CN216922030U - Continuous casing drilling tool system with double impregnated diamond drill bits - Google Patents

Abstract

A double-impregnated diamond drill bit continuously follows the casing drilling tool system, including an inner drill bit, an outer drill bit, a drill pipe, a casing joint and a casing, etc. The inner drill bit is driven by the drill pipe to rotate and provide drilling pressure, and the outer drill bit is driven by the inner drill bit. The rotation is driven by the transmission key, and the drilling pressure can be provided by the casing or by the drill pipe under the combined action of the inner and outer drill bits. The design of multiple pressure bearings and guide bearings can realize the outer drill bit and its upper casing. The function of independent rotation, the characteristic spiral groove on the surface of the casing itself is conducive to the rotation and release of the casing under the action of friction in the broken formation, and the high carcass design of the inner and outer bits increases the drilling depth, thereby improving At the same time, due to the continuous drilling during the drilling process and the continuous follow-up of the casing, the friction between the casing and the hole wall always appears as dynamic friction, which is higher than the static friction generated when the drilling is stopped. Said, can significantly reduce the energy loss.

Description

A double impregnated diamond drill bit continuous casing drilling tool system

technical field

The invention belongs to the technical field of deep drilling construction, and in particular relates to a double-impregnated diamond drill bit continuously followed by a casing drilling tool system.

Background technique

In order to improve the stability of the hole wall and the construction efficiency of drilling into broken formations such as pebble and gravel, the casing drilling technology is usually used to maintain the stability of the hole wall, and the effect is obvious. At present, the conventional follow-pipe drilling technology is mainly the down-the-hole hammer follow-pipe drilling in a gas environment. There are two methods: one is eccentric follow-pipe drilling, and the other is concentric follow-pipe drilling. The eccentric follow-pipe drilling drives the eccentric drill to drill through the vibration and impact of the impactor in the drill assembly. When the eccentric drill is subjected to centrifugal force and frictional force, the eccentric drill bit deflects outwards, thereby achieving expansion The purpose of the hole diameter, and then through the impact of the rod stabilizer in the drilling tool assembly, the casing is driven to follow up, and the cuttings generated in the borehole are blown out of the hole by the air compressor through the keyway on the rod stabilizer. After the drilling is completed, the eccentric is retracted back into the casing by reversing, and then it is lifted out of the casing, and the casing is left in the hole to protect the wall to form a hole; The concentric sleeves impact and break the rock together to make holes, and at the same time use the reaming action of the concentric sleeves to bring the casing into the hole. The concentric sleeves are provided with key grooves. After reaching the bedrock, the center bit is reversed and exits through the concentric sleeves. The concentric follow-up pipe can better solve the problems of sticking and boulder drilling caused by complex geological conditions during eccentric follow-up pipe drilling, which is more conducive to construction operations and improves drilling efficiency.

However, the above two conventional methods are only suitable for drilling shallower than 100 meters. With the increase of the well depth, due to the irregularity of the well wall in the percussion rotary drilling under the gas environment, the frictional resistance between the casing and the well wall increases. In addition to the fragmentation of the ground, it is very easy to get stuck. Especially for hot-dry rock drilling, because the burial depth of hot-dry rock is more than 1000 meters, and the wall of dry-hot rock is greatly affected by thermal stress and quenching, it is easy to rupture and cause drilling. Therefore, the existing percussive and tubular drilling technologies and techniques have been unable to meet the drilling requirements of deep wells in broken formations.

In order to solve the above problems, it is necessary to carry out a research on a casing drilling system with a wall protection function in a mud environment. The use of double-impregnated diamond bits can theoretically realize continuous casing drilling in deep well broken formations and dry hot rock formations. Purpose. Therefore, it is of great significance to innovate the research on the continuous and casing drilling tool system of the impregnated diamond bit in the mud environment.

SUMMARY OF THE INVENTION

The invention proposes a double-impregnated diamond drill bit continuous casing drilling tool system, aiming at realizing deep well breakage and continuous casing drilling in dry and hot rock formations.

A double impregnated diamond drill bit is continuously followed by a casing drilling tool system, comprising an inner drill bit, an outer drill bit, a first transmission key, a second transmission key, an inner drill bit limit, an outer drill bit limit, a first copper sleeve, and a second copper sleeve. Sleeve, outer bit joint, inner bit joint, shrapnel, inner seal, outer seal, lower pressure bearing, middle pressure bearing, upper pressure bearing, lower guide positive bearing limit, upper guide positive bearing limit, guide Positive bearing, outer drill joint limit, drill pipe, casing joint and casing;

Different from the conventional impregnated diamond bit, the inner bit has a specific structure. The upper end of the inner bit is fixedly connected to the lower end of the inner bit joint, the upper end of the inner bit joint is fixedly connected to the lower end of the drill pipe, and the outer side of the inner bit is uniformly distributed with N first keyways. N≥1, there are N second keyways evenly distributed on the inner side of the inner bit limit, N≥1, N first transmission keys are fixed between the first keyway and the second keyway, N≥1;

The outer drill bit is also different from the conventional impregnated diamond drill bit. It has a specific structure. The inner circumferential direction is uniformly distributed with N third keyways, N≥1, and the outer circumferential limit of the outer drill bit is uniformly distributed with N fourth keyways. N ≥1,N second transmission keys are fixed between the third keyway and the fourth keyway;

The outer side of the inner bit limit is uniformly distributed with N first bumps, N≥1, and the inner side of the outer bit limit is uniformly distributed with N second bumps, N≥1, and the inner side of the outer bit limit The bottom is provided with a first boss, the limit of the inner drill bit is concentrically connected with the limit of the outer drill bit, and the first bump is limited to the upper end of the first boss. Interfering and engaging with the second bump to realize the limited rotation of the inner drill bit and then drive the outer drill bit to rotate in the limited circumferential direction;

The lower end of the outer bit joint is fixedly connected with the upper end of the outer bit, and the upper part of the outer bit joint is uniformly distributed with several mud holes penetrating into the inside of the outer bit joint, and the outer bit joint is also provided with a first threaded interface, a first groove and a second The groove, the outer wall of the first copper sleeve and the first threaded interface are fixedly connected by threads, the elastic sheet is arranged in the second groove, the inner seal is arranged in the first groove, and the limit lower end of the outer drill bit joint is fixed with the upper end of the outer bit joint connection, the inner drill bit joint is fixedly connected with the second copper sleeve, the second copper sleeve is limited to the upper end of the first copper sleeve, and the first copper sleeve and the second copper sleeve can rotate concentrically, and then the outer drill bit joint and the inner drill bit joint are connected. The annular gap is sealed, and the inner diameter of the first copper sleeve is smaller than the outer diameter of the second copper sleeve;

The lower end of the casing is fixedly connected with the upper end of the casing joint, the casing joint is provided with a third groove and a fourth groove, the lower guide bearing limit and the upper guide bearing limit are fixedly connected with the casing joint, and the guide bearing The upper and lower ends of the inner ring are respectively pressed against the upper end face of the lower guide bearing limit and the lower end face of the upper guide bearing limit. The lower end surface of the limit is closely connected, the lower surface of the lower pressure bearing is in close contact with the upper end surface of the shrapnel, the upper end of the inner seal is in close contact with the lower end surface of the casing joint, and the lower surface of the middle pressure bearing is in close contact with the upper limit surface of the upper guide positive bearing. Contact, the upper surface of the middle pressure bearing is in close contact with the lower surface of the inner side of the outer drill joint limit, the upper pressure bearing is installed in the third groove, and the lower surface of the upper pressure bearing is in close contact with the outer upper surface of the outer drill joint limit , the outer seal is installed in the fourth groove, and the outer seal is in close contact with the upper surface of the outer limit of the outer drill bit joint.

Furthermore, the outer surface of the casing and casing joint is machined with a characteristic helical groove structure. When the casing is stuck by the broken rock, the casing is driven to rotate by the ground equipment, so that the casing is driven by the ground equipment during the rotation. The characteristic spiral groove structure on its own surface realizes the rotation release.

More specifically, when the first bump on the outer side of the inner bit limit contacts with the second bump on the inner side of the outer bit limit, the inner bit nozzle of the inner bit and the nozzle of the outer bit are in a positive relationship.

Furthermore, the path of mud circulation during drilling is as follows: outflow from the inner bit, through the inner bit nozzle and the outer bit nozzle at the bottom of the outer bit, into the annular space formed by the outer bit and the hole wall, and finally through the outer bit joint. The mud hole on the upper part enters the annular space formed by the drill pipe and the casing to complete the overall circulation.

Furthermore, the path of mud circulation during drilling is as follows: a part of the mud flows out from the inner bit, flows through the inner bit nozzle and the outer bit nozzle at the bottom of the outer bit, enters the annular space formed by the outer bit and the hole wall, and finally passes through the outer bit. The mud hole on the drill bit joint enters into the annular gap formed by the drill pipe and the casing;

The remaining part flows out from the inner bit, passes through the inner bit nozzle, enters the annulus formed by the inner bit and the outer bit, flows out through the outer bit nozzle on the upper part of the outer bit, enters the annular space formed by the outer bit and the hole wall, and finally passes through the outer bit The mud hole on the joint enters the annular gap formed by the drill pipe and the casing to complete the overall circulation.

Beneficial effects of the present invention:

1. The small cuttings produced by the rotary drilling of the broken rock with the diamond-impregnated double drill bits can effectively solve the problem that the annular gap between the inner and outer pipe assemblies of the concentric follower pipe is stuck by large pieces of cuttings and cannot be rotated normally;

2. Combined with high-frequency and low-amplitude impact crushed rock, the disturbance to the well wall is small, the deep interference to the broken well wall is reduced, the hole wall is more regular, the drill bit and the casing rotate independently, and the probability of jamming is small, even if a jam occurs Because the well wall is relatively regular, the well wall has a weak ability to wrap the casing, and the degree of blocking is relatively low, which increases the ability of the drilling tool system to unblock;

3. The inner bit is driven to rotate by the drill pipe, and the outer bit is driven to rotate by the inner bit through the transmission key. The inner and outer drill bits are all impregnated diamond bits, which have less disturbance to the well wall compared to the DTH hammer during the drilling process, the hole wall is complete, the probability of jamming is small, and the degree of blocking is low. Increase the drilling depth, and then increase the depth of the follow-up pipe, realize continuous follow-up pipe drilling, and keep drilling in the middle until the life of the bit is reached or the designed pipe-following depth is reached;

4. In the process of continuous follow-up drilling, the casing and the hole wall always exhibit dynamic friction, and the energy loss is relatively small. The inner drill bit provides the WOB through the drill pipe, and the outer drill bit can obtain the WOB through the casing, and can obtain the WOB through the mutual cooperation between the inner drill bit limit and the outer drill bit limit;

5. The design of pressure bearing and guide bearing in this mechanism can realize the function of independent rotation of the outer drill bit and the casing above it. The drill bit structure adopted by the inner drill bit can effectively avoid the problem of local false circulation of mud in the high-matrix drill bit. , limit the mud circulation path, so that the mud can reach the bottom of the hole smoothly, and then cooperate with the outer drill bit to realize the mud circulation, complete the cooling of the drill bit and the cleaning of the cuttings at the bottom of the hole;

6. Based on the above design, the drilling tool system can realize continuous casing drilling in deep fractured formations, effectively solve the problems of stuck drilling, buried drilling, and hole collapse caused by formation fractures in deep wells, significantly reducing energy loss and shortening drilling time. time and improve drilling efficiency.

Description of drawings

FIG. 1 is an overall cross-sectional view of the present invention.

FIG. 2 is a three-dimensional schematic diagram of the inner drill bit of the present invention.

FIG. 3 is a three-dimensional schematic diagram of the outer drill bit of the present invention.

FIG. 4 is a three-dimensional schematic diagram of the limit of the inner drill bit according to the present invention.

FIG. 5 is a three-dimensional schematic diagram of the limiting position of the outer drill bit according to the present invention.

FIG. 6 is a perspective cross-sectional view of the outer drill bit joint of the present invention.

7 is a perspective cross-sectional view of the casing joint of the present invention.

FIG. 8 is an overall schematic diagram of the casing and the casing joint of the present invention.

FIG. 9 is a schematic diagram of the principle of pressure transmission and torsion isolation according to the present invention.

FIG. 10 is a schematic diagram of the mud circulation trajectory in the present invention.

Fig. 11 is a schematic diagram of the alignment principle of the inner and outer bit nozzles of the present invention.

Detailed ways

Please refer to Fig. 1 to Fig. 11 , a double-impregnated diamond drill bit continuous casing drilling tool system includes an inner drill bit 1, an outer drill bit 2, a first transmission key 3, a second transmission key 4, an inner drill bit limit 5, Outer drill bit limit 6, first copper sleeve 7, second copper sleeve 8, outer drill bit joint 9, inner drill bit joint 10, shrapnel 11, inner seal 12, outer seal 13, lower bearing 14, middle bearing Bearing 15, upper pressure bearing 16, lower guide bearing limit 17, upper guide bearing limit 18, guide bearing 19, outer drill bit joint limit 20, drill pipe 21, casing joint 22 and casing 23; The N here is specified by 4;

The upper end of the inner drill bit 1 and the lower end of the inner drill bit joint 10 are fixedly connected by threads, the upper end of the inner drill bit joint 10 and the lower end of the drill pipe 21 are fixedly connected by threads, and the outer side of the inner drill bit 1 is uniformly distributed with four first key grooves 101. There are 4 second key grooves 501 evenly distributed on the inner side of position 5, and the first transmission key 3 is fixed between the first key groove 101 and the second key groove 501;

Four third keyways 201 are evenly distributed on the inner side of the outer drill bit 2 , four fourth keyways 601 are evenly distributed on the outer side of the outer drill bit limiter 6 , and the second transmission key 4 is fixed on the third keyway 201 and the fourth keyway 201 . Between the keyway 601;

Four first bumps 502 are evenly distributed on the outer side of the inner bit limiter 5 , four second bumps 602 are evenly distributed on the inner side of the outer bit limiter 6 , and the inner bottom of the outer bit limiter 6 is provided with The first boss 603, the inner bit limit 5 and the outer bit limit 6 are concentrically connected to rotate, and the first bump 502 is limited to the upper end of the first boss 603. When the inner bit limit 5 rotates, it passes through the first boss 603. A bump 502 engages with the second bump 602 in interference, so as to realize the rotation of the inner drill bit limit 5 and then drive the outer drill bit limit 6 to rotate in the circumferential direction;

The lower end of the outer bit joint 9 is fixedly connected with the upper end of the outer bit 2 by means of threads. The upper end of the outer bit joint 9 is uniformly distributed with several mud holes 901 penetrating into the interior of the outer bit joint 9. The outer bit joint 9 is also provided with a first threaded interface. 902, the first groove 903 and the second groove 904, the outer wall of the first copper sleeve 7 and the first threaded interface 902 are fixedly connected by threads, the elastic piece 11 is arranged in the second groove 904, and its function is to: make the lower pressure bearing The bearing 14 can better withstand the pressure, the inner seal 12 is arranged in the first groove 903, the lower end of the outer drill bit limiter 20 and the upper end of the outer drill bit connector 9 are fixedly connected by threads, and the inner drill bit connector 10 and the second copper sleeve 8 pass through Threaded fixed connection, the second copper sleeve 8 is limited to the upper end of the first copper sleeve 7 and the first copper sleeve 7 and the second copper sleeve 8 can be rotated concentrically, similar to the mechanical seal structure, and the main function is to connect the outer drill bit joint 9 It is sealed with the annular gap of the inner drill bit joint 10, and the inner diameter of the first copper sleeve 7 is smaller than the outer diameter of the second copper sleeve 8, so that the vertical downward translation movement of the second copper sleeve 8 in the axial direction is affected by the first copper sleeve. Copper sleeve 7 restrictions;

The lower end of the casing 23 and the upper end of the casing joint 22 are fixedly connected by threads. The casing joint 22 is provided with a third groove 221 and a fourth groove 222. The lower guide positive bearing limit 17 and the upper guide positive bearing limit 18 are connected with The casing joint 22 is fixedly connected by threads. The upper and lower ends of the inner ring of the guide bearing 19 are respectively pressed against the upper end face of the lower guide bearing limit 17 and the lower end face of the upper guide bearing limit 18. The outer ring of the guide bearing 19 is connected to the outer The inner wall of the drill bit joint 9 is fixedly connected, the upper surface of the lower pressure bearing 14 is closely connected with the lower end surface of the lower guide bearing limit 17, the lower surface of the lower pressure bearing 14 is in close contact with the upper end surface of the elastic sheet 11, and the upper end of the inner seal 12 is connected with the casing joint 22 The lower end face is in close contact, the lower surface of the middle pressure bearing 15 is in close contact with the upper surface of the upper guide positive bearing limit 18, the upper surface of the middle pressure bearing 15 is in close contact with the inner lower surface of the outer drill joint limit 20, and the upper bearing The bearing 16 is installed in the third groove 221, and the lower surface of the upper pressure bearing 16 is in close contact with the upper surface of the outer side of the outer drill joint limit 20, the outer seal 13 is installed in the fourth groove 222, and the outer seal 13 It is in close contact with the upper surface of the outer side of the limiter 20 of the outer drill bit.

Furthermore, with reference to FIG. 8 , the outer surfaces of the casing 23 and casing joint 22 are processed with a characteristic helical groove structure 24; Now, the casing 23 can be driven by the ground equipment, so that the casing 23 can be rotated and unblocked by relying on the characteristic helical groove structure on its own surface during rotation.

Furthermore, the inner diameter of the first copper sleeve 7 is smaller than the outer diameter of the second copper sleeve 8, the inner diameter of the first copper sleeve 7 is larger than the outer diameter of the first transmission key 3, and the inner diameter of the first copper sleeve 7 is larger than the first bump 502 outer diameter, so that the vertical downward translation movement of the second copper sleeve 8 in the axial direction is restricted by the first copper sleeve 7 .

Furthermore, referring to Fig. 2, Fig. 3, Fig. 10 and Fig. 11, the working layer structures of the inner bit and the outer bit in this mechanism both use a specific high-matrix bit designed by the research group. The specific structural design of the working layer of the inner drill bit 1 can be found in the patent “Super-high working layer involute nozzle impregnated diamond drill bit and its preparation method”, the patent application number is CN202111097075.2; the specific structural design of the working layer of the outer drill bit 2 can be found in the The patent "Integrated Cutting Teeth Impregnated Diamond Bit", the patent application number is CN201910991035.9. The steel body structure of the inner and outer drill bits is different from that of the conventional impregnated diamond drill bits. In order to match the specific structure of the modified drilling tool system, the high carcass design of the inner and outer drill bits can increase the drilling depth, thereby increasing the depth of the follow-up pipe, which can achieve Drill continuously with the casing until the life of the bit is reached. In actual drilling, the height design of the carcass of the inner bit and the outer bit is determined according to the actual drilling requirements. The structural design of the inner drill bit 1 can effectively avoid the occurrence of local false circulation of mud in the high-matrix drill bit. Based on the above design, no matter how high the carcass height of the inner bit and the outer bit is, the mud will be transported to the bottom of the borehole first to cool the bit and clean the cuttings at the bottom of the hole. The inner bit and the outer bit cooperate with each other to realize continuous drilling with the casing, and the drilling will not stop in the middle until the life of the bit or the drilling design requirements are met, which can greatly shorten the drilling time, save the drilling cost, and reduce the drilling process. energy loss. Improve drilling efficiency.

Furthermore, referring to FIGS. 4 , 5 and 11 , the maximum outer diameter of the inner drill stop 5 is larger than the minimum inner diameter of the outer drill stop 6 . In actual motion, the first boss 502 provided on the outer side of the inner bit limiter 5 will be blocked by the first boss 603 provided on the inner side of the outer drill bit limiter 6, thereby restricting its axial vertical downward translation movement; at the same time , the first bump 501 provided on the outer side of the inner drill bit limit 5 will be blocked by the second bump 602 provided on the inner side of the outer drill bit limit 6, thereby restricting its circumferential rotational movement, so that the inner drill bit limit 5 can only be in a certain As shown in FIG. 11 , when the first bump 502 on the outer side of the inner drill bit limit 5 is in contact with the second bump 602 on the inner side of the outer drill bit limit 6, the inner bit nozzle 102 of the inner drill bit 1 It is in a positive relationship with the outer drill nozzle 202 of the outer drill 2 . At this time, the rotation of the inner drill bit 1 will drive the rotation of the outer drill bit 2 .

Further, referring to FIG. 9 , in the area ② between the outer drill bit joint 9 and the casing joint 22 , there are elastic sheets 11 , an inner seal 12 , an outer seal 13 , a lower pressure bearing 14 , and a middle pressure bearing 15 , The upper pressure bearing 16, the guide bearing 19, the lower guide bearing limit 17 and the upper guide bearing limit 18. Based on the above design, the outer bit joint 9 located in the area ③ will be subjected to the pressure P exerted by the casing joint 22 and the casing 23 located in the area ①. However, the casing joint 22 and the casing 23 located in the area ① are not subjected to the torque generated by the rotation of the outer bit joint 9 located in the area ③. That is, the outer drill bit 2 and the casing 23 are independent of each other, the casing 23 only provides drilling pressure for the outer drill bit 2 , and the outer drill bit 2 can only perform rotary drilling, but cannot apply rotary torque to the casing 23 . When there is a special situation that the casing 23 is stuck by the broken rock, the casing 23 can also be driven to rotate by the ground equipment to release the stuck without affecting the normal drilling of the outer drill bit 2 .

Further, in conjunction with Figure 2, Figure 3, Figure 10 and Figure 11, it can be seen from the figure that the mud circulation is divided into two paths:

The first situation is: flow out from the inner drill bit 1, flow through the inner drill bit nozzle 102 and the outer drill bit nozzle 202 at the bottom of the outer drill bit 2, enter the annular space formed by the outer drill bit 2 and the hole wall, and finally pass through the outer drill bit joint 9. The mud hole 901 enters the annular space formed by the drill pipe 21 and the casing 23 to complete the overall circulation;

The second situation is: because the outer drill nozzle 202 of the outer drill 2 has multiple layers, a part of the mud flows out from the inner drill 1, flows through the inner drill nozzle 102 and the nozzle 202 at the bottom of the outer drill 2, and enters the outer drill 2 and the hole. The annular space formed by the wall finally enters the annular space formed by the drill pipe 21 and the casing 23 through the mud hole 901 on the outer bit joint 9;

The remaining part flows out from the inner bit 1, passes through the inner bit nozzle 102, enters the annulus formed by the inner bit 1 and the outer bit 2, flows out through the outer bit nozzle (202) on the upper part of the outer bit 2, and enters the outer bit 2 and the hole wall. The formed annular space finally enters the annular space formed by the drill pipe 21 and the casing 23 through the mud hole 901 on the outer bit joint 9 to complete the overall circulation.

The working principle of the present invention:

The invention is a double-impregnated diamond drill bit continuously followed by a casing drilling tool system. The working layer structure of the inner bit and the outer bit adopts a specific high-matrix drill bit independently designed by the research group. The steel body part is to meet the structural requirements of the drilling tool system. Brand new design, the inner drill bit 1 is driven to rotate by the drill rod 21, the outer drill bit 2 is driven to rotate by the inner drill bit 1 through the first transmission key 3 and the second transmission key 4, the inner drill bit 1 provides the drilling pressure through the drill rod 21, and the outer drill bit 2 passes Casing 23 and drill pipe 21 provide the weight on bit. The design of the pressure bearing and the guide bearing in the mechanism can realize the function of independent rotation of the outer drill bit 2 and its upper casing 23 . The drill bit structure adopted by the inner drill bit 1 can effectively avoid the problem of local mud false circulation in the high matrix drill bit, limit the mud circulation path, so that the mud can reach the bottom of the hole, and then cooperate with the outer drill bit 2 to realize the mud circulation and complete the cooling of the drill bit. Cleaning with cuttings at the bottom of the hole. In the actual drilling process, the inner and outer drill bits are impregnated with diamond bits, which have little disturbance to the well wall, and the hole wall is relatively regular. The combination with the high carcass design can greatly improve the drilling depth, thereby increasing the depth of the follow-up pipe and realizing continuous follow-up. The pipe is drilled until the bit life or drilling design requirements are reached. At the same time, due to the non-stop drilling during the drilling process, the casing can be rotated independently and continuously followed up, and the friction between the casing and the hole wall is always dynamic friction. Compared with the static friction generated when the drilling is stopped, it can significantly reduce the energy loss and shorten the Drilling time, improve drilling efficiency.

Claims (5)

1. The utility model provides a two pregnant diamond-impregnated bit are with casing drilling tool system in succession which characterized in that: the drill bit comprises an inner drill bit (1), an outer drill bit (2), a first transmission key (3), a second transmission key (4), an inner drill bit limit (5), an outer drill bit limit (6), a first copper sleeve (7), a second copper sleeve (8), an outer drill bit joint (9), an inner drill bit joint (10), an elastic sheet (11), an inner sealing element (12), an outer sealing element (13), a lower pressure bearing (14), a middle pressure bearing (15), an upper pressure bearing (16), a lower pilot bearing limit (17), an upper pilot bearing limit (18), a pilot bearing (19), an outer drill bit joint limit (20), a drill rod (21), a casing joint (22) and a casing (23);

the upper end of an inner drill bit (1) is fixedly connected with the lower end of an inner drill bit joint (10), the upper end of the inner drill bit joint (10) is fixedly connected with the lower end of a drill rod (21), N first key grooves (101) are circumferentially and uniformly distributed on the outer side of the inner drill bit (1), N is larger than or equal to 1, N second key grooves (501) are circumferentially and uniformly distributed on the inner side of an inner drill bit limit (5), N is larger than or equal to 1, N first transmission keys (3) are fixed between the first key grooves (101) and the second key grooves (501), and N is larger than or equal to 1;

n third key grooves (201) are circumferentially and uniformly distributed on the inner side of the outer drill bit (2), N is larger than or equal to 1, N fourth key grooves (601) are circumferentially and uniformly distributed on the outer side of the outer drill bit limiting block (6), N is larger than or equal to 1, and N second transmission keys (4) are fixed between the third key grooves (201) and the fourth key grooves (601);

n first lugs (502) are circumferentially and uniformly distributed on the outer side of the inner drill bit limit (5), N is larger than or equal to 1, N second lugs (602) are circumferentially and uniformly distributed on the inner side of the outer drill bit limit (6), N is larger than or equal to 1, a first boss (603) is arranged at the bottom of the inner side of the outer drill bit limit (6), the inner drill bit limit (5) and the outer drill bit limit (6) are coaxially and rotatably connected, the first lugs (502) are limited at the upper ends of the first bosses (603), and when the inner drill bit limit (5) rotates, the first lugs (502) are in abutting engagement with the second lugs (602), so that the inner drill bit limit (5) rotates to drive the outer drill bit limit (6) to rotate circumferentially;

the lower end of an outer drill bit joint (9) is fixedly connected with the upper end of an outer drill bit (2), a plurality of slurry holes (901) penetrating into the outer drill bit joint (9) are uniformly distributed on the outer drill bit joint (9) in the circumferential direction, a first threaded connector (902), a first groove (903) and a second groove (904) are further arranged on the outer drill bit joint (9), the outer wall of a first copper sleeve (7) is fixedly connected with the first threaded connector (902) through threads, an elastic sheet (11) is arranged in the second groove (904), an inner sealing element (12) is arranged in the first groove (903), the lower end of an outer drill bit joint limit (20) is fixedly connected with the upper end of the outer drill bit joint (9), an inner drill bit joint (10) is fixedly connected with a second copper sleeve (8), the second copper sleeve (8) is limited at the upper end of the first copper sleeve (7), the first copper sleeve (7) and the second copper sleeve (8) can coaxially rotate, and further the annular gap between the outer drill bit joint (9) and the inner drill bit joint (10) is sealed, the inner diameter of the first copper sleeve (7) is smaller than the outer diameter of the second copper sleeve (8);

the lower end of a sleeve (23) is fixedly connected with the upper end of a sleeve joint (22), the sleeve joint (22) is provided with a third groove (221) and a fourth groove (222), a lower guide bearing limit (17) and an upper guide bearing limit (18) are fixedly connected with the sleeve joint (22), the upper end and the lower end of an inner ring of a guide bearing (19) are respectively pressed on the upper end surface of the lower guide bearing limit (17) and the lower end surface of the upper guide bearing limit (18), an outer ring of the guide bearing (19) is fixedly connected with the inner wall of an outer drill bit joint (9), the lower end surface of the lower guide bearing limit (17) on the upper surface of a lower pressure bearing (14) is tightly connected, the lower surface of a lower pressure bearing (14) is tightly contacted with the upper end surface of an elastic sheet (11), the upper end of an inner sealing element (12) is tightly contacted with the lower end surface of the sleeve joint (22), the lower surface of a middle pressure bearing (15) is tightly contacted with the upper surface of the upper guide bearing limit (18), the upper surface of the middle pressure bearing (15) is in close contact with the lower surface of the inner side of the outer bit joint limit (20), the upper pressure bearing (16) is installed in the third groove (221), the lower surface of the upper pressure bearing (16) is in close contact with the upper surface of the outer side of the outer bit joint limit (20), the outer sealing element (13) is installed in the fourth groove (222), and the outer sealing element (13) is in close contact with the upper surface of the outer side of the outer bit joint limit (20).

2. The dual-impregnated diamond-impregnated drill bit continuous-tracking casing drilling system according to claim 1, wherein: when the sleeve (23) is clamped by broken rocks, the sleeve (23) is driven by ground equipment, so that the sleeve (23) is rotationally unlocked by the characteristic spiral groove structure (24) on the surface of the sleeve (23) in rotation.

3. The dual-impregnated diamond-impregnated drill bit continuous-tracking casing drilling system according to claim 1, wherein: when the first lug (502) on the outer side of the inner drill bit limit (5) is contacted with the second lug (602) on the inner side of the outer drill bit limit (6), the inner drill bit water gap (102) of the inner drill bit (1) is aligned with the outer drill bit water gap (202) of the outer drill bit (2).

4. The dual-impregnated diamond bit continuous-tracking casing drilling system according to any one of claims 1 to 3, wherein: the inner drill bit (1) is an ultrahigh working layer involute water gap diamond-impregnated drill bit.

5. The dual-impregnated diamond bit continuous-tracking casing drilling system according to any one of claims 1 to 3, wherein: the outer drill bit (2) is an integrated cutting tooth diamond-impregnated drill bit.

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