RU2735053C2 - Threaded connection of pipes (versions), connected pipe and adapter - Google Patents

Abstract

FIELD: drilling of wells.

SUBSTANCE: invention relates to devices for drilling wells for oil and gas production, in particular, to universal connections of drilling pipes to a string. Threaded connection of pipes consists of coupling and nipple parts connected by thread, at that threaded surfaces of parts are equally strong due to that on threaded surfaces there is hardening with passes, note here that hardened surface hardness makes from 380 to 620 Brinell hardness. Another version of threaded connection is described. Described is a connecting pipe as an element of a threaded joint, comprising a pipe body, at least one coupling or nipple attached end, on which there is a thread, and on the threaded surface and on the pipe end face there is hardening with passes, and hardness of the surface hardened layer is from 380 to 620 Brinell hardness. Adapter as element of threaded connection represents a branch pipe, on ends of which there is external or internal thread, wherein surface of thread is hardened, note here that reinforcing is performed on thrust ends of reducer. Note here that hardness of surface hardened layer of threaded surfaces and thrust faces of reducer makes 380–620 Brinell hardness.

EFFECT: technical result consists in hardening of threaded surfaces of connection.

4 cl, 6 dwg

Description

FIELD OF TECHNOLOGY

The claimed group of technical solutions relates to devices for drilling wells for oil and gas production, in particular, to universal joints of drill pipes in a string. It can be used when drilling wells for oil, gas, water and when extracting them from wells, during repair and maintenance of wells, as well as when performing other technological operations on a well, providing an increase in the service life of the connection, long-term safety from abrasion, deformation and corrosion of threaded surfaces of all elements of the connection, as well as the tightness of threaded connections with a large number of make-up and unscrewing cycles of the connection in the process of running the pipe string.

PRIOR ART

It is known that drill pipes are interconnected by means of drill joints with a special tool joint thread, and the ends of the pipes are hardened to increase the service life. When drilling wells, due to the large weight, for example, in 180 tons of drill string 3000 meters long, significant loads arise in the threaded connection. Breakdowns of a drill string are not uncommon; it takes about 1 million rubles or more to eliminate the consequences of one break. Drill pipes are used: for lowering into a borehole and lifting rock cutting tools; rotation transmission; creating an axial load on the tool; supply of flushing fluid or compressed air to the bottom. In addition, there are three types of drilling: vertical drilling, directional drilling and horizontal drilling.

A distinctive feature of the operation of such pipes is the effect of large bending, twisting, compressive and tensile loads on the pipes and their joints, in addition, the column is periodically assembled and disassembled. Pipes connected into a drill string are lowered to a depth of 3000 m or more, this requires about 300 pipes and, accordingly, to make one pipe string, 600 threaded ends must be cut, including outer (nipple) and inner (sleeve) ends. Traditionally, for connecting products for oil and gas purposes, a tapered tool joint thread is used according to GOST R 50864-96.

Drill string studies show that pipe failure is mainly due to variable loads that lead to thread breakage and failure. And since the main connecting element in the drill string is the thread, it is first of all necessary to improve the performance properties of the threaded connection. Thus, there is a problem of low reliability of threaded connections of drill pipes.

Let us consider technical solutions aimed at improving the operational characteristics of the threaded joint of drill pipes, as well as its individual elements: the attached pipe and the sub.

Known connection of pipes, including installed on the threaded end of one of the pipes to be connected, a connecting cylindrical coupling having an internal threaded surface, and a hollow cylindrical adapter made at one end with an internal thread, and at the other end with an external thread to interact with the thread of the end section of the other the pipe to be connected and the coupling thread, respectively. In this case, the coupling and the adapter are made of material of the same strength category as the pipes to be connected. This corresponds to the requirements of clause 2.5 of GOST 633-80 "Tubing pipes and couplings to them": "pipes and couplings must be made of steel of the same strength group." In addition, according to the same GOST 633-80, the thread of the coupling must have a zinc or phosphate coating. The coating method is not standardized by the standard, but at the time of its development, only electrolytic coatings with a thickness of the order of 10 microns were used, relatively soft and wear-resistant, designed to protect the thread from corrosion during storage and transportation of threaded elements. The method of hot-dip galvanizing by lowering the coupling into a bath with molten zinc is not used due to the unevenness of the coating thickness obtained on the thread and zinc deposits on the thread, which impede checking with gauges. Zinc electrolytic coating has low mechanical strength and is susceptible to hydrogen embrittlement in the aggressive environment of an oil or gas well. At present, all-Russian pipe factories use only phosphate coating of the thread of tubing couplings. Due to the above properties of coatings, the standard requirements for ensuring tightness of a threaded connection are based on the thickness of the most common phosphate coating of the coupling thread of the order of 10 μm.

The disadvantage of the known compound is its low durability. So, in the “Operating instructions for tubing” RD 39-136-95 in paragraph 7.15 it says: “When operating tubing, it is necessary to keep records of the number of make-up cycles - unscrewing threaded connections. The performance of threaded connections, according to the research carried out, remains up to 6-8 cycles. "

From the prior art on threaded pipe connections, a solution is known for the utility model patent No. 14995 "Connection of tubing or drill pipes" published on September 10, 2009. The connection of tubing or drill pipes, includes a cylindrical coupling installed at the threaded end of one of the pipes to be connected, having an internal threaded surface, and a hollow cylindrical adapter made at one end with an internal thread, and at the other end with an external thread, for interaction with the thread of the end section of the other pipe to be connected and the thread of the coupling, respectively, characterized in that the total height of the cylindrical surfaces of the coupling and adapter is made in accordance with the size of the mechanism for mounting / dismantling the pipe string, while the body of the coupling and the body of the adapter are made volumetric hardened, and their threaded surfaces made with additional wear resistance.

The disadvantage of the known connection is that the implementation of all threaded surfaces of the coupling and the sub more wear-resistant than the attached end of the pipe, leads to the fact that when performing multiple operations of screwing and unscrewing connections during the runs and ascents of the pipe string, the destruction of unreinforced threaded surfaces of pipes, interacting with hardened threaded coupling and adapter surfaces. As a result, after repeated operations on installation and dismantling of the column, the tightness of threaded connections is broken.

The closest to the claimed technical solution "THREADED PIPE CONNECTION (VERSIONS)" is the decision on the utility model patent No. 102665 "CONNECTION OF PUMP AND COMPRESSOR OR DRILL PIPES", published on March 10, 2011. The execution of the thread surface on the adapter and the coupling interacting with each other, additionally hardened to give it additional wear resistance, makes it possible to exclude damage to the thread of the adapter and coupling, and thereby ensure guaranteed tightness of threaded connections after multiple operations of mounting and dismounting of connections during descending and ascending a pipe string , which ultimately increases the operational reliability of the proposed connection. And the implementation of the thread sections of the adapter and the coupling interacting with the pipes, with the same strength characteristics as the pipes, makes it possible to exclude the premature destruction of the pipe thread (which happened in the prototype). In addition, the presence on the remaining threaded surfaces of the coupling and adapter (threaded connection with pipes) a layer of anti-seize coating, in particular a layer of soft metal applied, for example, by gas-dynamic (kinematic) spraying, allows to ensure the necessary operational reliability of the connection with ensuring the tightness of threaded connections after multiple operations of assembly and disassembly of connections during lowering and lifting of the pipe string. Coating the rest of the coupling and adapter with an anti-corrosive layer prevents premature rusting.

We believe that the main disadvantage of the identified technical solution is that all connection elements are not of equal strength. The disadvantages of the known solution also include:

- the lack of hardening of the threaded surface of the connected pipe itself, which can entail plastic deformation of the thread profile under increased loads and, as a consequence, loss of tightness of the threaded connection;

- the presence of one extra technological connecting element, in the form of a separate adapter in the presence of a coupling, which increases the time spent on assembling and disassembling the pipe string, as well as on its maintenance and repair, taking into account the fact that such a connecting element is available on each pipe in the string.

According to the decisions related to the pipes to be connected, the "PIPE OF THE PUMP-COMPRESSOR OR DRILLING COLUMN, COUPLING AND ROD FOR CONNECTING THE PIPES OF THE PUMP-COMPRESSOR OR DRILLING COLUMN" according to the patent No. 3849 published in June 2004, published No. The tubing of the tubing or drill string, contains a coupling and an adapter, and on the threaded surfaces of the coupling and adapter, protective coatings are applied by thermal diffusion galvanizing, characterized in that the protective coating of the thread surfaces consists of two layers: zinc coating.

The disadvantages of the revealed useful model include the fact that the phosphate coating is fragile and easily abraded. The proposed coating provides protection of the connection elements from corrosion during storage and transportation, but the thickness of the coating is insufficient for reliable sealing of the connection and increasing its resource.

Known "PUMP-COMPRESSOR OR DRILLING COLUMN" according to the patent for a useful model No. 27664, published on February 10, 2003. A tubing or drill string pipe containing a coupling and an adapter on the threaded ends subjected to chemical-thermal treatment, characterized in that a diffusion powder zinc coating with a thickness of 25 ⁺⁵ _-10 microns is performed on the threaded surfaces of the coupling and the adapter.

The disadvantages of the identified technical solution include unevenness on the outer surface of the coating thread. Electrolytic zinc coating has low mechanical strength and is susceptible to hydrogen embrittlement in an aggressive environment of an oil or gas well.

According to the decisions related to adapters (adapters), a "COUPLING ADAPTER" was identified under the patent for utility model No. 93129, published on November 12, 2009. Coupling sub is designed to connect tubing or drill pipes during their installation into a string. The sub contains threaded end portions and a middle part with an outer surface, the diametral dimension d of which is less than the diametrical dimension D of the end portions. The outer surface of the middle part is made in the form of a surface of revolution with a convex curved generatrix. When installing the column, a central load is applied to the wedge gripper dies of the assembly-dismantling mechanism, which allows optimizing the distribution of the load on the wedge grip dies by eliminating edge pressure on the sub surface.

The disadvantage of the identified technical solution is the lack of hardening of the sub, which leads to a small number of make-up cycles - unscrewing threaded connections.

The closest thing to the claimed technical solution "TRANSLATOR" is the sub for utility model patent No. 128651, published on May 27, 2013. A sub, which is a branch pipe with a thread at the ends. The thread surface of the sub is made hardened with additional wear resistance by carbonitriding. The coating has high density, high corrosion resistance, high hardness and wear resistance, high elasticity.

The disadvantage of this sub is that the hardening of the sub by carbonitriding technology requires placing the entire sub in a special furnace, as a result of which difficulties arise in using this hardening method. In addition, there is a danger of reducing the mechanical properties of the material of the entire sub, which can render the sub completely unusable for its intended use.

DISCLOSURE OF THE INVENTION

The tasks to be solved by the claimed group of inventions are:

- increasing the operational reliability of the connection without using at all or in the presence of only one additional connecting element, ensuring the tightness of threaded connections at increased loads and a large number of make-up and unscrewing cycles of the connection during the running operations of the pipe string;

- reduction of increased wear of the outer surfaces of the pipes to be connected and the sub as a result of the impact on them of the surfaces of the assembly tool mating with them, which performs the functions of holding and rotating the connection parts during the installation, dismantling, operation, maintenance and repair of the pipe

strings, as well as under the action of friction against the walls of the well and the operation of the string during tripping operations;

- reduction of time and resource costs for assembly, disassembly, maintenance and repair of the pipe string.

The technical result of the claimed group of inventions consists in strengthening all threaded joint surfaces.

The claimed technical result is achieved due to the fact that:

According to the first embodiment, the threaded pipe joint consists of coupling and nipple parts connected by threads, while the threaded surfaces of the parts are equally strong, due to the fact that hardening with gaps is performed on the threaded surfaces, and the hardness of the surface hardened layer is from 380 to 620 Brinells.

According to another embodiment, the threaded pipe connection consists of:

- two coupling parts and one nipple sub, connected by a thread;

- or from two nipple parts and one sleeve sub, connected by a thread;

- or one sleeve and one nipple piece and one mixed sub, threaded,

moreover, the mating threaded surfaces of the parts are equally strong, due to the fact that hardening with gaps is performed on the threaded surfaces, and the hardness of the surface hardened layer is from 380 to 620 Brinells.

A mixed sub is a sub with an internal box thread at one end and an external nipple thread at the other end.

The attached pipe, as an element of the threaded connection, includes its own pipe body, at least one coupling or nipple attachment end, on which there is a thread, and on the threaded surface and on the stop end of the pipe, hardening with gaps is made, and the hardness of the surface hardened layer is from 380 to 620 Brinell.

The sub, as an element of a threaded connection, is a branch pipe, at the ends of which an external or internal thread is made, and the surface of the thread is made hardened, characterized in that hardening is made on the stop ends of the sub, and the hardness of the surface hardened layer of the threaded surfaces and the stop ends of the sub is from 380 to 620 Brinell.

These features are essential and are interconnected with the formation of a stable set of features sufficient to obtain the required technical result.

The analysis of the state of the art made it possible to establish that analogs characterized by a set of features identical to all features of the proposed technical solution are absent, which indicates the compliance of the proposed utility model with the “novelty” criterion of protectability.

The claimed technical solution is industrially applicable, since in its manufacture well-known technologies used for the manufacture of threaded ends of pipes are used and does not require the use of special technologies or special equipment.

BRIEF DESCRIPTION OF DRAWINGS

The claimed group of technical solutions is illustrated by drawings, where:

fig. 1 is a general view of a threaded pipe joint, including coupling and nipple parts;

fig. 2 is a general view of a threaded pipe joint, which includes two coupling parts and one nipple sub;

fig. 3 is a general view of a threaded pipe joint including two nipple parts and one sleeve sub;

fig. 4 is a general view of a threaded pipe joint including one coupling piece, one nipple piece and one mixed sub;

fig. 5 - General view of the attached tube;

fig. 6 is a general view of the sub.

As shown in FIG. 1 threaded pipe connection consists of coupling 1 and nipple 2 parts connected by thread, and the threaded surfaces 3 and 4 of the parts are equally strong, due to the fact that hardening is performed on the threaded surfaces, and the hardness of the hardened surface layer is from 380 to 620 Brinells.

As shown in FIG. 2 threaded pipe connections, consists of two coupling parts 5 and 6, one nipple sub 7, connected by threads, and the mating threaded surfaces of parts 8 and 9 are equally strong, due to the fact that hardening is performed on the threaded surfaces, and the hardness of the hardened surface layer is from 380 to 620 Brinell.

As shown in FIG. 3 threaded pipe connection, consists of two nipple parts 10 and 11, one coupling sub 12 connected by thread, and the mating threaded surfaces of parts 13, 14 and 15 are equal strength, due to the fact that hardening is performed on the threaded surfaces, and the hardness of the hardened surface layer ranges from 380 to 620 Brinell.

As shown in FIG. 4 threaded pipe connections, from one coupling 16 and one nipple 17 parts, and one mixed sub 18 connected by threads, and the mating threaded surfaces of parts 19, 20, 21 and 22 are equal strength, due to the fact that hardening is made on the threaded surfaces, and the hardness of the surface hardened layer is 380 to 620 Brinell.

As shown in FIG. 5 the attached pipe includes its own pipe body 23, at least one sleeve (not shown in the figure) or nipple 24 attached end, on which there is a thread 25, and on the threaded surface and on the stop end 26 of the pipe, strengthening is made, where the hardness of the surface the hardened layer ranges from 380 to 620 Brinells. Strengthening can be performed both on the entire threaded surface of the head of the pipe to be connected and the entire surface of the end, and with gaps in the threaded section of the pipe to be connected.

As shown in FIG. 6, the sub is a branch pipe 27, at the ends of which there is an external thread 28 or an internal thread 29, and the surface of the thread is made hardened, the stop ends 30 of the sub are hardened. The hardness of the surface hardened layer of the threaded surfaces 28 and 29 and the stop ends 30 of the sub is 380 to 620 Brinells. Strengthening can be performed both on all threaded surfaces and thrust ends, and with gaps in the threaded section.

EXAMPLES OF EXECUTION

The tests of the claimed group of technical solutions were carried out to assess the performance characteristics of the threaded pipe joint, the service life to failure of the drill pipe was estimated, based on the indicator of the number of make-up / unscrewing cycles. The criteria for failure of drill pipes in the framework of the tests were understood as:

- breakage of the threaded part of the pipe;

- thread wear more than 1/3 of the turn height;

- crushing of the threads;

- wear on the outer surface of the pipe end with an internal thread (wear on the outer surface of the welded end with an internal thread) more than 1.5 mm in diameter.

Experimental test conditions are shown in Table 1.

The main variable is hardness resulting from hardening, Brinelli hardness unit (HBW). Also, within the framework of the tests carried out, both equal-strength threaded connections and threaded connections with a high difference in hardness of the hardened surfaces (more than 20%) were considered. In the framework of the experiment, thermo-mechanical and laser methods of hardening the threaded surfaces of parts were used.

According to the results of the tests carried out, the preferred hardness of the hardened threaded surface was revealed, which varies in the range from 380 to 620 Brinells. With a large difference in hardness, the service life to failure of drill pipes can be significantly lower. Due to the fact that the parts of the threaded connection are unequal, the harder part quickly wears out the softer one.

This group of technical solutions does not limit the methods of applying hardening to a threaded connection. Any methods of hardening thread processing can be used, for example, combined methods of hardening; laser hardening, plasma hardening; thermal, thermo-mechanical and chemical-thermal methods of hardening; chemical deposition methods; electrolytic hardening methods.

Claims (7)

1. Threaded pipe joint, consisting of coupling and nipple parts connected by thread, characterized in that the threaded surfaces of the parts are equally strong due to the fact that hardening with gaps is made on the threaded surfaces, and the hardness of the hardened surface layer is from 380 to 620 Brinells. 2. Threaded pipe connection, consisting of: two coupling parts and one nipple sub, connected by a thread; or from two nipple parts and one sleeve sub, connected by a thread, or one sleeve, one nipple and one mixed sub, threaded, characterized in that the mating threaded surfaces of the parts are equally strong due to the fact that hardening with gaps is made on the threaded surfaces, and the hardness of the hardened surface layer is from 380 to 620 Brinells. 3. A connected pipe, including its own pipe body, at least one coupling or nipple connected end, on which there is a thread, characterized in that hardening with gaps is made on the threaded surface and on the stop end of the pipe, and the hardness of the surface hardened layer is from 380 up to 620 Brinells. 4. Sub, which is a branch pipe, at the ends of which an external or internal thread is made, and the surface of the thread is made hardened, characterized in that hardening is made on the stop ends of the sub, and the hardness of the surface hardened layer of the threaded surfaces and stop ends of the sub is from 380 to 620 Brinelli.

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