A drill assembly for air-impacted directional drilling and its application

Abstract

This invention discloses a drill string assembly for air impact directional drilling, comprising an impact bit, a pneumatic impactor, an impact damping sub, an air distribution sub, an anti-vibration air screw, a bidirectional damping sub, a locking sub, a non-magnetic drill string, a conventional drill string, and a keyed sub. The impact bit, pneumatic impactor, and impact damping sub constitute an impact rock-breaking assembly; the air distribution sub, anti-vibration air screw, and bidirectional damping sub constitute a directional drilling assembly; and the locking sub, keyed sub, wireless measurement-while-drilling instrument, and non-magnetic drill string constitute a directional drilling assembly. This assembly enables impact rock breaking, changing the traditional rock-breaking method of directional drill bits, reducing rock breaking energy, decreasing drill bit wear, and improving drilling efficiency in hard rock. It allows for rapid directional drilling in complex, easily leaky formations and hard formations with poor drillability, effectively improving drilling efficiency in complex formations, ensuring borehole trajectory adjustment accuracy, significantly improving directional drilling efficiency, and contributing to the development of directional drilling technology.

Description

Technical Field

[0001] This invention belongs to the field of directional drilling technology, and relates to a drilling tool, specifically a drilling tool assembly for air impact directional drilling and its application. Background Technology

[0002] During drilling in complex formations, mud drilling faces serious leakage or even loss of flushing medium when encountering tectonic fractures, karst caves, and other formations. Gas drilling overcomes the problem of drilling through leakage formations. However, in directional drilling, pneumatic screw drills are required. Compared with conventional hydraulic screw drills, pneumatic screw drills have problems such as low output torque, short life, and low drilling efficiency in hard formations. They cannot meet the requirements of rock breaking by rotating directional drill bits in rock formations, thus limiting the application of gas directional drilling technology in directional drilling in complex formations.

[0003] Compared to existing directional drilling methods using composite or roller cone bits, impact drilling fundamentally changes the rock-breaking mechanism, reducing the rock-breaking effort by replacing grinding and shearing with volumetric rock breaking. This reduces drill bit wear and improves drilling efficiency in hard rock. Furthermore, impact drilling requires less axial pressure than cutting rock, effectively preventing borehole deviation and improving the smoothness of the directional drilling trajectory and construction efficiency. During impact drilling, low drill bit speed, low rock-cutting resistance, and low screw torque are required, effectively extending screw life.

[0004] During the rock-breaking process of the pneumatic impactor, the piston experiences significant impact acceleration as it moves upwards. This impact energy is transmitted upwards along the drill string in the form of stress waves, causing strong periodic vibrations. The alternating stress caused by these vibrations easily leads to fatigue damage in both the pneumatic screw drill string and the electromagnetic wave measurement-while-drilling (MWD) instrument. Therefore, current technology cannot solve the lifespan problem of these impacts on pneumatic screw drill strings and MWD instruments. Furthermore, when both the pneumatic screw and the pneumatic impactor operate simultaneously at the bottom of the hole, the required airflow differs significantly. The pneumatic screw requires a larger airflow, while the pneumatic impactor at the drill string tip requires a smaller flow. Excessive flow can lead to excessively high impact frequencies, causing damage to the impactor. These factors are key constraints hindering the widespread application of air-directed drilling in complex formations. Summary of the Invention

[0005] In view of the technical problems of low efficiency, short service life of air-directed drilling in complex formations, short life of air screws and wireless drilling measurement instruments, and inability to effectively utilize the advantages of impact rock breaking and air drilling, the purpose of this invention is to provide an air impact directional drilling tool combination.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A combined drilling tool for air impact directional drilling, characterized in that the drilling tool assembly comprises an impact drill bit, a pneumatic impactor, an impact damping sub, an air distribution sub, an anti-vibration air screw, a bidirectional damping sub, a locking sub, a keyway sub, a wireless measurement-while-drilling instrument, a non-magnetic drill string, and a conventional drill string; wherein:

[0008] The impact drill bit, pneumatic impactor, and impact damping short section constitute an impact rock breaking assembly. The impact drill bit is installed at the front end of the pneumatic impactor, and the rear end of the pneumatic impactor is fixedly connected to the impact damping short section. This assembly is used to improve rock breaking efficiency and drilling efficiency during drilling in complex formations. The pneumatic impactor is provided with high-frequency impact force by compressed air, which causes the impact rod of the pneumatic impactor to repeatedly impact the impact drill bit, thereby achieving high-frequency impact rock breaking by the impact drill bit.

[0009] During the rock breaking process, the impact damping section is used to buffer the impact of the pneumatic impactor on the drill string, thereby improving the service life and reliability of the drill string.

[0010] The air distribution splitter, the anti-vibration air screw, and the bidirectional damping splitter constitute a directional drilling tool assembly. The air distribution splitter is fixedly connected to the rotor of the anti-vibration air screw, and the rotor of the air screw is driven to rotate by compressed air.

[0011] The anti-vibration air screw includes a rotor, a screw, and an outer tube. There is a certain angle between the rotor and the screw outer tube. By changing the angle between the angles, the drilling trajectory of the drill string can be controlled.

[0012] The anti-vibration air screw and the bidirectional damping short section form a dual damping system to further reduce the vibration caused by the drilling string during operation and improve the service life of the drilling string.

[0013] The locking section, keyway section, wireless MWD instrument, and non-magnetic drill string constitute a directional drilling tool assembly. The locking section is fixedly installed at the front end of the wireless MWD instrument. The bidirectional shock-absorbing section is provided with a positioning slot. The locking section and the positioning slot cooperate to form the axial positioning and locking device of the wireless MWD instrument, preventing axial movement during drilling and affecting the directional accuracy. This axial positioning and locking device can realize emergency jamming. In the event of a stuck drill, the jamming can be urgently released, and the wireless MWD instrument can be retrieved using a retrieval tool.

[0014] According to the present invention, the impact damping short section comprises: a first inner tube shaft, a front end cover, a first sealing ring assembly, an outer tube, a sliding sleeve, a second sealing ring assembly, a retaining ring, a return spring, a rear end cover, and a second inner tube shaft, wherein:

[0015] The first inner tube shaft and the second inner tube shaft are fixedly connected by threads. Two retaining rings fix the sliding sleeve on the second inner tube shaft. The front end cover and the rear end cover are fixed to the outer tube by threads. The first inner tube shaft and the second inner tube shaft can slide axially.

[0016] Two sets of return springs are provided between the retaining ring and the front and rear covers to restrict the positions of the first inner tube shaft and the second inner tube shaft in the free state.

[0017] The first inner tube shaft is provided with a first damping air hole, and the second inner tube shaft is provided with a second damping air hole; a first sealing ring group is installed between the front end cover and the rear end cover and the first inner tube shaft and the second inner tube shaft, and a second sealing ring group is provided between the sliding sleeve and the outer tube; wherein, the first sealing ring group is used to realize the gas seal between the first inner tube shaft and the front end cover, and the second inner tube shaft and the rear end cover, and the second sealing ring group is used to realize the gas seal between the cavities of the two return springs;

[0018] When compressed air enters the cavity of the return spring between the first inner tube shaft and the second inner tube shaft and the outer tube through the first damping air hole and the second damping air hole, during impact drilling, the pneumatic impactor drives the first inner tube shaft and the second inner tube shaft to vibrate axially. During the vibration, the air flows through the first damping air hole and the second damping air hole between the inner shaft hole and the cavity of the return spring to form a damping force, thereby achieving the purpose of air vibration reduction. When the pneumatic impactor drives the first inner tube shaft and the second inner tube shaft to vibrate with a large amplitude, the first damping air hole is blocked by the front end cover or the second damping air hole is blocked by the rear end cover. At this time, the compressed air generates a large load resistance, thereby further reducing the impact force on the drill string. The compressed air can limit the excessive compression of the return spring by the cavities of the two return springs, and at the same time, non-contact vibration reduction is achieved through the compressed air.

[0019] Specifically, the air distribution and diversion section is used to divert compressed air, controlling the airflow to the air down-the-hole hammer within a set range and ensuring it does not change with load variations. Excess air is discharged into the annular space, which protects the pneumatic impactor, improves rock-breaking efficiency, reduces wear on the impact drill bit, and extends service life.

[0020] Specifically, the bidirectional damping short section includes: a joint, a first elastic body, a rod, a core tube, a second elastic body, and a cap, wherein:

[0021] The connector and the rod body are fixedly connected by threads, the plug is fixedly connected to the rod body by threads, a core tube is installed inside the rod body, the core tube can slide axially inside the rod body, a first elastic body and a second elastic body are provided between the connector and the core tube and between the plug and the core tube; there are two positioning grooves on the inner side of the core tube.

[0022] Specifically, the locking section includes: a seat shaft, retaining balls, a first support spring, a retaining sleeve, and a second support spring. The retaining sleeve is fitted onto the seat shaft and slides back and forth on it. Four retaining balls are installed in the retaining slot at the front end of the seat shaft. The first support spring is provided at the bottom of the retaining balls, and the second support spring is provided at the step portion between the retaining sleeve and the inner shaft. The retaining sleeve slides back and forth on the seat shaft to limit and release the retaining balls. When the retaining balls are released, the first support spring pushes the retaining balls to move out of the retaining slot.

[0023] Furthermore, the non-magnetic drill bit has an elastic support inside its tube wall. When the wireless drilling directional measuring instrument is lowered to the required position and locked, the elastic support stably supports the wireless drilling directional measuring instrument, thereby straightening the instrument and further reducing vibration to protect it and improve measurement accuracy.

[0024] The air impact directional drilling tool assembly of this invention can be used in impact directional drilling applications in complex, easily leaky formations and hard formations with poor drillability. By changing the rock-breaking method of the drive directional drill bit, the rock-breaking work is reduced, drill bit wear is decreased, and drilling efficiency in hard rock is improved. At the same time, impact rock breaking requires less axial pressure than cutting rock breaking, which can effectively prevent borehole deviation and improve the smoothness of the directional drilling trajectory and the efficiency of directional drilling construction. During impact rock breaking, the rock cutting resistance is small, and the low torque operation of the anti-vibration air screw can effectively improve the screw life. By setting vibration damping devices between the pneumatic impactor and the anti-vibration air screw, between the anti-vibration air screw and the wireless drilling rig, and in the non-magnetic drill bit, a multi-stage all-round vibration damping system is formed in conjunction with the anti-vibration air screw to improve the accuracy of directional drilling trajectory measurement and control, and also improve the reliability and service life of the drill string.

[0025] The air impact directional drilling tool assembly of this invention features a multi-stage damping system, effectively reducing the impact stress on the screw and instruments caused by high-frequency vibrations of the impactor. Through the design of a low-speed pneumatic screw and a compressed gas diversion device, it achieves the matching use of the pneumatic screw and the pneumatic down-the-hole hammer, thus developing a pneumatic impact directional drilling technology. This technology is beneficial for solving the directional drilling challenges in complex rock formations, especially those prone to leakage. This invention enables rapid pneumatic impact directional drilling in complex, easily leaky, and poorly drillable hard formations, effectively improving drilling efficiency in complex formations. Compared with existing technologies, it has the following technological innovations:

[0026] (1) Impact directional drilling was used to realize directional drilling in complex formations, which solved the problems of leakage and water shrinkage in complex formations. At the same time, it changed the traditional bolt-driven drill bit rotation cutting and rock breaking method and improved the rock breaking efficiency.

[0027] Air drilling can effectively avoid complex downhole conditions such as well leakage, provides good bottom cleaning and cooling conditions, extends the service life of drill bits, and is beneficial for drilling operations in complex formations.

[0028] (2) It solves the problem of low mechanical efficiency and difficulty in directional drilling when using rotary cutting to break rocks in traditional directional drilling construction.

[0029] In traditional air screw directional drilling, the screw output torque is small and the rotation speed is high. During the rotational rock breaking process, a large axial force is required to press the drill bit's rock breaking teeth into the rock. Taking advantage of the rock's low shear strength, rock breaking is achieved through shearing. When the axial pressure is insufficient or the drill bit speed is too high, the drill teeth cannot effectively press into the rock, resulting in surface breakage and fatigue breakage as the main processes. This leads to rapid drill bit wear and low rock breaking efficiency. This invention fully utilizes the large instantaneous impact of impact drilling, which primarily involves volumetric rock breaking. This reduces the rock breaking work, decreases drill bit wear, extends the drill bit replacement cycle, significantly improves the mechanical drilling speed, shortens the drilling cycle, and reduces drilling costs.

[0030] (3) It solves the technical problems of large axial force required for air screw and hydraulic screw to rotate and crush rock, easy deviation of the borehole, difficulty in controlling the trajectory in hard and complex conditions, and high cost.

[0031] Rotary cutting of rock requires a large axial force. During drilling, excessive axial force can easily cause the drill string to bend and become unstable, resulting in deviation of the drilling trajectory and the appearance of doglegs. Frequent corrections to the drilling trajectory are required during the drilling process, which increases the difficulty of directional drilling trajectory control and the drilling cycle and cost.

[0032] (4) The use of a multi-vibration damping system can effectively reduce the impact of high-frequency vibration of the impactor on the screw and instrument, and improve the service life of the air screw and wireless drilling gauging instrument.

[0033] (5) The gas distribution and diversion short section can realize the quantitative control of the airflow through the end air impactor, and the flow rate does not change with the load, which further improves the rock crushing efficiency and the service life of the impactor. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the drill string assembly structure for air impact directional drilling according to the present invention;

[0035] Figure 2 This is a schematic diagram of an impact damping short section structure;

[0036] Figure 3 This is a schematic diagram of the shock absorption process using a short section shock absorber.

[0037] Figure 4 This is a schematic diagram of a two-way damping short section structure;

[0038] Figure 5 This is a schematic diagram of the locking short section structure;

[0039] Figure 6 This is a schematic diagram of the locking and positioning of the short section;

[0040] Figure 7 This is a schematic diagram of a non-magnetic drill bit.

[0041] The markings in the diagram represent: 1. Impact drill bit, 2. Pneumatic impactor, 3. Impact damping sub, 4. Air distribution sub, 5. Anti-vibration air screw, 6. Bidirectional damping sub, 7. Locking sub, 8. Wireless drilling survey instrument, 9. Non-magnetic drill string, 10. Ordinary drill string, 11. Keyway sub.

[0042] 301, First inner tube shaft; 302, Front end cover; 303, First sealing ring assembly; 304, Outer tube; 305, Sliding sleeve; 306, Second sealing ring assembly; 307, Retaining ring; 308, Return spring; 309, Rear end cover; 310, Second inner tube shaft; 301a, First damping vent; 309a, Second damping vent;

[0043] 601, Connector; 602, First elastic body; 603, Rod; 604, Core tube; 605, Second elastic body; 606, Plug; 604a, Positioning slot.

[0044] 701, seat shaft; 702, retaining ball; 703, first support spring; 704, retaining sleeve; 705, second support spring; 701a, first air passage; 704a, second air passage.

[0045] 901. Pipe wall; 902. Elastic support;

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0047] The following are specific embodiments of the present invention. It should be noted that the following embodiments are preferred examples, and the present invention is not limited to the following embodiments. Any addition or equivalent transformation of technical features based on the technical solution of this application shall fall within the protection scope defined by the claims of the present invention.

[0048] In the following description, it should be noted that the terms "front," "rear," "left," and "right," etc., indicating the working position relationship of the drill bit, are based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to make it easier for those skilled in the art to understand the technical solution of the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] This embodiment provides a combined drill string for air impact directional drilling. The drill string assembly includes an impact bit 1, a pneumatic impactor 2, an impact damping sub 3, an air distribution sub 4, an anti-vibration air screw 5, a bidirectional damping sub 6, a locking sub 7, a wireless measurement-while-drilling instrument 8, a non-magnetic drill string 9, and 10 strings of ordinary drill strings; wherein:

[0050] The impact drill bit 1, pneumatic impactor 2, and impact damping sub 3 form an impact rock-breaking assembly to improve rock-breaking efficiency and drilling efficiency during drilling in complex formations. The pneumatic impactor 2 is driven by compressed air, and its impact rod repeatedly impacts the impact drill bit 1 to achieve high-frequency impact rock breaking.

[0051] The impact drill bit 1 is installed at the front end of the pneumatic impactor 2, and the rear end of the pneumatic impactor 2 is fixedly connected to the impact damping section 3. During the rock-breaking process, the impact rod of the pneumatic impactor 2 provides high-frequency impact force, which will cause high-frequency vibration of the drill string. The impact damping section 3 plays a buffering role to offset the vibration impact of the pneumatic impactor 2 on the drill string, thereby improving the service life and reliability of the drill string.

[0052] The gas distribution and diversion short section 4, the anti-vibration air screw 5, and the bidirectional shock-absorbing short section 6 constitute a directional drilling tool assembly. The gas distribution and diversion short section 4 is fixedly connected to the rotor of the anti-vibration air screw 5, driving the rotor of the anti-vibration air screw 5 to rotate.

[0053] The anti-vibration air screw 5 includes a rotor, a screw, and an outer tube. There is a certain skew tool angle between the rotor and the screw outer tube. By changing the tool face angle, the drilling trajectory can be controlled.

[0054] The anti-vibration air screw 5 and the bidirectional damping short section 6 form a dual damping system to further reduce the vibration caused by the impact drill string during operation, thereby improving the service life of the drill string.

[0055] The locking section 7, the wireless drilling directional instrument 8, and the non-magnetic drill bit 9 constitute a directional drilling tool assembly. The locking section 7 is fixedly installed at the front end of the wireless drilling directional instrument 8. The bidirectional shock-absorbing section 6 is provided with a positioning slot 604a. The locking section 7 and the positioning slot 604a cooperate to form an axial positioning and locking device for the wireless drilling directional instrument 8, which prevents axial movement during drilling and affects the directional accuracy.

[0056] The positioning and locking device can realize emergency clamping. In the event of accidents such as stuck drill bit, the clamp can be clamped in an emergency, and the wireless drilling surveying instrument 8 can be retrieved by the retrieval tool.

[0057] The impact damping section 3 includes: a first inner tube shaft 301, a front end cover 302, a first sealing ring assembly 303, an outer tube 304, a sliding sleeve 305, a second sealing ring assembly 306, a retaining ring 307, a return spring 308, a rear end cover 309, and a second inner tube shaft 310. Wherein:

[0058] The first inner tube shaft 301 and the second inner tube shaft 310 are fixedly connected by threads. Two retaining rings 307 fix the sliding sleeve 305 to the second inner tube shaft 310. The front end cover 302 and the rear end cover 309 are fixed to the outer tube 304 by threads. The first inner tube shaft 301 and the second inner tube shaft 310 can slide axially. Two sets of return springs 308 are provided between the retaining rings 307 and the front end cover 302 and the rear end cover 309, thereby restricting the position of the first inner tube shaft 301 and the second inner tube shaft 310 in the free state.

[0059] The first inner tube shaft 301 is provided with a first damping vent 301a, and the second inner tube shaft 310 is provided with a second damping vent 309a. A first sealing ring assembly 303 is installed between the front end cover 302 and the rear end cover 309 and between the first inner tube shaft 301 and the second inner tube shaft 309 310, and a second sealing ring assembly 306 is provided between the sliding sleeve 305 and the outer tube 304. The first sealing ring assembly 303 can achieve gas sealing between the first inner tube shaft 301 and the front end cover 302, and between the second inner tube shaft 310 and the rear end cover 309, and the second sealing ring assembly 306 can achieve gas sealing between the cavities of the two return springs 308.

[0060] The impact damping method of the air impact directional drilling drill string assembly given in this embodiment is as follows: When high-pressure air enters the cavity of the two return springs 308 between the first inner tube shaft 301 and the second inner tube shaft 310 and the outer tube 304 through the first damping air hole 301a and the second damping air hole 309a, during impact drilling, the pneumatic impactor 2 drives the first inner tube shaft 301 and the second inner tube shaft 310 to vibrate axially. During the vibration, air flows through the first damping air hole 301a and the second damping air hole 309a between the inner shaft hole and the cavity of the return spring 308, forming a damping force, thereby achieving the purpose of air damping. When the pneumatic impactor 2 drives the first inner tube shaft 301 and the second inner tube shaft 310 to vibrate with a large amplitude, the first damping air hole 301a is blocked by the front end cover 302 or the second damping air hole 309a is blocked by the rear end cover 309. At this time, the air compression generates a large load resistance, thereby further reducing the impact force on the drill string. Compressed air can limit the excessive compression of the return springs 308 by the cavities of the two return springs 308, and at the same time, non-contact shock absorption is achieved through compressed air. It has a simple structure, light weight, and long service life.

[0061] The aforementioned air distribution and diversion section 4 is used to achieve compressed air diversion, controlling the airflow to the air down-the-hole hammer within a set range and not changing with load variations. Excess air is discharged into the annular space, which protects the pneumatic impactor 2, improves rock breaking efficiency, reduces wear on the impact drill bit 1, and extends service life.

[0062] The bidirectional shock-absorbing short section 6 includes: a connector 601, a first elastic body 602, a rod 603, a core tube 604, a second elastic body 605, and a cap 606. The connector 601 is threadedly connected to the rod 603, and the cap 606 is threadedly connected to the rod 603. The core tube 604 is installed inside the rod 603 and can slide axially within the rod 603. The first elastic body 602 and the second elastic body 605 are disposed between the connector 601 and the core tube 604, and between the cap 606 and the core tube 604. The core tube 604 has two positioning grooves 604a on its inner side.

[0063] The locking section 7 includes: a seat shaft 701, retaining balls 702, a first support spring 703, a retaining sleeve 704, and a second support spring 705. The retaining sleeve 704 is fitted onto the seat shaft 701 and can slide back and forth. Four retaining balls 702 are installed in the retaining groove at the front end of the seat shaft 701. The first support spring 703 is located at the bottom of each retaining ball 702. The second support spring 705 is located between the retaining sleeve 704 and the inner shaft step. The retaining sleeve 704 slides back and forth on the seat shaft 701, which can limit and release the retaining balls 702. When the retaining balls 702 are released, the first support spring 703 pushes the retaining balls 702 out of the retaining groove.

[0064] The locking method of the directional measuring instrument 8 in the air impact directional drilling tool assembly given in this embodiment is as follows: When the wireless measuring-while-drilling instrument 8 is lowered to the core tube 604 position of the bidirectional shock-absorbing sub 6, under the guidance of the conical opening on the bidirectional shock-absorbing sub 6 and the conical head on the locking sub 7, the locking sub 7 is inserted into the core tube 604. The core tube 604 pushes the retaining sleeve 704 of the locking sub 7 to compress the two support springs (703, 705) and move backward. When it moves to the slot position of the core tube 604, the first support spring 703 pushes the retaining ball 702 to lock the wireless measuring-while-drilling instrument 8 and the core tube 604, which can prevent the wireless measuring-while-drilling instrument 8 from axially moving during the impact directional drilling process, thus affecting the directional accuracy. When a stuck drill or other bottom hole accident occurs and the wireless measuring-while-drilling instrument 8 needs to be retrieved, simply lower the retrieval tool. When the retrieval axial force exceeds the safety value, the retaining ball 702 can be pressed in to release the stuck instrument.

[0065] The non-magnetic drill bit 9 has an elastic support 902 inside the tube wall 901. When the wireless drilling directional measuring instrument 8 is lowered to the required position and locked, the elastic support 902 stably supports the wireless drilling directional measuring instrument 8, thereby straightening the wireless drilling directional measuring instrument 8 and further reducing vibration to protect the wireless drilling directional measuring instrument 8 and improve measurement accuracy.

[0066] The air impact directional drilling tool assembly presented in this embodiment can be used for impact directional drilling applications in complex, easily leaky formations and hard formations with poor drillability. By changing the rock-breaking method of the drive directional drill bit, it reduces the rock-breaking effort, decreases drill bit wear, and improves drilling efficiency in hard rock. Simultaneously, impact rock breaking requires less axial pressure compared to cutting rock breaking, effectively preventing borehole deviation and improving the smoothness of the directional drilling trajectory and construction efficiency. During impact rock breaking, the rock cutting resistance is low, and the low-torque operation of the vibration-resistant air screw effectively extends screw life.

[0067] By installing vibration damping devices between the pneumatic impactor and the anti-vibration air screw, between the anti-vibration air screw and the wireless drilling rig, and in the non-magnetic drilling tool, and using the anti-vibration air screw to form a multi-level all-round vibration damping system, the accuracy of directional drilling trajectory measurement and control is improved, while also improving the reliability and service life of the drilling tool.

[0068] The following are examples provided by the inventor.

[0069] Example:

[0070] See Figure 1This embodiment provides a drill string assembly for air impact directional drilling, comprising, from left to right, an impact bit 1, a pneumatic impactor 2, an impact damping sub 3, an air distribution sub 4, an anti-vibration air screw 5, a bidirectional damping sub 6, a locking sub 7, a wireless measurement-while-drilling instrument 8, a non-magnetic drill string 9, and a conventional drill string 10; wherein:

[0071] The impact drill bit 1 is installed on the pneumatic impactor 2. When a certain amount of high-pressure air is introduced into the pneumatic impactor 2, the pneumatic impactor 2 drives the impact drill bit 1 to reciprocate and impact rock. The pneumatic impactor 2 is connected to the impact damping section 3. The impact damping section 3 can reduce the vibration effect caused by the impact of the drill bit on the left. The impact damping section 3 is connected to the air distribution and diversion section 4 by a thread. The air distribution and diversion section 4 controls the air flow into the pneumatic impactor 2 on the left. Excess air is discharged into the annulus. The air distribution and diversion section 4 can realize the quantitative control of the air supply to the pneumatic impactor 2.

[0072] The rotor of the anti-vibration air screw 5 is connected to the air distribution and diversion section 4 by a thread. Compressed air enters the anti-vibration air screw 5 and drives the rotor to rotate, thereby driving the drill string at the left end of the anti-vibration air screw 5 to rotate as a whole, and finally driving the impact drill bit 1 to rotate, assisting in rock breaking.

[0073] The right end of the anti-vibration air screw 5 is fixedly connected to the bidirectional shock-absorbing short section 6, which further reduces the impact of rock fragmentation at the drill bit tip. The bidirectional shock-absorbing short section 6 and the locking short section 7 form a positioning and locking mechanism, which can realize the positioning and locking of the wireless drilling directional instrument 8 fixedly connected to the locking short section 7. The right side of the bidirectional shock-absorbing short section 6 is fixedly connected to the non-magnetic drill bit 9 through a threaded connection. After the wireless drilling directional instrument 8 is positioned and locked, the non-magnetic drill bit 9 can straighten the wireless drilling directional instrument 8 and further reduce vibration. The right end of the non-magnetic drill bit 9 can be fixedly connected to a conventional drill bit. In the entire drill bit assembly, a high-pressure air circulation channel is provided to provide power for the pneumatic impactor 2 and the anti-vibration air screw 5, and to provide a medium for bottom hole cuttings cleaning, drill bit cooling, and slag return.

[0074] See the structural diagram of the impact damping short section. Figure 2 It includes a first inner tube shaft 301, a front end cover 302, a first sealing ring group 303, an outer tube 304, a sliding sleeve 305, a second sealing ring group 306, a retaining ring 307, a return spring 308, a rear end cover 309, and a second inner tube shaft 310.

[0075] The first inner tube shaft 301 and the second inner tube shaft 310 are connected by threads. Two retaining rings 307 fix the sliding sleeve 305 to the second inner tube shaft 310, forming a sliding assembly 3a. The front end cover 302 and the rear end cover 309 are fixed to the outer tube 304 by threads. The first inner tube shaft 301 and the second inner tube shaft 310 can slide axially within the outer tube 304. Two sets of return springs 308 are provided between the retaining rings 307 and the front end cover 302 and the rear end cover 309, thereby restricting the position of the sliding assembly in the inner tube 301 in the free state. A first damping vent 301a is provided on the first inner tube shaft 301, and a second damping vent 309a is provided on the second inner tube shaft 310. A first sealing ring group 303 is installed between the front end cover 302 and the rear end cover 309 and the first inner tube shaft 301 and the second inner tube shaft 310, and a second sealing ring group 306 is provided between the sliding sleeve 305 and the outer tube 304. The first sealing ring group 303 can achieve gas sealing between the first inner tube shaft 301 and the front end cover 302, and between the second inner tube shaft 310 and the rear end cover 309. The second sealing ring group 306 can achieve gas sealing between the cavities of the two return springs 308.

[0076] Impact damping short section damping process as follows Figure 3 As shown, where Figure 3 Figure a shows the position of the sliding component 3a in its free state. At this time, high-pressure air enters the cavities of the two return springs 308 through the first damping vent 301a and the second damping vent 309a. Figure 3 As shown in Figure b, when the pneumatic impactor 2 drives the sliding assembly 3a to move to the right, it compresses the right-side return spring cavity. The compressed air in the right-side return spring cavity needs to flow out through the second damping air hole 309a. Due to the high speed of the impact motion and the small size of the damping hole, an air damping force is generated, thereby reducing the amplitude. When the amplitude is large, the sliding assembly 3a moves to the right to... Figure 3 In state C, the cavity of the right-hand spring 308 becomes a closed cavity. Further compression of the air will generate greater pressure, further reducing the amplitude. Due to the presence of the sealed cavity, fatigue damage caused by excessive compression of the return spring 308 and frequent hard impacts from conventional mechanical damping can be avoided. When the pneumatic impactor 2 drives the sliding assembly to move to the left, its working process is the same as the rightward movement process.

[0077] See the structural schematic diagram of the bidirectional damping short section 6. Figure 4 It includes a connector 601, a first elastic body 602, a rod body 603, a core tube 604, a second elastic body 605, and a cap 606, wherein:

[0078] The connector 601 is fixedly connected to the rod body 603 by threads, and the plug 606 is fixedly connected to the rod body 603 by threads. A core tube 604 is installed inside the rod body 603. The core tube 604 can slide axially inside the rod body 603. A first elastic body 602 and a second elastic body 605 are provided between the connector 601 and the core tube 604 and between the plug 606 and the core tube 604. There are two positioning grooves 604a on the inner side of the core tube.

[0079] In this embodiment, see the structural diagram of locking section 7. Figure 5 The device includes: a seat shaft 701, retaining balls 702, a first support spring 703, a retaining sleeve 704, and a second support spring 705. The retaining sleeve 704 is fitted onto the seat shaft 701 and can slide back and forth. Four retaining balls 702 are installed in the retaining slot at the front end of the seat shaft. The first support spring 703 is located at the bottom of the retaining balls. The second support spring 705 is located at the stepped portion of the retaining sleeve 704 and the seat shaft 701. Sliding the retaining sleeve 704 left and right allows for the limiting and releasing of the retaining balls 702. When the retaining balls 702 are released, the first support spring 703 pushes the retaining balls (704) out of the retaining slot. The retaining sleeve 704 and the seat shaft 701 are provided with a first air channel 704a and a second air channel 701a.

[0080] For locking and securing of the short section, please refer to [link / reference]. Figure 6 As shown. Figure 6 When the wireless drilling directional instrument 8 is lowered to the core tube 604 position of the bidirectional damping sub 6, guided by the conical opening on the bidirectional damping sub 6 and the cone at the front end of the seat shaft 701 on the locking sub 7, the seat shaft 701 is inserted into the core tube 604. The core tube 604 pushes the ferrule 704 to compress the second support spring 705 and move backward. When it moves to the positioning slot 604a position of the core tube 604, the first support spring 703 pushes the locking ball 702 to lock the sub 7 and the core tube 604, which can prevent the wireless drilling directional instrument 8 from axially moving during impact directional drilling, thus affecting the directional accuracy. When a stuck drill or other bottom hole accident occurs and the wireless drilling directional instrument 8 needs to be retrieved, simply lower the retrieval tool. When the axial force of the retrieval tool exceeds the safety value, the locking ball 702 can be pressed in to release the stuck instrument.

[0081] See the structural diagram of the non-magnetic drill bit. Figure 7 An elastic support 902 is provided on the inner wall 901 of the non-magnetic drill bit 9. When the wireless drilling comprehension instrument 8 is lowered to the positioning position and locked, the elastic support 902 stably supports the wireless drilling comprehension instrument 8, thereby straightening the wireless drilling comprehension instrument 8 and further reducing vibration, thus protecting the instrument and improving measurement accuracy.

[0082] The above description, in conjunction with the accompanying drawings, provides a detailed description of the drill string assembly for air impact directional drilling in this embodiment. The above embodiments are merely illustrative, and the present invention is not limited to the above embodiments. Those skilled in the art will recognize that, without departing from the technical solutions protected by the claims of the present invention, additions or simple modifications to the technical solutions can be made, and all such modifications should fall within the scope of protection defined by the claims of this application.

Claims

1. A drill assembly for air-impingement directional drilling, comprising: The air impact directional drilling tool assembly includes an impact drill bit (1), a pneumatic impactor (2), an impact damping sub (3), an air distribution sub (4), an anti-vibration air screw (5), a bidirectional damping sub (6), a locking sub (7), a wireless measurement-while-drilling instrument (8), a non-magnetic drill string (9), and a conventional drill string (10) and a key sub (11); wherein: The impact drill bit (1), pneumatic impactor (2), and impact damping short section (3) constitute an impact rock breaking assembly. The impact drill bit (1) is installed at the front end of the pneumatic impactor (2), and the rear end of the pneumatic impactor (2) is fixedly connected to the impact damping short section (3). This assembly is used to improve rock breaking efficiency and drilling efficiency during drilling in complex formations. The pneumatic impactor (2) is provided with high-frequency impact force by compressed air, which causes the impact rod of the pneumatic impactor (2) to repeatedly impact the impact drill bit (1), thereby achieving high-frequency impact rock breaking by the impact drill bit (1). During the rock breaking process, the impact damping section (3) is used to buffer the impact of the pneumatic impactor (2) on the drill string, thereby improving the service life and reliability of the drill string. The gas distribution splitting short section (4), the anti-vibration air screw (5), and the bidirectional damping short section (6) constitute a directional drilling tool assembly. The gas distribution splitting short section (4) is fixedly connected to the rotor of the anti-vibration air screw (5), and the rotor of the anti-vibration air screw (5) is driven to rotate by compressed air. The anti-vibration air screw (5) includes a rotor, a screw and an outer tube. There is a certain angle between the rotor and the outer tube for the tool face. By changing the tool face angle, the drilling trajectory control of the drill string can be achieved. The anti-vibration air screw (5) and the bidirectional damping short section (6) form a dual damping system to further reduce the vibration caused by the drilling string during operation and improve the service life of the drilling string. The locking section (7), the keyway section (11), the wireless drilling directional instrument (8), and the non-magnetic drill string (9) constitute a directional drilling tool assembly. The locking section (7) is fixedly installed at the front end of the wireless drilling directional instrument (8). The bidirectional shock-absorbing section (6) is provided with a positioning slot (604a). The locking section (7) and the positioning slot (604a) cooperate to form an axial positioning and locking device for the wireless drilling directional instrument (8) to prevent axial movement during the drilling process and affect the directional accuracy. The axial positioning and locking device can realize emergency unjamming. When a stuck drill accident occurs, it can be unjammed in an emergency and the wireless drilling directional instrument (8) can be retrieved by a retrieval tool. The main function of the keyway sub (11) is to provide a stable setting environment for the drill string assembly of air impact directional drilling.

2. The air-hammer directional drilling assembly of claim 1, wherein, The shock-absorbing short section (3) includes: a first inner tube shaft (301), a front end cover (302), a first sealing ring group (303), an outer tube (304), a sliding sleeve (305), a second sealing ring group (306), a retaining ring (307), a return spring (308), a rear end cover (309), and a second inner tube shaft (310), wherein: The first inner tube shaft (301) and the second inner tube shaft (310) are connected by threads. Two retaining rings (307) fix the sliding sleeve (305) on the second inner tube shaft (310). The front end cover (302) and the rear end cover (309) are fixed to the outer tube (304) by threads. The first inner tube shaft (301) and the second inner tube shaft (310) can slide axially. Two sets of return springs (308) are provided between the retaining ring (307) and the front end cover (302) and the rear end cover (309) to restrict the positions of the first inner tube shaft (301) and the second inner tube shaft (310) in the free state; The first inner tube shaft (301) is provided with a first damping air hole (301a), and the second inner tube shaft (310) is provided with a second damping air hole (309a); a first sealing ring group (303) is installed between the front end cover (302) and the rear end cover (309) and the first inner tube shaft (301) and the second inner tube shaft (310), and a second sealing ring group (306) is provided between the sliding sleeve (305) and the outer tube (304); wherein, the first sealing ring group (303) is used to realize the gas seal between the first inner tube shaft (301) and the front end cover (302), and the second inner tube shaft (310) and the rear end cover (309), and the second sealing ring group (306) is used to realize the gas seal between the cavities of the two return springs (308); When compressed air enters the cavity of the return spring (308) between the first inner tube shaft (301) and the second inner tube shaft (310) and the outer tube (304) through the first damping air hole (301a) and the second damping air hole (309a), during impact drilling, the pneumatic impactor (2) drives the first inner tube shaft (301) and the second inner tube shaft (310) to vibrate axially. During the vibration process, air passes through the first damping air hole (301a) and the second damping air hole (309a) between the first inner tube shaft (301) and the second inner tube shaft (310) and the outer tube (304) and the cavity of the return spring (308). The flow of air vents (309a) generates damping force, thereby achieving the purpose of air shock absorption. When the pneumatic impactor (2) drives the first inner tube shaft (301) and the second inner tube shaft (310) to vibrate at a large amplitude, the first damping air vent (301a) is blocked by the front end cover (302) or the second damping air vent (309a) is blocked by the rear end cover (309). At this time, the air compression generates a large load resistance, thereby further reducing the impact of the impact force on the drill string. The compressed air can limit the excessive compression of the cavity of the two return springs (308) on the return springs (308), and at the same time, non-contact shock absorption is achieved through compressed air.

3. The drill string assembly for air impact directional drilling as described in claim 1, characterized in that, The air distribution and diversion section (4) is used to divert compressed air, control the airflow to the air downhole hammer within a set range, and ensure that it does not change with the load. Excess air is discharged into the annulus to prevent the impactor from being damaged due to excessive impact frequency. At the same time, the diverted compressed air can be used for the return of rock cuttings from the well. While protecting the pneumatic impactor (2), it improves the rock breaking efficiency, reduces the wear of the impact drill bit (1), and increases the service life.

4. The drill string assembly for air impact directional drilling as described in claim 1, characterized in that, The bidirectional damping short section (6) includes: a joint (601), a first elastic body (602), a rod (603), a core tube (604), a second elastic body (605), and a cap (606), wherein: The connector (601) is fixedly connected to the rod body (603) by threads, and the plug (606) is fixedly connected to the rod body (603) by threads. A core tube (604) is installed inside the rod body (603). The core tube (604) can slide axially inside the rod body (603). A first elastic body (602) and a second elastic body (605) are provided between the connector (601) and the core tube (604) and between the plug (606) and the core tube (604). There are two positioning slots (604a) on the inner side of the core tube (604).

5. The drill string assembly for air impact directional drilling as described in claim 1, characterized in that, The locking section (7) includes: a seat shaft (701), a retaining ball (702), a first support spring (703), a retaining sleeve (704), and a second support spring (705). The retaining sleeve (704) is fitted onto the seat shaft (701) and slides back and forth on the seat shaft (701). Four retaining balls (702) are installed in the retaining slot at the front end of the seat shaft (701). The first support spring (703) is provided at the bottom of the retaining ball (702). The second support spring (705) is provided at the step part of the retaining sleeve (704) and the seat shaft (701). The retaining sleeve (704) slides back and forth on the seat shaft (701) to realize the limiting and release of the retaining ball (702). When the retaining ball (702) is released, the first support spring (703) pushes the retaining ball (702) to move out of the retaining slot.

6. The drill string assembly for air impact directional drilling as described in claim 1, characterized in that, The non-magnetic drill bit (9) has an elastic support (902) inside the tube wall (901). When the wireless drilling skewing instrument (8) is lowered to the required position and locked, the elastic support (902) stably supports the wireless drilling skewing instrument (8), thereby straightening the wireless drilling skewing instrument (8) and further reducing vibration to protect the wireless drilling skewing instrument (8) and improve measurement accuracy.

7. The air impact directional drilling tool assembly according to any one of claims 1 to 6 is used for impact directional drilling in complex, easily leaky formations and hard formations with poor drillability.

8. The application as described in claim 7, characterized in that, By changing the traditional directional drilling method of rock breaking, the rock breaking work is reduced, the wear of the drill bit is reduced, and the drilling efficiency of hard rock is improved. At the same time, impact rock breaking requires less axial pressure than cutting rock breaking, which can effectively prevent the borehole deviation, improve the smoothness of the directional drilling trajectory and the construction efficiency of directional drilling. During the impact rock breaking process, the rock cutting resistance is small, and the low torque operation of the anti-vibration air screw can effectively improve the screw life. By installing vibration damping devices between the pneumatic impactor and the anti-vibration air screw, between the anti-vibration air screw and the wireless drilling rig, and in the non-magnetic drill string, and using the anti-vibration air screw to form a multi-level all-round vibration damping system, the accuracy of directional drilling trajectory measurement and control is improved, while also improving the reliability and service life of the drill string.

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