A drill bit with self-adaptive adsorption and real-time breaking function and a drilling method thereof

Abstract

This invention discloses a rock cuttings-assisted jet drill bit with adaptive adsorption and real-time crushing functions, and its drilling method. The drill bit body includes a main through-flow channel and several secondary flow channels. The main through-flow channel contains a confluence chamber, into which the secondary flow channels converge. Several chip guide holes are formed on the drill bit body and connected to the secondary flow channels. When the jet passes through the secondary flow channels, a negative pressure is generated in the chip guide holes to draw in rock cuttings. A rotary cutting device and a filter screen are provided in the secondary flow channels. Before the rock cuttings flow into the confluence chamber, they are sequentially crushed by the rotary cutting device and filtered by the filter screen. This invention integrates active rock cuttings collection, real-time crushing, and filtration functions, enabling efficient self-circulation of the abrasive and improving rock breaking efficiency using composite jet coupling technology.

Description

Technical Field

[0001] This invention relates to the field of geological drilling and well drilling technology, and in particular to a cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions and its drilling method. Background Technology

[0002] Regarding the abrasive issue, existing technologies mostly employ external circulation systems to replenish the abrasive. However, in ultra-short radius wellbores with limited space, additional abrasive injection not only increases equipment complexity but also exacerbates drill string wear. Although some solutions attempt to utilize rock cuttings as natural abrasive, their recovery devices lack active crushing and grading functions. Rock cuttings that are too large or unevenly distributed can easily clog the flow channels, making it difficult to achieve a stable and efficient self-supply of abrasive. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a rock cuttings-assisted jet drill bit and its drilling method with adaptive adsorption and real-time crushing functions. It integrates active rock cuttings collection, real-time crushing and filtering functions, can realize efficient self-circulation of abrasive, and improves rock breaking efficiency by using composite jet coupling technology.

[0004] Technical Solution: To achieve the above objectives, the present invention provides a rock cuttings-assisted jet drill bit with adaptive adsorption and real-time crushing functions, comprising a drill bit body, a main through-flow channel and several secondary flow channels within the drill bit body, a confluence chamber within the main through-flow channel, and the secondary flow channels converging into the confluence chamber; several chip guide holes are formed on the drill bit body, and the chip guide holes are connected to the secondary flow channels; when the jet passes through the secondary flow channels, a negative pressure is generated in the chip guide holes to draw in rock cuttings; a rotary cutting device and a filter screen are provided in the secondary flow channels, and before the rock cuttings are drawn into the confluence chamber with the jet, they are sequentially crushed by the rotary cutting device and filtered by the filter screen.

[0005] Furthermore, the secondary flow channel includes a tapered flow channel, a cuttings collection flow channel, and a crushing abrasive distribution channel connected in sequence; the tapered flow channel gradually narrows along the jet direction, the inner port of the chip guide hole is located at the outlet of the tapered flow channel, and the rotary cutting device and the filter screen are correspondingly arranged at the inlet of the crushing abrasive distribution channel.

[0006] Furthermore, the drill bit body includes a front guide section and a rear guide section that are connected separately. The cuttings collection channel is cut at the boundary between the front guide section and the rear guide section. The cuttings collection channel is opened when the front guide section and the rear guide section are separated.

[0007] Furthermore, the front guide portion has a female thread end face connected to the drill string at one end away from the rear guide portion; the rear guide portion has a drill bit crown separately connected to one end away from the front guide portion.

[0008] Furthermore, the front guide portion has an external thread section at one end facing the rear guide portion, and the rear guide portion has an internal thread section at one end facing the front guide portion, with the external thread section and the internal thread section being threadedly connected.

[0009] Furthermore, the edge of the internal thread section is provided with a positioning groove. When the front guide part and the rear guide part are connected, the positioning groove is spliced ​​into the outer port of the chip guide hole, so that the chip guide hole is also cut at the boundary between the front guide part and the rear guide part.

[0010] Furthermore, the rotary cutting device includes a tool holder and a rotary cutter. The tool holder is detachably installed at the inlet of the crushing abrasive channel, and the rotary cutter is rotatably installed on the tool holder. When the jet passes through the rotary cutter, it drives the rotary cutter to rotate.

[0011] Furthermore, the filter screen is detachably installed at the inlet of the abrasive crushing channel.

[0012] Furthermore, the main through-flow channel extends along the axial direction of the drill bit body, and a plurality of the secondary flow channels are distributed circumferentially at equal angles around the main through-flow channel.

[0013] Furthermore, a drilling method for a rock cuttings-assisted jet drill bit with adaptive adsorption and real-time crushing functions involves delivering a high-pressure jet to the main through-flow channel and several secondary channels during drilling. The high-pressure jet in the main through-flow channel is delivered to the jet nozzle at the front end of the drill bit body to crush the rock strata and form rock cuttings. The rock cuttings are sucked into the secondary channels through the chip guide holes and then enter the rotary cutting device for real-time crushing with the jet. After being classified by a filter screen, the crushed rock cuttings enter the confluence chamber through the crushing abrasive distribution channel and mix with the central main jet before entering the main through-flow channel to form a rock cuttings-assisted jet.

[0014] Beneficial effects: The rock cuttings-assisted jet drill bit and drilling method of the present invention, which have adaptive adsorption and real-time breaking functions, have the following beneficial effects:

[0015] 1) A negative pressure suction channel is formed by the chip guide hole array outside the drill bit body to actively adsorb and recover the annular rock cuttings; the rotary cutting device and filter screen are used to crush and filter the sucked rock cuttings in real time, and generate rock cutting abrasive that meets the particle size requirements in real time; avoid the flow channel being blocked by rock cuttings due to excessive size or uneven distribution, so as to achieve stable and efficient abrasive self-supply and reduce dependence on external abrasive supply.

[0016] 2) The modular split structure design allows key components such as the drill bit crown and rotary cutting device to be replaced independently, avoiding partial damage that could lead to overall scrapping and thus reducing maintenance costs. By replacing the rotary cutting elements in the rear guide and the drill bit crown, the drill bit can quickly adapt to the hardness requirements of different rock formations, enhancing its adaptability to various working conditions.

[0017] 3) The front and rear guide parts of the drill bit body are connected by a threaded connection, and the boundary between the front and rear guide parts corresponds to the cutting guide hole; during the process of rock cuttings being sucked into the cutting guide hole, an impact force will be generated on the cutting guide hole, which will cause the front and rear guide parts to maintain an aligned state at the cutting guide hole, so as to avoid the front and rear guide parts from rotating, thereby maintaining the structural stability of the drill bit body. Attached Figure Description

[0018] Appendix Figure 1 This is a schematic diagram of the overall structure of the drill bit;

[0019] Appendix Figure 2 This is the left view of the drill bit;

[0020] Appendix Figure 3 for Figure 2 AA section view;

[0021] Appendix Figure 4 This is a front view of the rotary cutting device;

[0022] Appendix Figure 5 for Figure 4 BB cross-sectional view. Detailed Implementation

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] As attached Figures 1 to 5 The aforementioned cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions includes a drill bit body. The drill bit body contains a main through-flow channel 3 and several secondary flow channels 9. A confluence chamber 16 is located within the main through-flow channel 3, and the secondary flow channels 9 converge into the confluence chamber 16. When a high-pressure jet is delivered into the drill bit body, the high-pressure jet enters the main through-flow channel 3 and the several secondary flow channels 9. The main through-flow channel 3 extends axially along the drill bit body, and the several secondary flow channels 9 are distributed equidistantly around the main through-flow channel 3.

[0025] The drill bit body has several cuttings guide holes 10, the number of which matches the number of auxiliary flow channels 9. Each cuttings guide hole 10 is connected to a corresponding auxiliary flow channel 9. In one embodiment, six auxiliary flow channels 9 are provided, evenly distributed circumferentially inside the drill bit body. There are also six cuttings guide holes 10, located on the outer circumferential surface of the drill bit body, each connected to one of the six auxiliary flow channels 9. When the high-pressure jet passes through the auxiliary flow channels 9, a negative pressure is generated within the cuttings guide holes 10, capable of drawing in rock cuttings, thereby achieving active collection and guidance of annular rock cuttings.

[0026] A rotary cutting device 12 and a filter screen 15 are also installed in the secondary flow channel 9. Before the rock cuttings flow into the confluence chamber 16 with the jet, they are crushed by the rotary cutting device 12 and filtered by the filter screen 15. Thus, the collected rock cuttings are crushed in real time by the rotary cutting device 12, and the crushed rock cuttings are then filtered by the filter screen 15 to obtain a rock cutting abrasive flow that meets the particle size requirements. This avoids the rock cuttings from clogging the flow channel due to excessive size or uneven distribution, thereby achieving stable and efficient abrasive self-supply and reducing dependence on external abrasive supply.

[0027] The secondary flow channel 9 includes a tapered flow channel 7, an abrasive collection flow channel 11, and a crushing abrasive distribution channel 8 connected in sequence. The tapered flow channel 7 gradually narrows along the jet direction, and the inner port of the chip guide hole 10 is located at the outlet of the tapered flow channel 7. This structural design utilizes the Venturi effect to accelerate the high-pressure jet as it passes through the tapered flow channel 7, thereby enhancing the negative pressure generated within the chip guide hole 10 and increasing its adsorption capacity for annular rock cuttings. In practical applications, the contraction ratio of the tapered flow channel 7 is generally 1:1.5-1:2.5.

[0028] The cuttings collection channel 11 is a constant-width channel, with its inner diameter larger than the outlet inner diameter of the tapered channel 7. This allows the cuttings collection channel 11 to hold more cuttings, improving the stability of the cuttings supply. The inlet inner diameter of the abrasive splitter channel 8 is smaller than the inner diameter of the cuttings collection channel 11. When the jet enters the abrasive splitter channel 8 from the cuttings collection channel 11, the jet is accelerated. The rotary cutting device 12 and the filter screen 15 are correspondingly arranged at the inlet of the abrasive splitter channel 8. The rotary cutting device 12 includes a tool holder 17 and a rotating cutter 14. The tool holder 17 is detachably installed at the inlet of the abrasive splitter channel 8, and the rotating cutter 14 is rotatably installed on the tool holder 17. The axis of the rotating cutter 14 is aligned with the axis of the drill bit body. When the accelerated jet passes through the rotating cutter 14, it drives the rotating cutter 14 to rotate at high speed, thereby crushing the cuttings.

[0029] In one embodiment, the rotary cutting device 12 employs a deep groove ball bearing 19 and a double-end mechanical seal, with the bearing front cover 18 and bearing rear cover 20 made of silicon carbide. The rotary cutting tool 14 is a PDC composite tool with a cutting edge inclination angle of 10°-15°, a tool tip radius of 0.3-0.5mm, and a Vickers hardness of HV3500-HV4500.

[0030] In one embodiment, the filter screen 15 is detachably installed within the abrasive crushing channel 8 via a snap-fit ​​structure, allowing the filter screen 15 to be replaced. In practical applications, the mesh size of the filter screen 15 is 0.5-2mm.

[0031] While the one-piece structure of traditional drill bits improves initial strength, it sacrifices maintainability. The harsh downhole environment makes critical components such as the drill bit crown 4 and nozzles prone to failure. The one-piece design prevents quick replacement in case of partial damage, necessitating the scrapping of the entire drill bit and significantly increasing operating costs. Therefore, the drill bit in this invention adopts a split design. Specifically, the drill bit body includes a split-connected front guide section 1 and a rear guide section 2. The front guide section 1, at its end away from the rear guide section 2, has a female thread end face connected to the drill string. The rear guide section 2, at its end away from the front guide section 1, is separately connected to the drill bit crown 4. When the front guide section 1, rear guide section 2, or drill bit crown 4 is damaged, they can be replaced individually without rendering the entire drill bit unusable, thereby reducing costs.

[0032] In addition, the abrasive collection channel 11 is cut at the boundary between the front guide 1 and the rear guide 2. When the front guide 1 and the rear guide 2 are separated, the abrasive collection channel 11 is opened accordingly, which facilitates the maintenance or replacement of the rotary cutting device 12 and the filter screen 15.

[0033] The leading part 1 has an external threaded section 21 at one end facing the rear leading part 2, and the rear leading part 2 has an internal threaded section 22 at one end facing the leading part 2. The external threaded section 21 and the internal threaded section 22 are threadedly connected, allowing the rear leading part 2 to fit onto the leading part 1. During drill bit assembly, the leading part 1 and the rear leading part 2 are threaded together using the external threaded section 21 and the internal threaded section 22. The standard thread is API NC50 type, and a fluororubber sealing ring 5 is placed at the thread engagement point to ensure sealing, forming the drill bit body. The drill bit crown 4 is then connected to the rear leading part 2 using the same API standard thread and fluororubber sealing ring 5. After the leading part 1, the rear leading part 2, and the drill bit crown 4 are tightly connected, they together constitute the axial main through-flow channel 3.

[0034] The leading section 1, the rear leading section 2, and the drill bit crown 4 all adopt a modular design for easy independent replacement later. The leading section 1 and the rear leading section 2 are preferably made of high-strength tungsten-nickel alloy with a tensile strength ≥1200Mpa. The drill bit crown 4 is inlaid with a hard alloy wear-resistant layer with a thickness of 3-5mm.

[0035] After the high-pressure jet impacts the blades of the rotating cutter 14, it pushes the rotating cutter 14 to rotate around its axis. After the rotating cutter 14 rotates, it in turn generates a tangential thrust on the jet, causing the jet to rotate as it passes through the rotating cutter 14. Multiple auxiliary flow channels 9 are circumferentially distributed within the drill bit body. Because the amount of rock cuttings sucked into each auxiliary flow channel 9 is not uniform, the rotating jets generated by each auxiliary flow channel 9 are not uniform. The multiple rotating jets produce a complex and multifaceted combined effect. Since the leading section 1 and the rear leading section 2 are connected by a threaded structure, the combined effect of the multiple rotating jets may cause relative rotation between the leading section 1 and the rear leading section 2, affecting the structural stability of the drill bit body.

[0036] To solve the above problems, in this invention, the chip guide hole 10 is not separately provided on the front guide portion 1 or the rear guide portion 2, but is provided as shown in the attached figure. Figure 1 and 3 As shown, a positioning groove 13 is provided on the edge of the internal thread section 22 of the rear guide portion 2. The outline shape of the positioning groove 13 is completely consistent with the cross-sectional shape of the chip guide hole 10. When the front guide portion 1 is connected to the rear guide portion 2, the positioning groove 13 is correspondingly spliced ​​to form the outer port of the chip guide hole 10, so that the boundary between the front guide portion 1 and the rear guide portion 2 also correspondingly divides the chip guide hole 10. During the process of the chip guide hole 10 continuously sucking in rock cuttings, if there is a slight relative rotation between the front guide portion 1 and the rear guide portion 2, it will cause the positioning groove 13 to be misaligned to a certain extent at the outer port of the chip guide hole 10, thereby obstructing the interior of the chip guide hole 10. Due to the presence of negative pressure suction, the rock cuttings sucked into the cuttings guide hole 10 will exert an impact force on the misaligned positioning groove 13, thereby restoring the positioning groove 13 from a state of being misaligned with the cuttings guide hole 10 to a state of being aligned with the cuttings guide hole 10. This corrects the slight relative displacement between the front guide part 1 and the rear guide part 2, preventing the front guide part 1 and the rear guide part 2 from continuously accumulating slight relative displacement under the action of multiple rotating jets, thus maintaining the structural stability of the drill bit body.

[0037] Furthermore, during the splicing process of the front guide 1 and the rear guide 2 via a threaded structure, the positioning groove 13 can be used as a positioning mark to control the tightness of the connection between the front guide 1 and the rear guide 2.

[0038] This invention also provides a drilling method for a rock cuttings-assisted jet drill bit with adaptive adsorption and real-time crushing functions. During drilling, a high-pressure jet is delivered to the main through-flow channel 3 and several secondary through-flow channels 9. The high-pressure jet in the main through-flow channel 3 is delivered to the jet nozzle 6 at the front end of the drill bit body, crushing the rock strata and forming rock cuttings. The rock cuttings are sucked into the secondary through-flow channels 9 through the chip guide holes 10, and then enter the rotary cutting device 12 for real-time crushing. After being classified by a filter screen 15, the crushed rock cuttings enter the confluence chamber 16 through the abrasive distribution channel 8 and mix with the central main jet, then enter the main through-flow channel 3 to form a rock cuttings-assisted jet. When the rock strata hardness changes, the jet velocity in the tapered channel 7 can be increased, and the rotational speed of the rotating cutter 14 in the rotary cutting device 12 can be increased, adaptively improving the crushing capacity.

[0039] The working principle of this invention is as follows: High-pressure drilling fluid of 80-120 MPa is delivered to the drill bit tip through the axial main through-flow channel 3. A portion of the fluid passes through the central jet nozzle 6 to form a high-speed central jet, directly impacting the rock formation at the bottom of the well for initial fracturing; the other portion of the fluid enters the secondary flow channel 9. During drilling, rock cuttings generated in the annulus are actively recovered. This function is achieved through an array of radially uniformly distributed cuttings guide holes 10 located on the drill bit body wall. The cuttings guide holes 10 are directly opposite the outlet of the tapered flow channel 7. When the fluid flows through the tapered flow channel 7, a negative pressure suction channel is formed at the inlet of the cuttings guide holes 10 using the Venturi effect, efficiently drawing annular rock cuttings into the flow channel system. The sucked-in rock cuttings enter the drill bit body along with the fluid. The cuttings and fluid are then guided to the rotary cutting device 12 integrated within the rear guide section 2. The rotating cutter 14 crushes the sucked-in rock cuttings to a particle size of 0.5-2 mm in real time, and then filters out the rock cuttings that meet the particle size requirements through the filter screen 15. The rock cuttings that meet the particle size requirements are accelerated to 150-200 m / s within the flow channel and then ejected through the crushing abrasive distribution channel 8. The accelerated rock cuttings-containing abrasive jet enters the confluence chamber 16. Within the confluence chamber 16, this abrasive jet couples with the central jet from the main through-flow channel 3, forming a more concentrated and powerful composite impact jet that works together against the rock formation at the bottom of the well, achieving efficient rock breaking.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions, characterized in that: The drill bit body includes a main through-flow channel (3) and several secondary through-flow channels (9). The main through-flow channel (3) has a confluence chamber (16), and the several secondary through-flow channels (9) converge into the confluence chamber (16). The drill bit body has several chip guide holes (10), which are connected to the secondary through-flow channels (9). When the jet passes through the secondary through-flow channels (9), a negative pressure is generated in the chip guide holes (10) to draw in rock cuttings. The secondary through-flow channels (9) are equipped with a rotary cutting device (12) and a filter screen (15). Before the rock cuttings flow into the confluence chamber (16) with the jet, they are successively crushed by the rotary cutting device (12) and filtered by the filter screen (15).

2. The rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 1, characterized in that: The secondary flow channel (9) includes a tapered flow channel (7), a rock cuttings collection flow channel (11), and a crushing abrasive distribution channel (8) connected in sequence; the tapered flow channel (7) gradually narrows along the jet direction, the inner port of the chip guide hole (10) is located at the outlet of the tapered flow channel (7), and the rotary cutting device (12) and the filter screen (15) are respectively arranged at the inlet of the crushing abrasive distribution channel (8).

3. A rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 2, characterized in that: The drill bit body includes a front guide (1) and a rear guide (2) that are connected separately. The cuttings collection channel (11) is cut at the boundary between the front guide (1) and the rear guide (2). The cuttings collection channel (11) is opened when the front guide (1) and the rear guide (2) are separated.

4. A rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 3, characterized in that: The front guide (1) is provided with a female thread end face connected to the drill string at one end away from the rear guide (2); the rear guide (2) is separately connected to the drill bit crown (4) at one end away from the front guide (1).

5. A rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 3, characterized in that: The front guide (1) is provided with an external thread section (21) at one end facing the rear guide (2), and the rear guide (2) is provided with an internal thread section (22) at one end facing the front guide (2). The external thread section (21) and the internal thread section (22) are threadedly connected.

6. A rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 5, characterized in that: The edge of the internal thread section (22) is provided with a positioning groove (13). When the front guide part (1) is connected to the rear guide part (2), the positioning groove (13) is spliced ​​into the outer port of the chip guide hole (10), so that the chip guide hole (10) is also cut at the boundary between the front guide part (1) and the rear guide part (2).

7. A rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 2, characterized in that: The rotary cutting device (12) includes a tool holder (17) and a rotary cutter (14). The tool holder (17) is detachably installed at the inlet of the crushing abrasive channel (8). The rotary cutter (14) is rotatably installed on the tool holder (17). When the jet passes through the rotary cutter (14), it drives the rotary cutter (14) to rotate.

8. A rock cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 2, characterized in that: The filter screen (15) is detachably installed at the inlet of the abrasive crushing channel (8).

9. A cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 1, characterized in that: The main through-flow channel (3) extends along the axial direction of the drill bit body, and a number of the secondary flow channels (9) are distributed circumferentially at equal angles around the main through-flow channel (3).

10. The drilling method of a cuttings-assisted jet drill bit with adaptive adsorption and real-time breaking functions according to claim 1, characterized in that: When the drill bit body is drilling, the high-pressure jet is delivered to the main through channel (3) and several auxiliary channels (9); the high-pressure jet in the main through channel (3) is delivered to the jet nozzle (6) at the front end of the drill bit body to break the rock layer and form rock cuttings. The rock cuttings are sucked into the auxiliary channels (9) through the chip guide hole (10) and then enter the rotary cutting device (12) for real-time breaking with the jet. After the rock cuttings are classified by the filter screen (15), they enter the confluence chamber (16) through the crushing abrasive distribution channel (8) and mix with the central main jet, and enter the main through channel (3) to form the rock cutting auxiliary jet.

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