Ball valve type downhole drilling plugging device and use method

Abstract

A ball valve-type downhole plugging device and its usage method belong to the field of blowout preventer (BOP) technology. The device includes a central tube, an upper connector, a centralizer, a lower connector, a plugging mechanism, and a ball-dropping mechanism. The plugging mechanism is connected to the inner wall of the central tube via three sets of shear pins. The three sets of shear pins, from top to bottom, include an upper shear pin, a middle shear pin, and a lower shear pin. An expansion sleeve is also provided on the outer wall of the central tube on one side of the lower part of the plugging mechanism. Each set of shear pins is equipped with a stroke limiting groove. The three sets of stroke limiting grooves and the corresponding shear pins limit the position of the plugging mechanism during operation. The method includes running it into the well, setting the plug, allowing drilling fluid to circulate internally and externally, and then unsealing it. This invention can achieve both setting and unsealing operations at the bottom of the well, simultaneously sealing the inside of the drill pipe and the annulus between the drill pipe and the casing / open hole.

Description

Technical Field

[0001] This invention belongs to the field of blowout preventer technology, specifically relating to a ball valve type downhole plugging device and its usage method. Background Technology

[0002] Offshore oil and gas development is characterized by high investment and high risk. According to statistics from WOAD and SINTEF databases, 60% of major accidents such as well blowouts and explosions in offshore oil wells occur before drilling is completed. Therefore, preventing well blowouts during drilling is of great significance to ensuring the safety of offshore drilling.

[0003] During drilling, a check valve is typically installed near the drill bit to prevent backflow of fluid within the drill string, thus addressing blowout prevention within the drill string. However, blowout prevention in the annulus between the casing and drill pipe is controlled by a platform wellhead blowout preventer. The blowout preventer is usually installed on the casing head at the wellhead and seals the wellhead when the oil and gas pressure inside the well is high. When heavy mud is injected into the drill pipe, a four-way valve below the gate replaces the gas-infiltrated mud, increasing the pressure of the fluid column inside the well to suppress the ejection of high-pressure oil and gas.

[0004] However, existing blowout preventers are used to prevent oil and gas splashing at the wellhead, but pressure accumulates at the wellhead. Once the pressure gets out of control, it will cause a serious blowout accident and threaten the safety of wellhead workers. Summary of the Invention

[0005] This invention discloses a ball valve type downhole sealing device and its usage method. When high-pressure overflow enters the annulus outside the drill pipe and causes a well kick, this invention can provide emergency blowout prevention below the mud surface and seal the annulus between the outer wall of the drill pipe and the inner wall of the casing, preventing high-pressure oil and gas from moving upward. This can greatly reduce the risk of uncontrolled oil and gas splashing at the wellhead and buy valuable time for emergency response on the platform.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A ball valve type downhole plugging device includes a central tube, an upper connector, a centralizer, a lower connector, a plugging mechanism, and a ball-throwing mechanism. The upper end of the central tube is connected to the upper connector, and the lower end is connected to the lower connector via the centralizer. The plugging mechanism is installed inside the central tube, and the ball-throwing mechanism is installed on the inner wall of the central tube above the plugging mechanism. The ball-throwing mechanism works in conjunction with the plugging mechanism. The plugging mechanism is connected to the inner wall of the central tube by three sets of shear pins, which, from top to bottom, include an upper shear pin, a middle shear pin, and a lower shear pin. An expansion sleeve is also provided on the outer wall of the central tube on one side of the lower part of the plugging mechanism. The plugging mechanism works in conjunction with the expansion sleeve. Each set of shear pins is equipped with a stroke limiting groove. The three sets of stroke limiting grooves and the corresponding shear pins limit the position of the plugging mechanism during operation. The three positions from top to bottom correspond to the setting state, the drilling fluid internal and external flow state, and the unsealing state, respectively.

[0008] Preferably, the sealing mechanism includes a ball valve body, a ball valve seat, an upper drainage hole, a middle drainage hole, and a lower drainage hole. The ball valve body is a cylindrical hollow shell structure. A central channel connecting the upper and lower ends of the ball valve body is formed by welding a vertical pipe at the central axis of the ball valve body. There are multiple upper drainage holes, middle drainage holes, and lower drainage holes. Multiple upper drainage holes, middle drainage holes, or lower drainage holes are opened on the outer wall of the ball valve body and are evenly distributed around the axis of the ball valve body. There are also multiple radially arranged through holes evenly distributed around the axis on the ball valve body between the middle drainage hole and the lower drainage hole. The through hole is formed by a welded transverse pipe, one end of which passes through the central channel and the other end of which passes through the outer surface of the ball valve body. The outer wall of the ball valve body is connected to the inner surface of the central pipe by a cylindrical ball valve seat. The upper inner surface of the ball valve seat has an annular space around its axis. The inner wall of the ball valve seat, where the lower edge of the annular space is located, has multiple evenly distributed upper shear pins along the radial direction. The ends of the upper shear pins extend inward and enter the first stroke limiting groove formed on the outer wall of the ball valve body and arranged axially. Below the upper shear pins... The inner wall of the ball valve seat has multiple evenly distributed channels that connect the inside and outside of the ball valve seat. A first outlet hole is provided on the wall of the central tube corresponding to channel one. Multiple evenly distributed, radially arranged intermediate shear pins are installed on the inner wall of the ball valve seat below channel one. The heads of the intermediate shear pins extend inward and enter a second stroke limiting groove formed on the outer wall of the ball valve body along the axial direction. Multiple evenly distributed, penetrating channels two are provided on the side wall of the ball valve seat below the intermediate shear pins. The outer wall of the central tube opposite channel two... The ball valve body is provided with a second liquid outlet. Multiple evenly distributed and radially arranged lower shear pins are installed on the inner wall of the ball valve seat below the second channel. The heads of the lower shear pins extend inward and enter the third stroke limiting groove opened on the outer wall of the ball valve body and arranged axially. The bottom end of the ball valve seat is folded inward to form an annular limiting plate. The annular limiting plate is used to limit the lowest position of the ball valve body. The inner diameter of the first channel is smaller than the inner diameter of the second channel. The heights of the first stroke limiting groove, the second stroke limiting groove, and the third stroke limiting groove increase sequentially.

[0009] In the initial state, the ball valve body is positioned by the upper shear pin, channel one and channel two are blocked by the ball valve body, the through hole is blocked by the inner wall of the ball valve seat, and the annular space is in a closed state.

[0010] In the set-sealed state, the upper shear pin is sheared, the ball valve body moves downward along the axis and is positioned by the middle shear pin. At this time, the lower drain hole is opposite to the second channel, and the first channel continues to be blocked by the ball valve body, the through hole continues to be blocked by the ball valve seat, the upper end of the annular space is opened, and the upper drain hole is opposite to the annular space.

[0011] When the drilling fluid is flowing inside and outside, the middle shear pin is sheared, the ball valve body moves down along the axis and is positioned by the lower shear pin. At this time, the lower drainage hole is still opposite to channel two, the middle drainage hole is opposite to channel one, the through hole continues to be blocked by the ball valve seat, the upper end of the annular space remains open, and the upper drainage hole continues to be opposite to the annular space.

[0012] In the unsealed state, the lower shear pin is sheared, the bottom of the ball valve body abuts against the annular limiting plate, the lower drain hole and the through hole are both opposite to channel two, channel one is blocked by the ball valve body, the upper end of the annular space remains open, the upper drain hole continues to be opposite to the annular space, and the middle drain hole is blocked by the ball valve seat.

[0013] The inner wall of the expansion tube is opposite to the outer wall of the central tube, and an annular groove is formed around the axis. The second liquid outlet hole passes through the bottom of the annular groove and is opposite to the inner wall of the expansion tube. The inner surface of the expansion tube located on the upper and lower sides of the annular groove is sealed and fixedly connected to the outer surface of the central tube.

[0014] Preferably, the throwing mechanism includes a horizontal tube, an arc-shaped tube, a compression spring, a piston, and a steel ball. One end of the horizontal tube is closed, and the open end is screwed to a threaded hole on the outer wall of the central tube. The piston is slidably connected inside the horizontal tube. A compression spring is connected between the inner end of the piston and the inner surface of the sealed end of the horizontal tube. A limiting groove is formed at the lower end of the piston, and the steel ball is placed in the limiting groove. A limiting rod is also provided between the piston and the closed end. One end of the limiting rod is fixedly connected to the inner surface of the closed end, and the other end extends along the axial direction of the horizontal tube to the piston side. The limiting rod is used to limit the maximum distance the piston moves inward. An arc-shaped tube inclined towards the inner side of the central tube is connected to the lower end of the horizontal tube. The upper port and inner diameter of the arc-shaped tube are adapted to the size of the steel ball. In the initial state, the compression spring compresses the piston, and the piston closes the horizontal tube. When subjected to a certain pressure, the compression spring contracts, the lower port of the limiting groove aligns with the upper port of the arc-shaped tube, and the steel ball is thrown out along the arc-shaped tube.

[0015] Preferably, in the initial state, the top ends of the ball valve body and the ball valve seat form a continuous spherical groove, which is used to guide the steel ball to the top end of the central channel and block the central channel. The top end of the ball valve body and the upper port surrounding the central channel are provided with an annular magnet block for strongly adsorbing and positioning the steel ball.

[0016] Preferably, a pressure sensor is installed at the connection point between the drill string tip and the drilling equipment. In the event of downhole overflow or well kick, the abnormal data detected by the pressure sensor is used to determine the occurrence of downhole overflow or well kick.

[0017] A method for using a ball valve type downhole plugging device includes the following steps:

[0018] Step 1: Running into the well while drilling:

[0019] The ball valve type downhole plugging device is part of the downhole drill string and is lowered into the well along with the drill string during drilling. During normal drilling, the drilling fluid flows through the central channel of the ball valve body. The plugging device uses a stabilizer to prevent the plugging device from wearing out and damaging the expansion sleeve, thus preventing the plugging device from being scrapped prematurely.

[0020] Step 2, Sealing Process:

[0021] When encountering downhole overflow or well kick, high-pressure fluid rushes into the annulus outside the drill string. When the pressure in the annulus increases to a certain value, the piston moves inward to its maximum stroke. At this time, the steel ball falls and is thrown out along the arc-shaped tube, blocking the upper port of the central channel of the ball valve body. At this time, the drilling fluid in the drill string cannot flow into the central channel. When the drilling fluid is pressurized, the first stroke limit groove shears the upper shear pin, and the ball valve body moves downward. Under the resistance of the middle shear pin, it is repositioned. At this time, the top of the ball valve body and the ball valve seat are offset, and the top of the annular space is open. The drilling fluid in the drill string enters the ball valve body through the upper drainage hole. At this time, the middle drainage hole on the ball valve body and channels one and two are blocked, while the lower drainage hole is connected to channel two. The drilling fluid enters the annular groove through the lower drainage hole, channel two, and the second outlet hole, and squeezes the expansion sleeve to expand, so that the expansion sleeve and the casing in the well are tightly pressed together, thereby sealing the annulus between the casing and the drill string. At this time, the setting seal is achieved.

[0022] Step 3: Internal and external circulation process of drilling fluid:

[0023] When the pressure sensor detects abnormal data, the pressure of the drilling fluid in the drill string is increased. The pressure is increased by increasing the density of the drilling fluid in the input drill string, which increases the pressure of the drilling fluid column above the ball valve body. This causes the middle shear pin to be sheared by the second stroke limiting groove, and the ball valve body moves downward. The lower shear pin moves upward along the third stroke limiting groove and positions the ball valve body. At this time, the middle drainage hole is connected to channel one, and the lower drainage hole is still connected to channel two. The drilling fluid enters the ball valve body from the upper drainage hole. Part of the drilling fluid flows out through channel two to maintain the setting state, and the other part of the drilling fluid flows out through the middle drainage hole, channel one, and the first outlet hole. The outflowing drilling fluid flows into the annulus between the drill string and the casing above the expansion sleeve to form the kill fluid in the annulus. This forms the circulation of drilling fluid inside and outside the drill string. As the height of the kill fluid in the annulus increases, the sealing force against well kick or overflow of drilling fluid in the annulus below the expansion sleeve is further enhanced.

[0024] Step 4: Unsealing process:

[0025] When high-density drilling fluid is injected into the wellhead for well control, the pressure of the liquid column above the ball valve body continues to increase. According to daily experimental data, the pressure of the liquid column above the ball valve body is made greater than the pressure of the high-pressure fluid below. At this time, the lower shear pin is sheared by the third stroke limiting groove, and the bottom end of the ball valve body abuts against the annular limiting plate. At this time, the drilling fluid enters the ball valve body from the upper drainage hole, while the middle drainage hole is blocked by the ball valve seat. The lower drainage hole is connected to channel two. At the same time, the through hole is also connected to channel two. The drilling fluid in channel two and the annular groove enters the drill string below the sealing mechanism through the through hole and the central channel. At this time, the drilling fluid in the drill string resumes the downward output state, the expansion sleeve contracts, and the device and casing are unsealed.

[0026] The beneficial effects of the ball valve type downhole plugging device and its usage method of the present invention are as follows:

[0027] This invention enables both setting and unsealing operations at the bottom of the well, simultaneously sealing the inside of the drill pipe and the annulus between the drill pipe and the casing / open hole. Unlike surface ball-dropping, this invention places the ball-dropping device at the bottom of the well, significantly reducing response time and preventing well kicks and high-pressure overflows from escalating into blowouts.

[0028] Instruction manual illustrations

[0029] Figure 1 A schematic diagram of the overall structure of the present invention.

[0030] Figure 2 A partial structural diagram of point A in this invention.

[0031] Figure 3 A schematic diagram of the ball-throwing mechanism of the present invention in its initial state.

[0032] Figure 4 A schematic diagram of the ball-throwing mechanism of the present invention in the ball-throwing state.

[0033] Figure 5 A schematic diagram of the sealing mechanism of the present invention in the setting state.

[0034] Figure 6 A schematic diagram showing the flow of drilling fluid inside and outside the well after sealing in this invention.

[0035] Figure 7 A schematic diagram illustrating the unsealing process during well control in the application of this invention.

[0036] Figure 8 A cross-sectional view of the central tube of the present invention having an annular groove.

[0037] Figure 9 A schematic diagram of the shear pin and the first stroke limiting groove of the present invention.

[0038] Figure 10A schematic diagram of the cooperation between the shear pin and the second stroke limiting groove in this invention.

[0039] Figure 11 A schematic diagram of the cooperation between the shear pin and the third stroke limiting groove of the present invention.

[0040] 1. Upper connector; 2. Ball dropping mechanism; 201. Horizontal tube; 202. Compression spring; 203. Arc-shaped tube; 204. Piston; 205. Limiting groove; 206. Steel ball; 207. Open end; 208. Limiting rod; 3. Ball valve body; 301. Outer wall of ball valve body; 4. Ball valve seat; 401. Outer wall of ball valve seat; 5. Upper drain hole; 6. Middle drain hole; 7. Lower drain hole; 8. Upper shear pin; 9. Middle shear pin; 10. Lower shear pin 11. Disconnect pin; 12. Through hole; 13. Channel 2; 14. Expansion sleeve; 15. Central channel; 16. Central tube; 1601. Outer wall of central tube; 1602. Threaded hole; 1603. Second liquid outlet; 1604. Annular groove; 17. Centralizer; 18. Second stroke limit groove; 19. First stroke limit groove; 20. Third stroke limit groove; 21. Sleeve; 22. Lower connector; 23. Annular space. Detailed Implementation

[0041] The following description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0042] Example 1

[0043] A ball valve type downhole plugging device, such as Figure 1-11 As shown, the plugging device constitutes a short joint structure of the oil well drill string, including a central pipe 16, an upper joint 1, a centralizer 17, a lower joint, a plugging mechanism, and a ball-throwing mechanism. The upper end of the central pipe is connected to the upper joint 1, and the lower end is connected to the lower joint through the centralizer 17. The plugging mechanism is installed inside the central pipe, and the ball-throwing mechanism is installed on the inner wall of the central pipe above the plugging mechanism. The ball-throwing mechanism works in conjunction with the plugging mechanism. The plugging mechanism is connected to the inner wall of the central pipe through three sets of shear pins. The three sets of shear pins, from top to bottom, include an upper shear pin 8, a middle shear pin 9, and a lower shear pin 10. An expansion sleeve 14 is also provided on the outer wall of the central pipe on one side of the lower part of the plugging mechanism. The plugging mechanism works in conjunction with the expansion sleeve. Each set of shear pins is equipped with a stroke limiting groove. The three sets of stroke limiting grooves and the corresponding shear pins limit the position of the plugging mechanism during operation. The three positions from top to bottom correspond to the setting state, the drilling fluid internal and external flow state, and the unsealing state, respectively.

[0044] Example 2

[0045] Based on Example 1, this example discloses:

[0046] like Figure 1-11 As shown, the sealing mechanism includes a ball valve body 3, a ball valve seat 4, an upper drainage hole 5, a middle drainage hole 6, and a lower drainage hole 7. The ball valve body 3 is a cylindrical hollow shell structure. A central channel 15, which runs through the upper and lower ends of the ball valve body, is formed by welding a vertical pipe at the central axis of the ball valve body 3. There are multiple upper drainage holes 5, middle drainage holes 6, and lower drainage holes 7. These multiple upper drainage holes 5, middle drainage holes 6, or lower drainage holes 7 are opened on the outer wall of the ball valve body and are evenly distributed around the axis of the ball valve body. Multiple radially arranged through holes 12 are also evenly distributed around the axis on the ball valve body between the middle drainage hole and the lower drainage hole. The valve body 3 is constructed from welded transverse pipes, one end of which passes through a central channel and the other end of which passes through the outer surface of the ball valve body 3. The outer wall of the ball valve body 3 is connected to the inner surface of the central pipe 16 via a cylindrical ball valve seat 4. An annular space 23 is provided around the axis on the upper inner surface of the ball valve seat 4. Multiple evenly distributed upper shear pins 8 are provided radially on the inner wall of the ball valve seat 4 where the lower edge of the annular space 23 is located. The ends of the upper shear pins 8 extend inward and enter a first stroke limiting groove 19 formed on the outer wall of the ball valve body 3 and arranged axially. Multiple... A first channel 11, evenly distributed and penetrating the inside and outside of the ball valve seat 4, has a first liquid outlet hole (not marked in the figure) on the wall of the central tube corresponding to the first channel 11. Multiple evenly distributed and radially arranged intermediate shear pins 9 are installed on the inner wall of the ball valve seat 4 below the first channel 11. The heads of the intermediate shear pins 9 extend inward and enter the second stroke limiting groove 18, which is axially arranged on the outer wall of the ball valve body 3. Multiple evenly distributed and penetrating channels 13, corresponding to the second channel 13, are opened on the side wall of the ball valve seat below the intermediate shear pins 9. A second liquid outlet hole 1 is provided on the outer wall of the central tube 16 opposite to the channels 13. 603, multiple evenly distributed and radially arranged lower shear pins 10 are installed on the inner wall of the ball valve seat 4 below the second channel 13. The head of the lower shear pin 10 extends inward and enters the third stroke limiting groove 20 opened on the outer wall of the ball valve body 3 and arranged axially. The bottom end of the ball valve seat 4 is folded inward to form an annular limiting plate (not marked in the figure). The annular limiting plate is used to limit the lowest position of the ball valve body 3. The inner diameter of the first channel 11 is smaller than the inner diameter of the second channel 13. The heights of the first stroke limiting groove 19, the second stroke limiting groove 18, and the third stroke limiting groove 20 increase sequentially.

[0047] In the initial state, the ball valve body 3 is positioned by the upper shear pin 8, the first channel 11 and the second channel 13 are blocked by the ball valve body 3, the through hole 12 is blocked by the inner wall of the ball valve seat 4, and the annular space 23 is in a closed state.

[0048] In the set-sealed state, the upper shear pin 8 is sheared, the ball valve body 3 moves downward along the axis and is positioned by the middle shear pin 9. At this time, the lower drain hole 7 is opposite to the second channel 13, and the first channel 11 continues to be blocked by the ball valve body, the through hole 12 continues to be blocked by the ball valve seat 4, the upper end 23 of the annular space is opened, and the upper drain hole is opposite to the annular space.

[0049] When the drilling fluid is circulating inside and outside, the middle shear pin 9 is sheared, the ball valve body 3 moves down along the axis and is positioned by the lower shear pin 10. At this time, the lower drainage hole 7 is still opposite to the second channel 13, the middle drainage hole 6 is opposite to the first channel 11, the through hole 12 continues to be blocked by the ball valve seat 4, the upper end of the annular space 23 remains open, and the upper drainage hole continues to be opposite to the annular space.

[0050] In the unsealed state, the lower shear pin 10 is sheared, the bottom end of the ball valve body 3 abuts against the annular limiting plate, the lower drain hole 7 and the through hole 12 are both opposite to the second channel 13, the first channel 11 is blocked by the ball valve body 3, the upper end of the annular space remains open, the upper drain hole continues to be opposite to the annular space, and the middle drain hole is blocked by the ball valve seat.

[0051] Example 3

[0052] Based on Example 2, this example discloses:

[0053] like Figure 1-11 As shown, an annular groove 1604 is formed around the axis on the outer wall of the central tube 16 opposite to the inner wall of the expansion tube 14. The second liquid outlet 1603 passes through the bottom of the annular groove 1604 and is opposite to the inner wall of the expansion tube 14. The inner surface of the expansion tube 14 located on the upper and lower sides of the annular groove 1604 is sealed and fixedly connected to the outer surface of the central tube 16.

[0054] Example 4

[0055] Based on Example 3, this example discloses:

[0056] like Figure 1-4As shown, the throwing mechanism includes a horizontal tube 201, an arc-shaped tube 203, a compression spring 202, a piston 204, and a steel ball 206. One end of the horizontal tube 201 is closed, and the open end is screwed to a threaded hole 1602 on the outer wall 1601 of the central tube. The piston 204 is slidably connected inside the horizontal tube 201. A compression spring 202 is connected between the inner end of the piston 204 and the inner surface of the sealed end of the horizontal tube 201. A limiting groove 205 is formed at the lower end of the piston 204, and the steel ball 206 is placed in the limiting groove 205. A limiting rod 208 is also provided between the piston 204 and the closed end. One end of 08 is fixedly connected to the inner surface of the closed end, and the other end extends along the axial direction of the horizontal tube 201 to the side of the piston 204. The limiting rod 208 is used to limit the maximum distance that the piston 204 moves inward. The lower end of the horizontal tube 201 is connected to an arc-shaped tube 203 that is inclined towards the inner side of the central tube 16. The upper port and inner diameter of the arc-shaped tube 203 are adapted to the size of the steel ball 206. In the initial state, the compression spring 202 squeezes the piston, and the piston closes the horizontal tube 201. When subjected to a certain pressure, the compression spring 202 contracts, the lower port of the limiting groove aligns with the upper port of the arc-shaped tube 203, and the steel ball 206 is thrown out along the arc-shaped tube.

[0057] In this embodiment, when a well kick or overflow occurs, the high pressure of the fluid causes the piston to move inward. When the steel ball reaches the upper end of the arc-shaped tube, it falls and is ejected along the guide of the arc-shaped tube, thus sealing the central channel. When the well kick or overflow ends, the compression spring pushes the piston back to its original position, continuing to seal the horizontal tube. This design ensures the ball ejection function while preventing impurities from the external annulus from entering the central channel, thus avoiding blockage.

[0058] Example 5

[0059] Based on Example 4, this example discloses:

[0060] like Figure 1 , 2 As shown, in the initial state, the top ends of the ball valve body 3 and the ball valve seat 4 form a continuous spherical groove (not marked in the figure). The spherical groove is used to guide the steel ball to the top end of the central channel 15. The top end of the ball valve body 3 and the upper port of the central channel 15 are provided with an annular magnet block (not shown in the figure, to avoid the effect of the steel ball shaking on the sealing) for strongly adsorbing and positioning the steel ball.

[0061] Example 6

[0062] Based on Embodiment 5, this embodiment discloses that a pressure sensor (not shown in the figure) is installed at the connection point between the drill string tip and the drilling equipment. In the event of downhole overflow or well kick, abnormal data detected by the pressure sensor is used to determine the occurrence of downhole overflow or well kick. This determination point provides a reference for adding high-density drilling fluid into the drill string.

[0063] Example 7

[0064] Based on the above embodiments, this embodiment discloses a method for using a ball valve type downhole plugging device, such as... Figure 1-11 As shown, it includes the following steps:

[0065] Step 1: Running into the well while drilling:

[0066] This device is part of the downhole drill string and is lowered into the well along with the drill string during drilling. During normal drilling, the drilling fluid flows through the central channel of the ball valve body. The sealing device uses a stabilizer to prevent the sealing device from wearing out and damaging the expansion sleeve, thus preventing the sealing device from being scrapped prematurely.

[0067] Step 2, Sealing Process:

[0068] When encountering downhole overflow or kick, high-pressure fluid rushes into the annulus outside the drill string. When the pressure between the annulus increases to a certain value, the piston moves inward to its maximum stroke. At this time, the steel ball falls and is ejected along the arc-shaped tube, blocking the upper port of the central channel of the ball valve body. At this point, the drilling fluid in the drill string cannot flow into the central channel 15. When the drilling fluid is pressurized, the first stroke limit groove shears off the upper shear pin 6, and the ball valve body moves downward. It is then repositioned under the resistance of the middle shear pin 9. At this time, the top of the ball valve body and the ball valve seat are misaligned, and the annulus... The top of the shaped space is open, and the drilling fluid in the drill string enters the ball valve body through the upper drainage hole 5. At this time, the middle drainage hole 6, as well as channels one and two on the ball valve body are blocked, while the lower drainage hole 7 is connected to channel two 13. The drilling fluid enters the annular groove 1604 through the lower drainage hole 7, channel two 13, and the second outlet hole 1603, and is squeezed to expand the expansion rubber sleeve 14, so that the expansion rubber sleeve and the casing 21 in the well are tightly pressed together, thereby sealing the annulus between the casing and the drill string. At this time, the setting seal is achieved.

[0069] Step 3: Internal and external circulation process of drilling fluid:

[0070] Due to the lifting effect of the drilling fluid below the sealing mechanism on the expansion sleeve at the sealing position, when the pressure sensor detects abnormal data (the magnitude of this data can also be obtained through simulation experiments or experience data accumulation from daily drilling operations), the pressure of the drilling fluid in the drill string is increased. This is achieved by increasing the density of the drilling fluid input to the drill string, thus increasing the pressure of the drilling fluid column above the ball valve body. This causes the middle shear pin to be sheared by the second stroke limiting groove, causing the ball valve body to descend. The lower shear pin moves upward along the third stroke limiting groove and positions the ball valve body. At this time, the middle drainage hole 6 and channel one... 11 is connected, and the lower drainage hole 7 is still connected to channel 2 13. Drilling fluid enters the ball valve body 3 from the upper drainage hole 5. Part of the drilling fluid flows out through channel 2 to maintain the setting state, and the other part of the drilling fluid flows out through the middle drainage hole, channel 1 and the first outlet hole. The drilling fluid flowing out from the first outlet hole flows into the annulus between the drill string and the casing above the expansion sleeve to form the kill fluid in the annulus. This forms the circulation of drilling fluid inside and outside the drill string. As the height of the kill fluid in the annulus increases, the sealing force against well kick or overflow of drilling fluid in the annulus below the expansion sleeve is further enhanced.

[0071] Step 4: Unsealing process:

[0072] When high-density drilling fluid continues to be injected into the wellhead for well control (i.e., the process in step three), the pressure of the liquid column above the ball valve body continues to increase. According to daily experimental data, the pressure of the liquid column above the ball valve body is greater than the pressure of the high-pressure fluid below. At this time, the lower shear pin 10 is sheared by the third stroke limiting groove 20, and the bottom end of the ball valve body 3 abuts against the annular limiting plate. At this time, the drilling fluid enters the ball valve body from the upper drainage hole 5, while the middle drainage hole 6 is blocked by the ball valve seat 4. The lower drainage hole 7 is connected to the second channel 13. At the same time, the through hole 12 is also connected to the second channel. The drilling fluid in the second channel and the annular groove enters the drill string below the sealing mechanism through the through hole 12 and the central channel 15. At this time, the drilling fluid in the drill string resumes the downward output state, the expansion sleeve contracts, and the device and casing are unsealed.

[0073] It should be noted that the dimensions, strength, and related data of the relevant structures of the present invention during use can all be obtained through simulation experiments or field experimental data accumulation. For example, the strength data of the shear pin, the height data of the stroke limiting groove, the position data of each drainage hole, the pressure data provided by the kill fluid, and the pressure data of the high-pressure fluid in the well at different depths during the overflow or well kick are all included here. The detailed process of obtaining the above data will not be elaborated in the present invention.

[0074] This invention, through the aforementioned configuration, enables both setting and unsealing operations at the bottom of the well, simultaneously sealing the inside of the drill pipe and the annulus between the drill pipe and the casing / open hole. Unlike surface ball-dropping, this invention places the ball-dropping device at the bottom of the well, significantly reducing response time and preventing well kicks and high-pressure overflows from further evolving into blowouts.

Claims

1. A ball valve type downhole plugging device, characterized in that: The system includes a central tube, an upper connector, a centralizer, a lower connector, a plugging mechanism, and a ball-throwing mechanism. The upper end of the central tube is connected to the upper connector, and the lower end is connected to the lower connector via the centralizer. A plugging mechanism is installed inside the central tube, and a ball-throwing mechanism is installed on the inner wall of the central tube above the plugging mechanism. The ball-throwing mechanism works in conjunction with the plugging mechanism. The plugging mechanism is connected to the inner wall of the central tube via three sets of shear pins. The three sets of shear pins, from top to bottom, include an upper shear pin, a middle shear pin, and a lower shear pin. An expansion sleeve is also provided on the outer wall of the central tube on one side of the lower part of the plugging mechanism. The plugging mechanism works in conjunction with the expansion sleeve. Each set of shear pins is equipped with a stroke limiting groove. The three sets of stroke limiting grooves and the corresponding shear pins limit the position of the plugging mechanism during operation. The three positions from top to bottom correspond to the setting state, the drilling fluid internal and external flow state, and the unsealing state, respectively. The sealing mechanism includes a ball valve body, a ball valve seat, an upper drainage hole, a middle drainage hole, and a lower drainage hole. The ball valve body is a cylindrical hollow shell structure. A central channel connecting the upper and lower ends of the ball valve body is formed by welding a vertical pipe at the central axis of the ball valve body. There are multiple upper, middle, and lower drainage holes, which are opened on the outer wall of the ball valve body and evenly distributed around the axis of the ball valve body. Multiple radially arranged through holes are also evenly distributed around the axis on the ball valve body between the middle and lower drainage holes. The through hole is formed by a welded transverse pipe, one end of which passes through the central channel and the other end of which passes through the outer surface of the ball valve body. The outer wall of the ball valve body is connected to the inner surface of the central pipe by a cylindrical ball valve seat. The upper inner surface of the ball valve seat has an annular space around its axis. The inner wall of the ball valve seat, where the lower edge of the annular space is located, has multiple evenly distributed upper shear pins along the radial direction. The ends of the upper shear pins extend inward and enter the first stroke limiting groove formed on the outer wall of the ball valve body and arranged axially. The area below the upper shear pins... The inner wall of the ball valve seat has multiple evenly distributed channels that connect the inside and outside of the ball valve seat. A first outlet hole is provided on the wall of the central tube corresponding to channel one. Multiple evenly distributed, radially arranged intermediate shear pins are installed on the inner wall of the ball valve seat below channel one. The heads of the intermediate shear pins extend inward and enter a second stroke limiting groove provided on the outer wall of the ball valve seat along the axial direction. Multiple evenly distributed, radially arranged channels two are provided on the side wall of the ball valve seat below the intermediate shear pins. A second outlet hole is provided on the outer wall of the central tube opposite channel two. The valve body is provided with a second outlet hole. Multiple evenly distributed and radially arranged lower shear pins are installed on the inner wall of the ball valve seat below the second channel. The heads of the lower shear pins extend inward and enter the third stroke limiting groove formed on the outer wall of the ball valve body and arranged axially. The bottom end of the ball valve seat is folded inward to form an annular limiting plate, which is used to limit the lowest position of the ball valve body. The inner diameter of the first channel is smaller than the inner diameter of the second channel. The heights of the first stroke limiting groove, the second stroke limiting groove, and the third stroke limiting groove increase sequentially. In the initial state, the ball valve body is positioned by the upper shear pin, channel one and channel two are blocked by the ball valve body, the through hole is blocked by the inner wall of the ball valve seat, and the annular space is in a closed state. In the set-sealed state, the upper shear pin is sheared, the ball valve body moves downward along the axis and is positioned by the middle shear pin. At this time, the lower drain hole is opposite to the second channel, and the first channel continues to be blocked by the ball valve body, the through hole continues to be blocked by the ball valve seat, the upper end of the annular space is opened, and the upper drain hole is opposite to the annular space. When the drilling fluid is flowing inside and outside, the middle shear pin is sheared, the ball valve body moves down along the axis and is positioned by the lower shear pin. At this time, the lower drainage hole is still opposite to channel two, the middle drainage hole is opposite to channel one, the through hole continues to be blocked by the ball valve seat, the upper end of the annular space remains open, and the upper drainage hole continues to be opposite to the annular space. In the unsealed state, the lower shear pin is sheared, the bottom of the ball valve body abuts against the annular limiting plate, the lower drain hole and the through hole are both opposite to channel two, channel one is blocked by the ball valve body, the upper end of the annular space remains open, the upper drain hole continues to be opposite to the annular space, and the middle drain hole is blocked by the ball valve seat. The inner wall of the expansion tube is opposite to the outer wall of the central tube, and an annular groove is formed around the axis. The second liquid outlet hole passes through the bottom of the annular groove and is opposite to the inner wall of the expansion tube. The inner surface of the expansion tube located on the upper and lower sides of the annular groove is sealed and fixedly connected to the outer surface of the central tube.

2. The ball valve type downhole plugging device as described in claim 1, characterized in that: The throwing mechanism includes a horizontal tube, an arc-shaped tube, a compression spring, a piston, and a steel ball. One end of the horizontal tube is closed, and the open end is screwed to a threaded hole on the outer wall of the central tube. The piston is slidably connected inside the horizontal tube. A compression spring is connected between the inner end of the piston and the inner surface of the closed end of the horizontal tube. A limiting groove is formed at the lower end of the piston, and the steel ball is placed in the limiting groove. A limiting rod is also provided between the piston and the closed end of the horizontal tube. One end of the limiting rod is fixedly connected to the inner surface of the closed end of the horizontal tube, and the other end extends along the axis of the horizontal tube toward the piston. The limiting rod is used to limit the maximum distance the piston moves inward. The lower end of the horizontal tube is connected to an arc-shaped tube that slopes inward toward the central tube. The upper port and inner diameter of the arc-shaped tube are adapted to the size of the steel ball. In the initial state, the compression spring compresses the piston, and the piston closes the horizontal tube. When subjected to a certain pressure, the compression spring contracts, the lower port of the limiting groove aligns with the upper port of the arc-shaped tube, and the steel ball is thrown out along the arc-shaped tube.

3. The ball valve type downhole plugging device as described in claim 2, characterized in that: In the initial state, the top of the ball valve body and the ball valve seat form a continuous spherical groove. The spherical groove is used to guide the steel ball to the top of the central channel and block the central channel. The top of the ball valve body and the upper port of the central channel are provided with an annular magnet block for strongly adsorbing and positioning the steel ball.

4. The ball valve type downhole plugging device as described in claim 3, characterized in that: A pressure sensor is installed at the connection point between the drill string tip and the drilling equipment. In the event of a downhole overflow or well kick, the abnormal data detected by the pressure sensor is used to determine the occurrence of the overflow or well kick.

5. The method of using a ball valve type downhole plugging device as described in claim 4, comprising the following steps: Step 1: Running into the well while drilling: The ball valve type downhole plugging device is part of the downhole drill string and is lowered into the well along with the drill string during drilling. During normal drilling, the drilling fluid flows through the central channel of the ball valve body. The plugging device uses a stabilizer to prevent the plugging device from wearing out and damaging the expansion sleeve, thus preventing the plugging device from being scrapped prematurely. Step 2, Sealing Process: When encountering downhole overflow or well kick, high-pressure fluid rushes into the annulus outside the drill string. When the pressure in the annulus increases to a certain value, the piston moves inward to its maximum stroke. At this time, the steel ball falls and is thrown out along the arc-shaped tube, blocking the upper port of the central channel of the ball valve body. At this time, the drilling fluid in the drill string cannot flow into the central channel. When the drilling fluid is pressurized, the first stroke limit groove shears the upper shear pin, and the ball valve body moves downward. Under the resistance of the middle shear pin, it is repositioned. At this time, the top of the ball valve body and the ball valve seat are misaligned, and the top of the annular space is open. The drilling fluid in the drill string enters the ball valve body through the upper drainage hole. At this time, the middle drainage hole on the ball valve body and channels one and two are blocked, while the lower drainage hole is connected to channel two. The drilling fluid enters the annular groove through the lower drainage hole, channel two, and the second outlet hole, and is squeezed to expand the expansion sleeve, so that the expansion sleeve and the casing in the well are tightly pressed together, thereby sealing the annulus between the casing and the drill string. At this time, the setting seal is achieved. Step 3: Internal and external circulation process of drilling fluid: When the pressure sensor detects abnormal data, the pressure of the drilling fluid in the drill string is increased. The pressure is increased by increasing the density of the drilling fluid in the input drill string, which increases the pressure of the drilling fluid column above the ball valve body. This causes the middle shear pin to be sheared by the second stroke limiting groove, and the ball valve body moves downward. The lower shear pin moves upward along the third stroke limiting groove and positions the ball valve body. At this time, the middle drainage hole is connected to channel one, and the lower drainage hole is still connected to channel two. The drilling fluid enters the ball valve body from the upper drainage hole. Part of the drilling fluid flows out through channel two to maintain the setting state, and the other part of the drilling fluid flows out through the middle drainage hole, channel one, and the first outlet hole. The outflowing drilling fluid flows into the annulus between the drill string and the casing above the expansion sleeve to form the kill fluid in the annulus. This forms the circulation of drilling fluid inside and outside the drill string. As the height of the kill fluid in the annulus increases, the sealing force against well kick or overflow of drilling fluid in the annulus below the expansion sleeve is further enhanced. Step 4: Unsealing Process When high-density drilling fluid is injected into the wellhead for well control, the pressure of the liquid column above the ball valve body continues to increase. According to daily experimental data, the pressure of the liquid column above the ball valve body is made greater than the pressure of the high-pressure fluid below. At this time, the lower shear pin is sheared by the third stroke limiting groove, and the bottom end of the ball valve body abuts against the annular limiting plate. At this time, the drilling fluid enters the ball valve body from the upper drainage hole, while the middle drainage hole is blocked by the ball valve seat. The lower drainage hole is connected to channel two. At the same time, the through hole is also connected to channel two. The drilling fluid in channel two and the annular groove enters the drill string below the sealing mechanism through the through hole and the central channel. At this time, the drilling fluid in the drill string resumes the downward output state, the expansion sleeve contracts, and the device and casing are unsealed.

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