JP6468507B2 - PDC cutter for well drilling and PDC bit for well drilling - Google Patents

Description

  The present invention relates to a well drilling PDC cutter that is attached to a well drilling bit and used to mine oil, natural gas, geothermal fluid, and the like, and a well drilling PDC to which the well drilling PDC cutter is attached. It is about bits.

  In the mining of oil and natural gas, a PDC bit using a sintered body (Polycrystalline Diamond Compact, referred to as PDC), which was developed in the 1970s, as a cutter. The drilling tool called is popular. The reason is that a PDC bit having a disc-like PDC cutter 3 composed of a PCD layer 1 and a cemented carbide (WC-Co) layer 2 as shown in FIG. This is because it contributes to the improvement of sex. According to Non-Patent Document 1, the total drilling length of PDC bits in 2010 is reported to account for 65% of the total drilling length of wells drilled for oil and natural gas development. 35% of the total excavation length is excavated using a roller cone bit.

  A PDC cutter is generally formed by laminating fine single-crystal artificial diamond particles of about several tens of microns and tungsten carbide containing powdery cobalt, at a temperature of 1500 to 1600 ° C., and a pressure of 50 to 60,000 atmospheres. Sintered under high temperature and high pressure. During sintering, cobalt functions as a catalyst, so that a bond between diamond particles occurs and a polycrystalline PDC cutter having a large size can be manufactured.

  The thickness t3 of a general PDC cutter 3 as shown in FIG. 21 is about 3.5 mm, the thickness t1 of the PCD layer 1 is about 0.5 to 1.0 mm, and the thickness t2 of the cemented carbide layer 2 is The diameter of the PDC cutter 3 is about 8 to 50 mm. As shown in the cross-sectional view of FIG. 22, the PCD layer 1 and the cemented carbide layer 2 are generally joined in a plane. However, as shown in FIG. A technique for preventing peeling of the PCD layer 1 from the hard alloy layer 2 has also been developed (see, for example, Patent Document 1).

  The PDC bit is manufactured by brazing and joining a required number of PDC cutters 3 to the bit body. As shown in FIG. 24, a pocket 5 having the same shape as the PDC cutter 3 is formed at the tip of the bit body 4, and the back surface of the pocket 5 and the cemented carbide layer 2 on the back surface of the PDC cutter 3 are formed. Joined by brazing material. The PDC bit in which the PDC cutter 3 is joined to the bit body 4 in this manner is sent around the axial direction front end side (lower side in FIG. 24) while being rotated around its central axis, and depends on the rotational force and the thrust toward the front end side. The rock 6 is destroyed by the cutting action and the well is excavated. 24 indicates the rotation direction (cutting direction) of the PDC cutter 3 by the rotation of the bit body 4.

  Here, with reference to FIG. 25, the cutting manner of the rock 6 by such a PDC cutter 3 will be described. In the PDC cutter 3, the disk surface that faces the rotation direction T and becomes the rake face 7 of the cutting action, The PCD layer 1 includes the portion that becomes the cutting edge 9 of the cutting action of the intersecting ridge line portion with the outer peripheral surface that becomes the flank 8, and the rock 6 is cut and destroyed by the PCD layer 1 having excellent wear resistance. To do. On the other hand, the back surface of the PDC cutter 3 joined to the bit body 4 is supported by the cemented carbide layer 2 excellent in impact resistance, and the PDC cutter 3 is not easily broken or damaged. Yes. Furthermore, the characteristics of the PDC cutter 3 include that it is possible to provide a blade having a large size and that there is no cleaving, which is a defect of the single crystal diamond.

  Such a PDC bit with the PDC cutter 3 as a blade is widely used in oil fields and gas fields with a relatively soft and homogeneous formation, and as described above, greatly contributes to improving the efficiency of drilling and reducing costs. Yes. However, in the excavation of hard and heterogeneous formations, there is a problem that the PDC cutter 3 is damaged or worn.

  The problem of this PDC cutter will be explained. As shown in an enlarged view in FIG. 25, generally, in the cutting of the rock 6 by the PDC cutter 3 in which the rake face 7 and the flank face 8 intersect at a right angle at the cutting edge 9. In order to reduce the cutting resistance acting on the flank 8 and efficiently excavate the rock 6, a rake angle α is set on the rake face 7. As this rake angle α, a cutting resistance of about −10 to −15 ° is adopted (for example, see Non-Patent Document 2). At this time, a clearance angle β of 10 to 15 ° is generated on the clearance surface 8.

  If the rock 6 is cut in this state, the PCD layer 1 near the cutting edge 9 at the tip of the rake face 7 has a cutting force component force, as shown by the arrow in FIG. And a horizontal force H acting at right angles to the vertical force V toward the rear side in the rotational direction T acts. As described above, the PCD layer 1 is supported by the cemented carbide layer 2 in the direction perpendicular to the rake face 7, but the rake angle α is provided on the PCD layer 1 near the cutting edge 9 at the tip of the rake face 7. As shown in FIG. 25, a portion that is not supported by the cemented carbide layer 2 occurs in the direction in which the horizontal force H acts.

  When the rock 6 becomes hard, the vertical force V and the horizontal force H acting on the cutting edge 9 increase, so that a large shearing force acts on the PCD layer 1 in the vicinity of the cutting edge 9 at the tip and is supported by the cemented carbide layer 2. Defects in the PCD layer 1 called chipping are likely to occur in the portions that are not formed. Once chipping occurs in the PCD layer 1, wear begins to expand from this portion.

  As shown in FIG. 26, when the wear of the PCD layer 1 progresses and the wear surface 10 begins to spread, a load (thrust) for pressing and feeding the PDC cutter 3 into the rock 6 to maintain the same excavation speed. P must be increased. The increase in the load P increases the normal force V acting on the wear surface 10 of the flank 8, thereby increasing the frictional resistance acting on the wear surface 10, and as a result, a vicious circle in which the wear surface 10 rapidly expands. Arise. In particular, when the wear surface 10 extends to the cemented carbide layer 2, the load P must be further increased, and the PDC cutter 3 and the PDC bit reach their lifetime without delay. According to Non-Patent Document 3, the dynamic friction coefficient of the wear surface 10 of the flank 8 in cutting of the rock 6 is as large as about 0.6, but no means for effectively reducing the frictional resistance of the wear surface 10 has been found. .

US Pat. No. 8,297,382

Federico Bellin et al .: The current state of PDC bit thchnology, World Oil, Sept., 2010, p.41-46. Kazuzawa Karasawa and two others, “Influence of Rake Angle on Performance of PDC Bit”, Journal of Resources and Materials, 107 (1991) No. 12 pp. 853-858 Hirohide Hayami and three others "Influence of wear resistance on rock cutting" Journal of the Japan Mining Association / 91 1044 (1975-2) pp. 55-59

  The present invention has been made under such a background, and a PDC cutter for drilling a well and a PDC bit for drilling a well that are not easily damaged or worn when used for drilling a well in a hard and heterogeneous formation. In order to improve drilling efficiency and reduce costs not only for soft rock excavation, which is the application range of conventional well drilling PDC cutters and well drilling PDC bits, but also for hard rock drilling Yes.

In order to solve the above-described problems and achieve such an object, the PDC cutter for well excavation of the present invention is attached to the tip of the bit body rotated around the axis, and the rotational force of the bit body And a well drilling PDC cutter for drilling a well by a cutting action by the thrust toward the tip end in the axial direction, comprising a cutter body having at least a polycrystalline diamond (PCD) layer and a cemented carbide layer, The cutter body is formed in a disc shape, the circular surface of which is a rake face directed in the rotation direction of the bit body , and the outer peripheral surface is a flank face, and the ridge line between the rake face and the flank face parts in which the cutting edge on the circumference of the circular surface is formed, the polycrystalline diamond layer, so as to expose the entire outer peripheral surface of the cutter body, the cutter body comprising said cutting edge Together is arranged in the region of the lower surface side, the cemented carbide layer is characterized by being arranged in the inner area than the polycrystalline diamond layer in the rake face of the cutting body.

  Further, the PDC bit for well excavation of the present invention has the rake face of the cutter main body at the tip of the bit main body rotated around the axis of the well excavation PDC cutter of the present invention having the above-described configuration. The bit body is oriented in the rotational direction, and the flank of the cutter body is attached toward the tip end side in the axial direction.

  In the PDC cutter for well excavation of the present invention, the PCD layer (polycrystalline diamond layer) is disposed in the flank side region including the cutting edge of the cutter body, and the cemented carbide layer is more than the PCD layer. Since the PDC bit of the present invention in which such a PDC cutter is attached as described above is disposed in the region inside the rake face of the cutter body, it extends along the circumferential direction of the bit body from the tip of the cutting blade. In the cross section of the cutter body, the PCD layer in the flank area is disposed so as to extend in a direction opposite to the axial direction of the bit body, and the cemented carbide layer in the inner area of the rake face on the rear end side of the PCD layer Will be disposed.

  In other words, since the PCD layer and the cemented carbide layer of the cutter body are stacked in the direction in which the vertical force acts near the cutting edge at the tip of the rake face, the PDC cutter is made to rock by rock surface wear. Even if the load (thrust) for press-fitting is increased, the expansion of the wear surface due to the vertical force accompanying the increase in the load can be suppressed by the PCD layer having excellent wear resistance. In addition, the impact caused by the increased normal force can be absorbed by the cemented carbide layer disposed on the axial rear end side of the PCD layer, so that it is possible to suppress damage and chipping of the PCD layer near the cutting edge. In addition, since the area of the PCD layer occupying the flank can be increased, the wear of the flank itself can be suppressed.

  Here, an intermediate layer between the PCD layer and the cemented carbide layer may be disposed between the PCD layer and the cemented carbide layer. By interposing such an intermediate layer with a mixture of PCD and cemented carbide between the PCD layer and the cemented carbide layer, it is possible to more reliably alleviate the impact caused by the normal force and at the same time wear intermediate. Even if it reaches the layer, the progress can be suppressed.

  Further, the PCD layer and the cemented carbide layer, or the PCD layer and the intermediate portion are formed by making the boundary portion on the cemented carbide layer side of the PCD layer, particularly the boundary portion inside the rake face of the PCD layer, into a curved shape. It is possible to prevent the PCD layer from peeling off by increasing the bonding area with the layer. The curved surface in this case may be a curved surface that bends in the direction along the cutting edge, and further increases the bonding strength by ensuring a larger bonding area as a curved surface that is wave-shaped as shown in FIG. You may make it raise.

Further, in the present invention, the cutter body is formed in a disc shape, the disc surface is used as the rake face, the cutting blade is formed on the circumference of the disc surface, and the PCD layer is formed by the cutter. By arranging it so as to be exposed on the entire outer peripheral surface of the main body, for example, when the cemented carbide layer part is joined by brazing and the cutter main body is attached to the bit main body, the cutting blade positioned on the bit body tip side When wear or the like occurs in the cutter body, the brazed joint surface is heated so that the sharp cutting blade portion that is not worn is reattached so that it is located on the tip side of the bit body, so that the cutter body can be effectively used. .

  When the cemented carbide layer portion of the cutter body is brazed and attached to the bit body in this way, it is desirable to join the bit body with a brazing material having a melting point of 700 ° C. or less, and thereby heating during brazing. Therefore, it can be avoided that the polycrystalline diamond of the PCD layer is carbonized.

  On the other hand, by forming the flank of the cutter body so as to form a convex curved surface that curves in a direction away from the cutting edge, the rake angle is small while giving a predetermined flank to the flank. It is possible to reduce the resistance acting on the cutter main body when cutting the rock. In this case, in particular, the PCD layer is also formed in a layer shape that curves in a direction away from the cutting edge, so that the horizontal force of the PCD layer near the cutting edge at the tip of the rake face is reduced. Since the thickness in the acting direction can be increased, it is possible to more reliably prevent the PCD layer near the cutting edge from being damaged or chipped.

  As described above, according to the present invention, even if the load for press-fitting the PDC cutter into the rock is increased, the expansion of the wear surface can be suppressed, and the excavation efficiency is improved even in a hard and heterogeneous formation. The cost required for excavation can be reduced by extending the life of the PDC cutter.

It is the front view seen from the direction which opposes a rake face which shows a 1st embodiment of a PDC cutter of the present invention. It is a side view of embodiment shown in FIG. It is ZZ sectional drawing in FIG. It is a front view which shows 1st Embodiment of the PDC cutter of this invention which attached the PDC cutter of 1st Embodiment shown in FIG. It is sectional drawing of the front-end | tip part of embodiment shown in FIG. It is sectional drawing which shows the case where it excavates with the PDC cutter attached to embodiment shown in FIG. It is a front view which shows 2nd Embodiment of the PDC cutter of this invention which attached the PDC cutter of 1st Embodiment shown in FIG. It is sectional drawing of the front-end | tip part of embodiment shown in FIG. It is the front view seen from the direction which opposes a rake face which shows 2nd Embodiment of the PDC cutter of this invention. FIG. 10 is a side view of the embodiment shown in FIG. 9. It is ZZ sectional drawing in FIG. It is sectional drawing which shows an example in the case of excavating with the PDC cutter of embodiment shown in FIG. It is sectional drawing which shows another example at the time of excavating with the PDC cutter of embodiment shown in FIG. It is a side view which shows the 1st reference example with respect to embodiment of the PDC cutter of this invention. It is the front view seen from the direction which opposes a rake face which shows the 2nd reference example with respect to embodiment of the PDC cutter of this invention. It is a side view of the reference example shown in FIG. It is ZZ sectional drawing in FIG. It is a side view which shows the 3rd reference example with respect to embodiment of the PDC cutter of this invention. It is a side view which shows the 4th reference example with respect to embodiment of the PDC cutter of this invention. It is the front view seen from the direction which opposes a rake face which shows the 5th reference example with respect to embodiment of the PDC cutter of this invention. It is a perspective view which shows the conventional PDC cutter. It is sectional drawing of the PDC cutter shown in FIG. It is sectional drawing which shows the other conventional PDC cutter. It is sectional drawing which shows an example in the case of excavating with the PDC cutter shown in FIG. It is an expanded sectional view of the front-end | tip part of a cutting blade in the case of excavating with the PDC cutter shown in FIG. It is an expanded sectional view of the front-end | tip part of a cutting blade which shows the case where wear advances from the state shown in FIG.

  FIGS. 1 to 3 show a first embodiment of a PDC cutter for well excavation according to the present invention. FIGS. 4 to 6 show the PDC cutter according to the first embodiment to which the PDC cutter according to the first embodiment is attached. 1 shows a first embodiment of a well drilling PDC bit. In the PDC cutter of this embodiment, the cutter body 11 has a disk shape, a first circular surface that is a rake surface 12, an outer peripheral surface that is a flank surface 13, and a joint surface 14 to a PDC bit. A cutting edge 15 having a circumferential convex curve is formed on the outer peripheral edge of the first circular surface, which is a crossing ridge line portion between the rake surface 12 and the flank surface 13. ing. In the present embodiment, the outer peripheral surface that is the flank 13 is a cylindrical surface having a constant outer diameter, and intersects the first circular surface that is the rake surface 12 at a right angle at the cutting edge 15. The second circular surface which is the joining surface 14 also intersects at a right angle.

  The PDC cutter includes at least a PCD layer 16 made of a polycrystalline diamond sintered body and a cemented carbide layer 17 made of a cemented carbide such as WC-Co. Among these, the PCD layer 16 has a cutting edge. The cemented carbide layer 17 is disposed in a region on the inner side of the rake face 12 than the PCD layer 16. That is, the PCD layer 16 is exposed to a region on the rake face 12 side where at least the cutting edge 15 of the flank 13 of the cutter body 11 is formed, and an area within a predetermined range from the cutting edge 15 to the inside of the rake face 12. The cemented carbide layer 17 is exposed in a region inside the PCD layer 16 on the rake face 12.

  In the present embodiment, the PCD layer 16 is exposed to the entire outer peripheral surface of the cutter body 11 serving as the flank 13 and has a substantially constant thickness from the outer peripheral surface to the radially inner peripheral side of the cutter body 11. The first circular surface, which is a cylindrical shape and therefore the rake surface 12, is arranged in an annular shape with a substantially constant width from the cutting edge 15 to the inner peripheral side, and is a second circular surface which is a joining surface 14. The circular surface of the PCD layer 16 is annularly arranged with the same constant width as the rake face 12 from the outer peripheral edge thereof, and the boundary portion on the cemented carbide layer 17 side of the PCD layer 16 is a cylindrical curved surface. Further, the cemented carbide layer 17 has a disk shape and is disposed coaxially inside the PCD layer 16.

  In the present embodiment, an intermediate layer 18 between the PCD layer 16 and the cemented carbide layer 17 is disposed between the PCD layer 16 and the cemented carbide layer 17. That is, the intermediate layer 18 includes both diamond particles of the PCD layer 16 and cemented carbide particles such as WC of the cemented carbide layer 17, and these particles are bonded by a metal binder such as Co. . The intermediate layer 18 is also formed in a cylindrical shape coaxial with the PCD layer 16 and the cemented carbide layer 17 in the present embodiment, and the PCD layer 16, the cemented carbide layer 17 and the intermediate layer 18 are formed at a high temperature and high pressure as described above. The cutter main body 11 of this embodiment is manufactured by sintering integrally below.

  Further, in the present embodiment, the intermediate layer 18 is composed of first and second intermediate layers 18A and 18B. In the plurality of intermediate layers 18A and 18B, the mass ratio of contained diamond particles and cemented carbide particles, the particle size (diameter range) of diamond particles and cemented carbide particles, the addition ratio of metal binder (100 × (metal Binder mass) / (diamond particle mass + carbide alloy mass)), at least one of the composition and thickness of the metal binder is different from each other or from the PCD layer 16 and the cemented carbide layer 17. . In this embodiment, the first intermediate layer 18A on the PCD layer 16 side has a larger mass ratio of diamond particles to cemented carbide particles than the second intermediate layer on the cemented carbide layer 17 side, that is, the PCD content is high. It is increasing. The intermediate layer 18 may be three or more layers, may be a single layer, or the intermediate layer 18 may not be provided.

  The cutter main body 11 of the PDC cutter according to the first embodiment configured as described above is attached to the distal end portion of the bit main body 21 as shown in FIGS. 4 to 6 and is the PDC bit according to the first embodiment of the present invention. And is used for well drilling. The bit body 21 is formed of a metal such as steel and has an outer shape that is generally cylindrical or disk-shaped. The PDC bit according to the present embodiment has a predetermined rotational direction around an axis O passing through the center of the cylinder or disk. While being rotated by T, it is sent to the tip end side in the axis O direction (the lower side in FIGS. 5 and 6) and moved forward, thereby causing the rotational force around the axis O and the thrust toward the tip end side in the axis O direction. The rock is broken by the cutting action of the cutting edge 15 of the PDC cutter to perform excavation.

In the central portion of the front end surface of the bit body 21, a recess 22 is formed which has a concave conical shape centering on the axis O and is recessed from the outer peripheral portion of the front end surface to the rear end side. A nozzle 23 is open, and a fluid such as compressed air or water is ejected from the nozzle 23 during excavation, whereby the broken rock is discharged from the well. Further, on the tip surface of the bit body 21 including the recess 22, the tip portion of the bit body 21 swells in a ¼ spherical shape or a vertically-divided shell shape, and the plane portion is directed in the rotation direction T. In addition, a plurality of convex portions 24 whose curved surface portions are directed rearward in the rotation direction T are formed, and pockets (recess portions) recessed from the front end surface of the bit body 21 on the rotation direction T side of the planar portions of these convex portions 24 ) 25 are formed.
The shape of the bit body shown in FIG. 5 is concave, but it may be flat or convex.

  A back surface 25A facing the rotation direction T of the pocket 25 extending from the flat surface portion of the convex portion 24 is a circular flat surface having the same size as the joining surface 14 of the cutter body 11, and rotates toward the rear end side in the axis O direction. It inclines so that it may go to the direction T side. In the pocket 25, the cutter body 11 of the PDC cutter according to the first embodiment is brazed to the back surface 25 </ b> A with the cemented carbide layer 17 exposed on the joining surface 14, so that one of the cutting edges 15. A portion (for example, 1/2 of the circle formed by the cutting blade 15) is protruded from the distal end surface of the bit body 21 including the recess 22, and the rake face 12 is directed in the rotational direction T and the relief connected to the protruding cutting blade 15 is provided. The surface 13 is attached toward the front end side in the axis O direction.

  Here, since the back surface 25A is inclined as described above, the rake face 12 is also inclined toward the rotation direction T side toward the rear end side in the axis O direction, and is negative, for example, about −10 °. A rake angle (back rake angle) α is set on the rake face 12. Further, in the PDC cutter of the present embodiment in which the rake face 12 and the flank face 13 intersect at a right angle at the cutting edge 15, the flank face of the rake face 12 intersects at the tip of the axis O direction with a relief of about 10 °. The angle β is set. Furthermore, in the PDC bit of the present embodiment, the rake face 12 is inclined so as to go to the rear side in the rotational direction T as it goes to the outer peripheral side of the bit body 21, whereby the rake face 12 is shown in FIG. As described above, a negative side rake angle θ of about −10 ° is set.

  The plurality of convex portions 24 and pockets 25 and the cutter main body 11 of the PDC cutter attached to these pockets 25 are shifted in the circumferential direction and radial direction of the bit main body 21 while being spaced apart from each other, and the nozzle 23 It is arranged so as to avoid. The protruding cutting edges 15 of the plurality of cutter bodies 11 that are offset in this way are continuous in the radial direction in the rotation locus around the axis O of the bit body 21 as shown in FIG. The bottom of the is excavated uniformly.

  In the PDC cutter having the above-described configuration, the PCD layer 16 is disposed in a region on the flank 13 side including the cutting edge 15 of the cutter body 11, and the cemented carbide layer 17 is formed on the rake face 12 than the PCD layer 16. Such a PDC cutter is disposed in the inner region, and the rake face 12 is directed in the rotational direction T as described above, and the flank 13 connected to the protruding cutting edge 15 is directed toward the front end side in the axis O direction. In the attached PDC bit, as shown in FIG. 6, in the cross section of the cutter body 11 along the circumferential direction of the bit body 21 from the tip of the cutting edge 15, the PCD layer 16 in the region on the flank 13 side is in the axis O direction. The cemented carbide layer 17 is disposed on the rear side of the PCD layer 16 in the direction of the axis O, extending in the opposite direction.

  That is, unlike the conventional PDC bit shown in FIG. 25, the PCD layer 1 of the PDC cutter is arranged so as to be substantially along the direction in which the vertical force V acts during excavation. In the PDC cutter and the PDC bit, as shown in FIG. 6, the PCD layer 16 and the cemented carbide layer 17 are disposed so as to overlap each other in the direction in which the vertical force V acts. For this reason, even if the load (thrust) for press-fitting the PDC cutter into the rock 6 is increased when the flank 13 is worn, the wear surface is enlarged due to the increase in the vertical force V accompanying the increase in the load. It can be suppressed by the PCD layer 16 having excellent wear resistance.

  Even if the impact toward the rear end side in the direction of the axis O increases with the increase in the vertical force V, the axis O of the PCD layer 16 in the region on the flank 13 side in the PDC cutter and the PDC bit configured as described above. Since the shock-absorbing can be absorbed by disposing the cemented carbide layer 17 having excellent impact resistance on the rear end side in the direction, the PCD layer 16 near the cutting edge 15 can be prevented from being damaged or chipped. Furthermore, since the area of the PCD layer 16 occupying the flank 13 can be increased, for example, by disposing the PCD layer 16 over the entire flank 13 as in this embodiment, the wear of the flank 13 itself is also suppressed. be able to.

  Therefore, according to such a PDC cutter and a PDC bit, the wear resistance is excellent not only in conventional well drilling in a relatively soft and homogeneous formation, but also in hard rock excavation in a hard and heterogeneous formation. The cutting edge 15 formed on the PCD layer 16 can improve the excavation efficiency, and the excavation cost can be reduced by extending the life of the PDC cutter.

  In the present embodiment, an intermediate layer 18 between the PCD layer 16 and the cemented carbide layer 17 is disposed between the PCD layer 16 and the cemented carbide layer 17, that is, in the intermediate layer 18, While the PCD content is greater than the cemented carbide layer 17, the cemented carbide content is greater than the PCD layer 16. That is, since the intermediate layer 18 which is superior in impact resistance than the PCD layer 16 and superior in wear resistance than the cemented carbide layer 17 is interposed, the impact due to the above-described normal force V is more reliably mitigated. In addition, it is possible to suppress the progress even when the wear reaches the intermediate layer 18.

  Further, in the present embodiment, the boundary portion of the PCD layer 16 on the cemented carbide layer 17 side, that is, the boundary portion between the PCD layer 16 and the intermediate layer 18 is formed into a curved surface, for example, this boundary portion. Can prevent the PCD layer 16 from peeling off by increasing the bonding area between the PCD layer 16 and the intermediate layer 18 as compared with the case where the flat plate shape is perpendicular to the radial direction of the disk-shaped cutter body 11. it can. In addition, by making the boundary portion on the cemented carbide layer 17 side in the PCD layer 16 in this way, the boundary portion between the intermediate layer 18 and the cemented carbide layer 17 can also be curved, so the intermediate layer 18 It is also possible to prevent peeling from occurring. In addition, if such a boundary part is made into the curved surface shape which corrugates as shown, for example in FIG. 23, a joining area can be ensured still more and joining strength can be raised further. When there is no intermediate layer 18, the boundary between the PCD layer 16 and the cemented carbide layer 17 may be curved.

  Furthermore, in the PDC cutter of the first embodiment, the cutter body 11 is formed in a disc shape, the first circular surface is a rake surface 12, and the circle of the first circular surface is A cutting edge 15 is formed on the periphery, and the PCD layer 16 is disposed on the entire outer periphery of the cutter body 11. For this reason, when the cemented carbide layer 17 having the second circular surface, which is the bonding surface 14 as in the PDC bit of the first embodiment, is bonded to the bit body 21 by brazing, the tip side of the bit body 21 When the cutting edge 15 protruding to the end wears and has reached the end of its life, the joining surface 14 is heated to melt the brazing material and the cutter body 11 is removed, and the sharp cutting edge 15 that is not worn becomes a bit. The cutter body 11 can be rotated and reattached so as to be positioned at the distal end side of the body 21, and the cost can be further reduced by effectively using the cutter body 11.

  In addition, in the present embodiment, the outer peripheral surface serving as the flank 13 intersects the second circular surface serving as the joining surface 14 at a right angle, and the PCD layer 16 includes the outer peripheral surface, the second circular surface, and the second circular surface. The cemented carbide layer 17 is disposed in a region on the inner side of the second circular surface with respect to the PCD layer 16. In other words, the cutter main body 11 is symmetrical with the front and back reversed. Therefore, when the cutting edge 15 on the entire circumference of the first circular surface, which is the rake face 12, is worn, the cutter body 11 is also removed from the bit body 21, and the first and second circular surfaces are polished if necessary. After that, the second circular surface is used as the rake surface 12 and the first circular surface is attached to the bit body 21 as the joint surface 14 so that the circumference of the second circular surface is used as the cutting edge 15. Is more economical.

  When the cemented carbide layer 17 on the joint surface 14 of the cutter body 11 is brazed and attached to the bit body 21 in this way, the brazing material used for brazing preferably has a melting point of 700 ° C. or lower. If brazing is possible at such a melting point, it is possible to avoid carbonization of the polycrystalline diamond of the PCD layer 16 due to heating during brazing.

  Further, in the PDC bit of the first embodiment, the bit body 21 is formed in a columnar shape or a disc shape, and the PDC cutter of the first embodiment is attached to the tip surface thereof. 7 and FIG. 8, a so-called core bit or ring in which the bit body 21 has a cylindrical or annular shape, and the PDC cutter is attached to the front end surface thereof, as in the PDC bit of the second embodiment of the present invention shown in FIG. It may be a bit configuration. In the second embodiment, the same reference numerals are assigned to elements common to the first embodiment.

  In the PDC bit of the second embodiment, the cutter main body 11 is alternately attached to the front end surface of the annular bit main body 21 on the outer peripheral side and the inner peripheral side of the front end surface in the circumferential direction of the bit main body 21. . As in the first embodiment, a negative side rake angle θ of about −10 ° is set on the rake face 12 of the cutter main body 11 attached to the outer peripheral side, and the rake of the cutter main body 11 attached to the inner peripheral side is set. A negative side rake angle θ of about −10 ° is also set on the surface 12. As shown in FIG. 8, the inner and outer cutter main bodies 11 also have radial cutting edges 15 that protrude toward the front end side of the bit main body 21 in the rotation locus around the axis O.

  Next, FIG. 9 thru | or FIG. 11 shows 2nd Embodiment of the PDC cutter of this invention, PDC of 3rd thru | or 7th embodiment described after this 2nd embodiment first. Also in a cutter, the same code | symbol is distribute | arranged to the element which is common in the PDC cutter of 1st Embodiment.

  In the PDC cutter of the first embodiment, the first and second outer surfaces, which are the flank 13 of the disk-shaped cutter body 11, have a constant outer diameter, and are the rake face 12 and the joining face 14. In the PDC cutter according to the second embodiment, the outer peripheral surface that is the flank 13 of the disc-shaped cutter body 11 is the rake face 12, whereas it intersects the circular face at a right angle. Formed so as to form a convex curved surface such as a cross-sectional arc that curves in a direction away from the cutting edge 15 formed in the intersecting ridge line portion with the circular surface (the direction from right to left in FIGS. 10 and 11). It is characterized by being. Here, the flank 13 in the second embodiment is formed so as to gradually decrease in outer diameter while being curved in a direction away from the cutting edge, and thus is the first joint surface 14. The second circular surface has a smaller diameter than the first circular surface which is the rake face 12.

  Further, in the second embodiment, as the flank 13 is curved in this way, the PCD layer 16 exposed to the flank 13 and the intermediate layer 18 (first, The second intermediate layers 18A, 18B) and the outer peripheral side boundary portion of the inner cemented carbide layer 17 are also formed in a layered shape that curves in the direction away from the cutting edge 15 as shown in FIG. The diameter is gradually reduced. However, in the second embodiment, the thicknesses of the PCD layer 16 and the intermediate layer 18 are substantially constant.

  FIG. 12 shows an example when the PDC cutter according to the second embodiment is attached to a PDC bit. In the PDC cutter according to the second embodiment, the flank 13 is cut as described above. Since it has a convex curved surface shape that curves in a direction away from the blade 15 and the outer diameter is made gradually smaller, the rake angle α of the rake face 12 is set to the first rake angle α as shown in FIG. Even if the absolute value is set smaller than that of the embodiment, a certain clearance angle β can be given to the clearance surface 13. In FIG. 12, the rake angle α is set to 0 °. Further, the cutter body 11 is attached to the PDC bit by brazing the cemented carbide layer 17 exposed on the joint surface 14 as in the first embodiment.

  Therefore, in the PDC cutter of the second embodiment and the PDC bit to which the PDC cutter is attached, the rake angle α can be reduced, so that the resistance acting when cutting the rock 6 can be reduced. it can. For this reason, the wear of the PDC cutter can be further suppressed, and the cost can be reduced by further extending the service life. The crossing angle between the rake face 12 and the flank face 13 in the cutting edge 15 may be a right angle or an acute angle as in the first embodiment, but even if it is an acute angle, the PDC of the present invention. As described above, the cutter destroys the rock 6 by the cutting action, and the loading and unloading of the vertical force (load) is not repeatedly performed like a tip attached to a roller cone bit or a percussion bit, for example. Therefore, generation | occurrence | production of a defect | deletion and chipping can be suppressed.

  In the second embodiment, the PCD layer 16 exposed on the flank 13 is also bent in a direction away from the cutting edge 15 in addition to the flank 13 being bent in this way. Therefore, similar to the conventional PDC cutter and the PDC cutter of the first embodiment, even when the negative rake angle α is set on the rake face 12 as shown in FIG. Compared with the PDC cutter of one embodiment, the thickness Wn of the PCD layer 16 in the direction in which the horizontal force acts near the cutting edge 15 at the tip of the rake face 12 can be increased. For this reason, the PCD layer 16 in the vicinity of the cutting edge 15 can be firmly supported from the back side, and the breakage and chipping can be more reliably prevented, and the wear of the flank 13 is more effective. Can be suppressed.

  Further, in the second embodiment, the boundary portion on the cemented carbide layer 17 side in the PCD layer 16 is formed in a curved surface curved along the cutting edge 15 as in the first embodiment. Thus, since the curved surface is curved in the direction away from the cutting edge 15, it is possible to further secure the bonding area with the intermediate layer 18 and further prevent the PCD layer 16 from peeling off. The same applies to the boundary portion between the intermediate layer 18 and the cemented carbide layer 17.

By the way, in the PDC cutters of the first and second embodiments, the cutter main body 11 is formed in a disc shape, and the cemented carbide layer 17 exposed on the first circular surface which is the joining surface 14 is brazed. In contrast to this, in the first reference example for the embodiment of the present invention shown in the side view in FIG. 14, the cutter body 11 is formed in a substantially hemispherical shape or the like. The back surface forming a convex curved surface such as a spherical surface is a cemented carbide layer 17, and the cutter body 11 is attached to the PDC bit by brazing the cemented carbide layer 17 on the back surface as a joining surface 14. Yes.

Here, in the first reference example, the PCD layer 16, the cemented carbide layer 17, and the intermediate layer on the side of the circular surface (the first circular surface in the first and second embodiments) that is the rake face 12. The configuration of 18 is the same as that of the second embodiment. Further, in the bit body 21 of the PDC bit to which such a PDC cutter is attached, the back surface 25A of the pocket 25 to which the cemented carbide layer 17 of the joint surface 14 is joined is a spherical surface formed by the back surface of the cutter body 11 or the like. The convex curved surface is formed into a concave curved surface that can be closely attached.

Therefore, according to the PDC cutter of the first reference example , the bonding area between the bonding surface 14 and the bit body 21 can be secured larger than the PDC cutter of the first and second embodiments. It becomes possible to improve the bonding strength .

15 to 17 show a second reference example for the embodiment of the PDC cutter of the present invention. In the first, second and first reference examples , the rake face 12 is a circular surface. have been a, whereas PCD layer 16 and intermediate layer 18 has been disposed substantially constant thickness in the radial direction of the circular surface, starting with the second reference example, 18 to 20 In the third to fifth reference examples shown in FIG. 15, the rake face 12 is an oval surface as shown in FIG. 15 (however, in FIG. 15, an ellipse halved in the major axis direction) or as shown in FIG. Such an elliptical surface (however, in FIG. 20, an ellipse that is halved in the major axis direction), the side ridge portion forming the convex curve is the cutting edge 15, and the cutting edge 15 extends in the extending direction. The PCD layer 16 and the intermediate layer 18 have different thicknesses.

Specifically, in the second to fourth reference examples , the cutting edge 15 has a semicircular shape as shown in FIG. 15, and the PCD layer 16 and the intermediate layer exposed at the rake face 12 at the center of this semicircle. The thickness of the layer 18 (first and second intermediate layers 18A and 18B) is the largest, and gradually decreases toward both ends of the cutting edge 15. In the fifth reference example , the cutting edge 15 has a semi-elliptical shape as shown in FIG. 20, and the PCD layer 16 and the intermediate layer 18 are also thickest at the center of the semi-ellipse, and as they approach both ends. It is getting thinner gradually.

In the second to fourth reference example, the flank 13 as shown in FIGS. 16 to 19 as in the second embodiment and the first reference example, in a direction away from the cutting edge 15 projecting It is formed in a convex curved surface shape such as a curved spherical surface. Also in the direction away from the cutting edge 15 along the flank 13, the thicknesses of the PCD layer 16 and the intermediate layer 18 (first and second intermediate layers 18A and 18B) as shown in the cross-sectional view of FIG. Is the thickest on the side of the cutting edge 15 and gradually becomes thinner as the distance from the cutting edge 15 increases.

In the second to fifth reference examples , the side surface 19 of the cutter body 11 made of the cemented carbide layer 17 on the side opposite to the cutting edge 15 is a flat surface perpendicular to the rake surface 12. The cemented carbide layer 17 exposed on the back surface of the cutter body 11 and the cemented carbide layer 17 exposed on the side surface 20 extending from both ends of the side surface 19 to both ends of the cutting blade 15 are brazed and attached to the PDC bit. Here, the length L of the cemented carbide layer 17 portion on the rake face 12 in the direction perpendicular to the central portion of the cutting edge 15 from the side face 19 shown in FIG. 15 is arbitrarily set according to the shape of the bit body 21. Can be set.

In such second to fifth reference examples , when the PCD layer 16 is attached to the PDC bit, the PCD layer 16 has a thickness at the central portion of the cutting blade 15 that protrudes most toward the tip side and is used for rock cutting. Since it is the thickest, chipping and chipping can be effectively prevented while making effective use of expensive PCD. Further, by increasing the length L, the side 20 and the cemented carbide layer 17 on the back side can be enlarged as shown by the broken lines in FIGS. Therefore, the cutter body 11 and the bit body 21 can be more firmly joined.

In the third reference example shown in FIG. 18, a convex curved surface portion such as a spherical surface made of a cemented carbide layer 17 is formed on the back surface of the cutter body 11 on the back side of the cutting blade 15 as in the first reference example. Is formed. Further, in the fourth reference example shown in FIG. 19, a part of the cemented carbide layer 17 on the back surface of the third reference example is cut away in parallel to the rake face 12, so that the flat joining surface 14 on the back surface is formed. It has been enlarged. In the third and fourth reference examples , the size and shape of the pockets of the bit body 21 are formed in accordance with the exposed cemented carbide layer 17, so that the bonding area is larger than that of the second reference example. Can be secured.

  Next, examples of the PCD layer and the intermediate layer of the PDC cutter of the present invention will be described. In this example, the number of intermediate layers, the mass ratio of contained diamond particles and cemented carbide particles, the particle size (particle size range) and content of diamond particles and cemented carbide particles in the PCD layer and the intermediate layer. , Particle size and content of cemented carbide particles, composition of metal binder, addition ratio of metal binder (100 × (metal binder mass) / (diamond particle mass + carbide alloy mass)), and thickness of each layer Were set as shown in Tables 1-5.

  Table 1 shows the first embodiment. In this first embodiment, the intermediate layer is composed of three layers of first to third intermediate layers in order from the PCD layer to the cemented carbide layer, and the mass ratio of diamond particles to cemented carbide particles (WC particles) in this order. Is small, that is, the diamond particles contained are small and the cemented carbide particles are large. The third intermediate layer is thinner than the first and second intermediate layers.

  Table 2 shows the second embodiment. Also in the second embodiment, the intermediate layer is composed of the first to third intermediate layers in order from the PCD layer to the cemented carbide layer, and the mass ratio of the diamond particles to the cemented carbide particles (WC particles) in this order. And the size of the diamond particles contained is also reduced. The addition ratio of the metal binder (Co) increases from the PCD layer to the first to third intermediate layers, and the third intermediate layer is thinner than the first and second intermediate layers as in the first embodiment. ing.

  Table 3 shows the third embodiment. In this third embodiment, the diamond of the PCD layer is composed of two types of particle sizes. Further, the intermediate layer is a single layer composed of only the first intermediate layer, and the metal binder is Fe and Co in this intermediate layer. Further, the addition ratio of the metal binder is slightly higher in the intermediate layer than in the PCD layer.

  Table 4 shows the fourth embodiment. Also in the fourth embodiment, the diamond of the PCD layer is composed of two kinds of particle sizes as in the third embodiment, and the intermediate layer is a single layer of only the first intermediate layer. The metal binder is Co and Fe. In the fourth embodiment, the cemented carbide particles in the intermediate layer are made TaC, and the metal binder in the PCD layer is made Ni.

  Table 5 shows the fifth embodiment. In this fifth embodiment, the intermediate layer is composed of two layers of the first and second intermediate layers, and the PCD layer also contains cemented carbide particles (WC particles). The mass ratio of diamond particles and cemented carbide particles decreases in the order of the intermediate layer. In addition, the particle size of the contained diamond and WC is the same in each layer, and the addition ratio of the metal binder is also equal. However, the metal binder of the PCD layer is Co, and the metal binder of the intermediate layer is Fe and Co.

  As described above, the present invention is not limited to the development of oil and natural gas, etc., in a soft and homogeneous formation to which the conventional PDC cutter and PDC bit can be applied. It can also be used for oil and natural gas development in heterogeneous geological formations, geothermal development and mine development, and civil engineering and construction.

DESCRIPTION OF SYMBOLS 11 Cutter body 12 Rake face 13 Flank face 14 Joining face 15 Cutting edge 16 PCD layer 17 Cemented carbide layer 18 Intermediate layer 18A 1st intermediate layer 18B 2nd intermediate layer 19, 20 Side surface 21 Bit body 22 Recess 23 Nozzle 24 Convex Part 25 Pocket 25A Back of pocket 25 O Axis of bit body 21 T Rotation direction of bit body 21 α Rake angle (back rake angle)
β Clearance angle θ Side rake angle V Vertical force H Horizontal force P Load

Claims (8)

A well drilling PDC cutter, which is attached to the tip of a bit body rotated about an axis and drills a well by a cutting action by the rotational force of the bit body and thrust toward the tip of the axial direction. ,
Comprising a cutter body having at least a polycrystalline diamond layer and a cemented carbide layer;
The cutter body is formed in a disc shape, the circular surface of which is a rake face directed in the rotation direction of the bit body , and the outer peripheral surface is a flank face, and the ridge line between the rake face and the flank face A cutting blade is formed on the circumference of the circular surface that is a part ,
The polycrystalline diamond layer, so as to expose the entire outer peripheral surface of the cutter body, while being arranged in the region of the flank face side of the cutter body, including the cutting edge, the cemented carbide layer, the A PDC cutter for well excavation, wherein the PDC cutter is disposed in a region inside the polycrystalline diamond layer on the rake face of the cutter body .   The well drilling according to claim 1, wherein an intermediate layer between the polycrystalline diamond layer and the cemented carbide layer is disposed between the polycrystalline diamond layer and the cemented carbide layer. PDC cutter.   The PDC cutter for well excavation according to claim 1 or 2, wherein a boundary portion on the cemented carbide layer side in the polycrystalline diamond layer has a curved surface shape. The well according to any one of claims 1 to 3 , wherein the flank of the cutter body has a convex curved surface that curves in a direction away from the cutting edge. PDC cutter for excavation. 5. The well excavation according to claim 1 , wherein the polycrystalline diamond layer has a layered shape that curves in a direction away from the cutting edge. 6. PDC cutter. The PDC cutter for well excavation according to any one of claims 1 to 5 , wherein a rake face of the cutter body is disposed at a tip portion of the bit body rotated about an axis, and a rotation direction of the bit body A well drilling PDC bit, wherein the flank of the cutter body is attached to the tip end side in the axial direction. Claim the polycrystalline diamond layer in the cross section of said cutter body along the circumferential direction of the bit body from the tip of the cutting edge, characterized in that it is arranged so as to extend in a direction opposite to the axial direction 6. A PDC bit for well drilling according to 6 . The well body drilling PDC according to claim 6 or 7 , wherein the cutter body is attached to the bit body with a brazing metal having a melting point of 700 ° C or less. bit.

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