RU2398153C1 - Sealed threaded connection of oil-field pipelines - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: sealed threaded connection of oil-field pipelines is formed with enveloped and enveloping pipes with buttress conic threads of 1:16 taper and profile angle from 12.5° to 13.5°. Profile of the buttress conic thread has a shape of a non-isosceles trapezium with a stop facet of a turn positioned at a big angle to load direction. Enveloped and enveloping pipes contact with their conic bearing surfaces correspondingly made on external and internal surfaces of pipes on the section between the conic thread and a pipe end and correspondingly between the conic thread and a pipe body in form of a conic bearing surface with taper 1:10 to the side of each pipe. Conic thrust surfaces are made correspondingly on the end of the enveloped pipe in form of conic thrust end surface with taper from 74.5° to 75.5° in the direction of the enveloped pipe and on internal surface of the enveloping pipe at the section of conic bearing surface transition to the pipe body in form of conic thrust surface of taper from 74.5° to 75.5° in the direction of the enveloping pipe. A cylinder boring parallel to axis of the said pipe is made on the enveloped pipe; while on the enveloping pipe there is made the cylinder boring parallel to axis of the said pipe. Cylinder borings create a cavity at assembly of the threaded connection; on one side the cavity is limited with the cylinder boring on the enveloped pipe, while on the other side it is limited with the cylinder boring on the enveloping pipe. Length of the cylinder borings are within specified intervals of dependence values.

EFFECT: raised pressure tightness of threaded connection of pipes and processability of its manufacture.

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Description

The invention relates to the field of threaded pipe joints and can be used in the construction of oil and gas wells. The most effective use of the present invention for use in high-tight threaded joints of casing, tubing and other types of pipes when arranging horizontal and deviated oil and gas wells operating in difficult geological conditions.

In modern conditions, there is an increase in the requirements for tightness of the threaded connection of casing pipes, associated with the constant complication of production conditions. Insufficient tightness of the threaded connection often leads to premature corrosion damage of the metal in the area of the threaded connection, leakage and, further, to the destruction of the columns. One way to increase the tightness of a threaded connection is to select the optimal ratio of the geometric parameters of the elements of the threaded connection.

The prior art knows a tight threaded connection of oilfield pipes, including male and female pipes with tapered threads and tapered abutment surfaces, the first contacting of which are respectively made on the outer surface of the end portion of the male pipe in the form of a conical surface with a taper towards the axis of this pipe and on the inner surface of the female pipe in the area between the tapered thread and the pipe body, and the second contacting surfaces are made with respectively, on the male pipe in the form of a conical end surface with a taper angle in the direction of the conical thread on this pipe and a mating end conical surface on the female pipe made in the transition area of the first conical surface of this pipe to its body (FR No. 2798716 A1, F16L 15/00 published on March 23, 2001).

A disadvantage of the known device is the lack of tightness of the threaded connection due to its design with a small taper angle of the support conical surfaces, which does not allow to obtain a predetermined amount of interference with small axial movements of the nipple, which increases the period from the first contact of the sealing surfaces to ensure a given interference.

From the prior art it is known the closest in combination of essential features and the technical result achieved, an airtight threaded connection of oilfield pipes formed by male and female pipes with persistent tapered threads with a taper of 1:16 and a profile angle of 12.5 ° to 13.5 °, the profile of the persistent tapered thread has the form of an isosceles trapezoid with a persistent face of the coil, located at a large angle to the direction of the load, the male and female pipes are in contact with each other supporting surfaces made respectively on the outer surface of the male pipe in the area between the conical thread and the pipe end in the form of a conical supporting surface with a taper of 1:10 towards this pipe and on the inner surface of the female pipe in the area between the conical thread and the pipe body in the form of a conical a supporting surface with a taper of 1:10 towards this pipe, and conical thrust surfaces made respectively at the end of the male pipe in the form of a conical thrust end Surfaces with a taper angle from 74.5 ° to 75.5 ° in the direction of the male pipe and on the inner surface of the female pipe at the transition section of the conical supporting surface to the pipe body in the form of a conical contact surface with a taper angle of 74.5 ° to 75.5 ° in the direction of the enclosing pipe / RU 2297512 C2 (Open Joint-Stock Company "Taganrog Metallurgical Plant"), 04/20/2007 /.

A disadvantage of the known device is the lack of tightness of the threaded connection and low manufacturability in the manufacture of sealing elements on female and male surfaces.

Insufficient tightness of the threaded connection is caused by injury to the conical part of the sealing element when assembling the threaded connection both at the factory during manufacture and during assembly of the casing during operation.

Low manufacturability in the manufacture of sealing elements on female and male surfaces is due to the difficulty of making a groove on the female surface and subsequent quality control, which, in turn, leads to a decrease in tightness in case of mismatch of the geometric parameters of the groove.

The basis of the present invention is the task of creating such a sealed threaded joint of oilfield pipes, the use of which would improve the tightness of the threaded joint and manufacturability by simplifying the design, which, in turn, eliminates the possibility of injury to the conical part of the sealing element at the time of assembly of the threaded joint in the manufacture or during operation when assembling casing strings.

The problem is solved in that in a sealed threaded connection of oilfield pipes formed by male and female pipes with persistent tapered threads with a taper of 1:16 and a profile angle of 12.5 ° to 13.5 °, while the profile of the persistent conical thread has the form of unequal trapezoid with a persistent face of the coil, located at a large angle to the direction of the load, the male and female pipes are in contact with each other by conical supporting surfaces, respectively made on the outer surface the male pipe in the section between the conical thread and the pipe end in the form of a conical supporting surface with a taper of 1:10 towards this pipe and on the inner surface of the female pipe in the section between the conical thread and the pipe body in the form of a conical supporting surface with a taper of 1:10 the side of this pipe, and conical thrust surfaces made respectively on the end of the male pipe in the form of a conical thrust end surface with a taper angle of 74.5 ° to 75.5 ° in the direction of the male pipe and on the inside the lower surface of the enclosing pipe at the transition section of the conical abutment surface to the pipe body in the form of a conical abutting surface with a taper angle of 74.5 ° to 75.5 ° in the direction of the enclosing pipe, according to the invention, a cylindrical bore is made on the male pipe parallel to the axis of the pipe, and a cylindrical bore is made on the female pipe parallel to the axis of the pipe, while the cylindrical bores are made in such a way that, when assembling the threaded connection, they form a cavity that torons is limited by a cylindrical bore on the male pipe, and on the other hand by a cylindrical bore on the female pipe, the length of the cylindrical bore on the male surface being in the range from

L _1.max = (L ₅ +1) - ((⌀F + 0.25) -⌀ C) × 0.1 + (L ₉ -1)

before

L _1.min = L ₅ - ((⌀F-0.15) -⌀C) × 0, l + (L ₉ +0.5),

and the length of the cylindrical bore on the enclosing pipe is in the range from

L _2.max = L ₃ - (((B-1.25) + ((⌀E-1.607) - (⌀A + 0.5)) × 0.0625)

before

L _2.min = (L ₃ -0.5) - (((B + 1.75) + ((⌀ E -1.533) - (⌀ A -0.25)) × 0.0625),

where L _1.max and L _1.min - the maximum and minimum lengths of the cylindrical bore on the male pipe;

L _2.max and L _2.min - the maximum and minimum lengths of the cylindrical bore on the enclosing pipe;

A is the diameter of the cylindrical bore in the enclosing pipe;

B is the distance from the end of the enclosing pipe to the main plane;

F is the diameter of the sealing bore in the male pipe;

C is the diameter of the conical part of the sealing element;

E is the average diameter of the conical thread in the main plane;

L ₃ is the distance from the end of the enclosing pipe to the end of the cylindrical bore;

L ₅ is the total length of the sealing element of the male pipe;

L ₉ - the distance from the end of the covered pipe to the measuring plane of the diameter of its sealing element.

Performing a tight threaded connection of oilfield pipes in such a way that a cylindrical bore parallel to the axis of the specified pipe is made on the male pipe, and a cylindrical bore parallel to the axis of the specified pipe is made on the female pipe, while the cylindrical bores are made so that they form a cavity when assembling the threaded connection which, on the one hand, is limited by a cylindrical bore on the male pipe, and on the other hand, by a cylindrical bore on the female pipe, what is the length of the cylindrical bore on the male and female pipes is determined by the above dependence, provides an increase in the tightness of the threaded joint and manufacturability by simplifying the design, which, in turn, eliminates the possibility of injury to the conical part of the sealing element at the time of assembly of the threaded joint during manufacture or during operation when assembling casing strings.

The invention is further explained in the detailed description of its implementation with reference to the drawings, which depict:

figure 1 - diagram of the elements of the male pipe;

figure 2 is a diagram of the elements of the enclosing pipe;

figure 3 is a diagram of the inventive sealed threaded connection of oil field pipes assembly (cut);

figure 4 - diagram of the profile of the trapezoidal thread.

The hermetic threaded connection of oilfield pipes (Figs. 1-4) is formed by male 1 (Fig. 1) and female 2 with persistent tapered threads 3 with a taper of 1:16 and a profile angle of 12.5 ° to 13.5 °. The profile of the thrust conical thread 3 has the form of an isosceles trapezoid with the support face of the turn 4 (figure 4), located at a large angle to the direction of the load.

The conical supporting surfaces contacting each other are made on the outer surface of the male pipe 1 (Fig. 1) in the area between the conical thread 3 and the pipe end 1 in the form of a conical supporting surface 5 with a taper of 1:10 towards this pipe and on the inner surface of the female pipe 2 in the area between the conical thread 3 and the body of the enclosing pipe 2 in the form of a conical supporting surface 6 with a taper of 1:10 towards this pipe.

The conical contact surfaces contacting each other are respectively made at the end of the male pipe 1 in the form of a conical contact end surface 7 with a taper angle of 74.5 ° to 75.5 ° in the direction of the female pipe 1 and on the inner surface of the female pipe 2 at the transition section of the support conical surface 6 to the body of the female pipe 2 in the form of a conical thrust surface 8 with a taper angle of 74.5 ° to 75.5 ° in the direction of the female pipe 2.

On the female pipe 1 and the female pipe 2, cylindrical bores 9 and 10 are made parallel to the axis of the pipe 1 and 2, which, when assembling the threaded joint, form a cavity 11, which on one side is bounded by a cylindrical bore 9 on the male pipe 1, and on the other hand, a cylindrical bore 10 on the female pipe 2.

The cylindrical bore 9 and the conical abutment surface 5 form a sealing element on the male pipe 1.

The cylindrical bore 10 and the conical abutment surface 6 form a sealing element on the enclosing pipe 2.

The length L _{1 of the} cylindrical bore 9 on the male pipe 1 is in the range from

L _1.max = (L ₅ + l) - ((⌀F + 0.25) -⌀C) × 0.1 + (L ₉ -1)

before

L _1.min = L ₅ - ((⌀F-0.15) -⌀C) × 0.1 + (L ₉ +0.5),

and the length L _{2 of the} cylindrical bore 10 on the enclosing pipe 2 is in the range from

L _2.max = L ₃ - (((B-1.25) + ((⌀ E -1.607) - (⌀ A +0.5)) × 0.0625)

before

L _2.min = (L ₃ -0.5) - (((B + 1.75) + ((⌀ E -1.533) - (⌀ A -0.25)) × 0.0625).

The diameter A of the cylindrical bore of the female pipe 2 depends on the diameter of the pipes to be connected and can range from 0.9 to 0.996 of the diameter of the pipes to be connected.

The distance B from the end of the enclosing pipe 2 to the main plane (not shown in the drawing) is determined in the range from 40 to 50 mm.

The diameter F of the cylindrical bore 9 in the male pipe depends on the diameter of the connected pipes and can be in the range from 0.9 to 0.996 diameter of the connected pipes.

The diameter C of the conical part of the sealing element of the male pipe 1 is determined at a distance L ₉ from the end formed by the conditional intersection of the conical thrust end surface 7 with the supporting surface 5.

The average diameter E of the tapered thread 3 in the main plane is determined at a distance B from the end of the female pipe 2.

The distance L ₃ from the end of the enclosing pipe 2 to the end of the cylindrical bore 10 may be in the range from 90 to 12 mm.

The total length L _{5 of the} sealing element of the male pipe 1 may be in the range from 8 to 20 mm.

The distance L ₉ from the end of the male pipe 1 to the measuring plane of diameter C of its sealing element is determined at a distance of 2.5-5.5 mm from the conditional end formed by the conditional intersection of the conical thrust end surface 7 with the conical supporting surface 5.

The female pipe 2 can be made both in the form of a pipe with a bell-shaped element (not shown in the drawing), and in the form of a sleeve.

The operation of the tight threaded connection of oilfield pipes is as follows.

When performing screwing operations, the connection is initially carried out by the interaction of male 1 and female 2 with a conical thread 3. During the screwing process, the conical supporting surface 5 of male pipe 1 is advanced along the conical supporting surface 6 of female pipe 2 with the simultaneous formation of cavity 11. Then, the conical supporting surface 6 interacts with a conical supporting surface 5, while due to the occurring diametrical deformations of these surfaces, a hollow tional node "metal to metal".

With the relative movement of the pipes 1 and 2, the force contact of the conical thrust end surface 7 of the male pipe 1 and the conical thrust end surface 8 of the female pipe occurs, as a result of which contact stresses arise on their surfaces, the magnitude of which should be in the region of elastic deformations. The level of contact stress, under all equal conditions, is determined by the value of the contacting areas of the conical thrust surfaces 7 and 8.

Conical thrust surfaces 7 and 8 are made in such a way that when they are subjected to axial forces arising from the screwing of threads, the transverse component of this force is directed to the axis of the joint. This eliminates the so-called "unfolding" phenomenon, i.e. lateral deformation with increasing diameter in the area of the thrust ends, which makes the connection less critical to exceeding the make-up torque and increases its operational reliability.

A tight seal may be screwed using a polymerizable lubricant that hardens after assembly of the threaded joint.

In addition, the execution on the male 1 and female 2 cylindrical bores 9 and 10 eliminates the influence of burrs that occur during thread cutting during removal of the thread forming tool at the thread run-off section, at the edges of its vertices, along its inner diameter on the female part, which protrude towards the connection axis and are an obstacle, disrupt engagement and affect the compaction mode.

Thus, when screwing a threaded connection, the sections of the thread exit are always located in the groove zone, which excludes the influence of the thread surface on the exit section and on the accuracy of the interaction of the surfaces of the male and female pipes.

The advantage of the inventive threaded connection in comparison with the known one is also an increase in the tightness of reliability, an increase in the strength of the joint during its assembly, disassembly and operation, as well as an increase in the degree of its control suitability, which will make it possible to use this pipe connection for both liquid and gaseous media.

The inventive sealed threaded connection of oilfield pipes can be manufactured in industrial production using standard equipment. The greatest economic effect from the use of the claimed utility model is achieved when it is used in casing pipes.

Claims (1)

A tight threaded connection of oilfield pipes formed by male (1) and female (2) pipes with persistent tapered threads (3) with a taper of 1:16 and a profile angle of 12.5 ° to 13.5 °, while the profile of the resistant conical thread ( 3) has the form of an isosceles trapezoid with a thrust face of the turn (4), located at a large angle to the direction of the load, the male (1) and female (2) pipes contact each other with conical supporting surfaces made respectively on the outer surface of the male pipe (1) in the section between the conical thread (3) and the pipe end (1) in the form of a conical supporting surface (5) with a taper of 1:10 towards this pipe and on the inner surface of the female pipe (2) in the section between the conical thread (3) and the body pipe (2) in the form of a conical abutment surface (6) with a taper of 1:10 towards this pipe, and conical thrust surfaces made respectively at the end of the male pipe (1) in the form of a conical abutting end surface (7) with a taper angle of 74 , 5 to 75.5 ° in the direction of the male pipe (1) and on the inside the surface of the enclosing pipe (2) at the transition section of the conical supporting surface (6) to the pipe body (2) in the form of a conical abutting surface (8) with a taper angle of 74.5 to 75.5 ° in the direction of the enclosing pipe (2), characterized the fact that on the male pipe (1) a cylindrical bore (9) is made parallel to the axis of the pipe (1), and on the female pipe (2) a cylindrical bore (10) is made parallel to the axis of the pipe (2), while the cylindrical bores (9 and 10) are designed so that when assembling a threaded connection t cavity (11), which on one side is bounded by a cylindrical bore (9) on the male pipe (1), and on the other hand by a cylindrical bore (10) on the female pipe (2), the length of the cylindrical bore (9) on the male surface ( 1) is in the range from
L _1.max = (L ₅ +1) - ((⌀F + 0.25) -⌀C) 0.1 + (L ₉ -1)
before
L _1.min = L ₅ - ((⌀F-0.15) -⌀C) 0.1 + (L ₉ +0.5),
and the length of the cylindrical bore (10) on the enclosing pipe (2) is in the range from
L _2.max = L ₃ - (((B-1,25) + ((⌀E-1,607) - (⌀A + 0,5)) · 0,0625),
before
L _2.min = (L ₃ -0.5) - (((B + 1.75) + ((⌀Е-1.533) - (⌀А-0.25)) · 0.0625),
where L _1.max and L _1.min are the maximum and minimum lengths of the cylindrical bore on the male pipe (1);
L _2.max and L _2.min - the maximum and minimum lengths of the cylindrical bore on the enclosing pipe (2);
A is the diameter of the cylindrical bore in the enclosing pipe (2);
B is the distance from the end of the enclosing pipe to the main plane;
F is the diameter of the sealing bore in the male pipe (1);
C is the diameter of the conical part of the sealing element;
E is the average diameter of the tapered thread (3) in the main plane;
L ₃ is the distance from the end of the enclosing pipe (2) to the end of the cylindrical bore (10);
L ₅ - the total length of the sealing element of the male pipe (1);
L ₉ is the distance from the end of the male pipe (1) to the measuring plane of the diameter of its sealing element.

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