PDC Drill Bits

Abstract

The present invention provides a PDC drill bit, which comprises: a core blade and an outer cone blade distributed around the circumference of the PDC drill bit, the core blade is provided with a diameter protection structure and a core mounting surface with a composite piece cutting tooth installed, and the outer cone blade is provided with a diameter protection structure and an outer cone mounting surface with a composite piece cutting tooth installed; the maximum outer diameter R of the outer contour of the core mounting surface max , and the minimum outer diameter R of the inner contour of the outer cone mounting surface min Satisfaction: R max ≤(0.9·R 保径 ), and R min ≥(0.3·R 保径 The present invention alleviates the technical problem that the PDC drill bit in the prior art is prone to tilt when drilling in soft formations, causing the wellbore inclination to exceed the standard.

Description

Technical Field

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

[0002] PDC drill bits are widely used in drilling and rock breaking. The shear strength of the rock itself is smaller than its compressive strength. The rock breaking mechanism of PDC drill bits is mainly shearing. When drilling with PDC drill bits, a higher mechanical drilling speed can be obtained by providing a smaller drilling pressure. During the drilling process, the PDC drill bit itself has an unbalanced force and is affected by the fluctuation of the reverse torque. When drilling in soft formations, it is easy to tilt, causing the wellbore to exceed the standard and affecting the quality of the wellbore. Summary of the invention

[0003] The purpose of the present invention is to provide a PDC drill bit to alleviate the technical problem that the PDC drill bit in the prior art is prone to tilt when drilling in soft formations, causing the wellbore inclination to exceed the standard.

[0004] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0005] The present invention provides a PDC drill bit, comprising: a core blade and an outer cone blade distributed around the circumference of the PDC drill bit, the core blade being provided with a diameter protection structure and a core mounting surface on which a composite piece cutting tooth is mounted, and the outer cone blade being provided with a diameter protection structure and an outer cone mounting surface on which a composite piece cutting tooth is mounted;

[0006] The maximum outer diameter R of the outer contour of the core mounting surface max , and the minimum outer diameter R of the inner contour of the outer cone mounting surface min satisfy:

[0007] R max ≤(0.9·R 保径 ),

[0008] And R min ≥(0.3·R 保径 ).

[0009] In a preferred embodiment, a blade groove is provided on the core blade, and the blade groove is located outside the core mounting surface.

[0010] In a preferred embodiment, the diameter protection structure of the core blade is the same as the diameter protection structure of the outer cone blade.

[0011] In a preferred embodiment, the gauge guaranty structure includes a gauge surface and at least two gauge guaranty teeth fixed on the gauge surface.

[0012] In a preferred embodiment, the gauge surface is provided with an alloy column groove, and the gauge teeth are embedded in the alloy column groove with interference fit.

[0013] In a preferred embodiment, the PDC drill bit comprises three core blades and three outer cone blades, and the core blades and the outer cone blades are alternately distributed in sequence around the circumference of the PDC drill bit.

[0014] In a preferred embodiment, each of the outer conical blades is provided with three of the composite sheet cutting teeth; the three core blades include a first core blade, a second core blade and a third core blade which are distributed in sequence, the first core blade is provided with two of the composite sheet cutting teeth, and the second core blade and the third core blade are provided with three of the composite sheet cutting teeth.

[0015] In a preferred embodiment, the core blade has a first cutting surface and a first back cutting surface located on both sides of the core mounting surface, and the first cutting surface and the first back cutting surface are arranged obliquely relative to the axis of the PDC drill bit.

[0016] In a preferred embodiment, the outer cone blade has a second cutting surface and a second back cutting surface located on both sides of the outer cone mounting surface, and the second cutting surface and the second back cutting surface are inclined relative to the axis of the PDC drill bit.

[0017] In a preferred embodiment, a nozzle is provided on the front end surface of the drill crown of the PDC drill bit.

[0018] In a preferred embodiment, the number of the nozzles is 6.

[0019] In a preferred embodiment, auxiliary cutting teeth are respectively disposed on the first cutting surface and the second cutting surface.

[0020] The characteristics and advantages of the present invention are:

[0021] In this PDC drill bit, the distribution area of ​​the composite cutting teeth on the core blade is limited to R max ≤(0.9·R 保径 ), the distribution density of the cutting teeth of the composite piece of the core blade is reduced. While reducing the number of the composite piece cutting teeth, the single tooth of the core blade penetrates deeper into the formation and has stronger attack performance, which is beneficial for the PDC drill bit to drill at high speed in soft formations and improve the rock breaking and cutting efficiency; the distribution area of ​​the composite piece cutting teeth on the outer cone blade is limited to R min ≥(0.3·R 保径), while ensuring that the diameter-protecting structure of the PDC drill bit has a large contact area with the well wall, the repeated cutting of the formation by the composite piece cutting teeth at the outer cone position and the composite piece cutting teeth at the core position is reduced, thereby reducing the inclination of the PDC drill bit during drilling, playing a role in controlling well inclination and improving wellbore quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A top view of the PDC blade provided by the present invention;

[0024] Figure 2 for Figure 1 A first isometric view of the PDC blade shown;

[0025] Figure 3 for Figure 1 A second isometric view of the PDC blade shown;

[0026] Figure 4 A front view of the PDC blade provided by the present invention; .

[0027] Figure 5 for Figure 4 A side view of the PDC blade shown;

[0028] Figure 6 for Figure 4 A side view of a PDC blade is shown.

[0029] Description of Figure Numbers:

[0030] 10, core blade; 100, core mounting surface; 110, first cutting surface; 120, first back cutting surface;

[0031] 11. first core blade; 12. second core blade; 13. third core blade; 14. blade groove;

[0032] 20, outer cone blade; 200, outer cone mounting surface; 210, second cutting surface; 220, second back cutting surface;

[0033] 21. first outer conical blade; 22. second outer conical blade; 23. third outer conical blade;

[0034] 30. Gauge-keeping structure; 31. Gauge surface; 32. Gauge-keeping tooth; 321. First gauge-keeping tooth; 322. Second gauge-keeping tooth;

[0035] 40. Composite cutting teeth; 50. Auxiliary cutting teeth;

[0036] 60. Nozzle;

[0037] 71. Drill bit crown; 72. Joint structure. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The present invention provides a PDC drill bit, such as Figure 1 and Figure 4-Figure 6 As shown, the PDC drill bit includes a drill crown 71 and a joint structure 72, the drill crown 71 is provided with a core blade wing 10 and an outer cone blade wing 20, the core blade wing 10 and the outer cone blade wing 20 are circumferentially distributed around the axis of the PDC drill bit; the core blade wing 10 is provided with a diameter protection structure 30 and a core mounting surface 100 on which a composite piece cutting tooth 40 is installed, and the outer cone blade wing 20 is provided with a diameter protection structure 30 and an outer cone mounting surface 200 on which the composite piece cutting tooth 40 is installed; the core mounting surface 100 includes the top surface of the core blade wing 10, the outer cone mounting surface 200 includes the top surface of the outer cone blade wing 20, and the maximum outer diameter R of the outer contour of the core mounting surface 100 max , and the minimum outer diameter R of the inner contour of the outer cone mounting surface 200 min satisfy:

[0040] R max ≤(0.9·R 保径 ), and R min ≥(0.3·R 保径 ).

[0041] In the PDC drill bit, the distribution area of ​​the composite cutting teeth 40 on the core blade 10 is limited to R max ≤(0.9·R 保径 ), the distribution density of the composite cutting teeth 40 of the core blade 10 is reduced. While reducing the number of the composite cutting teeth 40, the single tooth of the core blade 10 penetrates deeper into the formation and has stronger attack performance, which is beneficial for the PDC drill bit to drill at high speed in soft formations and improve the rock breaking and cutting efficiency; the distribution area of ​​the composite cutting teeth 40 on the outer cone blade 20 is limited to R min ≥(0.3·R 保径), while ensuring that the diameter protection structure 30 of the PDC drill bit has a larger contact area with the well wall, the repeated cutting of the formation by the composite piece cutting teeth 40 at the outer cone position and the composite piece cutting teeth 40 at the core position is reduced, thereby reducing the inclination of the PDC drill bit during drilling, playing a role in controlling the well inclination and improving the wellbore quality.

[0042] In one embodiment of the present invention, a blade groove 14 is provided on the core blade 10, and the blade groove 14 is located outside the core mounting surface 100. The blade groove 14 defines the outer contour of the core mounting surface 100, and the blade groove 14 can improve the drilling fluid flow field of the drill bit core, which is beneficial to the discharge of cut rock cuttings.

[0043] like Figure 2 As shown, the PDC drill bit includes three core blades 10 and three outer cone blades 20, and the core blades 10 and the outer cone blades 20 are alternately distributed in sequence around the circumference of the PDC drill bit.

[0044] Further, each outer cone blade 20 is provided with three composite sheet cutting teeth 40; the three core blades 10 include a first core blade 11, a second core blade 12 and a third core blade 13 which are sequentially distributed, the first core blade 11 is provided with two composite sheet cutting teeth 40, the second core blade 12 and the third core blade 13 are provided with three composite sheet cutting teeth 40, so that each composite sheet cutting tooth 40 can be in uniform contact with the formation rock, and the force is more uniform. Preferably, the composite sheet cutting teeth 40 are welded in the tooth socket by a welding process, and the tail of the composite sheet cutting teeth 40 is further protected by a surfacing process.

[0045] Please refer to Figure 3 , along the direction from the inside to the outside, the first outer cone blade wing 21 is sequentially provided with composite sheet cutting teeth 1a, composite sheet cutting teeth 1b and composite sheet cutting teeth 1c, the second core blade wing 12 is sequentially provided with composite sheet cutting teeth 2a, composite sheet cutting teeth 2b and composite sheet cutting teeth 2c, the second outer cone blade wing 22 is sequentially provided with composite sheet cutting teeth 3a, composite sheet cutting teeth 3b and composite sheet cutting teeth 3c, the third core blade wing 13 is sequentially provided with composite sheet cutting teeth 4a, composite sheet cutting teeth 4b and composite sheet cutting teeth 4c, the third outer cone blade wing 23 is sequentially provided with composite sheet cutting teeth 5a, composite sheet cutting teeth 5b and composite sheet cutting teeth 5c, and the first core blade wing 11 is sequentially provided with composite sheet cutting teeth 6a and composite sheet cutting teeth 6b.

[0046] Each composite sheet cutting tooth 40 has its own first reference point; specifically, the front end surface of the composite sheet cutting tooth 40 is its cutting surface, and the first reference point is the center of the cutting surface of the composite sheet cutting tooth 40 .

[0047] A plane passing through the axis of the PDC drill bit is used as the reference plane of the PDC drill bit. Each composite cutter 40 has its own second reference point; the angle between the plane formed by the second reference point and the axis of the PDC drill bit and the reference plane is used as the position angle of the composite cutter 40. Preferably, the second reference point is the vertex of the cutting surface of the composite cutter 40 (i.e. Figure 4 and Figure 5 The highest point of the composite plate cutting tooth 40 is shown).

[0048] On the end face projection of the PDC drill bit, the first reference point and the second reference point of the composite cutting tooth 40 on the outer cone blade wing 20 are both located within the range defined by the outer cone mounting surface 200; the first reference point and the second reference point of the composite cutting tooth 40 on the core blade wing 10 are both located within the range defined by the core mounting surface 100.

[0049] In a specific embodiment, the position angle of each composite piece cutting tooth 40 is set as shown in the following table; the distance between the first reference point of each composite piece cutting tooth 40 and the axis of the PDC drill bit is set as shown in the following table.

[0050] Tooth number Position Angle Distance / mm 1a 70° 59 1b 73° 81 1c 72° 107 2a 12° 13 2b 11° 47 2c 13° 65 3a 315° 63 3b 317° 79 3c 318° 104 4a 260° 11 4b 263° 43 4c 267° 67 5a 204° 69 5b 207° 83 5c 211° 106 6a 152° 42 6b 155° 68

[0051] According to the above table, the position of each composite cutting tooth 40 is determined. The asymmetric structure is used to arrange the teeth so that the cutting amount of each composite cutting tooth 40 is equal or approximately equal during drilling, and each tooth is evenly loaded, which prolongs the life of the drill bit and improves the drilling efficiency.

[0052] In other embodiments, the position angle of each composite plate cutting tooth 40 may fluctuate by 2.5° based on the data in the above table, so as to ensure that the PDC drill bit has better drilling efficiency and wellbore quality.

[0053] In one embodiment of the present invention, please refer to Figure 3 The core blade 10 has a first cutting surface 110 and a first back cutting surface 120 located on both sides of the core mounting surface 100, and the first cutting surface 110 and the first back cutting surface 120 are inclined relative to the axis of the PDC drill bit.

[0054] The outer cone blade 20 has a second cutting surface 210 and a second back cutting surface 220 located on both sides of the outer cone mounting surface 200. The second cutting surface 210 and the second back cutting surface 220 are inclined relative to the axis of the PDC drill bit.

[0055] like Figure 2As shown, the gauge structure 30 includes a gauge surface 31 and at least two gauge teeth 32 fixed on the gauge surface 31. The gauge teeth 32 rotate circumferentially with the rotation of the drill bit to cut the well wall to keep the well wall smooth and regular. Preferably, the multiple gauge teeth 32 in the gauge structure 30 are distributed in an inclined straight line as a whole, such as Figure 2 and Figure 4 As shown, at least two gauge teeth 32 include a first gauge tooth 321 and a second gauge tooth 322, and the angle between the line connecting the end face center of the first gauge tooth 321 and the end face center of the second gauge tooth 322 and the axis of the PDC drill bit is 45°, which is used to cut and trim the well wall at different depths. Furthermore, the gauge structure 30 of the core blade 10 is the same as the gauge structure 30 of the outer cone blade 20, that is, in each gauge structure 30, the distribution of the gauge teeth 32 is the same, which is conducive to the contact between the gauge teeth 32 and the well wall, increasing the contact area and reducing the well deviation.

[0056] Furthermore, the gauge surface 31 is provided with an alloy column groove, and the gauge teeth 32 are inserted into the alloy column groove with interference fit. Preferably, the outside of the gauge teeth 32 is reinforced with protection by a surfacing process to enhance its wear resistance and impact resistance.

[0057] The front end surface of the drill crown 71 of the PDC drill bit is provided with a nozzle 60; preferably, please refer to Figure 2 The number of nozzles 60 is 6, which speeds up the discharge of rock cuttings, enhances the cooling and cleaning of the composite sheet cutting teeth 40, and avoids repeated cutting of rock cuttings at the bottom of the well, thereby improving the cutting efficiency. Auxiliary cutting teeth 50 are respectively provided on the first cutting surface 110 and the second cutting surface 210.

[0058] In one embodiment of the present invention, the drill crown 71 is made of an integral alloy structural steel by machining equipment such as a lathe, a milling machine, etc. A threaded structure is provided at the lower end of the drill crown 71, and the drill crown 71 is connected to the joint structure 72 by a threaded connection, and a welding process is used to strengthen the connection to ensure torque resistance.

[0059] The above are only several embodiments of the present invention. Those skilled in the art may make various changes or modifications to the embodiments of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A PDC drill bit, characterized in that: include: Core blades and outer cone blades are distributed around the circumference of the PDC drill bit, the core blades are provided with a diameter protection structure and a core mounting surface with a composite piece cutting tooth installed, and the outer cone blades are provided with a diameter protection structure and an outer cone mounting surface with a composite piece cutting tooth installed; The maximum outer diameter R of the outer contour of the core mounting surface max , and the minimum outer diameter R of the inner contour of the outer cone mounting surface min satisfy: R max ≤(0.9·R 保径 ), And R min ≥(0.3·R 保径 ); On the end face projection of the PDC drill bit, the first reference point and the second reference point of the composite piece cutting tooth on the outer cone blade are both located within the range defined by the outer cone mounting surface; the first reference point and the second reference point of the composite piece cutting tooth on the core blade are both located within the range defined by the core mounting surface; The core blade is provided with a blade groove, and the blade groove is located outside the core mounting surface; the blade groove defines the outer contour of the core mounting surface.

2. The PDC drill bit according to claim 1, characterized in that: The diameter-preserving structure of the core blade is the same as the diameter-preserving structure of the outer cone blade.

3. The PDC drill bit according to claim 1, characterized in that: The gauge protection structure comprises a gauge surface and at least two gauge protection teeth fixed on the gauge surface.

4. The PDC drill bit according to claim 3, characterized in that: The gauge surface is provided with an alloy column groove, and the gauge teeth are embedded in the alloy column groove with interference fit.

5. The PDC drill bit according to claim 1, characterized in that: The PDC drill bit comprises three core blades and three outer cone blades, and the core blades and the outer cone blades are alternately distributed in sequence around the circumference of the PDC drill bit.

6. The PDC drill bit according to claim 5, characterized in that: Each of the outer conical blades is provided with three of the composite sheet cutting teeth; The three core blades include a first core blade, a second core blade and a third core blade which are distributed in sequence. The first core blade is provided with two composite sheet cutting teeth, and the second core blade and the third core blade are provided with three composite sheet cutting teeth.

7. The PDC drill bit according to claim 1, characterized in that: The core blade has a first cutting surface and a first back cutting surface located on both sides of the core mounting surface, and the first cutting surface and the first back cutting surface are arranged obliquely relative to the axis of the PDC drill bit.

8. The PDC drill bit according to claim 7, characterized in that: The outer cone blade has a second cutting surface and a second back cutting surface located on both sides of the outer cone mounting surface, and the second cutting surface and the second back cutting surface are inclined relative to the axis of the PDC drill bit.

9. The PDC drill bit according to claim 1, characterized in that: A nozzle is arranged on the front end surface of the drill crown of the PDC drill bit.

10. The PDC drill bit according to claim 9, characterized in that: The number of the nozzles is 6.

11. The PDC drill bit according to claim 8, characterized in that: Auxiliary cutting teeth are respectively arranged on the first cutting surface and the second cutting surface.

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