Reverse circulation drilling device

Abstract

The invention belongs to the technical field of well drilling, and particularly relates to a reverse circulation well drilling device which comprises a well mouth reverser and a well bottom reverser. A connecting structure is installed on the outer wall of the wellhead reverser, the connecting structure is used for communicating the wellhead reverser with ground equipment, a liquid outlet is formed in the connecting structure, one end of the wellhead reverser is connected with the ground equipment, and the other end of the wellhead reverser is connected with a double-wall drill rod; one end of the shaft bottom reverser is connected with the full-space converter, and the other end of the shaft bottom reverser is connected with the drill bit; the other end of the full-hole converter is connected with the double-wall drill rod; a nozzle is arranged on the shaft bottom reverser; signals of the MWD directional instrument can be transmitted out of the double-wall drill rod, directional drilling is achieved, and the technical requirement for straightness keeping in the drilling process is met through the supporting performance of the full-hole converter on the well wall.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of drilling technology, and particularly relates to a reverse circulation drilling device. BACKGROUND

[0002] Sichuan shale gas resources are rich, and is one of the core areas of shale gas production of China Petroleum. The surface topography of the area is complex, and the underground water resources are rich. The surface layer pore, fracture and cave are developed, the pressure coefficient is low, the surface drilling well leakage and collapse problem is prominent, the complex accident is frequent, the casing is difficult to enter, the drilling cycle is long, the well hole of multiple wells is scrapped, and the well position is forced to move, which causes great economic loss and restricts the safe and efficient development of shale gas.

[0003] At present, there is no good solution to the serious well leakage problem of shale gas surface drilling in southern Sichuan. The double-wall drill pipe reverse circulation drilling technology is an effective low pressure and negative pressure drilling technology. Compared with the positive circulation drilling technology, it has the advantages of high cuttings carrying efficiency, elimination of annular pressure consumption, reduction of well bottom pressure and reduction of well leakage. It has unique advantages in dealing with large amount of water and serious well leakage problems in the formation, and has been maturely applied in the drilling fields of water wells, geothermal wells and gas discharge wells. It is based on double-wall drill pipe, and drilling fluid is pumped into the well from the annulus of the double-wall drill pipe and cleans the well bottom. The cuttings are carried back to the ground from the inner drill pipe, so that the closed loop circulation of the drilling fluid is realized. However, the MWD directional instrument signal cannot be successfully transmitted from the double-wall drill pipe, so that the while-drilling inclination measurement cannot be carried out, and the directional drilling operation cannot be completed. SUMMARY

[0004] In view of the above problems, the present application provides a reverse circulation drilling device, which comprises a wellhead diverter and a well bottom diverter. A connecting structure is installed on the outer wall of the wellhead diverter, the connecting structure is used to communicate the wellhead diverter with the ground equipment, a liquid outlet is arranged on the connecting structure, one end of the wellhead diverter is connected with the ground equipment, and the other end of the wellhead diverter is connected with a double-wall drill pipe. One end of the well bottom diverter is connected with a full-hole converter, and the other end of the well bottom diverter is connected with a drill bit. The other end of the full-hole converter is connected with the double-wall drill pipe. A nozzle is arranged on the well bottom diverter.

[0005] Further, the wellhead diverter comprises a wellhead diverter main body, a wellhead diverter inner pipe is installed in the wellhead diverter main body, a liquid outlet channel is arranged between the wellhead diverter main body and the wellhead diverter inner pipe, and the liquid outlet channel penetrates through the wellhead diverter main body and the wellhead diverter inner pipe.

[0006] Furthermore, the bottom hole commutator includes a bottom hole commutator body, and a bottom hole commutator inner tube is installed inside the bottom hole commutator body; a liquid inlet channel is provided between the bottom hole commutator body and the bottom hole commutator inner tube, and the liquid inlet channel passes through the bottom hole commutator body and the bottom hole commutator inner tube; the bottom hole commutator body is provided with a nozzle at the position of the liquid inlet channel; the nozzle connects the inside of the bottom hole commutator inner tube and the outside of the bottom hole commutator body; a plug is installed inside the bottom hole commutator inner tube at one end close to the drill bit.

[0007] Furthermore, the eyelet converter includes an eyelet main body; an eyelet inner tube is installed inside the eyelet main body.

[0008] Furthermore, three or more liquid outlet channels are provided, and the plurality of liquid outlet channels are circumferentially arranged between the wellhead diverter body and the wellhead diverter inner tube, and the liquid outlet channels are arranged obliquely along the flow direction of the drilling fluid return.

[0009] Furthermore, the cross-section of the connecting structure is an "I" shape; a sealing assembly is provided at the position where the connecting structure contacts the outer wall of the wellhead diverter body, a bearing assembly is provided between the outer ring of the connecting structure and the outer wall of the wellhead diverter body, and a lifting lug is provided on the outer side wall of the connecting structure.

[0010] Furthermore, there is one or more bottom hole diverters.

[0011] Furthermore, the liquid inlet channel is arranged obliquely along the flow direction of the drilling fluid return; three or more liquid inlet channels and nozzles are provided, and multiple liquid inlet channels are circumferentially arranged between the bottom hole commutator body and the bottom hole commutator inner tube; the distance between the nozzle and the connection position of the bottom hole commutator body and the drill bit is greater than one fifth of the length of the bottom hole commutator body.

[0012] Furthermore, tungsten carbide is sprayed on the plug.

[0013] Furthermore, a valve is provided on the nozzle.

[0014] Furthermore, the plug is conical.

[0015] Beneficial effects

[0016] The beneficial effects of the present invention compared to the prior art are as follows:

[0017] 1. The application is realized by setting the well bottom diverter and the well mouth diverter, the ordinary drill bit can be used to carry out the reverse circulation drilling operation, the MWD directional instrument signal can be transmitted out from the double wall drill pipe by connecting the full hole converter on the well bottom diverter, the directional drilling is realized, and the straightness requirement in the drilling process is met by the supporting property of the full hole converter to the well wall.

[0018] 2. The well mouth converter and the well bottom converter in the application can be used for the reverse circulation drilling, the inner pipe of the well mouth diverter and the inner pipe of the well bottom diverter can be pulled out, the ordinary drill bit and the drill pipe are connected to carry out the positive circulation drilling work.

[0019] 3. The application can also use multiple well bottom diverters to be connected, so as to have multiple nozzles at different height positions to carry out the cuttings backflow work, the cuttings can be dispersed to different positions to be backflowed and discharged, the cuttings are avoided to be concentrated at the same position, and the situation of being blocked in the drilling process is further avoided.

[0020] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. The objects and other advantages of the present application will be realized and achieved by means of the structures particularly pointed out in the description and the claims. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0022] Figure 1 The sectional view of the well mouth diverter in the embodiment of the present application is shown.

[0023] Figure 2 The sectional view of the well mouth diverter in the embodiment of the present application is shown. Figure 1

[0024] Figure 3 The top view of the well mouth diverter in the embodiment of the present application is shown.

[0025] Figure 4 The sectional view of the well bottom diverter in the embodiment of the present application is shown.

[0026] Figure 5 The sectional view of the well bottom diverter in the embodiment of the present application is shown. Figure 4

[0027] Figure 6 ​​A cross-sectional view of the full-hole converter in the embodiment of the present application is shown.

[0028] Figure 7 A connection schematic diagram of the well bottom diverter and the full-hole converter in the embodiment of the present application is shown.

[0029] In the figure, 30, connection structure, 301, liquid outlet; 302, sealing assembly; 303, bearing assembly; 304, lifting lug; 201, nozzle; 202, well bottom diverter main body; 203, well bottom diverter inner tube; 204, liquid inlet channel; 205, plug; 101, well head diverter main body; 102, well head diverter inner tube; 103, liquid outlet channel; 401, full-hole main body; 402, full-hole inner tube. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0031] The present application provides a reverse circulation drilling device, comprising a well head diverter and a well bottom diverter; an outer wall of the well head diverter is provided with a connection structure 30, the connection structure 30 is used for connecting the well head diverter with ground equipment, the connection structure 30 is provided with a liquid outlet 301, one end of the well head diverter is connected with the ground equipment, and the other end of the well head diverter is connected with a double-wall drill rod; one end of the well bottom diverter is connected with a full-hole converter, and the other end of the well bottom diverter is connected with a drill bit; the other end of the full-hole converter is connected with the double-wall drill rod.

[0032] Reference Figure 1 , Figure 4 , Figure 6 and Figure 7 , Figure 1 A cross-sectional view of the well head diverter in the embodiment of the present application is shown. Figure 4 A cross-sectional view of the well bottom diverter in the embodiment of the present application is shown. Figure 6 A cross-sectional view of the full-hole converter in the embodiment of the present application is shown. Figure 7 A connection schematic diagram of the well bottom diverter and the full-hole converter in the embodiment of the present application is shown.

[0033] In the implementation process, the well bottom diverter is connected with a drill bit, the drill bit can be a common drill bit used in the positive circulation drilling, the full-hole converter is inserted into the well bottom diverter, and the double-wall drill rod is connected with the full-hole converter.

[0034] One end of the wellhead diverter is connected with the ground equipment, such as a large drilling machine; the connecting structure 30 on the outer wall of the wellhead diverter is fixed on the drilling machine, so as to ensure the stability of the wellhead diverter during use; the liquid outlet channel 103 on the connecting structure 30 is connected with the circulating pipeline of the wellhead; and then the wellhead diverter is connected with the double-wall drill pipe;

[0035] During the drilling process, the drilling fluid flows out from the drilling machine, flows through the wellhead diverter, the double-wall drill pipe, the full-hole converter, the bottom-hole diverter and the drill bit, and then flows back through the bottom-hole diverter and the liquid outlet 301 and the circulating pipeline for treatment; the full-hole converter is provided with a centralizing strip, so as to improve the supportability to the well wall and meet the technical requirements of the double-wall drill pipe; meanwhile, the MWD directional instrument signal can be transmitted out through the full-hole converter, so that the directional drilling work can be more accurately performed; and the full-hole converter can be disassembled; during the operation process without using the full-hole converter, the full-hole converter can be disassembled, and other tools, such as the drill bit, can continue to be normally used;

[0036] The wellhead diverter and the bottom-hole diverter are arranged, the ordinary drill bit is used for reverse circulation drilling, the full-hole converter is connected with the bottom-hole diverter, the MWD directional instrument signal can be transmitted out from the double-wall drill pipe, directional drilling is realized, and the supportability of the full-hole converter to the well wall meets the technical requirements of hole straightening during drilling.

[0037] In an embodiment of the present application, the wellhead diverter comprises a wellhead diverter body 101, a wellhead diverter inner pipe 102 is arranged in the wellhead diverter body 101, a liquid outlet channel 103 is arranged between the wellhead diverter body 101 and the wellhead diverter inner pipe 102, and the liquid outlet channel 103 penetrates through the wellhead diverter body 101 and the wellhead diverter inner pipe 102.

[0038] In an embodiment of the present application, the bottom-hole diverter comprises a bottom-hole diverter body 202, a bottom-hole diverter inner pipe 203 is arranged in the bottom-hole diverter body 202, a liquid inlet channel 204 is arranged between the bottom-hole diverter body 202 and the bottom-hole diverter inner pipe 203, the liquid inlet channel 204 penetrates through the bottom-hole diverter body 202 and the bottom-hole diverter inner pipe 203, a nozzle 201 is arranged on the bottom-hole diverter body 202 at the position of the liquid inlet channel 204, the nozzle 201 is connected with the inside of the bottom-hole diverter inner pipe 203 and the outside of the bottom-hole diverter body 202, and a plug 205 is arranged at one end of the bottom-hole diverter inner pipe 203 close to the drill bit.

[0039] In an embodiment of the present application, the full-eye converter comprises a full-eye body 401, and a full-eye inner tube 402 is arranged in the full-eye body 401.

[0040] Reference Figure 1 , Figure 4 , Figure 6 and Figure 7 The wellhead diverter, the full-eye converter and the bottom-hole diverter are respectively provided with an inner thread and an outer thread at two ends, which are used for threaded connection with adjacent structures.

[0041] In the implementation process, the wellhead diverter body 101 is connected with the outer tube of the double-wall drill pipe through threading, the inner tube of the double-wall drill pipe is inserted into the wellhead diverter inner tube 102 at one end, and the other end of the inner tube of the double-wall drill pipe is inserted into the full-eye inner tube 402.

[0042] The other end of the outer tube of the double-wall drill pipe is connected with the full-eye body 401 through threading, the other end of the inner tube of the double-wall drill pipe is inserted into the full-eye inner tube 402, the other end of the full-eye body 401 is connected with the bottom-hole diverter body 202 through threading, the other end of the full-eye inner tube 402 is inserted into the bottom-hole diverter inner tube 203, and the other end of the bottom-hole diverter body 202 is connected with the drill bit through threading.

[0043] The wellhead diverter inner tube 102 is inserted into the wellhead diverter body 101, and the connecting part is sealed by a sealing ring; the inner tubes and the bodies of the bottom-hole diverter and the full-eye converter are also connected in the same way.

[0044] The drilling machine makes the drilling fluid flow from between the wellhead diverter body 101 and the wellhead diverter inner tube 102 to between the inner tube and the outer tube of the double-wall drill pipe, and then flow through the full-eye body 401 and the full-eye inner tube 402, and then flow through between the bottom-hole diverter body 202 and the bottom-hole diverter inner tube 203, and then flow out from the water hole of the drill bit.

[0045] Then the cuttings generated in the drilling process flow back through the liquid inlet channel 204 from the nozzle 201 to the inside of the bottom-hole diverter inner tube 203, wherein the drilling fluid and the cuttings flow back from the side of the bottom-hole diverter, so as to avoid the cuttings from being concentrated near the drill bit and causing plugging; the plug 205 blocks the cuttings and the drilling fluid, so as to avoid the backflow of the cuttings and the drilling fluid from the drill bit; the drilling fluid and the cuttings flow into the wellhead diverter inner tube 102 through the full-eye inner tube 402 and the like, and then flow into the space between the wellhead diverter body 101 and the connecting structure 30 through the liquid outlet channel 103, and then converge in the space between the wellhead diverter body 101 and the connecting structure 30, and then flow out from the liquid outlet 301 to the wellhead circulating pipeline, and then the drilling fluid and the cuttings are treated and recycled after flowing out.

[0046] At the same time, when the reverse circulation drilling is not used in the present application, the full-eye inner tube 402 can be pulled out from the full-eye body 401 and connected to an ordinary drill bit and drill pipe to perform positive circulation drilling.

[0047] In one embodiment of the present invention, three or more liquid outlet channels 103 are provided, and the plurality of liquid outlet channels 103 are circumferentially arranged between the wellhead diverter body 101 and the wellhead diverter inner tube 102, and the liquid outlet channels 103 are arranged inclined along the flow direction of the drilling fluid return.

[0048] During implementation, refer to Figure 2 The figure shows the arrangement and distribution of the liquid outlet channels; drilling fluid and cuttings flow to the wellhead through the inner tube 102 of the wellhead diverter; at the wellhead, the flow is divided into three directions, and the three liquid outlet channels 103 simultaneously provide paths for the drilling fluid and cuttings to flow out of the wellhead diverter body 101, and flow out from the liquid outlet channels 103 at the three locations to between the wellhead diverter body 101 and the connecting structure 30; because the outlet positions of the three liquid outlet channels 103 are at different distances from the liquid outlet 301, the drilling fluid and cuttings can be staggered and diverted at the liquid outlet channels 103, avoiding congestion of the drilling fluid and cuttings at the liquid outlet 301;

[0049] At the same time, the liquid outlet channel 103 is tilted along the direction of drilling fluid return, so that the drilling fluid and cuttings can flow out of the wellhead diverter body 101 more smoothly and then flow out through the liquid outlet 301;

[0050] The number, length and inclination angle of the liquid outlet channels 103 can be adjusted according to specific circumstances.

[0051] In one embodiment of the present invention, the cross-section of the above-mentioned connecting structure 30 is an "I" shape; the above-mentioned connecting structure 30 is provided with a sealing assembly 302 at a position where it contacts the outer wall of the above-mentioned wellhead diverter body 101, a bearing assembly 303 is provided between the outer ring of the above-mentioned connecting structure 30 and the outer wall of the above-mentioned wellhead diverter body 101, and a lifting ear 304 is provided on the outer wall of the above-mentioned connecting structure 30.

[0052] refer to Figure 1 and Figure 3 , Figure 1 The seal assembly 302 is provided at the position where the middle connection structure 30 contacts the outer wall of the wellhead diverter body 101, and the bearing assembly 303 is provided at a position at a certain distance from the I-shaped connection structure 30 and the wellhead diverter body 101; Figure 3 A top view of the wellhead diverter in an embodiment of the present invention is shown, and a lifting lug 304 is provided on the side of the connecting mechanism.

[0053] In the implementation process, the lifting lug 304 on the connecting assembly is connected with the lifting ring on the drilling machine, so that the wellhead diverter is stably fixed on the drilling machine, and the sealing assembly 302 is arranged between the inner wall of the connecting structure 30 and the outer wall of the wellhead joint, so that the sealing is performed during the flowing of the drilling fluid and the cuttings from the outlet 301, and the backflow of the drilling fluid is prevented from seeping out between the connecting structure 30 and the wellhead joint.

[0054] The bearing assembly 303 can be a thrust self-aligning roller bearing, which is fixed between the connecting structure 30 and the wellhead diverter main body 101 through the inner and outer rings of the bearing, and the sealing performance can be further improved by arranging an O-shaped ring between the bearing assembly 303 and the wellhead diverter main body 101. The bearing assembly 303 bears the load, thereby improving the stability of the wellhead diverter during operation.

[0055] In an embodiment of the present application, the wellhead diverter is one or more than one.

[0056] In an embodiment of the present application, the liquid inlet channel 204 is arranged along the flow direction of the backflow of the drilling fluid, and the liquid inlet channel 204 and the nozzle 201 are each provided with three or more than three, a plurality of liquid inlet channels 204 are circumferentially arranged between the wellhead diverter main body 202 and the wellhead diverter inner tube 203, and the distance between the nozzle 201 and the position where the wellhead diverter main body 202 is connected with the drill bit is greater than one fifth of the length of the wellhead diverter main body 202.

[0057] In an embodiment of the present application, the nozzle 201 is provided with a valve.

[0058] Reference Figure 4 and Figure 5 , Figure 4 The liquid inlet channel 204 and the nozzle 201 are arranged obliquely, and the nozzle 201 is kept at a certain distance from the position where the drill bit is installed. Figure 5 The sectional view of the wellhead diverter in the present application is shown (three are taken as an example).

[0059] In the implementation process, a plurality of wellhead diverters can be connected, so that a plurality of nozzles 201 at different height positions are used for the backflow of the cuttings, the cuttings can be dispersed to different positions for backflow and discharge, the cuttings are prevented from being concentrated at the same position, and the situation of blockage during drilling is further avoided; the wellhead diverters are inserted between each other; the nozzles 201 on the wellhead diverters are distributed in a tree branch type, and the backflow of the drilling fluid and the cuttings is divided into different levels at different heights.

[0060] The nozzle 201 is inclined to the direction of the drilling fluid backflow, so that the drilling fluid can more smoothly drive the cuttings to flow back to the inside of the well bottom swivel inner tube 203;At the same time, the distance L1 between the setting position of the nozzle 201 and the drill bit and the length L of the well bottom swivel body 202 satisfy the relationship L1>1 / 5L;Therefore, the nozzle 201 is away from the drill bit, thereby further avoiding the cuttings from being concentrated near the drill bit, thereby affecting the operation of the drill bit;

[0061] The relationship between the distance L1 between the setting position of the nozzle 201 and the drill bit and the length L of the well bottom swivel body 202 is that, when the length of the well bottom swivel body 202 is relatively long:

[0062] In order to ensure that the drilling fluid and the cuttings flow back smoothly through the nozzle 201, the proportion of L1 to L should not be too large, that is, the setting position of the nozzle 201 should not be too far away from the drill bit;At this time, it is necessary to satisfy 1 / 2>L1>1 / 5L;

[0063] At the same time, the nozzle 201 is provided with a valve, and the flow rate of the nozzle 201 is controlled through the valve, so that the flow rate of the drilling fluid backflow is adjusted according to different conditions in the drilling process, and the backflow speed of the drilling fluid and the cuttings is ensured while avoiding congestion during the backflow process according to specific conditions, thereby optimizing the drilling process;

[0064] By providing a plurality of liquid inlet channels 204 and nozzles 201, the range of drilling fluid and cuttings backflow is expanded, and a flow channel is more conveniently provided for drilling fluid and cuttings at different positions;The setting of a plurality of liquid inlet channels 204 can also avoid the situation that, when a liquid inlet channel 204 is blocked, the normal operation of the entire well bottom swivel and the entire drilling process is affected;

[0065] At the same time, the amount of drilling fluid and cuttings flowing into the positions near the liquid inlet channels 204 at different positions will be out of sync under different conditions;At this time, the valves on different nozzles can be adjusted to different flow rates to adapt to the current situation.

[0066] In an embodiment of the present application, tungsten carbide is sprayed on the above-mentioned plug 205.

[0067] In an embodiment of the present application, the above-mentioned plug 205 is conical.

[0068] In the implementation process, reference is made to Figure 4 The plug 205 is arranged in the well bottom swivel inner tube 203, and the cuttings will contact the plug 205 during the backflow process through the nozzle 201, thereby causing wear of the plug 205;By spraying tungsten carbide on the plug 205, the tungsten carbide coating has high lightness and high density, and can enhance the corrosion resistance and wear resistance of the plug 205;

[0069] The end cap 205 takes a unique conical design that can withstand greater loads under pressure, allowing for greater stability. The conical head design also has better strength and stiffness, allowing it to withstand higher temperatures and pressures, and prevent leaks.

[0070] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood that modifications can be made to the foregoing embodiments, or equivalents thereof, without departing from the spirit and scope of the inventive subject matter.

Claims

1. A reverse circulation drilling device, characterized in that: The invention comprises a wellhead diverter and a bottom hole diverter; a connection structure (30) is installed on the outer wall of the wellhead diverter, the connection structure (30) is used to connect the wellhead diverter with the ground equipment, a liquid outlet (301) is provided on the connection structure (30), one end of the wellhead diverter is connected to the ground equipment, and the other end of the wellhead diverter is connected to the double-wall drill pipe; one end of the bottom hole diverter is connected to the full eye converter, and the other end of the bottom hole diverter is connected to the drill bit; the other end of the full eye converter is connected to the double-wall drill pipe; a nozzle (201) is provided on the bottom hole diverter.

2. A reverse circulation drilling apparatus as claimed in claim 1 wherein, The wellhead diverter comprises a wellhead diverter body (101), a wellhead diverter inner tube (102) is installed inside the wellhead diverter body (101), a liquid outlet channel (103) is provided between the wellhead diverter body (101) and the wellhead diverter inner tube (102), and the liquid outlet channel (103) passes through the wellhead diverter body (101) and the wellhead diverter inner tube (102).

3. A reverse circulation drilling apparatus as claimed in claim 2 wherein, The bottom hole commutator comprises a bottom hole commutator body (202), a bottom hole commutator inner tube (203) installed inside the bottom hole commutator body (202); a liquid inlet channel (204) is provided between the bottom hole commutator body (202) and the bottom hole commutator inner tube (203), and the liquid inlet channel (204) passes through the bottom hole commutator body (202) and the bottom hole commutator inner tube (203); the bottom hole commutator body (202) is provided with a nozzle (201) at the position of the liquid inlet channel (204); the nozzle (201) communicates the inside of the bottom hole commutator inner tube (203) with the outside of the bottom hole commutator body (202); and a plug (205) is installed inside the bottom hole commutator inner tube (203) at one end close to the drill bit.

4. A reverse circulation drilling apparatus as claimed in claim 3 wherein, The eyelet converter comprises an eyelet main body (401); an eyelet inner tube (402) is installed inside the eyelet main body (401).

5. A reverse circulation drilling apparatus as claimed in claim 4 wherein, There are three or more liquid outlet channels (103), and the plurality of liquid outlet channels (103) are circumferentially arranged between the wellhead diverter body (101) and the wellhead diverter inner tube (102). The liquid outlet channels (103) are arranged obliquely along the direction of return flow of the drilling fluid.

6. A reverse circulation drilling apparatus as claimed in claim 5 wherein, The cross section of the connecting structure (30) is in the shape of an "I" character; a sealing assembly (302) is provided at a position where the connecting structure (30) contacts the outer wall of the wellhead diverter body (101); a bearing assembly (303) is provided between the outer ring of the connecting structure (30) and the outer wall of the wellhead diverter body (101); and a lifting lug (304) is provided on the outer side wall of the connecting structure (30).

7. A reverse circulation drilling apparatus as claimed in claim 6 wherein, There is one or more bottom hole diverters.

8. A reverse circulation drilling apparatus as claimed in claim 7 wherein, The liquid inlet channel (204) is arranged along the flow direction of the drilling fluid return; the liquid inlet channel (204) and the nozzle (201) are each provided with three or more than three liquid inlet channels (204) circumferentially arranged between the bottom hole diverter main body (202) and the bottom hole diverter inner tube (203); the distance between the nozzle (201) and the position where the bottom hole diverter main body (202) is connected with the drill bit is greater than one fifth of the length of the bottom hole diverter main body (202).

9. A reverse circulation drilling apparatus as claimed in claim 8 wherein, The plug (205) is sprayed with tungsten carbide.

10. A reverse circulation drilling apparatus as claimed in claim 9 wherein, The nozzle (201) is provided with a valve.

11. A reverse circulation drilling apparatus as claimed in claim 10 wherein, The plug (205) is conical.

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