Lightweight drilling rod for complex stratum drilling and drilling method

Abstract

The invention discloses a complex stratum drilling lightweight drill rod and a drilling method, the drill rod comprises a drill rod body, the cross section of the drill rod body is in an equidistant ring shape, the equidistant ring shape is composed of arcs and straight lines, and both ends of the drill rod body are provided with screwed joints. Through structural innovation, the drill rod structure with high torsion resistance is designed, and on the premise of ensuring the strength of the drill rod, the cross sectional area of the drill rod is reduced, so that the dead weight of the drill rod is reduced, and a lightweight drilling technical system is formed; the phenomena that the drilling resistance is large, the drilled hole is prone to collapsing and the drilling track is seriously deflected due to the fact that the self weight of the drill rod is large are effectively relieved, meanwhile, the labor intensity of operators is relieved, and safe and efficient drilling of complex stratums can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling engineering, and in particular relates to a lightweight drill rod and a drilling method for drilling in complex strata. Background Art

[0002] Drilling construction in complex drilling environments such as soft and protruding coal seams, soft and hard composite formations, tuberculosis formations, and superhard formations is a recognized technical problem. Due to the low strength, soft and broken coal and rock mass in complex geological conditions, the heavy weight of the drill rod during drilling leads to large deformation of the borehole wall, local instability and damage, and serious deviation of the drilling trajectory, making drilling construction difficult. Steel drill rods, aluminum alloy drill rods, and composite drill rods have been used in domestic and foreign mine tests. Aluminum alloy drill rods have the disadvantages of low hardness, easy wear, easy to produce scratches, wear marks, and breakage during use, and unreliable connection with steel joints; while composite materials have diverse structures and different hardnesses, and the price of composite drill rods is about 3 times that of ordinary drill rods, which increases the cost. In comprehensive comparison, steel drill rods are still the most effective and economical drilling tools, but the current steel drill rods have a heavy weight, resulting in large friction resistance. During drilling, drill jams and drill breaks occur frequently, resulting in shallow drilling depth and low drilling efficiency. Therefore, conventional steel drill rods, aluminum alloy drill rods and composite drill rods are not suitable for soft coal rock areas with complex geological conditions. It is urgent to develop a new type of drilling tool that is lightweight and high-strength, thereby reducing the labor intensity of the workers, while effectively reducing the rotational resistance of the drill rod and indirectly reducing the power loss of the drilling rig. Summary of the invention

[0003] In order to solve the deficiencies in the prior art and in combination with the problems existing in the use of existing conventional drilling tools, the present invention provides a lightweight drill rod and drilling method for drilling in complex formations with light weight, good hole protection effect, high slag removal efficiency, and conducive to improving drilling depth and efficiency.

[0004] In order to solve the above technical problems, the present invention adopts the following technical scheme: a lightweight drill rod for drilling in complex formations, comprising a drill rod body with a hollow structure, a female threaded joint and a male threaded joint are respectively provided at both ends of the drill rod body, the cross-sectional shape of the drill rod body is a square ring with four edges and corners all transitioned into arcs, and a surface of the drill rod body is axially provided with a plurality of spiral grooves or spiral ridges arranged in a circular array, and the spiral directions of the spiral grooves or spiral ridges are the same.

[0005] The distance between the outer side surfaces and the distance between the inner side surfaces of the two opposite sides of the square ring are respectively the outer side length H and the inner side length h, and H is 1.2 to 3.2 times of h.

[0006] The square annular shape includes four straight line segments and four arc segments that are alternately and closed-loop connected. The wall thickness b1 of the straight line segments is less than or equal to the wall thickness b2 of the arc segments, and the value range of the straight line wall thickness b1 is 5mm ≤ b1 ≤ 10mm.

[0007] The drilling method of the lightweight drill pipe for complex formation drilling, which uses the described drill pipe for operation, includes the following steps: (1). Determine different drill pipes according to the firmness coefficient f of the formation at the construction site; (2). Determine the rotary speed and drilling speed of the drill rig according to the firmness coefficient f of the formation at the construction site; (3). Arrange the drill rig, install the drill pipe, set up a dust removal device or a gas-water-sludge separation device at the hole opening, connect the drill pipe to an air pipe or a water pipe, start the drill rig to drill, stop drilling after reaching the designed depth, and withdraw the drill pipe; (4). Move the drill rig to drill another hole; (5). Repeat steps (2) and (3).

[0008] The specific method for determining different drill pipe structures in step (1) is as follows: When the formation firmness coefficient 0 < f ≤ 0.3, a spiral groove or spiral rib structure is set on the surface of the drill pipe body, and the depth of the spiral groove or the height of the spiral rib on the surface of the drill pipe body is set to 2mm - 3.5mm; When the formation firmness coefficient 0.3 < f ≤ 0.8, a spiral groove or spiral rib structure is set on the surface of the drill pipe body, and the depth of the spiral groove or the height of the spiral rib set on the surface of the drill pipe body is 0.5mm - 2mm; When the formation firmness coefficient f > 0.8, use the hydraulic slag discharge method for drilling, and no spiral groove or spiral rib structure is set on the surface of the drill pipe body.

[0009] The specific method for determining the rotary speed and drilling speed of the drill rig in step (2) is as follows: When the formation firmness coefficient 0 < f ≤ 0.3, the rotary speed of the drill rig is designed to be 200 r / min - 360 r / min, and the drilling speed is designed to be 0.2 m / min - 0.6 m / min; When the formation firmness coefficient 0.3 < f ≤ 0.8, the rotary speed of the drill rig is designed to be 150 r / min - 200 r / min, and the drilling speed is designed to be 0.4 m / min - 0.8 m / min; When the formation firmness coefficient f > 0.8, the rotary speed of the drill rig is designed to be 150 r / min - 200 r / min, and the drilling speed is designed to be 0.6 m / min - 1 m / min.

[0010] By adopting the above technical scheme, the present invention has outstanding substantial features and significant progress compared with the prior art. Here is an example. For example, the most commonly used Φ73 mm circular groove drill rod has slight differences in drill rods produced by different manufacturers. The wall thickness of the drill rod body is 14-16 mm, and the weight of the drill rod is 19-23 kg / m. Calculated at an average of 21 kg, when constructing a 150m drilling hole, the weight of the drill rod in the borehole reaches 3.15t. In the design and operation of drilling equipment, an overweight drill rod will not only put pressure on the mechanical structure of the drilling rig and increase the risk of failure, but may also cause the drill rod to tilt during drilling due to the high center of gravity, affecting the construction accuracy; in addition, bearing weight and pressure for a long time may cause fatigue of the drill rod material, especially causing cracks and other damage under high frequency use, and under complex geological conditions, the friction and impact of the drill rod may also cause the surrounding coal body to move, thereby causing the hole wall to collapse, endangering construction safety.

[0011] The formula for the resistance moment of the circular groove drill pipe section is: From the outer diameter d of 73mm and the inner diameter d1 of 43mm, we can get: Wy=33593.85mm 3 ;Gy=21.02kg.

[0012] The present invention designs a quadrilateral structure based on the principle of cross-sectional resistance moment of structural mechanics. The cross-sectional resistance moment formula of the lightweight drill pipe of the present invention is: From the outer side length H of 65mm and the inner side length h of 46.5mm, we can get: Ws=33782.82mm 3 ;b1=9.25mm;Gs=14.6kg.

[0013] It can be seen that the lightweight drill rod of the present invention is 30.54% lighter than the circular groove drill rod. Therefore, when the square ring structure is subjected to torque, the arc structure of the corners of the square ring structure can disperse stress more effectively, reduce the occurrence of concentrated stress points, and thus reduce the risk of material damage; in addition, the square ring structure not only provides better torsion resistance, but also improves stability when it is subjected to bending loads at the same time, so that it can better withstand external shocks and torque in complex construction environments, and its geometric shape makes the torsion resistance more uniform, thereby reducing the risk of instability caused by torsion. Therefore, the present invention forms a lightweight drilling technology system, which effectively alleviates the large drilling resistance, easy hole collapse and serious drilling trajectory deviation caused by the heavy weight of the drill rod, and at the same time reduces the labor intensity of operators, which is conducive to achieving safe and efficient drilling in complex formations. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the appearance structure of a lightweight drill rod according to a first embodiment of the present invention; Figure 2 is an axial cross-sectional view of a first embodiment of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of a lightweight drill pipe according to a first embodiment of the present invention; Figure 4 This is a schematic diagram of the appearance structure of a lightweight drill rod according to a second embodiment of the present invention; Figure 5 It is a schematic diagram of the cross-sectional structure of a lightweight drill rod according to Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0015] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0016] Embodiment 1 like Figure 1-3 As shown, a lightweight drill rod for drilling in complex formations comprises a drill rod body 1 with a hollow structure, a female threaded joint 2 and a male threaded joint 4 are respectively provided at both ends of the drill rod body 1, the cross-sectional shape of the drill rod body 1 is a square ring with four edges and corners all transitioned into arcs, and a surface of the drill rod body 1 is axially provided with a plurality of spiral grooves or spiral ridges 3 arranged in a circumferential array, and the spiral directions of the spiral grooves or spiral ridges 3 are the same.

[0017] The distance between the outer side surfaces and the distance between the inner side surfaces of the two opposite sides of the square ring are respectively the outer side length H and the inner side length h, and H is 1.2 to 3.2 times of h.

[0018] The square ring includes four straight line segments and four arc segments that are alternately and closed-loop connected. The wall thickness b1 of the straight line segment is less than or equal to the wall thickness b2 of the arc segment. The value range of the straight line wall thickness b1 is 5mm≤b1≤10mm.

[0019] A drilling method for a lightweight drill rod for drilling in complex formations, using the drill rod for operation, comprises the following steps: (1) Determine the use of different drill rods based on the solidity coefficient f of the stratum at the construction site; (2) Determine the drilling rig rotation speed and drilling speed based on the solidity coefficient f of the stratum at the construction site; (3) Arrange the drilling rig, install the drill rod, set up a dust removal device or a gas-water-slag separation device at the hole mouth, connect the drill rod to the air duct or water pipe, start the drilling rig to drill, stop drilling after drilling to the designed depth, and withdraw the drill rod; (4) Move the drilling rig to drill another borehole; (5) Repeat steps (2) and (3).

[0020] Step (1) The specific method of determining the use of different drill pipe structures is: When the formation firmness coefficient \(0 < f\leqslant0.3\), a spiral groove or a spiral rib \(3\) structure is arranged on the surface of the drill pipe body \(1\), and the depth of the spiral groove or the height of the spiral rib on the surface of the drill pipe body \(1\) is set to be \(2\mathrm{mm}-3.5\mathrm{mm}\); When the formation firmness coefficient \(0.3 < f\leqslant0.8\), a spiral groove or a spiral rib \(3\) structure is arranged on the surface of the drill pipe body \(1\), and the depth of the spiral groove or the height of the spiral rib arranged on the surface of the drill pipe body \(1\) is set to be \(0.5\mathrm{mm}-2\mathrm{mm}\); When the formation firmness coefficient \(f > 0.8\), drilling is carried out by means of hydraulic slag removal, and a spiral groove or a spiral rib \(3\) structure is not arranged on the surface of the drill pipe body \(1\).

[0021] The specific method for determining the rotary speed and the drilling speed of the drill rig in step (2) is as follows: When the formation firmness coefficient \(0 < f\leqslant0.3\), the rotary speed of the drill rig is designed to be \(200\mathrm{r / min}-360\mathrm{r / min}\), and the drilling speed is designed to be \(0.2\mathrm{m / min}-0.6\mathrm{m / min}\); When the formation firmness coefficient \(0.3 < f\leqslant0.8\), the rotary speed of the drill rig is designed to be \(150\mathrm{r / min}-200\mathrm{r / min}\), and the drilling speed is designed to be \(0.4\mathrm{m / min}-0.8\mathrm{m / min}\); When the formation firmness coefficient \(f > 0.8\), the rotary speed of the drill rig is designed to be \(150\mathrm{r / min}-200\mathrm{r / min}\), and the drilling speed is designed to be \(0.6\mathrm{m / min}-1\mathrm{m / min}\).

[0022] Embodiment 2 As Figure 4-5 shown, the difference from Embodiment 1 is whether a spiral groove or a spiral rib \(3\) is arranged on the drill pipe surface and the angles of the four arc segments of the square ring are different. There is no spiral groove or spiral rib \(3\) on the surface of the lightweight drill pipe in this embodiment, and a small angle treatment is adopted at the arc segment, further strengthening the overall strength of the drill pipe.

[0023] The above embodiments illustrate the basic principles and features of the present invention. However, the above only illustrates the preferred embodiments of the present invention and is not limited by the described embodiments. Those of ordinary skill in the art, inspired by this patent and without departing from the spirit of the present invention and the scope protected by the claims, can also make many forms of deformation and improvement, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be subject to the appended claims.

Claims

1. A lightweight drill pipe for drilling in complex formations, comprising a drill pipe body with a hollow structure, with female thread joints and male thread joints respectively provided at both ends of the drill pipe body, characterized in that: The cross-sectional shape of the drill pipe body is a square ring with circular arcs at all four corners. Along the axial direction of the drill pipe body, there are several spiral grooves or spiral ridges arranged in a circumferential array, and the spiral directions of all the spiral grooves or spiral ridges are the same.

2. The lightweight drill rod for drilling in complex formations according to claim 1 is characterized by: The distances between the outer sides and the inner sides of the opposite sides of the square ring are the outer side length H and the inner side length h respectively, and H is 1.2 to 3.2 times of h.

3. The lightweight drill rod for drilling in complex formations according to claim 2 is characterized by: The square ring includes four straight line segments and four arc segments that are alternately and closed-loop connected. The wall thickness b1 of the straight line segment is less than or equal to the wall thickness b2 of the arc segment, and the value range of the straight line wall thickness b1 is 5mm ≤ b1 ≤ 10mm.

4. A method for drilling a lightweight drill rod in a complex formation, using the drill rod as claimed in claim 3 for operation, characterized in that: It includes the following steps: (1). Determine different drill pipes according to the firmness coefficient f of the formation at the construction site; (2). Determine the rotary speed and drilling speed of the drill rig according to the firmness coefficient f of the formation at the construction site; (3). Arrange the drill rig, install the drill pipe, set up a dust removal device or a gas-water-sludge separation device at the hole opening, connect the drill pipe to the air pipe or water pipe, start the drill rig to drill, stop drilling after reaching the designed depth, and withdraw the drill pipe; (4). Move the drill rig to drill another hole; (5). Repeat steps (2) and (3).

5. The drilling method of a lightweight drill rod for drilling in complex formations according to claim 4, characterized in that: The specific method for determining different drill pipe structures in step (1) is as follows: When the formation firmness coefficient 0 < f ≤ 0.3, a spiral groove or spiral ridge structure is provided on the surface of the drill pipe body, and the depth of the spiral groove or the height of the spiral ridge on the surface of the drill pipe body is set to 2mm - 3.5mm; When the formation firmness coefficient 0.3 < f ≤ 0.8, a spiral groove or spiral ridge structure is provided on the surface of the drill pipe body, and the depth of the spiral groove or the height of the spiral ridge provided on the surface of the drill pipe body is set to 0.5mm - 2mm; When the formation firmness coefficient f > 0.8, drill using the hydraulic slag removal method, and no spiral groove or spiral ridge structure is provided on the surface of the drill pipe body.

6. The drilling method for a lightweight drill rod for drilling in complex formations according to claim 4 or 5, characterized in that: The specific method for determining the rotary speed and drilling speed of the drill rig in step (2) is as follows: When the formation firmness coefficient 0 < f ≤ 0.3, the rotary speed of the drill rig is designed to be 200 r / min - 360 r / min, and the drilling speed is designed to be 0.2 m / min - 0.6 m / min; When the formation firmness coefficient 0.3 < f ≤ 0.8, the rotary speed of the drill rig is designed to be 150 r / min - 200 r / min, and the drilling speed is designed to be 0.4 m / min - 0.8 m / min; When the formation firmness coefficient f > 0.8, the rotary speed of the drill rig is designed to be 150 r / min - 200 r / min, and the drilling speed is designed to be 0.6 m / min - 1 m / min.

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