section of the bit, excluding the crown profile, involves only the main tooth section that cuts the broken rock, and does not include teeth that are not broken-rock functions, such as gage teeth at the gage of the bit, non-first row teeth (also called secondary teeth) for each blade. The nose of the crown curve is tangent to the reference plane and is the axially highest position of the whole drill bit. As shown in FIGS. 1 and 2, the primary teeth on the crown curve of the PDC bit shown in FIG. 1 are

Is a circular tooth of (a); in fig. 2, the inner ring is the nose position of the bit, the outer ring represents the maximum outer diameter of the bit, and the ratio of the inner ring diameter to the outer ring diameter is typically 30% -80%. The cutting structure of the PDC drill bit can be divided into an inner part and an outer part according to the radial position of the nose part: a bit center portion located inboard of the nose portion, and a bit shoulder located outboard of the nose portion.

With the continuous progress of drilling technology and tools, the rock breaking efficiency and the mechanical drilling speed of PDC drill bits are also continuously improved. However, the rate of penetration of PDC bits has entered a bottleneck period in recent years, and has not been significantly breached. Currently, PDC bits are significantly limited in rate of penetration and rock breaking efficiency in three specific applications.

In the first case, the default of drilling engineers and PDC bit manufacturers is that increasing the diameter of the PDC bit cutters can effectively increase the rate of penetration of the PDC bit. Under ideal drilling conditions, the rate of penetration of the PDC drill bit can be found by the following formula:

ROP＝60×DOC×RPM (3)

wherein ROP (Rate of penetration) is the rate of penetration of the drill bit, and ROP is in m/h; DOC (Depth of cut per revolution) is the draft of the PDC tooth, the DOC unit is m/rev; RPM (Revolutions per minute) is the rotational speed in rev/min RPM.

From equation 3, it can be seen that: the mechanical drilling speed of the PDC drill bit is in positive correlation with the penetration depth of the cutting teeth; the size of the cutting teeth is increased, and the blade height and the penetration depth of the cutting teeth are increased, so that the mechanical drilling speed of the PDC drill bit is effectively increased; the large-size cutting teeth can crush more rocks after rotating for one circle, and are also beneficial to generating massive volume crushing and increasing the rock breaking efficiency of the cutting teeth and the PDC drill bit, so that the rock breaking effect of 'large teeth fast cutting' is formed. However, at present, even if cutting teeth with very large sizes are adopted, the improvement of the mechanical drilling speed of the PDC drill bit is not obvious, so that the mechanical drilling speed of the PDC drill bit enters a bottleneck period in recent years, and no remarkable breakthrough exists. In addition, "drill holding" is easy to occur, because torque energy is stored in a twisted pipe column, once the torque energy is released, the rotating speed of the drill bit reaches 2-15 times of a normal value, the drill bit and the pipe column suffer serious torsional vibration, and severe torque fluctuation is caused, so that the drill bit and the pipe column are important reasons for damaging the PDC drill bit. The draft of the main teeth is controlled, the reaction torque is reduced, and the stick-slip is well inhibited. The Baker Hughes company research has found that stick-slip is a major cause of PDC bit failure in today's drilling applications. Therefore, a compromise has to be made between the aggressiveness of the cutting teeth and the reaction torque, thereby balancing the rate of penetration with the durability of the drill stability.

In the second case, for oil and gas exploration and development in the fields of unconventional, deep layer, deep water and the like, more drilling energy is consumed for cutting the rock in unit volume; moreover, as well depths continue to deepen, the drilling energy provided to PDC bits is also relatively limited due to the limitations of current drilling processes and drilling equipment. By combining the above factors, the PDC drill bit shows poor rock breaking effect and drilling efficiency when drilling deep stratum, and greatly increases the drilling period and the drilling cost.

In the third case, for a very large diameter

The PDC bit of the present invention is limited in the rate of penetration and the rock breaking efficiency.

In summary, there are currently technical problems with PDC bits in which the rate of penetration and rock breaking efficiency are limited.

Disclosure of Invention

The invention aims to provide a PDC drill bit with different inside and outside and a manufacturing method of the PDC drill bit, so as to solve the technical problem that the mechanical drilling speed and the rock breaking efficiency of the PDC drill bit are limited.

The above object of the present invention can be achieved by the following technical solutions:

the invention provides a PDC drill bit with different inside and outside, which comprises: a bit center portion and a bit shoulder portion, the bit center portion being located within a nose portion of a crown curve of the PDC bit, the bit shoulder portion being located outside of the nose portion of the crown curve of the PDC bit; the center part of the drill bit is provided with a center part cutting tooth, and the shoulder part of the drill bit is provided with a shoulder part cutting tooth;

the average value of the working areas of the center portion cutting teeth is smaller than the average value of the working areas of the shoulder cutting teeth.

In a preferred embodiment, the difference between the average of the working areas of the shoulder cutting teeth and the average of the working areas of the center cutting teeth is greater than or equal to 20% and less than or equal to 86% of the average of the working areas of the center cutting teeth.

In a preferred embodiment, the working area of the center cutting teeth is smaller than the working area of the shoulder cutting teeth.

In a preferred embodiment, the difference between the working area of the shoulder cutting teeth and the working area of the center cutting teeth is greater than or equal to 20% of the working area of the center cutting teeth.

In a preferred embodiment, the center cutting tooth comprises at least 3 small area cutting teeth having a smaller working area than the other cutting teeth on the crown curve.

In a preferred embodiment, at least part of the center cutting teeth are cutting teeth provided with a tine section.

In a preferred embodiment, the working area of the cutting teeth with tine sections is smaller than the working area of the circular teeth of the same diameter, and the difference between the two is greater than or equal to 10% of the working area of the cutting teeth with tine sections.

In a preferred embodiment, at least part of the shoulder cutting teeth are cutting teeth provided with a tooth section, or the shoulder cutting teeth are rounded teeth.

In a preferred embodiment, the cutting tooth provided with the tine section is an axe-shaped tooth, a curved cutter tooth or a concave axe-shaped tooth.

The invention provides a manufacturing method of a PDC drill bit, which comprises the following steps:

manufacturing a bit body, wherein the bit body comprises a bit center part and a bit shoulder part, the bit center part is positioned in the nose part of the crown curve of the PDC bit, and the bit shoulder part is positioned outside the nose part of the crown curve of the PDC bit;

manufacturing a center cutting tooth and a shoulder cutting tooth, wherein the working area of the center cutting tooth is smaller than that of the shoulder cutting tooth;

the center portion cutting teeth are disposed at the bit center portion and the shoulder cutting teeth are disposed at the bit shoulder.

The invention has the characteristics and advantages that:

the PDC drill bit provided by the invention effectively improves the overall rock breaking efficiency and the mechanical drilling rate of the PDC drill bit, improves the rock breaking effect of the PDC drill bit, and has the following advantages:

(1) The high-speed rock breaking effect of 'large tooth fast cutting' is brought into play, and the large-scale acceleration of the stratum with better drillability can be realized;

(2) The difficult problem that deep stratum is difficult to eat is effectively solved, and the drilling energy required by the rock breaking of the PDC drill bit of the deep stratum is effectively reduced, so that the difficult problems of low drilling speed and long period of the deep stratum are solved;

(3) The cutting teeth at the center of the drill bit are provided with the sharp tooth parts, so that the penetration effect of the cutting teeth is improved, the working area is reduced, the drilling energy required by rock breaking of the cutting teeth is effectively reduced, the blocking effect of the cutting teeth at the center of the drill bit is eliminated, and the rock breaking efficiency of the PDC drill bit is greatly improved;

(4) The cutting teeth at the center of the drill bit are provided with the sharp-tooth parts, so that the drill bit is beneficial to eating a compact and hard stratum, the required weight on bit and torsion force are smaller, and the advantages are more obvious in long horizontal section or deep stratum drilling;

(5) The cutting teeth at the center of the drill bit are provided with sharp tooth parts, and become sharp, so that the ridge height is increased, and the transverse stability of the drill bit is improved;

(6) The cutting teeth at the center of the drill bit are provided with sharp tooth parts, the working area of the cutting teeth is reduced, the reaction torque is reduced, and the drilling energy required by one rotation of the center of the drill bit is reduced;

(7) The cutting teeth at the center of the drill bit are provided with sharp tooth parts, the working area of the cutting teeth is reduced, torque fluctuation is reduced, stable drill bit torque is facilitated, and the occurrence of vibration, stick-slip and bit bouncing of the drill bit is reduced;

(8) The cutting teeth at the center of the drill bit are provided with sharp tooth parts, the working area of the cutting teeth is reduced, the rock breaking amount of the drill bit rotating for one circle is reduced, the rock carrying and discharging are facilitated, the bottom of the well is cleaned, repeated cutting at the bottom of the well is facilitated to be reduced, and the rock breaking efficiency is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a typical crown profile for a PDC bit;

FIG. 2 is a top view of a typical crown curve of a PDC bit;

FIG. 3A is a schematic illustration of the working area of a 16mm diameter cutting tooth;

FIG. 3B is a schematic illustration of the working area of a 22mm diameter cutting tooth;

FIG. 4 is a programmed chart of a typical working area of a first blade of a PDC bit;

FIG. 5 is a graph of typical relationship between resultant force F of a PDC bit cutter and radial distance r thereof;

FIG. 6 is a schematic view of a circular tooth configuration;

FIG. 7 is a schematic view of the structure of an axe-shaped tooth;

FIG. 8 is a schematic view of the structure of curved cutter teeth;

FIG. 9 is a schematic view of a concave axe-shaped tooth;

FIGS. 10-14 are schematic structural views of different PDC bits provided by the present invention;

FIG. 15 is a schematic view of the construction of a horizontal drilling machine;

FIG. 16 is a schematic illustration of a comparison of rates of penetration;

FIG. 17 is a logical block diagram of PDC cutter work area calculation.

Reference numerals illustrate:

10. nose part; 11. a crown curve;

21. a drill bit center portion; 22. a bit shoulder;

30. cutting teeth; 301. a working surface;

31. a center cutting tooth; 32. shoulder cutting teeth;

40. a cutting tooth having a sharp tooth portion; 401. a tine section;

41. axe-shaped teeth; 42. bending cutter teeth; 43. concave axe-shaped teeth;

44. circular teeth;

51. a power propulsion device; 52. rock holder; 53. a drill string centralizer; 54. a drill string; 55. a slide rail; 56. a base; 57. a drill bit; 58. rectangular rock columns; 59. a slurry outlet; 510. a rock debris screen; 511. a rock debris slot; 512. a drilling pump; 513. a mud pit.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The inventor has studied the first case in the background art and found that: fig. 3A and 3B show the working surface 301 of the cutting tooth 30, the area of the working surface 301 of the cutting tooth 30 is the working surface of the cutting tooth 30, and a small-sized cutting tooth

Large-size cutting tooth +.>

A larger working area will result. According to formula 2, under the condition that the rock breaking stress is the same, the cutting teeth in the center of the drill bit can bear larger force due to larger working area, and the larger force is required for correspondingly breaking the rock.

F＝A×σ (2)

Wherein A is the contact working area between the cutting tooth and the rock, and is related to the position of the crown curve 11 where the cutting tooth is positioned; σ is the rock breaking stress and is related to the rock characteristic parameter and the rock breaking movement pattern.

The increase of the working area of the cutting teeth can obviously improve the blocking effect of the cutting teeth at the center of the drill bit, and the drill bit consumes more drilling energy after one revolution. Thus, even with very large-sized cutters, the increase in the rate of penetration of PDC bits is not significant, resulting in the rate of penetration of PDC bits entering the bottleneck period in recent years.

In addition, as the size of the cutting teeth increases and the working area thereof increases, a greater reaction torque is also created. The PDC drill bit can stop at any time due to the overlarge reaction torque, so that a drill bit is blocked until the pipe column accumulates enough torque so that the drill bit rotates again to shear the rock. Since torque energy is stored in a twisted string, once released, the string acts like a spring that unwinds, at which time the rotational speed of the drill bit will reach 2-15 times the normal value, the drill bit and string experience severe torsional vibrations, a phenomenon known as stick-slip. Stick-slip vibration will cause severe torque fluctuations, which are important causes of damage to PDC bits.

Through reasonable innovative technical scheme, if can reduce the blocking effect of bit center department jumbo size cutting tooth, and reduce jumbo size cutting tooth's reaction moment of torsion, this will be favorable to more exerting "big tooth fast-cutting" broken rock effect of formula 3, is favorable to improving the stability and the durability of drill bit to effectively improve the rate of penetration and broken rock efficiency of PDC drill bit.

The inventor has studied the second case in the background art and found that: as the well depth is increased, the formation lithology is compacted and compacted, the formation drillability is poor, and more drilling energy is consumed by cutting the rock in unit volume; as the formation compacts, the drilling energy required to break the rock increases, causing the retarding effect of the cutting teeth in the center of the bit to be amplified.

If the blocking effect of the cutting teeth in the center of the drill bit can be reduced when drilling deep formations, for example: by means of the method for reducing the working area of the cutting teeth (according to the formula 2) and the design of the tooth profile of the cutting teeth which is easier to eat into a compact stratum, the PDC drill bit consumes less drilling energy after rotating and cutting for one circle, so that the mechanical drilling speed and the rock breaking efficiency of the PDC drill bit for the deep stratum are effectively improved.

The inventor finds out after researching the third condition in the background technology; for very large diameters

As shown in fig. 2, as the radial distance r from the center of the drill increases, the corresponding linear velocity (formula 1) increases accordingly, thereby having higher rock breaking capacity and rock breaking efficiency. And because the drillability of the drilled area tends to be relatively good, large diameter PDC bits typically employ large size cutting teeth to increase the rate of penetration. However, the cutting teeth in each region of the PDC bit crown curve 11 still perform a single revolution of shear breaking at the same time, and the effect of drag from the large size cutting teeth in the center of the bit becomes significant.

Through a reasonable innovative technical scheme, if the blocking effect can be reduced, the mechanical drilling speed and the rock breaking efficiency of the large-diameter PDC drill bit can be effectively improved.

Typically, the cutting structure of PDC bits typically employs cutting teeth of the same size and the same profile in the center of the bit and the bit shoulder 22, i.e., the inner and outer cutters of the bit are uniformly distributed. As shown in FIG. 1, both the center and the shoulder of the bit are 16mm diameter circular teeth 44.

The inventor analyzes the defect of consistent internal and external tooth distribution of the PDC drill bit and finds that: the cutting teeth in the center of the PDC drill bit have a great retarding effect on the shearing and rock breaking effects of the whole drill bit. According to the barrel effect, the rock breaking effect of the cutting teeth at the center of the drill bit is a short plate for determining the mechanical drilling speed of the PDC drill bit.

Regarding the retarding effect of the cutter at the center of the PDC bit, this finding was developed in accordance with the following:

according to 1: according to the formula 1, the closer the cutting tooth is to the center of the drill bit, the slower the linear speed, the longer the time required for breaking the rock with the same arc length, the slower the shearing and breaking speed and the poor effect.

Wherein, the liquid crystal display device comprises a liquid crystal display device,

is the linear velocity, r is the radial distance from the center of the bit, and ω is the angular velocity.

According to 2: as shown in fig. 4, the closer the cutting tooth is to the center of the drill bit, the larger the working area of the cutting tooth. Typically, the crown profile 11 has a much shorter arc length at the bit center 21 than at the bit shoulder 22. Therefore, the number of teeth in the center portion 21 of the drill is much smaller than the number of teeth in the shoulder portion 22 of the drill at the same width of the bottom hole projection surface, and the cutting area of the cutting teeth in the center portion 21 of the drill is larger than the cutting area of the cutting teeth in the shoulder portion 22 of the drill. The first blade is the blade where the cutting tooth closest to the center of the drill bit is located.

According to formula 2, under the condition that the rock breaking stress is the same, the cutting teeth in the center of the drill bit can bear larger force due to larger working area, and the larger force is required for correspondingly breaking the rock.

According to 3: as shown in fig. 5, the closer the cutting teeth are to the center of the bit, the greater the resultant force F (pressure of weight on bit and Torque of rotation) the greater the induced reverse Torque (Reactive Torque) and Torque fluctuations, especially when lithology or weight on bit changes, will result in severe torsional fluctuations throughout the PDC bit.

According to 4: according to formula 2, the closer the cutting tooth is to the center of the drill bit, the larger the rock breaking stress is influenced by the rock breaking movement mode of the cutting tooth, and the larger the reaction force on the unit working area of the cutting tooth becomes along with the reduction of the rotation movement radius of the cutting tooth, the larger the energy required for rotationally shearing rock breaking, namely, the larger drilling energy is required to be consumed by the cutting tooth at the center of the drill bit compared with the cutting teeth in other areas. When the drill bit works underground, the cutting teeth of each region of the PDC bit crown curve 11 simultaneously complete one-circle rotation shearing rock breaking, but the cutting teeth of each region of the drill bit have different resistances to the drill bit rotation shearing rock breaking. The central area of the drill bit has large working area and high rock breaking stress, and more drilling energy is required to be consumed to complete rotation.

Therefore, the area with high rock breaking efficiency in the PDC drill bit cutting structure is limited by the central area of the drill bit with low rock breaking efficiency (wood barrel effect), and the whole drill bit cannot exert the optimal rock breaking effect. Conversely, if the blocking effect of the cutting teeth at the center of the drill bit can be reduced, the rock breaking efficiency and the mechanical drilling speed of the PDC drill bit can be effectively improved.

In order to solve the technical problems that the mechanical drilling speed and the rock breaking efficiency of the PDC drill bit are limited, the PDC drill bit is improved.

Scheme one

The present invention provides a PDC bit having different inside and outside, as shown in fig. 10 to 14, the PDC bit comprising: a bit center portion 21 and a bit shoulder portion 22, the bit center portion 21 being located within the nose portion 10 of the crown curve 11 of the PDC bit, the bit shoulder portion 22 being located outside the nose portion 10 of the crown curve 11 of the PDC bit; the bit center portion 21 is provided with center portion cutting teeth 31, and the bit shoulder portion 22 is provided with shoulder portion cutting teeth 32; the average value of the working areas of the center portion cutting teeth 31 is smaller than the average value of the working areas of the shoulder cutting teeth 32. The PDC drill bit with different inside and outside can effectively solve the difficult problem that deep stratum is difficult to eat, and effectively reduce the drilling energy required by the deep stratum PDC drill bit for breaking rock, thereby solving the difficult problems of low drilling speed and long period of the deep stratum.

The bit center portion 21 of the PDC bit is provided with one or more center portion cutters 31 and the bit shoulder portion 22 is provided with one or more shoulder portion cutters 32. The sum of the working areas of all the center cutting teeth 31 of the PDC bit is less than the sum of the working areas of all the shoulder cutting teeth 32. Further, the difference between the sum of the working areas of the shoulder cutting teeth 32 and the sum of the working areas of the center cutting teeth 31 is greater than or equal to 20% and less than or equal to 86% of the sum of the working areas of the center cutting teeth 31. As shown in fig. 2, the sum of the working areas of all the center-section cutting teeth 31 in the bit center section 21 and the sum of the working areas of all the shoulder center-section teeth in the bit shoulder 22 form a "inside-outside differential" bit cutting structure. More preferably, the difference between the sum of the working areas of the shoulder cutting teeth 32 and the sum of the working areas of the center cutting teeth 31 is less than or equal to 67.5% of the sum of the working areas of the center cutting teeth 31.

The number of center cutting teeth 31 and the number of shoulder cutting teeth 32 may be equal or unequal. In an embodiment, the average value of the working area of the center cutting tooth 31 is smaller than the average value of the working area of the shoulder cutting tooth 32 and the difference between the average value of the working area of the shoulder cutting tooth 32 and the average value of the working area of the center cutting tooth 31 is greater than or equal to 20% of the average value of the working area of the center cutting tooth 31 and less than or equal to 86% of the average value of the working area of the center cutting tooth 31. Specifically, the sum of the working areas of all the center-portion cutting teeth 31 of the drill center portion 21 is divided by the total number of teeth of the center-portion cutting teeth 31 to obtain an average value A1 of the working areas of the center-portion cutting teeth 31; similarly, the average value A2 of the working areas of the shoulder cutting teeth 32 can be obtained by dividing the sum of the working areas of all the shoulder cutting teeth 32 of the bit shoulder 22 by the total number of teeth of the shoulder cutting teeth 32, and the following conditions are satisfied: a1 < A2, and preferably A1×70%. Gtoreq.A1×20% (A2-A1). Gtoreq.A1×20%. More preferably, A1.times.67.5% > or (A2-A1) > or A1.times.20%.

Further, the working area of the center portion cutting tooth 31 is smaller than the working area of the shoulder cutting tooth 32, that is: the working area of each center cutting tooth 31 is smaller than the working area of the shoulder cutting tooth 32. Further, the difference between the working area of the shoulder cutting teeth 32 and the working area of the center cutting teeth 31 is greater than or equal to 20% of the working area of the center cutting teeth 31.

The working areas of the center cutting teeth 31 may be equal or unequal; the working areas of the shoulder cutting teeth 32 may or may not be equal. The inventors have further improved the PDC bit: the center cutter 31 of the PDC bit includes at least 3 small area cutters having a smaller working area than the other cutters on the crown curve 11. The working areas of the at least 3 small-area cutting teeth can be equal to each other or different from each other; preferably, the working areas of the at least 3 small-area cutting teeth are not equal to each other. For example: the center cutting tooth 31 of the PDC bit includes 4 small-area cutting teeth, that is: the working areas of the cutting teeth on the crown curve 11 rank from small to large the first, second, third and fourth cutting teeth, all belonging to the center cutting tooth 31.

The PDC drill bit cutting structure has the characteristic of being different between the inside and the outside, effectively solves the blocking effect of the cutting teeth at the center of the drill bit on the whole rock breaking effect of the drill bit, and improves the rock breaking efficiency of the PDC drill bit. In one embodiment, the overall diameter of the PDC bit is 75mm to 720mm and the number of blades of the PDC bit is 3 to 12. The enveloping circle diameter of the center cutting tooth 31 and the enveloping circle diameter of the shoulder cutting tooth 32 are each 8mm to 50mm, and specifically may be 13mm, 16mm, 19mm, 22mm, 25mm or 28mm.

The inventors have further improved the PDC bit: at least part of the center cutting teeth 31 are cutting teeth 40 having a tooth part. The center cutting tooth 31 in the PDC drill bit adopts the cutting tooth 40 with the sharp tooth part, so that the cutting effect of breaking through of sharp teeth can be formed, the capability of the cutting tooth at the center of the drill bit for cutting into the stratum is effectively improved, and the rock breaking efficiency of the cutting tooth at the center of the drill bit is more effectively improved.

The tooth surfaces of the cutting teeth 40 having the tooth sections, unlike the continuous smooth arcuate tooth surfaces of the circular teeth 44, have distinct intermittent and connective features, including lines, line links, line segments to arcuate lines, arcuate surface to arcuate surface links, and the like. As shown in fig. 6 to 9, the cutting tooth 40 having a tooth part is preferably an axe-shaped tooth 41, a curved cutter tooth 42, or a concave axe-shaped tooth 43. The cutting teeth 40 with the tine sections may also be other shaped teeth.

Further, the working area of the cutting teeth 40 having the tine sections is smaller than the working area of the circular teeth 44 having the same diameter, and the difference therebetween is greater than or equal to 10% of the working area of the cutting teeth 40 having the tine sections of the circular teeth 44.

Rounded teeth 44 have a continuous smooth arcuate tooth surface, and in some cases rounded teeth 44 are in the shape of a right circular cylinder; in other cases, the circular teeth 44 are projected as perfect circles and have a spoon-shaped concave structure or a spherical convex structure. In one embodiment, at least a portion of the shoulder cutting teeth 32 are cutting teeth 40 having pointed portions, or alternatively, the shoulder cutting teeth 32 are rounded teeth 44, i.e.: only part or all of the center cutting teeth 31 are cutting teeth 40 having a tooth section, or part or all of the shoulder cutting teeth 32 and part or all of the center cutting teeth 31 are cutting teeth 40 having a tooth section.

The PDC drill bit provided by the invention has the PDC drill bit cutting structure with 'inner and outer dissimilar' and 'sharp tooth breaking through', can effectively improve the overall rock breaking efficiency and the mechanical drilling speed of the PDC drill bit, improves the rock breaking effect of the PDC drill bit, and has the following advantages:

(3) The cutting teeth at the center of the drill bit are provided with the sharp tooth parts 401, so that the penetration effect of the cutting teeth is improved, the working area is reduced, the drilling energy required by rock breaking of the cutting teeth is effectively reduced, the blocking effect of the cutting teeth at the center of the drill bit is eliminated, and the rock breaking efficiency of the PDC drill bit is greatly improved;

(4) The cutting teeth at the center of the drill bit are provided with the sharp-tooth parts 401, so that the drill bit is beneficial to eating a compact and hard stratum, the required weight on bit and torsion force are smaller, and the advantages are more obvious in long horizontal section or deep stratum drilling;

(5) The cutting teeth at the center of the drill bit are provided with sharp tooth parts 401, and become sharp, so that the ridge height is increased, and the transverse stability of the drill bit is improved;

(6) The cutting teeth at the center of the drill bit are provided with the sharp tooth parts 401, the working area of the cutting teeth is reduced, the reaction torque is reduced, and the drilling energy required by one rotation of the center of the drill bit is reduced;

(7) The cutting teeth at the center of the drill bit are provided with the sharp tooth parts 401, the working area of the cutting teeth is reduced, torque fluctuation is reduced, stable drill bit torque is facilitated, and the occurrence of drill bit vibration, stick-slip and bit bouncing are reduced;

(8) The cutting teeth at the center of the drill bit are provided with the sharp tooth parts 401, the working area of the cutting teeth is reduced, the rock breaking amount of the drill bit rotating for one circle is reduced, the rock carrying and discharging are facilitated, the bottom of the well is cleaned, repeated cutting at the bottom of the well is facilitated to be reduced, and the rock breaking efficiency is improved.

The inventors have further optimized the PDC bit:

as shown in FIG. 10, the PDC drill bit has a diameter of 222.3mm and comprises 6 blades, and 9 cutter bending teeth 42 with a diameter of 16mm are arranged at the central part 21 of the drill bit; the other areas of the crown curve 11 are provided with circular teeth 44 of diameter 16 mm. Further, the difference between the working areas of the rounded teeth 44 and the curved teeth 42 is 28.8% of the working area of the curved teeth 42.

As shown in FIG. 11, the PDC drill bit has a diameter of 215.9mm and comprises 5 blades, and the drill bit central part 21 is provided with 8 cutter bending teeth 42 with a diameter of 16 mm; other areas of the crown curve 11 are provided with axe-shaped teeth 41 of 19mm diameter. The working area of the curved cutter tooth 42 is smaller than that of the hatchet-shaped tooth 41, and further, the difference between the working areas of the hatchet-shaped tooth 41 and the curved cutter tooth 42 is 45% of the working area of the curved cutter tooth 42.

As shown in FIG. 12, the PDC drill bit has a diameter of 311.2mm and comprises 5 blades, and a drill bit central part 21 is provided with 14 bent cutter teeth 42 with a diameter of 19 mm; other areas of the crown curve 11 are provided with axe-shaped teeth 41 of 19mm diameter. The working area of the curved cutter tooth 42 is smaller than that of the hatchet-shaped tooth 41, and further, the difference between the working areas of the hatchet-shaped tooth 41 and the curved cutter tooth 42 is 41.9% of the working area of the curved cutter tooth 42.

As shown in FIG. 13, the PDC bit has a diameter of 241.3mm and comprises 4 blades, and the bit center portion 21 is provided with 4 cutter bending teeth 42 with a diameter of 19 mm; the other areas of the crown curve 11 are provided with rounded teeth 44 of diameter 22 mm. Further, the difference between the working areas of the rounded teeth 44 and the curved teeth 42 is 64% of the working area of the curved teeth 42.

As shown in FIG. 14, the PDC drill bit has a diameter of 215.9mm and comprises 5 blades, and the drill bit central part 21 is provided with 7 bent cutter teeth 42 with a diameter of 16 mm; other areas of the crown curve 11 are provided with hatchet teeth 41 having a diameter of 16 mm. The working area of the bent cutter tooth 42 is smaller than that of the hatchet-shaped tooth 41, and further, the difference between the working areas of the hatchet-shaped tooth 41 and the bent cutter tooth 42 is 25.8% of the working area of the bent cutter tooth 42.

The PDC drill bit is tested by the inventor, a full-size drill bit rock breaking experimental platform is designed and established, drilling parameters such as weight on bit, drilling speed, pumping pressure and the like can be truly simulated, the PDC drill bit is suitable for researching drilling performance performances such as mechanical drilling speed, stability and the like of the drill bit, and the PDC drill bit has very important significance for optimizing drilling parameters such as weight on bit, rotating speed and the like. The experimental platform mainly comprises a horizontal drilling machine and a measurement while drilling nipple installed near a drill bit. The maximum drilling pressure of the horizontal drilling machine is 250KN, the maximum rotating speed is 160rev/min, and the maximum torque is 10000 N.m.

The horizontal drill bit can simulate the drilling behavior of a full-size drill bit downhole. The horizontal drilling machine comprises a rock clamping device, a drilling power device, a high-pressure drilling pump, a rock debris collecting box and a data collecting system. The rock clamping device can clamp 2000×350×350mm rock, and the rock can be set by itself according to stratum environment. The drilling power device consists of a feeding system and a rotating system, wherein the feeding system can provide a drilling pressure of 0-250KN for the drill bit and a moving distance of 2m (limited by the rock length), and the rotating system can provide a rotating speed of maximum 160r/min and a torque of maximum 10000N.m for the drill bit. In the experiment, through adjusting rig parameter, can realize the experimental purpose of accurate measurement drill bit various drilling behaviors. The data acquisition system of the full-size drill bit rock breaking experimental device can measure bit pressure, rotating speed, torque, footage, pump pressure, flow, axial vibration, radial vibration and circumferential vibration. The data sampling rate of the data acquisition system is maximally 1000HZ. The rock debris collecting box can collect rock debris generated in each drilling process, and is convenient for later analysis of the rock debris. Working principle: (1) installing rock in a rock holding device; (2) The drilling power device clamps the drill rod and provides drilling pressure and rotating speed for the drill bit in the drilling process; (3) the drill bit and the drill rod are buckled; (4) Pumping mud into a drill rod by a high-pressure drilling pump in the drilling process, cooling and lubricating a drill bit and effectively discharging rocks; (5) opening the data acquisition system before drilling: and (6) after drilling is finished, collecting the rock fragments in the rock fragment collecting box. Specifically, as shown in fig. 15, the horizontal drilling machine includes a power propulsion device 51, a rock holder 52, a drill string righting device 53, a drill string 54, a slide rail 55, a base 56, a drill bit 57, a rectangular rock column 58, a mud outlet 59, a cuttings screen 510, a cuttings pit 511, a drilling pump 512, and a mud pit 513.

Through full-size drill bit broken rock experiment platform, have carried out indoor test experiment to novel cutting structure design method PDC drill bit and conventional PDC drill bit. The PDC drill bit used in the experiment has the same main tooth crown curve 11 and exposure value, the diameter of the drill bit is 215.9mm (8.5-inch), the number of blades is 4, the only variable is the design method of the cutting structure, one is the design method of 'inside-outside dissimilarity' and 'sharp tooth breakthrough', and the other is the conventional 'inside-outside coincidence'. Specifically, the PDC drill bit adopts the cutting structure design method of 'inside and outside dissimilarity' and 'sharp tooth breakthrough' shown in FIG. 11, and the diameter of the drill bit is 215.9mm and comprises 4 blades; 4 curved cutter teeth 42 with a diameter of 19mm are used in the center of the bit, and circular teeth 44 with a diameter of 22mm are used in the shoulder 22 of the bit. The diameter of the conventional PDC drill bit is 215.9mm, and 4 blades are arranged; the crown curve 11 of the drill adopts the traditional tooth arrangement method of consistent inside and outside; the cutting teeth of the crown curve 11 are of the same size (Φ19 mm) and of the same tooth form (circular).

The rotating speed is set to be a constant value, the bit pressure is 1.5 tons and 2.5 tons, and as shown in fig. 16, the novel bit adopts the PDC bit with different inside and outside and provided by the invention, and compared with the conventional PDC bit, the speed is increased by more than 60%.

The inventors performed field trials on the PDC bit.

Test one: the PDC bit has the characteristic of "inside and outside dissimilarity" and "sharp tooth break-through", and with the PDC bit shown in fig. 13, a field test was performed in the C105 well of the shandong victory oilfield train western work block. Drilling the stratum mainly comprises: the fourth family of the new world is plain group, the newly-identified town group and the liberal pottery group, the ancient and near family east camp group and the sand river street group. The test results are shown in Table 1, and the PDC drill bit adopting the novel cutting structure design method creates the two records of the fastest mechanical drilling speed of the vehicle West operation block and the highest daily advance ruler-! Compared with the drill bit data of the adjacent well C27-X2 well, the novel drill bit realizes 160 percent of speed increase.

Table 1 bit usage data comparison

And (2) testing II: in the Y941-X71 well of Shandong victory oil field, the PDC drill bit provided by the invention and a conventional PDC drill bit are adopted to carry out the same-well test, the PDC drill bit shown in FIG. 14 is firstly used, and the conventional PDC drill bit is used immediately after the drilling. The adopted PDC drill bit with different inside and outside is provided with a cutting structure of 'different inside and outside' and 'break through' sharp teeth, and the diameter of the drill bit is 215.9mm and 5 blades are arranged; 7 curved cutter teeth with the diameter of 16mm are adopted at the center of the drill bit, and axe-shaped teeth with the diameter of 16mm are adopted at the shoulder of the drill bit. The diameter of the conventional PDC drill bit is 215.9mm, and 5 blades are arranged; the crown curve of the drill adopts the traditional tooth arrangement method of 'internal and external consistency', and the cutting teeth of the crown curve adopt the same size (phi 16 mm) and the same tooth shape (axe-shaped teeth). Drilling the stratum mainly comprises: sand three sections and midwifery. The test results are shown in table 2, and the speed increase was 65% by using the PDC bit having the different inside and outside compared to the conventional PDC bit.

Table 2 bit usage data comparison

And (3) test III: the PDC drill bit with different inside and outside is used in the field in the Y3-X14 well of the Xinjiang Pascal basin. The inside and outside differential PDC bit was identical to the inside and outside differential PDC bit in test two. Drilling the stratum mainly comprises: a calling wall group and a clear water river group. The test results are shown in Table 3, and the peripheral adjacent wells Y3-X2 adopt the PDC drill bit of Harbert of foreign enterprises, compared with the foreign enterprises, the foreign and the external PDC drill bit are adopted to realize the speed increase of 125%; the surrounding adjacent wells Y3-P16 adopt the imported PDC drill bit of the Schlenz, compared with the foreign and internal PDC drill bit, the speed is increased by 330 percent.

Table 3 shows comparison of the Using effects of the drill bit with the imported drill bit abroad

Scheme II

The invention provides a manufacturing method of a PDC drill bit, which comprises the following steps: manufacturing a bit body, wherein the bit body comprises a bit central part 21 and a bit shoulder part 22, the bit central part 21 is positioned in the nose part 10 of the crown curve 11 of the PDC bit, and the bit shoulder part 22 is positioned outside the nose part 10 of the crown curve 11 of the PDC bit; manufacturing a center cutting tooth 31 and a shoulder cutting tooth 32, wherein the working area of the center cutting tooth 31 is smaller than that of the shoulder cutting tooth 32; the center portion cutting teeth 31 are arranged in the bit center portion 21, and the shoulder cutting teeth 32 are arranged in the bit shoulder portion 22.

In order to effectively distinguish the working area of the cutter at the center of the bit from the working area of the cutter at the shoulder, the working area of the cutter on the PDC bit crown curve 11 may be calculated as follows. Specifically, by using a modern computer numerical method and using two computer languages of python and C++ as carriers, the working area calculation of the PDC bit cutting tooth arrangement design is realized through a computer graphic method. As shown in fig. 17, for a given PDC bit tooth layout design result parameter, including a radial position R, a rotation angle θ, and a height H of a spatial position parameter of each PDC cutting tooth, a spatial direction rotation angle back inclination angle α, a lateral rotation angle β, and an assembly angle γ of a working face of the PDC cutting tooth, 9 key calculation parameters such as serial numbers in an overall tooth layout structure, and preset generalized drilling parameters including a mechanical drilling rate and a bit rotational speed, are input into a calculation program, and a full-size bit idealized rotary drilling process around a bit axis is simulated by using spatial coordinate transformation in combination with a PDC bit geometry and a PDC bit motion correlation theory. The size of the working area of each PDC cutting tooth of the PDC drill bit tooth distribution structural design in the drilling parameter state can be obtained by carrying out the Boolean difference operation of the continuous PDC cutting tooth and the stratum rock mass.

The manufacturing method of the PDC drill bit can calculate the working area of PDC drill bit teeth with any different shapes, and has the characteristics of high calculation speed, convenient use, strong universality and good stability compared with calculation programs and calculation methods designed by other researchers because of using a C++ bottom programming language and a python glue programming language.

The foregoing is merely a few embodiments of the present invention and those skilled in the art may make various modifications or alterations to the embodiments of the present invention in light of the disclosure herein without departing from the spirit and scope of the invention.

Claims

1. A PDC bit having a dissimilar inside and outside comprising: a bit center portion and a bit shoulder portion, the bit center portion being located within a nose portion of a crown curve of the PDC bit, the bit shoulder portion being located outside of the nose portion of the crown curve of the PDC bit; the center part of the drill bit is provided with a center part cutting tooth, and the shoulder part of the drill bit is provided with a shoulder part cutting tooth;

the average value of the working areas of the center cutting teeth is smaller than the average value of the working areas of the shoulder cutting teeth;

the difference between the average of the working areas of the shoulder cutting teeth and the average of the working areas of the center cutting teeth is greater than or equal to 20% of the average of the working areas of the center cutting teeth and less than or equal to 86% of the average of the working areas of the center cutting teeth;

the working area of the center cutting teeth is smaller than that of the shoulder cutting teeth;

at least part of the center cutting teeth are cutting teeth with sharp tooth parts; at least part of the shoulder cutting teeth are cutting teeth with sharp tooth parts;

the working area of the cutting teeth with the sharp tooth parts is smaller than that of the circular teeth with the same diameter, and the difference value of the working area of the cutting teeth with the sharp tooth parts is larger than or equal to 10 percent of that of the cutting teeth with the sharp tooth parts.

2. The internally-externally-differentiated PDC bit of claim 1 wherein the difference between the working area of the shoulder cutter and the working area of the center cutter is greater than or equal to 20% of the working area of the center cutter.

3. The internally-externally-differentiated PDC bit of claim 1 wherein the center cutter comprises at least 3 small-area cutters having a smaller working area than the other cutters on the crown curve.

4. A PDC bit of any of claims 1-3 wherein the cutting tooth having a pointed tooth section is an axe-shaped tooth or a curved cutter tooth.

5. A method of manufacturing the dissimilar inside and outside PDC bits of claim 1 comprising: