Rapid drilling and coring drill bit suitable for deep shale stratum

Abstract

The utility model discloses a quick drilling coring drill bit suitable for a deep shale stratum, which comprises a drill bit body, a crown-shaped head part arranged at the lower end of the drill bit body, and a through core inlet hole arranged along the axis of the crown-shaped head part, and is characterized in that four cutting blades are uniformly distributed on the crown-shaped head part; sharp round teeth, axe-shaped teeth and prism teeth are brazed on the cutting surface of each cutting blade; the upper part of each cutting blade extends towards the peripheral wall of the crown-shaped head part, and five gauge protection plane cutting teeth are arranged on the outer wall of each cutting blade; a chip groove is formed between every two adjacent cutting blades, two drill bit water holes are formed in each chip groove, inner gauge teeth are arranged in each chip groove, and the inner edge of each inner gauge tooth is tangent to the inner wall of the center inlet hole. An upper end inlet of each drill bit water hole is located on the arc-shaped slope of the inner step of the coronal head, and the arc-shaped slope is located below the female thread of the coronal head. The service life of the coring drill bit can be prolonged, and the deep stratum coring efficiency is effectively improved.

Description

Technical Field

[0001] The utility model relates to a drilling tool in the field of oil and gas, in particular to a rapid coring bit suitable for deep shale formations, belonging to the technical field of oil drilling tools. Background Art

[0002] Core is the original data used to analyze and study the physical properties, chemical composition and other characteristics of the formation during oil exploration and development. Only through a large number of analyses and studies of the core can a reasonable development plan be formulated for the oilfield, the oilfield reserves be accurately calculated, and production increase measures be formulated. Drilling coring is the most direct way to obtain core and plays an extremely important role in oil and gas exploration and development.

[0003] In order to explore reserves as soon as possible, more and more deep wells need to be cored, and the continuous coring section is getting longer and longer. The deep shale in the northern Jiangsu Basin is mainly deep - semi - deep lacustrine sediment, with high formation density and poor drillability. The coring rate of the shale formation is low, the single - run footage is small, and it is easy to block the core and wear the core, which greatly increases the coring trips and coring cycle, increases the drilling cost of deep - well construction, and also affects the efficient development of deep - layer oil and gas in the oilfield.

[0004] The existing problems are analyzed as follows: 1. When coring in the shale formation, in order to ensure the stability of the coring bit, an eight - blade or more - blade coring bit is generally used. The contact area between the blade and the bottom of the well is large. According to the working principle of the PDC bit and CFD hydraulics analysis, the more blades there are, the weaker the shear, crushing and plowing abilities are, the slower the rock - breaking speed is, and the lower the coring rate is; the higher the probability of repeated grinding of the broken core at the bottom of the well is, which increases the coring cycle and cost, and is also easy to cause core blockage and affect the coring recovery rate.

[0005] 2. The inner water eyes and core catcher seats in the inner cavity of the conventional coring bit are generally designed in a multi - platform step manner. During the coring process, the drilling fluid scours at a fixed point for a long time, and laminar flow is generated at the upper part of the step, which is easy to cause erosion of the water eyes and the inner cavity of the bit body, weaken the strength of the bit body, shorten the service life of the bit, and increase the number of trips. At the same time, the erosion of the broken formation core makes the core more fragmented and unable to enter the inner core barrel, affecting the coring footage. Summary of the Utility Model

[0006] The purpose of this part is to outline some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and the name of the utility model of this application, to avoid obscuring the purpose of this part, the abstract and the name of the utility model, and such simplifications or omissions cannot be used to limit the scope of the utility model.

[0007] In view of the above - mentioned and / or existing problems, the present utility model is proposed.

[0008] The purpose of the present utility model is to overcome the problems existing in the prior art, such as the low mechanical drilling rate caused by multi-wing coring bits, the easy erosion damage of the conventional drill bit body, and the short service life of the drill bit. A rapid coring drill bit applicable to deep shale formations is provided, which can extend the service life of the drill bit and effectively improve the coring efficiency of deep formations.

[0009] To solve the above technical problems, a rapid coring drill bit applicable to deep shale formations of the present utility model includes a drill bit body. A coronal head is provided at the lower end of the drill bit body, and a through coring hole is provided along the axis of the coronal head. Four cutting wings are evenly distributed on the coronal head. Tip-round teeth, axe-shaped teeth, and prism teeth are respectively brazed on the cutting surfaces of each cutting wing. The upper parts of each cutting wing extend towards the outer peripheral wall of the coronal head, and five gauge plane cutting teeth are respectively provided on the outer walls. Chip grooves are respectively provided between adjacent cutting wings. Two drill bit nozzles are respectively provided in each chip groove and internal gauge teeth are respectively provided. The inner edges of each internal gauge tooth are tangent to the inner wall of the coring hole.

[0010] Further, the included angle between the axis of each drill bit nozzle and the axis of the drill bit body is 5° - 8°.

[0011] Further, the aperture of each drill bit nozzle is 12 mm.

[0012] Further, the diameters of the tip-round teeth, axe-shaped teeth, and prism teeth are 16 mm.

[0013] Further, the internal gauge teeth are axe-shaped teeth and the exposed height is 1 - 2 mm.

[0014] Further, the five gauge plane cutting teeth are arranged in a three-plus-two pattern, and the exposed height is 2 - 3 mm.

[0015] Further, the tip-round teeth, axe-shaped teeth, and prism teeth on each cutting wing are arranged along a spiral line.

[0016] Further, the prism teeth are four-sided prisms, and two cutting inclined planes with an included angle of 165° are provided at the top.

[0017] Further, the upper end inlets of each drill bit nozzle are located on the arc-shaped slope of the inner step of the coronal head, and the arc-shaped slope is located below the female thread of the coronal head.

[0018] Further, two prism teeth are respectively provided on the cutting surfaces of the corresponding cutting wings.

[0019] Further, ordinary round teeth are also provided on the outermost or innermost sides of the cutting surfaces of each cutting wing.

[0020] Compared with the prior art, the utility model has achieved the following beneficial effects: The cutter wings, tooth arrangement, water holes, inner cavity design, etc. of the conventional coring bit are optimized and improved. It has the advantages of fast rock-breaking speed, high bit body strength, long service life, etc., and solves the defects such as low mechanical drilling speed of the multi-cutter-wing coring bit and easy erosion damage of the bit body during the coring process. Compared with the conventional coring bit, it has the advantages of fast rock-breaking speed, high bit body strength and long service life, effectively improving the coring speed and single-trip coring footage in deep shale formations. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. The drawings are only for reference and explanation, and are not used to limit the present utility model. Among them:

[0022] Figure 1 is the front view of the fast coring bit applicable to deep shale formations of the present utility model;

[0023] Figure 2 is Figure 1 the bottom view of;

[0024] Figure 3 is the top view of the coronal head;

[0025] Figure 4 is the three-dimensional view of the fast coring bit applicable to deep shale formations of the present utility model;

[0026] Figure 5 is the cross-sectional view of the fast coring bit applicable to deep shale formations of the present utility model;

[0027] Figure 6 is the front view of the pointed-round tooth in the present utility model;

[0028] Figure 7 is the three-dimensional view of the axe-shaped tooth in the present utility model;

[0029] Figure 8 is the three-dimensional view of the prism tooth in the present utility model;

[0030] In the figure: 1. Bit body; 1a. Weld seam; 2. Coronal head; 2a. Core inlet hole; 2b. Female thread of the coronal head; 2c. Arc-shaped slope; 3. Cutting cutter wing; 4. Bit water hole; 5. Pointed-round tooth; 6. Axe-shaped tooth; 7. Prism tooth; 8. Gauge plane cutting tooth; 9. Inner gauge tooth. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In the following description of the present utility model, the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating that the device must have a specific orientation.

[0032] In order to make the technical means, creative features, achieved purposes and effects realized by the present utility model easy to understand, the present utility model will be further described below with reference to specific drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs. The terms used in the description of the present utility model in this specification are only for the purpose of describing specific embodiments, and are not intended to limit the present utility model.

[0034] As Figures 1 to 8 shown, the present utility model optimizes and improves the conventional coring bit blade design, tooth arrangement, water eye, inner cavity design, etc., and has the advantages of fast rock breaking speed, high bit body strength, long service life, etc., effectively improving the coring speed and single trip coring footage in deep shale formations. Through processing technologies such as batching, pressing and forming, sintering, cooling and demolding, processing water eyes and threads, pretreatment, welding composite chips and precision grinding, a rapid coring bit applicable to deep shale formations is made into a steel body bit.

[0035] This coring bit mainly consists of three parts: a bit body 1, a crown head 2, and cutting blades 3. The crown head 2 is connected to the lower end of the bit body 1. A through core hole 2a is provided along the axis of the crown head 2 to accommodate the drilled core. A male thread is provided at the lower end of the bit body 1, and a groove is provided at the root of the male thread; a female thread is provided at the upper end of the crown head 2, and a groove is also provided on the outer periphery of the upper end. After the male thread at the lower end of the bit body 1 is screwed into the female thread 2b of the crown head, the upper and lower grooves on the outer periphery form a V shape, and a weld seam 1a is formed by welding the entire circumference, forming a double connection method of threading plus welding.

[0036] The cutting blades 3 are similar to conventional PDC bits, with a total of four blades. Each cutting surface of each cutting blade 3 is brazed with pointed round teeth 5, ax-shaped teeth 6, and prism teeth 7 for cutting the formation and improving the drilling speed.

[0037] Two drill bit nozzles 4 are installed in the middle of the chip discharge groove between every two cutting wings 3, which are inclined downward at an angle of 5°-8° and used to wash the bottom of the well, cool, clean and lubricate the cutting teeth, and effectively prevent the cutting wings 3 from being mud-packed. Five gauge protection flat cutting teeth 8 are arranged on the outer wall of the upper part of each cutting wing 3 extending towards the outer peripheral wall of the crown head 2. The five gauge protection flat cutting teeth 8 are arranged in two rows, with three teeth arranged close to the cutting surface and two teeth arranged at the back. This improves the working stability and wear resistance of the drill bit body, and at the same time has the function of reverse reaming when pulling out the drill bit.

[0038] There are internal gauge protection teeth 9 between two cutting wings 3 respectively. Each internal gauge protection tooth 9 can be an axe-shaped tooth, and its inner edge is tangent to the inner wall of the centering hole 2a to ensure the formation and size of the core during the coring process and improve the coring speed. An axe-shaped tooth is arranged between the wings as the internal gauge protection tooth 9.

[0039] To improve the rock-breaking speed, the coring bit is designed with four cutting wings to improve the rock-breaking efficiency. There are eight drill bit nozzles 4 inclined downward at an angle of 5°-8°. The diameter of the drill bit nozzles 4 is 12 mm. The two nozzles arranged between adjacent wings can effectively prevent the drill bit from being mud-packed. Each wing is designed with a single row of teeth, and the 16 mm prism teeth 7, axe-shaped teeth 6 and pointed-round teeth 5 are arranged alternately to form a composite cutting structure; five gauge protection flat cutting teeth 8 are arranged on the side of the cutting wing 3 to improve the stability of the drill bit body.

[0040] The pointed-round teeth 5, axe-shaped teeth 6 and prism teeth 7 on each cutting wing 3 can be arranged along a spiral line to further improve the cutting effect. Ordinary round teeth can also be provided on the outermost or innermost side of the cutting surface of each cutting wing 3 to protect the main cutting teeth.

[0041] The inner cavity nozzle of the crown head and the step of the core catcher seat are designed as an arc-shaped slope 2c to reduce the influence of drilling fluid erosion and extend the service life of the drill bit.

[0042] The crown body of the steel body drill bit has high strength, strong erosion resistance, high brazing strength of PDC composite inserts, is easy to be repaired for the second time, and has relatively low production cost. Compared with the straight wings of the conventional coring bit, the four-wing design adopts a short parabolic crown profile design, which improves the stability and impact resistance of the drill bit and enhances the lateral cutting ability. The gentle crown structure can make all the cutting teeth on the drill bit evenly stressed. When drilling in harder formations, the crown top part of the drill bit can concentrate more drilling pressure, making the cutting teeth produce a greater shearing effect and more effectively shearing the rock. The design of each wing is optimized from the conventional one nozzle to two nozzles, effectively reducing the probability of the drill bit being mud-packed. Eight 12 mm nozzles are arranged. The non-vertical jet direction of the nozzles is designed to be inclined downward at an angle of 5°-8°, so that the drilling fluid forms a vortex at the bottom of the well, accelerating the upward return speed of the cuttings, reducing the erosion effect on the core, improving the upward return ability of the cuttings, and increasing the coring recovery rate of the broken formation.

[0043] The side of the cutter wing is improved from the conventional arrangement of cemented carbide bars to the arrangement of five gauge plane cutting teeth 8. The exposed height of the gauge plane cutting teeth 8 is 2-3 mm, which improves the working stability and wear resistance of the bit body, and at the same time has the function of tripping and reaming. One axe-shaped tooth with an exposed height of 1-2 mm is arranged between the two cutter wings as the internal gauge tooth 9, which ensures the formation and size of the core during the coring process, and at the same time ensures the cutting smoothness during the core cutting process and improves the core cutting speed.

[0044] Each cutter wing is designed with a single row of teeth to improve the cutting ability of the cutter wing. In order to facilitate chip removal and cleaning of the cutting teeth, a spiral tooth arrangement is designed. The diameter of the cutting teeth is 16 mm, which is suitable for medium-soft to medium-hard formations. The conventional axe-shaped tooth is improved. The cylindrical surface of the axe-shaped tooth is improved to a four-sided prism, and two cutting inclined surfaces with an included angle of 165° are provided at the top. This tooth is named the prism tooth 7, which is sharper than the axe-shaped tooth and has a faster rock-breaking speed. Each cutter wing adopts a low-density tooth arrangement design, and the tooth pitch is 3-5.5 mm. The tooth arrangement adopts a composite cutting structure formed by the prism tooth 7, the axe-shaped tooth 6, and the pointed-round tooth 5, which is beneficial to rapid drilling in deep formations. A certain spacing is left between each cutting tooth, and the spacing is smaller closer to the outside of the cutter wing. The cutting angle of the pointed-round tooth 5 is designed to be 10°-15°, the cutting angle of the prism tooth 7 is designed to be 15°-18°, and the cutting angle of the axe-shaped tooth 6 is designed to be 18°-20°. The exposed height of each tooth bottom is designed to be 5-7 mm, which is beneficial to cutting into the formation. The internal and external exposed heights are both designed to be 2-3 mm, making the wear of the bit more uniform, ensuring the rock-breaking efficiency and wear amount of the cutting teeth, and reducing the possibility of tooth chipping and bit damage. The pointed-round tooth 5 contacts the formation first for shearing, then the axe-shaped tooth 6 contacts the formation to complete plowing, and finally the prism tooth 7 contacts the formation to complete crushing.

[0045] An arc-shaped slope 2c is provided on the lower step of the coronal head female thread 2b. The upper entrances of each bit water eye 4 are located on this arc-shaped slope 2c, which reduces the erosion of the drilling fluid flow on the inner cavity step of the bit body. On the premise of ensuring the smooth placement of the core catcher, the arc-shaped slope 2c can reduce the damage of the bit body caused by the long-term erosion of the drilling fluid, ensure the strength of the bit body, extend the service life of the coring bit, improve the deep well coring efficiency, and shorten the working time of the coring bit.

[0046] During coring operation, the coring tool assembly used is: Φ215mm coring bit + Φ178mm coring barrel + Φ165mm spiral drill collar * 9 + Φ127mm heavy drill pipe * 7 + Φ165mm downhole shock absorber + Φ127mm heavy drill pipe * 14 + Φ127mm drill pipe. After running the drill string to the bottom, check the well depth and start core building. The recommended core building parameters are: WOB 10 - 20KN, rotary speed 40r / min, pump rate 15 - 20L / s. After core building for 0.3m, start normal coring. The recommended normal coring drilling parameters are: WOB 40 - 80KN, rotary speed 60 - 80r / min, pump rate 20 - 25L / s. During drilling, without special circumstances, do not stop the pump, do not stop rotating, and the coring bit does not leave the bottom. Record the penetration rate every 0.5m of coring drilling, closely monitor the changes in penetration rate and formation lithology. In case of any abnormality, immediately cut the core and pull out the drill string.

[0047] The above is only the preferred and feasible embodiment of the present utility model, which shows and describes the basic principles, main features and advantages of the present utility model. It is not intended to limit the patent protection scope of the present utility model. Those skilled in the art should understand that the present utility model is not limited by the above embodiments. Except for the above embodiments, without departing from the spirit and scope of the present utility model, the present utility model may have other embodiments. The present utility model will also have various changes and improvements. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present utility model. The protection scope required by the present utility model is defined by the appended claims and their equivalents. The technical features not described in the present utility model can be realized by or adopted from the prior art, and will not be elaborated here.

Claims

1. A fast core drilling drill bit suitable for deep mudstone formations, comprising a drill bit body, a crown head is provided at the lower end of the drill bit body, and a through core hole is provided along the axis of the crown head, characterized in that: Four cutting blades are evenly distributed on the crown-shaped head, and the cutting surface of each cutting blade is brazed with sharp round teeth, axe-shaped teeth and prismatic teeth respectively. The upper part of each cutting blade extends toward the outer peripheral wall of the crown-shaped head and the outer wall is respectively provided with five diameter-maintaining plane cutting teeth; chip grooves are respectively provided between adjacent cutting blades, and two drill water holes are respectively provided in each chip groove and an inner diameter-maintaining tooth is respectively provided, and the inner edge of each inner diameter-maintaining tooth is tangent to the inner wall of the core entry hole.

2. The fast drilling and coring drill bit suitable for deep shale formations according to claim 1, characterized in that: The angle between the axis of each drill bit water hole and the axis of the drill bit body is 5°-8°.

3. The fast drilling and coring drill bit suitable for deep shale formations according to claim 1, characterized in that: The diameter of each drill bit water hole is 12mm.

4. The fast drilling and coring drill bit suitable for deep shale formations according to claim 1, characterized in that: The diameter of the pointed round teeth, axe-shaped teeth and prismatic teeth is 16 mm.

5. The fast drilling and coring drill bit suitable for deep shale formations according to claim 1, characterized in that: The inner diameter-keeping teeth are axe-shaped teeth and the exposed height is 1-2 mm.

6. The fast drilling and coring drill bit suitable for deep shale formations according to claim 1, characterized in that: The five gauge-protected flat cutting teeth are arranged in a three plus two arrangement, and the exposed height is 2-3mm.

7. The fast core drilling drill bit suitable for deep shale formations according to claim 1, characterized in that: The pointed round teeth, axe-shaped teeth and prismatic teeth on each cutting blade are arranged along a spiral line.

8. The fast drilling and coring drill bit suitable for deep shale formations according to claim 1, characterized in that: The prism teeth are four-sided prisms, and two cutting bevels with an angle of 165° are arranged on the top.

9. The fast drilling and coring drill bit suitable for deep shale formations according to claim 1, characterized in that: The upper end entrance of each drill bit water hole is located on the arc slope of the step inside the crown head, and the arc slope is located below the female thread of the crown head.

10. The fast drilling and coring drill bit suitable for deep shale formations according to any one of claims 1 to 9, characterized in that: The prismatic teeth are respectively provided with two on the cutting surface of the corresponding cutting blade.

11. A fast core drilling drill bit suitable for deep shale formations according to any one of claims 1 to 9, characterized in that: The outermost or innermost side of the cutting surface of each cutting blade is also provided with ordinary round teeth.

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