A low-pressure, high-efficiency rock breaking method and drill bit

Abstract

This application provides a low-pressure-to-drill-force (LPD) high-efficiency rock-breaking method and drill bit, belonging to the field of drill bit technology. The low-pressure-to-drill-force high-efficiency rock-breaking drill bit includes a main body, a drilling section, and a reaming section. The drilling section is located at the end of the main body, and its outer circumferential surface has multiple cutting wings, each evenly distributed radially. The cutting wings are arc-shaped, and multiple cutting teeth are evenly fixed along the arc direction on each cutting wing. The reaming section is located on the outer circumferential surface of the main body, and has a conical helical structure. The small-diameter end of the reaming section abuts against the drilling section, and multiple reaming teeth are evenly fixed along the helical direction on the reaming section. Thus, the drilling section, through stable contact with the formation via the arc-shaped cutting wings, can suppress drill bit vibration and deflection, enhancing drilling stability. Simultaneously, the arrangement of the cutting teeth in the conical helical structure converts rotational kinetic energy into axial propulsion force, enhancing the drill bit's self-propelled capability, reducing dependence on external drilling pressure, and achieving low-pressure-to-drilling.

Description

Technical Field

[0001] This application relates to the field of drill bit technology, and in particular to a low-pressure, high-efficiency rock-breaking method and drill bit. Background Technology

[0002] In the exploration and development of energy resources such as oil, natural gas, and geothermal energy, the drill bit is the core tool for drilling operations, and its performance directly affects drilling efficiency, cost, and safety.

[0003] During the process of breaking rocks at the bottom of a well, the drill bit must overcome the compressive and shear strength of the formation. Traditional drill bits rely on axial drilling pressure and rotational torque provided by external equipment as the energy source for rock breaking. However, with the increase in drilling depth and formation complexity (such as hard rock formations, high-stress layers, or salt gypsum layers), the demand for drilling pressure and torque of conventional drill bits increases significantly, leading to increased load on external equipment and higher drilling costs. In addition, in directional drilling or horizontal well operations, the stability of the drill bit is crucial for wellbore trajectory control. If the drill bit structure design is unreasonable, vibration, deviation, or even stuck pipe accidents can easily occur.

[0004] Therefore, in order to meet the needs of efficient and safe drilling under complex geological conditions, there is an urgent need to provide a drill bit structure that can reduce the dependence on drilling pressure, improve rock breaking efficiency, and ensure stability during the drilling process. Summary of the Invention

[0005] This application provides a low-pressure, high-efficiency rock-breaking method and drill bit to address the shortcomings of related technologies.

[0006] On one hand, this application provides a low-pressure, high-efficiency rock-breaking drill bit, including a main body, a drilling section, and a reaming section. The drilling section is located at the end of the main body, and has multiple cutting wings on its outer peripheral surface. Each cutting wing is radially distributed evenly, and the cutting wings are arc-shaped. Multiple cutting teeth are uniformly fixed on the cutting wings along the arc direction. The reaming section is located on the outer peripheral surface of the main body, and has a conical spiral structure. The small-diameter end of the reaming section abuts against the drilling section. Multiple reaming teeth are uniformly fixed on the reaming section along the spiral direction. The reaming teeth are configured to contact the formation during the drilling process of the main body to convert rotational kinetic energy into axial thrust.

[0007] In one possible implementation, the low-drilling-pressure, high-efficiency rock-breaking drill bit provided in this application includes a reaming section comprising a reaming wing. The reaming wing is disposed on the outer peripheral surface of the main body and extends spirally along the axial direction of the main body. The thickness of the reaming wing decreases sequentially in the direction toward the drilling section to form a conical spiral structure. Multiple reaming teeth are uniformly arranged along the spiral extension path of the reaming wing.

[0008] In one possible implementation, the low-drilling-pressure, high-efficiency rock-breaking drill bit provided in this application includes a reaming section comprising at least two reaming wings. Each reaming wing is evenly distributed on the outer peripheral surface of the main body. The reaming wings are arc-shaped, and the thickness of the reaming wings decreases sequentially along the direction toward the drilling section. Furthermore, each reaming wing is oriented in the same direction to form a conical spiral structure. Multiple reaming teeth are evenly fixed on the reaming wings along the arc direction.

[0009] In one possible implementation, the low-drill-pressure, high-efficiency rock-breaking drill bit provided in this application has the height of each reaming tooth on the same reaming blade varying radially to form staged cutting; and / or, the reaming teeth are semi-cylindrical or horseshoe-shaped.

[0010] In one possible implementation, the low-drill-pressure, high-efficiency rock-breaking drill bit provided in this application has 4-9 reaming wings; and / or, the pitch between two adjacent reaming wings is 60-100 cm.

[0011] In one possible implementation, the low-drilling-pressure, high-efficiency rock-breaking drill bit provided in this application has multiple water holes on its main body; there are 2-4 water holes between two adjacent reaming wings.

[0012] In one possible implementation, the low-pressure, high-efficiency rock-breaking drill bit provided in this application has a reaming section length of 30-50 cm; and / or, the outer diameter of the drilled section accounts for 60%-80% of the diameter of the large-diameter end of the reaming section, and the difference between the outer diameter of the drilled section and the diameter of the small-diameter end of the reaming section is 0.2-0.4 mm.

[0013] In one possible implementation, the low-drilling-pressure, high-efficiency rock-breaking drill bit provided in this application includes a drilling section comprising a cone, a nose, a shoulder, and a gauge-keeping section arranged sequentially; the cone, nose, shoulder, and gauge-keeping section together form a cover cavity with an opening on one side, and the cover cavity matches the main body; part of the main body is located inside the cover cavity, and the cutting wings are simultaneously arranged on the cone, nose, shoulder, and gauge-keeping section.

[0014] On the other hand, this application provides a low-drill-pressure, high-efficiency rock-breaking method, which uses any of the low-drill-pressure, high-efficiency rock-breaking drill bits described above to drill a hole in the formation to be drilled. The method includes:

[0015] According to the first preset calculation formula, the first working load of all cutting teeth of the low drilling pressure high efficiency rock breaking drill bit on the formation to be drilled is determined, and according to the second preset calculation formula, the second working load of all reaming teeth of the low drilling pressure high efficiency rock breaking drill bit on the formation to be drilled is determined.

[0016] Under the action of external preset drilling pressure and external preset torque, the formation to be drilled is drilled to the first preset depth by a low-drill-pressure, high-efficiency rock-breaking drill bit.

[0017] Based on the first working load and the second working load, the external drilling pressure and the external torque are adjusted so that the low drilling pressure high-efficiency rock-breaking drill bit can continue to drill the formation to be drilled to the second preset depth; wherein, the second preset depth is greater than the first preset depth, the first working load includes the first torque and the first drilling pressure, and the second working load includes the second torque and the second drilling pressure.

[0018] In one possible implementation, the low-drilling-pressure, high-efficiency rock-breaking method provided in this application has the following first preset calculation formula:

[0019]

[0020] In the formula, The drilling pressure applied to any cutting tooth of the borehole section of a low-pressure, high-efficiency rock-breaking drill bit to the formation to be drilled; This is the first drilling pressure; The torque applied to any cutting tooth of the borehole section of a low-pressure, high-efficiency rock-breaking drill bit to the formation to be drilled; This is the first torque; , , and These are key fitting parameters that characterize the rock properties of the formation to be drilled and the cutting process; is the perimeter of the boundary of the contact area between any cutting tooth and the formation to be drilled; The rake angle corresponding to any cutting tooth; For any cutting tooth, the normal vector of the tooth surface is denoted as . and These are the axial and circumferential unit vectors representing the position of any cutting tooth, respectively. The installation phase angle of any cutting tooth based on the upper crown curve of a low-pressure, high-efficiency rock-breaking drill bit; Let be the radial radius of any cutting tooth; The contact area between any cutting tooth and the formation to be drilled; and / or,

[0021] The second preset calculation formula is:

[0022]

[0023] In the formula, The drilling pressure applied to any reaming tooth of the reaming section of a low-drill-pressure, high-efficiency rock-breaking drill bit to the formation to be drilled. This is the second drilling pressure; The torque applied to any reaming tooth of the reaming section of a low-drill-pressure, high-efficiency rock-breaking drill bit to the formation to be drilled; This is the second torque; , , and These are key fitting parameters that characterize the rock properties of the formation to be drilled and the cutting process; The perimeter of the boundary area between any reaming tooth and the corresponding contact area of ​​the formation to be drilled; The back tilt angle corresponding to any enlarged tooth; For any enlarged tooth, the normal vector of the tooth surface is denoted as ; and These are the axial and circumferential unit vectors of the position of any reaming tooth, respectively; The installation phase angle of the upper crown curve of any reaming tooth based on a low-drill-pressure, high-efficiency rock-breaking drill bit; The radial radius of any of the enlarged teeth; The contact area between any reaming tooth and the formation to be drilled is determined by the following formula:

[0024]

[0025] In the formula, This indicates the depth of penetration per revolution of a low-pressure, high-efficiency rock-breaking drill bit. This refers to the half-angle value of the helical curve cone angle of the reaming blade in a low-drill-pressure, high-efficiency rock-breaking drill bit. The width of the contact zone between any pre-set reaming tooth and the formation to be drilled.

[0026] This application provides a low-pressure drilling method and a high-efficiency rock breaking drill bit. The low-pressure drilling high-efficiency rock breaking drill bit consists of a main body, a drilling section, and a reaming section. The drilling section is located at the end of the main body and has multiple cutting wings on its outer circumferential surface. Each cutting wing is evenly distributed radially and is arc-shaped. Multiple cutting teeth are evenly fixed on the cutting wings along the arc direction. The reaming section is located on the outer circumferential surface of the main body and has a conical spiral structure. The small-diameter end of the reaming section abuts against the drilling section. Multiple reaming teeth are evenly fixed on the reaming section along the spiral direction. The reaming teeth are configured to contact the formation during the drilling process of the main body to convert rotational kinetic energy into axial thrust.

[0027] Thus, during use, pre-breaking rock in the borehole section relieves bottom-hole stress and reduces rock-breaking resistance in the subsequent reaming section. Furthermore, the borehole section's stable contact with the formation via arc-shaped cutting wings suppresses vibration and deflection of the low-pressure-to-drill-force (BPTF) high-efficiency rock-breaking drill bit, enhancing drilling stability. Simultaneously, the conical helical cutting tooth arrangement converts rotational kinetic energy into axial propulsion, enhancing the self-propelled capability of the BPTF high-efficiency rock-breaking drill bit, reducing dependence on external drilling pressure, and achieving the effect of low-pressure-to-drilling. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0029] Figure 1 A schematic diagram of the low-drill-pressure, high-efficiency rock-breaking drill bit provided in this application;

[0030] Figure 2 for Figure 1 Another structural diagram from another angle;

[0031] Figure 3 for Figure 1 Another structural diagram from another angle;

[0032] Figure 4 A schematic diagram of the reaming teeth in the low-drill-pressure, high-efficiency rock-breaking drill bit provided in this application;

[0033] Figure 5 This is a flowchart illustrating the low-drilling-pressure, high-efficiency rock-breaking method provided in this application.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100 - Main body; 110 - Threaded interface;

[0036] 200 - Drilling section; 210 - Cutting blade; 211 - Cutting tooth;

[0037] 300 - Hole enlargement section; 310 - Hole enlargement wing; 311 - Hole enlargement tooth; 3111 - Quarter-spherical section; 3112 - Semi-cylindrical section. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] The terms "first," "second," "third," "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those illustrated or described herein.

[0042] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0043] In the exploration and development of energy resources such as oil, natural gas, and geothermal energy, the drill bit is the core tool for drilling operations, and its performance directly affects drilling efficiency, cost, and safety.

[0044] During the process of breaking rocks at the bottom of a well, the drill bit must overcome the compressive and shear strength of the formation. Traditional drill bits rely on axial drilling pressure and rotational torque provided by external equipment as the energy source for rock breaking. However, with the increase in drilling depth and formation complexity (such as hard rock formations, high-stress layers, or salt gypsum layers), the demand for drilling pressure and torque of conventional drill bits increases significantly, leading to increased load on external equipment and higher drilling costs. In addition, in directional drilling or horizontal well operations, the stability of the drill bit is crucial for wellbore trajectory control. If the drill bit structure design is unreasonable, vibration, deviation, or even stuck pipe accidents can easily occur.

[0045] Therefore, in order to meet the needs of efficient and safe drilling under complex geological conditions, there is an urgent need to provide a drill bit structure that can reduce the dependence on drilling pressure, improve rock breaking efficiency, and ensure stability during the drilling process.

[0046] In view of this, this application provides a low-pressure-to-blow (DBB) high-efficiency rock breaking method and drill bit. The low-pressure-to-blow (DBB) high-efficiency rock breaking drill bit comprises a main body, a drilling section, and a reaming section. The drilling section is located at the end of the main body and has multiple cutting wings on its outer circumferential surface. These cutting wings are evenly distributed radially and are arc-shaped, with multiple cutting teeth evenly fixed along the arc direction. The reaming section is located on the outer circumferential surface of the main body and has a conical spiral structure. The small-diameter end of the reaming section abuts against the drilling section, and multiple reaming teeth are evenly fixed along the spiral direction. These reaming teeth are configured to contact the formation during the drilling process of the main body, converting rotational kinetic energy into axial thrust. Thus, in use, pre-rock breaking by the drilling section unloads bottom-hole stress, reducing the rock-breaking resistance of the subsequent reaming section. Furthermore, the stable contact between the drilling section and the formation through the arc-shaped cutting wings suppresses vibration and deflection of the low-pressure-to-blow (DBB) high-efficiency rock breaking drill bit, enhancing drilling stability. Meanwhile, by using the cutting teeth arrangement of the conical spiral structure, rotational kinetic energy is converted into axial propulsion force, which can enhance the self-propelled capability of the low-pressure, high-efficiency rock-breaking drill bit, reduce dependence on external drilling pressure, and achieve the effect of low-pressure drilling.

[0047] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0048] See Figure 1 The low-pressure, high-efficiency rock-breaking drill bit provided in this application includes a main body 100, a drilling section 200, and a reaming section 300. The drilling section 200 is located at the end of the main body 100. The outer peripheral surface of the drilling section 200 has multiple cutting wings 210, each cutting wing 210 is evenly distributed radially, and each cutting wing 210 is arc-shaped. Multiple cutting teeth 211 are evenly fixed on the cutting wing 210 along the arc direction. The reaming section 300 is located on the outer peripheral surface of the main body 100. The reaming section 300 has a conical spiral structure. The small-diameter end of the reaming section 300 abuts against the drilling section 200. Multiple reaming teeth 311 are evenly fixed on the reaming section 300 along the spiral direction. The reaming teeth 311 are configured to contact the formation during the drilling process of the main body 100 to convert rotational kinetic energy into axial thrust.

[0049] The main body 100 can be cylindrical and serve as a support frame for the low-pressure, high-efficiency rock-breaking drill bit. One end of the main body 100 can be provided with a threaded interface 110 that connects to the drill string, and the other end is fixedly connected to the drilling part 200. The outer circumferential surface of the main body 100 and the reaming part 300 form an integrated structure.

[0050] In practice, the main body 100 has a flow channel inside, which is used to transport drilling fluid to the bottom of the well and carry rock cuttings back out.

[0051] Furthermore, the borehole section 200 is designed as the main rock-breaking component of a low-pressure, high-efficiency rock-breaking drill bit. Multiple cutting wings 210 are evenly distributed on the outer circumferential surface of the borehole section 200, arranged radially and extending outwards from the center of the borehole section 200, forming a petal-like layout. The cutting wings 210 are designed with a smooth, arc-shaped structure; this arc design optimizes stress distribution during rock cutting and reduces cutting vibration.

[0052] On the surface of each cutting blade 210, multiple cutting teeth 211 are uniformly fixed along its arc contour. The cutting teeth 211 are made of polycrystalline diamond composite (PDC) material and have a circular tooth design to provide high hardness and wear resistance. The arrangement angle of the cutting teeth 211 on the cutting blade 210 can be designed according to actual needs. For example, the back tilt angle of the front row of cutting teeth 211 is larger to enhance the attack power; the back tilt angle of the rear row of cutting teeth 211 is smaller to provide better support, thereby achieving a staged rock breaking effect.

[0053] Understandably, when viewed from top to bottom, the cutting teeth 211 that first contact the new rock surface when the low-pressure, high-efficiency rock-breaking drill bit is rotated clockwise are the front row cutting teeth 211. The front row cutting teeth 211 are located at the front end of the cutting blade 210, that is, near the outer edge of the drill bit or the leading edge of rotation. The cutting teeth 211 that follow the front row cutting teeth 211 and contact the rock surface after the front row cutting teeth 211 have initially broken the rock are the rear row cutting teeth 211. The rear row cutting teeth 211 are usually located at the rear end of the cutting blade 210, that is, near the center of the drill bit or the rear of rotation.

[0054] The reaming section 300 is arranged around the outer peripheral surface of the main body 100, and has an overall conical spiral structure. Its small-diameter end is in close contact with the outer edge of the drilling section 200, while its large-diameter end extends towards the threaded interface 110 of the main body 100. The conical spiral structure can be optimized according to fluid dynamics and rock mechanics to facilitate the upward transport of rock cuttings and provide stable lateral support.

[0055] On the helical surface of the reaming section 300, multiple reaming teeth 311 are evenly distributed along the helical direction. The size of the reaming teeth 311 can be smaller than the cutting teeth 211 of the drilling section 200. The reaming teeth 311 are mainly used to trim the well wall and enlarge the wellbore. After the reaming teeth 311 are installed, when the low-pressure drilling high-efficiency rock-breaking drill bit comes into contact with the formation during rotation, the reaming teeth 311 generate a downward axial force. This force is consistent with the drilling direction, thereby partially offsetting the upward reaction force generated during drilling.

[0056] For example, during drilling operations, drilling fluid is injected into the bottom of the well through the internal channels of the main body 100, while the low-pressure-on-drill-force (BPOP) high-efficiency rock-breaking drill bit begins operation under rotary power. The cutting teeth 211 of the borehole section 200 first contact the formation rock at the bottom of the well for preliminary fracturing. This process forms a pre-fracture zone in the central region of the bottom of the well, effectively reducing the overall strength of the rock and achieving a stress unloading effect. At the same time, the borehole section 200, through the stable contact between the arc-shaped cutting wings 210 and the formation, can suppress the vibration and deflection of the BPOP high-efficiency rock-breaking drill bit, enhancing drilling stability.

[0057] Subsequently, as the low-pressure-to-drill-force (LPD) high-efficiency rock-breaking drill bit continues to penetrate deeper, the reaming teeth 311 of the reaming section 300 contact the wellbore. Guided by the helical structure, the force generated by the interaction between the reaming teeth 311 and the formation is decomposed into torsional force and axial force, with the axial force oriented in the same direction as the drilling direction, forming a self-advancing effect. This self-advancing effect can reduce the need for externally applied drilling pressure, for example, in homogeneous soft formations, enabling near-zero external drilling pressure for high-efficiency drilling. Simultaneously, the conical helical structure of the reaming section 300 forms a stable contact interface with the wellbore, providing good guidance and stability in horizontal and directional well drilling, ensuring precise control of the wellbore trajectory.

[0058] The first structure of the enlarged hole portion 300 in the embodiments of this application will be described below.

[0059] In some examples, the enlarged hole portion 300 includes an enlarged hole wing 310, which is disposed on the outer peripheral surface of the main body portion 100. The enlarged hole wing 310 extends spirally along the axial direction of the main body portion 100, and the thickness of the enlarged hole wing 310 decreases sequentially in the direction toward the drilled hole portion 200 to form a conical spiral structure. The enlarged hole wing 310 has a plurality of enlarged hole teeth 311 uniformly fixed along the spiral direction.

[0060] Thus, the single-wing conical spiral structure helps to simplify the manufacturing process.

[0061] Among them, the thickness distribution of the enlarged wing 310 exhibits a progressive thinning characteristic along the axial direction of the main body 100 and towards the drilled part 200. That is, the wing thickness is the smallest near the connection of the drilled part 200 and the wing thickness is the largest far away from the drilled part 200. This thickness change is connected by a smoothly transitioning curved surface, so that the entire enlarged wing 310 naturally forms a conical spiral profile.

[0062] When the drill bit rotates and drills, the conical spiral structure of the reaming blade 310 first stabilizes the drill bit posture through the thicker upper region, and then the gradually thinning lower region intervenes after the pre-rock breaking is completed in the borehole section 200. The force generated by the interaction between the reaming teeth 311 and the well wall is decomposed into a radial constraint component and an axial propulsion component, in which the axial component is consistent with the drilling direction, effectively compensating for the drilling pressure requirement.

[0063] The enlarged flange 310 and the borehole section 200 form a smooth transition arc surface at the connection point, which avoids stress concentration and ensures that the flow path of rock cuttings from the bottom of the well to the annulus is continuous and unobstructed.

[0064] The working surface of the reaming wing 310 is provided with mounting grooves. Multiple reaming teeth 311 are embedded and firmly fixed in these grooves at equal helical angle intervals. The cutting surface of the reaming teeth 311 faces the tangential direction of the drill bit rotation, and its mounting angle is set according to the curvature of the helix, ensuring that the reaming teeth 311 at different axial positions can form effective contact with the well wall.

[0065] The second structure of the enlarged hole portion 300 in the embodiments of this application will be described below.

[0066] See Figures 1 to 3 In some other embodiments, the enlarged hole portion 300 includes at least two enlarged hole wings 310, each enlarged hole wing 310 being evenly distributed on the outer peripheral surface of the main body portion 100. The enlarged hole wings 310 are arc-shaped, and the thickness of the enlarged hole wings 310 decreases sequentially along the direction toward the drilling portion 200. Moreover, each enlarged hole wing 310 is oriented in the same direction to form a conical spiral structure. Multiple enlarged hole teeth 311 are evenly fixed on the enlarged hole wings 310 along the arc direction.

[0067] In this embodiment, the reaming section 300 adopts a multi-wing cooperative structure design. The multi-wing conical spiral structure can enhance the drill bit's ability to resist lateral vibration. During the reaming process, the orderly relay of each wing body continuously converts the rotational motion into an effective axial propulsion component, which significantly reduces the external drilling pressure requirement while effectively maintaining the wellbore quality and wellbore trajectory accuracy.

[0068] Each reaming wing 310 maintains the same spiral orientation in space; that is, the starting and ending ends of all reaming wings 310 follow a consistent rotational trend in the circumferential direction. The thickness distribution of each reaming wing 310 exhibits a regular variation characteristic, with the wing thickness gradually decreasing from the upper end away from the drilled portion 200 to the lower end closer to the drilled portion 200. Thus, when multiple reaming wings 310 are combined, this unidirectional arrangement forms a continuous conical spiral profile on a macroscopic scale.

[0069] On the working surface of the reaming blade 310, multiple tooth seats are provided along the extension path of its arc contour. The reaming teeth 311 are firmly embedded in these tooth seats by interference fit or welding. The tip height and cutting angle are adaptively adjusted according to the curvature of the arc to ensure that each reaming tooth 311 can contact the well wall in sequence and form a continuous cutting trajectory during the rotation of the drill bit.

[0070] In a specific example, the height of each reaming tooth 311 on the same reaming wing 310 varies along a radial gradient to form graded cutting.

[0071] Specifically, radial refers to the direction extending outward from the central axis of the main body 100 to the contact surface of the well wall. The protrusion height of each enlarging tooth 311 gradually increases from the inner diameter side to the outer diameter side, forming a stepped profile that is lower on the inside and higher on the outside.

[0072] The inner diameter region refers to the part of the reamer 310 that is close to the central axis of the drill bit, while the outer diameter region refers to the part of the reamer 310 that is far from the central axis and close to the contact edge of the well wall.

[0073] During actual drilling, when the drill bit rotates and contacts the well wall, the radial height difference of each reaming tooth 311 helps to form an effective cuttings diversion channel, achieve layered and graded rock breaking effect, avoid repeated crushing caused by the accumulation of cuttings between the teeth, and improve cuttings removal.

[0074] In other embodiments, the enlarged tooth 311 is semi-cylindrical (not shown in the figure).

[0075] Among them, the semi-cylindrical reaming tooth 311 has a smooth arc-shaped working surface. Its cross-section is semi-circular, extending axially to form a columnar structure. The outer surface is precision polished to reduce the friction coefficient with the rock. Its smooth contour can continuously and stably cut into the rock, reducing impact load. At the same time, the semi-cylindrical structure has high structural strength and excellent impact resistance, which can meet the requirements of long-life drilling operations in highly abrasive formations.

[0076] In other examples, such as Figure 4 As shown, the expanded hole tooth 311 is horseshoe-shaped.

[0077] It is understandable that the horseshoe-shaped enlarged tooth 311 may include Figure 4 The device consists of a quarter-spherical portion 3111 and a semi-cylindrical portion 3112 arranged sequentially. The quarter-spherical portion 3111 is a quarter-sphere structure, and the semi-cylindrical portion 3112 is a half-cylindrical structure. During tooth arrangement, the semi-cylindrical portion 3112 is mounted on the reaming wing 310, while the quarter-spherical portion 3111 faces outward. The planar portion formed by the two portions serves as the cutting surface, enabling continuous and stable cutting into the rock. This tooth arrangement orientation prevents interference from straight edges cutting the strata, resulting in a simple tooth arrangement with good impact resistance.

[0078] To improve the adaptability of low-pressure, high-efficiency rock-breaking drill bits under different well diameter conditions, in a specific example, the number of reaming wings 310 is 4-9; and / or, the pitch between two adjacent reaming wings 310 is 60-100 cm.

[0079] In this embodiment, the number of enlarged wing 310 is set to 4-9, for example, 4, 5, 6, 7, 8 or 9, to meet the requirements of drilling fluid flow section, while ensuring the uniform strength distribution of the overall structure of the low drilling pressure high efficiency rock breaking drill bit.

[0080] Furthermore, by setting the pitch between two adjacent reaming blades 310 to 60-100 cm, where the axial distance between adjacent reaming blades 310 is the pitch, the pitch can be 60 cm, 65 cm, 70 cm, 75 cm, 80 cm, 85 cm, 90 cm, 95 cm or 100 cm, it is ensured that the reaming teeth 311 can form a continuous cutting trajectory during rotation, avoiding cutting blind spots, and providing sufficient flow space for rock cuttings to return.

[0081] In some embodiments, the drilling portion 200 includes a cone portion, a nose portion, a shoulder portion, and a diameter-holding portion arranged sequentially; the cone portion, nose portion, shoulder portion, and diameter-holding portion together form a cover cavity with an opening on one side, and the cover cavity matches the main body portion 100; a portion of the main body portion 100 is located in the cover cavity, and any cutting wing 210 is simultaneously provided on the cone portion, nose portion, shoulder portion, and diameter-holding portion.

[0082] In this embodiment, the lower region of the main body 100, i.e. the end region away from the threaded interface 110, is embedded into the cover cavity and is firmly connected by interference fit or welding to form a drill bit front end structure with high overall strength and uniform stress distribution.

[0083] The cutting blade 210 starts from the cone section, continuously crosses the nose and shoulder sections, and finally extends to the gauge section, forming a complete arc-shaped blade that runs through four sections. Among them, the cone section is located at the foremost end of the borehole section 200, with a pointed cone-shaped transition structure. Its surface is arranged with a small number of highly aggressive cutting teeth 211, which mainly undertake the initial rock breaking function. The nose section is immediately behind the cone section, with the radius of curvature gradually increasing to form a smooth convex arc surface. The density of cutting teeth 211 on it is higher than that on the cone section, which is responsible for expanding the breaking area. The shoulder section connects the nose section and the gauge section, and adopts a gently transitioning inclined surface design. The cutting teeth 211 are densely arranged and the back slope angle is reduced, which mainly undertakes the high-load rock breaking task. The gauge section is located on the outermost side of the borehole section 200. Its surface is equipped with wear-resistant gauge blocks and cutting teeth 211. The diameter is consistent with the designed wellbore size to ensure the wellbore is regular and the drill bit is stably centered.

[0084] In some examples, the length of the reamed portion 300 is 30-50 cm; and / or, the outer diameter of the drilled portion 200 is 60%-80% of the diameter of the large-diameter end of the reamed portion 300, and the difference between the outer diameter of the drilled portion 200 and the diameter of the small-diameter end of the reamed portion 300 is 0.2-0.4 mm.

[0085] It should be noted that the outer diameter of the drilled part 200 is the same as the outer diameter of the diameter-protecting part of the drilled part 200.

[0086] By setting the length of the reaming section 300 to 30-50 cm, it is ensured that the reaming blade 310 can form a complete conical helical structure, providing sufficient axial propulsion force conversion area, while avoiding the problems of increased torque resistance and poor cuttings transport caused by excessive length. For example, the length of the reaming section 300 is 30 cm, 32 cm, 34 cm, 36 cm, 40 cm, 41 cm, 43 cm, 44 cm, 45 cm, 47 cm, 48 cm, 49 cm, or 50 cm.

[0087] By setting the outer diameter of the borehole section 200 to be 60%-80% of the diameter of the large-diameter end of the reaming section 300, the borehole section 200 can efficiently complete rock breaking in the central area, while reserving a reasonable annular space for the reaming section 300 to ensure smooth upward return of rock cuttings. For example, the outer diameter of the borehole section 200 can be 60%, 63%, 65%, 66%, 67%, 68%, 69%, 70%, 72%, 75%, 78%, 79%, or 80% of the diameter of the large-diameter end of the reaming section 300.

[0088] Furthermore, by setting the difference between the outer diameter of the borehole section 200 and the diameter of the small-diameter end of the reaming section 300 to 0.2-0.4 mm, it is possible to prevent drill cuttings from accumulating at the connection point and forming mud bags during drilling, and to ensure that the borehole section 200 and the reaming section 300 form a continuous stress relief path during rock breaking operations. For example, the difference can be 0.2 mm, 0.24 mm, 0.26 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.34 mm, 0.36 mm, 0.38 mm, or 0.4 mm.

[0089] Through the aforementioned dimensional matching relationship, on the one hand, it is beneficial for the low-pressure, high-efficiency rock-breaking drill bit to exhibit a stepped rock-breaking characteristic during operation. That is, the borehole section 200 first forms a pre-fracture zone in the central area of ​​the bottom of the well, reducing the overall strength of the rock; then the small-diameter end of the reaming section 300 contacts the pre-fractured rock. Due to the precise control of the dimensional difference, the reaming teeth 311 can act on the weakened rock at a suitable cutting depth, continuously converting rotational kinetic energy into axial propulsion force; finally, the large-diameter end of the reaming section 300 completes the wellbore dressing, and its diameter matches the designed wellbore size, ensuring the quality of the well wall.

[0090] On the other hand, it helps to optimize the center of gravity of the low-pressure, high-efficiency rock-breaking drill bit and reduce the amplitude of lateral vibration. For example, in the formation of alternating soft and hard strata, the size matching of the borehole section 200 and the reaming section 300 can adaptively adjust the rock-breaking depth and prevent the drill bit from jumping or sticking due to instantaneous resistance changes.

[0091] In some embodiments, the main body 100 is provided with a plurality of water holes; there are 2-4 water holes between two adjacent expansion wings 310.

[0092] In this way, the water jet can ensure that the area between adjacent reamers 310 can be adequately flushed with drilling fluid, preventing rock cuttings from accumulating and forming mud bags. At the same time, the water jet can create a local negative pressure zone in front of the reamer teeth 311, enhancing the rock cuttings removal effect.

[0093] During drilling, drilling fluid is ejected at high speed from the internal flow channel of the main body 100 through the water hole. It first carries away the broken rock cuttings in the borehole section 200. Then, under the guiding action of the reaming wing 310, the fluid flows upward along the spiral path, forming a continuous cleaning zone covering the entire reaming area.

[0094] In practice, the water inlet can be positioned to avoid the high-stress area at the root of the expansion flange 310, ensuring structural strength while allowing the coolant flow to directly act on the working area of ​​the tooth where cutting heat is concentrated.

[0095] For example, the number of water holes between two adjacent expansion fins 310 can be 2, 3 or 4, and this application embodiment does not limit this.

[0096] See Figure 5 This application also provides a low-drill-pressure, high-efficiency rock-breaking method, which uses a low-drill-pressure, high-efficiency rock-breaking drill bit as described in any of the above embodiments to drill a hole in the formation to be drilled. The method includes:

[0097] S101. According to the first preset calculation formula, determine the first working load of all cutting teeth 211 of the low drilling pressure high efficiency rock breaking drill bit on the formation to be drilled, and according to the second preset calculation formula, determine the second working load of all reaming teeth 311 of the low drilling pressure high efficiency rock breaking drill bit on the formation to be drilled.

[0098] Here, the first preset calculation formula can determine the first working load of each cutting tooth 211 under stable drilling state by comprehensively considering the geometric parameters of the cutting tooth 211, the formation compressive strength and the rotational dynamics of the drill bit. This load includes the axial drilling pressure component and the circumferential torque component.

[0099] The second preset calculation formula can take into account the special structure of the reaming tooth 311, the conical spiral geometry, the well wall contact pressure distribution and the rock lateral resistance, and calculate the second working load of each reaming tooth 311, which also includes drilling pressure and torque components.

[0100] S102. Under the action of external preset drilling pressure and external preset torque, the formation to be drilled is drilled to the first preset depth by a low-drilling-pressure high-efficiency rock-breaking drill bit.

[0101] This step can be understood as follows: in the initial drilling stage of a low-pressure, high-efficiency rock-breaking drill bit, conventional external drilling pressure and torque parameters are used to allow the drill bit to drill to a specific depth in the formation to be drilled, so as to establish an initial wellbore profile that meets the actual design requirements.

[0102] The embodiments of this application do not limit the specific amounts of external preset drilling pressure and external preset torque, as long as they can ensure that the low-pressure, high-efficiency rock-breaking drill bit can be driven to drill.

[0103] The first preset depth can be 1-2 m, such as 1 m, 1.2 m, 1.5 m, 1.8 m or 2 m.

[0104] S103. Based on the first working load and the second working load, adjust the external drilling pressure and the external torque to enable the low drilling pressure high-efficiency rock-breaking drill bit to continue drilling the formation to be drilled to the second preset depth; wherein, the second preset depth is greater than the first preset depth, the first working load includes the first torque and the first drilling pressure, and the second working load includes the second torque and the second drilling pressure.

[0105] In other words, once the initial wellbore design is completed, based on the working load data obtained from these two sets of preset calculation formulas, the drill bit is put into a low-pressure drilling mode by adjusting the external drilling pressure and external torque application. In this mode, the axial component force generated by the 300° conical helical structure of the reamer during rotation can effectively compensate for part of the drilling pressure requirement, allowing the externally applied mechanical drilling pressure to be lower than the value required by conventional drill bits.

[0106] In some examples, the first preset calculation formula is:

[0107]

[0108] In the formula, The drilling pressure applied to any cutting tooth 211 of the borehole section 200 of the low-drilling-pressure, high-efficiency rock-breaking drill bit to the formation to be drilled. This is the first drilling pressure; The torque applied to any cutting tooth 211 of the borehole section 200 of the low-pressure, high-efficiency rock-breaking drill bit to the formation to be drilled; This is the first torque; , , and These are key fitting parameters that characterize the rock properties of the formation to be drilled and the cutting process; Let be the perimeter of the boundary of the contact area between any cutting tooth 211 and the formation to be drilled; The rake angle corresponding to any cutting tooth 211; For any cutting tooth 211, the tooth surface normal vector is denoted by ; and These are the axial and circumferential unit vectors of the position of any cutting tooth 211, respectively; The installation phase angle of any cutting tooth 211 based on the upper crown curve of a low-pressure, high-efficiency rock-breaking drill bit; Let be the radial arrangement radius of any cutting tooth 211; The contact area between any cutting tooth 211 and the formation to be drilled.

[0109] It should be noted that the design of the drilling section 200 in this embodiment can adopt a conventional PDC drill bit in the prior art; That is, the contact area between any cutting tooth 211 and the formation to be drilled can be obtained by the calculation formula in the prior art, which will not be repeated in the embodiments of this application.

[0110] In other embodiments, the second preset calculation formula is:

[0111]

[0112] In the formula, The drilling pressure applied to the formation to be drilled by any of the reaming teeth 311 of the reaming section 300 of the low-drilling-pressure, high-efficiency rock-breaking drill bit. This is the second drilling pressure; The torque applied to the formation to be drilled by any of the reaming teeth 311 of the reaming section 300 of the low-drilling-pressure, high-efficiency rock-breaking drill bit. This is the second torque; , , and These are key fitting parameters that characterize the rock properties of the formation to be drilled and the cutting process; The perimeter of the boundary area between any enlarged hole tooth 311 and the corresponding contact area of ​​the formation to be drilled; The back tilt angle corresponding to any enlarged tooth 311; For any enlarged tooth 311, the normal vector of the tooth surface is denoted by the tooth surface. and These are the axial and circumferential unit vectors of the position of any enlarged tooth 311, respectively; The installation phase angle of the upper crown curve of any reaming tooth 311 based on the low drilling pressure high efficiency rock breaking drill bit; The radial arrangement radius of any of the enlarged teeth 311; The contact area between any reaming tooth 311 and the formation to be drilled is determined by the following formula:

[0113]

[0114] In the formula, This indicates the depth of penetration per revolution of a low-pressure, high-efficiency rock-breaking drill bit. The half-angle value of the helical curve cone angle of the reaming blade 310 of the low-drilling-pressure, high-efficiency rock-breaking drill bit; The width of the contact zone between any pre-set reaming tooth 311 and the formation to be drilled.

[0115] In this embodiment of the application, taking the reaming section 300 as having four reaming wings 310, reaming teeth 311 being semi-cylindrical, the length of the reaming section 300 being 30 cm, and the diameter of the large-diameter end of the reaming section 300 being 80 mm as an example, the first working load of all the cutting teeth 211 of the drilling section 200 of the low-drill-pressure high-efficiency rock-breaking drill bit is calculated using the first preset calculation formula, and the second working load of all the reaming teeth 311 of the reaming section 300 of the low-drill-pressure high-efficiency rock-breaking drill bit is calculated using the second preset calculation formula, and then summed to obtain the overall working load of the low-drill-pressure high-efficiency rock-breaking drill bit.

[0116] The first drilling pressure is 2.4 kN, the first torque is 33.3 N·m, the second drilling pressure is -4.7 kN, and the second torque is 85.6 N·m; the overall drilling pressure of the low drilling pressure high-efficiency rock breaking drill bit is -2.3 kN, and the overall torque is 118.9 N·m.

[0117] It can be seen that the directions of the first torque and first drill pressure of all cutting teeth 211 at the borehole section 200 are opposite to the drilling direction, indicating that in the initial stage of drilling with the low drill pressure high-efficiency rock-breaking drill bit, external drill pressure needs to be applied to overcome this reverse resistance. Furthermore, due to the conical helical structure of the reaming section 300, an axial force is generated in the same direction as the drilling direction. This force not only effectively counteracts the reverse force generated at the top but also makes the final resultant force of the entire drill bit (resultant force value -2.3 kN) in the same direction as the drilling direction. Thus, in the process of the low drill pressure high-efficiency rock-breaking drill bit drilling the formation from the first preset depth to the second preset depth, no continuous external drill pressure is required, achieving a self-propelled effect.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A low-drill-pressure, high-efficiency rock-breaking method, characterized in that, include: According to the first preset calculation formula, the first working load of all cutting teeth (211) of the low drilling pressure high efficiency rock breaking drill bit on the formation to be drilled is determined, and according to the second preset calculation formula, the second working load of all reaming teeth (311) of the low drilling pressure high efficiency rock breaking drill bit on the formation to be drilled is determined. Under the action of external preset drilling pressure and external preset torque, the formation to be drilled is drilled to the first preset depth by the low drilling pressure high efficiency rock breaking drill bit; Based on the first working load and the second working load, the external drilling pressure and external torque are adjusted so that the low drilling pressure high-efficiency rock-breaking drill bit continues to drill the formation to be drilled to a second preset depth; wherein, the second preset depth is greater than the first preset depth, the first working load includes a first torque and a first drilling pressure, and the second working load includes a second torque and a second drilling pressure; The first preset calculation formula is: In the formula, The drilling pressure applied to the formation to be drilled by any cutting tooth (211) of the borehole section (200) of the low-drilling-pressure, high-efficiency rock-breaking drill bit; This is the first drilling pressure; The torque applied to the formation to be drilled by any cutting tooth (211) of the borehole section (200) of the low-pressure, high-efficiency rock-breaking drill bit; This is the first torque; , , and These are key fitting parameters that characterize the rock properties of the formation to be drilled and the cutting process; Let be the perimeter of the boundary of the contact area between any cutting tooth (211) and the formation to be drilled; Let be the back rake angle corresponding to any cutting tooth (211); Let be the tooth surface normal vector corresponding to any cutting tooth (211); and , respectively, are the axial and circumferential unit vectors of the position of any cutting tooth (211); The installation phase angle of any cutting tooth (211) is based on the upper crown curve of a low-pressure, high-efficiency rock-breaking drill bit; Let be the radial radius of any cutting tooth (211); The contact area between any cutting tooth (211) and the formation to be drilled; and / or, The second preset calculation formula is: In the formula, For the reaming section (300) of a low-drilling-pressure, high-efficiency rock-breaking drill bit, any reaming tooth (311) applies drilling pressure to the formation to be drilled; This is the second drilling pressure; The torque applied to the formation to be drilled by any of the reaming teeth (311) of the reaming section (300) of the low-drilling-pressure, high-efficiency rock-breaking drill bit; This is the second torque; , , and These are key fitting parameters that characterize the rock properties of the formation to be drilled and the cutting process; Let be the perimeter of the boundary area between any reaming tooth (311) and the corresponding contact area of ​​the formation to be drilled; The back tilt angle corresponding to any enlarged tooth (311); Let be the tooth surface normal vector corresponding to any enlarged tooth (311); and These are the axial and circumferential unit vectors of the position of any reaming tooth (311); The installation phase angle of any reaming tooth (311) is based on the upper crown curve of a low-drill-pressure, high-efficiency rock-breaking drill bit; Let be the radial arrangement radius of any of the enlarged teeth (311); The contact area between any reaming tooth (311) and the formation to be drilled is determined by the following formula: In the formula, This indicates the depth of penetration per revolution of a low-pressure, high-efficiency rock-breaking drill bit. The half-angle value of the spiral curve cone angle of the reaming blade (310) of the low-drilling-pressure, high-efficiency rock-breaking drill bit; The width of the contact zone between any pre-set reaming tooth (311) and the formation to be drilled.

2. A low-pressure, high-efficiency rock-breaking drill bit, characterized in that, Drilling a hole in the formation to be drilled using the low drilling pressure and high-efficiency rock breaking method described in claim 1 includes: Main body (100); A drilling section (200) is provided at the end of the main body (100). The outer peripheral surface of the drilling section (200) has a plurality of cutting wings (210). Each cutting wing (210) is evenly distributed radially and is arc-shaped. A plurality of cutting teeth (211) are evenly fixed on the cutting wing (210) along the arc direction. The reaming section (300) is disposed on the outer peripheral surface of the main body (100). The reaming section (300) has a conical spiral structure. The small diameter end of the reaming section (300) abuts against the drilling section (200). The reaming section (300) has a plurality of reaming teeth (311) uniformly fixed along the spiral direction. The reaming teeth (311) are configured to contact the formation during the drilling process of the main body (100) to convert rotational kinetic energy into axial thrust.

3. The low-drilling-pressure, high-efficiency rock-breaking drill bit according to claim 2, characterized in that, The enlarged hole section (300) includes an enlarged hole wing (310), which is disposed on the outer peripheral surface of the main body section (100). The enlarged hole wing (310) extends spirally along the axial direction of the main body section (100), and the thickness of the enlarged hole wing (310) decreases sequentially in the direction toward the drilled hole section (200) to form a conical spiral structure. The enlarged hole wing (310) has a plurality of enlarged hole teeth (311) uniformly fixed along the spiral direction.

4. The low-drilling-pressure, high-efficiency rock-breaking drill bit according to claim 2, characterized in that, The enlarged hole section (300) includes at least two enlarged hole wings (310), each of the enlarged hole wings (310) being evenly distributed on the outer peripheral surface of the main body section (100). The enlarged hole wings (310) are arc-shaped, and the thickness of the enlarged hole wings (310) decreases sequentially along the direction toward the drilled hole section (200). The enlarged hole wings (310) are oriented in the same direction to form a conical spiral structure. The enlarged hole wings (310) are evenly arranged with a plurality of enlarged hole teeth (311) along the spiral extension path.

5. The low-drilling-pressure, high-efficiency rock-breaking drill bit according to claim 4, characterized in that, The height of each of the reaming teeth (311) on the same reaming blade (310) varies radially in a gradient to form graded cutting; and / or, The enlarged tooth (311) is semi-cylindrical or horseshoe-shaped.

6. The low-drilling-pressure, high-efficiency rock-breaking drill bit according to claim 4, characterized in that, The number of the enlarged aperture wings (310) is 4-9; and / or, The pitch between two adjacent expansion wings (310) is 60-100 cm.

7. The low-drilling-pressure, high-efficiency rock-breaking drill bit according to claim 4, characterized in that, The main body (100) is provided with a plurality of water holes; there are 2-4 water holes between two adjacent expansion wings (310).

8. The low-drilling-pressure, high-efficiency rock-breaking drill bit according to any one of claims 2 to 7, characterized in that, The length of the enlarged portion (300) is 30-50 cm; and / or, The outer diameter of the drilled portion (200) is 60%-80% of the diameter of the large diameter end of the reamed portion (300), and the difference between the outer diameter of the drilled portion (200) and the diameter of the small diameter end of the reamed portion (300) is 0.2-0.4 mm.

9. The low-pressure, high-efficiency rock-breaking drill bit according to any one of claims 2 to 7, characterized in that, The drilled section (200) includes a cone section, a nose section, a shoulder section and a diameter-protecting section arranged in sequence; The cone, nose, shoulder, and diameter-protecting portion together form a cover cavity with an opening on one side, and the cover cavity matches the main body (100); a portion of the main body (100) is located inside the cover cavity, and the cutting wing (210) is simultaneously disposed on the cone, nose, shoulder, and diameter-protecting portion.

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