RU2794031C1 - Method for successively lowering two pipe strings with downhole equipment into a well and a device for its implementation - Google Patents

Abstract

FIELD: means of oil and gas wells.

SUBSTANCE: means for sealing the mouth of oil and gas wells during tripping operations (TO) in wells equipped with a double-row pipe string. In particular, the claimed method of successively lowering two pipe strings with downhole equipment into the well includes installing and fastening a preventer on the support flange of the wellhead valve with the help of studs and nuts, lowering and securing two pipe strings. A preventer with large bore diameter is fixed onto the support flange of the wellhead flange, then the first pipe string is lowered into the well, after the first pipe string is lowered into the well, a pipe holder is screwed onto its upper end, then the first pipe string is allowed into the well and the pipe holder is installed in the support flange of the wellhead valve. On the top flange of the preventer, with the help of studs and nuts, the lower flange of the additional preventer with a smaller bore diameter, made with eccentricity, is fastened, then through the smaller bore diameter of the additional preventer, and then the second pipe string is lowered. After lowering the second pipe string into the well, its upper end is fixed in the pipe holder, after which the preventer and the additional preventer are dismantled, and the upper flange of the wellhead valve is installed on its support flange. A device for implementing said method is also claimed.

EFFECT: simplification and provision of successive running of TO with two strings of pipes with downhole equipment without dismantling the preventer between TOs with two strings of pipes of different diameters.

2 cl, 4 dwg

Description

The invention relates to methods and devices designed to seal the mouth of oil and gas wells using a preventer installed at the wellhead on various sizes of supporting flanged wellhead fittings, in particular for carrying out tripping operations (TR) in wells equipped with a double-row pipe string with downhole equipment (simultaneously separate production, simultaneous separate injection) in order to ensure safety, prevent and eliminate oil and gas manifestations (OGVP), protect the subsoil and the environment.

A known method of installing a ram preventer on the wellhead valve support flange (patent RU No. 2632721, publ. 10/09/2017), including hermetic fastening of the preventer by the lower flange on the wellhead valve support flange, during tripping operations, the equipment on the pipe string is moved through a vertical axial channel preventer body. To close the preventer, i.e. sealing of the pipe string lowered into the well, by turning the handwheels in the clockwise direction, the pipe rams are closed until they are completely wrapped around the outside of the pipe string, and to open the preventer after depressurizing, it is necessary to retract the pipe rams by rotating the handwheels counterclockwise to the initial position until the vertical axial channel of the preventer body is fully opened .

The disadvantages of the method:

- firstly, the complexity of the installation (mounting-dismantling) of the preventer on the support flange of the wellhead equipment in the process of successive running of two strings of pipes of different diameters, for example, two strings of tubing with an outer diameter of 60 and 48 mm, with downhole equipment associated with disassembly of wellhead fittings. This is due to the fact that during the tripping of the first or second row of the pipe string with downhole equipment, it is necessary to: dismantle the preventer after the trip with the first row of the pipe string with downhole equipment, disassemble the wellhead valves, replace the replaceable ring, mount the preventer on the support flange of the wellhead valve for running second row of pipe string with downhole equipment;

- secondly, the duration of wellhead valve dismantling, as well as the dismantling-mounting of the preventer on the wellhead valve support flange in the process of successive lowering of two strings with downhole equipment, associated with the need to replace the replaceable ring on the wellhead valve;

- thirdly, the low safety of work by maintenance personnel at the wellhead in the process of consecutive descent of two strings of pipes with downhole equipment. This is due to the fact that after tripping the first row of the pipe string with downhole equipment, it is necessary to first dismantle the preventer from the support flange of the wellhead equipment, and then re-mount the preventer on the other flange, after fixing it to the wellhead, in order to trip the first row of the pipe string with downhole equipment. Therefore, during this period of time, the wellhead remains open for 10-15 minutes, which can lead to the occurrence of OGWP and the creation of a critical situation in the well.

A ram preventer is known (patent RU No. 2632721, publ. 09.10.2017), containing a preventer with a cast lower flange, which is hermetically mounted on the support flange of the wellhead valve. The preventer contains upper and lower flanges rigidly connected to the body, the body is equipped with a vertical round axial channel, side horizontal channels are symmetrically located relative to the axial channel, the longitudinal axes of the side horizontal channels are located perpendicular to the axis of the vertical channel, in the first horizontal channels made in the body with the possibility of longitudinal movement, ram blocks are installed, in which pipe rams are placed, equipped with elastic seals, and manual drives for controlling rams, including ram drive rods having threaded connections for interacting with covers screwed into the body, while the cavities of the ram block bodies in cross section have a rectangular shape, and elastic seals are placed in the grooves made in the pipe rams. The lower blind rams placed in the ram block directly cover the vertical axial channel of the body, and their bodies are the bodies of the ram blocks, the bodies of the upper pipe rams are rectangular in cross section and are placed in the rectangular recesses of the lower ram bodies with the possibility of movement, while elastic seals are placed in shaped grooves made in the bodies of the dies, and the longitudinal axes of the drive rods of the dies are spaced relative to each other in a vertical diametrical plane and interact with two threaded holes of the cover.

The disadvantages of the device are:

- firstly, the impossibility of consecutive tripping of two strings of pipes of different diameters, for example, two strings of tubing with an outer diameter of 60 and 48 mm, with downhole equipment without disassembling the wellhead valves and dismantling and mounting the preventer on the support flange of the wellhead a string of pipes of a different diameter;

- secondly, the laboriousness of work associated with the disassembly and assembly of wellhead valves;

- thirdly, high costs for the manufacture of replaceable rings of various sizes.

The closest in terms of technical essence and the achieved result is a method for sequentially lowering two pipe strings into the well with downhole equipment, including installation and fastening with the help of studs and nuts of a preventer on the support flange of the wellhead valve, lowering and securing two pipe strings (patent RU No. 2724695, IPC E21B 33/06, published 06/25/2020). Lifting lugs are preliminarily installed on the preventer body at an angle of 180° with respect to each other and offset relative to each other in the vertical plane, a preventer is selected with the minimum connecting and sealing dimensions of the lower flange corresponding to the support flange of the wellhead valve, the lower flange of the preventer is hermetically connected to with a replaceable ring of a larger standard size than the lower flange, but corresponding to the dimensions of the wellhead valve support flange, then the preventer with a replaceable ring is lifted by the lifting eyes with an inclination angle corresponding to the inclination angle of the wellhead wellhead support flange and hermetically fixed on the wellhead valve support flange, while the replaceable ring is made with connecting and sealing dimensions equal to the standard sizes of the wellhead valve support flanges, and if it is necessary to attach the preventer to the wellhead valve support flange of a different size, the installed replaceable ring is replaced with another replaceable ring corresponding to the wellhead valve support flange on which the preventer will be mounted .

The disadvantages of the method are:

- firstly, the complexity of installing (mounting-dismantling) a preventer on the support flange of the wellhead equipment in the process of successive running of two strings of pipes of different diameters, for example, two strings of tubing with an outer diameter of 60 and 48 mm, with downhole equipment associated with disassembly of wellhead fittings. This is due to the fact that during the tripping of the first or second row of the pipe string with downhole equipment, it is necessary to: dismantle the preventer after the trip with the first row of the pipe string with downhole equipment, disassemble the wellhead valves, replace the replaceable ring, mount the preventer on the support flange of the wellhead valve for running second row of pipe string with downhole equipment;

- secondly, the duration and laboriousness of wellhead valve dismantling, as well as the dismantling and mounting of the preventer on the wellhead valve support flange in the process of successive lowering of two strings with downhole equipment, associated with the need to replace the replaceable ring on the wellhead wellhead valve;

- thirdly, the low safety of work by maintenance personnel at the wellhead in the process of consecutive descent of two strings of pipes with downhole equipment. This is due to the fact that after tripping the first row of the pipe string with downhole equipment, it is necessary to first dismantle the preventer from the support flange of the wellhead equipment, and then re-mount the preventer on the other flange, after fixing it to the wellhead, in order to trip the first row of the pipe string with downhole equipment. Therefore, during this period of time, the wellhead remains open for 10-15 minutes, which can lead to the occurrence of OGWP and the creation of a critical situation in the well.

The closest in technical essence and the achieved result is a preventer containing a preventer with a large bore diameter with cast lower and upper flanges, the lower eccentric flange of the preventer with a smaller bore section is hermetically mounted on the support flange of the wellhead valve using studs and nuts (patent RU No. 2724695, IPC E21B 33/06, published 06/25/2020). The lower flange of the preventer is made with connecting and sealing dimensions corresponding to the minimum dimensions of the wellhead valve support flange, while the preventer is equipped with a replaceable ring made with connecting and sealing dimensions corresponding to the dimensions of the wellhead valve support flange on which the preventer is attached, and the replaceable ring is installed under the lower flange with the possibility of hermetic fastening by bolting, the lower flange of the preventer is equipped with a metal ring, and the connecting size of the lower flange corresponds to the center-to-center diameter of the bolted connection, made in a replaceable ring, lifting eyes are rigidly fixed on the preventer body with a height offset relative to each other with the possibility of installing the preventer on the wellhead inclined well, and the replaceable ring is made with annular grooves with the possibility of installing sealing metal rings.

The disadvantages of the device are:

- firstly, the impossibility of consecutive tripping of two strings of pipes of different diameters, for example, two strings of tubing with an outer diameter of 60 and 48 mm, with downhole equipment without disassembling the wellhead valves and dismantling and mounting the preventer on the support flange of the wellhead a string of pipes of a different diameter;

- secondly, the laboriousness of work associated with the disassembly and assembly of wellhead valves;

- thirdly, low safety in the implementation of the SPO and high costs for the manufacture of replaceable rings of various sizes.

The technical objectives of the proposal are to simplify and ensure consistent execution of tripping with two strings of pipes with downhole equipment without dismantling the preventer between trips with two strings of pipes of different diameters, reducing labor intensity and reducing the duration of disassembling wellhead valves and mounting (dismantling) of the preventer on the support flange of wellhead valves, while improving the safety of work by maintenance personnel at the wellhead in the process of successively running two strings of pipes with downhole equipment, as well as expanding the arsenal of means for sequentially performing tripping with two strings of pipes with downhole equipment without dismantling the preventer between running trips with two strings of pipes of different diameters.

Technical problems are solved by the method of successively lowering two pipe strings with downhole equipment into the well, including the installation and fastening of a preventer on the support flange of the wellhead valve with the help of studs and nuts, running and securing two pipe strings.

What is new is that a preventer with a large bore diameter is attached to the support flange of the wellhead with the help of studs and nuts; pipe hanger, then the first pipe string is allowed into the well and the pipe hanger is installed in the support flange of the wellhead without dismantling the preventer; diameter of the additional preventer, and then through the larger diameter of the preventer, the second pipe string equipped with downhole equipment is lowered, after lowering the second pipe string into the well, its upper end is fixed in the pipe holder, after which the preventer and the additional preventer are dismantled, and the upper flange is installed on the support wellhead valve flange.

Technical problems are solved by a device for successively lowering two strings of pipes with downhole equipment into the well, containing a preventer with a cast upper and lower flange with a large bore diameter, hermetically fixed by the lower flange on the support flange of the wellhead with the help of studs and nuts.

What is new is that the support flange of the wellhead valve is equipped with a pipe hanger, and on the upper flange of the preventer with a large bore diameter, with the help of studs and nuts, an additional preventer with a smaller bore diameter is attached to the lower flange with eccentricity - e relative to the axial channel.

In FIG. 1 shows a blowout preventer mounted on a wellhead valve flange.

In FIG. 2 shows a preventer on the wellhead valve flange with the first string of pipes with a pipe hanger lowered.

In FIG. Figure 3 shows BOPs installed on the wellhead valve flange prior to running the second pipe string.

In FIG. Figure 4 shows BOPs installed on the wellhead valve flange when running the second pipe string.

The device for successively lowering two strings of pipes with downhole equipment into the well consists of a preventer 1 (Fig. 1-4) with a large bore diameter with a cast lower flange 2 and a cast upper flange 3. The preventer 1 is fixed by the lower flange 2 hermetically to the support flange 4 wellhead fittings using studs and nuts. The support flange 4 of the wellhead fitting is equipped with a pipe holder 5 (Fig. 2-4). On the upper flange 3 of the preventer 1 with a large bore diameter, with the help of studs and nuts, an additional preventer 6 (Fig. 3-4) with a smaller bore diameter is hermetically fixed. The preventer 6 has a cast lower flange 7, made with an eccentricity - e relative to the axial channel of the preventer 6. The tightness of the lower flange 2 of the preventer 1 and the support flange 4 of the wellhead valve, as well as the upper flange 3 of the preventer 1 with the lower flange 7 of the preventer 6 is ensured using a metal ring 8 (FIGS. 1-4) and 9 (FIGS. 3-4).

Carrying out sequential descent into the well of two strings of pipes with downhole equipment is performed in the following sequence.

The sealing metal ring 8 is installed in the corresponding annular groove (shown in Fig. 1) of the support flange 4 of the wellhead valve.

The preventer 1 with a nominal diameter of 180 mm is lifted and centered relative to the support flange 4 of the wellhead valve by means of a lifting unit and lowered down until the bottom flange 2 is seated on the support flange 4 of the wellhead valve. Then, with the help of studs and nuts, the preventer 1 is attached to the support flange 4. The tightness of the flange connection is ensured by the metal ring 8.

After the preventer 1 is installed, tripping operations are carried out with the first pipe string 10 (Fig. 2-4). After lowering the first pipe string 10 (Fig. 2-4) with downhole equipment, a pipe hanger 5 with a diameter of 170 mm is screwed onto the end of the string and the first pipe string is allowed into the well to the seat for the pipe hanger 5 in the support flange 4 of the wellhead valve (Fig. 2) . Since the diameter of the pipe hanger 5 is smaller than the nominal diameter of the preventer 1, this allows the pipe hanger 5 to be installed in the support flange 4 of the wellhead valve without dismantling the preventer 1 (Fig. 2).

To run the second string of pipes 11 (Fig. 4) with downhole equipment, the sealing metal ring 9 is installed in the corresponding annular groove of the upper flange 3 of the preventer 1 with a nominal diameter of 180 mm.

The preventer 6 with a nominal diameter of 80 mm is raised by means of a lifting unit and the axial channel of the preventer 6 and the hole for the second pipe string 11 in the pipe holder 5 are aligned and lowered until the lower cast flange 7 of the preventer 6 fits on the upper flange 3 of the preventer 1 (Fig. 3) . Then, with the help of studs and nuts, preventer 6 is attached to preventer 1. The tightness of the flange connection is ensured by a metal ring 9.

The second string of pipes 11, equipped with downhole equipment, is lowered first through the smaller bore diameter of 80 mm of the additional preventer 6, and then through the larger bore diameter of 180 mm of the preventer 1. After the second string of pipes 11 is lowered into the well, its upper end is fixed in the pipe holder 5. ( Fig. 4).

After lowering two strings of pipes with downhole equipment into the well and completion of work, preventers 1 and 6 are dismantled in reverse order and the upper flange of the wellhead valve is installed.

The invention makes it possible to carry out tripping operations in wells with a double-row pipe string with downhole equipment (simultaneously separate production, simultaneous separate injection) in order to ensure safety, prevent and eliminate oil and gas manifestations, protect the subsoil and the environment).

For example, on the first string of pipes with an outer diameter of 60 mm according to GOST 633-80 and a length of 1200 m, a downhole rod pump is lowered to ensure production from the lower formation.

For example, on the second string of pipes with an outer diameter of 48 mm according to GOST 633-80, a length of 800 m, a deep-well rod pump is lowered to ensure production from the upper layer.

When performing the method, it is not required to remount the equipment during tripping and the wellhead is always protected from OGWP.

The invention makes it possible to simplify the process of successively running two strings of pipes of different diameters with downhole equipment into the well, since after running the first string of pipes with downhole equipment, an additional preventer is installed without dismantling the main preventer, and work is continued associated with running the second string of pipes with downhole equipment .

Reduces labor intensity and reduces the duration of the process of consecutive descent of two strings with downhole equipment, as technological operations for disassembling wellhead valves, mounting and dismantling of a preventer on the support flange of wellhead equipment for running the second pipe string with downhole equipment are eliminated, which means it saves financial costs for repairs wells. The exclusion of replaceable rings of various sizes from the design of the device allows to reduce the cost of their manufacture.

EFFECT: increased safety of work by maintenance personnel at the wellhead in the process of consecutive descent of two pipe strings with downhole equipment. This is due to the fact that due to the exclusion of technological operations for the dismantling of the wellhead valve, the installation and dismantling of the preventer in the event of an OGVP, it is always possible to close the wellhead with a preventer located on the support flange of the wellhead valve.

The invention allows:

- perform sequential tripping with two strings of pipes of different diameters with downhole equipment without dismantling the preventer between trips with two strings of pipes of different diameters;

- to reduce the labor intensity of work related to the disassembly and assembly of wellhead valves and to reduce the duration of installation (dismantling) of the preventer on the wellhead valve support flange;

- eliminate the cost of manufacturing interchangeable rings of various sizes;

- to increase the safety of work by maintenance personnel at the wellhead in the process of successive lowering of two pipe strings with downhole equipment.

Claims (2)

1. A method for successively lowering two pipe strings with downhole equipment into the well, including installing and fastening a preventer on the wellhead valve support flange using studs and nuts, lowering and securing two pipe strings, characterized in that on the wellhead valve support flange using studs and nuts, a preventer with a large bore diameter is fixed, then through a larger bore diameter of the preventer, the first pipe string equipped with downhole equipment is lowered, after the first pipe string is lowered into the well, a pipe holder is screwed onto its upper end, then the first pipe string is allowed into the well and the pipe hanger is installed in the support flange of the wellhead valve without dismantling the preventer, then the lower flange, made with eccentricity, of the additional preventer with a smaller bore diameter is attached to the upper flange of the preventer, then, first, through the smaller bore diameter of the additional preventer, and then through the larger bore diameter of the preventer, running the second pipe string equipped with downhole equipment, after lowering the second pipe string into the well, its upper end is fixed in the pipe hanger, after which the preventer and the additional preventer are dismantled, and the upper flange of the wellhead valve is installed on the support flange of the wellhead valve. 2. A device for successively lowering two strings of pipes with downhole equipment into the well, containing a preventer with a cast upper and lower flange with a large bore diameter, hermetically fixed by the lower flange on the support flange of the wellhead valve using studs and nuts, characterized in that the support flange wellhead fitting is equipped with a pipe hanger, and on the upper flange of the preventer with a large bore diameter, with the help of studs and nuts, an additional preventer with a smaller bore diameter is attached to the lower flange with eccentricity - e relative to the axial channel.

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