CN210768668U

CN210768668U - Gas-lift reverse circulation drilling system

Info

Publication number: CN210768668U
Application number: CN201921686849.3U
Authority: CN
Inventors: 李黔; 张小林; 尹虎; 尹文锋; 杨帆
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2019-10-10
Filing date: 2019-10-10
Publication date: 2020-06-16
Anticipated expiration: 2029-10-10

Abstract

The utility model discloses a gas lift reverse circulation drilling system, it includes well head device, well drilling tool, returns pipeline, gas injection pipeline, drilling fluid injection pipeline and automatic control system. The downhole drilling tool comprises a drill bit, a downhole electromagnetic PWD, a drill collar, a lower single-wall drill pipe, a gas-water mixer, a double-wall drill pipe, an air injection valve and an upper single-wall drill pipe. The gas injection and drilling fluid injection pipeline is provided with an automatic throttle valve, a pressure gauge, a flowmeter and an automatic pressure relief valve. The automatic control system comprises a signal receiver, a computer, a display, a PLC (programmable logic controller) and a parameter input module, and during the gas lift reverse circulation drilling process, the automatic control system monitors the bottom pressure of the well in real time, adjusts the gas injection quantity parameter and the drilling fluid injection parameter and realizes the automatic and accurate control of the bottom pressure. The utility model has the advantages that: the well control risk is reduced by matching with conventional well control equipment at a well mouth; the bottom hole pressure is accurately controlled, and the well leakage and overflow are prevented.

Description

Gas-lift reverse circulation drilling system

Technical Field

The utility model relates to an oil gas probing technical field, especially a gas lift reverse circulation drilling system.

Background

In the drilling process, due to the reasons of unknown underground pressure system, complex geological conditions and the like, lost circulation sometimes occurs, serious leakage even lost circulation occurs, and therefore complex conditions in the well such as overflow, stuck drill, collapse of well wall and the like are caused, a large amount of economic losses are caused, and the environment is possibly polluted. The leak-proof drilling technology is more, including gas drilling technology, foam drilling technology, clear water strong drilling, mud cap drilling technology and the like, and the technologies all have certain limitations: due to the characteristics of the gas drilling technology, the gas drilling technology is limited in application to strata which are high in water yield and easy to collapse; the foam drilling fluid is difficult to recover by the foam drilling technology, and environmental pollution is easily caused; the clear water strong drilling and mud cap drilling technologies are difficult to ensure that all rock debris generated by drilling leaks into the stratum, and the drilling sticking risk is high.

The gas lift reverse circulation well drilling technology is one of leak-proof well drilling technologies, has unique advantages in the aspect of treating serious well leakage problems of low-pressure stratums developing in cracks and karst caves, and has the following main advantages: circulation can be established under the condition of lost return; eliminating the annular pressure loss; the sand carrying efficiency is high. At present, the technology is applied to the drilling fields of water wells, geothermal wells, mines, gas drainage wells and the like, but in the drilling process of the conventional gas lift reverse circulation drilling technology, a well head is opened, a certain well control risk exists, the determination of key construction parameters related to the technology is still in an engineering summary stage, the control of bottom hole pressure is not accurate, the risk of well leakage and overflow exists in the construction process, and risk control measures are lacked when the pressure is too high or a flow passage is blocked.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to solve the difficult problem of lost circulation stratum drilling, provide a gas lift reverse circulation drilling system of lost circulation stratum that reduces lost circulation and overflow, reduces well accuse risk, specially adapted crack and solution cavity and develop.

The purpose of the utility model is realized through the following technical scheme: a gas lift reverse circulation well drilling system comprises a wellhead device, a return outlet pipeline, an in-well drilling tool, an air injection pipeline, a drilling fluid injection pipeline and an automatic control system;

the wellhead device comprises a drilling cross arranged at the top of a wellhead, the top of the drilling cross is sequentially provided with a lifting nipple, a flashboard blowout preventer and a rotary blowout preventer, an annular liquid level monitoring echometer is arranged on a bypass valve on the right side of the rotary blowout preventer, a gas-water isolating pipe is arranged in the lifting nipple, the upper end of the gas-water isolating pipe is flanged outwards and fixedly arranged on the inner wall of the lifting nipple, and the lower end of the gas-water isolating pipe penetrates through the drilling cross and extends into a well;

the return pipeline comprises a top drive, a water hose, a vertical pipe, a sand discharge pipeline and a vibrating screen, wherein the water hose, the vertical pipe and the sand discharge pipeline are sequentially connected between the liquid outlet of the top drive and the inlet end of the vibrating screen;

the downhole drilling tool comprises a drill bit, a downhole electromagnetic PWD, a drill collar, a lower single-wall drill rod, a gas-water mixer, a double-wall drill rod, an air injection valve and an upper single-wall drill rod which are arranged in the well and sequentially connected from bottom to top, wherein the upper single-wall drill rod extends on the drill floor and is connected with the top drive;

the double-wall drill rod comprises an outer pipe and an inner pipe, and the inner pipe is axially arranged in the outer pipe;

the gas injection valve comprises a gas injection valve inner pipe, a gas injection valve outer pipe and a partition plate A, wherein the partition plate A is welded in the gas injection valve outer pipe, a through hole A is formed in the center of the partition plate A, the gas injection valve inner pipe is welded in the through hole A, the upper end of the gas injection valve inner pipe extends upwards and is in threaded connection with the lower end of an upper single-wall drill rod, the lower end of the gas injection valve inner pipe is in threaded connection with the upper end of the inner pipe, the gas injection valve outer pipe is provided with a plurality of side holes A which are positioned below the partition plate A, the gas injection valve outer pipe is in threaded connection with the upper end of the outer pipe, and the gas injection valve moves in;

the gas-water mixer comprises a gas-water mixer inner tube, a gas-water mixer outer tube and a partition B, the partition B is welded in the gas-water mixer outer tube, the center of the partition B is provided with a through hole B, the gas-water mixer inner tube is welded in the through hole B, the gas-water mixer inner tube is provided with a plurality of side holes B positioned above the partition B, the upper end of the gas-water mixer inner tube extends upwards and is in threaded connection with the lower end of the inner tube, the lower end of the gas-water mixer inner tube extends downwards and is in threaded connection with the upper end of a lower single-wall drill rod, the gas-water mixer outer tube is in threaded connection with the lower end of the outer tube, and the gas;

the gas injection pipeline comprises an air compressor, a supercharger and a rotary blowout preventer, and an automatic throttle valve I, a pressure gauge I, a flow meter I and an automatic pressure relief valve I are sequentially connected between a gas outlet of the supercharger and a left side bypass valve of the rotary blowout preventer;

the drilling fluid injection pipeline comprises a mud tank, a mud pump, a kill manifold and a drilling four-way joint, wherein an automatic pressure release valve II, an automatic throttle valve II, a pressure gauge II and a flowmeter II are sequentially connected between the mud pump and the inlet end of the kill manifold, and the mud pump is communicated with the mud tank through a pipeline;

the automatic control system comprises a signal receiver, a display, a parameter input module, a PLC (programmable logic controller) and a computer, wherein the signal receiver, the display, the parameter input module and the PLC are respectively in wired connection with the computer;

the signal receiver is connected with the underground electromagnetic PWD and the annular liquid level monitoring echometer through radio signals, and is connected with the pressure gauge I, the flow meter I, the pressure gauge II and the flow meter II through wired electric signals;

and the PLC is connected with the automatic throttle valve I, the automatic pressure relief valve I, the automatic throttle valve II and the automatic pressure relief valve II through wired electric signals.

The upper end of the gas injection valve and the lower end of the gas-water mixer are equal in diameter to the single-wall drill rod, and the lower end of the gas injection valve and the upper end of the gas-water mixer are equal in diameter to the double-wall drill rod.

Bypass valves are arranged on the left side and the right side of the rotary blowout preventer.

And the kill manifold is connected with the flat valve on the left side of the drilling four-way valve.

The underground electromagnetic PWD and the annular liquid level monitoring echometer have a radio signal transmitting function.

The signal receiver has wireless and wired signal receiving functions.

The utility model has the advantages of it is following:

1. the required equipment can be transformed on the basis of the existing equipment, the field operation is simple, the process conversion is convenient, the drilling is carried out by adopting the gas lift reverse circulation principle, and the method is suitable for the leakage stratum with the developed cracks and karst caves.

2. Gas is injected into the outer pipe of the double-wall drill rod through the rotary blowout preventer and the gas injection valve, the well head uses the single-wall drill rod, the well control equipment of the conventional well head is completely matched, and the well control risk is reduced.

3. In the drilling process, the underground electromagnetic PWD monitors the bottom pressure in real time, and the automatic control system adjusts the gas injection parameters and the drilling fluid injection parameters, so that the bottom pressure can be automatically and accurately controlled, and the well leakage and overflow are prevented.

Drawings

FIG. 1 is a flow chart of an embodiment of the automatic control method for gas lift reverse circulation drilling of the present invention;

FIG. 2 is a schematic connection diagram of the gas injection valve, the double-wall drill pipe and the gas-water mixer;

FIG. 3 is a schematic representation of the flow of fluid within a well drilling tool;

FIG. 4 is a schematic view of the structure of the separator;

FIG. 5 is a schematic structural view of a gas-water separation pipe;

in the figure, 1-drilling four-way joint, 2-lifting short joint, 3-ram blowout preventer, 4-rotating blowout preventer, 5-top drive, 6-hose, 7-vertical pipe, 8-vibrating screen, 9-drill bit, 10-downhole electromagnetic PWD, 11-drill collar, 12-lower single-wall drill pipe, 13-gas-water mixer, 14-double-wall drill pipe, 15-gas injection valve, 16-upper single-wall drill pipe, 17-gas injection valve inner pipe, 18-gas injection valve outer pipe, 19-side hole A, 20-baffle A, 21-inner pipe, 22-outer pipe, 23-gas-water mixer inner pipe, 24-side hole B, 25-gas-water mixer outer pipe, 26 baffle B, 27-air compressor, 28-supercharger, 29-automatic throttle valve I, 30-pressure gauge I, 31-a flow meter I, 32-an automatic pressure relief valve I, 33-a mud tank, 34-an automatic pressure relief valve II, 35-an automatic throttle valve II, 36-a pressure gauge II, 37-a flow meter II, 38-a kill-job manifold, 39-an automatic control system, 40-an explicit device, 41-a computer, 42-a PLC controller, 43-a signal receiver, 44-a parameter input module, 45-a gas-water isolation pipe, 46-a mud pump, 47-a bypass valve, 48-an echo instrument, 49-a sand discharge pipeline, 50-a flat valve and 51-a well.

Detailed Description

The invention will be further described with reference to the accompanying drawings, without limiting the scope of protection to the following:

as shown in fig. 1 to 5, a gas lift reverse circulation well drilling system comprises a wellhead device, a return pipeline, a drilling tool in a well, an air injection pipeline, a drilling fluid injection pipeline and an automatic control system 39;

the well head device is including setting up in the well drilling cross 1 at well head top, and well drilling cross 1's top is provided with rising nipple joint 2, flashboard preventer 3 and rotatory preventer 4 in order, be provided with annular space liquid level monitoring echometer 48 on the bypass valve of 4 right sides of rotatory preventer, rising is provided with air water isolation pipe 45 in the nipple joint 2, and the upper end of air water isolation pipe 45 is outside turn-ups and set firmly on rising nipple joint 2's inner wall, and the lower tip of air water isolation pipe 45 runs through well drilling cross 1 and extends 51 in the well.

The return pipeline comprises a top drive 5, a water hose 6, a vertical pipe 7, a sand discharge pipeline 49 and a vibrating screen 8, wherein the water hose 6, the vertical pipe 7 and the sand discharge pipeline 49 are sequentially connected between the liquid outlet of the top drive 5 and the inlet end of the vibrating screen 8; the downhole drilling tool comprises a drill bit 9, a downhole electromagnetic PWD10, a drill collar 11, a lower single-wall drill rod 12, a gas-water mixer 13, a double-wall drill rod 14, a gas injection valve 15 and an upper single-wall drill rod 16 which are arranged in a well 51 and sequentially connected from bottom to top, wherein the upper single-wall drill rod 16 extends on a drill floor and is connected with a top drive 5.

The double-wall drill rod 14 comprises an outer pipe 22 and an inner pipe 21, wherein the inner pipe 21 is axially arranged in the outer pipe 22; the gas injection valve 15 comprises a gas injection valve inner tube 17, a gas injection valve outer tube 18 and a partition plate A20, the partition plate A20 is welded in the gas injection valve outer tube 18, the center of the partition plate A20 is provided with a through hole A, the gas injection valve inner tube 17 is welded in the through hole A, the upper end of the gas injection valve inner tube 17 extends upwards and is in threaded connection with the lower end of an upper single-wall drill rod 16, the lower end of the gas injection valve inner tube 17 is in threaded connection with the upper end of an inner tube 21, the gas injection valve outer tube 18 is provided with a plurality of side holes A19 positioned below the partition plate A20, the gas injection valve outer tube 18 is in threaded connection with the upper end of an outer tube 22, and the gas injection valve 15 moves in the; gas-water mixer 13 includes gas-water mixer inner tube 23, gas-water mixer outer tube 25 and baffle B26, baffle B26 welds in gas-water mixer outer tube 25, through-hole B has been seted up at baffle B26 center, has welded gas-water mixer inner tube 23 in the through-hole B, has seted up a plurality of side holes B24 that are located baffle B26 top on the gas-water mixer inner tube 23, the upper end of gas-water mixer inner tube 23 upwards extend and with the lower tip threaded connection of inner tube 21, the tip downwardly extending of gas-water mixer inner tube 23 and with the upper end threaded connection of lower single-walled drilling rod 12, gas-water mixer outer tube 25 threaded connection is in the lower tip of outer tube 22, and gas-water mixer 13 during operation sinks under the annular space liquid level.

The gas injection pipeline comprises an air compressor 27, a supercharger 28 and a rotary blowout preventer 4, and an automatic throttle valve I29, a pressure gauge I30, a flow meter I31 and an automatic pressure relief valve I32 are sequentially connected between the gas outlet of the supercharger 28 and a left side bypass valve of the rotary blowout preventer 4; the drilling fluid injection pipeline comprises a mud tank 33, a mud pump 46, a kill-job manifold 38 and a drilling four-way joint 1, wherein an automatic pressure relief valve II34, an automatic throttle valve II35, a pressure gauge II36 and a flow meter II37 are sequentially connected between the mud pump 46 and the inlet end of the kill-job manifold 38, and the mud pump 46 is communicated with the mud tank 33 through a pipeline.

The automatic control system 39 comprises a signal receiver 43, a display 40, a parameter input module 44, a PLC controller 42 and a computer 41, wherein the signal receiver 43, the display 40, the parameter input module 44 and the PLC controller 42 are respectively connected with the computer 41 by wires.

The signal receiver 43 is connected with the underground electromagnetic PWD10 and the annular liquid level monitoring echometer 48 through radio signals, and the signal receiver 43 is connected with the pressure gauge I30, the flow meter I31, the pressure gauge II36 and the flow meter II37 through wired electric signals; the PLC 42 is connected with the automatic throttle valve I29, the automatic pressure relief valve I32, the automatic throttle valve II35 and the automatic pressure relief valve II34 through wired electric signals. The upper end of the gas injection valve 15 and the lower end of the gas-water mixer 13 are equal in diameter to the single-wall drill rod, and the lower end of the gas injection valve 15 and the upper end of the gas-water mixer 13 are equal in diameter to the double-wall drill rod 14. And bypass valves are arranged on the left side and the right side of the rotary blowout preventer 4. The kill manifold 38 is connected to the plate valve on the left side of the four-way drilling 1. The downhole electromagnetic PWD10 and the annulus level monitoring echometer 48 have radio signal transmission capabilities. The signal receiver 43 has a wireless and wired signal receiving function.

As shown in fig. 1 to 3, the automatic control method of the gas lift reverse circulation drilling system comprises the following steps:

s1, setting pressure relief thresholds of an automatic pressure relief valve I32 and an automatic pressure relief valve II34 on a parameter input module 44 of the automatic control system 39 according to the pressure bearing capacity of well head equipment, an air injection pipeline and a drilling fluid injection pipeline, and inputting formation pore pressure, formation collapse pressure, formation leakage pressure and formation fracture pressure on the parameter input module 44 according to adjacent well data and prediction data;

s2, the gas lift reverse circulation well drilling comprises the following specific steps:

s21, starting the air compressor 27 and the mud pump 46, driving the upper single-wall drill rod 16 to rotate through the top drive 5, driving the double-wall drill rod 14 to rotate through the upper single-wall drill rod 16, driving the lower single-wall drill rod 12, the drill collar 11 and the drill bit 9 to rotate through the double-wall drill rod 14, and drilling the drill bit 9 into the stratum;

s22, an air compressor 27 generates compressed gas, the compressed gas sequentially passes through a supercharger 28, an automatic throttle valve I29, a pressure gauge I30, a flow meter I31 and a bypass valve 47 to enter the rotary blowout preventer 4, high-pressure gas sequentially passes through a side hole A19, the annular space of an inner pipe 17 of an air injection valve and an outer pipe 18 of the air injection valve, the annular space of a double-wall drill pipe 14, the annular space of an inner pipe 23 of an air-water mixer and an outer pipe 25 of the air-water mixer and a side hole B24 to enter the inner pipe 23 under air pressure, as shown by a single arrow in figure 3, the flowing direction of the gas is shown, and the drilling fluid in the inner;

s23, a mud pump 46 pumps out the drilling fluid in a mud tank 33, the drilling fluid enters the drilling four-way joint 1 through an automatic throttle valve II35, a pressure gauge II36, a flowmeter II37, a kill manifold 38 and a flat valve 50 in sequence under the action of pumping pressure, the drilling fluid is blocked by a gas-water isolation pipe 45 and falls to the bottom of a well along the annular space between the well wall and the gas-water isolation pipe 45 and the annular space between the well wall and an outer pipe 22, and then the drilling fluid enters the inner pipe 21 of the double-wall drill pipe through a drill bit 9, a drill collar 11, a lower single-wall drill pipe 12 and a through hole B in sequence under pressure, the double-arrow in the figure 3 shows the flowing direction of the drilling fluid, and the three-;

s24, enabling the lifted drilling fluid to sequentially pass through the double-wall drill pipe inner pipe 21, the through hole A, the upper single-wall drill pipe 16, the hose 6, the stand pipe 7 and the sand discharge pipeline 49 and finally enter the vibrating screen 8, separating and then entering the slurry tank 33, and finally completing gas-lift reverse circulation drilling, so that the injected drilling fluid is prevented from flowing into gaps or karst caves, and further the waste of the drilling fluid is avoided, therefore, the reverse circulation drilling mode is particularly suitable for leakage strata with cracks and karst caves developed;

s3, in the drilling process of the step S2, gas injection parameters and drilling fluid injection parameters are monitored in real time through a flow meter I31, a pressure meter I30, a flow meter II37 and a pressure meter II36, the height of the liquid level of the annulus is monitored in real time through an annulus liquid level monitoring echo instrument 48, and drilling parameters such as bottom pressure, drilling fluid flow and the like are monitored in real time through bottom hole electromagnetic MWD 10;

s4, in the drilling process of the step S2, a bottom hole safety pressure window is calculated through the computer 41, whether bottom hole pressure monitored by the PWD10 in real time is in the safety pressure window is judged, if not, new gas injection parameters and drilling fluid injection parameters are calculated, signals are transmitted to the PLC 42, the automatic throttle valve I29 and the automatic throttle valve II35 are controlled to adjust, gas injection quantity and drilling fluid discharge quantity are changed, bottom hole pressure is kept in the range of the safety pressure window, and overflow and well leakage are prevented;

s5, in the drilling process of the step S2, gas injection pressure and drilling fluid injection pressure are monitored in real time through the automatic control system 39, when the pressure exceeds a pressure relief threshold value, the PLC 42 controls the automatic pressure relief valve I32 and the automatic pressure relief valve II34 to relieve the pressure, and high-pressure-holding damage caused by channel blockage and the like is prevented;

s6, synchronously displaying well drilling parameters such as a well bottom safety pressure window, an annular space liquid level height, well bottom pressure, gas injection parameters, drilling fluid injection parameters, an automatic throttle valve opening degree, an automatic pressure relief valve switching state and the like through the display 40 in the well drilling process of the step S2, and controlling gas lift reverse circulation well drilling dynamics in real time.

The above description is not intended to limit the present invention in any way, and the present invention has been disclosed in the above embodiments, but is not intended to be limited thereto, and any person skilled in the art can make some changes or modify equivalent embodiments with equivalent changes when using the technical content disclosed above without departing from the technical scope of the present invention.

Claims

1. A gas lift reverse circulation drilling system characterized in that: the system comprises a wellhead device, a return pipeline, an in-well drilling tool, an air injection pipeline, a drilling fluid injection pipeline and an automatic control system (39);

the wellhead device comprises a drilling cross joint (1) arranged at the top of a wellhead, the top of the drilling cross joint (1) is sequentially provided with a lifting nipple (2), a ram blowout preventer (3) and a rotary blowout preventer (4), an annular liquid level monitoring echometer (48) is arranged on a bypass valve on the right side of the rotary blowout preventer (4), a gas-water isolating pipe (45) is arranged in the lifting nipple (2), the upper end of the gas-water isolating pipe (45) is flanged outwards and fixedly arranged on the inner wall of the lifting nipple (2), and the lower end of the gas-water isolating pipe (45) penetrates through the drilling cross joint (1) and extends into a well (51);

the return pipeline comprises a top drive (5), a water hose (6), a vertical pipe (7), a sand discharge pipeline (49) and a vibrating screen (8), wherein the water hose (6), the vertical pipe (7) and the sand discharge pipeline (49) are sequentially connected between the liquid outlet of the top drive (5) and the inlet end of the vibrating screen (8);

the downhole drilling tool comprises a drill bit (9), a downhole electromagnetic PWD (10), a drill collar (11), a lower single-wall drill rod (12), a gas-water mixer (13), a double-wall drill rod (14), an air injection valve (15) and an upper single-wall drill rod (16), wherein the drill bit (9), the downhole electromagnetic PWD, the drill collar (11), the lower single-wall drill rod, the gas-water mixer (13), the double-wall drill rod (14), the air injection valve (15) and the upper single-wall drill rod (16) are arranged in;

the double-wall drill rod (14) comprises an outer pipe (22) and an inner pipe (21), and the inner pipe (21) is arranged in the outer pipe (22) along the axial direction;

the gas injection valve (15) comprises a gas injection valve inner tube (17), a gas injection valve outer tube (18) and a partition plate A (20), the partition plate A (20) is welded in the gas injection valve outer tube (18), the center of the partition plate A (20) is provided with a through hole A, the gas injection valve inner tube (17) is welded in the through hole A, the upper end of the gas injection valve inner tube (17) extends upwards and is in threaded connection with the lower end of an upper single-wall drill rod (16), the lower end of the gas injection valve inner tube (17) is in threaded connection with the upper end of an inner tube (21), the gas injection valve outer tube (18) is provided with a plurality of side holes A (19) positioned below the partition plate A (20), the gas injection valve outer tube (18) is in threaded connection with the upper end of the outer tube (22), and the gas injection valve (15) moves in the range of a gas;

the gas-water mixer (13) comprises a gas-water mixer inner tube (23), a gas-water mixer outer tube (25) and a partition plate B (26), the partition plate B (26) is welded in the gas-water mixer outer tube (25), a through hole B is formed in the center of the partition plate B (26), the gas-water mixer inner tube (23) is welded in the through hole B, a plurality of side holes B (24) located above the partition plate B (26) are formed in the gas-water mixer inner tube (23), the upper end of the gas-water mixer inner tube (23) extends upwards and is in threaded connection with the lower end of the inner tube (21), the lower end of the gas-water mixer inner tube (23) extends downwards and is in threaded connection with the upper end of the lower single-wall drill rod (12), the gas-water mixer outer tube (25) is in threaded connection with the lower end of the outer tube (22), and the gas-water;

the gas injection pipeline comprises an air compressor (27), a supercharger (28) and a rotary blowout preventer (4), and an automatic throttle valve I (29), a pressure gauge I (30), a flow meter I (31) and an automatic pressure relief valve I (32) are sequentially connected between a gas outlet of the supercharger (28) and a left side bypass valve of the rotary blowout preventer (4);

the drilling fluid injection pipeline comprises a mud tank (33), a mud pump (46), a kill manifold (38) and a drilling four-way joint (1), wherein an automatic pressure release valve II (34), an automatic throttle valve II (35), a pressure gauge II (36) and a flowmeter II (37) are sequentially connected between the mud pump (46) and the inlet end of the kill manifold (38), and the mud pump (46) is communicated with the mud tank (33) through a pipeline;

the automatic control system (39) comprises a signal receiver (43), a display (40), a parameter input module (44), a PLC (programmable logic controller) controller (42) and a computer (41), wherein the signal receiver (43), the display (40), the parameter input module (44) and the PLC controller (42) are respectively in wired connection with the computer (41);

the signal receiver (43) is connected with the downhole electromagnetic PWD (10) and the annular liquid level monitoring echometer (48) through radio signals, and the signal receiver (43) is connected with the pressure gauge I (30), the flow meter I (31), the pressure gauge II (36) and the flow meter II (37) through wired electric signals;

and the PLC (42) is connected with the automatic throttle valve I (29), the automatic pressure relief valve I (32), the automatic throttle valve II (35) and the automatic pressure relief valve II (34) through wired electric signals.

2. A gas lift reverse circulation drilling system according to claim 1 wherein: the upper end of the air injection valve (15) and the lower end of the air-water mixer (13) are equal in diameter to the single-wall drill rod, and the lower end of the air injection valve (15) and the upper end of the air-water mixer (13) are equal in diameter to the double-wall drill rod (14).

3. A gas lift reverse circulation drilling system according to claim 1 wherein: bypass valves are arranged on the left side and the right side of the rotary blowout preventer (4).

4. A gas lift reverse circulation drilling system according to claim 1 wherein: and the kill manifold (38) is connected with a flat valve on the left side of the drilling four-way valve (1).

5. A gas lift reverse circulation drilling system according to claim 1 wherein: the downhole electromagnetic PWD (10) and the annular liquid level monitoring echometer (48) have a radio signal transmitting function.

6. A gas lift reverse circulation drilling system according to claim 1 wherein: the signal receiver (43) has wireless and wired signal receiving functions.