New, improved TC86 thread profile for connecting a drill rod

Abstract

The invention relates to a new, improved male and female TC86 connector thread profile for a downhole drill string, which solves the problem of the BECO-6 connector thread profiles that are normally used being subjected to shearing or cutting in mining operations, with the associated problems of forced stoppages and high maintenance costs; wherein the TC86 thread profile is machined into the threaded connector of the drill string and into a box element having an internal thread formed thereon, with a first contact surface located on one side of the internal thread and a second contact surface located on the other side of the internal thread; and wherein the external thread of the drill string and the internal thread of the box element match and are configured to engage with one another.

Description

[0001] A NEW AND IMPROVED TC86 THREAD FOR DRILL ROD CONNECTION

[0002] Technical Field of the Invention

[0003] The present description relates to threads for drill rods and, more particularly, the invention relates to a new and improved TC86 thread for connecting a drill rod.

[0004] Background of the Invention

[0005] A thread is an axis around which a cylindrical helical path of different pitches is described.

[0006] During bottom-hole drilling by means of a drill rod connected by means of a threaded portion to a drill bit, whether simple or tricone, the threaded or threaded portion is subjected to great stresses or strains.

[0007] Types of threads for drill rod

[0008] Quick-connect thread: Used on quick-connect drill rods. This thread is used to quickly connect and disconnect drill rods during well drilling operations. These quick connections are essential to ensure efficient drilling with minimal downtime. Features of the quick-connect thread include:

[0009] - Two-part design, allowing for quick and secure connection of drill rods.

[0010] - No additional tools required, which reduces connection and disconnection time.

[0011] - High load capacity, making it resistant to vibrations and wear.

[0012] - Available in different types of connections, depending on the type of pipe and drilling equipment.

[0013] BECO-6 thread: coarse thread used mainly in drill pipes for drilling / mining / rock drilling, thread of the same height between threads, distance between threads and angle between threads, two threads per inch, 7.62 cm (3”) taper per foot.

[0014] API (American Petroleum Institute) thread: the most commonly used in the petroleum industry, tapered thread at a 60° angle, has a trapezoidal shape and is designed to provide a secure and resistant connection to tension and torsion, threads per inch from 4 to 8. The API thread is used in thin and medium wall drill pipes.

[0015] VAM thread: used in drill rods for the oil industry, developed by the French company Vallourec and Mannesmann, tapered thread at a 45° angle, has a trapezoidal shape and is designed to provide a secure connection resistant to tension and torsion, threads per inch from 4 to 8.

[0016] Buttress thread: a tapered thread at a 45° angle used on thick-walled drill rods. This thread has a higher load capacity and greater fatigue resistance than standard API threads. It is distinguished by its two-section profile: a long, thin thread at the bottom and a short, thick thread at the top. This feature allows for a strong and secure connection and provides excellent resistance to fatigue and fracture, making it ideal for the oil and gas industry.

[0017] Premium Thread: This thread is resistant to twisting, wear, and extreme conditions. It is a high-quality thread used in situations requiring a stronger connection than conventional API threads in the oil industry. It features a spiral thread design that provides greater metal-to-metal contact.

[0018] High-strength thread (HTP): Typically used in high-pressure or deep-well drilling applications, and suitable for both drill rods and casing, HTP is commonly used in high-pressure, high-temperature pipes where a strong and secure connection is required. It consists of an external thread at the end of the rod and an internal thread in the coupling. HTP is found in most drill rod components, casing, and couplings. This spun connection can withstand vibrations and mechanical stresses in challenging drilling environments, such as deepwater drilling or drilling in complex geological formations.

[0019] High Torque (HT) thread: This is a variation of API thread and is used in the drill string to provide greater strength and durability. It is useful in drilling applications requiring higher load capacity, allowing it to withstand very high stresses. It features a double-pitch design.

[0020] Examples of such threads are found, for instance, in Australian Patent Publication No. AU2016204912B2, which relates to drill string components having a thread that extends around a body. The leading end of the thread may have a configuration that resists binding and cross-threading. In particular, the leading end of the thread may include a flat surface perpendicular to the body. The leading end of the thread may provide an abrupt transition to the full thread depth, which helps to reduce or eliminate cross-threading. The leading end of the thread may be oriented at an angle to the axis of the drill string component.When mating male and female threads are structured similarly, the mating threads slide together along an interface at the thread start face and stretch to a fully engaged condition. The thread starts can have full circumference engagement without any sticking positions.

[0021] Another example can be found in Swedish patent No. SE535814C2 relating to a spinning device, threaded joint and drill string component for impact rock drilling.

[0022] An objective of the present invention is to further develop devices in drilling technology and to provide a device with a drill column component comprising a hinge thread, as well as a drill column component and a method in which drilling can thereby be carried out more economically.

[0023] Summary of the Invention

[0024] One objective of this description is to provide a new and improved TC86 thread for connecting drill rods, which addresses the problems with thread shearing in the threaded connections currently used at the Sierra Gorda Mining Company. These connections include the BECO-6 thread, which has been used for decades on drill rods but, based on field evidence, is not suitable for the current loads (lbf) used at the Sierra Gorda Mining Company.

[0025] The object of the description is achieved through the aspects characterized by what is set forth in the independent claims. Some modalities of the description are described in the dependent claims.

[0026] The features and characteristics, if any, described herein that are not within the scope of the independent claims should be construed as useful examples for understanding various aspects of the description. Some aspects of the description are defined by the independent claims.

[0027] Brief Description of the Figures

[0028] The description will then be described in greater detail by means of some modalities with reference to the accompanying figures, in which:

[0029] Figure 1 schematically illustrates, in a left-side elevation, a downhole drill, according to the present utility model;

[0030] Figure 2 schematically illustrates the raising of a drill string using the TC86 wire method, according to the present utility model.

[0031] Figure 3 schematically illustrates the raising of a drill string using the prior art BECO-6 wire method, in accordance with the present utility model.

[0032] Figure 4 schematically illustrates a detailed elevation of the spun portion of a drill string with the TC86 thread modality, according to the present utility model.

[0033] Figure 5 schematically illustrates a detailed elevation of the spun portion of a drill string using the prior art BECO-6 thread modality, in accordance with the present utility model.

[0034] Figure 6 schematically illustrates a cross-sectional and detailed view of the drill string screwed to the drill bit with the TC86 thread modality, according to the present utility model.

[0035] Figure 7 schematically illustrates a cross-sectional and detailed view of the drill string screwed to the drill bit using the prior art BECO-6 thread modality, in accordance with the present utility model.

[0036] Figure 8 schematically illustrates a detailed view of the flank angle of the TC86 thread modality, according to the present utility model.

[0037] Figure 9 schematically illustrates a detailed view of the flank angle of the BECO-6 thread modality of the prior art, according to the present utility model.

[0038] Figure 10 shows the spun end of a drill rod with the prior art system, i.e., with the spun end of the BECO-6 type, sheared, according to the present utility model.

[0039] Detailed Description of the Utility Model

[0040] The present description relates to a new improved TC86 thread (1) for the connection (2) of a drill rod (3).

[0041] The presence of deflections during the start of drilling work (tie-in) in the testing and evaluation of the TC86 (1) and BECO-6 (4) wires of the prior art, is explained by the high working load (5) applied on the drill string (3) used (110,000 Ibf) which is close to the limit buckling load of the bar (see Fig. 1).

[0042] Under the same operating conditions, the TC86 thread design (1) exhibits lower magnitude stresses compared to the BECO-6 thread (4), which indicates that the TC86 thread design (1) presents better performance when bending loads are applied (6).

[0043] Both the drill string (3) and the threads of the collars (7) and connecting thread (8) of the drill bit (9) are subjected to tensile stress, permissible overstress, bursting, collapse, torsion and buckling.

[0044] The results from the life estimation test, in number of cycles, for each component show that in the case of the male threads (10), fatigue occurs in the first threads (11). Additionally, the results show that the TC86 thread design (1) would withstand at least six times more cycles of use than the prior art BECO-6 thread (4), under the load conditions analyzed in the test.

[0045] Figure 1 schematically illustrates a downhole drilling rig (12) viewed from the left side elevation (Ll). A downhole drilling rig (12) may comprise a drill rod (3), i.e., the tool that performs the thrust for the downhole drilling (13) carried out by an individual or tricone bit (9), attached to the drill rod (3) by means of a spun connecting portion (14), which is subjected to constant stresses, percussion, bending and buckling, which damage the spun connecting portion (14) until it shears.

[0046] The drill rods (3) used are 235 mm (9 1 / 4”) in diameter and 38.1 mm (1.5”) thick, with an effective length of 10,668 mm (35’) for both the improved TC86 (1) wire and the prior art BECO-6 (4) wire. The complete drill rod (3) consists of two 10,668 mm (35’) rods (3) (15) joined together, resulting in a rod with a total length of 21,336 mm (70’) (16). They are configured with TC86 (1) and BECO-6 (4) spun terminals according to Figures 1, 2, and 3.

[0047] In Figures 2 and 3, the elevations of the drill strings (3) with TC86 terminal (1) and with BECO-6 terminal (4) can be seen, and the AA section schematically illustrates the diameter (28) of the drill string (3) 235 mm (9 1 / 4”) and thickness (29) 38.1 mm (1.5”) of the drill string (3) tube wall.

[0048] Figures 4 and 5 show the characteristic dimensions of the TC86 (1) and BECO-6 (4) yarns, respectively. Due to the tapered design of the yarn (H), two diameters are defined: the diameter at the root of the yarn (H) and at the end (HT). The figures also show the total length of the yarn (H), the taper (C), and the yarn pitch (P). The following formula is used for the taper (C) of the yarn (H):

[0049] s / £) - ch

[0050] C ™ ta!'” ' i

[0051]

[0052] \ 2 # ¿ /

[0053] The following formula is used for threading:

[0054]

[0055] Where:

[0056] C = taper

[0057] Ph = thread pitch

[0058] D = largest diameter

[0059] d = smaller diameter

[0060] Nh = number of threads

[0061] L = thread length

[0062] In Figure 4, a detailed elevation of the spun portion of a male (10) drill string (3) and the female (He) spun portion can be observed schematically with the TC86 wire modality (1). From the results obtained from the tests at the worksite, it was found that fatigue occurs in the first wires (11). The number of wires (26) for this modality is eight wires (H), and the number of wires (27) x 100 mm is six wires (H). Additionally, the root diameter (RA) of the wire (H) and the end diameter of the wire (RT) can be seen.

[0063] In Figure 5, a detailed elevation of the spun portion of a male (10) drill string (3) and the female spun portion (He) can be schematically observed with the BECO-6 wire modality (4) of the prior art where, as with the TC86 wire (1), fatigue occurs in the first wires (11). The number of wires (26) for this modality, which is nine wires (H), and the number of wires (27) x 100 mm, which is six wires (H), can be seen. Additionally, the root diameter (RA) of the wire (H) and the end diameter of the wire (RT) can be seen.

[0064] Figure 6 schematically illustrates a cross-sectional and detailed view of the drill string (3), the threaded portion (14) of the drill rod (3), screwed to the threaded portion (17) of the drill bit (9) using the TC86 thread (1) modality, both the male thread (10) and the female thread (He), where it is machined into a box element (CA) having an internal thread (RI) formed on it with a first contact surface located on one side of the internal thread (RI) and a second contact surface located on the other side of the internal thread (RI);

[0065] where the external thread (RE) of the drill string (3) and the internal thread (RI) of the box element (CA) correspond and are configured to mesh with each other.

[0066] Figure 7 schematically illustrates a cross-sectional and detailed view of the drill string (3), spun portion (14) of the drill rod (3), screwed to the spun portion (17) of the drill bit (9) using the prior art BECO-6 thread (4) modality, both male thread (10) and female thread (He), where it is machined into a box element (CA) having an internal thread (RI) formed on it with a first contact surface located on one side of the internal thread (RI) and a second contact surface located on the other side of the internal thread (RI);

[0067] where the external thread (RE) of the drill string (3) and the internal thread (RI) of the box element (CA) correspond and are configured to mesh with each other.

[0068] Figure 8 schematically illustrates a detailed view of the flank angle (18) of the TC86 wire modality (1), for this modality it is 77.9°, with a pitch distance (19) of 0.005 mm. Figure 9 schematically illustrates a detailed view of the flank angle (18) of the BECO-6 wire modality (4), for this modality it is 59.6°, with a pitch distance (19) of 0.004 mm.

[0069] Table 1 below shows a summary of the parameters for each thread (H), including the thread pitch distance (19) in mm and the taper (C).

[0070] TC86 BECO-6 Thread Male diameter (mm) 163.49 159.3 Male diameter (mm) 132.3 115.89 Male thread length (mm) 130.28 112.33 Taper 6.8 10.9 Number of threads 8 Thread pitch (threads x 100 mm) 6 Flank angle 77.9 59.6

[0071]

[0072] Table 2 shows a summary of the mechanical properties of the materials of the drill rods (3) and the threads (H).

[0073] Element Designation Limit Resistance Modulus Coefficient Exponent Coefficient Exponent Yield Tensile Elasticity Resistance mr. Ductility mr.

[0074] Sy, Mpa Sut, Mpa E, Gpa 5'fb E'f c íí3.0 >00 1825 ^,«80 1.28

[0075] Ptcí and 2 Ai: i 080 1,240 0.73

[0076]

[0077] Table 3 shows the moment calculation for Pa = 489,304 N (110,000 lbf, most unfavorable operation) in the range e = 0 to e = 250 mm. Eccentricity Centripetal Force Moment e, mm Fe, N Mo, N*mm

[0078] © 0 © 25 445 16975.877 5© 839 33,951.754 75 1334 50,927.632 10© 1.739 67,9©3.5©9 125 2.223 34,379.336 15© 2.668 101,355.263 175.3.112 115,331.141 30© 3.657 135,307.613 225 4.002 15:2,732.395 25© 4.448 169,758.772

[0079]

[0080] Table 4 shows the summary of the results and the comparative analysis of the main efforts obtained based on load segregation, in addition to the number of extra cycles that the TC86 yarn (1) can withstand compared to the BECO-6 yarn (4).

[0081] Effort Unit BECO-6 TC86 Fe TC86 %Diff %Diff Maximum Female Male Female Male Riff Female Compression MPa 120.76 81.4 84.5 11449 40% -30% Torsion MPa 22.8 21.1 13.18 2% -42% Straight MPa 450.14 -133.92 3145 231.28 -47% -30%

[0082]

[0083]

[0084] Combined MPa 509 5.15.7 397.2 274.19 -47% 22

[0085]

[0086] Useful Life Cycles 1896.2 2100 5694.6 16175 670% 200%

[0087]

[0088]

[0089]

[0090]

[0091] With regard to the maximum stresses of the male thread (M), BECO-6 (4) is only superior to the male thread (10) TC86 (1) when compressive loads (20) are present. The TC86 (1) thread is superior to the BECO-6 (4) thread when the applied loads are torsional (21) or bending moment (22). Additionally, when the loads are applied simultaneously, the maximum stresses are 47% lower in the TC86 (1) thread compared to the BECO-6 (4) thread.

[0092] Figure 10 shows the spun end of a drill rod (3) with the prior art system, i.e. with the spun end of the BECO-6 type (4), sheared (24).

[0093] From the analysis carried out for the drill rod (3) and the TC86 (1) and BECO-6 (4) threads, according to the results obtained it is concluded that:

[0094] - The presence of deflections (see Fig. 1) during the start of the bottom hole drilling work (13) is explained by the high working load (5) used (110,000 lbf) which is close to the buckling limit load of the drill rod (3). In this sense, it is observed that the working load (5) is sufficient to significantly amplify the manufacturing or assembly deviations present in the drill rod (3), requiring only about 12.5 mm (1 / 2”) of initial deviation to generate a final deviation at the center of the drill rod (3) of approximately 250 mm under a high working load (5).

[0095] - The stresses are characterized by means of finite element modeling. The stress concentration occurs in the first (11) male (M) threads and the last (23) female (He) threads for both the TC86 (1) and BECO-6 (4) threads, where, in general, the latter presents better performance (lower stresses) than the BECO6 (4) thread.

[0096] - In the BECO-6 (4) wire of the prior art, the stresses are concentrated only in the first male (M) wire (11), overloading this area (see Fig. 4). On the other hand, the TC86 (1) wire manages to distribute the stresses better, since the concentration does not occur only in the first male (M) wire (11), but rather in the first wires (11) of this assembly, that is, as a drill string (3) that includes the drill bit (9). External torsional loads are the least demanding, followed by compressive loads (20). Both loads generate similar magnitudes and stress distributions for the TC86 (1) and BECO-6 (4) wires. Bending loads (6) are those that generate the greatest stresses for the male (M) and female (He) components of both types of wire, TC86 (1) and BECO-6 (4).Under the same operating conditions, the design of the TC86 yarn (1) exhibits lower magnitude stresses compared to the BECO-6 yarn (4), which indicates that the design of the TC86 yarn (1) exhibits better performance when bending loads are applied (6) (see Fig. 1).

[0097] The results of the service life estimation, in number of cycles, for each component show that in the case of the male threads (M), fatigue occurs in the first threads (11). Additionally, the results show that the TC86 thread design (1) would withstand at least 6 times more cycles of use than the BECO-6 thread (4) under the previously analyzed load conditions.

[0098] Industrial Application

[0099] The present invention relates to a new and improved TC86 thread for connecting a drill rod, further developing drilling technology devices, and providing a device with a drill column component comprising a hinge thread. According to its application, it finds use in industry, particularly in the metalworking industry, mining industry, lathe industry for thread making, drilling machinery industry, drill bit manufacturing industry, CAD / CAM design industry, and engineering industry.

[0100] Reference list

[0101] C conicity

[0102] CA box element

[0103] CO collar

[0104] H thread

[0105] HT thread ending

[0106] He female

[0107] Hm male thread P thread pitch

[0108] RA thread root diameter

[0109] RI internal thread

[0110] RE external thread

[0111] RT diameter thread end

[0112] T-pipe diameter 235 mm

[0113] 1 TC86 thread

[0114] 2 drill rod connection

[0115] 3 drill string / bar

[0116] 4 thread BECO-6

[0117] 5 compressive workload

[0118] 6 bending or flexural load

[0119] 7th thread of the necklace

[0120] 8-wire connector

[0121] 9 drill bit

[0122] 10 male threads

[0123] First 11 threads

[0124] 12 drill

[0125] 13 bottom hole drilling

[0126] 14 portion spun drill bar 15 bar of 10.668 mm

[0127] 16 bar of 21.336 mm

[0128] 17. Spindle portion of drill bit 18. Flank angle

[0129] 19 step distance

[0130] 20 compressive loads

[0131] 21 torque load

[0132] 22 bending moment load

[0133] Last 23 threads

[0134] 24 shear / cutting

[0135] 25 taper angle, number of threads

[0136] number of threads per 100 mm

[0137] drill string diameter

[0138] drill string pipe wall thickness

Claims

CLAIMS 1. An improved TC86 type (1) male (10) and female (He) connecting wire (8) for a downhole drill string (3), which solves the problem of shearing or cutting (24) of the BECO-6 connecting wires (4) normally used in mining operations, with the well-known problems of forced shutdowns and high maintenance costs, CHARACTERIZED in that the TC86 wire (1) is machined into the spun male (M) and female (He) connector of the drill string (3); and It is machined into a box element (CA) having an internal thread (RI) formed thereon with a first contact surface located on one side of the internal thread (RI) and a second contact surface located on the other side of the internal thread (RI); where the external thread (RE) of the drill string (3) and the internal thread (RI) of the box element (CA) correspond and are configured to mesh with each other.

2. The improved TC86 (1) male (10) and female (He) connecting thread (8) for a downhole drill string (3) according to claim 1, CHARACTERIZED in that the drill rod / string (3) is formed by a pipe (T) of diameter 235 mm (9 1 / 4”) and 38.1 mm (1.5”) thickness with an effective length of 10,668 mm (35’), wherein the complete drill rod / string (3) consists of the joining of two 10,668 mm (35’) rods, thereby obtaining a drill rod (3) with a total length of 21,336 mm (70’) for both the improved TC86 (1) thread and the BECO-6 (4) thread of the prior art.

3. The improved TC86 (1) male (10) and female (He) connecting thread (8) for a downhole drill string (3), according to claim 2, CHARACTERIZED in that for the estimation of the useful life in number of cycles, according to the test carried out in the field, for each component it is observed that in the case of the male threads (M) fatigue occurs in the first threads (11) of this, additionally the results show that the design of the TC86 thread (1) would withstand at least six times more cycles of use than the BECO-6 thread (4) of the prior art.

4. The improved TC86 (1) male (10) and female (He) connecting thread (8) for a downhole drill string (3) according to claim 3, CHARACTERIZED in that both the drill string (3) and the threads of the collars (CO) and connecting thread (8) of a drill bit (9) are subjected to tensile stress, permissible overstress, bursting, collapse, torsion and buckling.

5. The improved TC86 (1) male (10) and female (He) connecting thread (8) for a downhole drill string (3) according to claim 4, CHARACTERIZED in that due to the taper characteristic of the thread design (H) two diameters are defined, these correspond to the diameter value at a root of the thread (RA) and at the end of the thread (HT).

6. The improved TC86 (1) male (10) and female (He) connecting thread (8) for a downhole drill string (3) according to claim 5, CHARACTERIZED in that for a taper (C) of the thread (H) the following formula is obtained: For one pitch (Ph) of the thread (H) the following formula is obtained: where: C = taper Ph = thread pitch D = largest diameter d = smaller diameter Nh = number of threads L = thread length 7. The improved TC86 (1) male (10) and female (He) connecting thread (8) for a downhole drill string (3) according to claim 6, CHARACTERIZED in that according to the test carried out on both a spun portion (14) of a male (M) drill string (3) and a spun portion (14) female (He) with the TC86 thread modality (1) and the BECO-6 thread modality (4) fatigue occurs in the first threads (11).

8. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3) according to claim 7, CHARACTERIZED in that a flank angle (18) for the TC86 thread modality (1), for this modality is 77.9°, with a pitch distance (19) of 0.005 mm.

9. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3) according to claim 8, CHARACTERIZED in that a flank angle (18) for the BECO-6 thread modality (4), for this modality is 59.6°, with a pitch distance (19) of 0.004 mm.

10. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3), according to claim 9, CHARACTERIZED in that a taper angle (25) for the TC86 thread (1) modality, for this modality, is 6.8°, with a pitch distance (19) of 0.005 mm.

11. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3), according to claim 10, CHARACTERIZED in that a taper angle (25) for the BECO-6 thread (4) modality, for this modality, is 10.9°, with a pitch distance (19) of 0.004 mm.

12. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3), according to claim 11, CHARACTERIZED in that the number of threads (26) for the TC86 thread modality (1), for this modality, is eight threads.

13. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3), according to claim 12, CHARACTERIZED in that the number of threads (26) for the BECO-6 thread modality (4), for this modality, is nine threads.

14. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3), according to claim 13, CHARACTERIZED in that the number of threads (27) x 100 mm for the TC86 thread modality (1), for this modality, is six threads.

15. The improved TC86 male (M) and female (He) connector thread (8) (1) for a downhole drill string (3), according to claim 14, CHARACTERIZED in that the number of threads (27) x 100 mm for the BECO-6 thread modality (4), for this modality, is eight threads.

16. The improved TC86 (1) male (M) and female (He) connecting wire (8) for a downhole drill string (3) according to claim 15, CHARACTERIZED in that with respect to the maximum stresses of the male (M) wire (H), BECO-6 (4) is only superior to the male (M) TC86 (1) wire (H) when compressive loads (20) are present, the TC86 (1) wire is superior to the BECO-6 (4) wire when the applied loads are torsional (21) or bending moment (22), additionally, when the loads are applied simultaneously, the maximum stresses are 47% lower in the TC86 (1) wire compared to the BECO-6 (4) wire.

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