A well bottom lifting and assisting circulation reverse circulation drilling well control system

Abstract

The application discloses a well bottom lifting and assisting reverse circulation drilling well control system, and relates to the technical field of oil and gas drilling and drilling engineering. The well bottom lifting and assisting reverse circulation drilling well control system comprises a circulating mud control system for controlling drilling fluid pumping and returning, a large annular liquid supplementing system for balancing well bottom pressure and carrying out well killing operation, and a control terminal connected with the circulating mud control system and the large annular liquid supplementing system. The control terminal controls the operation of the circulating mud control system and the large annular liquid supplementing system to realize positive circulation drilling, reverse circulation drilling, overflow treatment, well closing treatment and well leakage treatment. The drilling fluid circulation system has multiple bypass pipelines, can realize positive and reverse circulation drilling, can realize early overflow monitoring by monitoring the flow and pressure of the drilling fluid pumping channel, the drilling fluid returning channel and the casing annulus, and can improve the well control capacity. The structure is relatively simple, and can deal with downhole complex conditions such as well leakage and overflow in reverse circulation drilling.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas drilling and drilling engineering technology, and more particularly to a well bottom lifting and cleanup reverse circulation drilling well control system, which can be used for well closure, control of inflow and outflow, adjustment of annular heavy slurry height during double-pipe reverse circulation drilling, so as to achieve the effects of closing the flow passage, regulating the well bottom pressure and improving the cleanup capacity. BACKGROUND

[0002] Reverse circulation drilling technology has important application value in the fields of exploration sampling, oil and gas and mineral exploitation, hydrological drilling, engineering construction and the like. After years of field tests and engineering applications, reverse circulation drilling technology has shown advantages such as reduction of repeated breaking of cuttings, maintenance of wellbore cleanliness, protection of wellbore and reservoir, improvement of drilling efficiency, realization of drilling in lost circulation formation, saving of drilling fluid consumption and reduction of drilling cost, and has good development prospects. At present, pump suction reverse circulation drilling technology, gas lifting reverse circulation drilling technology and full well reverse circulation drilling technology have been formed.

[0003] Double-pipe reverse circulation drilling technology adopts double-pipe (double-wall drill pipe or double-pipe continuous pipe), high-pressure drilling fluid is injected into the annulus between the inner pipe and the outer pipe of the double-pipe by a drilling pump through a high-pressure manifold, and then sequentially passes through a lifting pump, a downhole tool pipe string, a drill bit, a well bottom, and then returns to the wellhead from the well bottom through the lifting pump and the inner pipe of the double-pipe. The downhole lifting pump can reduce the well bottom pressure and offset the increased friction resistance from the upward return of the inner pipe in reverse circulation drilling. By controlling the drilling fluid discharge and the wellhead back pressure, the well bottom pressure can be effectively regulated. Reverse circulation drilling technology has great differences from conventional drilling technology in system composition and process scheme, resulting in that the existing conventional drilling well control process scheme and equipment cannot be directly applied, and the oil and gas well pressure cannot be effectively controlled, and it is difficult to deal with complex downhole conditions.

[0004] In order to improve the well control capability of double-pipe reverse circulation drilling technology, it is necessary to design a well control system for double-wall drill pipe well bottom lifting and cleanup reverse circulation drilling, so as to regulate and switch the pressure of the three passages of the water eye of the inner pipe of the double-pipe, the annulus between the inner pipe and the outer pipe of the double-pipe and the wellbore annulus, so as to deal with complex downhole conditions. SUMMARY

[0005] To overcome the shortcomings of the existing technology, this invention discloses a bottom-hole lift-assisted drainage reverse circulation drilling well control system. This invention allows switching between forward and reverse circulation drilling processes via a flat plate valve assembly. The bottom-hole lift-assisted drainage mechanism of this invention solves the problem of insufficient downhole mud lift power during mud reverse circulation, enabling the suction of drilling fluid from the lower part of the tool while simultaneously pushing the upper part upwards, thereby promoting the establishment of internal tubing return and filling the gap in mud reverse circulation technology lacking downhole power tools. By changing the discharge rate and adjusting the throttle valve opening, in conjunction with the bottom-hole lift-assisted drainage mechanism, this invention can control the inflow and outflow rates, adjust the annular heavy mud height, and achieve the purpose of regulating bottom-hole pressure. This invention simultaneously closes the wellbore annulus, drill string outer tubing annulus, and drill string inner tubing water holes by closing the drill pipe plug valve, annular check valve, and one-way check valve. This invention takes corresponding measures to regulate bottom-hole pressure and restore normal drilling operation according to different complex downhole conditions, such as well leakage and overflow.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A bottom-hole lift-assisted reverse circulation drilling well control system includes:

[0008] A circulating mud control system for controlling the pumping in and out of drilling fluid;

[0009] A large annular fluid replenishment system used to balance bottom hole pressure and perform well control operations;

[0010] The control terminal is connected to the circulating mud control system and the annulus fluid replenishment system. The control terminal controls the operation of the circulating mud control system and the annulus fluid replenishment system to perform forward circulation drilling, reverse circulation drilling, overflow treatment, shut-in treatment, and lost circulation treatment.

[0011] Preferably, the circulating mud control system includes, in sequence, a drill pipe stop valve, a No. 1 flat plate valve, a drilling fluid return pressure gauge, a drilling fluid return flow meter, a drilling fluid return throttle valve, a drilling fluid solids control device, a mud pit, a drilling pump, a drilling fluid pump inflow meter, a drilling fluid pump inflow pressure gauge, and a No. 4 flat plate valve, all connected by pipelines. The pipelines connected to the drill pipe stop valve and the No. 4 flat plate valve are both connected to the top drive adapter at the top of the double-layer pipe.

[0012] Preferably, a first pipeline is provided between the pipeline at the rear end of the drill pipe plug valve and the pipeline at the rear end of the drilling fluid pump inlet pressure gauge, and a second flat valve is provided on the first pipeline; a second pipeline is provided between the pipeline at the rear end of the first flat valve and the pipeline at the rear end of the fourth flat valve, and a third flat valve is provided on the second pipeline.

[0013] Preferably, the lower part of the double-layer pipe is inserted into the casing, the double-layer pipe is provided with a downhole lifting and assisting mechanism, a one-way check valve and a ring-shaped one-way valve connected with the casing, and the top end of the casing is provided with a surface blowout preventer group.

[0014] Preferably, the large annular space liquid supplementing system comprises, in sequence through pipelines, a liquid supplementing system pressure gauge, a No. 5 flat valve, a No. 1 one-way valve, a No. 1 liquid supplementing system flow meter, a liquid supplementing pump, a liquid supplementing tank, a liquid supplementing system throttle valve, a No. 2 one-way valve and a No. 2 liquid supplementing system flow meter, the pipeline connected with the liquid supplementing system pressure gauge is connected to the casing, and the pipeline connected with the No. 2 liquid supplementing system flow meter is connected to the pipeline between the No. 5 flat valve and the No. 1 one-way valve.

[0015] Preferably, the control terminal acquires data of the drilling fluid pump-in flow meter, the drilling fluid pump-in pressure gauge, the drilling fluid pump-out flow meter, the drilling fluid pump-out pressure gauge, the liquid supplementing system pressure gauge, the No. 1 liquid supplementing system flow meter and the No. 2 liquid supplementing system flow meter in real time.

[0016] Preferably, the control terminal judges the downhole working condition through comparative analysis of the drilling fluid pump-in flow and the drilling fluid pump-out flow.

[0017] When the drilling fluid pump-in flow is equal to the drilling fluid pump-out flow, it belongs to normal drilling working condition.

[0018] When the drilling fluid pump-in flow is less than the drilling fluid pump-out flow, overflow condition occurs in the downhole, and bottom hole pressure reduction control or well killing and well closing measures need to be taken.

[0019] When the drilling fluid pump-in flow is greater than the drilling fluid pump-out flow, well leakage condition occurs in the downhole, and bottom hole pressure increase control needs to be taken.

[0020] Preferably, the control terminal controls the opening degree of the drilling fluid pump-out throttle valve and the liquid supplementing system throttle valve, and controls the opening and closing of the drilling pump, the liquid supplementing pump, the No. 1 flat valve, the No. 2 flat valve, the No. 3 flat valve, the No. 4 flat valve and the No. 5 flat valve according to the downhole working condition.

[0021] 1. Positive circulation drilling working condition

[0022] Preferably, the positive circulation drilling working condition comprises the following steps.

[0023] Step S11, closing the No. 2 flat valve and the No. 3 flat valve.

[0024] Step S12, opening the No. 1 flat valve and the No. 4 flat valve.

[0025] Step S13, opening the drilling pump.

[0026] Step S14, starting positive circulation drilling.

[0027] 2. Reverse circulation drilling working condition

[0028] Preferably, the reverse circulation drilling working condition comprises the following steps:

[0029] Step S21, close the first flat valve and the fourth flat valve;

[0030] Step S22, open the second flat valve and the third flat valve;

[0031] Step S23, open the drilling pump;

[0032] Step S24, start reverse circulation drilling.

[0033] 3. Overflow treatment working condition

[0034] Preferably, the overflow treatment working condition comprises: when the overflow amount is small, adjusting by increasing the bottom hole pressure; when the overflow amount is large, adjusting by killing well.

[0035] Preferably, when the overflow amount is small, adjusting by increasing the bottom hole pressure, comprises the following steps:

[0036] Step S31, reduce the opening degree of the drilling fluid return throttle valve;

[0037] Step S32, close the first flat valve and the fourth flat valve;

[0038] Step S33, open the second flat valve and the third flat valve;

[0039] Step S34, open the drilling pump;

[0040] Step S35, inject high-density drilling fluid into the annulus of the drill pipe outer tube;

[0041] Step S36, when the overflow amount is 0, stop the action, and realize well control.

[0042] Preferably, when the annulus drilling fluid still cannot balance the formation pressure, further comprising:

[0043] Step S38, open the fifth flat valve;

[0044] Step S39, open the liquid supplementing pump;

[0045] Step S40, inject high-density mud into the wellbore annulus, increase the annulus heavy mud column height, and further increase the bottom hole pressure.

[0046] Preferably, when the overflow amount is large, adjusting by killing well, comprises: low-pressure low-permeability formation one-time killing method, low-pressure low-permeability formation step-by-step killing method, and high-pressure high-permeability formation killing method.

[0047] Preferably, the low-pressure low-permeability formation one-time killing method comprises the following steps:

[0048] Step S41, close the second flat plate valve, close the fourth flat plate valve;

[0049] Step S42, open the first flat plate valve, open the third flat plate valve, and open the drilling pump;

[0050] Step S43, open the fifth flat plate valve;

[0051] Step S44, simultaneously inject the well killing fluid into the inner tube water hole and the drilling tool annulus, and top up the annulus to the throttle manifold for spouting;

[0052] Step S45, when the overflow amount is 0, stop the action, and realize well control.

[0053] Preferably, the low-pressure and low-permeability formation step-by-step well killing method comprises the following steps:

[0054] First step, first kill the wellbore annulus:

[0055] Step S51, open the fifth flat plate valve;

[0056] Step S52, close the first flat plate valve and the fourth flat plate valve;

[0057] Step S53, open the second flat plate valve and the third flat plate valve;

[0058] Step S54, open the drilling pump;

[0059] Step S55, when the casing pressure drop is 0, close the fifth flat plate valve, and thus complete the wellbore annulus part of the well killing;

[0060] Second step, kill the inner tube water hole:

[0061] Step S61, close the second flat plate valve and the third flat plate valve;

[0062] Step S62, open the first flat plate valve and the fourth flat plate valve;

[0063] Step S63, close the fifth flat plate valve;

[0064] Step S64, open the drilling pump;

[0065] Step S65, until the inner tube water hole shut-in pressure drop is 0, and thus complete the entire well killing process.

[0066] Preferably, the high-pressure and high-permeability formation well killing method comprises the following steps:

[0067] Step S71, close the second flat plate valve, close the fourth flat plate valve;

[0068] Step S72, open the first flat plate valve, open the third flat plate valve, and open the drilling pump;

[0069] Step S73, open the No. 5 flat valve;

[0070] Step S74, open the liquid supplementing pump;

[0071] Step S75, simultaneously inject the kill fluid through the three channels, and all the mud is injected into the formation.

[0072] 4. Shut-in treatment working condition

[0073] Preferably, the shut-in treatment working condition comprises the following steps:

[0074] Step S81, manually close the drill pipe cock valve to close the inside pipe borehole of the drilling tool;

[0075] Step S82, close the mud-driven bottom hole annular check valve and the check valve to close the annulus of the outside pipe of the drilling tool;

[0076] Step S83, close the No. 5 flat valve;

[0077] Step S84, close the ground blowout preventer group.

[0078] 5. Loss treatment working condition

[0079] Preferably, the loss treatment working condition comprises the following steps:

[0080] When the loss amount is small, the bottom hole pressure is adjusted by being reduced:

[0081] Step S91, close the No. 1 flat valve and the No. 4 flat valve;

[0082] Step S92, open the No. 2 flat valve and the No. 3 flat valve;

[0083] Step S93, open the drilling pump;

[0084] Step S94, increase the displacement, and the mud drives the downhole lifting and assisting mechanism to work;

[0085] Step S95, when the loss amount is 0, stop the action, and realize well control.

[0086] Advantages of the present application:

[0087] In the well bottom lifting and assisting reverse circulation drilling well control system provided by the present application, the drilling fluid circulation system has multiple bypass pipelines, can realize positive and reverse circulation drilling, can realize early overflow monitoring by monitoring the flow and pressure of the drilling fluid pump-in channel, the drilling fluid return channel and the casing annulus, and can improve the well control ability.

[0088] The well bottom lifting and assisting reverse circulation drilling well control system provided by the application can automatically supplement and return drilling fluid to the annulus according to the well bottom pressure, and the drilling fluid is supplemented into the annulus when the well bottom pressure is small, and the drilling fluid is returned to the annulus when the well bottom pressure is large.

[0089] The well bottom lifting and assisting reverse circulation drilling well control system provided by the application has a simple structure and can cope with downhole complex conditions such as lost circulation and overflow in reverse circulation drilling. BRIEF DESCRIPTION OF DRAWINGS

[0090] Figure 1 It is a schematic diagram of the well bottom lifting and assisting reverse circulation drilling well control system of the application.

[0091] Figure 2 It is a positive and reverse circulation drilling and well closing control method of the application.

[0092] Figure 3 It is an overflow and lost circulation well control control method of the application.

[0093] Figure 4 It is a well bottom pressure regulation scheme of the application by injecting light slurry and light slurry return outlet throttling valve.

[0094] Figure 5 It is a well bottom pressure regulation scheme of the application by injecting heavy slurry.

[0095] Figure 6 It is a low-pressure and low-permeability formation one-time well killing scheme of the application.

[0096] Figure 7 It is a wellbore annulus first well killing schematic diagram in the low-pressure and low-permeability formation step-by-step well killing scheme of the application.

[0097] Figure 8 It is a pressure inner tube water hole schematic diagram in the low-pressure and low-permeability formation step-by-step well killing scheme of the application.

[0098] Figure 9 It is a high-pressure and high-permeability formation well killing scheme of the application.

[0099] Figure 10 It is a double-layer pipe reverse circulation drilling well closing control method of the application.

[0100] REFERENCE NUMERALS:

[0101] 1. No. 1 flat valve, 2. drilling fluid return pressure gauge, 3. drilling fluid return flowmeter, 4. drilling fluid return throttle valve, 5. drilling fluid solid control device, 6. No. 2 flat valve, 7. top drive adapter, 8. No. 3 flat valve, 9. No. 4 flat valve, 10. drilling fluid pump-in pressure gauge, 11. drilling fluid pump-in flowmeter, 12. drilling pump, 13. mud pit, 14. double-layer pipe, 15. surface blowout preventer set, 16. casing, 17. liquid supplement system pressure gauge, 18. No. 5 flat valve, 19. No. 1 check valve, 20. No. 1 flowmeter of liquid supplement system, 21. liquid supplement pump, 22. No. 2 flowmeter of liquid supplement system, 23. No. 2 check valve, 24. throttle valve of liquid supplement system, 25. liquid supplement tank, 26. control terminal, 27. drill pipe plug valve, 28. annular check valve, 29. check valve, 30. downhole lifting and cleanup mechanism. DETAILED DESCRIPTION

[0102] The concept, specific structure and generated technical effects of the present application will be described clearly and completely in combination with the embodiments and the drawings, so as to fully understand the purpose, features and effects of the present application.

[0103] Embodiment 1

[0104] A well bottom lifting and cleanup reverse circulation drilling well control system, as shown in the figure, comprises: Figure 1 A circulating mud control system I for controlling drilling fluid pump-in and return;

[0105] A large annular liquid supplement system II for balancing well bottom pressure and conducting kill operation;

[0106] A control terminal 26 connected with the circulating mud control system and the large annular liquid supplement system, the control terminal 26 controls the circulating mud control system and the large annular liquid supplement system to operate, and conducts normal circulation drilling working condition, reverse circulation drilling working condition, overflow treatment working condition, shut-in treatment working condition and well leakage treatment working condition.

[0107] As shown in the figure, the circulating mud control system comprises, in sequence through pipeline connection, a drill pipe plug valve 27, a No. 1 flat valve 1, a drilling fluid return pressure gauge 2, a drilling fluid return flowmeter 3, a drilling fluid return throttle valve 4, a drilling fluid solid control device 5, a mud pit 13, a drilling pump 12, a drilling fluid pump-in flowmeter 11, a drilling fluid pump-in pressure gauge 10, and a No. 4 flat valve 9, the pipelines connected with the drill pipe plug valve 27 and the No. 4 flat valve 9 are both communicated to the top drive adapter 7 at the top end of the double-layer pipe 14.

[0108] Figure 1 As shown in the figure, the large annular liquid supplement system II comprises, in sequence through pipeline connection, a No. 5 flat valve 18, a No. 1 check valve 19, a No. 1 flowmeter 20 of liquid supplement system, a liquid supplement pump 21, a No. 2 flowmeter 22 of liquid supplement system, a No. 2 check valve 23, a throttle valve 24 of liquid supplement system, a liquid supplement tank 25, a liquid supplement system pressure gauge 17, and a casing 16, the pipeline connected with the No. 5 flat valve 18 is communicated to the top drive adapter 7 at the top end of the double-layer pipe 14.

[0109] As shown in the figure, the control terminal 26 is connected with the circulating mud control system and the large annular liquid supplement system, and controls the circulating mud control system and the large annular liquid supplement system to operate, and conducts normal circulation drilling working condition, reverse circulation drilling working condition, overflow treatment working condition, shut-in treatment working condition and well leakage treatment working condition. Figure 1 ​As shown, the pipe behind the drill pipe cock valve 27 is connected with the pipe behind the drilling fluid pump-in pressure gauge 10, and a first pipe is arranged between the two pipes, and a second flat valve 6 is arranged on the first pipe; a third flat valve 8 is arranged on the pipe behind the first flat valve 1 and the pipe behind the fourth flat valve 9.

[0110] As shown in the figure, Figure 1 As shown, the lower part of the double-layer pipe 14 is inserted into the casing 16, and a downhole lifting and assisting mechanism 30, a one-way check valve 29 and a ring-shaped one-way valve 28 connected with the casing 16 are arranged in the double-layer pipe 14, and a surface blowout preventer group 15 is arranged at the top end of the casing 16.

[0111] As shown in the figure, Figure 1 As shown, the large annular space liquid supplementing system includes a liquid supplementing system pressure gauge 17, a fifth flat valve 18, a first one-way valve 19, a liquid supplementing system first flowmeter 20, a liquid supplementing pump 21, a liquid supplementing tank 25, a liquid supplementing system throttle valve 24, a second one-way valve 23 and a liquid supplementing system second flowmeter 22 which are sequentially connected by pipes, the pipe connected with the liquid supplementing system pressure gauge 17 is connected to the casing 16, and the pipe connected with the liquid supplementing system second flowmeter 22 is connected to the pipe between the fifth flat valve 18 and the first one-way valve 19.

[0112] The control terminal 26 acquires the data of the drilling fluid pump-in flowmeter 11, the drilling fluid pump-in pressure gauge 10, the drilling fluid return flowmeter 3, the drilling fluid return pressure gauge 2, the liquid supplementing system pressure gauge 17, the liquid supplementing system first flowmeter 20 and the liquid supplementing system second flowmeter 22 in real time.

[0113] The control terminal 26 compares and analyzes the drilling fluid pump-in flow and return flow to determine the downhole working condition.

[0114] When the drilling fluid pump-in flow is equal to the drilling fluid pump-out flow, it is a normal drilling working condition;

[0115] When the drilling fluid pump-in flow is less than the drilling fluid pump-out flow, overflow condition occurs in the downhole, and bottom hole pressure reduction control or well killing and well closing measures need to be taken;

[0116] When the drilling fluid pump-in flow is greater than the drilling fluid pump-out flow, well leakage condition occurs in the downhole, and bottom hole pressure increase control needs to be performed.

[0117] The control terminal 26 controls the opening degree of the drilling fluid return throttle valve 4 and the liquid supplementing system throttle valve 24, and controls the opening and closing of the drilling pump 12, the liquid supplementing pump 21, the first flat valve 1, the second flat valve 6, the third flat valve 8, the fourth flat valve 9 and the fifth flat valve 18 according to the downhole working condition.

[0118] Example 2

[0119] The embodiment is further illustrated on the basis of the example 1, and the positive circulation drilling condition comprises the following steps as shown in Figure 1 and 2 .

[0120] Step S11, closing the second flat valve 6 and the third flat valve 8;

[0121] Step S12, opening the first flat valve 1 and the fourth flat valve 9;

[0122] Step S13, opening the drilling pump 12;

[0123] Step S14, starting the positive circulation drilling.

[0124] Example 3

[0125] The embodiment is further illustrated on the basis of the example 2, and the reverse circulation drilling condition comprises the following steps as shown in Figure 1 and 2 .

[0126] Step S21, closing the first flat valve 1 and the fourth flat valve 9;

[0127] Step S22, opening the second flat valve 6 and the third flat valve 8;

[0128] Step S23, opening the drilling pump 12;

[0129] Step S24, starting the reverse circulation drilling.

[0130] Example 4

[0131] The embodiment is further illustrated on the basis of the example 3, and the overflow treatment condition comprises: when the overflow amount is small, adjusting by increasing the bottom hole pressure; and when the overflow amount is large, adjusting by killing the well. Figure 1 and 3 .

[0132] 1. Small overflow amount

[0133] When the overflow amount is small, adjusting by increasing the bottom hole pressure, as shown in Figure 3 , comprises the following steps:

[0134] Step S31, reducing the opening of the drilling fluid return throttle valve 4;

[0135] Step S32, closing the first flat valve 1 and the fourth flat valve 9;

[0136] Step S33, opening the second flat valve 6 and the third flat valve 8;

[0137] Step S34, open the drilling pump 12;

[0138] Step S35, inject high-density drilling fluid into the annulus of the drilling tool outer tube;

[0139] Step S36, when the overflow is 0, stop the action, and realize well control.

[0140] When the annular drilling fluid still cannot balance the formation pressure, it further includes:

[0141] Step S38, open the No. 5 flat valve 18;

[0142] Step S39, open the liquid supplement pump 21;

[0143] Step S40, inject high-density mud into the wellbore annulus, increase the annular heavy mud column height, and further increase the bottom hole pressure.

[0144] According to the "China Petroleum and Natural Gas Group Company Oil and Natural Gas Downhole Operation Well Control Standard" drawing Figure 4 、 Figure 5 , combined with Figure 1 、 Figure 4 、 Figure 5 , Figure 4 、 Figure 5 , A is the double-wall drill pipe inner tube light mud return valve, which is equivalent to the drilling fluid return valve 4 in Figure 1 , the downhole lifting and assisting mechanism is equivalent to the downhole lifting and assisting mechanism 30 in Figure 1 . P1 injects light mud, reduces the opening degree of A valve, which is equivalent to the process of step S31-step S37. P2 injects heavy mud, which is equivalent to the process of step S38-S40 in Figure 1 .

[0145] 2, when the overflow is large

[0146] When the overflow is large, the adjustment is carried out by killing well, including: low-pressure low-permeability formation one-time killing method, low-pressure low-permeability formation step-by-step killing method, and high-pressure high-permeability formation killing method adjustment.

[0147] (1) Low-pressure low-permeability formation one-time killing

[0148] As shown in Figure 3 , the low-pressure low-permeability formation one-time killing method includes the following steps:

[0149] Step S41, close the No. 2 flat valve 6 and the No. 4 flat valve 9;

[0150] Step S42, open the No. 1 flat valve 1, open the No. 3 flat valve 8, and open the drilling pump 12;

[0151] Step S43, open the No. 5 flat valve 18;

[0152] Step S44, simultaneously inject the well killing fluid into the inner tube water hole and the drilling tool annulus, and top the annulus heavy slurry to the manifold blowout;

[0153] Step S45, when the overflow volume is 0, stop the operation, and realize the well control.

[0154] According to the “China Petroleum and Natural Gas Group Company Oil and Natural Gas Downhole Operation Well Control Standard Regulations”, draw Figure 6 , combined with Figure 1 , Figure 6 , the well killing fluid is simultaneously injected into the bottom of the well from the drilling tool annulus P1 and the inner tube water hole P3 of the double-wall drill pipe, and the heavy slurry return outlet valve C is opened to top the annulus heavy slurry and discharge from the choke manifold, which is equivalent to the processes of steps S41-S45.

[0155] (2) Step-by-step well killing in low-pressure and low-permeability formation

[0156] As shown in Figure 3 , the step-by-step well killing method in low-pressure and low-permeability formation includes the following steps:

[0157] First step, first press the wellbore annulus:

[0158] Step S51, open the No. 5 flat valve 18;

[0159] Step S52, close the No. 1 flat valve 1 and the No. 4 flat valve 9;

[0160] Step S53, open the No. 2 flat valve 6 and the No. 3 flat valve 8;

[0161] Step S54, open the drilling pump 12;

[0162] Step S55, when the casing pressure drops to 0, close the No. 5 flat valve 18, and thus the wellbore annulus part of the well killing is completed;

[0163] Second step, press the inner tube water hole:

[0164] Step S61, close the No. 2 flat valve 6 and the No. 3 flat valve 8;

[0165] Step S62, open the No. 1 flat valve 1 and the No. 4 flat valve 9;

[0166] Step S63, close the No. 5 flat valve 18;

[0167] Step S64, open the drilling pump 12;

[0168] Step S65, until the inner tube water hole shut-in pressure drops to 0, and thus the whole well killing process is completed.

[0169] According to the "China Petroleum and Natural Gas Group Company Oil and Gas Downhole Operation Well Control Standard Regulations" draw Figure 7 、 Figure 8 , combined with Figure 1 、 Figure 7 、 Figure 8 , Figure 7 、 Figure 8 C, equivalent to Figure 1 5th plate valve 18, P3 return valve (inner tube water eye) valve B, equivalent to Figure 1 1st plate valve 1.

[0170] Step 1: Close the P3 return valve, open valve C. The well killing fluid is injected from the P1 light slurry injection port, through the double-wall drilling tool annulus to the bottom of the well, and the annulus drilling fluid is discharged through the choke manifold. When the casing pressure drops to 0, close valve C, equivalent to steps S51-S55, thus completing the wellbore annulus part of the well killing.

[0171] Step 2: Close valve C, open valve B at P3 return (inner tube water eye), well killing fluid is injected from P1 light slurry injection port, through double-wall drilling tool annulus to the bottom of the well, and the inner tube mud is discharged through the choke manifold until the inner tube water eye shut-in pressure drops to 0, equivalent to steps S61-S65, thus completing the entire well killing process.

[0172] (3) High pressure and high permeability formation well killing

[0173] As shown in Figure 3 , the high pressure and high permeability formation well killing method comprises the following steps:

[0174] Step S71, close the second plate valve 6, close the fourth plate valve 9;

[0175] Step S72, open the first plate valve 1, open the third plate valve 8, and open the drilling pump 12;

[0176] Step S73, open the fifth plate valve 18;

[0177] Step S74, open the liquid supplementing pump 21;

[0178] Step S75, three channels simultaneously inject well killing fluid, and all mud is injected into the formation.

[0179] According to the "China Petroleum and Natural Gas Group Company Oil and Gas Downhole Operation Well Control Standard Regulations" draw Figure 9 , combined with Figure 1 , Figure 9 , inject well killing fluid through P2 heavy slurry injection port and P3 heavy slurry return port, equivalent to steps S71-S75.

[0180] Example 5

[0181] This embodiment, based on embodiment 4, further elaborates on the well shut-in treatment conditions, such as... Figure 1 and 3 As shown, the well shut-in process includes the following steps:

[0182] Step S81: Manually close the drill pipe plug valve 27 to close the drill string inner tubing wellbore;

[0183] Step S82: The mud-driven bottom hole annular check valve 28 and check valve 29 are closed, thus closing the annulus of the drill string outer casing;

[0184] Step S83: Close the No. 5 flat valve 18;

[0185] Step S84: Shut down the ground blowout preventer assembly 15.

[0186] Draw according to the "Standards for Well Control of Oil and Gas Downhole Operations of China National Petroleum Corporation" Figure 10 , combined Figure 1 , Figure 10 , Figure 10 Zhong 2# is the control valve for the annular heavy slurry injection port of the wellbore, equivalent to Figure 1 The No. 5 flat valve 18 and No. 17 are square drill pipe stopcocks, equivalent to... Figure 1 Chinese drill pipe plug 27, surface blowout preventer assembly, equivalent to Figure 1 The ground-based blowout preventer assembly #15 and #18 are annular check valves, equivalent to Figure 1 The annular check valves #28 and #19 are one-way check valves, equivalent to... Figure 1 28. One-way check valve.

[0187] Close the heavy slurry injection port control valve #2, and simultaneously close the surface blowout preventer assembly, close the square drill pipe valve and the top drive internal blowout preventer #17, seal the drill pipe injection channel, close the annular check valve #18, seal the drill pipe inner tube return channel, close the one-way check valve #19, and seal the drill pipe outer tube return channel to achieve well shut-in, which is equivalent to steps S81-S84.

[0188] Example 6

[0189] This embodiment, based on Embodiment 5, further elaborates on the well leakage treatment conditions, such as... Figure 1 and 2 As shown, the well leakage treatment process includes the following steps:

[0190] When the leakage is small, the adjustment can be made by reducing the bottom hole pressure:

[0191] Step S91: Close plate valve 1 (number 1) and plate valve 9 (number 4);

[0192] Step S92, open the second flat valve 6 and the third flat valve 8;

[0193] Step S93, open the drilling pump 12;

[0194] Step S94, increase the displacement, and drive the downhole lifting and cleanup mechanism 30 to work by the mud;

[0195] Step S95, when the loss is 0, stop the action, and realize the well control.

[0196] In combination Figure 1 , Figure 4 , keep the A valve opening, increase the P1 injection flow, increase the input power, drive the downhole cleanup mechanism to work, lower the annular fluid level, and reduce the bottom hole pressure, which is equivalent to the process of steps S91-S95.

[0197] The embodiments of the present application are specifically described above, but the present application is not limited to the described embodiments, and those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A bottom-hole lift-assisted reverse circulation drilling well control system, characterized in that, include: A circulating mud control system for controlling the pumping in and out of drilling fluid; A large annular fluid replenishment system used to balance bottom hole pressure and perform well control operations; The control terminal is connected to the circulating mud control system and the large annulus fluid replenishment system. The control terminal controls the operation of the circulating mud control system and the large annulus fluid replenishment system to perform forward circulation drilling, reverse circulation drilling, overflow treatment, shut-in treatment, and well leakage treatment. The circulating mud control system includes, in sequence, a drill pipe plug valve, a No. 1 flat plate valve, a drilling fluid return pressure gauge, a drilling fluid return flow meter, a drilling fluid return throttle valve, a drilling fluid solids control device, a mud pit, a drilling pump, a drilling fluid pump inlet flow meter, a drilling fluid pump inlet pressure gauge, and a No. 4 flat plate valve. The pipelines connected to the drill pipe plug valve and the No. 4 flat plate valve are both connected to the top drive adapter at the top of the double-layer pipe. A first pipeline is provided between the pipeline at the rear end of the drill pipe plug valve and the pipeline at the rear end of the drilling fluid pump in pressure gauge, and a second flat valve is provided on the first pipeline; a second pipeline is provided between the pipeline at the rear end of the first flat valve and the pipeline at the rear end of the fourth flat valve, and a third flat valve is provided on the second pipeline. The lower part of the double-layer pipe is inserted into the casing. The double-layer pipe is equipped with a downhole lifting and drainage mechanism, a one-way check valve, and an annular one-way valve that connects to the casing. The top of the casing is equipped with a surface blowout preventer assembly. The large annular fluid replenishment system includes a fluid replenishment system pressure gauge, a No. 5 flat valve, a No. 1 check valve, a No. 1 fluid replenishment system flow meter, a fluid replenishment pump, a fluid replenishment tank, a fluid replenishment system throttle valve, a No. 2 check valve, and a No. 2 fluid replenishment system flow meter, all connected in sequence via pipelines. The pipeline connected to the fluid replenishment system pressure gauge is connected to the casing, and the pipeline connected to the No. 2 fluid replenishment system flow meter is connected to the pipeline between the No. 5 flat valve and the No. 1 check valve.

2. The drilling control system as described in claim 1, characterized in that, The control terminal acquires data in real time from the drilling fluid pump inlet flow meter, drilling fluid pump inlet pressure gauge, drilling fluid return flow meter, drilling fluid return pressure gauge, replenishment system pressure gauge, replenishment system flow meter 1, and replenishment system flow meter 2.

3. The drilling control system as described in claim 1, characterized in that, The control terminal determines the downhole operating conditions by comparing and analyzing the inflow and outflow of drilling fluid. When the flow rate of drilling fluid pumped in equals the flow rate of drilling fluid pumped out, it is considered a normal drilling condition. When the flow rate of the drilling fluid pumped in is less than the flow rate of the drilling fluid pumped out, an overflow condition occurs downhole, requiring bottomhole pressure reduction or well control / shutdown measures. When the flow rate of the drilling fluid pumped in exceeds the flow rate of the drilling fluid pumped out, well leakage occurs downhole, requiring bottomhole pressure boosting.

4. The drilling control system as described in claim 1, characterized in that, The control terminal controls the opening degree of the drilling fluid return throttle valve and the replenishment system throttle valve according to the downhole working conditions, and controls the opening and closing of the drilling pump, replenishment pump, No. 1 plate valve, No. 2 plate valve, No. 3 plate valve, No. 4 plate valve, and No. 5 plate valve.

5. The drilling control system as described in claim 1, characterized in that, The positive circulation drilling operation includes the following steps: Step S11: Close plate valve No. 2 and plate valve No. 3; Step S12: Open plate valve No. 1 and plate valve No. 4; Step S13: Turn on the drilling pump; Step S14: Start positive circulation drilling.

6. The drilling control system as described in claim 1, characterized in that, The reverse circulation drilling operation includes the following steps: Step S21: Close plate valve No. 1 and plate valve No. 4; Step S22: Open plate valve No. 2 and plate valve No. 3; Step S23: Turn on the drilling pump; Step S24: Start reverse circulation drilling.

7. The drilling control system as described in claim 1, characterized in that, The overflow handling conditions include: when the overflow volume is small, adjusting by increasing the bottom hole pressure; when the overflow volume is large, adjusting by well control.

8. The drilling control system as described in claim 7, characterized in that, When the overflow rate is small, it is regulated by increasing the bottom hole pressure, including the following steps: Step S31: Reduce the opening of the drilling fluid return throttle valve; Step S32: Close plate valve No. 1 and plate valve No. 4; Step S33: Open plate valve No. 2 and plate valve No. 3; Step S34: Turn on the drilling pump; Step S35: Inject high-density drilling fluid into the annulus of the drill string; Step S36: When the overflow rate is 0, stop the operation to achieve well control.

9. The drilling control system as described in claim 8, characterized in that, When the annular drilling fluid still cannot balance the formation pressure, it also includes: Step S38: Open the No. 5 flat valve; Step S39: Turn on the infusion pump; Step S40: Inject high-density mud into the wellbore annulus to increase the height of the heavy mud column in the annulus and further increase the bottom hole pressure.

10. The drilling control system as described in claim 7, characterized in that, When the overflow is large, it can be regulated by well control, including: single well control method for low-pressure and low-permeability formations, step-by-step well control method for low-pressure and low-permeability formations, and well control method for high-pressure and high-permeability formations.

11. The drilling control system as described in claim 10, characterized in that, The method for controlling wells in low-pressure, low-permeability formations in a single operation includes the following steps: Step S41: Close the No. 2 flat plate valve and close the No. 4 flat plate valve; Step S42: Open the No. 1 flat plate valve, open the No. 3 flat plate valve, and turn on the intermediate drilling pump; Step S43: Open the No. 5 flat valve; Step S44: Simultaneously inject kill fluid into the annulus of the inner tube water hole and the outer tube of the drill string, and then inject heavy slurry into the choke manifold for release. Step S45: When the overflow rate is 0, stop the operation to achieve well control.

12. The drilling control system as described in claim 10, characterized in that, The step-by-step well control method for low-pressure, low-permeability formations Includes the following steps: The first step is to fill the annulus in the wellbore: Step S51: Open the No. 5 flat valve; Step S52: Close plate valve No. 1 and plate valve No. 4; Step S53: Open plate valve No. 2 and plate valve No. 3; Step S54: Turn on the drilling pump; Step S55: When the casing pressure drop is 0, close the No. 5 flat valve. This completes the well kill operation in the annulus of the wellbore. The second step is to press the water inlet of the inner pipe: Step S61: Close plate valve No. 2 and plate valve No. 3; Step S62: Open plate valve No. 1 and plate valve No. 4; Step S63: Close the No. 5 flat valve; Step S64: Turn on the drilling pump; Step S65: Continue until the shut-in pressure of the inner tube water hole drops to 0, thus completing the entire well control process.

13. The drilling control system as described in claim 10, characterized in that, The high-pressure, high-permeability formation pressure well control method includes the following steps: Step S71: Close the No. 2 flat plate valve and close the No. 4 flat plate valve; Step S72: Open the No. 1 flat valve, open the No. 3 flat valve, and turn on the drilling pump; Step S73: Open the No. 5 flat valve; Step S74: Turn on the infusion pump; Step S75: Simultaneously inject kill fluid into all three channels, and inject all the mud into the formation.

14. The drilling control system as described in claim 1, characterized in that, The well shut-in process includes the following steps: Step S81: Manually close the drill pipe stop valve and close the water inlet in the drill string; Step S82: The mud drives the bottom hole annular check valve and check valve to close, thus closing the annulus of the drill string's outer casing. Step S83: Close the No. 5 flat valve; Step S84: Shut down the ground blowout preventer assembly.

15. The drilling control system as described in claim 1, characterized in that, The well leakage handling process includes the following steps: When the leakage is small, the adjustment can be made by reducing the bottom hole pressure: Step S91: Close plate valve No. 1 and plate valve No. 4; Step S92: Open plate valve No. 2 and plate valve No. 3; Step S93: Turn on the drilling pump; Step S94: Increase the discharge rate, and the mud drives the downhole lifting and discharge mechanism to work; Step S95: When the leakage is 0, stop the operation to achieve well control.

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