Gas lift reverse circulation drilling structure

Abstract

The utility model discloses a gas lift reverse circulation drilling structure, and relates to the field of drilling. An annular space and an inner pipe on a double-arm driving drill rod are communicated with a double-wall drill rod in a matched mode respectively, the double-arm driving drill rod is connected with a gas faucet in a matched mode, a slag discharging through hole in the gas faucet is communicated with the inner pipe, the double-arm drill rod is connected with a matched conventional drill rod, the conventional drill rod is connected with a matched drill bit, and the drill bit is connected with the double-arm driving drill rod. The drill bit and the conventional drill rod are both provided with communicated center holes, the center holes are communicated with inner pipes on the double-wall driving drill rod and the double-wall drill rod, a water path is formed in the conventional drill rod, and the water path is communicated with annular gaps on the double-wall driving drill rod and the double-wall drill rod and communicated with jet holes in the drill bit. The double-wall drill rod has the advantages that gas-liquid mixtures carry rock debris in drilling, rise through the center holes of the drill bit and the conventional drill rod and are discharged through the inner pipe of the double-wall drill rod, it is guaranteed that the drill bit can effectively suck the rock debris at the bottom of the hole, sufficient water and upward returning speed are maintained, and the drill hole is prevented from being blocked.

Description

Technical Field

[0001] This utility model belongs to the field of drilling, specifically relating to an air-lift reverse circulation drilling structure. Background Technology

[0002] The air-lift reverse circulation drilling process cleverly utilizes compressed air to aerate the upper circulating medium (water), creating a density difference that generates a necessary pressure differential. This pressure differential effectively drives the lower circulating medium to flow upwards, thus forming a unique reverse circulation motion mode. The core of this drilling method lies in a meticulously designed reverse circulation drilling tool system, encompassing a series of key components such as the reverse circulation drill bit, conventional drill pipe, double-wall drill pipe, double-wall active drill pipe, air-water tee, slag discharge pipe, high-pressure air pipe, and air compressor, as well as other necessary auxiliary facilities.

[0003] In this system, the matching and coordination of drill strings are crucial. The reverse circulation drill bit is responsible for breaking the rock, while the conventional drill pipe connects the drill bit and the drilling rig, transmitting torque and bearing tensile forces. The design of the double-walled drill pipe is particularly unique, as an annulus is formed between its inner and outer tubes, providing a channel for the flow of compressed air and drilling fluid. The double-walled active drill pipe also possesses higher strength and stiffness to meet the high torque and high tensile force requirements during the drilling process.

[0004] It is worth noting that the gas lift reverse circulation drilling process has strict requirements on the return velocity. To ensure that cuttings can be effectively carried to the surface, the water return velocity must reach at least 3 m / s, while the gas return velocity must be no less than 15 m / s. More importantly, the velocity must remain stable throughout the entire return process, without any sudden changes. Sudden changes in velocity can prevent reverse circulation from forming, reduce reverse circulation efficiency, and even lead to serious problems such as stuck drill pipe or blockage. Utility Model Content

[0005] This invention addresses the technical problems of unstable upward return speed leading to the inability to form reverse circulation, as well as the issues of drill bit jamming and blockage. It provides an air-lift reverse circulation drilling structure. During drilling, the gas-liquid mixture carries rock cuttings, rises through the central hole of the drill bit and conventional drill pipe, and is discharged through the inner tube of the double-walled drill pipe. This ensures that the drill bit can effectively extract rock cuttings from the bottom of the hole, maintain sufficient water volume and upward return speed, and prevent borehole blockage.

[0006] The technical solution adopted by this utility model is as follows: An air-lift reverse circulation drilling structure is provided, including a double-walled active drill rod and a double-walled drill rod connected to a drilling rig. The annular gap and inner tube on the double-walled active drill rod are respectively connected to the matching tube on the double-walled drill rod. An air-water tap is connected to the double-walled active drill rod, and the slag discharge hole on the air-water tap is connected to the inner tube. A matching conventional drill rod is connected to the double-walled drill rod, and a matching drill bit is connected to the conventional drill rod. Both the drill bit and the conventional drill rod have a communicating central hole, which is connected to the inner tube on the double-walled active drill rod and the double-walled drill rod. A water passage is opened on the conventional drill rod, which is connected to the annular gap on the double-walled active drill rod and the double-walled drill rod, and also to the injection hole on the drill bit.

[0007] Compressed air is mixed with drilling fluid through a gas-water nozzle to form a gas-liquid mixture. This mixture is injected into the water passage of the conventional drill pipe through the annulus on the double-walled active drill pipe and the double-walled drill pipe, and then injected into the well through the injection hole on the drill bit. The gas-liquid mixture carries rock cuttings into the center hole on the drill bit and the conventional drill pipe, and rises and is discharged along the inner tube on the double-walled active drill pipe and the double-walled drill pipe. This ensures that the drill bit can effectively suck up rock cuttings from the bottom of the hole, maintain sufficient water volume and return speed, prevent borehole blockage, and thus ensure the safety and efficiency of the drilling process.

[0008] To further optimize this technical solution, the inner diameter of the central hole in the drill bit is 55mm-75mm.

[0009] When machining center holes for standard drill bits with a diameter of less than 245mm, the opening diameter of the center hole should be controlled between 55mm and 60mm. When machining center holes for standard drill bits with a diameter of more than 245mm, the opening diameter of the center hole should be controlled between 60mm and 70mm to ensure smooth slag removal without affecting the lubrication system of the standard drill bit.

[0010] To further optimize this technical solution, the ratio of the inner diameter of the central hole on the conventional drill rod to the inner diameter of the central hole on the drill bit is 1.2-1.5.

[0011] To avoid the inner diameter ratio being too small, which can easily cause blockage, and to avoid the inner diameter ratio being too large, which can reduce the upward return speed, it is necessary to ensure the air lift effect.

[0012] To further optimize this technical solution, the ratio of the inner diameter of the central hole on the conventional drill rod to the inner diameter of the inner tube on the double-walled drill rod is 1.2.

[0013] To further optimize this technical solution, when the inner diameter of the center hole on the drill bit is 55mm-60mm, the diameter of the air / water tap is not less than 70mm; when the inner diameter of the center hole on the drill bit is 60mm-75mm, the diameter of the air / water tap is not less than 80mm.

[0014] When the inner diameter of the center hole on the drill bit is 55mm-60mm, the diameter of the air / water tap should not be less than 70mm; when the inner diameter of the center hole on the drill bit is 60mm-75mm, the diameter of the air / water tap should not be less than 80mm.

[0015] To further optimize this technical solution, an angle steel plate is welded to the outer side of the drill bit's roller cone.

[0016] The angle steel plate welded to the outside of the drill bit's roller cone enhances structural strength, improves the drill bit's durability, and reduces the direct impact and wear of rocks on the roller cone.

[0017] To further optimize this technical solution, the thickness of the angle steel plate shall not be less than 1.8mm.

[0018] The beneficial effects of this utility model are as follows:

[0019] 1. The drill bit is modified from a conventional standard drill bit. By controlling the diameter of the double-walled active drill rod, double-walled drill rod, conventional drill rod, air-water tap, and drill bit within a reasonable range, the technical guarantee of air-lift reverse circulation drilling is ensured, which ensures efficient cuttings carrying and removal, effectively prevents borehole blockage, and improves drilling safety and efficiency.

[0020] 2. Suitable for drilling in relatively intact water-poor formations, it can significantly reduce construction costs and improve drilling efficiency. At the same time, it plays a role in washing the reservoir during the drilling process, effectively protecting the reservoir without blockage, thereby increasing the probability of well completion in water-poor areas and providing important support for water resource development and economic development.

[0021] 3. The angle steel plate welded to the outside of the drill bit cone significantly enhances the drill bit's durability, reduces wear, extends its service life, and can withstand high torque and high pressure working environments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the air-lift reverse circulation drilling structure in this embodiment;

[0023] Figure 2 This is a schematic diagram of the drill bit structure in this embodiment.

[0024] In the diagram, 1. Double-walled active drill rod; 2. Double-walled drill rod; 3. Annular gap; 4. Inner tube; 5. Air / water tap; 6. Conventional drill rod; 601. Water passage; 7. Drill bit; 701. Jet hole; 8. Center hole; 9. Angle steel plate. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] Please see the appendix Figure 1-2The air-lift reverse circulation drilling structure includes a double-walled active drill pipe 1, a double-walled drill pipe 2, and an air-water tap 5, all connected to the drilling rig. The air inlet of the air-water tap 5 is connected to an air compressor via a high-pressure air pipe, the water inlet is connected to a drilling fluid container via a pipeline, and the outlet is connected to a sedimentation tank via a slag discharge pipe. The annular gaps 3 and inner tubes 4 on both the double-walled active drill pipe 1 and the double-walled drill pipe 2 are connected. A matching conventional drill pipe 6 is connected to the double-walled drill pipe 2, and a matching drill bit 7 is connected to the conventional drill pipe 6. Both the drill bit 7 and the conventional drill pipe 6 have a central hole 8 that communicates with the inner cylinders of the double-walled active drill pipe 1 and the double-walled drill pipe 2. A water passage 601 is provided on the conventional drill pipe 6, which communicates with the annular gaps 3 on both the double-walled active drill pipe 1 and the double-walled drill pipe 2, and with the injection hole 701 on the drill bit 7. During drilling, high-pressure air and drilling fluid... After being mixed in the gas-water faucet 5, the mixture enters the water passage 601 of the conventional drill pipe 6 through the annular gap 3 on the double-walled active drill pipe 1 and the double-walled drill pipe 2. The water passage 601 is connected to the injection hole 701 on the drill bit 7, thereby spraying the gas-water mixture into the well. Then, it carries rock cuttings into the central hole 8 of the drill bit 7 and the conventional drill pipe 6, and moves upward along the inner tube 4 on the double-walled active drill pipe 1 and the double-walled drill pipe 2. It also enters the slag discharge pipe through the outlet on the gas-water faucet 5 and is injected into the sedimentation tank. During drilling operations, the drill bit 7 has an angle steel plate 9 welded to the outside of the roller cone, and the thickness of the angle steel plate 9 is not less than 1.8mm. The angle steel plate 9 enhances the structural strength of the outside of the roller cone of the drill bit 7, can resist the working environment of high torque and high pressure, and can reduce the direct impact and wear of rocks on the roller cone, extend the service life of the drill bit 7, and prevent large rocks from blocking the passage.

[0027] Drill bit 7 can be modified from a conventional standard drill bit 7. By removing the nozzle from the water eye on the standard drill bit 7, a jet hole 701 can be obtained, and a center hole 8 can be obtained by drilling a hole in the center of the standard drill bit 7. When machining the center hole 8 of a standard drill bit 7 with a diameter of less than 245mm, the opening diameter of the center hole 8 should be controlled between 55mm and 60mm. When machining the center hole 8 of a standard drill bit 7 with a diameter of more than 245mm, the opening diameter of the center hole 8 should be controlled between 60mm and 70mm to ensure that the center hole 8 has a smooth slag removal effect and does not affect the lubrication system of the standard drill bit 7.

[0028] When the opening diameter of the center hole 8 on the drill bit 7 is between 55mm and 60mm, it is equipped with a conventional drill rod 6 with a diameter of 89mm, a double-walled active drill rod 1 with an outer diameter of 127mm and a double-walled active drill rod 1 with an outer diameter of 133mm, and the through diameter of the air-water tap 5 is not less than 70mm. When the opening diameter of the center hole 8 on the drill bit 7 is between 60mm and 70mm, it is equipped with a conventional drill rod 6 with a diameter of 127mm, a double-walled active drill rod 1 with an outer diameter of 140mm and a double-walled active drill rod 1 with an outer diameter of 178mm, and the through diameter of the air-water tap 5 is not less than 80mm. This ensures that the drill bit 7 inlet can effectively suck up the rock cuttings at the bottom of the hole, while ensuring that enough water enters the drill rod. This also helps to form a stable gas-liquid mixture with sufficient upward return velocity, thereby effectively carrying the rock cuttings to the ground, preventing borehole blockage, and ensuring the safety and efficiency of the drilling process.

[0029] The ratio of the inner diameter of the center hole 8 on the conventional drill rod 6 to the inner diameter of the center hole 8 on the drill bit 7 should be controlled between 1.2 and 1.5 to avoid the inner diameter ratio being too small, which could easily cause blockage, and to avoid the inner diameter ratio being too large, which would reduce the upward return speed and ensure the air lift effect. In addition, the ratio of the inner diameter of the inner tube 4 of the double-wall drill rod 2 to the inner diameter of the center hole 8 on the conventional drill rod 6 should also be controlled at around 1.2 to provide technical support for air lift reverse circulation drilling.

[0030] The working principle of this air-lift reverse circulation drilling structure is as follows: By modifying the standard drill bit 7, a drill bit 7 with a specific diameter central hole 8 is formed, which is connected to the conventional drill pipe 6, double-walled active drill pipe 1, and double-walled drill pipe 2 with matching diameters. The annular gap 3 on the double-walled active drill pipe 1 and double-walled drill pipe 2 is connected to the water passage 601 on the conventional drill pipe 6 and the injection hole 701 on the drill bit 7. The central hole 8 is connected to the inner tube 4 of the double-walled active drill pipe 1 and double-walled drill pipe 2. The air-water faucet 5 acts as a mixer, mixing the compressed air delivered through the high-pressure air pipe with the drilling fluid delivered through the pipeline to form a gas-liquid mixture. The gas-liquid mixture is injected into the well through the injection hole 701 on the drill bit 7, and carries the rock cuttings through the central hole 8 of the drill bit 7 and the conventional drill pipe 6, as well as the inner tube 4 of the double-walled drill pipe 2, moving upward to achieve effective removal of rock cuttings. Furthermore, the angle steel plate 9 welded to the outside of the drill bit 7's roller cone enhances structural strength, improves the durability of the drill bit 7, and reduces direct impact and wear from rocks on the roller cone. The entire system design ensures that the drill bit 7 can effectively extract rock cuttings from the bottom of the hole, maintain sufficient water volume and return speed, and prevent borehole blockage, thereby ensuring the safety and efficiency of the drilling process. It is also effective for drilling in relatively intact, water-poor formations, significantly reducing construction costs and increasing drilling efficiency by more than double, while effectively protecting the water-bearing reservoir. Because this drilling process is also a well-washing process, it only clears the formation without causing blockage, increasing the probability of well success in water-poor areas.

Claims

1. A gas-lift reverse circulation drilling structure, comprising a double-walled active drill rod (1) and a double-walled drill rod (2) connected to a drilling rig, wherein the annular gap (3) and inner tube (4) on the double-walled active drill rod are respectively connected to the matching tube on the double-walled drill rod (2), and an air-water tap (5) is connected to the double-walled active drill rod, wherein the slag discharge through hole on the air-water tap (5) is connected to the inner tube (4), and a matching conventional drill rod (6) is connected to the double-walled drill rod, characterized in that: The conventional drill rod (6) is connected to a matching drill bit (7). Both the drill bit (7) and the conventional drill rod (6) are provided with a central hole (8). The central hole (8) is connected to the inner tube (4) on the double-walled active drill rod (1) and the double-walled drill rod (2). A water passage (601) is opened on the conventional drill rod (6). The water passage (601) is connected to the annular gap (3) on the double-walled active drill rod (1) and the double-walled drill rod (2), and is connected to the jet hole (701) on the drill bit (7).

2. The air-lift reverse circulation drilling structure according to claim 1, characterized in that: The inner diameter of the center hole (8) on the drill bit (7) is 55mm-75mm.

3. The air-lift reverse circulation drilling structure according to claim 2, characterized in that: The ratio of the inner diameter of the center hole (8) on the conventional drill rod (6) to the inner diameter of the center hole (8) on the drill bit (7) is 1.2-1.

5.

4. The air-lift reverse circulation drilling structure according to claim 3, characterized in that: The ratio of the inner diameter of the center hole (8) on the conventional drill rod (6) to the inner diameter of the inner tube (4) on the double-walled drill rod (2) is 1.2-1.

5.

5. The air-lift reverse circulation drilling structure according to claim 2, characterized in that: When the inner diameter of the center hole (8) on the drill bit (7) is 55mm-60mm, the diameter of the air-water tap (5) is not less than 70mm. When the inner diameter of the center hole (8) on the drill bit (7) is 60mm-75mm, the diameter of the air-water tap (5) is not less than 80mm.

6. The air-lift reverse circulation drilling structure according to claim 1, characterized in that: An angle steel plate (9) is welded to the outside of the roller cone of the drill bit (7).

7. The air-lift reverse circulation drilling structure according to claim 6, characterized in that: The thickness of the angle steel plate (9) is not less than 1.8 mm.

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