RU2652776C1 - Method of manufacture of thermally insulated casing string and casing string implemented by this method - Google Patents

Abstract

FIELD: manufacturing technology.

SUBSTANCE: group of inventions refers to a method for manufacturing a thermally insulated casing string and a thermally insulated casing string. Method for manufacturing a thermally insulated casing string comprises supplying a thermal insulating material to the annular annular space formed by coaxially installed inner and outer tubes in each section, the projecting joints of the inner pipes are fixed with a collapsible connecting device, the outer pipes are covered with a shell, the cavity between the inner pipes and the shell is filled with thermal insulation. Before the pipes are assembled in the wall of the upper and lower part of the outer tube of each section, through holes are provided for the escape of gases and provide them with removable plugs for sealing.

EFFECT: technical result is a reduction in the thermal conductivity of the structure.

2 cl, 1 dwg

Description

The invention relates to the oil and gas industry and can be used for thermal insulation of casing strings and their sections installed in permafrost rocks to prevent their thawing around wells during operation.

Thermally insulated casing strings are used to ensure the stability of the estuarine zone and maintain effective thermal conditions to prevent complications associated with the formation of holes around the wells, including estuarine funnels during thawing of subsidence, cavernous permafrost (ice layers, ice veins, ice soils, highly highly subsidence rocks) adjacent to the surface to a depth of not more than 100 m:

- during the construction and operation of gas and oil wells;

-when placing and operating cluster wells to prevent the closure of halos of thawing of permafrost of adjacent wells in the upper part of the cryolite zone.

Known thermally insulated column according to the patent of Russia for the invention No. 2197594, IPC E21B 17/01, 43/00, F16L 59/14, publ. 09/10/2000, including concentrically located sections of external pipes with a connection unit and sections of internal pipes, in the annular space between which are thermally insulating and shielding materials, expansion joints, elastic rings installed between adjacent pipe sections in the connection unit. Compensators of thermal expansion are located at one end of the inner pipe and are rigidly connected by one cylindrical end of the shell to the outer surface of the inner pipe, and the other cylindrical end of the shell is mounted slide-movably on the inner pipe and rigidly connected to the inner surface of the outer pipe, the bending radii of the expansion joint are equal one third of the annular space gap, and the distance between the inner walls of the base of the loop-shaped bracket is h = 2 / 3R, where h - p Normal distance between the inner walls of the base loop staples mm; R is the bending radius of the bracket, mm

A disadvantage of the known design of thermally insulated pipes is the difficulty of manufacturing, increased weight and limitation of the depth of descent, due to the fact that thermal insulation and thermal protection of the direction of the borehole at great depths are not provided. This disadvantage is due to the peculiarities of pipe insulation, which has low heat-insulating characteristics.

Known steel thermally insulated pipe according to the patent of Russia for utility model No. 62643, IPC E21B 17/00, publ. 04/27/2007, containing a steel pipe with a thermally insulating coating based on epoxy resins with the inclusion of glass microspheres in an amount of 60% of the volume and a thickness of 4 mm, and a protective layer in the form of a reflective screen made of aluminum foil is placed on the thermally insulating coating.

According to a utility model for manufacturing a structure, a thermally insulating coating is applied to a steel pipe and then a protective coating of aluminum foil.

The design disadvantage is high heat loss as a result of the inevitable damage to the reflective screen during transportation and installation.

Also known is the insulating direction according to the Russian patent for utility model No. 74415, IPC E21B 36/00, publ. 06/27/2008, adopted as a prototype and containing series-connected sections, each of which has coaxially located inner and outer pipes with a space between them filled with a heat-insulating layer, in the joint zone of the sections, the inner pipes protrude from the outer pipes and are connected together using a prefabricated collapsible connecting device made in the form of flanges. The junction zone of the sections is covered by a shell, while the cavity between the inner pipes and the shell is filled with thermal insulation.

According to this utility model, for the manufacture of thermally insulated pipes, a polyurethane foam (PUF) thermal insulation material is fed into the annular annular space formed by coaxially mounted inner and outer tubes in each section, while the protruding joints of the inner tubes are connected using flanges, and the outer tubes are covered with a shell, the cavity between internal pipes and a shell are filled with thermal insulation.

In practice, it is known that in the production of a long insulating layer, for example equal to the length of the outer pipes, in the process of supplying the insulating material (PPU) along the entire length and volume of the annular space between the inner and outer pipes, a large number of chemical reaction products of the PPU components are formed during foaming ( carbon dioxide, etc.) and air, which do not have time to completely be displaced from the annular space, due to the lack of constructive possibility of the rapid release of gases. This leads to incomplete and uneven filling of the annular space with thermally insulating material and the formation of large air cavities, which increases the thermal conductivity of the structure without providing optimal thermal insulation and reliable thermal protection of the borehole. In addition, with an uneven distribution of the insulating layer throughout the entire annulus, its physical and mechanical properties will be accordingly heterogeneous, which reduces the reliability and durability of the structure.

An object of the invention is to reduce the thermal conductivity of the structure by providing a complete and accordingly uniform filling of the annular space with thermally insulating material, which increases the reliability and durability of the structure.

The problem is solved as follows.

A method of manufacturing a thermally insulated casing string includes feeding a thermally insulating material into the annular annular space formed by coaxially installed inner and outer pipes in each section, protruding joints of the inner pipes are fixed with a collapsible connecting device, and the outer pipes are covered with a shell, the cavity between the inner pipes and the shell is filled with thermal insulation .

Unlike the prototype, before assembling the pipes in the wall of the upper and lower parts of the outer pipes of each section, through holes for the exit of gases are made and equipped with removable plugs for sealing.

The thermally insulated casing string contains series-connected sections, each of which has a coaxially located inner and outer pipe with a space between them filled with a heat-insulating layer, in the joint zone of the sections, the inner pipes protrude from the outer pipes and are connected using a collapsible connecting device, and the joint zone is covered by a shell, while the cavity between the inner pipes and the shell is filled with thermal insulation.

Unlike the prototype, in the wall of the upper and lower parts of the outer pipe of each section there are through holes for the exit of gases, equipped with removable plugs for sealing.

The presence of through openings for the exit of gases provides a complete exit of the excess products of the chemical reaction of the PPU components (during the manufacture of the insulating layer), which contributes to high-quality (full and uniform) filling of the annular space with insulating material without the formation of air cavities, which reduces the thermal conductivity of the structure, providing optimal thermal insulation and reliable thermal protection borehole. In addition, with a uniform distribution of the insulating layer, the uniformity of its physicomechanical properties throughout the entire annulus is ensured, which increases the reliability and durability of the structure. To ensure the integrity of the structure after the start of the release of polyurethane foam through the through holes, they are closed with removable plugs.

Thus, all the signs are significant and solve the problem.

The invention is presented in the drawing. The thermally insulated casing string contains sections connected in series, each of which has coaxially located inner 1 and outer 2 pipes, the space between which is filled with a thermally insulating layer 3 (polyurethane foam). In the joint zone of the sections, the inner pipes 1 protrude from the outer pipes 2 and are connected using a known collapsible connecting device, for example, a flange connection 4 or a sleeve (not shown), and the joint zone is overlapped by the shell 5. The cavity between the inner pipes 1 and the shell 5 is filled with known thermally insulating material 6, for example polyurethane foam. Through walls of the upper and lower parts of the outer pipe 2 of each section are made through holes 7 for the exit of gases, equipped with removable plugs for sealing (not shown). As plugs are used, for example, bolts, studs. Holes 7 are made, for example, by drilling.

A thermally insulated casing is made as follows. Before coaxial installation of pipes 1 and 2 in the wall of the upper and lower parts of the outer pipe 2 of each section, through holes 7 are drilled for the exit of gases. Polyurethane foam is fed into the annular space between the pipes 1 and 2 of each section and a heat-insulating layer 3 is obtained. The expandable polyurethane foam quickly displaces the gases and air formed in this process, which freely escape into openings 7, and the polyurethane foam freely fills the entire annular annular space. After the release of polyurethane foam through the openings 7, they are closed with removable plugs (not shown), which ensures the tightness of the structure. The protruding joints of the inner pipes 1 are fixed with a flange connection 4. The outer pipes 2 are covered with a shell 5, the cavity between the inner pipes and the shell is filled with thermal insulation 6.

Claims (2)

1. A method of manufacturing a thermally insulated casing string, comprising supplying thermally insulating material to the annular annular space formed by coaxially mounted inner and outer pipes in each section, protruding joints of the inner pipes are fixed with a collapsible connecting device, and the outer pipes are covered with a shell, the cavity between the inner pipes and the shell is filled with thermal insulation, characterized in that before assembling the pipes in the wall of the upper and lower parts of the outer pipe of each section Follow the important through holes for outlet of gases and provided with removable caps of sealing. 2. A thermally insulated casing string containing successively connected sections, each of which has a coaxially located inner and outer pipe with a space between them filled with a heat-insulating layer, in the joint zone of the sections, the inner pipes protrude from the outer pipes and are connected using a collapsible connecting pipe devices, and the joint zone is covered by a shell, while the cavity between the inner pipes and the shell is filled with thermal insulation, characterized in that in the wall of the upper and lower parts and the outer pipe of each section is made through holes for the exit of gases, equipped with removable plugs for sealing.

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