An impact shearing composite drill bit for hard formations

Abstract

The present invention provides an impact shear composite drill bit for hard formations, comprising: a drill body, a convex outer ring extending axially outward is provided on the lower end surface of the drill body; an impact device is arranged at the upper end of the drill body, the impact device comprises an outer shell, a driving mechanism, an impactor, and a pressure transmission mechanism arranged in the drill body in sequence from top to bottom, the pressure transmission mechanism comprises at least one punch penetrating the drill body, and an impact tooth is provided at the end of the punch, wherein the impact device is constructed to generate periodic impact loads under the action of the driving mechanism and the impactor, and transmit the loads to the impact teeth through the punch, so that the impact teeth generate periodic impact loads; the convex outer ring cuts an annular groove at the bottom of the well, and forms the bottom rock inside the convex outer ring into a core column with a dome-shaped top, and the impact tooth can cause pre-crushing and tensile splitting damage to the core column, so as to perform rock breaking construction.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas drilling tools, and in particular relates to an impact shearing composite drill bit for hard formations. Background Art

[0002] In oil and gas exploration and production projects, the drill bit is an indispensable downhole tool in rotary drilling construction, and the design and selection of the drill bit is a key component to improve the rock breaking efficiency in complex formations, increase the drilling speed and reduce the drilling cost.

[0003] The most commonly used drill bit in rotary drilling is the PDC drill bit, which mainly breaks rocks by cutting and shearing. However, for hard formations, the commonly used PDC drill bits still have some problems. For example, it is difficult for the PDC drill bit to penetrate the formation in hard formations, and the threshold values ​​of the drilling pressure and drill bit torque required for efficient rock breaking are high, even exceeding the working capacity of current equipment, drilling tools or downhole tools, resulting in low mechanical drilling speed in hard formations and low drilling efficiency. The PDC drill bit cannot penetrate the formation stably and cannot continuously and smoothly obtain the drill bit torque required for rock breaking. Downhole vibrations such as lateral vibration and torsional vibration will occur at the bottom of the well, which will induce vortex, stick-slip and other movements, which can easily cause early damage to the PDC drill bit and seriously shorten the service life of the drill bit. In addition, the closer to the center of the PDC drill bit, the lower the cutting torque and linear speed of the cutting teeth, the lower the cutting efficiency of the cutting teeth, and the core of the drill bit, that is, the rock in the center cannot be broken in time, and will also "hold up" the drill bit. On the one hand, this affects the mechanical drilling speed, and on the other hand, it will cause the drill bit to hollow out, which will also affect the service life of the drill bit. In hard formations and soft and hard staggered formations, the problems of slow mechanical drilling speed, short life, and low footage of the drill bit seriously affect the bottom hole drilling efficiency, extend the drilling cycle, and increase the drilling cost. In addition, in the prior art, in order to improve the use effect of the drill bit in hard formations, the commonly used method is to increase the number of drill blades and tooth density, reduce the size of the cutting teeth and other measures. Although these can increase the service life of the drill bit, they significantly reduce the mechanical drilling speed of the drill bit. Summary of the invention

[0004] In response to the technical problems mentioned above, the present invention aims to propose an impact shear composite drill bit for hard formations. The impact shear composite drill bit combines cutting and impact rock breaking functions, which can improve the ability to penetrate hard formations and reduce rock breaking energy consumption. It can significantly improve the mechanical drilling speed and ensure the stability of the impact shear composite drill bit, thereby greatly improving the rock breaking efficiency and effectively extending its service life.

[0005] To this end, the present invention provides an impact shear composite drill bit for hard formations, comprising: a drill body, a convex outer ring extending axially outward is provided on the lower end surface of the drill body; an impact device arranged at the upper end of the drill body, the impact device comprising an outer shell, a driving mechanism, an impactor, and a pressure transmission mechanism arranged in the drill body in sequence from top to bottom, the pressure transmission mechanism comprising at least one punch penetrating the drill body, and an impact tooth is provided at the end of the punch, wherein the impact device is configured to generate a periodic impact load under the action of the driving mechanism and the impactor, and transmit the load to the impact tooth through the punch, so that the impact tooth generates a periodic impact load; the convex outer ring cuts an annular groove at the bottom of the well, and forms the bottom rock inside the convex outer ring into a core column with a dome-shaped top, and the impact tooth can cause pre-crushing and tensile splitting damage to the core column, thereby performing rock breaking construction.

[0006] In one embodiment, the impactor includes an impact rod and a valve disc mechanism arranged at one end of the impact rod, the valve disc mechanism includes a static valve disc and a dynamic valve disc, the static valve disc is fixedly connected to the upper end of the impact rod, and the dynamic valve disc is configured to be driven to rotate by the driving mechanism under the action of drilling fluid, so that the flow area of ​​the valve disc mechanism changes periodically, so that the valve disc mechanism forms a periodically changing pressure and transmits it downward to the impact tooth through the impact rod.

[0007] In one embodiment, the driving mechanism includes a guide wheel and an impeller rotatably connected to the guide wheel, the impeller is fixedly connected to the movable valve disc, and the drilling fluid is diverted to the impeller under the action of the guide wheel and pushes the impeller to drive the movable valve disc to rotate.

[0008] In one embodiment, a first eccentric flow channel and a second eccentric flow channel are respectively provided on the movable valve disc and the stationary valve disc, and as the movable valve disc rotates, the flow area of ​​the valve disc mechanism changes periodically.

[0009] In one embodiment, the impactor also includes a return spring sleeved on the outer periphery of the impact rod, one end of the return spring abuts against the static valve disc, and the other end is provided with a spring limiter. The valve disc mechanism can reciprocate under the action of the drilling fluid and the return spring, thereby generating a periodic impact load.

[0010] In one embodiment, the pressure transmission mechanism also includes a voltage divider, the inner end of the punch is adapted to be connected to the voltage divider, and the end extends to the outer side of the lower end surface of the built-in drill bit part. The voltage divider is configured to distribute the impact load and drilling pressure generated by the impactor, and transmit them to each of the impact teeth through the corresponding punch.

[0011] In one embodiment, the voltage divider is constructed in a cylindrical shape, and a hemispherical groove for adapting and connecting with the lower end surface of the impact rod is provided in the middle of the upper end of the voltage divider, and a plurality of circumferentially uniformly distributed straight grooves are provided on the outer wall surface of the voltage divider, and the straight grooves extend axially, and an arc-shaped groove for adapting and connecting with the upper end of the punch is provided on the lower end surface of the voltage divider.

[0012] In one embodiment, a cylindrical connecting portion is provided at the first end of the punch, and the connecting portion is used for adapting and connecting with the hemispherical groove. A mounting hole extending axially inward is provided at the second end of the punch, and the impact tooth is installed in the mounting hole.

[0013] In one embodiment, a cylindrical hole extending axially inward is provided in the bottom center area of ​​the drill bit body, and an inner rock-breaking tooth is provided at the bottom of the cylindrical hole. The inner rock-breaking tooth can split and crush the core rock formed in the cylindrical hole.

[0014] In one embodiment, a plurality of circumferentially distributed first blades are provided on the end face of the convex outer ring, the first blades are provided with a plurality of first cutting teeth, and a plurality of circumferentially distributed second blades are provided on the end face of the drill body, the second blades are provided with a plurality of second cutting teeth.

[0015] In one embodiment, the height difference between the middle end face of the drill body and the convex outer ring end face is greater than 20 mm.

[0016] In one embodiment, a joint for connecting other drilling tools is fixed on the upper end surface of the housing.

[0017] Compared with the prior art, the advantages of this application are:

[0018] When the impact shear composite drill bit for hard formations according to the present invention contacts the bottom of the well and starts drilling, the convex outer ring of the drill bit body first contacts the bottom of the well and cuts out a groove, thereby significantly improving the penetration capacity and rock breaking efficiency of the convex outer ring in the hard formation. After the outer ring formation at the bottom of the well is broken, the bottom of the well rock inside forms a core column, which greatly reduces the confining pressure strength of the formation. The impact teeth and the second cutting teeth on the bottom surface of the drill bit body can produce tensile splitting damage to the core column, thereby greatly improving the rock breaking efficiency. At the same time, after the bottom of the well is shaped, the internal core column can play a good straightening role, thereby effectively suppressing the lateral vibration of the impact shear composite drill bit, which is very beneficial to enhance its stability, thereby protecting the impact shear composite drill bit and extending its service life. The impact load generated by the impact device acts concentratedly on the impact teeth. The impact load of a single impact tooth is large, which is beneficial to the generation, convergence and penetration of microcracks, further improving the rock breaking efficiency. In addition, the impact shear composite drill bit requires less rock-breaking drilling pressure and torque, and can produce tensile splitting damage to the rock, thereby reducing the demand for rock-breaking energy, which is very beneficial to speeding up hard formations and at the same time alleviates the stick-slip motion of the drill bit. The core of the impact shear composite drill bit is configured as a micro-core structure, and by providing internal rock-breaking teeth, the internal rock-breaking teeth can produce tensile damage to the core rock to crush small rock blocks, greatly improving the rock-breaking efficiency of the core of the impact shear composite drill bit and significantly improving the mechanical drilling speed of the impact shear composite drill bit. The impact shear composite drill bit combines multiple rock-breaking mechanisms such as impact and shearing, greatly improving the mechanical drilling speed, effectively extending the service life, and expanding the scope of use of hard formation speed-up, which is very beneficial to improving rock-breaking efficiency and enhancing stability performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described below with reference to the accompanying drawings.

[0020] Figure 1 The structure of an impact shearing composite drill bit for hard formations according to the present invention is shown.

[0021] Figure 2 It is a schematic diagram of rock breaking at the bottom of a well by using an impact shear composite drill bit to break rock.

[0022] Figure 3 and Figure 4 The structure of the voltage divider in the impact device is shown.

[0023] Figure 5 The structure of the punch in the impact device is shown.

[0024] Figure 6 The installation structure of the punch in the drill body is schematically shown.

[0025] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0026] The present invention will be described below with reference to the accompanying drawings.

[0027] In the present application, it should be noted that the end of the impact shear composite drill bit for hard formations lowered into the wellbore away from the wellhead is defined as the lower end or similar terms, and the end close to the wellhead is defined as the upper end or similar terms.

[0028] Figure 1 The structure of the impact shearing composite drill bit 100 for hard formations according to the present invention is shown. Figure 1 As shown, the impact shearing composite drill bit 100 includes a drill bit body 10 and an impact device 30 arranged at the upper end of the drill bit body 10. The impact device 30 assists the drill bit body 10 in cutting and crushing the bottom hole rock. According to the present invention, a convex outer ring 12 extending axially outward is provided on the lower end face of the drill bit body 10. The convex outer ring 12 is annular. A plurality of first blades (not shown) uniformly or non-uniformly distributed in the circumferential direction are provided on the end face of the convex outer ring 12, and the first blades are extended radially. The number of the first blades is 4 to 9. A plurality of first cutting teeth are provided on the first blade, and the plurality of first cutting teeth are arranged in rows along the first blade, preferably 1-3 rows. The diameter of the first cutting tooth is set to 8 to 19 mm. The plurality of first cutting teeth may include at least one non-planar cutting tooth, for example, a non-planar cutting tooth such as a conical tooth or an axe-shaped tooth may be used. This is beneficial to enhancing the impact resistance of the first cutting tooth, enhancing the hydraulic cooling effect and avoiding thermal wear, thereby effectively enhancing the rock breaking effect, improving the rock breaking efficiency and extending the service life of the first cutting tooth.

[0029] In this embodiment, first chip removal grooves are formed between the first blades adjacent to each other in the circumferential direction, and first water holes (not shown) are respectively arranged in the first chip removal grooves. During operation, the first water holes can optimize the hydraulic performance of the drill bit, so that the first cutting teeth can be cleaned and cooled in time, effectively preventing the first cutting teeth from being wrapped by cuttings, which is very beneficial to improving the mechanical drilling speed of the drill bit body 10 and extending the life of the impact shear composite drill bit 100.

[0030] In one embodiment, a cylindrical hole (not shown) extending axially inward may be provided at the bottom core of the drill bit body 10 to form a micro-core structure. An inner rock-breaking tooth (not shown) is provided at the bottom of the cylindrical hole. The inner rock-breaking teeth may be, for example, non-planar cutting teeth such as conical teeth and axe-shaped teeth. The diameter of the cylindrical hole is 15 to 25 mm, and the axial extension length is less than 30 mm. During operation, the rock-breaking efficiency of the core of a conventional drill bit is extremely low, resulting in the formation of micro-core rock in the core rock. The inner rock-breaking teeth can split and crush the micro-core rock at the bottom of the well to form rock cuttings, and the formed rock cuttings are discharged from the drill bit chip groove. The inner rock-breaking teeth can significantly improve the rock-breaking efficiency of the core of the drill bit, and further improve the rock-breaking efficiency of the impact shear composite drill bit 100.

[0031] According to the present invention, a plurality of second blades (not shown) distributed in the circumferential direction are provided on the lower end surface of the drill bit body 10, and the second blades are extended radially. The number of second blades is 2 to 5. A plurality of second cutting teeth are provided on the second blade wing 21, and the plurality of second cutting teeth are arranged in a row along the second blade. The diameter of the second cutting teeth is set to 8 to 16 mm. At least one of the second cutting teeth is a non-planar cutting tooth, for example, a non-planar cutting tooth such as a conical tooth or an axe-shaped tooth can be used. This is conducive to enhancing the impact resistance of the second cutting teeth, enhancing the hydraulic cooling effect and avoiding thermal wear, thereby effectively enhancing the rock breaking effect, improving the rock breaking efficiency, and extending the service life of the second cutting teeth.

[0032] Similarly, a second chip removal groove is formed between the circumferentially adjacent second blades, and a second water hole (not shown) is respectively arranged in the second chip removal groove. During operation, the second water hole can optimize the hydraulic performance of the drill bit, so that the second cutting teeth can be cleaned and cooled in time, effectively preventing the rock chips from wrapping around the second cutting teeth, which is very beneficial to improving the mechanical drilling speed of the drill bit body 10 and extending the life of the impact shear composite drill bit 100.

[0033] According to the present invention, the outer diameter of the drill body 10 is set to be no less than 215.9 mm. The ratio of the outer diameter of the middle bottom surface of the drill body 10 with the second blade to the outer diameter of the convex outer ring 12 is set to be in the range of 0.3 to 0.6.

[0034] According to the present invention, the height difference between the middle end face of the drill body 10 provided with the second blade and the end face of the convex outer ring 12 is greater than 20 mm. That is, the middle end face of the drill body 10 is axially recessed at least 20 mm relative to the end face of the convex outer ring 12 of the drill body 10. Figure 2 The following is a schematic diagram of the bottom hole rock breaking by the impact shear composite drill bit. Figure 2 As shown, during the rock breaking operation, the convex outer ring 12 of the drill bit body 10 cuts an annular groove at the bottom of the well, so that the bottom well rock inside the convex outer ring 12 is formed into a core column with a dome-shaped top, and the second cutting teeth on the middle end face of the drill bit body 10 cause pre-crushing and tensile splitting damage to the core column, thereby performing rock breaking construction.

[0035] According to the present invention, the impact device 30 is configured to generate periodic axial impact loads, thereby causing tensile splitting damage to the bottom rock of the well to perform rock breaking operations. Figure 1As shown, the impact device 30 is arranged at the upper end of the drill bit body 10, and the impact device includes a cylindrical shell 31, a driving mechanism 40 arranged in the shell 31 from top to bottom, an impactor 50 for generating an impact load, and a pressure transmission mechanism 60 arranged in the drill bit body 10. The pressure transmission mechanism 60 includes at least one punch 62 that penetrates the drill bit body 10, and an impact tooth 70 is provided at the end of the punch 62. The pressure transmission mechanism 60 is used to distribute the impact load generated by the impactor 50 and transmit it to each impact tooth 70 accordingly. The number of impact teeth 70 can be set to 1 to 3 according to the formation conditions, wherein the harder the formation, the fewer the number of impact teeth 70.

[0036] According to the present invention, the impactor 50 includes an impact rod 51, a Figure 1 The valve disc mechanism (the upper end in the middle) and the driving mechanism 40 are at the upper end of the valve disc mechanism. The valve disc mechanism includes a static valve disc 52 and a dynamic valve disc 53. The static valve disc 52 is fixedly connected to the upper end of the impact rod 51, and the upper end surface of the static valve disc 52 contacts the lower end surface of the dynamic valve disc 53, and the dynamic valve disc 53 can rotate relative to the static valve disc 52. The driving mechanism 40 includes a guide wheel 41 and an impeller 42 rotatably connected to the guide wheel 42. The guide wheel 41 is fixedly connected to the inner surface of the housing 31 so that the guide wheel 41 does not rotate. The upper end of the impeller 42 is rotatably connected to the guide wheel 41 through a bearing, and the lower end of the impeller 42 is fixedly connected to the upper end surface of the dynamic valve disc 53. Under the action of the guide wheel 41, the drilling fluid is diverted to the impeller 42, and drives the impeller 42 to rotate to generate rotational power, thereby driving the dynamic valve disc 53 to rotate.

[0037] According to the present invention, a first eccentric flow channel (not shown) and a second eccentric flow channel (not shown) are respectively provided on the static valve disc 52 and the dynamic valve disc 53. As the dynamic valve disc 53 rotates, the flow area of ​​the valve disc mechanism changes periodically. The inner diameter and eccentric size of the first eccentric flow channel and the second eccentric flow channel are set according to actual calculations, and the first eccentric flow channel and the second eccentric flow channel form an eccentric relationship. The static valve disc 52 is fixedly connected to the impact rod 51 and does not rotate, and the dynamic valve disc 53 can rotate under the action of the driving mechanism 53. Therefore, as the dynamic valve disc 53 rotates, the flow area of ​​the valve disc mechanism changes periodically, thereby causing the pressure on the upper end surface of the dynamic valve disc 53 to change continuously. The pressure acts on the upper end surface of the dynamic valve disc 53 to form a periodically changing liquid column pressure. Thus, the valve disc mechanism can generate periodic impact loads, which are then transmitted downward to the pressure transmission mechanism 60 through the impact rod 51, and finally transmitted to each impact tooth 40, so that the impact tooth 40 can pre-crush and tensile splitting damage the bottom hole rock, greatly improving the rock breaking efficiency of the impact shear composite drill bit 100. In addition, the impact load is a high-frequency change, and its frequency depends on the frequency of rotation of the driving mechanism 53, and its change amplitude depends on the amplitude of the change of the flow area between the moving valve disc 53 and the static valve disc 52.

[0038] In this embodiment, the impactor 50 further includes a return spring 54 sleeved on the outer periphery of the impact rod 51. One end of the return spring 54 ( Figure 1 The upper end of the valve body 50 abuts against the lower end surface of the static valve disc 52, and the other end ( Figure 1 A spring stopper 55 is provided at the lower end of the movable valve disc 53. The spring stopper 55 can axially limit the reset spring 54 and can straighten the impact rod 51 to ensure that the impact rod 51 transmits the axial drilling pressure and impact load downward. As a result, the valve disc mechanism can reciprocate under the action of the drilling fluid and the reset spring 54, thereby generating a periodic impact load. The specific process is as follows: when the movable valve disc 53 rotates until the flow area of ​​the valve disc mechanism reaches a minimum, the pressure generated by the valve disc mechanism is the maximum, so that the valve disc mechanism pushes the impact rod 51 to move downward to generate an impact load. At this time, the valve disc mechanism compresses the reset spring 54, and the reset spring 54 stores energy. When the movable valve disc 53 continues to rotate and the flow area of ​​the valve disc mechanism gradually increases, until it reaches a maximum, the pressure generated by the valve disc mechanism is the minimum. At this time, the reset spring 54 stretches and pushes the valve disc mechanism to move upward, thereby resetting the valve disc mechanism. As the movable valve disc 53 rotates continuously, the valve disc mechanism continues to reciprocate, thereby generating an impact load periodically.

[0039] Figure 3 and Figure 4 61 shows the structure of the voltage divider. In one embodiment, Figure 3 and Figure 4 As shown, the voltage divider 61 is constructed in a cylindrical shape. A hemispherical groove 611 is provided inside the upper end of the voltage divider 61, and the hemispherical groove 611 is used to adapt and connect with the lower end surface of the impact rod 51. A plurality of circumferentially distributed straight grooves 612 are provided on the outer wall surface of the voltage divider 61, and the straight grooves 622 are provided to extend in the axial direction, and the straight grooves 622 are used to allow the drilling fluid to flow. A plurality of arc-shaped grooves 613 are provided on the lower end surface of the voltage divider 61, and the arc-shaped grooves 613 are provided to extend in the radial direction and are distributed at intervals in the circumferential direction. Figure 5As shown, the punch 62 is configured as a long rod-shaped structure. At the same time, a cylindrical connecting portion 621 is provided at the upper end of the punch 62, and the cylindrical connecting portion 621 is vertically arranged with the main body of the punch 62. The punch 62 is adapted to be connected with the hemispherical groove 613 of the voltage divider 61 through the connecting portion 621. The drill body 10 is provided with a through hole for the punch 62 to pass through. The central axis of the through hole is arranged at a certain angle to the central axis of the voltage divider 61. Two upper and lower limiting rings 63 (not shown) are provided in the through hole to form a shoulder structure, and the limiting ring 63 is connected to the through hole by a thread. The outer peripheral surface of the punch 62 is provided with a protrusion 622 to form a stroke limiting step, and the protrusion 622 forms a limit on the stroke of the punch 62 through two limiting rings 63. An energy storage spring (not shown) is installed between the front end surface of the punch protrusion 622 and the limiting ring 63 to realize impact energy storage to ensure that the punch 62 can reciprocate. Figure 6 The mounting structure of the punch 62 is shown.

[0040] A mounting hole extending axially inward is provided at the end of the punch 62, and the impact tooth 70 is installed in the mounting hole. The impact tooth 70 performs rock breaking operation under the action of impact load.

[0041] According to the present invention, a joint 32 for connecting other drilling tools is provided on the upper end surface of the housing 31 .

[0042] The following is a brief description of the working process of the impact shear composite drill bit 100 for hard formations according to the present invention. When the impact shear composite drill bit 100 contacts the bottom of the well and starts drilling, first, the convex outer ring 12 of the drill bit body 10 contacts the bottom of the well, and then cuts out an annular groove at the bottom of the well, so that the bottom of the well rock inside the convex outer ring 12 is formed into a core column with a dome-shaped top. After the outer ring formation of the bottom of the well is broken, the formation confining pressure strength is greatly reduced, and the impact teeth 70 and the second cutting teeth can produce pre-crushing and tensile splitting damage to the core column. The impact teeth 70 generate periodic impact loads under the action of the impactor 50 to perform pulsed rock breaking construction on the core column. The crown shape of the impact shear composite drill bit 100 can form a three-step bottom of the well, which is very beneficial to enhance the stability of the impact shear composite drill bit 100 and improve its mechanical drilling speed, thereby improving rock breaking efficiency.

[0043] When the impact shear composite drill bit 100 for hard formations according to the present invention contacts the bottom of the well and starts drilling, the convex outer ring 12 of the drill bit body 10 first contacts the bottom of the well and cuts out a groove, thereby significantly improving the penetration capacity and rock breaking efficiency of the impact shear composite drill bit 100 in the hard formation. After the outer ring formation of the bottom of the well is broken, a core column is formed inside, which greatly reduces the confining pressure strength of the formation. The impact teeth 70 and the second cutting teeth can produce tensile splitting damage to the core column, thereby greatly improving the rock breaking efficiency. At the same time, after the bottom of the well is formed, the internal core column can play a good straightening role, thereby effectively suppressing the lateral vibration of the impact shear composite drill bit 100, which is very beneficial to enhancing its stability, thereby protecting the impact shear composite drill bit 100 and extending its service life. The impact load generated by the impact device 30 acts on the impact teeth 70, and the impact load of a single impact tooth 70 is large, which is beneficial to the generation, convergence and penetration of microcracks, and further improves the rock breaking efficiency. In addition, the impact shear composite drill bit 100 requires less rock-breaking drilling pressure and torque, which is very beneficial to speeding up hard formations, effectively reducing rock-breaking energy consumption, and alleviating the stick-slip motion of the drill bit. The core of the impact shear composite drill bit 100 is set as a micro-core structure, and by setting internal rock-breaking teeth, the internal rock-breaking teeth can crush the bottom hole rock corresponding to the core of the drill bit, greatly improving the rock-breaking efficiency of the core of the impact shear composite drill bit 100, and significantly improving the mechanical drilling speed of the impact shear composite drill bit 100. The impact shear composite drill bit 100 combines multiple rock-breaking mechanisms such as impact and shearing, greatly improving the mechanical drilling speed, which is very beneficial to improving rock-breaking efficiency and enhancing stability performance, effectively extending the service life, and expanding the scope of use of PDC drill bits in the field of speeding up hard formations.

[0044] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An impact shearing composite drill bit for hard formations, comprising: A drill body (10), wherein a convex outer ring (12) extending axially outward is provided on the lower end surface of the drill body; An impact device (30) is arranged at the upper end of the drill body, the impact device comprising a housing (31), a driving mechanism (40) arranged in the housing from top to bottom, an impactor (50) and a pressure transmission mechanism (60) arranged in the drill body, The pressure transmission mechanism comprises at least one punch (62) penetrating the drill body, an impact tooth (70) is provided at the end of the punch, and a plurality of second blades distributed in the circumferential direction are provided on the lower end surface of the drill body; wherein the impact device is configured to generate a periodic impact load under the action of the driving mechanism and the impactor, and transmit the periodic impact load to the impact tooth through the punch, so that the impact tooth generates a periodic impact load; The impactor comprises an impact rod (51), a valve disc mechanism arranged at one end of the impact rod, the valve disc mechanism comprises a static valve disc (52) and a dynamic valve disc (53), the static valve disc is fixedly connected to the upper end of the impact rod, the dynamic valve disc is arranged to be driven to rotate by the driving mechanism under the action of drilling fluid, so that the flow area of ​​the valve disc mechanism changes periodically, so that the valve disc mechanism forms a periodically changing pressure and transmits it downward to the impact tooth through the impact rod, when the dynamic valve disc rotates until the flow area of ​​the valve disc mechanism reaches a minimum, the pressure generated by the valve disc mechanism is maximum, so that the valve disc mechanism pushes the impact rod to move downward to generate an impact load, and when the dynamic valve disc rotates until the flow area of ​​the valve disc mechanism increases, the pressure generated by the valve disc mechanism decreases, so that the valve disc mechanism and the impact rod are reset; The pressure transmission mechanism also includes a voltage divider (61), the inner end of the punch is adapted to be connected with the voltage divider, and the end extends to the outer side of the lower end surface of the drill body, the voltage divider is constructed in a cylindrical shape, a hemispherical groove (611) for adapting and connecting with the lower end surface of the impact rod is provided in the middle of the upper end of the voltage divider, a plurality of circumferentially uniformly distributed straight grooves (612) are provided on the outer wall surface of the voltage divider, the straight grooves are extended in the axial direction, a circular arc groove (613) for adapting and connecting with the upper end of the punch is provided on the lower end surface of the voltage divider, a cylindrical connecting portion (621) is provided at the first end of the punch, the connecting portion is adapted to be connected with the circular arc groove, a mounting hole extending axially inward is provided at the second end of the punch, and the impact tooth is mounted in the mounting hole; The convex outer ring cuts an annular groove at the bottom of the well, and forms the bottom well rock inside the convex outer ring into a core column with a dome-shaped top. The impact teeth can cause pre-crushing and tensile splitting damage to the core column, thereby performing rock breaking construction.

2. The impact shearing composite drill bit according to claim 1, characterized in that: The driving mechanism comprises a guide wheel (41) and an impeller (42) rotatably connected to the guide wheel, the impeller is fixedly connected to the movable valve disc, and the drilling fluid is guided to the impeller under the action of the guide wheel and pushes the impeller to drive the movable valve disc to rotate.

3. The impact shearing composite drill bit according to claim 2, characterized in that: A first eccentric flow channel and a second eccentric flow channel are respectively provided on the movable valve disc and the stationary valve disc. As the movable valve disc rotates, the flow area of ​​the valve disc mechanism changes periodically.

4. The impact shearing composite drill bit according to any one of claims 1 to 3, characterized in that: The impactor further comprises a return spring (54) sleeved on the outer periphery of the impact rod, one end of the return spring abuts against the static valve disc, and the other end is provided with a spring limiter (55). The valve disc mechanism can reciprocate under the action of the drilling fluid and the return spring, thereby generating a periodic impact load.

5. The impact shearing composite drill bit according to claim 1, characterized in that: A cylindrical hole extending axially inward is provided in the bottom center area of ​​the drill bit body, and an inner rock-breaking tooth is provided at the bottom of the cylindrical hole. The inner rock-breaking tooth can split and crush the core rock formed in the cylindrical hole.

6. The impact shearing composite drill bit according to claim 1, characterized in that: A plurality of circumferentially distributed first blades are provided on the end surface of the convex outer ring, and the first blades are provided with a plurality of first cutting teeth. A plurality of circumferentially distributed second blades are provided on the end surface of the drill body, and the second blades are provided with a plurality of second cutting teeth.

7. The impact shearing composite drill bit according to claim 1, characterized in that: The height difference between the middle end face of the drill body and the convex outer ring end face is greater than 20 mm.

8. The impact shearing composite drill bit according to claim 1, characterized in that: A joint (32) for connecting other drilling tools is fixed on the upper end surface of the shell.

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