A slim hole horizontal well through-drilling tool and method of use

Abstract

This invention discloses a small-diameter horizontal well cleaning tool and its usage method, comprising the following steps: First, lowering the small-diameter horizontal well cleaning tool to the bottom of the well; second, starting the pump for circulation; third, pulling out the drill string, connecting the drill string to the wellhead via a continuous circulation device. During the drilling fluid circulation process, the drilling fluid returns from the rotary circulation sub, flushing the well wall, causing microbubbles attached to the well wall to move. As the bubbles move, they accumulate and thicken, forming microbubble clusters that detach from the well wall. These microbubble clusters enter the drilling fluid and move with it during circulation, eventually exiting the wellhead with the continuous circulation of the drilling fluid, and the microbubbles on the well wall disappear. Through the rotary circulation sub, while the cleaning tool is being lifted, the drilling fluid rotates and pulses to flush the well wall, causing microbubbles on the well wall to move and accumulate with other microbubbles to form large microbubble clusters, thus detaching from the well wall and entering the drilling fluid, ultimately being circulated out of the wellhead by the drilling fluid.

Description

Technical Field

[0001] This invention belongs to the field of drilling, specifically relating to a drilling tool for small-bore horizontal wells and its usage method. Background Technology

[0002] In small-diameter horizontal wells, the horizontal section is long. To protect the producing formation, the drilling fluid density is relatively low during drilling. After entering the producing formation through the wellbore inlet, natural gas inside the producing formation is prone to overflow. Most of this overflowing natural gas enters the drilling fluid and is circulated out of the wellhead. Some of the overflowing natural gas adheres to the well wall in the form of microbubbles. In the horizontal section, the natural gas adheres to the upper well wall in the form of microbubbles, and its adhesion is strong, which affects the quality of subsequent cementing. It is easy to cause annular cement ring grooves, resulting in poor volumetric fracturing effect, wasting a lot of money, and increasing the difficulty of subsequent modification.

[0003] Currently, the only measures that can be taken on-site are to repeatedly adjust the properties of the drilling fluid and continuously circulate the well. The aim is to completely circulate the natural gas microbubbles adhering to the well wall in the horizontal section to meet the requirements of cementing. However, the results are often unsatisfactory, and at the same time, a lot of manpower and resources are wasted, resulting in low efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a drilling tool and method for cleaning small-bore horizontal wells to solve the problem of microbubbles adhering to the well wall.

[0005] The objective of this invention is achieved through the following technical means:

[0006] A drilling tool for small-bore horizontal wells includes a drill pipe, and a centralizer and a rotary circulation sub connected sequentially from top to bottom to the drill pipe. A pressure control plug is connected to the bottom end of the drill pipe. The rotary circulation sub...

[0007] There are two centralizers, which are respectively connected to the upper and lower ends of the drill pipe of the rotary circulation sub.

[0008] The inner wall of the outer cylinder is connected to a fixing ring, and the upper end of the outer cylinder is connected to the fixing ring.

[0009] A bearing is connected to the lower end outlet of the outer cylinder, and a rotor section extends out from the bearing.

[0010] The rotor short section is located on the outer wall of the outer cylinder section and is also connected to the stator sleeve.

[0011] A method for using drilling tools for small-bore horizontal wells includes the following steps:

[0012] The first step is to lower the small-diameter horizontal well cleaning tool to the bottom of the well.

[0013] The second step is to start the pump for circulation. The pump is started at the wellhead, and the drilling fluid in the wellbore circulates to circulate most of the air bubbles to the wellhead for discharge. After circulating for a period of time, the pump is stopped.

[0014] The third step is tripping the drill string. The tripping continuous circulation device is connected to the wellhead. The tripping continuous circulation device drives the drilling tool of the small-diameter horizontal well to be pulled up while circulating the drilling fluid. During the circulation process, the drilling fluid returns from the radial flow nozzle of the rotary circulation sub, washing the well wall. This causes the microbubbles attached to the well wall to move. As the drill string moves up, the bubbles accumulate and thicken, turning into microbubble clusters that detach from the well wall. The microbubble clusters enter the drilling fluid and move with the drilling fluid circulation. Finally, they exit the wellhead with the continuous circulation of the drilling fluid, and the microbubbles on the well wall disappear.

[0015] In the second step, the drilling fluid is pulsed and flushed against the well wall at an angle of 30-45 degrees.

[0016] During the second step of tripping in, a ball is dropped from the wellhead to the pressure control plug of the horizontal wellbore drilling tool in the small wellbore for setting.

[0017] The beneficial effects of this invention are as follows: by using a rotary circulation sub, the drilling fluid rotates and pulses to flush the well wall while the drilling tool is being lifted, causing microbubbles on the well wall to move and accumulate with other microbubbles to form large microbubble clusters, thereby detaching from the well wall and entering the drilling fluid, and finally being circulated out of the wellhead by the drilling fluid, saving manpower and resources. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the drilling tool structure for a small-diameter horizontal well.

[0019] Figure 2 This is a schematic diagram of a rotary recirculating sub-section structure;

[0020] In the diagram: 1. Drill pipe; 2. Centralizer; 3. Rotary circulating sub; 4. Pressure control plug; 5. Drill pipe thread; 6. Fixing ring; 7. Outer cylinder; 8. Rotor sub; 9. Stator sleeve; 10. Bearing; 11. Radial fluid jet.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0022]

Example 1

[0023] like Figure 1 and Figure 2As shown, a small-bore horizontal well drilling tool includes a drill pipe 1, and a centralizer 2 and a rotary circulation sub 3 connected sequentially from top to bottom to the drill pipe 1. A pressure control plug 4 is connected to the bottom end of the drill pipe 1. The rotary circulation sub 3 includes an outer cylinder 7 and a rotor sub 8. Both the outer cylinder 7 and the rotor sub 8 are hollow structures. The upper end of the outer cylinder 7 is connected to the drill pipe 1, and the rotor sub 8 extends from the lower end of the outer cylinder 7. The rotor sub 8 is rotatably connected to the inner wall of the outer cylinder 7. The part of the rotor sub 8 extending out of the outer cylinder 7 is provided with a radial fluid flow nozzle 11. The rotor sub 8 below the radial fluid flow nozzle 11 is connected to the drill pipe 1.

[0024] There are two centralizers 2, which are respectively connected to the upper and lower ends of the drill rod 1 of the rotary circulation sub 3.

[0025] The inner wall of the outer cylinder 7 is connected to a fixing ring 6, and the upper end of the outer cylinder 7 is connected to the fixing ring 7.

[0026] A bearing 10 is connected to the lower end outlet of the outer cylinder 7, and the rotor stub 8 extends out from the bearing 10.

[0027] The rotor short section 8 is located on the outer wall of the outer cylinder 7 and is also connected to the stator sleeve 9.

[0028] like Figure 2 As shown, from top to bottom, the stabilizer 2, the rotary circulation sub 3, the stabilizer 2, and the pressure control plug 4 are connected to each other through the drill pipe 1.

[0029] The rotary circulating sub 3 includes an outer cylinder 7 and a rotor sub 8. The upper end of the outer cylinder 7 is provided with a drill rod thread 5 for connecting to the drill rod 1. The upper end of the rotor sub 8 is located inside the hollow of the outer cylinder 7, and the lower end of the rotor sub 8 extends out from the outlet at the lower end of the outer cylinder 7.

[0030] The upper end of the rotor short section 8 is located inside the outer cylinder 7, and the outer wall of the upper end of the rotor short section 8 is connected to the fixing ring 6, and the outer wall of the fixing ring 6 is connected to the inner wall of the outer cylinder 7.

[0031] The outer cylinder 7 is connected to the outlet at the lower end of the bearing 10. The rotor short section 8 extends out from the inner ring of the bearing 10. Under the combined action of the fixed ring 6 and the bearing 10, the rotor short section 8 can rotate inside the outer cylinder 7.

[0032] Furthermore, a stator sleeve 9 is connected to the outer wall of the rotor short section 8 inside the outer cylinder 7.

[0033] The portion of the rotor sub 8 extending beyond the outer cylinder 7 is equipped with radial fluid jets 11. These jets connect the hollow pipe inside the rotor sub 8 to the outside, allowing drilling fluid to return from the radial fluid jets 11. Different angles of the radial fluid jets 11 result in different angles at which the drilling fluid returns. Below the radial fluid jets 11, the rotor sub 8 is also equipped with drill pipe threads 5 for connection to the drill pipe 1. Multiple radial fluid jets 11 are provided.

[0034] During use, such as in the second step of pumping and circulation, the drilling fluid flows through the drill pipe 1, the rotor short section 8, and the hollow inside the outer cylinder 7 to the bottom of the well for circulation.

[0035] During the third step of tripping in, the drilling fluid enters the upper end of the rotor section 8 from the upper end of the outer cylinder 7, and then exits from the radial fluid jet 11 of the rotor section 8 to flush the microbubbles on the well wall. During the drilling fluid circulation process, the rotor section 8 is driven to rotate, which changes the ejection position of the radial fluid jet 11, thereby flushing the well wall in all directions.

[0036]

Example 2

[0037] A method for using drilling tools for small-bore horizontal wells includes the following steps:

[0038] The first step is to lower the small-diameter horizontal well cleaning tool to the bottom of the well.

[0039] The second step is to start the pump for circulation. The pump is started at the wellhead, and the drilling fluid in the wellbore circulates to circulate most of the air bubbles to the wellhead for discharge. After circulating for a period of time, the pump is stopped.

[0040] The third step is tripping the drill string. The tripping continuous circulation device is connected to the wellhead. The tripping continuous circulation device drives the drilling tool of the small-diameter horizontal well to be pulled up while circulating the drilling fluid. During the circulation of the drilling fluid, it returns from the radial fluid jet 11 of the rotary circulation sub 4, flushing the well wall. This causes the microbubbles attached to the well wall to move. As the drill string moves up, the bubbles accumulate and thicken, turning into microbubble clusters that detach from the well wall. The microbubble clusters enter the drilling fluid and move with the drilling fluid circulation. Finally, they exit the wellhead with the continuous circulation of the drilling fluid, and the microbubbles on the well wall disappear.

[0041] In the second step, the drilling fluid is pulsed and flushed against the well wall at an angle of 30-45 degrees.

[0042] During the second step of tripping in, a ball is dropped from the wellhead to the pressure control plug 4 of the horizontal wellbore drilling tool for setting.

[0043] When in use, first lower the small-diameter horizontal well cleaning tool to the bottom of the well to prepare for circulation; during the lowering process, the centralizer 2 also serves to clean the well and scrape the cuttings off the well wall.

[0044] Then, the pump is turned on at the wellhead to input drilling fluid into the well through drill pipe 1 and circulate it. Most of the gas is circulated to the wellhead with the drilling fluid and discharged, but some microbubbles will still adhere to the well wall.

[0045] Then the pump is stopped, the ball is dropped and set, the equipment is lifted, and the drilling fluid circulation device is connected to the wellhead to achieve the process of lifting the drilling tools for the small-diameter horizontal well while continuing to inject drilling fluid into the well for circulation.

[0046] The aforementioned continuous circulation device for tripping drill fluid is an existing device that can circulate drilling fluid while tripping drill fluid.

[0047] From the moment the ball is dropped into the wellhead until the pressure control plug 4 is set, the drilling fluid can only exit through the rotary circulation sub 4. During the hoisting process, the drilling fluid circulates within the drill string. As the drilling fluid flows through the rotary circulation sub 4, it drives the sub to rotate, causing the fluid to flow back out. This pulses the drilling fluid at a 30-45 degree angle, causing the natural gas microbubbles adhering to the wellbore to move. Wellhead drilling fluid injection rate: 16-18 L / s; Rotation speed of the rotary circulation sub 4: 60-80 rpm.

[0048] As the drill string is pulled up further, the microbubbles that are washed down also move upwards, accumulating with the microbubbles above to form large microbubble clusters. These microbubble clusters detach from the well wall and enter the drilling fluid, and are then discharged from the wellhead as the drilling fluid circulates.

[0049] Some of the microbubbles will adhere to the well wall above after they move. As the drill string is pulled up, the microbubbles are continuously washed away, forming new microbubble clusters. This continuously washes away the microbubbles on the well wall. The washed-away microbubble clusters are pushed to form larger microbubble clusters, which detach from the well wall and enter the drilling fluid. They then circulate out of the wellhead with the drilling fluid, eventually circulating all the microbubbles on the well wall out of the wellhead.

[0050] This prevents the cement from affecting the bonding between the cement and the formation during cementing, ensuring the quality of subsequent cementing. It eliminates the need to adjust drilling fluid properties or repeatedly circulate the well.

Claims

1. A drilling tool for cleaning small-bore horizontal wells, characterized in that: The system includes a drill rod (1), a stabilizer (2) and a rotary circulation sub (3) connected sequentially from top to bottom to the drill rod (1). The bottom end of the drill rod (1) is connected to a pressure control plug (4). The rotary circulation sub (3) includes an outer cylinder (7) and a rotor sub (8). Both the outer cylinder (7) and the rotor sub (8) are hollow structures. The upper end of the outer cylinder (7) is connected to the drill rod (1). The rotor sub (8) extends from the lower end of the outer cylinder (7) and is rotatably connected to the inner wall of the outer cylinder (7). The part of the rotor sub (8) extending out of the outer cylinder (7) is provided with a radial liquid flow nozzle (11). The rotor sub (8) below the radial liquid flow nozzle (11) is connected to the drill rod (1). The inner wall of the outer cylinder (7) is connected to a fixing ring (6), and the upper end of the outer cylinder (7) is connected to the fixing ring (6); The outer cylinder (7) is connected to a bearing (10) at its lower outlet, and the rotor short section (8) extends out from the bearing (10); The rotor short section (8) is located on the outer wall of the outer cylinder (7) and is also connected to the stator sleeve (9).

2. The drilling tool for cleaning small-bore horizontal wells according to claim 1, characterized in that: There are two centralizers (2), which are connected to the upper and lower ends of the drill rod (1) of the rotary circulation sub (3) respectively.

3. The method of using a drilling tool for cleaning small-bore horizontal wells according to any one of claims 1-2, characterized in that, Includes the following steps: The first step is to lower the small-diameter horizontal well cleaning tool to the bottom of the well. The second step is to start the pump for circulation. The pump is started at the wellhead, and the drilling fluid in the wellbore circulates to circulate most of the air bubbles to the wellhead for discharge. After circulating for a period of time, the pump is stopped. The third step is to pull out the drill string. The drill string is connected to the continuous circulation device at the wellhead. The continuous circulation device drives the drilling fluid of the small-diameter horizontal well to be pulled up while circulating. During the circulation of the drilling fluid, it returns from the radial flow nozzle (11) of the rotary circulation sub and washes the well wall, causing the microbubbles attached to the well wall to move. As the drill string moves up, the bubbles accumulate and thicken, becoming microbubble clusters that detach from the well wall. The microbubble clusters enter the drilling fluid and move with the drilling fluid circulation. Finally, they exit the wellhead with the continuous circulation of the drilling fluid, and the microbubbles on the well wall disappear.

4. The method for using a drilling tool for cleaning small-bore horizontal wells according to claim 3, characterized in that: In the second step, the drilling fluid is pulsed and flushed against the well wall at an angle of 30-45 degrees.

5. The method for using a drilling tool for cleaning small-bore horizontal wells according to claim 3, characterized in that: During the second step of tripping, a ball is dropped from the wellhead to the pressure control plug (4) of the horizontal wellbore drilling tool for setting.

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