Reverse circulation anti-blocking drill bit and gas lift reverse circulation drilling system

Abstract

The invention relates to the technical field of drilling, in particular to a reverse circulation anti-blocking drill bit and a gas lift reverse circulation drilling system.The reverse circulation anti-blocking drill bit comprises a drill bit body, a first flow channel and a second flow channel are arranged in the drill bit body and are in a streamline shape, and the diameter of a lower port of the first flow channel is smaller than that of an upper port of the first flow channel; the reverse circulation drill bit is not easy to block during working, so that the phenomenon of blockage of the drill bit is effectively avoided; when the gas lift reverse circulation drilling system adopts the reverse circulation anti-blocking drill bit, the drilling efficiency of the gas lift reverse circulation drilling system can be effectively guaranteed due to the fact that the drill bit is not prone to blocking.

Description

Technical Field

[0001] The invention relates to the technical field of drilling, and in particular to a reverse circulation anti-blocking drill bit and a gas lift reverse circulation drilling system. Background Art

[0002] Compared with the positive circulation drilling technology, the difference between the reverse circulation drilling technology and the positive circulation drilling technology is that the flow direction of the mud in the drill pipe is different. The positive circulation means that the mud flows from top to bottom in the drill pipe, and after reaching the bottom of the hole, it carries the drill cuttings through the pile hole to the sedimentation tank at the hole mouth. The reverse circulation is just the opposite. The mud flows from bottom to top in the drill pipe. The mud is carried by the drill bit along the drill pipe from bottom to top into the sedimentation tank as soon as the drill bit discharges the cuttings. Therefore, compared with the positive circulation drilling technology, the reverse circulation drilling technology has a high hole-forming efficiency, which is especially suitable for shallow wells with large diameters, and is conducive to the efficient sand carrying of ultra-large-sized wellbores, the prevention and control of leaks in sections with malignant well leakage, and the effective protection of sensitive reservoirs.

[0003] However, the roller bit used in the reverse circulation drilling technology is based on the positive circulation roller bit. A 40-50 mm slag inlet is drilled in the middle of the three rollers. The slag inlet is connected with the three original side water channels of the roller bit to form a channel for the return of cuttings. However, in the actual drilling and single-root connection process, since the slag inlet is linear and the three side water channels are small in size, it is very easy to block the drill, affecting the construction. Summary of the invention

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a reverse circulation anti-blocking drill bit and an air lift reverse circulation drilling device. A streamlined first flow channel is arranged in the drill bit body, and the first flow channel serves as a main slag discharge channel. The diameter of the lower port of the first flow channel is larger than the diameter of the upper port. When in use, the large-diameter lower port is close to the bottom of the well, which is easy to return and not easy to be blocked, thereby solving the technical problem of easy blockage of the linear slag discharge channel in the prior art.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A reverse circulation anti-blocking drill bit, comprising:

[0007] A drill bit body, the upper end of which is used to connect to the drill rod;

[0008] The first flow channel is streamlined and arranged at the center of the drill body. The first flow channel penetrates the drill body from top to bottom, and the size of the lower port is larger than the size of the upper port.

[0009] A second flow channel is obliquely disposed in the drill body, and its axis intersects with the axis of the first flow channel;

[0010] The upper port of the second flow channel is connected to the middle part of the first flow channel, and the lower port is located at the lower end of the drill body.

[0011] Furthermore, the inner diameter of the upper port of the first flow channel is consistent with the inner diameter of the drill pipe, and the cross-sectional shape of the lower port is trumpet-shaped.

[0012] Further, at least three teeth are provided at the lower end of the drill body, and the number of the second flow channels is at least three;

[0013] At least three second flow channels are respectively located in the drill bit body between two adjacent tooth palms.

[0014] Further, the diameter of the upper port of the second flow channel is greater than the diameter of the lower port of the second flow channel, and the area of ​​the water flow cross section of the upper port of the second flow channel is greater than or equal to the area of ​​the water flow cross section of the first flow channel.

[0015] Further, the second flow channel includes:

[0016] A transition section, located at an upper end of the second flow channel and connected to the first flow channel;

[0017] The guide section is located at the lower port of the second flow channel and is smoothly connected with the transition section. The guide section is cylindrical.

[0018] Preferably, the cross-sectional shape of the transition section is bowl-shaped.

[0019] Preferably, the cross-sectional shape of the transition section is trumpet-shaped.

[0020] Preferably, the cross-sectional shape of the transition section is an inverted cone.

[0021] Furthermore, the outer ring of the first end of the drill bit body is provided with an external thread, and the drill bit body can be connected to the drill rod through the external thread.

[0022] The present application also provides a gas lift reverse circulation drilling system, comprising the above-mentioned reverse circulation anti-blocking drill bit.

[0023] The beneficial effects of the present invention are:

[0024] The reverse circulation anti-blocking drill bit and the gas lift reverse circulation drilling system provided by the present invention fill the gap in the prior art.

[0025] The present invention provides a reverse circulation anti-blocking drill bit, wherein a streamlined first flow channel is arranged at the center of the drill bit body, and the diameter of the lower port of the first flow channel is larger than the diameter of the upper port. When in use, the lower port of the first flow channel is close to the bottom of the well, and the flushing fluid carries rock powder from the drilling annulus gap into the first flow channel of the drill bit, and brings the rock cuttings generated during the drilling process to the ground through the first flow channel and the second flow channel on the drill bit body. Compared with conventional roller drill bits, the streamlined structure of the first flow channel and the setting of the lower port size larger than the upper port size make it easy for the rock cuttings to return and not easy to be blocked.

[0026] The present invention also provides an air lift reverse circulation drilling system. By adopting the above reverse circulation anti-blocking drill bit, rock cuttings are easy to return and not easy to be blocked, which can effectively avoid the occurrence of drill blockage and thus improve the drilling efficiency of the air lift reverse circulation drilling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0028] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0029] Figure 1 It is a top view of a reverse circulation anti-blocking drill bit in a specific implementation manner;

[0030] Figure 2 for Figure 1 AA section view of the medium reverse circulation anti-blocking drill bit;

[0031] Figure 3 for Figure 2 A schematic diagram of a partial structure of a first example of a second flow channel;

[0032] Figure 4 for Figure 2 A schematic diagram of a partial structure of a second example of a second flow channel;

[0033] Figure 5 for Figure 2 A schematic diagram of a partial structure of a third example of the second flow channel;

[0034] Figure 6 It is a schematic diagram of the flow direction of cuttings of a reverse circulation anti-blocking drill bit in a specific implementation manner;

[0035] FIG. 7 is a schematic structural diagram of a gas lift reverse circulation drilling system in a specific implementation manner.

[0036] Reference numerals: A, reverse circulation anti-blocking drill bit;

[0037] 1. drill bit body; 110. first flow channel; 120. second flow channel; 121. transition section; 122. flow guide section; 130. external thread; 140. tooth palm;

[0038] 2. Air compressor; 3. Air and water faucet; 4. Gas-liquid mixer; 5. Double-wall drill pipe; 6. Single-wall drill pipe; 7. Slag discharge pipe; 8. Sedimentation tank; 9. Drilling. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0040] In the description of this embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the scope of protection of this embodiment.

[0041] Reverse circulation drilling technology uses pressure difference to carry cuttings from the bottom of the well to the wellhead through the drill pipe through mud, and then injects them into the bottom of the well again after being processed by separation equipment. Reverse circulation drilling technology can avoid high pressure in the drill pipe, thereby reducing the risk of wellbore rupture. At the same time, since the mud is discharged through the wellhead, the wellhead equipment is better protected. Therefore, it is widely used in the drilling of horizontal wells, deep wells and high-density wells.

[0042] At present, the roller drill bit used in reverse circulation drilling technology is based on the positive circulation roller drill bit. A 40-50 mm slag inlet is drilled in the middle of the three rollers. The slag inlet is connected with the three original side water holes of the roller drill bit to form a channel for the return of cuttings.

[0043] However, in the actual drilling and single-root connection process, since the slag inlet is linear and the three water eye flow channels on the side are small in size, drill blockage is very likely to occur, affecting construction efficiency.

[0044] This application is based on the above-mentioned problems existing in the prior art, such as Figure 1 , Figure 2 and Figure 6 As shown, this embodiment provides a reverse circulation anti-blocking drill bit A and a gas lift reverse circulation drilling system.

[0045] The reverse circulation anti-blocking drill bit A comprises a drill body 1, and the upper end of the drill body 1 is used to connect with the drill pipe. The drill body 1 is provided with a first flow channel 110 and a second flow channel 120. The first flow channel 110 is streamlined, arranged at the center of the drill body 1, and penetrates the drill body 1 from top to bottom. The upper port size of the first flow channel 110 is equal to the inner diameter of the drill pipe, and the lower port size is larger than the upper port size.

[0046] The second flow channel 120 is obliquely arranged in the drill bit body 1, and its axis intersects with the axis of the first flow channel 110. The upper port of the second flow channel 120 is connected to the middle part of the first flow channel 110, and the lower port is located at the lower end of the drill bit body 1. The second flow channel 120 can be used as a flow channel for mud, gas and small-particle rock cuttings. The setting of the second flow channel 120 can reduce the slag discharge pressure of the first flow channel 110, thereby effectively reducing the occurrence of drill blockage.

[0047] In a preferred exemplary embodiment, the diameter of the upper port of the first flow channel 110 is the same as the inner diameter of the drill rod, and the cross-sectional shape is trumpet-shaped, and the large end of the trumpet-shaped structure is located at the lower end of the drill body.

[0048] Firstly, the trumpet-shaped structure meets the streamlined structural design requirements of the first flow channel 110 on the one hand, so that the cuttings can flow smoothly into the first flow channel 110, while reducing the wear of the cuttings on the inner wall of the first flow channel 110; on the other hand, it can also accelerate the mud and cuttings in the first flow channel 110 to increase the flow speed of the mud and cuttings, which can further avoid the occurrence of blockage.

[0049] Secondly, the diameter of the upper port of the first flow channel 110 is the same as the inner diameter of the drill pipe, which is the limit value of the diameter of the first flow channel 110 and can minimize the blockage of the first flow channel 110 caused by mud and cuttings.

[0050] When in use, the upper end of the drill bit body 1 is connected to the drill pipe, and the lower end is close to the bottom of the well. The first flow channel 110 serves as the main slag discharge channel. Under the action of the pressure difference, a large amount of mud carrying rock cuttings flows into the first flow channel 110 from the lower port, and a small amount of mud carrying small-particle rock cuttings flows into the first flow channel 110 through the second flow channel 120, and then flows into the drill pipe from the upper port of the first flow channel 110. Due to the setting of the second flow channel 120, the size of the lower port of the first flow channel 110 is larger than the size of the upper port, and its streamlined structural design, the mud and rock cuttings can flow smoothly into the first flow channel 110, are easy to return and are not easy to be blocked, thereby effectively avoiding the occurrence of drilling blockage, thereby ensuring construction efficiency.

[0051] In this embodiment, at least three tooth palms 140 are provided at the lower end of the drill bit body 1, and the tooth palms 140 are respectively used to connect cutting teeth. When the drill bit body 1 rotates, the cutting teeth cut the surrounding soil to achieve the purpose of drilling.

[0052] The number of the second flow channels 120 matches the number of the teeth legs 140 , which is also at least three. At least three second flow channels 120 are respectively located in the drill body 1 between two adjacent teeth legs 140 .

[0053] It can be understood that the all-round arrangement of at least three second flow channels 120 allows the rock cuttings and mud cut between the drill bit body 1 and the annulus to be pressed into the second flow channel 120 in time, and then discharged through the second flow channel 120, the first flow channel 110 and the drill rod in turn, so as to filter and separate the mixture of mud and rock cuttings in time to improve drilling efficiency.

[0054] Furthermore, in this embodiment, the diameter of the upper port of the second flow channel 120 is larger than the diameter of the lower port of the second flow channel 120 , and the area of ​​the water flow cross section of the upper port of the second flow channel 120 is larger than or equal to the area of ​​the water flow cross section of the first flow channel 110 .

[0055] Here, the water-passing cross section of the upper end of the second flow channel 120 refers to the area of ​​the intersection surface between the upper end of the second flow channel 120 and the first flow channel 110, and the water-passing cross section of the first flow channel 110 refers to the cross section of the first flow channel 110, that is, the area of ​​the circular cross section. The area of ​​the water-passing cross section of the upper end of the second flow channel 120 is set to be greater than or equal to the area of ​​the water-passing cross section of the first flow channel 110, in order to enable the slurry in the second flow channel 120 to flow smoothly into the first flow channel 110, thereby reducing the flow resistance of the slurry in the second flow channel 120.

[0056] Secondly, the diameter of the upper port of the second flow channel 120 is set larger than the diameter of the lower port of the second flow channel 120, so that the large-grained rock cuttings in the first flow channel 110 will not block the upper port of the second flow channel 120, so that the mud and rock cuttings in the second flow channel 120 can flow smoothly into the first flow channel 110, which can effectively avoid the occurrence of drill blockage.

[0057] Specifically in this embodiment, Figure 3 , Figure 4 and Figure 5 As shown, the second flow channel 120 includes a transition section 121 and a guide section 122. The transition section 121 is located at the upper end of the second flow channel 120 and is connected to the first flow channel 110. The guide section 122 is located at the lower end of the second flow channel 120 and is smoothly connected to the transition section 121. The guide section 122 is cylindrical and its diameter is smaller than that of the transition section 121.

[0058] It can be understood that in the present embodiment, the segmented structure of the second flow channel 120 is set, that is, the guide section 122 and the transition section 121 are set, the water flow cross-sectional area of ​​the transition section 121 is greater than or equal to the water flow cross-sectional area of ​​the first flow channel 110, and the diameter of the guide section 122 is smaller, the purpose is to ensure the smoothness of the second flow channel 120 while avoiding the drill body 1 from being hollowed out as much as possible. If the diameter of the guide section 122 is the same as the diameter of the transition section 121 or the first flow channel 110, the drill body 1 will be hollowed out in a large volume, which will greatly affect the use strength and life of the drill bit.

[0059] like Figure 3 As shown, in the first exemplary embodiment, the cross-sectional shape of the transition section 121 is bowl-shaped, the bowl mouth of the bowl-shaped structure is connected to the first flow channel 110, the cross-sectional shape of the bowl mouth is elliptical, and the bowl bottom is smoothly connected to the guide section 122. The streamlined shape of the bowl-shaped structure can reduce flow resistance, and the unique design of the elliptical nozzle at the bowl mouth is less prone to clogging in extreme environments, and can ensure continuous operation under high flow rates, which is particularly important for carrying large-size rock cuttings particles.

[0060] like Figure 4 As shown, in the second exemplary embodiment, the cross-sectional shape of the transition section 121 is trumpet-shaped, one end of the trumpet mouth is connected to the first flow channel 110, and the end away from the trumpet mouth is smoothly transitioned to the guide section 122. In this embodiment, the trumpet-shaped structure of the transition section 121 is streamlined and has a smooth appearance, which can reduce flow resistance and significantly reduce pressure loss during the flow process, thereby improving the flow efficiency of the drilling fluid and accelerating the carrying of cuttings.

[0061] like Figure 5 As shown, in the third exemplary embodiment, the cross-sectional shape of the transition section 121 is an inverted cone, the large end of the inverted cone structure is connected to the first flow channel 110, and the small end is connected to the guide section 122. In the embodiment, the transition section 121 is conical, which can produce high-speed fluid, so that the drilling fluid is accelerated in the second flow channel 120 to reach a higher flow rate. According to the dynamic principle of fluid, this acceleration effectively improves the kinetic energy of the fluid to produce a better rock carrying effect.

[0062] Here, the cross-sectional shape of the transition section 121 is not limited to the above three examples. In actual use and operation, while ensuring that the water flow cross-sectional area of ​​the transition section 121 is greater than or equal to the water flow cross-sectional area of ​​the first flow channel 110, the cross-sectional shape of the transition section 121 can be adaptively adjusted according to the operating conditions, and all of these are within the protection scope of the present invention, and this embodiment will not make any specific limitations.

[0063] In the disclosed embodiment, the outer ring of the upper end of the drill bit body 1 is also provided with an external thread 130, and the drill bit body 1 can be connected to the drill rod through the external thread 130. The external thread 130 is a tapered thread, and the corresponding inner ring of the drill rod is also a tapered thread. The tapered thread connection method has good sealing performance and can prevent the slurry in the drill rod from flowing out during connection. Secondly, the threaded connection method between the drill bit body 1 and the screw rod has strong adaptability and is very convenient for installation and replacement.

[0064] The above is the specific structure of the reverse circulation anti-blocking drill bit of this embodiment. Due to the streamlined structural design of the first flow channel 110 and the second flow channel 120, the reverse circulation anti-blocking drill bit A is not easy to be blocked during operation, thereby effectively avoiding the occurrence of drill blockage, and can be widely used in reverse circulation drilling technology.

[0065] Based on the specific structure of the reverse circulation anti-blocking drill bit A, Figure 7 As shown, this embodiment also provides an air lift reverse circulation drilling system, including the above-mentioned reverse circulation anti-blocking drill bit A, an air compressor 2, a gas-liquid mixer 4, a double-wall drill pipe 5, a single-wall drill pipe 6 and a slag discharge pipe 7.

[0066] Among them, the double-wall drill pipe 5 is sleeved on the outer periphery of the single-wall drill pipe 6, the air compressor 2 is connected to the inner cavity of the double-wall drill pipe 5 through the air-water tap 3, the inner cavity of the double-wall drill pipe 5 is connected to the gas-liquid mixer 4, and the gas-liquid mixer 4 is connected to the inner cavity of the single-wall drill pipe 6. One end of the single-wall drill pipe 6 is connected to the reverse circulation anti-blocking drill bit, and the other end is connected to the slag discharge pipe 7, and the outlet of the slag discharge pipe 7 faces the sedimentation tank 8. The sedimentation tank 8 is also connected to the well 9, and the rock cuttings are directly discharged into the sedimentation tank 8 or collected after separation by the vibrating screen, and the flushing liquid after precipitation can be directly discharged into the well 9 for recycling.

[0067] Here, the working principle of the gas lift reverse circulation drilling system is to reduce the equivalent circulation density of the fluid in the drill pipe cavity by injecting gas, so that a pressure difference is generated inside and outside the drill pipe to make the fluid flow.

[0068] Specifically, the air compressor 2 sends the compressed air to the gas-liquid mixer 4 through the gas-water tap 3, the double-wall drill pipe 5, the single-wall drill pipe 6 and the annular gap of the double-wall drill pipe 5, and then the gas-liquid mixer 4 sprays it into the single-wall drill pipe 6, forming countless small bubbles, which rise rapidly along the single-wall drill pipe 6 and expand continuously, thereby generating a gas lift effect. As the compressed air continuously enters the drilling fluid 9 from the gas-liquid mixer 4, a gas-liquid mixed fluid with low specific gravity will be formed at the upper part of the gas-liquid mixer 4, while the specific gravity of the liquid outside the single-wall drill pipe 6 is greater than that of the gas-liquid mixed fluid. According to the principle of the communicating vessel, the gas-water mixed fluid in the single-wall drill pipe 6 flows upward under the action of the pressure difference, and at the same time, the rock cuttings at the bottom of the hole are continuously discharged into the sedimentation tank 8. The mud in the sedimentation tank 8 flows into the drilling well 9 again, and enters the single-wall drill pipe 6 through the reverse circulation anti-blocking drill bit A at the bottom of the well, and the continuous cycle forms a continuous drilling process.

[0069] In this embodiment, since the gas lift reverse circulation drilling system adopts the reverse circulation anti-blocking drill bit A, the reverse circulation anti-blocking drill bit A is not easy to be blocked during the continuous drilling process, thereby effectively avoiding the occurrence of drill blockage, thereby ensuring the drilling efficiency of the gas lift reverse circulation drilling system.

[0070] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which are all covered by the protection scope of the present invention.

Claims

1. A reverse circulation anti-blocking drill bit, characterized in that: include: A drill bit body, the upper end of which is used to connect with the drill rod; The first flow channel is streamlined and arranged at the center of the drill body. The first flow channel penetrates the drill body from top to bottom, and the size of the lower port is larger than the size of the upper port. A second flow channel is obliquely disposed in the drill body, and its axis intersects with the axis of the first flow channel; The upper port of the second flow channel is connected to the middle part of the first flow channel, and the lower port is located at the lower end of the drill body.

2. The reverse circulation anti-blocking drill bit according to claim 1, characterized in that: The inner diameter of the upper port of the first flow channel is consistent with the inner diameter of the drill rod, and the cross-sectional shape of the lower port is trumpet-shaped.

3. The reverse circulation anti-blocking drill bit according to claim 1, characterized in that: The lower end of the drill body is provided with at least three teeth, and the number of the second flow channels is at least three; At least three of the second flow channels are respectively located in the drill bit body between two adjacent tooth palms.

4. The reverse circulation anti-blocking drill bit according to claim 3, characterized in that: The diameter of the upper port of the second flow channel is greater than the diameter of the lower port of the second flow channel, and the area of ​​the water flow cross section of the upper port of the second flow channel is greater than or equal to the area of ​​the water flow cross section of the first flow channel.

5. The reverse circulation anti-blocking drill bit according to claim 4, characterized in that: The second flow channel comprises: A transition section, located at an upper end of the second flow channel and connected to the first flow channel; The guide section is located at the lower port of the second flow channel and is smoothly connected with the transition section. The guide section is cylindrical.

6. The reverse circulation anti-blocking drill bit according to claim 5, characterized in that: The cross-sectional shape of the transition section is bowl-shaped.

7. The reverse circulation anti-blocking drill bit according to claim 5, characterized in that: The cross-sectional shape of the transition section is trumpet-shaped.

8. The reverse circulation anti-blocking drill bit according to claim 5, characterized in that: The cross-sectional shape of the transition section is an inverted cone.

9. The reverse circulation anti-blocking drill bit according to claim 1, characterized in that: The outer ring of the first end of the drill bit body is provided with an external thread, and the drill bit body can be connected to the drill rod through the external thread.

10. A gas lift reverse circulation drilling system, characterized in that: A reverse circulation anti-blocking drill bit comprising the reverse circulation anti-blocking drill bit according to any one of claims 1 to 9.

Images