CN112282697A - Downhole safety valve - Google Patents

Abstract

The invention relates to the technical field of safety valves, and particularly discloses an underground safety valve which comprises an upper joint, a piston cylinder, a spring cavity and a lower joint which are sequentially connected through threads, wherein the upper joint, the piston cylinder, the spring cavity and the lower joint are all made of metal materials; a piston hole is formed in the piston cylinder, a piston assembly is arranged in the piston hole, and the piston assembly can slide in the piston hole; a power spring is arranged in the spring cavity, the lower end of the piston assembly is connected with a push rod, and the push rod penetrates through the power spring; the inner hole at the lower end of the spring cavity is connected with a sealing valve body; the upper joint is provided with a hydraulic control pipeline connecting port, the lower end of the hydraulic control pipeline connecting port is connected with a pressure transmitting port, and the upper end of the pressure transmitting port is provided with a conical sealing surface; the hydraulic control pipeline connecting port is provided with straight threads, and two sides of the lower end of the hydraulic control pipeline connecting port respectively extend upwards in an inclined mode to form detection holes; the invention has the advantages that the performance is not easy to change under the conditions of high pressure and high temperature, the stability of the product is improved, and the risk of safety accidents is reduced.

Description

Downhole safety valve

Technical Field

The invention relates to the technical field of safety valves, in particular to an underground safety valve.

Background

An underground safety valve is an emergency safety device during oil and gas exploitation. When the underground operation is completed or unexpected safety accidents occur, such as blowout and well kick, the safety valve is closed, so that potential risks or accidents can be avoided. Most of the downhole safety valves on the market at present have lower pressure grades, which generally do not exceed 10000psi, while the safety valves with ultrahigh pressure grades can reach 20000psi, and the performance is often not stable enough, so that the safety valves fail.

The technical problems of the ultra-high pressure underground safety valve in the current market mainly comprise: under the condition of high pressure, the connection between the main parts is easy to leak; when the hydraulic control pipeline interface bears high pressure, leakage is easy to occur; when the hydraulic control pipeline is blocked accidentally and the pressure cannot be relieved, the direct loosening of the threads is dangerous, and high safety accidents are caused.

Disclosure of Invention

Aiming at the problems that leakage and high safety accident risk are easy to occur to the ultrahigh pressure underground safety valve, the invention provides the underground safety valve, the performance of the underground safety valve is not easy to change under the conditions of high pressure and high temperature, the stability of a product is improved, and the safety accident risk is reduced.

In order to solve the technical problems, the invention provides the following specific scheme:

a downhole safety valve comprises an upper joint, a piston cylinder, a spring cavity and a lower joint which are sequentially connected through threads, wherein the upper joint, the piston cylinder, the spring cavity and the lower joint are made of metal materials;

a piston hole is formed in the piston cylinder, a piston assembly is arranged in the piston hole, and the piston assembly can slide in the piston hole;

a power spring is arranged in the spring cavity, the lower end of the piston assembly is connected with a push rod, and the push rod penetrates through the power spring;

the inner hole at the lower end of the spring cavity is connected with a sealing valve body;

the upper joint is provided with a hydraulic control pipeline connecting port, the lower end of the hydraulic control pipeline connecting port is connected with a pressure transmitting port, and the upper end of the pressure transmitting port is provided with a conical sealing surface; the hydraulic control pipeline connecting port is provided with straight threads, and two sides of the lower end of the hydraulic control pipeline connecting port extend obliquely upwards to form detection holes respectively.

Optionally, the lower end of the piston cylinder is connected with an extension cylinder, the extension cylinder is fixedly connected with the piston cylinder through a set screw, and the extension cylinder can right the piston assembly, so that the piston assembly is centered.

Optionally, the hole upper end of push rod is equipped with the recess, install the scraping ring in the recess, the scraping ring can slide on extending a section of thick bamboo, and the scraping ring can play the effect of cleaing away debris, avoids debris to pile up the stability that influences the use.

Optionally, the outer surfaces of the piston assembly, the extension cylinder and the push rod are respectively subjected to xylitol coating treatment, so that abrasion caused by relative movement of parts can be effectively prevented, and the stability of a product is improved.

Optionally, a positioning ring is embedded in the front end of the inner hole of the extension cylinder, so that the functions of centering and centering the piston assembly are achieved.

Optionally, the piston assembly comprises a piston, the upper end of the piston is connected with a piston seat, the lower end of the piston is connected with a piston rod, and the outer surface of the piston is provided with a sealing assembly;

a support ring is arranged between the piston and the piston seat, and a support ring is arranged between the piston and the piston rod;

the lower end of the piston rod is connected with the push rod, and the piston, the piston rod and the push rod are in linkage action.

Optionally, an inclined plane is arranged at the upper end of the piston hole, and a step matched with the inclined plane is arranged at the upper end of the piston seat to play a role in sealing the metal surface and the metal surface, so that pressure and liquid at the upper end of the sealing valve body cannot enter the piston cylinder, and the purpose of reducing the leakage rate of the downhole safety valve is achieved.

Optionally, the inner hole of the lower joint is provided with a shoulder, and the lower end of the push rod is provided with a lower end surface matched with the shoulder, so that dirt is prevented from entering the sealing surface of the sealing valve body and the spring cavity;

the push rod is provided with an exhaust hole, and the arrangement of the exhaust hole can avoid the formation of metal seal, namely, the formation of a closed space in the spring cavity.

Optionally, the surface of the lower end of the push rod is subjected to nitriding and hardening treatment, so that the risk that the front end of the push rod is bent or damaged to prevent the push rod from being incapable of normally opening the sealing valve body due to repeated pushing and opening of the sealing valve body is avoided.

Optionally, a bearing assembly is arranged between the upper end of the power spring and the push rod, and when the power spring is mounted on the bearing assembly, deformation and distortion caused by excessive torque transmitted to the power spring when the threads are tightened are avoided.

Compared with the prior art, the invention has the beneficial effects that: according to the underground safety valve provided by the invention, the main parts are connected in a threaded and metal sealing manner, and the metal surface is sealed with the metal surface, so that the performance is not easy to change under the conditions of high pressure and high temperature, the stability of the product is improved, and the purpose of reducing the leakage rate of the underground safety valve is achieved;

the pressure transfer port of the upper joint is designed into a straight thread and metal seal connection mode, the two sealing surfaces are pushed to be in contact for sealing while the threads are tightened, the tighter the threads are screwed, the better the sealing surfaces are in contact, the more reliable the sealing effect is, and the operation is easy;

when passing the pressure mouth and appearing leaking the condition, have liquid to flow from two inspection holes, the effect of being convenient for to detect is played in the setting of inspection hole, and when hydraulic control pipeline unexpected jam and unable pressure release, only need loosen a bit threaded connection, pressure will release from two inspection hole departments, has reduced the risk that the incident takes place.

Drawings

Fig. 1 is a schematic view of an overall structure of a downhole safety valve in a closed state according to an embodiment of the present invention.

Fig. 2 is an enlarged view of a portion a of fig. 1.

Fig. 3 is an enlarged view of a portion B of fig. 1.

Fig. 4 is an enlarged view of a portion C of fig. 1.

Fig. 5 is a sectional view taken in the direction D-D of fig. 4.

Fig. 6 is a schematic view of an overall structure of an open state of a downhole safety valve according to an embodiment of the present invention.

Fig. 7 is a schematic structural diagram of an upper joint provided in the embodiment of the present invention.

Fig. 8 is an enlarged view of a portion E of fig. 7.

Fig. 9 is a sectional view in the direction F-F in fig. 8.

Fig. 10 is a schematic view of the connection of the upper joint with the hydraulic line.

Fig. 11 is an enlarged view of a portion G in fig. 10.

Wherein, 1 is an upper joint; 101 is a hydraulic control pipeline connecting port; 102 is a pressure transmission port; 103 is a detection hole; 2 is a piston cylinder; 21 is a piston; 22 is a piston seat; 23 is a piston rod; 24 is a seal assembly; 241 is a sealing ring; 242 is a V-shaped packing; 25 is a support ring; 26 is an inclined plane; 3 is a spring cavity; 4 is a lower joint; 41 is a shoulder; 5 is a power spring; 6 is a push rod; the 61 is an exhaust hole; 7 is a sealing valve body; 71 is a valve seat; 72 is a valve clack frame; 73 is a valve flap; 74 is a fixed seat; 75 is a pin; 76 is a pin sleeve; 77 is a torsion spring; 78 is a fastening screw; 79 is a fixing screw; 8 is an extension cylinder; 9 is a set screw; 10 is a scraping ring; 11 is a positioning ring; 12 is a bearing assembly; 121 is an upper bearing ring; 122 is a bearing ball; 123 is a roller fixer; 124 is a lower bearing ring; 13 is a hydraulic control pipeline; and 14 is a pilot-controlled pipeline joint.

Detailed Description

In order to explain the technical solution of the present invention in detail, the technical solution of the embodiment of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiment of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

For example, the downhole safety valve comprises an upper joint, a piston cylinder, a spring cavity and a lower joint which are sequentially connected through threads, wherein the upper joint, the piston cylinder, the spring cavity and the lower joint are made of metal materials; a piston hole is formed in the piston cylinder, a piston assembly is arranged in the piston hole, and the piston assembly can slide in the piston hole; a power spring is arranged in the spring cavity, the lower end of the piston assembly is connected with a push rod, and the push rod penetrates through the power spring; the inner hole at the lower end of the spring cavity is connected with a sealing valve body; the upper joint is provided with a hydraulic control pipeline connecting port, the lower end of the hydraulic control pipeline connecting port is connected with a pressure transmitting port, and the upper end of the pressure transmitting port is provided with a conical sealing surface; the hydraulic control pipeline connecting port is provided with straight threads, and two sides of the lower end of the hydraulic control pipeline connecting port respectively extend upwards in an inclined mode to form detection holes.

The safety valve in pit that this embodiment provided, under the high pressure high temperature condition, the performance is difficult for changing, has improved product stability, has reduced the risk that the incident takes place.

As shown in fig. 1 to 11, the downhole safety valve comprises anupper joint 1, apiston cylinder 2, aspring cavity 3 and alower joint 4 which are sequentially connected through threads, wherein the lower end of the upper joint is connected with the upper end of the piston cylinder, the lower end of the piston cylinder is connected with the upper end of the spring cavity, and the lower end of the spring cavity is connected with the upper end of the lower joint. In this example, specifically, the lower end inner surface of the upper joint is connected to the upper end outer surface of the piston cylinder, the lower end outer surface of the piston cylinder is connected to the upper end inner surface of the spring cavity, and the lower end outer surface of the spring cavity is connected to the upper end inner surface of the lower joint.

The upper joint, the piston cylinder, the spring cavity and the lower joint are made of metal materials, namely, the upper joint, the piston cylinder, the spring cavity and the lower joint are connected in a threaded and metal sealing mode, the metal surface is sealed with the metal surface, the performance is not prone to change under the high-pressure and high-temperature condition, the product stability is improved, and the purpose of reducing the leakage rate of the safety valve is achieved.

Be equipped with the piston hole in the piston section ofthick bamboo 2, be equipped with piston assembly in the piston hole, at specific operation in-process, piston assembly can slide in the piston hole.

Apower spring 5 is arranged in thespring cavity 4, the lower end of the piston assembly is connected with a push rod 6, and the push rod penetrates through the power spring; the lower end inner hole of the spring cavity is connected with asealing valve body 7.

Theupper joint 1 is provided with a hydraulic controlpipeline connecting port 101, the lower end of the hydraulic controlpipeline connecting port 101 is connected with apressure transmitting port 102, and the upper end of thepressure transmitting port 102 is provided with a conical sealing surface; the hydraulic controlpipeline connecting port 101 is provided with straight threads, and two sides of the lower end of the hydraulic controlpipeline connecting port 101 extend obliquely upwards to formdetection holes 103.

The connection mode of a hydraulic control pipeline connector of a common underground safety valve is generally a sealing pipe thread NPT connection mode or a connection mode of a straight thread and a sealing conical surface, the NPT of the common sealing pipe thread needs to be wound with a raw rubber belt to play a sealing role, and the raw rubber belt is easy to lose efficacy to cause pipeline leakage under a high-pressure working condition environment; if a straight thread and sealing cone connection is used, the sealing effect is achieved by squeezing the sealing cone to deform, which is generally not ideal and relatively troublesome. As shown in fig. 7-11, in this example, a straight thread and metal seal connection is adopted, and a tapered sealing surface is provided, so that the sealing is realized by pushing the two sealing surfaces to contact while tightening the threads, the tighter the threads are tightened, the better the sealing surfaces are contacted, the more reliable the sealing effect is, and the operation is easy. The setting of two inspection holes can be convenient for detect, the condition of leaking appears when passing the pressure mouth, will have liquid to leak out from two inspection holes, and,hydraulic control pipeline 13 passes through hydrauliccontrol pipeline joint 14 and fixes on last joint, whenhydraulic control pipeline 13 the unexpected jam appears and can't the pressure release, need unscrew the connecting thread of port department, if there are not two inspection holes, it can be very dangerous directly to loosen the screw thread, and these two inspection holes have, only need loosen a bit, pressure will release from two inspection hole departments, the risk that the incident takes place has been reduced.

Under normal conditions, the sealing valve body is in a normally open state, as shown in figure 1, when unexpected safety accidents such as blowout and well kick occur, the sealing valve body is closed, and the accidents can be avoided. When the sealing valve needs to be closed, the pressure of thehydraulic control pipeline 13 is released through the ground, the piston assembly slides in the piston hole under the action of the power spring and contracts back to drive the push rod to move upwards, the sealing valve body is closed after losing the support of the push rod, and the effect of blocking the underground pressure is achieved, as shown in fig. 6. On the contrary, when the sealing valve body needs to be opened, the pressure is applied to the pressure transfer port on the side surface of the upper joint through the ground control pipeline, the pressure of the hydraulic control pipeline pushes the piston assembly and the push rod to move, meanwhile, the power spring is compressed, the push rod pushes the sealing valve body to be pushed open, and pressurization is continued until the sealing valve body is completely opened. At this time, the sealing valve body is always in an open state as long as the pressure of the control pipeline is not released.

Referring to fig. 1 and 4, the sealingvalve body 7 includes avalve seat 71, avalve flap frame 72, avalve flap 73, a fixingseat 74, apin 75, apin sleeve 76, atorsion spring 77, and afastening screw 78, the valve seat is connected to an inner hole at the lower end of the spring cavity through a thread, the valve flap frame is connected to the valve seat through thefastening screw 78, the valve flap is connected to the valve seat through the pin, the pin sleeve is sleeved on the pin, the pin and the pin sleeve pass through the torsion spring, the fixing screws 79 are installed at two ends of the pin to prevent the pin from sliding out, and the valve flap frame and the fixing seat are connected.

Under normal conditions, the valve clack is in a normally open state, and when unexpected safety accidents occur, such as blowout and well kick, the valve clack is closed to avoid the accidents. When the valve clack needs to be closed, the pressure of the hydraulic control pipeline is released through the ground, the piston assembly slides in the piston hole under the action of the power spring and contracts back to drive the push rod to move upwards, the valve clack loses the support of the push rod and is closed downwards under the action of the torsion spring to form sealing with the valve seat, and the effect of blocking the underground pressure is achieved. On the contrary, when the valve clack needs to be opened, pressure is applied to the pressure transmission port on the side face of the upper joint through the ground control pipeline, the pressure of the hydraulic control pipeline pushes the piston assembly and the push rod to move, meanwhile, the power spring is compressed, the push rod pushes the valve clack open, and pressurization is continued until the valve clack is completely opened. At this time, the valve flap is always in the open state as long as the pressure in the control line is not released.

In some embodiments, the lower end of thepiston cylinder 2 is connected with anextension cylinder 4, the extension cylinder and the piston cylinder are fixedly connected through aset screw 9, and the extension cylinder can right the piston assembly, so that the piston assembly is centered.

The upper end of the inner hole of the push rod 6 is provided with a groove, ascraping ring 10 is installed in the groove, the scraping ring can slide on the extension cylinder, the scraping ring can play a role in clearing sundries, and the storage stability of the sundries which affect the use is avoided.

In some embodiments, the outer surfaces of the piston assembly, the extension cylinder and the push rod are respectively subjected to xylitol coating treatment, so that abrasion caused by relative movement of parts can be effectively prevented, and the stability of a product is improved.

The underground safety valve is an emergency safety device for oil and gas exploitation, can work stably for a long time, has high requirements on product materials, is made of chromium alloy materials under the working condition environment containing hydrogen sulfide or carbon dioxide, has good corrosion resistance but low hardness, and is easy to generate friction damage during relative sliding, so that special surface treatment is needed. The outer surfaces of the piston assembly, the extension cylinder and the push rod are respectively subjected to xylitol coating treatment, and the surface coating treatment can effectively prevent parts from being abraded during relative movement, so that the product stability is improved.

In some embodiments, a retainingring 11 is embedded in the front end of the inner bore of the extension cylinder 8 to serve as a centering and centering piston assembly.

As shown in fig. 3, the piston assembly includes apiston 21, apiston seat 22 is connected to the upper end of the piston, apiston rod 23 is connected to the lower end of the piston, and a sealingassembly 24 is arranged on the outer surface of the piston; asupport ring 25 is arranged between the piston and the piston seat, and a support ring is arranged between the piston and the piston rod; the lower end of the piston rod is connected with the push rod, and the piston, the piston rod and the push rod are in linkage action. Wherein, the outer surfaces of the piston seat, the piston rod and the support ring are all subjected to xylitol coating treatment.

The sealing assembly that the piston surface set up is total two sets ofly, a set of sealing assembly is located the upper end of piston, another sealing assembly of group is located the lower extreme of piston, each sealingassembly 24 of group is all including asealing ring 241 and two V type roots ofcoils 242, after receiving power spring's elastic force effect, piston and piston rod are back to shrink, at the piston towards retrieving the in-process that contracts, can extrude sealing assembly, V type roots of coils receives extrusion deformation, can cooperate the sealing ring to play fine sealed effect.

In some embodiments, the upper end of the piston hole is provided with aninclined surface 26, and the upper end of the piston seat is provided with a step matched with the inclined surface, so that the metal surface and the metal surface are sealed, pressure and liquid at the upper end of the sealing valve body cannot enter the piston cylinder, and the purpose of reducing the leakage rate of the downhole safety valve is achieved.

When releasing hydraulic control pipeline pressure, piston assembly is under power spring's effect, and back shrink, and the inclined plane in piston hole can the butt finally to the piston seat, forms metal seal, and pressure and the liquid of sealing valve body upper end just can't enter into the piston cylinder like this, play the purpose that reduces the subsurface safety valve leakage rate. In the example, the piston assembly is made of a non-elastomer sealing material with good sealing performance, the performance is stable and reliable under a high-pressure working environment, and a double-protection effect is achieved.

In some embodiments, the inner hole of the lower joint 4 is provided with ashoulder 41, the lower end of the push rod is provided with a lower end surface matched with the shoulder, and dirt is reduced from entering a sealing surface of the sealing valve body and a spring cavity; the push rod 6 is provided with anexhaust hole 61, and the arrangement of the exhaust hole can avoid the formation of metal seal, namely, the formation of a closed space in the spring cavity.

When the sealing valve body is completely opened, the lower end face of the push rod can abut against the shoulder of the lower connector, so that the dirt can be reduced from entering the sealing surface of the sealing valve body and the spring cavity, but in order to avoid forming metal seal, the front end of the push rod is provided with the exhaust hole, and therefore a closed space cannot be formed in the spring cavity.

In some embodiments, the lower end surface of the push rod is subjected to nitriding and hardening treatment, so that the risk that the front end of the push rod is bent or damaged to prevent the seal valve body from being opened normally due to repeated pushing and opening of the push rod is avoided.

A bearingassembly 12 is arranged between the upper end of thepower spring 5 and the push rod 6, and when the power spring is installed, deformation and distortion which are possibly caused by excessive torque transmitted to the power spring when threads are tightened are avoided.

As shown in fig. 2, the bearingassembly 12 includes anupper bearing ring 121, abearing ball 122, aball retainer 123 between the upper and lower bearing rings for retaining the bearing balls, and alower bearing ring 124, and avoids deformation distortion that may be caused by excessive torque transmitted to the power spring when tightening the threads when installing the power spring.

The underground safety valve provided by the invention has the advantages that the performance is not easy to change under the conditions of high pressure and high temperature, the stability of the product is improved, and the risk of safety accidents is reduced.

It is understood that different embodiments among the components in the above embodiments can be combined and implemented, and the embodiments are only for illustrating the implementation of specific structures and are not limited to the implementation of the embodiments.

The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims (10)

1. The underground safety valve is characterized by comprising an upper joint (1), a piston cylinder (2), a spring cavity (3) and a lower joint (4) which are sequentially connected through threads, wherein the upper joint (1), the piston cylinder (2), the spring cavity (3) and the lower joint (4) are all made of metal materials;

a piston hole is formed in the piston cylinder (2), a piston assembly is arranged in the piston hole, and the piston assembly can slide in the piston hole;

a power spring (5) is arranged in the spring cavity (3), the lower end of the piston assembly is connected with a push rod (6), and the push rod (6) penetrates through the power spring (5);

the inner hole at the lower end of the spring cavity (3) is connected with a sealing valve body (7);

the upper joint (1) is provided with a hydraulic control pipeline connecting port (101), the lower end of the hydraulic control pipeline connecting port (101) is connected with a pressure transmitting port (102), and the upper end of the pressure transmitting port (102) is provided with a conical sealing surface;

the hydraulic control pipeline connecting port (101) is provided with straight threads, and two sides of the lower end of the hydraulic control pipeline connecting port (101) extend obliquely upwards to form detection holes (103).

2. A downhole safety valve according to claim 1, wherein an extension cylinder (8) is connected to the lower end of the piston cylinder (2), and the extension cylinder (8) is fixedly connected to the piston cylinder (2) by a set screw (9).

3. A downhole safety valve according to claim 2, wherein the push rod (6) is provided with a groove at the upper end of its inner bore, and a wiper ring (10) is mounted in the groove, the wiper ring (10) being slidable on the extension cylinder (8).

4. A downhole safety valve according to claim 2, wherein the outer surfaces of the piston assembly, the extension cylinder (8) and the push rod (6) are each treated with a xylitol coating.

5. A downhole safety valve according to claim 2, wherein a retaining ring (11) is embedded in the front end of the inner bore of the extension barrel (8).

6. A downhole safety valve according to claim 1, wherein the piston assembly comprises a piston (21), a piston seat (22) is connected to the upper end of the piston (21), a piston rod (23) is connected to the lower end of the piston (21), and a sealing assembly (24) is arranged on the outer surface of the piston (21);

a support ring (25) is arranged between the piston (21) and the piston seat (22), and a support ring (25) is arranged between the piston (21) and the piston rod (23);

the lower end of the piston rod (23) is connected with a push rod (6).

7. A downhole safety valve according to claim 6, wherein the upper end of the piston bore is provided with a ramp (26) and the upper end of the piston seat (22) is provided with a step cooperating with the ramp (26).

8. A downhole safety valve according to claim 1, wherein the inner bore of the lower joint (4) is provided with a shoulder (41), and the lower end of the push rod (6) is provided with a lower end surface matching the shoulder (41);

the push rod (6) is provided with an exhaust hole (61).

9. A downhole safety valve according to claim 1, wherein the lower end surface of the push rod (6) is nitrided and hardened.

10. A downhole safety valve according to claim 1, wherein a bearing assembly (12) is arranged between the upper end of the power spring (5) and the push rod (6).

Images