Small-dip-angle coring drilling tool capable of replacing drill bit without lifting drill

Abstract

The invention provides a small-dip-angle coring drilling tool capable of replacing a drill bit without lifting a drill, and relates to the technical field of geological prospecting, the small-dip-angle coring drilling tool comprises an inner pipe drilling tool and an outer pipe drilling tool, the inner pipe drilling tool comprises a main drill bit, a limiting stopper, a convergence claw, a drill bit frame, an auxiliary drill bit, an expanding and converging shaft, a suspension connector and a spearhead, and the outer pipe drilling tool comprises a positioning end pipe and an upper outer pipe. A plurality of arrow-shaped splines used for aiming the auxiliary drill bits are distributed on the drill bit frame and the positioning end pipe at intervals in the circumferential direction of the drill bit frame and the positioning end pipe, and when the inner pipe drilling tool enters the outer pipe drilling tool, the arrow-shaped splines can enable the auxiliary drill bits to directly face the rectangular window holes of the drill bit frame. The arrow-shaped spline is arranged in the positioning end pipe, sharp point suspension is optimized into conical surface suspension, the stress area of four points is increased, the suspension mechanism can bear impact and large pulling force, and burrs are avoided.

Description

Technical Field

[0001] This invention relates to the field of geological exploration technology, and more specifically, to a small-angle core drilling tool that allows for non-drill bit replacement without lifting the drill bit. Background Art

[0002] The drill bit-changing-without-drill-lift technology enables rapid drill bit replacement, meeting the need for quick drilling through complex formations. However, existing positioning-type non-drill bit-changing drill tools are only suitable for vertical boreholes. In complex geological conditions such as low-angle hard rock and fractured zones, drill bit wear is rapid, leading to significant borehole collapse or instability. The drill bit-changing-without-drill-lift technology avoids the difficult technical problem of accelerated borehole collapse or instability caused by frequent tripping in and out of the drill string, thus improving the success rate of drilling operations. Existing positioning-type non-drill bit-changing drill tools have a low convergence success rate in boreholes with small inclination angles. Drilling in low-angle formations has always faced numerous challenges in geological exploration. At inclination angles of 45°–60°, the probability of borehole collapse increases by 3–5 times. Furthermore, uneven drill bit wear and a 120% increase in drill bit joint wear rate severely affect drilling efficiency and core quality. Furthermore, in shallow-angle drilling, the inner tubing drill bit is in a near-horizontal position, and the auxiliary drill bit is close to the borehole wall, increasing the difficulty of opening it. During retrieval, the auxiliary drill bit converges, but due to the downward weight of the main drill bit, it is difficult for the auxiliary drill bit to converge synchronously, greatly reducing the success rate of retrieval. During the lifting of the inner tubing drill bit assembly, the gap between the inner tubing drill bit and the drill rod is small, creating a pressure difference during the retrieval process, resulting in high retrieval resistance and suction at the bottom of the borehole, severely affecting the stability of the borehole wall.

[0003] Chinese Patent Publication No. CN103603625A discloses a casing coring drill bit and a casing coring drilling method. It mainly consists of a deployable inner casing drill bit and an outer casing drill bit connected to the casing. The inner casing drill bit comprises a axially movable tension shaft assembly and a fixed drill bit frame assembly, with the tension shaft assembly housed within the drill bit frame assembly. The outer casing drill bit consists of an upper outer tube with a centralizing ring in its upper cavity and a sealing ring in its lower cavity, and a positioning end tube located below the upper outer tube. Its drawbacks include: the four sharp points of the arrowhead spline on the positioning end tube and the lower end face of the suspension joint are prone to burrs, leading to convergence and positioning failures; and the drill bit cannot be used for drilling at small inclination angles. Summary of the Invention

[0004] The purpose of this invention is to provide a small-angle core drilling tool that does not require drill bit lifting for changing. It has an arrow-shaped spline inside the positioning end tube, which optimizes the cusp suspension to a conical suspension, increases the force-bearing area at four points, and enables the suspension mechanism to withstand impact and large pulling force without burrs.

[0005] This invention is achieved through the following technical solution: a small-angle core drilling tool for changing drill bits without lifting the drill bit, comprising an inner tube drilling tool and an outer tube drilling tool. The inner tube drilling tool includes a main drill bit, a limiter, a convergence claw, a drill bit holder, an auxiliary drill bit, a tensioning shaft, a suspension joint, and a spearhead. The outer tube drilling tool includes a positioning end tube and an upper outer tube. Both the drill bit holder and the positioning end tube have multiple arrow-shaped splines spaced along their circumference for aiming at the auxiliary drill bit. When the inner tube drilling tool enters the outer tube drilling tool, the arrow-shaped splines enable the auxiliary drill bit to be directly aligned with the rectangular window of the drill bit holder.

[0006] Furthermore, four arrow-shaped splines are distributed circumferentially inside the positioning end tube, and the tips of at least two of the arrow-shaped splines are offset relative to the outer splines of the drill bit holder.

[0007] Furthermore, the tip of one of the arrow splines is offset by 2.5° from the position in the array distribution case, and the tip of another arrow spline is offset by 5° from the position in the array distribution case.

[0008] Furthermore, a strong magnetic column is embedded in the head of the auxiliary drill bit.

[0009] Furthermore, the lip surface of the auxiliary drill bit is provided with a tension guide groove.

[0010] Furthermore, the lip surface of the auxiliary drill bit is provided with a cooling water groove, which is connected to the end of the tension guide groove.

[0011] Furthermore, a pressure relief hole is provided on the spearhead.

[0012] Furthermore, the spearhead has four pressure relief holes distributed circumferentially.

[0013] Furthermore, the retracting claw is provided with cooling water holes.

[0014] Furthermore, the drill bit holder is provided with a sand removal hole.

[0015] The technical solution of the present invention has at least the following advantages and beneficial effects: 1. This invention optimizes the suspension of four cusp points into a conical suspension by adding four conical splines to the positioning end tube, thereby increasing the force-bearing area of ​​the four points. This allows the suspension mechanism to withstand impacts and larger lifting forces without burrs. At the same time, the positions of two of the conical splines are designed to be at an angle to the array distribution state, adopting an asymmetrical design to reduce the probability of aiming at dead points.

[0016] 2. This invention employs a combined mechanism of strong magnetic adsorption and hydraulic convergence. Under the dual action of the convergence claw and strong magnet, the convergence of the auxiliary drill bit is controlled throughout the entire retrieval process, thereby improving the retrieval success rate. Attached Figure Description

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal tube drilling tool of the present invention; Figure 3 This is a schematic diagram of the structure of the outer casing drill bit of the present invention; Figure 4 This is a schematic diagram of the positioning end tube of the present invention; Figure 5 This is a schematic diagram of the distribution structure of the arrow-shaped spline in the positioning end tube of the present invention; Figure 6 This is a three-dimensional structural diagram of the drill bit holder of the present invention; Figure 7 This is a schematic diagram of the auxiliary drill bit and drill bit holder of the present invention; Figure 8 This is a schematic diagram of the tension guide groove and cooling water groove of the present invention on the auxiliary drill bit; Figure 9 This is a schematic diagram of the pressure relief hole on the spearhead of the present invention; Reference numerals: 1-Main drill bit, 2-Limiter, 3-Converging claw, 31-Cooling water hole, 4-Drill bit holder, 41-Sand removal hole, 42-External spline, 43-Rectangular window hole, 5-Secondary drill bit, 51-Strong magnetic column, 52-Converging guide groove, 53-Cooling water tank, 6-Positioning end tube, 7-Converging shaft, 8-Suspension joint, 9-Spearhead, 91-Pressure relief hole, 10-Arrow-shaped spline, 101-Pit. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] Example The following is for reference Figures 1-9 As shown in the illustration, and further explained with reference to specific embodiments, this embodiment provides a small-angle core drilling tool for changing drill bits without lifting the drill bit. Figure 1 , Figure 2As shown, the inner casing drilling tool includes a main drill bit 1, a limiter 2, a convergence claw 3, a drill bit holder 4, an auxiliary drill bit 5, a tensioning shaft 7, a suspension joint 8, and a spearhead 9; (Refer to...) Figure 3 As shown, the outer casing drill string includes a positioning end pipe 6 and an upper outer casing 11.

[0021] Reference Figure 4 , Figure 6 As shown, the drill bit holder 4 has multiple arrow-shaped splines 10 spaced along its circumference for aiming at the auxiliary drill bit 5. When the inner tube drill bit enters the outer tube drill bit, the arrow-shaped splines 10 ensure that the auxiliary drill bit 5 is directly aligned with the rectangular window 43 of the drill bit holder 4. By adding conical arrow-shaped splines 10 to the positioning end tube 6, the suspension of the four cusps 101 is optimized to a conical suspension, increasing the force-bearing area at the four points. This allows the positioning end tube 6 to withstand impacts and larger pulling forces without burrs.

[0022] Reference Figure 4 , Figure 5 As shown, four arrow-shaped splines 10 are distributed circumferentially within the positioning end tube 6, relative to the four external splines 42 of the drill bit holder 4. The tips 101 of two of the arrow-shaped splines 10 are offset, with the tip 101 of one arrow-shaped spline 10 offset by 2.5° from its position in the array distribution, and the tip 101 of the other arrow-shaped spline 10 offset by 5° from its position in the array distribution. By arranging the multiple arrow-shaped splines 10 in an asymmetrical structure, an asymmetrical aiming structure design is formed with the drill bit holder 4 to reduce the probability of aiming dead points.

[0023] Reference Figure 1 , Figure 7 As shown, a strong magnetic column 51 is embedded in the head of the auxiliary drill bit 5. In boreholes with small inclination angles, the auxiliary drill bit 5 in the convergence assembly is in a near-horizontal or inclined position. At this time, under the dual action of the convergence claw 3 and the strong magnetic column 51, the convergence process of the auxiliary drill bit 5 is controlled throughout the retrieval process, improving the retrieval success rate. (Refer to...) Figure 7 , Figure 8 As shown, the lip surface of the auxiliary drill bit 5 is provided with a tension guide groove 52 and a cooling water groove 53, and the cooling water groove 53 is connected to the end of the tension guide groove 52. By designing a water groove with a width of 6 mm at the middle position of the lip surface of the auxiliary drill bit 5, the cooling effect of the auxiliary drill bit 5 is improved, and the rock breaking efficiency of the auxiliary drill bit 5 is increased.

[0024] Reference Figure 7As shown, the bottom of the convergent claw 3 is symmetrically designed with four Φ4 cooling water holes 31. During drilling, due to the complex formation, rock powder may not be removed in time, and some rock powder may enter the cavity of the convergent claw 3, causing convergence to be obstructed and resulting in failure to retrieve the inner tube drill bit. The cooling water holes 31 provide high-pressure drilling fluid during drilling, which not only flushes the cavity of the convergent assembly but also further cools the auxiliary drill bit 5. The drill bit frame 4 is also equipped with desanding holes 41, which use centrifugal force to remove sand during drilling, further ensuring the reliability of convergence.

[0025] Reference Figure 1 , Figure 9 As shown, the spearhead 9 has four pressure relief holes 91 arranged circumferentially. During the lifting of the inner tubing drill string, the pressure relief holes 91 are open due to gravity. The drilling fluid flows through the hydraulic holes and the guide rod to the bottom of the hole, reducing the pressure of the fluid column on the upper part of the inner tubing drill string, increasing the retrieval speed, and also reducing the suction effect on the bottom of the hole. Generally, there is drilling fluid inside the drill pipe in the hole. When retrieving the inner tubing drill string, the gap between the outer diameter of the inner tubing drill string and the inner diameter of the drill pipe is very small, with a diameter difference of mostly 1-2 mm. During drilling in complex formations, the use of drilling fluid causes mud to form on the inner wall of the drill pipe. The drilling fluid inside the drill pipe needs to be continuously depressurized downwards through this gap so that the inner tubing drill string can continue to move upwards. This is a piston motion. Therefore, the descent speed of the inner tubing drill string is relatively slow, the surface winch is under heavy load, and sometimes the retrieval wire rope may even break, causing the drill string to be pulled up too high, which seriously affects the retrieval efficiency. By designing a pressure relief hole 91 on the spearhead 9, the water flow area can be increased by about 60%, while reducing the damage to the hole wall caused by suction at the bottom of the hole.

[0026] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A small-angle core drilling tool for non-drill bit changing, comprising an inner tube drilling tool and an outer tube drilling tool, wherein the inner tube drilling tool includes a main drill bit (1), a limiter (2), a convergence claw (3), a drill bit holder (4), a secondary drill bit (5), a tensioning shaft (7), a suspension joint (8), and a spearhead (9); and the outer tube drilling tool includes a positioning end tube (6) and an upper outer tube (11), characterized in that, The positioning end tube (6) has multiple arrow-shaped splines (10) spaced apart along its circumference for aiming at the auxiliary drill bit (5). When the inner tube drill bit enters the outer tube drill bit, the arrow-shaped splines (10) and the outer spline (42) of the drill bit holder (4) form an aiming point, which enables the auxiliary drill bit (5) to be directly facing the rectangular window (43) of the drill bit holder (4).

2. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 1, characterized in that, The positioning end tube (6) has four arrow-shaped splines (10) distributed circumferentially relative to the outer spline (42) of the drill bit holder (4), wherein the tips (101) of at least two of the arrow-shaped splines (10) are offset.

3. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 2, characterized in that, The tip (101) of one of the arrow splines (10) is offset by 2.5° from the position in the array distribution case, and the tip (101) of one of the arrow splines (10) is offset by 5° from the position in the array distribution case.

4. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 1, characterized in that, The head of the auxiliary drill bit (5) is fitted with a strong magnetic column (51).

5. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 1, characterized in that, The lip surface of the auxiliary drill bit (5) is provided with a tension guide groove (52).

6. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 1, characterized in that, The lip surface of the auxiliary drill bit (5) is also provided with a cooling water tank (53), which is connected to the end of the tension guide groove (52).

7. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 1, characterized in that, The spearhead (9) is provided with a pressure relief hole (91).

8. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 7, characterized in that, The spearhead (9) has four pressure relief holes (91) distributed circumferentially.

9. The small-angle core drilling tool for changing drill bits without lifting the drill bit according to claim 1, characterized in that, The converging claw (3) is provided with cooling water holes (31).

10. The small-angle core drilling tool for changing drill bits without lifting the drill bit, as described in claim 1 or 9, is characterized in that... The drill bit holder (4) is provided with a sand removal hole (41).

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