Wellbore pressure experimental testing system and method in well killing process under complex working conditions

Abstract

The invention discloses a shaft pressure experiment testing system and method in the well killing process under complex working conditions. The shaft pressure experiment testing system comprises a target high-pressure stratum simulation device, a shaft, a drill string, a blowout preventer, a drilling fluid storage pool, a well killing fluid storage pool, a slurry preparing pool, a slurry pump, a high-pressure gas storage tank, a drilling tool lifting device, a first tee joint, a water hose, a data receiving terminal and a drill bit. The shaft is respectively communicated with the blowout preventer and the target high-pressure stratum simulation device; the left end of the first tee joint is communicated with the slurry pump through a pipeline, the right end of the first tee joint is communicated with the first electric valve through a pipeline, and the upper end of the first tee joint is communicated with the top end of the drill column through a water hose. The top end of the drill column is connected with the drilling tool lifting device; and the high-pressure gas storage tank is communicated with the target high-pressure stratum simulation device through a pipeline. According to the invention, multiple working conditions can be combined, well killing modes under different complex working conditions can be simulated, and the wellbore pressure in the well killing process can be predicted.

Description

Technical Field

[0001] The invention relates to a wellbore pressure experimental testing system and method in a well-killing process under complex working conditions, and belongs to the field of oil and gas drilling engineering. Background Art

[0002] During oil drilling, especially in deep drilling, due to the large size of the unconventional wellbore, the long drilling cycle, and the presence of multiple complex pressure systems in the formation, gas invasion, well kick, lost circulation and other complex conditions are prone to occur during the drilling process. Among them, the impact of gas invasion is the most serious. At the same time, it is also very important to shut down and kill the well after gas invasion. It is very important to analyze the pressure monitoring of the entire wellbore in order to formulate a corresponding well killing plan, so as to formulate a reasonable well killing plan to ensure the success of the well killing process and reduce the occurrence of secondary risks (including secondary gas invasion, lost circulation, etc.).

[0003] At present, there are three common methods for shutting in and killing the well after gas invasion in conventional wellbore, namely the conventional primary circulation method, secondary circulation method and pressure return method. However, for unconventional large-sized wellbore, due to the large wellbore size, large drilling fluid displacement and large circulation pressure consumption, when gas invasion and overflow occur, the well is shut down after the drill bit assembly is lifted. At this time, the pressure in the wellbore is still unclear, and the wellhead safety risk of killing the well is high. Summary of the invention

[0004] In order to overcome the defects in the prior art, the present invention aims to provide a wellbore pressure test system and method for a well killing process under complex working conditions.

[0005] The technical solution provided by the present invention to solve the above technical problems is: a wellbore pressure experimental test system for the well killing process under complex working conditions, including a target high-pressure formation simulation device, a wellbore, a drill string, a blowout preventer, a drilling fluid storage tank, a well killing fluid storage tank, a slurry preparation tank, a mud pump, a high-pressure gas storage tank, a drilling tool lifting device, a No. 1 tee, a water hose, a data receiving terminal and a drill bit;

[0006] The upper and lower ends of the wellbore are connected to the blowout preventer and the target high-pressure formation simulation device through flanges; both sides of the blowout preventer are respectively provided with a No. 1 electric valve and a No. 2 battery valve; the drill string is vertically installed in the blowout preventer, the bottom end of the drill string is connected to the drill bit and extends to the target high-pressure formation simulation device, and three centralizers are provided on the outer wall of the drill string located in the wellbore;

[0007] The left end of the No. 1 tee is connected to the mud pump through a pipeline, the right end is connected to the No. 1 electric valve through a pipeline, and the upper end is connected to the top of the drill string through a hose; a liquid flow meter and a No. 2 one-way valve are provided between the mud pump and the No. 1 tee;

[0008] The mud pump is connected to the drilling fluid storage tank and the well-killing fluid storage tank through pipelines, and the slurry preparation tank is also connected to the drilling fluid storage tank and the well-killing fluid storage tank through pipelines.

[0009] The top end of the drill string is connected to a drilling tool lifting device for lifting the drill string;

[0010] The high-pressure gas storage tank is connected to the target high-pressure formation simulation device through a pipeline, and a pressure reducing valve, an air flow meter, a No. 1 check valve, and a No. 1 pressure sensor are arranged between the target high-pressure formation simulation device and the high-pressure gas storage tank;

[0011] The wellbore is provided with a No. 2 pressure sensor, a No. 3 pressure sensor, and a No. 4 pressure sensor in sequence from bottom to top, and the No. 1 pressure sensor, No. 2 pressure sensor, No. 3 pressure sensor, No. 4 pressure sensor, and liquid flow meter are all electrically connected to the data receiving terminal.

[0012] A further technical solution is that the wellbore pressure test system also includes a waste liquid treatment tank, which is connected to the slurry distribution tank and the No. 2 battery valve through pipelines, and a waste liquid flow meter electrically connected to the data receiving terminal is provided between the No. 2 battery valve and the waste liquid treatment tank.

[0013] A further technical solution is that a density adjustment tank and a viscosity adjustment tank are provided on the slurry mixing tank.

[0014] A further technical solution is that the drill tool lifting device includes a No. 1 pulley block, a No. 2 pulley block, a No. 3 pulley block, and an electric winch; the wire rope of the electric winch passes through the No. 3 pulley block, the No. 2 pulley block, and the No. 1 pulley block in sequence and is connected to the top of the drill string, and the drill string is lifted by the electric winch.

[0015] A further technical solution is that the target high-pressure formation simulation device is a cylinder.

[0016] The wellbore pressure test method of the well killing process under complex working conditions specifically includes the following steps:

[0017] Step 1: Adjust the eccentricity of the drill string by adjusting the placement position of the centralizer;

[0018] Step 2: Drilling fluid of required density is prepared in the slurry preparation tank through the density adjustment tank and the viscosity adjustment tank, and the prepared drilling fluid is stored in the drilling fluid storage tank;

[0019] Step 3, start the mud pump, the drilling fluid passes through the liquid flow meter, No. 1 tee, and hose in sequence, enters the drill string from the top of the drill string, and then enters the target high-pressure formation simulation device through the drill bit. At this time, the inlet flow is the reading Q1 of the liquid flow meter;

[0020] Step 4, the drilling fluid entering the target high-pressure formation simulation device returns to the blowout preventer after entering the annulus between the drill string and the wellbore, and then passes through the No. 2 battery valve and the waste liquid flow meter to enter the waste liquid treatment tank in sequence. After being treated in the waste liquid treatment tank, it flows out from the bottom to the slurry preparation tank and the drilling fluid storage tank, and enters the cycle again. At this time, the outlet flow is the reading Q2 of the waste liquid flow meter;

[0021] Step 5, after a period of circulation, determine whether the inlet flow is equal to the outlet flow; if the inlet flow is equal to the outlet flow, the circulation is normal and proceed to the next step; if not, stop the circulation, find out the reason and restart the circulation until the inlet flow is equal to the outlet flow and proceed to the next step. At this time, the readings of pressure sensor No. 1, pressure sensor No. 2, pressure sensor No. 3 and pressure sensor No. 4 are P1, P2, P3 and P4 respectively;

[0022] Step 6: During the circulation process, open the high-pressure gas storage tank, and the high-pressure gas enters the target high-pressure formation simulation device through the pressure reducing valve, gas flow meter, and No. 1 pressure sensor. At this time, the pressure of the pressure reducing valve is P g , the reading of the gas flow meter is Q g1 , the reading of pressure sensor No. 1 is P'1;

[0023] Step 7, the gas entering the target high-pressure formation simulation device is returned from the annulus together with the drilling fluid, and then enters the waste liquid treatment tank through the No. 2 battery valve and the waste liquid flow meter. At this time, the readings of the No. 2 pressure sensor, the No. 3 pressure sensor, the No. 4 pressure sensor, and the waste liquid flow meter are P'2, P'3, P'4, and Q3 respectively;

[0024] Step 8: Turn off the mud pump and start the drilling tool lifting device at the same time, lift the drill string to above the target high-pressure formation simulation device, stop lifting, and then close the No. 2 electric valve to successfully shut in the well;

[0025] Step 9: Prepare a well-killing fluid of required density in the slurry preparation tank, and store the prepared well-killing fluid in a well-killing fluid storage tank;

[0026] Step 10, turn on the mud pump and adjust the well-killing fluid displacement to the target value. The well-killing fluid passes through the liquid flow meter, No. 1 tee, and hose in sequence, enters the drill string from the top of the drill string, and then passes through the drill bit into the target high-pressure formation simulation device. At this time, the reading of the liquid flow meter is Q m1 ;

[0027] Step 11: The well-killing fluid entering the target high-pressure formation simulation device returns to the blowout preventer after entering the annulus between the drill string and the wellbore, and then passes through the No. 2 battery valve and the waste liquid flow meter to enter the waste liquid treatment tank. After being treated in the waste liquid treatment tank, it flows out from the bottom to the slurry preparation tank and the well-killing fluid storage tank, and enters the cycle again. At this time, the reading of the waste liquid flow meter is Qm2 ; The readings of pressure sensor No. 1, pressure sensor No. 2, pressure sensor No. 3, and pressure sensor No. 4 are P"1, P"2, P"3, and P"4 respectively;

[0028] Step 12: Continue to inject gas and inject the killing fluid for circulation until there is no gas in the wellbore. The No. 1 pressure sensor, the No. 2 pressure sensor, the No. 3 pressure sensor, and the No. 4 pressure sensor measure the final circulation pressure P. e 1. P e 2. P e 3. P e 4;

[0029] Step 13: Close the high-pressure gas storage tank, stop the pump, and the well pressure is completed.

[0030] A further technical solution is that the eccentricity of the drill string in step 1 is determined by the following formula:

[0031]

[0032] Where: ε is the eccentricity of the drill string; Δx is the distance between the two centers of the wellbore and the drill pipe along the wellbore centerline section, m; d in1 is the inner diameter of the wellbore, m; d out2 is the outer diameter of the drill string, m.

[0033] A further technical solution is that the density of the well killing fluid is greater than the density of the drilling fluid;

[0034]

[0035] Where: p 5,w is the measured stable standpipe pressure, MPa; ρ1 is the density of the well-killing fluid, kg / m 3 ; ρ0 is the density of drilling fluid, kg / m 3 .

[0036] The present invention has the following beneficial effects: the present invention can simulate well-killing methods under different complex working conditions by combining a variety of working conditions, and predict the wellbore pressure during the well-killing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the system of the present invention.

[0038] As shown in the figure: 1-density regulating tank, 2-viscosity regulating tank, 3-slurry mixing tank, 4-drilling fluid storage tank, 5-well killing fluid storage tank, 6-mud pump, 7-high-pressure gas storage tank, 8-target high-pressure formation simulation device, 9-electric winch, 10-blowout preventer, 11-wellbore, 12-centralizer, 13-drill string, 14-drill bit, 15-No. 1 pulley block, 16-waste liquid treatment tank, 17-No. 1 tee, 18-liquid flow meter, 19-check valve No. 2, 20-gas flow meter, 21-pressure sensor No. 1, 22-electric valve No. 1, 23-pressure reducing valve, 24-electric valve No. 2, 25-water hose, 26-, 27-gas pipeline, 28-wire rope, 29-data receiving terminal, 30-pulley block No. 2, 31-annulus, 32-pulley block No. 3, 33-pressure sensor No. 2, 34-pressure sensor No. 3, 35-pressure sensor No. 4. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] like Figure 1 As shown, the wellbore pressure experimental test system of the well killing process under complex working conditions of the present invention comprises a target high-pressure formation simulation device 8, a wellbore 11, a drill string 13, a blowout preventer 10, a drilling fluid storage tank 4, a well killing fluid storage tank 5, a slurry preparation tank 3, a mud pump 6, a high-pressure gas storage tank 7, a drilling tool lifting device, a No. 1 tee 17, a water hose 25, a data receiving terminal 29, a waste liquid treatment tank 16 and a drill bit 14 installed at the lower end of the drill string 13;

[0041] The upper and lower ends of the wellbore 11 are connected to the blowout preventer 10 and the target high-pressure formation simulation device 8 through flanges; both sides of the blowout preventer 10 are respectively provided with a No. 1 electric valve 22 and a No. 2 battery valve 24; the drill string 13 is vertically installed in the blowout preventer 10, and the bottom end of the drill string 13 extends into the target high-pressure formation simulation device 8. Three centralizers 12 are provided on the outer wall of the drill string 10 located in the wellbore 11;

[0042] The left end of the No. 1 tee 17 is connected to the mud pump 6 through a pipeline, the right end is connected to the No. 1 electric valve 22 through a pipeline, and the upper end is connected to the top of the drill string 13 through a hose 25; a liquid flow meter 18 and a No. 2 check valve 19 are provided between the mud pump 6 and the No. 1 tee 17;

[0043] The mud pump 6 is connected to the drilling fluid storage tank 4 and the well-killing fluid storage tank 5 through pipelines, and the slurry preparation tank 3 is also connected to the drilling fluid storage tank 4 and the well-killing fluid storage tank 5 through pipelines;

[0044] The top end of the drill string 13 is connected to a drilling tool lifting device for lifting the drill string 13;

[0045] The high-pressure gas storage tank 7 is connected to the target high-pressure formation simulation device 8 through a pipeline, and a pressure reducing valve 23, an air flow meter 20, a No. 1 check valve 26, and a No. 1 pressure sensor 21 are provided between the target high-pressure formation simulation device 8 and the high-pressure gas storage tank 7;

[0046] The wellbore 11 is provided with a second pressure sensor 33, a third pressure sensor 34, and a fourth pressure sensor 35 from bottom to top, and the first pressure sensor 21, the second pressure sensor 33, the third pressure sensor 34, the fourth pressure sensor 35, and the liquid flow meter 18 are all electrically connected to the data receiving terminal;

[0047] The waste liquid treatment tank 16 is connected to the slurry preparation tank 3 and the No. 2 battery valve 24 through pipelines, and a waste liquid flow meter 27 electrically connected to the data receiving terminal is provided between the No. 2 battery valve 24 and the waste liquid treatment tank 16.

[0048] like Figure 1 As shown, in order to facilitate on-site preparation of well-killing fluid and drilling fluid in this embodiment, a preferred implementation is that a density adjustment tank 1 and a viscosity adjustment tank 2 are provided on the slurry preparation tank 3.

[0049] like Figure 1 As shown, in this embodiment, a preferred mode of the drilling tool lifting device is to include a No. 1 pulley block 15, a No. 2 pulley block 30, a No. 3 pulley block 32, and an electric winch 9; the wire rope 28 of the electric winch 9 passes through the No. 3 pulley block 32, the No. 2 pulley block 30, and the No. 1 pulley block 15 in sequence and is connected to the top of the drill string 13, and the drill string 13 is driven by the electric winch 9 to be lifted.

[0050] In this embodiment, the target high-pressure formation simulation device 8 is a cylinder.

[0051] A method for testing the wellbore pressure during the well killing process under complex working conditions is provided. The method adopts the wellbore pressure testing system for the well killing process under complex working conditions to perform the test, and specifically comprises the following steps:

[0052] Step 1, adjusting the eccentricity of the drill string 13 by adjusting the placement position of the centralizer 12;

[0053] The eccentricity of the drill string 13 is determined by the following formula:

[0054]

[0055] Where: ε is the eccentricity of the drill string; Δx is the distance between the two centers of the wellbore and the drill pipe along the wellbore centerline section, m; d in1 is the inner diameter of the wellbore, m; d out2 is the outer diameter of the drill string, m;

[0056] Step 2: Drilling fluid of required density is prepared in the slurry preparation tank 3 through the density adjustment tank 1 and the viscosity adjustment tank 2, and the prepared drilling fluid enters the drilling fluid storage tank 4 for storage;

[0057] Step 3, start the mud pump 6, the drilling fluid passes through the liquid flow meter 18, the No. 1 tee 17, the hose 25 in sequence, enters the drill string 13 from the top of the drill string 13, and then passes through the drill bit 14 into the target high-pressure formation simulation device 8. At this time, the inlet flow is the reading Q1 of the liquid flow meter 18;

[0058] Step 4, the drilling fluid entering the target high-pressure formation simulation device 8 returns to the blowout preventer 10 after entering the annulus 31 between the drill string 13 and the wellbore 11, and then passes through the No. 2 battery valve 24 and the waste liquid flow meter 27 to enter the waste liquid treatment tank 16, and after being treated in the waste liquid treatment tank 16, it flows out from the bottom to the slurry preparation tank 3 and the drilling fluid storage tank 4, and enters the cycle again. At this time, the outlet flow is the reading Q2 of the waste liquid flow meter 27;

[0059] Step 5, after a period of circulation, determine whether the inlet flow is equal to the outlet flow; if the inlet flow is equal to the outlet flow, the circulation is normal and the next step is continued; if not, the circulation is stopped, the cause is found and the circulation is restarted until the inlet flow is equal to the outlet flow and the next step is continued. At this time, the readings of the No. 1 pressure sensor 21, the No. 2 pressure sensor 33, the No. 3 pressure sensor 34 and the No. 4 pressure sensor 35 are P1, P2, P3 and P4 respectively;

[0060]

[0061] Where: P x is the pressure at a certain point in the wellbore, MPa; ρ0 is the density of the drilling fluid, kg / m 3 ;H x is the depth of a certain point in the wellbore, m; Q1 is the displacement of drilling fluid, L / s; f1 is the friction coefficient, dimensionless;

[0062] Step 6: During the circulation process, the high-pressure gas storage tank 7 is opened, and the high-pressure gas enters the target high-pressure formation simulation device 8 through the pressure reducing valve 23, the gas flow meter 20, and the No. 1 pressure sensor 21. At this time, the pressure P of the pressure reducing valve is g >P1, the reading of the gas flow meter is Q g1 , the reading of pressure sensor No. 1 is P'1;

[0063]

[0064] Where: Q g1 is the flow rate of injected gas, L / h; k is the adiabatic index, which is selected as 1.4 according to the nitrogen bottle used; p g is the pressure of injected gas, MPa; v is the velocity of injected gas, m / s.

[0065] Step 7, the gas entering the target high-pressure formation simulation device 8 is returned from the annulus 31 together with the drilling fluid, and then enters the waste liquid treatment tank 16 through the No. 2 battery valve 24 and the waste liquid flow meter 27. At this time, the readings of the No. 2 pressure sensor 33, the No. 3 pressure sensor 34, the No. 4 pressure sensor 35, and the waste liquid flow meter 27 are P'2, P'3, P'4, and Q3 respectively;

[0066] Among them, P'1<P1, P'2<P2, P'3<P3, P'4<P4,

[0067]

[0068] Q i =Q gi +Q gl

[0069] Where: P' x is the pressure at a certain point in the wellbore, MPa; ρ i is the density of the drilling fluid in the i-th section of the annulus, kg / m 3 ;H i is the depth of drilling fluid in the i-th section of the wellbore, m; Q i is the flow rate of the liquid column in the i-th section of the wellbore, L / s; f i is the friction coefficient, dimensionless;

[0070] Step 8, turn off the mud pump 6, and start the drilling tool lifting device at the same time, lift the drill string to above the target high-pressure formation simulation device 8, stop lifting, and then close the No. 2 electric valve 24, and the well is closed successfully;

[0071] Step 9, preparing a well-killing fluid of required density in the slurry preparation tank 3, and storing the prepared well-killing fluid in the well-killing fluid storage tank 5;

[0072] The density of the well killing fluid is greater than the density of the drilling fluid;

[0073]

[0074] Where: p 5,w is the measured stable standpipe pressure, MPa; ρ1 is the density of the well-killing fluid, kg / m 3 ; ρ0 is the density of drilling fluid, kg / m3 ;

[0075] Step 10, turn on the mud pump 6, adjust the well-killing fluid displacement to the target value, the well-killing fluid passes through the liquid flow meter 18, the No. 1 tee 17, the hose 25 into the drill string 13, and then passes through the drill bit 14 into the target high-pressure formation simulation device 8. At this time, the reading of the liquid flow meter 18 is Q m1 ;

[0076] Step 11, the well-killing fluid entering the target high-pressure formation simulation device 8 enters the annulus 31 and returns to the blowout preventer 10, and then passes through the No. 2 battery valve 24 and the waste liquid flow meter 27 to enter the waste liquid treatment tank 16, and after being treated in the waste liquid treatment tank 16, it flows out from the bottom to the slurry preparation tank 3 and the well-killing fluid storage tank 5, and enters the cycle again. At this time, the reading of the waste liquid flow meter 27 is Q m2 The readings of the pressure sensor No. 1 21, the pressure sensor No. 2 33, the pressure sensor No. 34, and the pressure sensor No. 4 35 are P"1, P"2, P"3, and P"4 respectively;

[0077]

[0078] Where: p bp is the wellhead back pressure, MPa, which can be changed by adjusting the No. 2 electric valve;

[0079] Step 12: Continue to inject gas and inject the killing fluid for circulation until there is no gas in the wellbore 11, and the No. 1 pressure sensor 21, the No. 2 pressure sensor 33, the No. 3 pressure sensor 34, and the No. 4 pressure sensor 35 measure the final circulation pressure P e 1. P e 2. P e 3. P e 4.

[0080]

[0081] Where: ρ1 is the density of the well-killing fluid, kg / m 3 ; Q4 is the displacement of the well-killing fluid, L / s; f1 is the friction coefficient, dimensionless;

[0082] Step 13, close the high-pressure gas storage tank 7, stop the pump, and the well pressure is completed.

[0083] The above description is not intended to limit the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are within the scope of the technical solution of the present invention.

Claims

1. Wellbore pressure test system for well killing process under complex working conditions, characterized by: It includes the target high-pressure formation simulation device, wellbore, drill string, blowout preventer, drilling fluid storage tank, well killing fluid storage tank, slurry preparation tank, mud pump, high-pressure gas storage tank, drilling tool lifting device, No. 1 tee, water hose, data receiving terminal and drill bit; The upper and lower ends of the wellbore are connected to the blowout preventer and the target high-pressure formation simulation device through flanges; both sides of the blowout preventer are respectively provided with a No. 1 electric valve and a No. 2 battery valve; the drill string is vertically installed in the blowout preventer, the bottom end of the drill string is connected to the drill bit and extends to the target high-pressure formation simulation device, and three centralizers are provided on the outer wall of the drill string located in the wellbore; The left end of the No. 1 tee is connected to the mud pump through a pipeline, the right end is connected to the No. 1 electric valve through a pipeline, and the upper end is connected to the top of the drill string through a hose; a liquid flow meter and a No. 2 one-way valve are provided between the mud pump and the No. 1 tee; The mud pump is connected to the drilling fluid storage tank and the well-killing fluid storage tank through pipelines, and the slurry distribution tank is also connected to the drilling fluid storage tank and the well-killing fluid storage tank through pipelines. The top end of the drill string is connected to a drilling tool lifting device for lifting the drill string; The high-pressure gas storage tank is connected to the target high-pressure formation simulation device through a pipeline, and a pressure reducing valve, an air flow meter, a No. 1 check valve, and a No. 1 pressure sensor are arranged between the target high-pressure formation simulation device and the high-pressure gas storage tank; The wellbore is provided with a No. 2 pressure sensor, a No. 3 pressure sensor, and a No. 4 pressure sensor in sequence from bottom to top, and the No. 1 pressure sensor, No. 2 pressure sensor, No. 3 pressure sensor, No. 4 pressure sensor, and liquid flow meter are all electrically connected to the data receiving terminal.

2. The wellbore pressure test system for well killing process under complex working conditions according to claim 1 is characterized in that: The wellbore pressure test system also includes a waste liquid treatment pool, which is connected to the slurry distribution pool and the No. 2 battery valve through pipelines. A waste liquid flow meter electrically connected to the data receiving terminal is provided between the No. 2 battery valve and the waste liquid treatment pool.

3. The wellbore pressure test system for well killing process under complex working conditions according to claim 2 is characterized in that: The slurry mixing pool is provided with a density regulating pool and a viscosity regulating pool.

4. The wellbore pressure test system for well killing process under complex working conditions according to claim 1 is characterized in that: The drilling tool lifting device includes a No. 1 pulley block, a No. 2 pulley block, a No. 3 pulley block, and an electric winch; the wire rope of the electric winch passes through the No. 3 pulley block, the No. 2 pulley block, and the No. 1 pulley block in sequence and is connected to the top of the drill string, and the drill string is lifted by the electric winch.

5. The wellbore pressure test system for well killing process under complex working conditions according to claim 1 is characterized in that: The target high-pressure formation simulation device is a cylinder.

6. A method for testing the wellbore pressure during well killing under complex working conditions, characterized in that: The method adopts the wellbore pressure experimental test system of the well killing process under complex working conditions as described in claim 3 or 4 to perform the test, and specifically comprises the following steps: Step 1: Adjust the eccentricity of the drill string by adjusting the placement of the centralizer; Step 2: Drilling fluid of required density is prepared in the slurry preparation tank through the density adjustment tank and the viscosity adjustment tank, and the prepared drilling fluid is stored in the drilling fluid storage tank; Step 3, start the mud pump, the drilling fluid passes through the liquid flow meter, No. 1 tee, and hose in sequence, enters the drill string from the top of the drill string, and then enters the target high-pressure formation simulation device through the drill bit. At this time, the inlet flow is the reading Q1 of the liquid flow meter; Step 4, the drilling fluid entering the target high-pressure formation simulation device returns to the blowout preventer after entering the annulus between the drill string and the wellbore, and then passes through the No. 2 battery valve and the waste liquid flow meter to enter the waste liquid treatment tank in sequence. After being treated in the waste liquid treatment tank, it flows out from the bottom to the slurry preparation tank and the drilling fluid storage tank, and enters the cycle again. At this time, the outlet flow is the reading Q2 of the waste liquid flow meter; Step 5, after a period of circulation, determine whether the inlet flow is equal to the outlet flow; if the inlet flow is equal to the outlet flow, the circulation is normal and proceed to the next step; if not, stop the circulation, find out the reason and restart the circulation until the inlet flow is equal to the outlet flow and proceed to the next step. At this time, the readings of pressure sensor No. 1, pressure sensor No. 2, pressure sensor No. 3 and pressure sensor No. 4 are P1, P2, P3 and P4 respectively; Step 6: During the circulation process, open the high-pressure gas storage tank, and the high-pressure gas enters the target high-pressure formation simulation device through the pressure reducing valve, gas flow meter, and No. 1 pressure sensor. At this time, the pressure of the pressure reducing valve is P g , the reading of the gas flow meter is Q g1 , the reading of pressure sensor No. 1 is P'1; Step 7, the gas entering the target high-pressure formation simulation device is returned from the annulus together with the drilling fluid, and then enters the waste liquid treatment tank through the No. 2 battery valve and the waste liquid flow meter. At this time, the readings of the No. 2 pressure sensor, the No. 3 pressure sensor, the No. 4 pressure sensor, and the waste liquid flow meter are P'2, P'3, P'4, and Q3 respectively; Step 8: Turn off the mud pump and start the drilling tool lifting device at the same time, lift the drill string to above the target high-pressure formation simulation device, stop lifting, and then close the No. 2 electric valve to successfully shut in the well; Step 9: Prepare a well-killing fluid of required density in the slurry preparation tank, and store the prepared well-killing fluid in a well-killing fluid storage tank; Step 10, turn on the mud pump and adjust the well-killing fluid displacement to the target value. The well-killing fluid passes through the liquid flow meter, No. 1 tee, and hose in sequence, enters the drill string from the top of the drill string, and then passes through the drill bit into the target high-pressure formation simulation device. At this time, the reading of the liquid flow meter is Q m1 ; Step 11: The well-killing fluid entering the target high-pressure formation simulation device returns to the blowout preventer after entering the annulus between the drill string and the wellbore, and then passes through the No. 2 battery valve and the waste liquid flow meter to enter the waste liquid treatment tank. After being treated in the waste liquid treatment tank, it flows out from the bottom to the slurry preparation tank and the well-killing fluid storage tank, and enters the cycle again. At this time, the reading of the waste liquid flow meter is Q m2 ; The readings of pressure sensor No. 1, pressure sensor No. 2, pressure sensor No. 3, and pressure sensor No. 4 are P"1, P"2, P"3, and P"4 respectively; Step 12: Continue to inject gas and inject the killing fluid for circulation until there is no gas in the wellbore. The No. 1 pressure sensor, the No. 2 pressure sensor, the No. 3 pressure sensor, and the No. 4 pressure sensor measure the final circulation pressure P. e 1. P e 2. P e 3. P e 4; Step 13: Close the high-pressure gas storage tank, stop the pump, and the well pressure is completed.

7. The method for testing wellbore pressure during well killing under complex working conditions according to claim 5 is characterized in that: The eccentricity of the drill string in step 1 is determined by the following formula: Where: ε is the eccentricity of the drill string; Δx is the distance between the two centers of the wellbore and the drill pipe along the wellbore centerline section, m; d in1 is the inner diameter of the wellbore, m; d out2 is the outer diameter of the drill string, m.

8. The method for testing wellbore pressure during well killing under complex working conditions according to claim 5 is characterized in that: The density of the well killing fluid is greater than the density of the drilling fluid; Where: p 5,w is the measured stable standpipe pressure, MPa; ρ1 is the density of the well-killing fluid, kg / m 3 ; ρ0 is the density of drilling fluid, kg / m 3 .

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