Straightness-keeping, deviation-preventing and speed-increasing drilling tool combination for sand shale interbedding area

Abstract

The utility model relates to the technical field of medium-deep layer geothermal drilling, and discloses a sand shale interbed area straightness-keeping deviation-preventing speed-increasing drilling tool assembly which comprises a PDC drill bit, a drill bit connector, a non-magnetic drill collar, a spiral drill collar, a spiral stabilizer, a common drill collar, an adapter substitute, a heavy weight drill rod and a common drill rod. The PDC drill bit, the drill bit connector, the non-magnetic drill collar, the spiral drill collar, the spiral stabilizer, the common drill collar, the adapter substitute, the heavy weight drill rod and the common drill rod are sequentially and fixedly connected together, and the rear end of the common drill rod is connected with a plurality of common drill rods of the same specification and size into a string. The contact area with the well wall in the drilling process is effectively reduced, the possibility of differential pressure retardation is greatly reduced, the phenomenon of sticking and drilling jamming is reduced, the real-time inclination measurement and straightness protection functions in the while-drilling process are achieved, and it is guaranteed that the well bore quality meets the requirement while the drilling speed is increased.

Description

Technical Field

[0001] This application belongs to the technical field of medium-deep geothermal drilling, and particularly relates to a straightness-preserving, deviation-preventing and speed-up drilling tool assembly in areas with interbedded sandstone and mudstone. Background Art

[0002] Medium-deep geothermal drilling refers to the process of extracting or exchanging geothermal resources by means of convective heat transfer or conductive heat transfer when the drilling depth is between 200m and 3000m and then utilizing them. There are significant characteristics in aspects such as material composition, bedding structure, sedimentary environment and physical property differences of the interbedded sandstone and mudstone. When conducting geothermal well drilling construction in areas with interbedded sandstone and mudstone, the following problems are likely to occur:

[0003] 1. The formation characteristics of the interbedded sandstone and mudstone are complex, and there are large differences in the hardness, strength, drillability, etc. of the rocks. The traditional drilling tool assembly cannot well adapt to this change, resulting in low drilling efficiency, serious wear of the drilling tools, and even possible damage;

[0004] 2. The formation structure of the interbedded sandstone and mudstone is loose, and the wellbore stability is poor, and phenomena such as collapse and caving are likely to occur. This requires that the drilling tool assembly must have good wellbore protection ability to prevent wellbore instability and ensure drilling safety;

[0005] 3. The formation of the interbedded sandstone and mudstone is complex and changeable, belonging to an easy-to-deviate formation. When drilling in this formation, the difficulty of hole deviation control increases with the increase of hole depth. If anti-deviation measures are not taken in advance, it is very likely that the drilling rig will tilt during the drilling process, thereby causing the well to deviate and the drilling quality not meeting the design requirements. Content of the Utility Model

[0006] The purpose of the present utility model is to solve the above problems, and a straightness-preserving, deviation-preventing and speed-up drilling tool assembly in areas with interbedded sandstone and mudstone is proposed.

[0007] In order to achieve the above purpose, the following technical solution is adopted in this application:

[0008] A straightness-preserving, deviation-preventing and speed-up drilling tool assembly in areas with interbedded sandstone and mudstone includes a PDC bit, a bit sub, a non-magnetic drill collar, a spiral drill collar, a spiral stabilizer, a regular drill collar, a crossover sub, a heavy drill pipe, and a regular drill pipe. One end of the bit sub is installed on the bit, and the PDC bit, bit sub, non-magnetic drill collar, spiral drill collar, spiral stabilizer, regular drill collar, crossover sub, heavy drill pipe, and regular drill pipe are fixedly connected in sequence. The rear end of the regular drill pipe is connected in series with several regular drill pipes of the same specification and size.

[0009] Preferably, the PDC bit, bit sub, non-magnetic drill collar, spiral drill collar, spiral stabilizer, regular drill collar, crossover sub, heavy drill pipe, and regular drill pipe are connected in sequence by threads.

[0010] Preferably, the pipe bodies of the bit sub, non-magnetic drill collar, spiral drill collar, spiral stabilizer, ordinary drill collar, adapter sub, heavy drill pipe and ordinary drill pipe are all cylindrical structures.

[0011] Preferably, the PDC bit comprises PDC composite bits, nozzles, matrix bodies, gauge materials, copper cores, weld seams, upper bodies and third external threads.

[0012] Preferably, the bit sub comprises a first pipe body and a third internal thread.

[0013] Preferably, the non-magnetic drill collar and the ordinary drill collar have the same structure, and both comprise a first drill collar external thread, a second pipe body and a first drill collar internal thread.

[0014] Preferably, the spiral drill collar comprises a second drill collar external thread, spiral grooves and a second drill collar internal thread.

[0015] Preferably, the spiral stabilizer comprises a first external thread, male sub, spiral structure, female sub and a first internal thread.

[0016] Preferably, the adapter sub comprises a second external thread, a third pipe body and a second internal thread.

[0017] Preferably, the heavy drill pipe and the ordinary drill pipe have the same structure, and both comprise drill pipe external threads, drill pipe male subs, drill pipe bodies, drill pipe female subs and drill pipe internal threads.

[0018] Compared with the prior art, the present application provides a straight hole maintaining, deviation preventing and ROP increasing drilling tool combination for interbedded sandstone and mudstone areas, and has the following beneficial effects:

[0019] The straight-hole maintaining, deviation preventing and ROP increasing drill string assembly in the sandstone-shale interbedded area determines a suitable drill string assembly by analyzing the formation conditions in the sandstone-shale interbedded area and combining with the characteristics of geothermal well drilling construction. The PDC bit can adapt to the formation hardness by adjusting the negative rake angle of the cutting teeth, thereby improving the mechanical drilling rate and service life of the bit. For the sandstone-shale interbedded formation, when the formation compressive strength is less than 10,000 psi and the shale component accounts for more than 40% of the total rock volume, the PDC bit has the best use effect. The non-magnetic drill collar is equipped with a wireless MWD inclinometer inside to monitor whether the borehole is drilled according to the designed trajectory. It is a drill string for detecting the borehole azimuth angle and accurate measurement. At the same time, due to its strong stiffness and good stability, it also plays a role in centralizing the bit and maintaining the wellbore trajectory. The outer surface of the spiral drill collar is processed with 3 right-handed spiral grooves, and its weight is reduced by 4% compared with the round drill collar of the same size. During drilling, the contact area with the wellbore is reduced, greatly reducing the possibility of differential pressure blockage, thereby reducing the occurrence of sticking and jamming, and facilitating the circulation of drilling fluid. The spiral stabilizer mainly plays a role of guiding and centralizing in the drill string assembly, can control the well deviation angle and wellbore curvature within the specified range, and make most of the weight of the drill collar concentrate on the bit, reducing the non-wellbore center forces and other external forces borne by the drill string and the bit. The ordinary drill collar has a smooth wall thickness, which is convenient for tripping while having a large gravity and stiffness, and can withstand large pressures and torques during drilling. The heavy drill pipe, as a transition section between the drill collar and the drill pipe, can reduce the fatigue failure of the drill string. Using a section of heavy drill pipe between the drill collar and the drill pipe can relieve the change of cross-section and stiffness, reducing stress concentration. The ordinary drill pipe has a simple structure. In addition to being easy to disassemble and assemble itself, it is also convenient and firm to connect with the lower heavy drill pipe and the upper kelly, which can effectively improve the drilling depth ability of the drilling rig. Description of the Drawings

[0020] Figure 1 FIG. is a schematic structural diagram of a straight-hole maintaining, deviation preventing and ROP increasing drill string assembly in the sandstone-shale interbedded area proposed by the present application;

[0021] Figure 2 FIG. is a schematic structural diagram of the PDC bit of a straight-hole maintaining, deviation preventing and ROP increasing drill string assembly in the sandstone-shale interbedded area proposed by the present application;

[0022] Figure 3 FIG. is a schematic structural diagram of the bit sub of a straight-hole maintaining, deviation preventing and ROP increasing drill string assembly in the sandstone-shale interbedded area proposed by the present application;

[0023] Figure 4 FIG. is a schematic structural diagram of the non-magnetic drill collar of a straight-hole maintaining, deviation preventing and ROP increasing drill string assembly in the sandstone-shale interbedded area proposed by the present application;

[0024] Figure 5 FIG. is a schematic structural diagram of the spiral drill collar of a straight-hole maintaining, deviation preventing and ROP increasing drill string assembly in the sandstone-shale interbedded area proposed by the present application;

[0025] Figure 6 This is a schematic structural diagram of the spiral stabilizer of a straight-hole maintaining, inclination-preventing and penetration rate-increasing drill string assembly proposed in this application for interbedded sandstone and mudstone areas;

[0026] Figure 7 This is a schematic structural diagram of the sub of a straight-hole maintaining, inclination-preventing and penetration rate-increasing drill string assembly proposed in this application for interbedded sandstone and mudstone areas;

[0027] Figure 8 This is a schematic structural diagram of the heavy drill pipe and the ordinary drill pipe of a straight-hole maintaining, inclination-preventing and penetration rate-increasing drill string assembly proposed in this application for interbedded sandstone and mudstone areas.

[0028] In the figure: A, PDC bit; B, bit sub; C, non-magnetic drill collar; D, spiral drill collar; E, spiral stabilizer; F, ordinary drill collar; G, sub; H, heavy drill pipe; I, ordinary drill pipe; 20, PDC composite button; 21, nozzle; 22, matrix; 23, gauge protection material; 24, copper core; 25, weld; 26, upper body; 27, third external thread; 30, first pipe body; 31, third internal thread; 40, first drill collar external thread; 41, second pipe body; 42, first drill collar internal thread; 50, second drill collar external thread; 51, spiral groove; 52, second drill collar internal thread; 60, first external thread; 61, male sub; 62, spiral structure; 63, female sub; 64, first internal thread; 70, second external thread; 71, third pipe body; 72, second internal thread; 80, drill pipe external thread; 81, drill pipe male sub; 82, drill pipe body; 83, drill pipe female sub; 84, drill pipe internal thread. Detailed implementation manners

[0029] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Embodiment 1

[0030] Refer to Figure 1-8 , a straight-hole maintaining, inclination-preventing and penetration rate-increasing drill string assembly for interbedded sandstone and mudstone areas, including a PDC bit A, a bit sub B, a non-magnetic drill collar C, a spiral drill collar D, a spiral stabilizer E, an ordinary drill collar F, a sub G, a heavy drill pipe H, and an ordinary drill pipe I. One end of the bit sub B is installed on the bit A, and the PDC bit A, the bit sub B, the non-magnetic drill collar C, the spiral drill collar D, the spiral stabilizer E, the ordinary drill collar F, the sub G, the heavy drill pipe H, and the ordinary drill pipe I are fixedly connected together in sequence. The rear end of the ordinary drill pipe I is connected in series with several ordinary drill pipes I of the same specification and size.

[0031] The PDC bit A, the bit sub B, the non-magnetic drill collar C, the spiral drill collar D, the spiral stabilizer E, the ordinary drill collar F, the adapter sub G, the heavy drill pipe H, and the ordinary drill pipe I are sequentially connected together by threads.

[0032] The PDC bit A is a PDC bit with a diameter of Φ241.3 mm. The outer diameter of the bit sub B is 163 mm. The outer diameter of the non-magnetic drill collar C is 163 mm. The outer diameter of the spiral drill collar D is 163 mm. The outer diameter of the spiral stabilizer E is 238 mm. The outer diameter of the ordinary drill collar F is 163 mm. The outer diameter of the adapter sub G is 163 mm. The outer diameter of the heavy drill pipe H is 127 mm. The outer diameter of the ordinary drill pipe I is 127 mm.

[0033] The pipe bodies of the bit sub B, the non-magnetic drill collar C, the spiral drill collar D, the spiral stabilizer E, the ordinary drill collar F, the adapter sub G, the heavy drill pipe H, and the ordinary drill pipe I are all cylindrical structures.

[0034] The PDC bit A includes PDC composite inserts 20, nozzles 21, matrix 22, gauge protection material 23, copper core 24, welds 25, upper body 26, and third external threads 27. The PDC bit A uses natural diamond cutters, which have high hardness and wear resistance. During drilling, it can quickly cut the formation and improve the drilling efficiency. The PDC composite inserts 20 are the cutting edges of the PDC bit A and can efficiently cut the formation. The main function of the nozzles 21 is to control the bottom hole flow pattern, reduce friction and resistance, assist in rock breaking, and clean the bottom hole cuttings. The main function of the matrix 22 is to weld the PDC composite inserts 20 on the reserved grooves of the matrix 22 to ensure the firm combination of the PDC composite inserts 20 and the matrix 22, improving the overall stability and durability of the bit. The gauge protection material 23 can increase the torque by increasing the contact area between the bit and the formation at the gauge section, helping to enhance the drilling ability of the bit. In addition, the overall stiffness of the bit can be increased by increasing the length of the gauge protection blocks, reducing the lateral offset. The main function of the copper core 24 is to dissipate heat, enhance the structural strength, and reduce the weight of the bit. The main function of the welds 25 is to connect the copper core 24 and the upper body 26. The main function of the upper body 26 is to bear and transmit the cutting force from the formation, and it also plays an active role in guiding and positioning. The main function of the third external threads 27 is to connect the bit sub B.

[0035] The bit sub B includes the first pipe body 30 and the third internal threads 31. The bit sub B is a key component connecting the PDC bit A and the non-magnetic drill collar C.

[0036] The non-magnetic drill collar C and the ordinary drill collar F have the same structure, both including the first drill collar external thread 40, the second pipe body 41 and the first drill collar internal thread 42. The non-magnetic drill collar C provides a non-magnetic environment for the internal wireless MWD inclinometer, which can monitor the drilling trajectory in real time during drilling, correct the deviation in time, reduce the well inclination, and the ordinary drill collar F has a relatively large stiffness. When used in combination with the spiral stabilizer E, a rigid drill string can be formed to prevent the lower drill string from bending during drilling, which helps to control the well inclination and ensure the straightness and accuracy of the borehole.

[0037] The spiral drill collar D includes the second drill collar external thread 50, the spiral groove 51 and the second drill collar internal thread 52. The spiral groove 51 enables the mud to flow freely around the drill collar, thereby balancing the pressure and preventing the formation of blockages. This characteristic effectively prevents the occurrence of differential sticking and improves the safety and efficiency of drilling.

[0038] The spiral stabilizer E includes the first external thread 60, the male sub 61, the spiral structure 62, the female sub 63 and the first internal thread 64. The spiral structure 62 is the key component for the spiral stabilizer E to play its role. During drilling, the spiral structure 62 realizes relative movement through its spiral geometry to maintain balance. This stability ensures the precise control of the wellbore trajectory and reduces the possibility of well inclination change.

[0039] The adapter sub G includes the second external thread 70, the third pipe body 71 and the second internal thread 72. The main function of the adapter sub G is to connect the ordinary drill collar F and the heavy drill pipe H.

[0040] The heavy drill pipe H and the ordinary drill pipe I have the same structure, both including the drill pipe external thread 80, the drill pipe male sub 81, the drill pipe body 82, the drill pipe female sub 83 and the drill pipe internal thread 84. The wall thickness of the heavy drill pipe H is increased by 2 - 3 times compared with that of the ordinary drill pipe I in terms of structure. As the transition section between the ordinary drill collar F and the ordinary drill pipe I, the heavy drill pipe H can effectively alleviate the changes in cross-section and stiffness, reduce stress concentration, and the ordinary drill pipe I, as the basic component of the drill string, mainly functions to transmit power and deepen the drilling depth. Embodiment 2

[0041] Refer to Figure 1-8 In this embodiment, the drill string assembly is specifically: 241.3mm PDC bit A × 0.35m + 165mm, bit sub B × 0.60m + 165mm, non-magnetic drill collar C × 9.42m + 165mm, spiral drill collar D × 9.10m + 238mm, spiral stabilizer E × 1.8m + 165mm, ordinary drill collar F × 9.10m × 8 pieces + 165mm, adapter sub G × 0.40m + 127mm, heavy drill pipe H × 9.3m + 127mm, ordinary drill pipe I × 9.70m × several pieces.

[0042] The operating principle of the present utility model is described as follows:

[0043] When this application is used, during the construction of geothermal well drilling in the sandstone-mudstone interbedded area, due to the complex formation characteristics and uneven structure of the sandstone-mudstone interbedded formation, as the drilling depth increases, the difficulty of controlling the drilling speed and hole deviation continuously increases. By optimizing each key component of the drill string combination, namely PDC bit A, non-magnetic drill collar C, spiral drill collar D, spiral stabilizer E, ordinary drill collar F, heavy drill pipe H, and ordinary drill pipe I, a drill string combination for straight hole protection and deviation prevention and speed increase in the sandstone-mudstone interbedded area is formed, realizing efficient drilling of medium-deep geothermal wells.

[0044] The above is only the preferred specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application, according to the technical solution of this application and its application concept, making equivalent replacements or changes should be covered within the protection scope of this application.

Claims

1. A drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone-mudstone interbedded areas, comprising a PDC drill bit (A), a drill bit joint (B), a non-magnetic drill collar (C), a spiral drill collar (D), a spiral stabilizer (E), an ordinary drill collar (F), a conversion joint (G), a weighted drill pipe (H), and an ordinary drill pipe (I), characterized in that: One end of the drill bit joint (B) is mounted on the drill bit (A); the PDC drill bit (A), the drill bit joint (B), the non-magnetic drill collar (C), the spiral drill collar (D), the spiral stabilizer (E), the ordinary drill collar (F), the conversion joint (G), the weighted drill rod (H), and the ordinary drill rod (I) are fixedly connected together in sequence; the rear end of the ordinary drill rod (I) is connected to a plurality of ordinary drill rods (I) of the same specification and size in a string.

2. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The PDC drill bit (A), drill bit joint (B), non-magnetic drill collar (C), spiral drill collar (D), spiral stabilizer (E), common drill collar (F), conversion joint (G), heavy-weight drill pipe (H), and common drill pipe (I) are sequentially connected together by threads.

3. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The drill bit joint (B), non-magnetic drill collar (C), spiral drill collar (D), spiral stabilizer (E), common drill collar (F), conversion joint (G), weighted drill pipe (H) and common drill pipe (I) all have cylindrical structures.

4. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The PDC drill bit (A) comprises a PDC composite sheet (20), a nozzle (21), a matrix (22), a gauge material (23), a copper core (24), a weld (25), an upper body (26), and a third external thread (27).

5. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The drill bit joint (B) comprises a first tube body (30) and a third internal thread (31).

6. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The non-magnetic drill collar (C) and the common drill collar (F) have the same structure, both comprising a first drill collar external thread (40), a second tube body (41) and a first drill collar internal thread (42).

7. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The spiral drill collar (D) comprises a second drill collar external thread (50), a spiral groove (51) and a second drill collar internal thread (52).

8. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The spiral stabilizer (E) comprises a first external thread (60), a male connector (61), a spiral structure (62), a female connector (63) and a first internal thread (64).

9. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1 is characterized in that: The conversion joint (G) comprises a second external thread (70), a third tube body (71) and a second internal thread (72).

10. The drilling tool assembly for maintaining straightness, preventing deflection and increasing speed in sandstone and mudstone interbedded areas according to claim 1, characterized in that: The weighted drill rod (H) and the ordinary drill rod (I) have the same structure, both comprising a drill rod external thread (80), a drill rod male joint (81), a drill rod body (82), a drill rod female joint (83) and a drill rod internal thread (84).

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