1. A floating seal assembly, characterized by: the device comprises a floating sealing element, a transition short section and an adjusting short section;

the floating sealing element comprises an upper half seal, a sealing short section, a slip and a lower half seal; the upper half seal is connected with the upper end of the sealing short section through a sealing short section upper flange, the sealing short section is connected with the upper end of the slip through a sealing short section lower flange, and the lower end of the slip is connected with the lower half seal;

the transition short section is connected with the lower half-sealing lower end through a transition short section upper flange, and a transition short section lower flange is arranged at the lower end of the transition short section;

the adjusting short section is connected with the lower flange of the transition short section through an upper adjusting short section flange, and the adjusting short section is connected with the working blowout preventer through a lower adjusting short section flange.

2. A floating seal assembly according to claim 1, wherein: and the upper half seal is internally provided with a flashboard and a sealing rubber piece which have the same specification with the sealing oil pipe.

3. A floating seal assembly according to claim 1, wherein: the inner diameter of the sealing short section is larger than the outer diameter of the opening tool, and the height of the sealing short section is not smaller than the length of the opening tool.

4. A floating seal assembly according to claim 1, wherein: and a flashboard assembly and slip teeth which are consistent with the specifications of an oil pipe at the lower part of the open tool are arranged in the slip and used for clamping the pipe column and preventing the floating sealing device from moving under the action of pressure in the well.

5. A floating seal assembly according to claim 1, wherein: and a semi-seal gate plate and a sealing rubber piece which have the same specification with the oil pipe at the lower part of the opening tool are arranged in the lower semi-seal, and the semi-seal gate plate and the sealing rubber piece and the slips form a double-gate-plate blowout preventer.

6. A pressurized workover treatment method for starting an open tool by using a floating seal device comprises the following steps:

step one, 1 tubing coupling which is plugged at the upper part of a downhole openness tool is lifted to the position above a working blowout preventer, and a tubing string in a well is clamped by a safety slip;

step two, sequentially installing an adjusting short section lower flange, an adjusting short section upper flange and an adjusting short section lower flange connected with the lower part of the transition short section on the working blowout preventer;

step three, opening the safety slips, matching the traveling block, and lifting the opening tool to the lower side of the working blowout preventer under pressure;

step four, clamping the safety slips, and sequentially sleeving a transition short section, a transition short section upper flange and a floating sealing element from the top of an oil pipe at the upper part of the open tool;

fifthly, the transition short section penetrates through the floating slip and is connected and fixed with the adjusting short section through the transition short section upper flange, the transition short section lower flange and the floating sealing element in sequence;

step six, closing the upper half seal, slowly opening the working blowout preventer and opening the safety slip;

step seven, matching the traveling block, and lifting the open tool into the floating sealing cavity;

step eight, closing the lower semi-seal and the slip, pressing down the hydraulic cylinder, and clamping the floating slip;

step nine, removing a connecting bolt between the transition short section and the adjusting short section, and removing the fixation of the floating sealing device;

lifting a hydraulic cylinder of the under-pressure operation machine, and lifting the tubing coupling at the lower part of the opening tool into the under-pressure operation machine;

and step eleven, adopting a segmented oil pipe internal pressure control technology, and carrying out back-off under pressure to lift out the opening tool.

Background

The essence of the pressurized workover process is a pressure control operation, which is an environment-friendly workover operation technology comprising oil pipe internal pressure control and oil sleeve ring pressure control.

The pressure control in the oil pipe of the normal pressurized workover operation is implemented before the air pressure control of the oil sleeve, and the pressure in the well is blocked by using oil pipe pressure control tools such as an oil pipe plug, an oil pipe bridge plug and the like, so that the fluid in the well can not be ejected out of the oil pipe in the process of the air pressure control. Therefore, the pressure control in the oil pipe of the pressurized workover operation mostly belongs to the 'prior' control.

The method for controlling the pressure in the oil pipe during the pressurized workover operation is limited by the structure of the pipe column, and the method for controlling the pressure in the oil pipe is different for pipe columns with different structures.

For the tubular columns of open tools with communicated oil pipes and sleeves, such as a fracturing tubular column with a sand blaster, a perforating tubular column with a reverse circulation valve, a natural gas well production tubular column with a gas lift valve, a separate-layer water injection tubular column with an eccentric water distributor and the like, the pressure in the well can be cut off only by plugging the upper oil pipe and the lower oil pipe of the open tools in advance respectively, the fluid in the well is prevented from being sprayed out from the open tools in the process of lifting the tubular columns under pressure, and the well control and environmental protection hidden troubles are reduced.

In the actual oil pipe internal pressure control industry, the inner diameter of a tool connected to the upper part of an underground openness tool is smaller, an oil pipe internal pressure control tool in the oil pipe cannot plug the oil pipe at the lower part of the openness tool through the tool with the smaller inner diameter at the upper part, and in the process of lifting a pipe column under pressure, fluid in the well is sprayed out of a well mouth along an oil sleeve communication channel of the openness tool, so that well control and environmental protection accidents are caused.

In order to realize well control safety during workover operations, three methods are often used for wells with an open-end tool in a downhole string:

1) pressure reversing buckle

The method adopts a segmented oil pipe internal pressure control technology, uses a safety slip and a safety full-seal blowout preventer to be matched, sets an opening tool with an oil pipe internal pressure control tool in 1 oil pipe on the upper part, and implements under-pressure back-off in a safety blowout preventer group with pressure operation to lift the opening tool.

When the under-pressure back-off is carried out, the distance between the safety slip and the upper safety full-sealing blowout preventer is required to be at least not less than the length of the open tool string, and the well can be closed in time after the under-pressure back-off is ensured. The technical requirement inevitably needs to increase the height of the safety blowout preventer stack, and the position of the working platform of the pressurized working machine is raised, so that the operation is inconvenient.

In addition, the under-pressure back-off is only suitable for tubing coupling and is not suitable for downhole tools. When the fish is inverted under pressure, the tool is easy to be inverted and scattered, so that the fish top is complicated.

2) Cutting with pressure

Aiming at the defect that the tools are easy to fall apart by the aid of the pressure reversing buckles, 1 pressure cutting device is additionally arranged in the safety blowout preventer group, an oil pipe at the lower part of the open tool is cut by a cutting tool, and the open tool is lifted out by closing the full-seal blowout preventer.

Although the cutting method with pressure avoids the risk of scattering open tools, sealed fishing is needed after cutting, the operation procedure is complex, the operation cost is high, and the method is not suitable for popularization.

3) Killing well operation or blowout depressurization

The well killing fluid is adopted for killing the well, so that the well control problem is solved, but the well killing fluid has to damage a reservoir stratum and influence the productivity. The open flow depressurization operation has the environment-friendly pressure and can influence the service life of the casing due to the excitation of the bottom pressure.

Disclosure of Invention

Aiming at a well of an open tool with communicated oil pipes and sleeves, such as a fracturing pipe column with a sand blaster, a perforating pipe column with a reverse circulation valve, a natural gas well production pipe column with a gas lift valve, a separate-layer water injection pipe column with an eccentric water distributor and the like, the invention is difficult to carry out bottleneck of operation under pressure, and in order to realize well control safety, the invention expands the concept of operation sealing space under pressure, provides a floating sealing device and an operation method for repairing the well under pressure for lifting the open tool, and achieves the purposes of safe and environment-friendly operation.

The invention provides the following technical scheme:

a floating sealing device comprises a floating sealing element, a transition short section and an adjusting short section;

the floating sealing element comprises an upper half seal, a sealing short section, a slip and a lower half seal; the upper half seal is connected with the upper end of the sealing short section through a sealing short section upper flange, the sealing short section is connected with the upper end of the slip through a sealing short section lower flange, and the lower end of the slip is connected with the lower half seal;

the transition short section is connected with the lower half-sealing lower end through a transition short section upper flange, and a transition short section lower flange is arranged at the lower end of the transition short section;

the adjusting short section is connected with the lower flange of the transition short section through an upper adjusting short section flange, and the adjusting short section is connected with the working blowout preventer through a lower adjusting short section flange.

In the technical scheme, the upper half seal is internally provided with the flashboard and the sealing rubber piece which have the same specification with the sealing oil pipe.

In the technical scheme, the inner diameter of the sealing short section is larger than the outer diameter of the opening tool, and the height of the sealing short section is not smaller than the length of the opening tool.

In the technical scheme, the slip is internally provided with the gate plate assembly and the slip teeth which are consistent with the specifications of an oil pipe at the lower part of the open tool and are used for clamping the pipe column and preventing the floating sealing device from moving under the action of the pressure in the well.

In the technical scheme, the lower semi-seal is internally provided with a semi-seal gate plate and a sealing rubber piece which have the same specification with the lower oil pipe of the opening tool, and the semi-seal gate plate and the sealing rubber piece and the slips form the double-gate-plate blowout preventer.

A pressurized workover treatment method for starting an open tool by using a floating seal device comprises the following steps:

step one, 1 tubing coupling which is plugged at the upper part of a downhole openness tool is lifted to the position above a working blowout preventer, and a tubing string in a well is clamped by a safety slip;

step two, sequentially installing an adjusting short section lower flange, an adjusting short section upper flange and an adjusting short section lower flange connected with the lower part of the transition short section on the working blowout preventer;

step three, opening the safety slips, matching the traveling block, and lifting the opening tool to the lower side of the working blowout preventer under pressure;

step four, clamping the safety slips, and sequentially sleeving a transition short section, a transition short section upper flange and a floating sealing element from the top of an oil pipe at the upper part of the open tool;

fifthly, the transition short section penetrates through the floating slip and is connected and fixed with the adjusting short section through the transition short section upper flange, the transition short section lower flange and the floating sealing element in sequence;

step six, closing the upper half seal, slowly opening the working blowout preventer and opening the safety slip;

step seven, matching the traveling block, and lifting the open tool into the floating sealing cavity;

step eight, closing the lower semi-seal and the slip, pressing down the hydraulic cylinder, and clamping the floating slip;

step nine, removing a connecting bolt between the transition short section and the adjusting short section, and removing the fixation of the floating sealing device;

lifting a hydraulic cylinder of the under-pressure operation machine, and lifting the tubing coupling at the lower part of the opening tool into the under-pressure operation machine;

and step eleven, adopting a segmented oil pipe internal pressure control technology, and carrying out back-off under pressure to lift out the opening tool.

The invention has the advantages and beneficial effects that:

the invention discloses a floating sealing device and a pressurized workover operation method for an open tool, aiming at downhole tools which are used in oil and gas wells and have communicated oil casings such as sand blasters and eccentric water distributors and cannot be plugged by an oil pipe internal pressure control tool in the pressurized workover operation process. The principle of the invention is that an open tool belt is pressed to a sealing device which is arranged at the upper part of a working blowout preventer and consists of two half-seal ram blowout preventers symmetrically arranged at two sides of a short section; the hydraulic cylinder of the pressurized operation machine is lifted, so that the open tool is lifted out of the well mouth together with the pipe column in a sealed state in the sealed cavity, and the purpose of safe and environment-friendly operation is achieved.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention.

The hydraulic control system comprises a hydraulic control system, a hydraulic control system and a hydraulic control system, wherein 1 is an upper half seal, 2-1 is a sealing short section upper flange, 2-2 is a sealing short section lower flange, 2-3 is a transition short section upper flange, 2-4 is a transition short section lower flange, 2-5 is an adjusting short section upper flange, 2-6 is an adjusting short section lower flange, 3 is a sealing short section, 4 is a slip, 5 is a lower half seal, 6 is a transition short section, 7 is a moving slip, 8 is an adjusting short section, 9 is a working blowout preventer, and 10 is a lifting hydraulic cylinder.

For a person skilled in the art, other relevant figures can be obtained from the above figures without inventive effort.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the present invention is further described below with reference to specific examples.

Example 1

A floating sealing device comprises a floating sealing element, a transition short section and an adjusting short section;

the floating sealing element is a closed space formed by five devices, namely an upper half seal 1, a connecting flange 2, a sealing short joint 3, a slip 4 and a lower half seal 5, and has the functions of accommodating an opening tool therein and sealing the pressure in the well from the opening tool.

The upper half seal 1 is internally provided with a flashboard and a sealing rubber piece which have the same specification with a sealing oil pipe, and is arranged above the sealing short section 3 through a sealing short section upper flange 2-1, and the upper half seal has the function of sealing an oil pipe body at the upper part of an open tool when the upper half seal 1 is closed, so that well fluid from the lower part cannot overflow from the upper part of the sealing short section; two ends of the sealing short joint 3 are respectively connected with an upper sealing short joint flange 2-1 and a lower sealing short joint flange 2-2 through threads, the inner diameter of the sealing short joint is larger than the outer diameter of the opening tool, the height of the sealing short joint is not smaller than the length of the opening tool, and the sealing short joint is used for accommodating the opening tool in the sealing short joint; the slip 4 is arranged below the sealing short section 3 through a sealing short section lower flange 2-2, is internally provided with a flashboard assembly and slip teeth which have the same specification with an oil pipe at the lower part of the opening tool and is used for clamping a pipe column and preventing the floating sealing device from moving under the action of pressure in a well; the lower semi-seal 5 is arranged below the slips 4 in an inverted mode, the lower semi-seal 5 and the slips 4 can form a double-ram blowout preventer, and a semi-seal ram and a sealing rubber piece which are consistent with the specifications of an oil pipe at the lower part of the opening tool are installed inside the double-ram blowout preventer and used for sealing the pressure in the upper sealing short circuit when the lower semi-seal 5 is closed.

The transition short section 6 is respectively connected with the lower semi-seal 5 and the adjusting short section 8 through the transition short section upper flange 2-3 and the transition short section lower flange 2-4, is respectively used for sealing the pressure in a well and fixing the floating sealing device, provides a working space for controlling the floating sealing device to lift by the moving slip 7, and can control the pipe column to jack up when the floating sealing connection is released.

The adjusting short section 8 is a connecting part between the transition short section 6 and the working blowout preventer, and when the connecting bolts of the connecting flange 2 at the upper part of the adjusting short section 8 and the connecting flange 2 at the lower part of the transition short section 6 are removed, the fixed state of the floating sealing device is released by the floating slip 7.

The moving slip 7 is a bearing component of the operation machine with pressure, moves up and down along with the hydraulic cylinder 10, and is used for pressing a pipe column with pressure and controlling the pipe column to be jacked up.

The working blowout preventer 9 is a pressure-bearing assembly of a pressure operation machine and is used for controlling the annular pressure of an oil sleeve when a pipe column is lifted under pressure.

Example 2

A pressurized workover treatment method for starting an open tool by using a floating seal device comprises the following steps:

step one, 1 tubing coupling which is plugged at the upper part of a downhole openness tool is lifted to the position above a working blowout preventer 9, and a tubing string in a well is clamped by a safety slip;

step two, sequentially installing an adjusting short section lower flange 2-6, an adjusting short section 8, an adjusting short section upper flange 2-5 and a transition short section lower flange 2-4 connected with the lower part of the transition short section 6 on the working blowout preventer 9;

step three, opening the safety slips, matching the traveling block, and lifting the opening tool to the lower side of the working blowout preventer 9 under pressure;

step four, clamping the safety slips, and sequentially sleeving a transition short section 6, a transition short section upper flange 2-3 and a floating sealing device from the top of an oil pipe on the upper part of the open tool;

step five, the transition short section 6 penetrates through a floating slip 7 and is connected with a fifth connecting flange 2-5 at the upper part of an adjusting short section 8 and a floating sealing device in sequence;

step six, closing the upper half seal 1, slowly opening the working blowout preventer 10 and opening the safety slips in sequence;

step seven, matching the traveling block, and lifting the open tool into the floating sealing cavity;

step eight, closing the lower semi-seal and the slip, pressing down the hydraulic cylinder 10, and clamping the floating slip 7;

step nine, removing a connecting bolt between the transition short section 6 and the adjusting short section 8, and removing the fixation of the floating sealing device;

lifting a hydraulic cylinder of the under-pressure operation machine, and lifting the tubing coupling at the lower part of the opening tool into the under-pressure operation machine;

and step eleven, adopting a segmented oil pipe internal pressure control technology, and carrying out back-off under pressure to lift out the opening tool.

In this embodiment, the open downhole tool includes a sand blaster, a reverse circulation valve, a gas lift valve, an eccentric water distributor, etc. with an oil jacket communication function. The invention provides a pressurized workover operation method for pulling out an open tool by adopting a floating sealing device, aiming at downhole tools which are used in oil and gas wells and have communicated oil casings such as sand blasters and eccentric water distributors and cannot be plugged by an oil pipe internal pressure control tool in the process of pressurized workover operation. The principle of the invention is that an open tool is pressed to a sealing device which is arranged at the upper part of a working blowout preventer and is formed by symmetrically arranging two semi-closed ram blowout preventers at two sides of a short section; the hydraulic cylinder of the pressurized operation machine is lifted, so that the open tool is lifted out of the well mouth together with the pipe column in a sealed state in the sealed cavity, and the purpose of safe and environment-friendly operation is achieved.

The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.