A friction-reducing and drag-reducing device for gas drilling

Abstract

This invention provides a friction-reducing and drag-reducing device for gas drilling, comprising a body with a first groove on its outer wall, forming a channel for fluid flow connecting both ends of the body. The channel is spiral-shaped, allowing the fluid flowing through it to form a continuous and stable turbulent field. The channel includes a first flow path spiraling clockwise and a second flow path spiraling counterclockwise, arranged alternately to form a biomimetic double-helix flow path. This friction-reducing and drag-reducing device for gas drilling effectively reduces frictional resistance during gas drilling and improves the gas's rock-carrying capacity.

Description

Technical Field

[0001] This invention relates to the field of oilfield development, and more specifically to a friction-reducing and drag-reducing device for gas drilling. Background Technology

[0002] Gas drilling technology has been increasingly widely used in oilfield development. This technology uses compressed air as both the circulating medium and the energy source for breaking rocks, and it offers advantages such as fast drilling speed, simple equipment, and high safety.

[0003] However, for oil wells with large inclination angles, long inclined sections, and significant horizontal displacement, gas drilling technology presents challenges in carrying cuttings with the gas, making it difficult to bring the cuttings out of the well. Consequently, cuttings tend to accumulate at the bottom edge of the wellbore, forming cuttings beds of considerable length and height. These cuttings beds, in turn, increase frictional torque during drilling, severely limiting drilling operations.

[0004] To address the engineering challenge of high frictional torque caused by cuttings beds, patent CN105221074B discloses a friction-reducing joint. This joint generates a water hammer effect by periodically expanding and contracting the overlapping area of ​​the rotor and stator, causing the drill string to vibrate and thus reducing frictional resistance. However, this friction-reducing joint is only suitable for conventional drilling fluid conditions and not for gas drilling conditions.

[0005] Patent CN206190211U discloses a friction-reducing and resistance-lowering joint. This joint achieves friction reduction and resistance lowering through the sliding friction of the rollers; however, rock cuttings easily get stuck between the rollers and the steering seat, preventing the rollers from rotating and thus failing to achieve the friction-reducing and resistance-lowering effect. Furthermore, this joint does not have the function of clearing rock cuttings beds in inclined shaft sections.

[0006] Patent CN205977126U discloses a friction-reducing tool. This tool reduces friction during drill string rotation, running-in, and sliding drilling. However, cuttings beds in deviated well sections can easily get stuck between the steel ball and the ball sleeve, thus affecting the friction-reducing function. Furthermore, this friction-reducing tool does not have the effect of breaking up the cuttings bed or increasing the annular fluid's ability to carry rock. Summary of the Invention

[0007] To address the technical problems described above, this invention aims to provide a friction-reducing and drag-reducing device for gas drilling. This device effectively reduces frictional resistance during gas drilling and improves the gas's rock-carrying capacity.

[0008] According to the present invention, a friction-reducing and drag-reducing device for gas drilling is provided, comprising: a body, wherein a first groove is provided on the outer wall of the body, the first groove being formed as a channel for fluid flow connecting the two ends of the body.

[0009] The channel is spiral-shaped, allowing the fluid flowing through it to form a continuous and stable turbulent field. The channel includes a first flow channel that spirals clockwise and a second flow channel that spirals counterclockwise, with the first and second flow channels arranged alternately to form a biomimetic double-helix flow channel.

[0010] In a preferred embodiment, the cross-section of the first groove is set to be approximately semi-circular, the width of the first groove is set to 5cm-10cm, the depth is set to 2.3cm-4.5cm, and the angle between the axis of the first groove and the axis of the body is set to 25°-55°.

[0011] In a preferred embodiment, the system further includes a plurality of second grooves, which are evenly arranged radially along the body on the sidewall of the first groove.

[0012] In a preferred embodiment, the second groove is arranged in a direction that gradually moves away from the radial center of the body along the direction of fluid flow.

[0013] In a preferred embodiment, at least one baffle is further provided on the sidewall of the first groove, the baffle being arranged downstream of the second groove.

[0014] In a preferred embodiment, a plurality of cutting teeth are evenly arranged on the outer wall of the body.

[0015] In a preferred embodiment, the cutting tooth is rhomboid in shape, and the top surface of the cutting tooth away from the body is set as an arc surface.

[0016] In a preferred embodiment, the tooth height of the cutting tooth is set to 0.3cm-1cm, the side length is set to 0.7cm-2.1cm, and the radius of curvature of the top surface is set to 15-30cm. Within this size range, a variety of cutting teeth of different sizes are provided.

[0017] In a preferred embodiment, 8-12 cutting teeth are arranged per 360° spiral.

[0018] In a preferred embodiment, the cutting teeth are arranged such that the direction of one diagonal of the rhombus is parallel to the direction of the channel. Attached Figure Description

[0019] The invention will now be described with reference to the accompanying drawings.

[0020] Figure 1 A schematic diagram of a friction-reducing and drag-reducing device for gas drilling according to an embodiment of the present invention is shown.

[0021] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0022] The invention will now be described with reference to the accompanying drawings.

[0023] Figure 1 A friction-reducing and drag-reducing device 100 for gas drilling according to an embodiment of the present invention is shown. Figure 1 As shown, the friction-reducing and drag-reducing device 100 for gas drilling includes a body 10 connected to a drill string (not shown), the body 10 being cylindrical in shape. A first groove 20 is also provided on the outer wall of the body 10. The first groove 20 extends from a first end 12 to a second end 14 of the body 10, thereby allowing downhole fluid to pass through the body 10 along the first groove 20, thus forming a fluid flow channel 30 connecting the first end 12 and the second end 14 of the body 10.

[0024] like Figure 1 As shown, the channel 30 is constructed in a spiral shape, extending from the first end 12 of the body 10 to the second end 14. This configuration allows the direction of fluid flow to be continuously changed as the fluid flows along the channel 30, thereby enabling the fluid flowing through the channel 30 to form a continuous and stable turbulent flow field.

[0025] It is easy to understand that, compared to a flat flow, creating turbulence in the downhole fluid can improve its cuttings carrying capacity, thereby preventing the rock cuttings generated during drilling from depositing at the bottom edge of the wellbore and forming a new cuttings bed. This, in turn, prevents the newly formed cuttings bed from hindering the rotation of the drill string, thus reducing drilling friction.

[0026] In an embodiment not shown, the channel 30 is configured to include a first flow channel that rotates clockwise and a second flow channel that rotates counterclockwise. The first and second flow channels are arranged alternately on the outer wall of the body 10, thereby forming an approximate biomimetic double-helix flow channel. This configuration can further enhance the turbulence field formed by the fluid flowing through the channel 30, thereby further improving the fluid's rock-carrying capacity.

[0027] In this invention, the cross-section of the first groove 20 is preferably set to be approximately semi-circular, so that the bottom of the channel 30 has a certain curvature. Compared with a square groove, this first groove 20 with a curved bottom is more conducive to the rotation of fluid within the first groove 20, thereby making it more conducive to the formation of turbulence within the first groove 20.

[0028] Meanwhile, the width of the first groove 20 is set to 5cm-10cm, the depth is set to 2.3cm-4.5cm, and the angle between the axis of the first groove 20 and the axis of the body is set to 25-55°. Extensive engineering experiments conducted by the inventors have shown that the size and arrangement angle of this first groove 20 enable the fluid to have better rock-carrying capacity.

[0029] like Figure 1 As shown, the friction-reducing and drag-reducing device 100 for gas drilling of the present invention further includes a second groove 40. The second groove 40 is disposed on the sidewall 22 of the first groove 20. The second groove 40 can change the width of the first groove 20 at different positions in the radial direction of the body 10. This causes different flow velocities between different flow layers of fluid flowing through the second groove 40, thereby further disrupting the laminar flow state of the fluid stratification and forming turbulence. Preferably, a plurality of second grooves 40 are disposed on the sidewall 22 of the first groove 20, and the plurality of second grooves 40 are arranged radially along the body 10, thereby further improving the effect of the second grooves 40 in disrupting the laminar flow state of the fluid.

[0030] like Figure 1 As shown, in a preferred embodiment, the second groove 40 is arranged obliquely on the sidewall of the first groove 20. This allows the second groove 40 to change the flow direction of the fluid in the radial direction of the body 10, thus acting as a flow divider and further increasing the mutual influence between different fluid layers, which is more conducive to the formation of turbulence and improves the fluid's rock-carrying capacity.

[0031] Furthermore, the second groove 40 is arranged in a direction that gradually moves away from the radial center of the body 10 along the direction of fluid flow. Thus, as the fluid flows through the channel 30, the second groove 40 can force the fluid in the lower (i.e., the side closer to the radial center of the body) flow layer to continuously flow upward (i.e., the side away from the radial center of the body) flow layer, and cause the rock fragments carried by the fluid to continuously move away from the radial center of the body.

[0032] This design allows the second groove 40 to lift rock cuttings. This, in turn, allows the fluid to carry the rock cuttings to the annulus between the body 10 and the wellbore, preventing rock cuttings from depositing at the bottom of the first groove 20 and further enhancing the fluid's rock-carrying capacity.

[0033] In a preferred embodiment, at least one flow-deflecting element 25 is further provided on the sidewall 22 of the first groove 20. The flow-deflecting element 25 is constructed as a protrusion extending from the sidewall 22. It is readily understood that the flow-deflecting element 25 can impede the normal flow of fluid within the first groove 20, disrupting the laminar flow state of the fluid and thus promoting turbulent flow. Preferably, the flow-deflecting element 25 is arranged downstream of the second groove 40. This allows the fluid to pass through the second groove 40 first before being turbulent, thereby preventing the flow-deflecting element 25 from affecting the flow-diverting effect of the second groove 40.

[0034] like Figure 1 As shown, multiple cutting teeth 50 are evenly arranged on the outer wall of the body 10. These cutting teeth 50 can simultaneously break up the cuttings bed on the wellbore during the rotation of the body 10, preventing the cuttings bed from obstructing the normal movement of the body 10 and the downhole drill string (not shown), thereby reducing friction and drag. Furthermore, the cutting teeth 50 can grind downhole cuttings, reducing their diameter and making it easier for them to be carried out of the wellbore.

[0035] Simultaneously, the contact between the cutting teeth 50 and the downhole cuttings bed allows the cuttings bed to support the body 10, preventing the horizontally or inclined body 10 from directly contacting the well wall under gravity. Thus, the cutting teeth 50 serve two purposes: firstly, they maintain a certain distance between the body 10 and the well wall, ensuring sufficient space for the downhole fluid to carry the cuttings; secondly, they prevent direct friction between the body 10 and the well wall during downhole movement, thereby reducing the frictional resistance experienced by the body 10 downhole.

[0036] In a preferred embodiment, the cutting tooth 50 is rhomboid in shape, with its top surface 52, furthest from the main body, being an arc surface, to ensure better grinding effect on downhole cuttings. Simultaneously, the tooth height of the cutting tooth is set to 0.3cm-1cm, the side length to 0.7cm-2.1cm, and the radius of curvature of the arc surface to 15cm-30cm. Field engineering practice shows that cutting teeth 50 within this size range have a better destructive effect on downhole cuttings beds.

[0037] In a preferred embodiment, the number of cutting teeth is set to 8-12 per 360° spiral, and the multiple cutting teeth 50 are evenly arranged on the outer wall of the body 10. It should be noted that within this size and quantity range, operators can also set various sizes and curvatures of cutting teeth 50, thereby further enhancing the destructive effect of the cutting teeth 50 on the cuttings bed.

[0038] like Figure 1As shown, in a preferred embodiment, the cutting teeth 50 are arranged such that the direction of any one of their diagonals is parallel to the direction of the channel 30. This reduces wear between the drill string and the downhole casing during drilling, thereby increasing the service life of both the casing and the drill string.

[0039] In addition, multiple friction-reducing and drag-reducing devices 100 described above for gas drilling can be installed between the drill string during the drilling process to achieve better friction-reducing and drag-reducing effects. Field tests show that for common long inclined wells with an inclination angle greater than 35°, a length of inclined section exceeding 2400m, and a horizontal displacement exceeding 1400m, setting the number of friction-reducing and drag-reducing devices 100 to one every 80-120m achieves a relatively ideal friction-reducing and drag-reducing effect, which can meet engineering requirements.

[0040] The working process of the friction reduction and drag reduction device 100 for gas drilling according to the present invention is briefly described below.

[0041] When performing long-angle gas drilling operations, the friction-reducing and drag-reducing device 100 for gas drilling of this invention can be connected between the drill string and lowered into the well along with the drill string. As the drilling process proceeds, the cutting teeth 50 on the outside of the body 10 can break up the cuttings bed on the well wall, preventing friction between the cuttings bed and the drill string, and between the cuttings bed and the body 10, which would increase drilling friction. At the same time, the cutting teeth 50 can also grind the cuttings, thereby reducing the particle size of the cuttings and making it easier for the downhole cuttings to be carried out of the wellhead by the fluid.

[0042] When fluid carrying rock fragments flows through the channel 30, the biomimetic double-helix structure of the channel 30 enables the fluid to form a stable turbulent flow field, thereby further improving the fluid's rock-carrying effect. Simultaneously, the second groove 40 also allows the fluid to lift the rock fragments, preventing rock fragments from depositing within the channel 30, thus further enhancing the fluid's rock-carrying efficiency.

[0043] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A friction-reducing and drag-reducing device (100) for gas drilling, comprising: The body (10) has a first groove (20) on its outer wall. The first groove is formed as a channel (30) for fluid flow connecting both ends of the body. A plurality of second grooves are provided on the side wall of the first groove. The plurality of second grooves are configured to change the width of the first groove at different positions in the radial direction of the body. At least one flow-disrupting element is also provided on the side wall of the first groove. The flow-disrupting element is arranged downstream of the second groove. The channel is spiral-shaped, allowing the fluid flowing through it to form a continuous and stable turbulent field. The channel includes a first flow channel that spirals clockwise and a second flow channel that spirals counterclockwise, with the first and second flow channels arranged alternately to form a biomimetic double-helix flow channel. The second groove is inclinedly arranged on the side wall of the first groove, and the arrangement direction of the second groove is set to gradually move away from the radial center of the body along the direction of fluid flow.

2. The friction reduction and drag reduction device (100) for gas drilling according to claim 1, characterized in that, The cross-section of the first groove is set to be approximately semi-circular, the width of the first groove is set to 5cm-10cm, the depth is set to 2.3cm-4.5cm, and the angle between the axis of the first groove and the axis of the body is set to 25°-55°.

3. The friction-reducing and drag-reducing device (100) for gas drilling according to claim 1 or 2, characterized in that, The plurality of second grooves are evenly arranged along the radial direction of the body on the sidewall of the first groove.

4. The friction-reducing and drag-reducing device (100) for gas drilling according to claim 1 or 2, characterized in that, Multiple cutting teeth (50) are evenly arranged on the outer wall of the body.

5. The friction reduction and drag reduction device (100) for gas drilling according to claim 4, characterized in that, The cutting tooth is rhomboid in shape, and the top surface (52) of the cutting tooth away from the body is set as an arc surface.

6. The friction reduction and drag reduction device (100) for gas drilling according to claim 5, characterized in that, The cutting teeth have a tooth height of 0.3cm-1cm, a side length of 0.7cm-2.1cm, and a top surface radius of curvature of 15cm-30cm. Within this size range, there are various sizes of cutting teeth.

7. The friction reduction and drag reduction device (100) for gas drilling according to claim 6, characterized in that, Each spiral has 8-12 cutting teeth arranged in a 360° configuration.

8. The friction reduction and drag reduction device (100) for gas drilling according to claim 7, characterized in that, The cutting teeth are arranged such that the direction of one diagonal of the rhombus is parallel to the direction of the channel.

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