RU2728105C1 - Threaded locking conical connection of drilling pipes and method of increasing its carrying capacity and service life - Google Patents

Abstract

FIELD: mining; oil industry.SUBSTANCE: invention relates to products of oil machine building and can be used in drilling of deep oil and gas wells, including with horizontal sections of their shafts. Threaded locking conical drill pipe joint includes a nipple and coupling parts combined with a matching axis of rotation, the pipe nipple part has a section with an external conical thread of a triangular profile and a thrust end near the base of the larger cone, and smaller cone of nipple part is equipped with threadless extender, coupling part of pipe has thrust end and is made with mating internal conical thread and bore for extension of nipple part. Threadless nipple extender is conical, and in coupling part there is a mating counter-thread with coaxial bore congruent with threadless cone of nipple extension, and end faces of nipple and coupling parts of threaded connection are made with negative taper.EFFECT: technical result consists in increasing service life of threaded joint of drill pipes and bearing capacity of threaded connection in conditions of wells with complex spatial parameters, high sealing capacity of threaded joint.3 cl, 1 tbl, 7 dwg

Description

The proposed technical solution for a threaded joint conical connection of drill pipes and a method for increasing its bearing capacity and service life are united by a common inventive concept, and relates to petroleum engineering products. It can be used when drilling deep oil and gas wells, including those with horizontal sections of their wellbores. It is known that the drill pipe tool joint has been developed and used in the oil industry for ninety years and continues to be modernized to this day. This is due to the general development of petroleum engineering and the complication of tasks arising in the construction of oil and gas wells. In recent years, domestic State standards for threaded tool joints have been revised several times. For example, GOST 5286- (53) 75 [1]; GOST 28487-90 [2]; GOST R 50864-96 [3]. GOST 34438.2-18 [4]. Since 2020, GOST 28487-2018 [5] “Threaded thrust connections with tool-joint thread of drill string elements. General technical requirements ".

Threaded joint conical joints of drill pipes must perform a number of important functions, which are aimed at: - fast and reliable connection (screwing) of pipes to each other; - the ability, at high values of axial tensile and compressive loads, to transmit the calculated torques to drill pipes and rock cutting tools; - ensuring reliable sealing of pipes at high pressure of the flushing fluid. In the practice of drilling deep wells, it is believed that threaded tool joints remain the most vulnerable node in the drill string assembly. They perceive complex alternating bending and tensile loads and have a tendency (with repeated acts of screwing and unscrewing pipes) to wear of the thread profile, with a loss of sealing ability and mechanical strength, with an increase in the risk of their dismemberment and accident. In this regard, the task of increasing the bearing capacity indicators, reducing the risk of accidents and the service life of the threaded lock joint under complex cyclic loads is relevant and should be considered, taking into account the developed innovative technical and technological solutions.

Known conical locking threads according to GOST 28487-90 [2] "Conical locking threads for drill string elements" and according to GOST R 50864-96 [3], which provide technical requirements for the profile and size of threads, and requirements for locking threaded connections. Currently, according to the above standards, most of the domestic drill pipes are produced, equipped with threaded tool joints, the outer diameter of which extends to tool joints with a diameter of 35 to 279 mm. The main technical requirements of the GOST R 50864-96 standard coincide with the requirements of API 7 (American Petroleum Institute, USA). According to the above-mentioned GOSTs, the taper of threaded locking joints with a ratio of 1: 4 and 1: 6 is regulated; and also the pitch of the triangular profile threads: - 5 or 6 threads at a length of 25.4 mm (inch). The disadvantage of the known technical solutions is the global lag of products of the domestic oil engineering industry from the metric measurement system, including threaded connections, from the dominance of foreign standards with an inch measurement system. This ultimately hinders the development and use of domestic innovative technologies aimed at creating a threaded conical connection with improved performance characteristics, in particular, with an increased service life and bearing capacity in the metric system of measurements.

Known technical solution - "Hermetic threaded connection of oil field pipes", protected by patent RU 2310058 [6]. This threaded joint is recommended for use in tubing and casing pipes with a taper of 1:16, which, for technical and technological reasons, cannot be used for tool joints of drill pipes with a large taper (1: 4 or 1: 6). Known threaded connection for drill pipes according to the French patent SU No. 1131481 [7], in which to increase the strength of the connection, the thread is made with a run, ending near the thrust ends of the elements. A device for connecting drill pipes is known according to RU patent No. 2354799 [8], dated April 18, 2008, in which two ratchet half-couplings are made at the ends of the lock nipple and the coupling to transmit the axial force. These technical solutions complicate the manufacture and control of a threaded connection and do not contribute to an increase in its service life. Known sealed threaded connection of oil field pipes RU No. 2297512 [9], published 20.04.2007 Bull. No. 11. However, due to the small taper of the tapered thread (1:16) of the threaded connection under consideration, as well as the absence of end surfaces at the base of the large cone, it excludes its use as a tool joint for drill pipes.

According to the results of the conducted patent research, the closest technical solution disclosed in [10, 11] was revealed - a prototype. The disadvantages of the identified prototype are the increased requirements for the accuracy of manufacturing the geometric parameters of the thread and linear dimensions along the supporting surfaces of the nipple and coupling parts. The requirement for simultaneous two-bearing stressed contact of the pin and box parts requires their precise adjustment (± 0.1 mm [11]) and does not fully contribute to an increase in the service life of the tool joints due to the weakening and relaxation of stresses on the supporting surfaces during operation, and also makes it difficult to repair threaded parts in case of critical wear.

The task of the proposed technical solution is to increase the service life of the threaded tool joint of drill pipes and indicators of the bearing capacity of the threaded joint in the conditions of drilling wells with complex spatial parameters. Including when drilling sidetracks, horizontal and branched boreholes of deep oil and gas wells, during work on their overhaul, as well as increasing the competitiveness of products (lock threaded joints) of the domestic oil and gas engineering industry. Drilling wells, including intervals with a borehole change rate of more than 2 ° by 10 meters and using known solutions with threaded tool joints for drill pipes, does not fully ensure the required increase in deep well drilling rates.

The solution to this problem is achieved by the fact that the full-size threaded part of the nipple of a typical tool joint in accordance with GOST 28487 2018 [10] is increased by a threadless conical extension. In this case, the linear dimension of the extension is in the range from 0.55 to 0.65 of the length of its threaded part, and in the sleeve part of the tool joint, after the end of the threaded typical cutting, an internal conical bore (surface) is provided, congruent with the conical extension of the nipple part. The abutting support surfaces of the nipple and coupling parts are structurally made with the possibility of their step-by-step interaction during screwing. So, at the stage of screwing the threaded connection, 30 ° -45 ° before the "stop" position (the limiting fixed position of the nipple and coupling elements at a regulated torque), first the conical surface of the extension of the nipple part, with the conical surface of the coupling part, is introduced into the tense radial contact ... Then, at the next stage, with further rotation of the nipple part relative to the coupling part, a strained coverage (interference) of the threaded parts of the nipple and the coupling is created. And at the final stage of the screwing cycle of the threaded connection, with the creation of the calculated torque for each standard size of the threaded connection, the end surfaces of the nipple and the coupling are closed, providing an interference fit (tension) along their ends. According to the proposed technical solution, the end parts on the nipple and socket of the threaded connection are made with a negative taper. The value of the parameter of the angle of closing (A) is 2-3 times higher than the angle of friction between steel and steel. This complex technical solution is aimed at balancing the axial load along the threads in the direction of its normalization and eliminating the effect of uneven loading, proved by Professor N.E. Zhukovsky in 1902. At the same time, the effect of the concentration of internal stresses arising during bending loads in the threaded grooves of the nipple part used in the known solutions, as well as the technical requirements of the standard design, is minimized. In the proposed threaded conical connection, for drill pipes and increasing the sealing ability, an option is provided for equipping the conical extension with a groove with a ring placed in it.

The expected result when using the considered technical proposal is associated with the possibility of transferring increased torque to the drill pipes and the bottom hole assembly (BHA) under conditions of operation with alternating bending loads in deviated wells, increasing the sealing capacity of the threaded joint and increasing its service life.

The threaded joint conical connection of drill pipes according to the present technical proposal is shown in the accompanying description of the figures (Fig. 1-7) and includes the following highlighted for understanding the main structural elements: Fig. 1 shows a threaded joint conical connection of drill pipes in a screwed state; in fig. 2 shows a fragment of II parameters of a conical threaded connection; in fig. 3 shows (fragment I, highlighted in Fig. 1) a diagram of the nipple part of the threaded parameters of the conical threaded connection; in fig. 4 shows (fragment I highlighted in Fig. 1) the parameters of the coupling part of the conical threaded connection; in fig. 5 shows (fragment I, extracted from Fig. 1) a diagram of a threaded connection, with visualization of forces (reaction of forces) acting in the elements of a threaded conical connection after make-up with a controlled torque; in fig. 6 shows (for visualization) diagrams of torques from the friction forces of the nipple part of the lock in the coupling part at the final stage of screwing the threaded joint; in fig. 7 shows (for visualization) diagrams of the axial load distribution for the threaded part of the coupling after make-up with the nipple.

Threaded tool joint conical connection of drill pipes includes nipple 1 and coupling 2 parts, coaxially connected by a triangular thread (fragment II). The threaded part of the nipple 1 is equipped with a threadless conical extension with a sealing ring 3 on its outer surface, and the coupling part 2 has an internal conical bore congruent to the conical extension of the nipple 1. The nipple part 1 has an end surface (Tn), and the coupling part has a reciprocal end surface ( Tm), which are closed at an angle of 60 ° ... 75 ° to the main axis of rotation.

The work of a threaded tool joint of drill pipes consists in a preparatory operation for make-up, in which the inner and outer surfaces of the nipple 1 and coupling 2 parts are cleaned of contaminants (sand, metal shavings) with a stream of water or steam, and then a grease is applied. After aligning the nipple part of the pipe, as a movable element, with the fixed coupling part of the pipe at the wellhead, make-up is performed with a mechanical key. The angular speed (ω) during make-up is taken as ω = (3-6) s ^-1 , with the creation of a regulated torque (Mcr) set for each standard size of the tool joint. At the same time, in the sector (β, Fig. 6) - beyond 30 ° -45 ° (0.5 ... 0.8 mm before closing the thrust ends of the nipple and the coupling) to the "stop" position - (the limit fixed position of the nipple and coupling elements at a regulated torque) are sequentially introduced first into a stressed (radial) contact the tapered surfaces of the extension of the nipple and coupling parts with a reaction from the coupling part F ₂ (Fig. 5). This technical solution is aimed, first of all, at counteracting the influence of negative alternating bending moments during the operation of threaded connections in a wellbore with intense curvature; and also for balancing the axial load along the threads of the threaded joint. With further rotation of the nipple part 1 relative to the coupling part 2, a stressed coverage (interference) of the threaded parts of the nipple and the coupling is created (Fig. 5 shows the reaction R of the coupling 2), and at the final stage of the screwing cycle of the threaded connection, ensuring the calculated for each standard size of the threaded the torque connection Mcr (Fig. 6) close the end surfaces of the nipple Tn and the coupling Tm with end fit (tension - F ₁ Fig. 5).

As an example of the implementation of this technical solution, the Table below shows the dimensions comparable in the locking thread with the prototype - Z-86 according to [10], [11].

Sources of information:

1. GOST 5286- (53) 75 "Locks for drill pipes". Publishing house of standards. 1975;

2. GOST 28487-90 "Taper lock thread for drill string elements". Profile, dimensions. Profile;

3. GOST R 50864-96 "Conical locking thread for drill string elements". Profile, dimensions, technical requirements ".

4. GOST 34438.2-2018 "Drill pipes and other elements of drill strings in the oil and gas industry." Basic parameters and control of threaded connections. Basic technical requirements.

5. GOST 28487-2018 "Threaded connections with tool joint for drill string elements". General technical requirements.

6. Patent RU 2310058. Tight threaded connection of oil-field pipes. Bul. No. 31 2007.

7. Description to the patent SU No. 1131481 F16L 15/00, France. 1984.

8. Patent RU No. 2354799 dated 18.04.2008. A device for connecting drill pipes.

9. Patent RU No. 2297512 Е21В 17/04. Sealed threaded connection of oil field pipes. Date published 04/20/2007. Bul. No. 11.

10. Patent RU 2508491. Threaded connection of drill pipes., Bul. fig. No. 6, 2014.

11. Operation manual for drill pipes with welded tool joints TMK UP EXD. REP S 02-015-2015. Edition 2. TMK Premium Service LLC 2017.

12. GOST 27834-95 Welded tool joints for drill pipes. Technical conditions.

Threaded joint conical connection of drill pipes and a method for increasing its bearing capacity and service life

Explanations for drawings:

1 - nipple part of the lock connection;

2 - sleeve part of the lock connection;

3 - a sealing ring;

4 - curve of load distribution in the threaded coupling of the coupling from the reaction P2;

5 - curve of the load distribution in the threaded connection of the coupling from the reaction P1;

6 - the final curve of the load distribution in the threaded coupling of the coupling from the reaction of forces P1 and P2;

S - thread pitch;

h _pr - the height of the thread profile;

σ is the width of the thread protrusion area;

r ₁ - radius of conjugation of the tops of the thread profile;

r ₂ - radius of rounding of the root of the thread;

H is the length of the nipple part of the threaded connection with a conical extension;

T _n - end platform of the nipple part;

T _m - end platform of the coupling part;

α is the angular parameter of the end area of the nipple part;

β is the angular parameter of the generatrix of the conical surface of the nipple threaded part;

γ is the taper angle of the extension;

g - linear dimension from the end of the nipple to the main plane;

f - section of thread runaway;

r ₃ - radius of curvature of the end cavity;

r ₄ - radius of curvature of the end part of the nipple;

D _n - the value of the outer diameter of the nipple part of the lock;

h ₁ - area of nipple blunting;

h ₂ - the tapered part of the nipple extension;

h ₃ - the value of the total length of the extension cord;

h ₄ - the size of the belt for the cutter exit;

h ₅ - thread length to the main plane;

h ₆ - the total length of the thread of the nipple part;

h ₇ - the size of the nipple part from the end to the main plane of the sealing cone;

h ₈ - the size of the belt for the cutter exit;

h ₉ - total thread length;

h ₁₀ - the size of the belt for the cutter exit;

h ₁₁ - bore width;

h ₁₂ - the estimated length of the position of the main plane of the inner cone of the coupling;

h ₁₃ - the total length of the bore of the inner part of the coupling;

d ₁ - the outer diameter of the extension;

d ₂ - outer diameter of the extension neck;

d ₃ - outer diameter of the base of the small thread cone;

d ₄ - outer diameter of the base of the large thread cone;

d ₅ - outer diameter of the cone bore;

d ₆ - inner diameter of the coupling bore;

d ₇ - inner diameter of the thread of the small thread cone;

d ₈ - calculated inner diameter of the thread at the base of the thread cone;

d ₉ - inner diameter of the bore at the base of the coupling cone;

d _ext - inner diameter of the pin;

d _cp - average thread diameter in the main plane;

η - size of the chamfer of the beginning of thread cutting;

R - reaction of forces of the section of the threaded connection;

F ₁ - reaction of forces of the end face of the end face of the coupling part;

F ₂ - the reaction of forces on the conical section of the coupling part;

P ₁ ; P ₂ ; T ₂ ; K ₁ - components of the reaction of forces, decomposed along the axes;

ϕ - the central angle of the beginning of the radial contact of the nipple cone is extended with the conical bore by the coupling part;

ϕ ₁ - the central angle of the beginning of the radial contact of the threaded nipple with the internal tapered thread of the coupling;

ϕ ₂ - the central angle of the beginning of the end contact of the nipple with the end of the coupling;

M (F ₂ ) - the maximum value of the braking (torque) moment from the reaction of the coupling part from the contact of the conical extension;

M (R) is the maximum value of the braking (torque) moment from the reaction of the threaded section of the coupling of the part from contact with the thread of the nipple;

M (cr) - the maximum value of the torque from the reaction of the coupling part, at the moment when the relative rotation of the nipple and the coupling stops ("stop" position).

Claims (3)

1. Threaded joint conical connection of drill pipes, including the nipple and coupling parts combined with the coinciding axis of rotation, the nipple part of the pipe has a section with an external conical thread of a triangular profile and a stop end at the base of the larger cone, and the smaller cone of the nipple part is equipped with a threadless extension; the coupling part of the pipe has a stop end and is made with a reciprocal internal conical thread and a bore for the extension of the nipple part, characterized in that the threadless nipple extension is conical, and in the coupling part there is a reciprocal conical bore coaxial with the thread, congruent with the threadless cone, and the nipple extension the ends of the nipple and box parts of the threaded connection are made with a negative taper. 2. Threaded tool joint of drill pipes according to claim 1, characterized in that the length of the section of the threadless conical extension is from 0.55 to 0.65 of the length of the threaded sections, with a taper from 20 ° to 35 °, and an annular groove is provided on its surface , with a sealing ring placed in it, while the negative taper of the end surfaces of the nipple and the coupling are inclined to the axis of rotation at an angle of 105 ° to 120 °. 3. A method for increasing the bearing capacity and service life of a threaded joint conical connection of drill pipes, including the creation of an end fit of the nipple and coupling parts when a torque is applied to them during make-up to zero angular relative alignment, characterized in that 30 ° -45 ° to zero the alignments are introduced in stages, first the tapered surfaces of the extension of the nipple and tapered bore of the coupling are introduced into the tense radial contact, then 8 ° -10 ° before zero alignment, a tense radial interference is created on the threaded parts of the nipple and coupling, and at the final stage of the screwing cycle of the threaded connection, the end surfaces of the nipple are closed and clutches with interference at the rated torque for the given standard size.

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