A high-stability PDC drill bit suitable for soft and hard interlaced formations

Abstract

The present invention provides a high-stability PDC drill bit suitable for soft and hard interlaced strata, and relates to the technical field of oil and gas resource exploration, including a drill bit body, and the crown of the drill bit body is provided with five cutting blades along the circumferential surface; the five cutting blades include three main blades and two auxiliary blades, and are distributed in the manner of main blade, auxiliary blade, main blade, auxiliary blade, and main blade, and are distributed in the azimuths of 0°, 70°, 140°, 225°, and 279°. The present invention, by designing sharp circular plane teeth, takes into account the bite-in ability of the sharp chip teeth and the impact resistance of the circular teeth and the chip-resisting ability of the triangular teeth, so that the PDC drill bit can play the advantage of high drilling speed when drilling in medium-soft homogeneous strata, and when encountering a hard rock interlayer with a small thickness, the height difference setting between the sharp circular teeth and the circular teeth can control the bit bite-in depth, balance the cutting depth in different strata, maintain the stability during drilling, and extend the service life of the drill bit.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas resource exploration, and in particular to a high-stability PDC drill bit suitable for soft and hard alternating strata. Background Art

[0002] PDC (PDC is the abbreviation of PolyCrystalline Diamond Compact) drill bits are important tools for the efficient development of oil and gas. PDC drill bits are usually one of the most important tasks before drilling. By analyzing the formation rock characteristics of the target well in advance and collecting logging data from adjacent wells to calculate and predict the rock mechanical characteristics, the different details of the PDC drill bit are finally optimized based on the established anti-drilling parameter profile, including the number of blades, crown shape, and cutting tooth shape of the drill bit.

[0003] At present, tight gas drilling operations often encounter soft and hard interlaced formations such as sandstone intercalated with mudstone or shale. Conventional PDC drill bits vibrate violently when drilling in the above-mentioned formations due to the influence of instantaneous unbalanced force, and cause drill bit tooth breakage, wear, abnormal shedding of diamond layer, etc. Ultimately, the drill bit fails and the drill is started prematurely, which reduces the rock breaking efficiency and rock breaking stability of the drill bit and makes it difficult to meet the requirements of efficient drilling.

[0004] For heterogeneous and difficult-to-drill formations, in order to extend the service life of the drill bit and improve its aggressiveness, a double-row tooth design is usually adopted. However, the function of most of the second-row auxiliary teeth is to protect the main teeth, and the problem that the drill bit still needs to maintain its drilling ability after the main teeth lose their cutting ability due to severe wear or tooth collapse is not considered. At the same time, the existing designs mainly use conventional circular teeth, pointed teeth and triangular teeth, among which circular teeth have the advantages of anti-collapse and wear resistance, pointed teeth have a high ability to eat into rocks, and triangular teeth have good impact resistance. However, PDC drill bits using the three types of cutting teeth have limited speed-up effect and stability, and have a technical defect of a narrow formation adaptability range.

[0005] To this end, the present invention provides a high-stability PDC drill bit suitable for soft and hard interlaced formations. Summary of the invention

[0006] The higher the yield point, the lower the yield point, the smaller the yield point, and the shorter the yield point, the higher the yield point.PDC drill bits have become more and more popular with consumers. The popularity of PDC drill bits has increased, and it is one of the fastest and most popular drill bits in the world. It has a long history of development, and has won great reputation in the industry. The PDC drill bits have been widely used in the industry for a long time, and have been widely used in the industry for a long time.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A high-stability PDC drill bit suitable for soft and hard interlaced formations, comprising: a drill bit body, the bottom end of the drill bit body having a crown of the drill bit body, the top of the drill bit body being fixedly connected with a drill bit thread, characterized in that: the crown of the drill bit body is provided with five cutting blades along the circumferential surface;

[0009] The five cutting blades include three main blades and two auxiliary blades, and are distributed in the manner of main blade, auxiliary blade, main blade, auxiliary blade, and main blade, and are distributed in the directions of 0°, 70°, 140°, 225°, and 279°;

[0010] The cutting blade has a gauge section and a cutting blade section. The cutting blade section is close to the head end of the crown of the drill body. The cutting blade section is provided with a main cutting tooth and an auxiliary cutting tooth along the rotation direction of the drill body when the drill body is working. The main cutting tooth is located in front of the auxiliary cutting tooth along the rotation direction of the drill body when the drill body is working. The gauge section is provided with a conical cutting tooth and a circular cutting tooth.

[0011] The main cutting teeth are composed of a plurality of circular cutting teeth;

[0012] The auxiliary cutting teeth are composed of one or more limiting teeth and a plurality of sharp circular plane cutting teeth.

[0013] Preferably, the main blade wing and the auxiliary blade wing both adopt a 4°-12° spiral structure.

[0014] Preferably, the main blade wing and the auxiliary blade wing both adopt a 4°-10° spiral structure.

[0015] Preferably, the main cutting teeth and the auxiliary cutting teeth are provided with a height difference, and the height difference between the main cutting teeth and the auxiliary cutting teeth is arithmetic progression, and the height difference between the main cutting teeth and the auxiliary cutting teeth gradually decreases from the central axis of the drill body to the diameter protection direction;

[0016] The rear chamfer of the pointed circular plane cutting teeth increases equidistantly from the central axis of the drill body to the diameter-preserving direction.

[0017] Preferably, an inclined section is provided between the gauge-guarding section and the neck of the drill bit body, and an inverted eye tooth is fixedly mounted on the inclined surface of the inclined section.

[0018] Preferably, the inverted eye teeth are a combination of conical cutting teeth and circular flat teeth.

[0019] Preferably, the inverted eye teeth are composed of two conical cutting teeth and two circular plane teeth, and the conical cutting teeth and the circular plane teeth are arranged alternately.

[0020] Preferably, the pointed circular plane cutting tooth is cylindrical as a whole, and the side surface of the pointed circular plane cutting tooth has an inclined first plane and a second plane, and the first plane and the second plane are symmetrical with the axial section of the pointed circular plane cutting tooth, and the angle β between the intersecting ridges of the first plane and the second plane and the top surface of the pointed circular plane cutting tooth is 90°-120°.

[0021] Preferably, a water hole is provided on the crown of the drill bit body and between the cutting blades.

[0022] Preferably, at least three pointed circular plane cutting teeth are arranged among the auxiliary cutting teeth.

[0023] The present invention provides a high-stability PDC drill bit suitable for soft and hard interlaced formations. It has the following beneficial effects:

[0024] 1. The present invention takes into account the cutting ability of the pointed cutting teeth, the impact resistance of the round teeth, and the chipping resistance of the triangular teeth through the design of the pointed round flat teeth, so that the PDC drill bit can take advantage of the high drilling speed when drilling in medium-soft homogeneous formations. When drilling in hard rock interlayers with a small thickness, the height difference setting between the pointed round teeth and the round teeth can control the cutting depth of the drill bit, and balance the cutting depth in different formations to maintain the stability during drilling; when the drill bit encounters multiple hard rock interlayers, the main cutting teeth of the drill bit are affected by the instantaneous impact force and excessive wear or chipping occurs. Due to the height difference design, the pointed round flat cutting teeth are retained, the arc-shaped wide chip edge has a strong ability to eat rocks, the pointed round flat cutting teeth take on the main cutting task, and the service life of the drill bit is extended.

[0025] 2. The present invention adopts asymmetric blades (five cutting blades are arranged along the circumferential surface of the crown of the drill bit body, the five cutting blades include three main blades and two auxiliary blades, and are distributed in the manner of main blade, auxiliary blade, main blade, auxiliary blade, main blade, and in the azimuths of 0°, 70°, 140°, 225°, and 279°) and spiral blades (both the main blade and the auxiliary blade adopt a spiral structure) to reduce the lateral and stick-slip vibrations of the drill bit caused by underbalanced force, and maintain high stability of the drill bit when drilling soft and hard alternating formations.

[0026] 3. The present invention ensures the borehole quality from two aspects of breaking rock pieces and repairing the well wall by staggeredly arranging conical cutting teeth and circular plane teeth on the diameter protection section, thereby ensuring the smoothness of short tripping operation and being able to well realize the improvement of drill bit footage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A front view of a high-stability PDC drill bit suitable for soft and hard interlaced formations proposed by the present invention;

[0028] Figure 2This is an end view of a high-stability PDC drill bit suitable for soft and hard interlaced formations proposed by the present invention;

[0029] Figure 3 A three-dimensional view of the end of a high-stability PDC drill bit suitable for soft and hard interlaced formations proposed by the present invention;

[0030] Figure 4 A three-dimensional schematic diagram of a sharp round plane cutting tooth of a high-stability PDC drill bit suitable for soft and hard interlaced formations proposed by the present invention;

[0031] Figure 5 This is a schematic diagram of the height difference design of the main cutting teeth and the auxiliary cutting teeth of a high-stability PDC drill bit suitable for soft and hard interlaced formations proposed by the present invention to control the penetration depth.

[0032] Among them, 1, drill body; 101, neck; 102, crown; 103, water eye; 2, drill thread; a, b, c, d, e represent five cutting blades, among which, a, c, e represent main blades; b, d represent auxiliary blades; 1a, diameter protection section; 1b, cutting wing section; 1c, inclined section; g, first plane; h, second plane. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1:

[0035] like Figure 1-Figure 5 As shown, an embodiment of the present invention provides a high-stability PDC drill bit suitable for soft and hard alternating formations, including: a drill bit body 1, the bottom end of the drill bit body 1 has a crown 102 of the drill bit body, the end of the crown 102 is semi-spherical, and the top of the drill bit body 1 is fixedly connected with a drill bit thread 2, and the drill bit thread 2 is connected to a power drill so that the power equipment can drive the drill bit body 1 to rotate and move downward to perform drilling operations.

[0036] The crown 102 of the drill body 1 is provided with five cutting blades a, b, c, d, and e along the circumferential surface. The five cutting blades include three main blades and two auxiliary blades, and are distributed in the manner of main blade a, auxiliary blade b, main blade c, auxiliary blade d, and main blade e, and are distributed in the orientations of 0°, 70°, 140°, 225°, and 279°. The angles between two adjacent cutting blades are 70°, 70°, 85°, and 54°.

[0037] like Figure 2 As shown in , the three main blades and two auxiliary blades are distributed in a beak-shaped complementary form.

[0038] The five cutting blades a, b, c, d, and e are designed in this asymmetric form, so that the underbalanced force in the cutting process is close to 0, reducing the vibration of the PDC drill bit, improving the overall stability of the PDC drill bit, preventing uneven force and angle tilt when the drill bit collides with the bottom of the well, and balancing the force distribution of the blades at the bottom of the well.

[0039] The cutting blade comprises a gauge section 1a and a cutting wing section 1b. The cutting wing section 1b is close to the head end of the crown 102 of the drill bit body. The cutting wing section 1b is provided with a main cutting tooth 1b1 and an auxiliary cutting tooth 1b2 along the rotation direction of the drill bit body 1 when the drill bit body 1 is working. In addition, along the rotation direction of the drill bit body 1 when the drill bit body 1 is working, the main cutting tooth 1b1 is located in front of the auxiliary cutting tooth 1b2, so that when the drill bit body 1 is working, the main cutting tooth 1b1 is located in the front row for chip cutting and the auxiliary cutting tooth 1b2 is located in the back row for chip cutting. Conical cutting teeth and circular cutting teeth are provided on the gauge section 1a.

[0040] Various types of cutting teeth are provided on the main cutting teeth 1b1 and the auxiliary cutting teeth 1b2, and the various cutting teeth cooperate with each other to improve the cutting efficiency.

[0041] In this embodiment, the main cutting teeth 1b1 are composed of a plurality of circular cutting teeth, and the auxiliary cutting teeth 1b2 are composed of one or more limiting teeth and a plurality of pointed circular planar cutting teeth.

[0042] The limit teeth can reduce the stick-slip vibration of the drill bit caused by drastic changes in the penetration depth and rotation resistance during the drilling process; at the same time, it reduces the risk of tooth breakage caused by the rapid increase in the penetration depth of the main cutting tooth 1b1 into the rock formation, thereby increasing the overall service life of the drill bit.

[0043] The main cutting teeth and the auxiliary cutting teeth are provided with a height difference, and the height difference between the main cutting teeth and the auxiliary cutting teeth is equidistantly variable, and the height difference between the main cutting teeth and the auxiliary cutting teeth gradually decreases from the central axis of the drill body to the diameter protection direction.

[0044] The back chamfer of the pointed circular plane cutting teeth increases equidistantly from the central axis of the drill body to the diameter-preserving direction.

[0045] like Figure 5As shown in the figure, the circular cutting teeth can take advantage of high drilling speed when drilling in medium-soft homogeneous formations as the main teeth. When encountering thin interlayers of hard rock, the circular cutting teeth, as the main cutting teeth, first contact the formation. The height difference setting between the sharp circular plane teeth and the circular cutting teeth can control the penetration depth of the drill bit, balance the cutting depth variation of the drill bit in different formations, and maintain stability during drilling; at the same time, the sharp circular plane cutting teeth can further cut the rocks that have not been completely scraped by the main teeth, thereby assisting in rock breaking and protecting the main cutting teeth.

[0046] In one embodiment, the main blade and the auxiliary blade both adopt a 4°-12° spiral structure.

[0047] The spiral blades (main blades and auxiliary blades) can distribute the stress of the diameter section. By setting the number and angle of the blades, the underbalance force during the cutting process is close to 0, reducing the vibration of the drill bit and improving the overall stability of the drill bit. Both the main blade and auxiliary blade can adopt a 4°-10° spiral structure.

[0048] In one embodiment, an inclined section 1c is provided between the gauge section 1a and the neck 101 of the drill body 1, and a reverse scoring tooth is fixedly installed on the inclined surface of the inclined section. The reverse scoring tooth is a combination of a conical cutting tooth and a circular plane tooth.

[0049] Specifically, the inverted eye teeth are composed of two conical cutting teeth and two circular plane teeth, and the conical cutting teeth and the circular plane teeth are arranged alternately. The conical cutting teeth can crush the blocks that are too large, and the circular plane teeth can repair the well wall faster and more effectively.

[0050] In one embodiment, the pointed circular plane cutting tooth is cylindrical as a whole, and the side surface of the pointed circular plane cutting tooth has an inclined first plane g and a second plane h, and the first plane and the second plane are symmetrical with the axial section of the pointed circular plane cutting tooth, and the angle β between the intersecting ridges of the first plane and the second plane and the top surface of the pointed circular plane cutting tooth is 90°-120°.

[0051] The PDC drill bit has a very strong impact on the rock, so it is very easy to get stuck in the rock, so it is very easy to get stuck in the rock. In fact, PDC drill bits have the problem of biting down on the rock, but they are not easy to get stuck in the rock. Therefore, the drill bit should be used frequently, and it is recommended to use a PDC drill bit with a PDC bit as the core.

[0052] The auxiliary cutting teeth adopt an arbitrarily increasing back chamfer, especially when passing through heterogeneous formations. The large back chamfer has stronger impact resistance in hard formations and can balance the penetration depth and cutting speed of the drill bit in the interlayer.

[0053] In one embodiment, a water hole 103 is disposed on the crown of the drill bit body and between the cutting blades.

[0054] In one embodiment, at least three sharp circular planar cutting teeth are arranged in the auxiliary cutting teeth to ensure that the drilling operation can be carried out normally when the auxiliary cutting teeth are in active cutting action.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high stability PDC drill bit suitable for soft and hard interlaced formations, comprising: A drill body, wherein the bottom end of the drill body has a drill body crown, and the top of the drill body is fixedly connected with a drill thread, characterized in that: the drill body crown is provided with five cutting blades along the circumferential surface; The five cutting blades include three main blades and two auxiliary blades, and are distributed in the manner of main blade, auxiliary blade, main blade, auxiliary blade, and main blade, and are distributed in the directions of 0°, 70°, 140°, 225°, and 279°; The cutting blade has a gauge section and a cutting blade section. The cutting blade section is close to the head end of the crown of the drill body. The cutting blade section is provided with a main cutting tooth and an auxiliary cutting tooth along the rotation direction of the drill body when the drill body is working. The main cutting tooth is located in front of the auxiliary cutting tooth along the rotation direction of the drill body when the drill body is working. The gauge section is provided with a conical cutting tooth and a circular cutting tooth. The main cutting teeth are composed of a plurality of circular cutting teeth; The auxiliary cutting teeth are composed of one or more limiting teeth and a plurality of sharp circular plane cutting teeth; The sharp circular plane cutting tooth is cylindrical in shape as a whole, and the side surface of the sharp circular plane cutting tooth has an inclined first plane and a second plane, and the first plane and the second plane are symmetrical with the axial section of the sharp circular plane cutting tooth, and the angle β between the first plane and the second plane and the intersection ridgeline of the top surface of the sharp circular plane cutting tooth is 90°-120°; The main cutting teeth and the auxiliary cutting teeth are provided with a height difference, and the height difference between the main cutting teeth and the auxiliary cutting teeth is equidistantly variable, and the height difference between the main cutting teeth and the auxiliary cutting teeth gradually decreases from the central axis of the drill body to the diameter protection direction; The rear chamfer of the pointed circular plane cutting teeth increases equidistantly from the central axis of the drill body to the diameter-preserving direction.

2. A high stability PDC drill bit suitable for soft and hard interlaced formations according to claim 1, characterized in that: The main blade and the auxiliary blade both adopt a 4°-12° spiral structure.

3. A high stability PDC drill bit suitable for soft and hard interlaced formations according to claim 2, characterized in that: The main blade and the auxiliary blade both adopt a 4°-10° spiral structure.

4. A high stability PDC drill bit suitable for soft and hard interlaced formations according to claim 1, characterized in that: An inclined section is arranged between the gauge-guarding section and the neck of the drill bit body, and an inverted eye tooth is fixedly mounted on the inclined surface of the inclined section.

5. A high stability PDC drill bit suitable for soft and hard interlaced formations according to claim 4, characterized in that: The inverted eye teeth are a combination of conical cutting teeth and circular flat teeth.

6. A high stability PDC drill bit suitable for soft and hard interlaced formations according to claim 4, characterized in that: The inverted eye teeth are composed of two conical cutting teeth and two circular plane teeth, and the conical cutting teeth and the circular plane teeth are arranged alternately.

7. The high stability PDC drill bit suitable for soft and hard interlaced formations according to claim 1, characterized in that: A water hole is arranged on the crown of the drill bit body and between the cutting blades.

8. The high stability PDC drill bit suitable for soft and hard interlaced formations according to claim 1, characterized in that: At least three pointed circular plane cutting teeth are arranged among the auxiliary cutting teeth.

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