Blowout prevention device and well killing method thereof

Abstract

The invention relates to a blowout prevention device and a well killing method thereof, and belongs to the technical field of drilling engineering. Comprising a reducing flange, a covering type wellhead, a guide-in sealing hollow device, a lifting nipple and a plug valve, the reducing flange is detachably connected with the covering type wellhead, one end of the guide-in sealing hollow device extends into the covering type wellhead, the other end of the guide-in sealing hollow device is in threaded connection with the lifting nipple, and the other end of the lifting nipple is connected with the plug valve. A constructor completes well killing construction by connecting a well killing pipeline and injecting well killing fluid, the well killing fluid enters from a sleeve and returns out of an oil pipe, the well killing fluid of an original well is completely or partially replaced out, the pressure of a fluid column in the well is increased, and well blowout accident treatment is completed. The covering type well mouth is connected with the reducer union, then the sealed hollow device and the lifting short section are guided in in a matched mode to establish a well killing circulation channel, and finally the effect of effectively controlling blowout accidents is achieved.

Description

Technical Field

[0001] The invention relates to a blowout prevention device and a well killing method thereof, belonging to the technical field of drilling engineering. Background Art

[0002] During the oil and gas drilling process, blowouts may occur. Blowouts are a phenomenon in which fluids in the formation spray out of the ground or flow into other formations in the well. Blowouts mostly occur at the site of oil and gas extraction. In the event of a blowout, natural gas will burn if it encounters sparks after it sprays out, which is very dangerous. At the same time, the sprayed oil will pollute the surrounding environment, so it is necessary to prevent blowouts at the wellhead of the oil well.

[0003] There are two main types of blowout prevention devices in the prior art. The first device is mainly composed of a lifting nipple 60, a plug valve 50, a tubing head reducer 70 and a split spear. The second device is mainly composed of a lifting nipple 60, a plug valve 50, a tubing hanger 55 and a conversion joint 65, respectively. Figure 1 and Figure 2 As shown, when overflow occurs, the existing devices need to be connected to the wellbore string. Figure 1 The device needs to be installed with bolts. The 2 devices in the figure are fixed with the top screw and the load of the wellbore tubing. The installation time is about 2 minutes. The most time-consuming step is the connection stage with the wellbore tubing. The reasons for the long time are divided into five aspects. The first is the difficulty in lifting: the traditional blowout prevention wellhead is placed 2m away from the wellhead. When a dangerous situation occurs, the construction personnel need to lift the blowout prevention wellhead to the vicinity of the wellhead, and then lift it up and install it through the lifting equipment. During the whole operation process, it is easy to have the traveling block shaking and difficult to install, and the blowout prevention wellhead falls to the ground and injures workers. The second is the problem of centering: due to the influence of the shaking of the traveling block, it is difficult to align the traditional blowout prevention wellhead with the wellbore tubing, which reduces the success rate of the wellhead installation and affects the well sealing time; the third is the problem of buckling: the two traditional blowout prevention wellhead devices respectively use The first is to connect the wellbore tubing by means of a conversion joint and a split spear. Due to the influence of the fluid blowing out of the well, the connection is difficult and the failure rate is high, delaying the rescue time; the fourth is the difficulty of bolt entry into the hole: when the blowout prevention wellhead is successfully installed, it is difficult for the bolt to enter the four-way screw hole, and it is easy to cause damage to the bolt thread, resulting in failure of the wellhead installation; the fifth is the difficulty of bolt installation: when installing ordinary wellhead bolts, it is often difficult to thread the bolts, especially when the fluid is blowing out of the well, the threading problem will be more prominent, and the danger will be greatly increased for the construction personnel operating at the wellhead.

[0004] The existing well killing method first requires connecting the anti-blowout tool to the oil pipe, and then closing the casing to achieve plugging. The oil pipe and casing in the well form a well killing circulation channel. The construction personnel complete the well killing construction by connecting the well killing pipeline and injecting the well killing fluid. The well killing fluid enters from the casing and returns from the oil pipe (reverse circulation well killing), or enters from the oil pipe and returns from the casing (positive circulation well killing), replacing the original well killing fluid, increasing the pressure of the liquid column in the well, and completing the blowout accident treatment. The disadvantage of this well killing method is that the wellhead is not sealed and controlled in time, which delays the best time for rescue and is easy to expand the blowout accident. Summary of the invention

[0005] In order to solve the above-mentioned problems existing in the prior art, the present invention discloses a blowout prevention device and a well pressure method thereof, and provides a device that can automatically and quickly align and realize dual control of the oil pipe and casing at the same time, which can effectively control emergency situations such as overflow, well slug and blowout, and effectively suppress the spraying potential of the ejecta while carrying out emergency blowout.

[0006] The technical solution adopted by the present invention is a blowout prevention device, including a reducing flange, a covered wellhead, an inlet sealing hollow device, a lifting short section and a plug valve, one end of the inlet sealing hollow device extends into the covered wellhead, the other end of the inlet sealing hollow device is threadedly connected to the lifting short section, the other end of the lifting short section is connected to the plug valve, and the reducing flange is detachably connected to the covered wellhead.

[0007] Furthermore, the outer side of the reducer flange is provided with an outer steel ring groove and a fixing screw hole, and the inner side is provided with an inner steel ring groove and a connecting screw hole. The inner steel ring groove is used to seal the reducer flange and the casing four-way connection, and the outer steel ring groove is used to seal the reducer flange and the covered wellhead; the inner diameter of the reducer flange is smaller than the outer diameter, and the connecting screw hole is used to connect with the casing four-way; the fixing screw hole is used to connect with the covered wellhead.

[0008] Furthermore, the covered wellhead is integrally formed from a connecting head, a main body and a main body flange from top to bottom, a female buckle is provided on the inner side of the connecting head, and a plurality of bolt holes for connecting with a reducing flange are provided on the main body flange.

[0009] Furthermore, the introduction sealing hollow device is composed of a short-circuit joint and a guide shoe. The interior of the introduction sealing hollow device is hollow. The inner side of the short-circuit joint is provided with a thread connected to the lifting short section. The middle outer wall of the short-circuit joint is provided with a male buckle. The diameter of the guide shoe gradually decreases, and the end of the guide shoe is open.

[0010] The present invention also discloses a well killing method using a blowout prevention device, and the specific steps are as follows:

[0011] Step 1: During normal construction, the casing spool is connected to the connecting screw holes of the reducer flange; when an emergency occurs, the covered wellhead is hoisted above the reducer flange using a traveling pulley;

[0012] Step 2: When the covered wellhead is aligned with the reducer flange and the nut is tightened, the guide shoe of the sealing hollow device is just inserted into the wellhead oil pipe, and the sealing hollow device and the oil pipe in the well form a circulation channel;

[0013] Step three, rotate the lifting short section clockwise, and the construction personnel complete the well killing construction by connecting the well killing pipeline and injecting the well killing fluid. Due to the establishment of the circulation channel, the well killing fluid enters from the casing and returns from the oil pipe, or enters from the oil pipe and returns from the casing, replacing all or part of the original well killing fluid, increasing the liquid column pressure in the well, and completing the blowout accident handling.

[0014] The well killing fluid is configured to meet the requirements according to the pressure in the well, such as brine, mud, etc.

[0015] The circulation channel is composed of the oil pipe and casing in the well. The oil pipe divides the casing space into two parts: the oil pipe and the annular space. The well-killing fluid enters from the oil pipe and flows out of the casing, or the well-killing fluid enters from the casing and flows out of the oil pipe. The function of the circulation channel is to provide a channel for the well-killing fluid, replace the original well-killing fluid with high-density well-killing fluid such as brine, increase the pressure of the liquid column, and complete the blowout accident treatment.

[0016] The invention discloses a blowout prevention device and a well-killing method thereof, which has the beneficial effect of increasing the operating radius of wellhead construction personnel and improving construction safety by utilizing the large diameter of the reducer flange, saving the operation time of lifting the elevator up and down, reducing the labor intensity of workers, and effectively realizing rapid closure of the wellhead in case of emergency situations such as blowouts, reducing the probability of accident complications, improving the safety of workers' rescue, and gaining a time advantage for the next step of well-killing treatment. A covered wellhead and a reducer are connected, and then a sealing hollow device and a lifting short section are introduced to establish a well-killing circulation channel, thereby finally achieving the effect of effectively controlling blowout accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 Shown is a schematic diagram of the first blowout prevention device in the prior art;

[0019] Figure 2 Shown is a schematic diagram of a second blowout prevention device in the prior art;

[0020] Figure 3 Shown is a cross-sectional schematic diagram of embodiment 1 of the present invention;

[0021] Figure 4 The figure shows a cross-sectional view of a reducing flange in Embodiment 1 of the present invention;

[0022] Figure 5 Shown is a schematic diagram of introducing a sealed hollow device in Example 1 of the present invention.

[0023] As shown in the figure: 10. Reducer flange; 11. Inner steel ring groove; 12. Connecting screw hole; 13. Outer steel ring groove; 14. Fixing screw hole; 20. Covered wellhead; 21. Connector; 22. Main body; 23. Main body flange; 24. Female buckle; 25. Bolt hole; 26. Groove; 30. Introducing sealing hollow device; 31. Short connector; 32. Male buckle; 33. Guide shoe; 34. Guide shoe opening; 50. Plug valve; 55. Tubing hanger; 60. Lifting nipple; 65. Conversion joint; 70. Tubing head reducer; 80. Petal fishing.

[0024] Specific implementation methods

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to further understand the content of the present invention, the present invention is further described below in conjunction with specific implementation methods.

[0027] Example 1: Figures 3 to 5As shown, a blowout prevention device includes a reducer flange 10, a covered wellhead 20, an inlet sealing hollow device 30, a lifting nipple 60 and a plug valve 50. The covered wellhead 20 is formed from a connector 21, a main body 22 and a main body flange 23 from top to bottom. A female buckle 24 is provided on the inner side of the connector 21, and a plurality of bolt holes 25 for connecting with the reducer flange 10 are provided on the main body flange 23. An introduction sealing hollow device 30 is installed above the covered wellhead 20. The introduction sealing hollow device 30 is composed of a short-circuit joint 31 and a guide shoe 33. The guide shoe 33 of the introduction sealing hollow device 30 is extended into the oil pipe below the covered wellhead 20 by rotating through the connector 21 to achieve sealing. The introduction sealing hollow device 30 is threadedly connected to the covered wellhead 20 through a male buckle 32. A lifting short section 60 is installed above the introduction sealing hollow device 30. The lifting short section 60 is fixed to the introduction sealing hollow device 30 through threads. A plug valve 50 is installed above the lifting short section 60. The plug valve 50 is fixed to the lifting short section 60 through threads. The fixing screw holes 14 of the reducing flange 10 are connected to the main flange 23 through matching bolts, the outer steel ring groove 13 of the reducing flange 10 is sealed with the groove 26 of the covering wellhead 20 through the steel ring, the inner steel ring groove 11 below the reducing flange 10 is sealed with the casing four-way through the steel ring, and the internal connecting screw holes 12 of the reducing flange 10 are connected to the casing four-way through bolts.

[0028] Furthermore, the diameter of the guide shoe 33 from top to bottom gradually decreases from 77 mm to 48 mm.

[0029] Furthermore, the covered wellhead 20 is made of 25CrNiMo, which is suitable for a well control pressure of 35 MPa and meets all current well control requirements of oil fields. Its installation conditions are suitable for the situation where the wellhead tubing is sitting on the hanging card, shortening the rescue time. The wellhead can be directly buckled by connecting with the reducer flange 10, thereby achieving the purpose of controlling the oil pipe and casing at the same time.

[0030] Furthermore, the matching bolt is a hexagonal nut at one end, which is embedded in the main flange 23 and has a thread at the other end. Only one nut needs to be screwed to complete the connection between the reducer flange 10 and the covered wellhead 20.

[0031] The specific steps of the well killing method based on the blowout prevention device are as follows:

[0032] Step 1: During normal construction, the casing spool is connected to the connecting screw hole 12 of the reducer flange 10; when an emergency occurs, the covered wellhead 20 is hoisted above the reducer flange 10 by a traveling pulley;

[0033] Step 2: After the covered wellhead 20 and the reducer flange 10 are installed, the guide shoe 33 of the sealing hollow device 30 is just inserted into the wellhead oil pipe, and the guide shoe opening 34 is connected to the oil pipe;

[0034] Step 3: Rotate the lifting sub 60 clockwise, inject the well-killing liquid through the tubing, and let the liquid flow out of the casing to establish a well-killing circulation channel.

[0035] The rapid rescue operation method uses a covered wellhead to achieve the purpose of first control and then pressure. When an emergency such as overflow or well kick occurs, the wellhead control work is completed first to prevent the blowout accident from expanding and delaying the best time for rescue. Then the sealing hollow device is rotated to complete the seal with the oil pipe in the well to form a circulation channel. The construction personnel complete the well killing construction by connecting the well killing pipeline and injecting salt water and other well killing fluids. Due to the establishment of the circulation channel, the well killing fluid enters from the casing and returns from the oil pipe (reverse circulation well killing), or enters from the oil pipe and returns from the casing (positive circulation well killing), establishes a circulation, replaces all or part of the original well killing fluid, increases the pressure of the liquid column in the well, and completes the blowout accident treatment.

[0036] Well killing fluid: Well killing fluid that meets the requirements is configured according to the pressure in the well, such as brine, mud, etc.

[0037] Well-killing circulation channel: It is composed of the oil pipe and casing in the well. The oil pipe divides the casing space into two parts: the oil pipe and the annular space. The space that the well-killing fluid enters from the oil pipe and exits from the casing, or enters from the casing and exits from the oil pipe is the well-killing circulation channel.

[0038] The function of the circulation channel is to provide a channel for the well-killing fluid, replace the original well-killing fluid with high-density well-killing fluid such as brine, increase the liquid column pressure, and complete the blowout accident treatment.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A blowout prevention device, comprising a lifting nipple (60) and a plug valve (50), wherein the lifting nipple (60) is connected to the plug valve (50), and characterized in that: It also includes a reducing flange (10), a covering wellhead (20) and an inlet sealing hollow device (30), wherein one end of the inlet sealing hollow device (30) extends into the covering wellhead (20), and the other end of the inlet sealing hollow device (30) is threadedly connected to a lifting short section (60), and the reducing flange (10) and the covering wellhead (20) are detachably connected.

2. The blowout prevention device according to claim 1, characterized in that: An outer steel ring groove (13) and a fixing screw hole (14) are arranged on the outer side of the reducing flange (10), and an inner steel ring groove (11) and a connecting screw hole (12) are arranged on the inner side of the reducing flange (10). The inner steel ring groove (11) is used to seal the reducing flange (10) and the casing four-way connection, and the outer steel ring groove (13) is used to seal the reducing flange (10) and the covering wellhead (20). The inner diameter of the reducing flange (10) is smaller than the outer diameter, and the connecting screw hole (12) is used to connect with the casing four-way connection; the fixing screw hole (14) is used to connect with the covering wellhead (20).

3. The blowout prevention device according to claim 2, characterized in that: The covered wellhead (20) is integrally formed from top to bottom by a connector (21), a main body (22) and a main body flange (23); a female buckle (24) is provided on the inner side of the connector (21); and a plurality of bolt holes (25) for connecting with a reducer flange (10) are provided on the main body flange (23).

4. The blowout prevention device according to claim 1, characterized in that: The introduction sealing hollow device (30) is composed of a short-circuit joint (31) and a guide shoe (33). The interior of the introduction sealing hollow device (30) is hollow. The inner side of the short-circuit joint (31) is provided with a thread connected to the lifting short section (60). The middle outer wall of the short-circuit joint (31) is provided with a male buckle (32). The diameter of the guide shoe (33) is gradually reduced, and the end of the guide shoe (33) is open.

5. The blowout prevention device according to claim 4, characterized in that: The diameter of the guide shoe (33) decreases gradually from 77 mm to 48 mm from top to bottom.

6. A method for killing a well using the blowout prevention device according to claim 1, characterized in that: The specific steps are as follows: Step 1: During normal construction, the casing spool is connected to the connecting screw hole (12) of the reducing flange (10); when an emergency occurs, the covered wellhead (20) is hoisted above the reducing flange (10) by a traveling pulley; Step 2: When the covered wellhead (20) and the reducer flange (10) are aligned and the nut is tightened, the guide shoe (33) of the sealing hollow device (30) is just inserted into the wellhead oil pipe, and the sealing hollow device (30) and the oil pipe in the well form a circulation channel; Step 3, the lifting sub (60) is rotated clockwise, and the construction personnel complete the well killing construction by connecting the well killing pipeline and injecting the well killing fluid. Due to the establishment of the circulation channel, the well killing fluid enters from the casing and returns from the oil pipe, or enters from the oil pipe and returns from the casing, so that the original well killing fluid is completely or partially replaced, the liquid column pressure in the well is increased, and the blowout accident treatment is completed.

7. The well killing method according to claim 6, characterized in that: The well-killing fluid is prepared with brine or mud that meets the requirements according to the pressure in the well.

8. The well killing method according to claim 6, characterized in that: The circulation channel is composed of the oil pipe and casing in the well. The oil pipe divides the casing space into two parts: the oil pipe and the annular space.

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