RU2269640C2 - Coupling to connect casing pipes or tubing strings in oil and gas wells - Google Patents

Abstract

FIELD: mining, particularly coupling means to connect casing pipes or tubing strings in oil and gas wells.

SUBSTANCE: coupling to connect pipes provided with tapered threads at ends thereof comprises clutch with cylindrical recess and elastic bush. Inner bush surface may cooperate with tapered thread run-out and with outer pipe surface. Outer bush surface may cooperate with cylindrical recess surface of the clutch. Metal ring is installed in joint at clutch end. The inner metal ring surface is provided with bead adapted to engage elastic bush arranged in the metal ring. Outer bush surface may cooperate with inner surface of metal ring after pipe and clutch screwing together. The bush is installed to provide cylindrical clutch groove filling.

EFFECT: prevention of sealing lubricant forcing-out, increased coupling protection against corrosive medium and electrochemical corrosion, increased reliability of well operation and reduced material consumption.

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Description

The invention relates to the field of mining, in particular to the oil and gas industry, and can be used to connect casing strings or tubing in oil and gas wells.

A compound is known that contains casing or tubing with threaded ends and couplings with cylindrical grooves [2], [3].

The disadvantages of the known compounds is the unreliability during operation in oil and gas wells due to leaks in the joints due to the presence of gaps in the threaded joints ([2], [3], through which a sealing lubricant is pressed out, which protects the connection from corrosion, at pressure drops between the columns during operation, which leads to depressurization of threaded connections, to the appearance of hydraulic flows, to filling gaps with pumped media, to an accelerated electrochemical process corrosion of threaded joints, to reduce the reliability of well operation, to unreasonable material costs associated with the elimination of leakage of columns and accidents in wells.

It is known the connection of casing strings or tubing with conical threads at the ends in oil and gas wells, containing a sleeve to the pipe with a cylindrical groove, an elastic sleeve [1].

The disadvantages of the known compounds are unreliability during operation in oil and gas wells due to leaks in the compounds, especially at high pressures MPa (kgf / cm ² ) -21 (210) and higher.

The objective of the invention is to prevent the extrusion of sealing lubricants that simultaneously protect threaded joints from nadira and corrosion through the gaps of threaded joints, to protect the joint from aggressive media, electrochemical corrosion processes, to increase the reliability of well operation, to reduce material costs associated with leakage of columns, in competitiveness of threaded joints of casing strings or tubing in oil and gas wells.

The solution to the technical problem is achieved by the fact that the connection of casing strings or tubing with tapered threads at the ends in oil and gas wells, containing a sleeve for pipes with cylindrical grooves and an elastic sleeve, the inner surface of which is made with the possibility of interaction with the run of the tapered thread and the outer the surface of the pipe, and the outer surface is configured to interact with the surface of the cylindrical undercut in the coupling, characterized in that in the connection at the end of the coupling is installed claimed a metal ring on the inner surface of which is formed a shoulder for interaction with an elastic sleeve placed in a metal ring, the outer surface of which is adapted to cooperate with the inner surface of the metal ring during screwing of the pipe and the sleeve, and the sleeve is arranged to fill the cylindrical recess of the coupling.

Figure 1 shows the coupling, at the end of which is installed a metal ring with an elastic sleeve.

Figure 2 shows the connection of the coupling with the casing or tubing passing through a metal ring with an elastic sleeve.

The connection of casing strings or tubing in oil and gas wells contains:

coupling - 1,

coupling end face - 2,

a metal ring - 3,

the inner surface of the metal ring is 4,

bead - 5,

elastic sleeve - 6,

the inner surface of the elastic sleeve - 7 (before screwing the pipe with the coupling, figure 1),

the run of the tapered thread of the casing or tubing - 8,

the outer surface of the casing or tubing - 9,

casing or tubing - 10,

the outer surface of the elastic sleeve - 11 (before screwing the pipe with the coupling, figure 1),

the outer surface of the elastic sleeve - 12 (after screwing the pipe with the sleeve, figure 2),

a cylindrical groove in the coupling - 13,

the inner surface of the elastic sleeve - 14 (after screwing the pipe with the sleeve, figure 2).

In a static position, the elements of the connection of the casing or tubing interact as follows.

On the end face 2 of the casing string 1 or tubing 10, for example, at the wellhead, a metal ring 3 with an elastic sleeve 6, which is bounded by a shoulder 5 and pre-centered by a cylindrical recess 13 relative to the axis of the sleeve 1 (Figs. 1, 2), is installed.

With a lifting mechanism, the casing or tubing 10 is installed through the inner surface 7 of the elastic sleeve 6 into the sleeve 1.

At the same time, it is necessary to apply a sealing lubricant to the threaded surfaces of the coupling 1 and pipe 10, which simultaneously protects the threaded connection from nadira and corrosion in accordance with GOST 632-80 or GOST 633-80 p.20. [2], [3].

Using a mechanical key, the pipe 10 is screwed into the sleeve 1.

At the same time, the torque when making up the threads should not exceed the values provided, for example, TU-26-02-652-75 or the developed technological regulations at the enterprise.

In the process of screwing the pipe 10 with the sleeve 1, the elastic sleeve 6 is screwed onto the tapered thread and its inner surface 7 (Fig. 1), grasping the run of the tapered thread 8 and the outer surface of the pipe 9, is deformed and changes shape according to the inner surface 14 of the elastic sleeve 6 (Fig. .2).

In turn, at the same time, as a result of deformation of the elastic sleeve 6, its outer surface 11 (Fig. 1) takes the form of a surface 12 (Fig. 2) in accordance with the inner surface of the metal ring 4 (Fig. 1), as well as in accordance with the surface cylindrical recess 13 in the coupling 1.

That is, after screwing the pipe 10 and the sleeve 1, the outer surface of the elastic sleeve 12 corresponds to the inner surface of the metal ring 4, filling the cylindrical recess 13 in the sleeve 1, and the inner surface of the elastic sleeve 14 corresponds to the run-off surface of the tapered thread 8 and the outer surface of the pipe 9.

In a dynamic position in an oil and gas or injection well with pressure drops in the annulus (between the tubing and production string elevator), the deformed elastic sleeve 6 is bounded on one side by the inner surface of the metal ring 4 and the cylindrical recess 13 in the sleeve 1, and on the other side of the run of the tapered thread of the pipe 8 and the outer surface of the pipe 9, eliminates the extrusion of lubricant through the gaps of the threaded joints and forcing into the gaps of the connections of the pumped aggressive environment, protects the connection in the well from processes of electrochemical corrosion, prevents depressurization of the threaded joints of the columns during operation.

The proposed new technical solution for connecting casing strings or tubing in oil and gas wells differs from the known technical solutions in terms of novelty; it is convenient when screwing and unscrewing pipes with couplings, for example, at the wellhead, is technologically advanced to manufacture, reliable in operation, competitive and use in production will provide a technical and economic effect.

Information sources

[1] US 4,706,997 A1, 1987.

[2] GOST 632-80. Casing pipes and couplings to them.

[3] GOST 633-80. Tubing and coupling to them.

Claims (1)

The connection of casing strings or tubing with conical threads at the ends in oil and gas wells, comprising a sleeve for pipes with a cylindrical groove and an elastic sleeve, the inner surface of which is designed to interact with the run of the tapered thread and the outer surface of the pipe, and the outer surface is made with the possibility of interaction with the surface of the cylindrical undercut in the coupling, characterized in that a metal ring is installed in the connection at the end of the coupling, on the inner surface In particular, a bead is made for interacting with an elastic sleeve located in the metal ring, the outer surface of which is made to interact with the inner surface of the metal ring when screwing the pipe and sleeve, and the sleeve is installed with the ability to fill the cylindrical undercut of the sleeve.

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