Device and method for testing gas cut resistance of formate buffer solution

Abstract

The invention provides a device and method for testing the gas invasion resistance of a formate buffer solution, and the device comprises a high-temperature and high-pressure dissolving tank for containing the formate buffer solution, the gas inlet of the high-temperature and high-pressure dissolving tank is communicated with the outlet of a gas injection system through a high-precision flow measurement control meter, and is used for controlling the flow of CO2 entering the high-temperature and high-pressure dissolving tank; an air outlet of the high-temperature and high-pressure dissolving tank is communicated with an inlet of the exhaust system, the pH measuring unit is in sealed connection with the high-temperature and high-pressure dissolving tank, and the measuring end of the pH measuring unit extends into the high-temperature and high-pressure dissolving tank and is used for detecting the pH value of a formate buffer solution at regular time; the display end of the pH measuring unit is connected with the data monitoring system and is used for acquiring the pH value of the formate buffer solution in real time. The device truly simulates the oil jacket annulus working condition under the CO2 gas invasion condition, effectively evaluates the gas invasion resistance of the formate buffer solution, and is simple in structure, convenient to operate and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development engineering, and in particular relates to a device and method for testing the gas invasion resistance of a formate buffer solution. Background Art

[0002] The inherent weak alkalinity of formate completion fluids makes them non-toxic, environmentally friendly, low-corrosive, high-temperature resistant, and reservoir-protective, making them highly effective in oil and gas field drilling and completion applications. However, CO2 intrusion can lower the pH of the formate system, accelerating formate decomposition and increasing corrosion rates. In severe cases, this can lead to fractures and failures in the oil and casing strings, resulting in significant economic losses. The addition of formate buffers can maintain a constant pH in the completion fluid and effectively inhibit formate decomposition. However, formate buffers are typically a mixture of carbonate and bicarbonate, and the ratio of these two salts directly influences the buffering effect. Therefore, it is necessary to test the gas intrusion resistance of formate buffer solutions using different buffer systems.

[0003] At present, the devices and methods for testing gas intrusion resistance are as follows:

[0004] Chinese patent CN 202975006 U discloses a device for testing the gas invasion resistance of well-killing fluid. The device aims to test the gas invasion resistance of well-killing fluid and select a well-killing fluid system with certain gas invasion resistance. The device consists of a high-pressure gas cylinder, a throttle valve, a digital pressure gauge, and a simulated tubing string. By comparing the gas invasion pressures at different test pressures and well-killing fluid components, the device characterizes the gas invasion resistance of the well-killing fluid. The device has the advantages of fast testing speed and strong practicality.

[0005] Chinese patent CN 104280313 B discloses a static testing method for the gas invasion resistance of oil and gas well working fluids. Using a multifunctional oil and gas well working fluid performance testing device consisting of an outer tube, a center tube, a simulated bottom hole, a temperature control device, and a circulating filter, the method measures the simulated oil and gas well characteristics and the temporal variation of the working fluid density under static well pressure conditions. The working fluid's gas invasion resistance is characterized by comparing the working fluid density before and after gas invasion. This method has the advantages of reducing working fluid maintenance costs and improving the working fluid's applicability.

[0006] Chinese patent CN 104297140 B discloses a method for dynamically testing the gas invasion resistance of oil and gas well working fluids. The method aims to provide a method for testing the gas invasion resistance of oil and gas well working fluids indoors, selecting working fluids with a certain gas invasion resistance that maintains a substantially unchanged density after gas invasion. This method uses a multifunctional oil and gas well working fluid performance testing device to measure the gas invasion resistance of oil and gas well working fluids under simulated oil and gas well characteristics and dynamic working fluid circulation conditions. This method has the advantages of low maintenance costs and strong practicality.

[0007] In summary, existing patents test the gas intrusion resistance of solutions mainly by comparing the pressure of gas intrusion and the density change of the solution. However, the above technology has problems such as being unable to simulate high temperature and high pressure environments, unable to accurately measure the amount of intrusive gas injection, and unable to detect in real time. Summary of the Invention

[0008] To address the challenges of the prior art, the present invention provides a device and method for testing the gas intrusion resistance of formate buffer solutions. The device comprises a gas injection system, a high-precision flow measurement and control instrument, a high-temperature, high-pressure dissolution tank, an exhaust system, a pH measurement unit, and a data monitoring system. By plotting a pH-to-CO2 inlet flow curve for the formate buffer system, the optimal buffer solution composition and dosage can be screened. This device realistically simulates the annular conditions of the casing under high temperature, high pressure, and CO2 gas intrusion, effectively evaluating the gas intrusion resistance of the formate buffer solution. It also features a simple structure, easy operation, and low cost.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a device for testing the gas intrusion resistance of a formate buffer solution, comprising a high-temperature and high-pressure dissolution tank for containing a formate buffer solution, the air inlet of the high-temperature and high-pressure dissolution tank being connected to the outlet of a gas injection system via a high-precision flow measurement controller for controlling the flow of CO2 entering the high-temperature and high-pressure dissolution tank, the air outlet of the high-temperature and high-pressure dissolution tank being connected to the inlet of an exhaust system, a pH measuring unit being sealedly connected to the high-temperature and high-pressure dissolution tank, a measuring end of the pH measuring unit extending into the high-temperature and high-pressure dissolution tank for periodically detecting the pH value of the formate buffer solution, and a display end of the pH measuring unit being connected to a data monitoring system for obtaining the pH value of the formate buffer solution in real time.

[0010] Furthermore, the high-temperature and high-pressure dissolution tank includes a solution tank body, a sealing cover, a temperature detector, a heater and a pressure detector. The sealing cover is sealed at the opening of the solution tank body. The sealing cover has multiple openings. The exhaust system, the high-precision flow measurement controller and the pH measurement unit are sealed and connected to the sealing cover through the openings. The temperature detector and the heater are arranged in the solution tank body, and the pressure detector is arranged on the sealing cover.

[0011] Furthermore, an inner liner is provided in the solution pool body, and a transparent hollow layer is provided between the inner liner and the solution pool body. The transparent hollow layer is used to fill with insulation material. The temperature detector and the heater are both arranged on the outer wall of the inner liner. The temperature detector, the heater and the controller are connected to realize the detection of the temperature of the formate buffer system and the control of the heater power.

[0012] Furthermore, a base is fixed at the lower end of the high-temperature and high-pressure dissolution tank, and the base is fixedly connected to the sealing cover.

[0013] Furthermore, a safety valve is provided on the sealing cover for regulating the pressure of the high-temperature and high-pressure dissolution tank.

[0014] Furthermore, the exhaust system is a high-pressure exhaust closed valve assembly; the pH measurement unit is a laboratory pH meter or a portable pH meter, and the data monitoring system is a digital camera.

[0015] Furthermore, the gas injection system includes a first gas injection device and a second gas injection device, the first gas injection device is an inert gas injection device, and the second gas injection device is a CO2 gas injection device.

[0016] The present invention also provides a method for testing the gas intrusion resistance of a formate buffer solution, which is carried out in the above-mentioned testing device, and the specific steps are as follows:

[0017] S1 introduces the formate buffer system into a high-temperature and high-pressure dissolution tank and uses a pH measurement unit to measure the initial pH value of the formate buffer system;

[0018] S2: Connect the first and second gas injection devices of the gas injection system to a high-precision flow measurement controller, set the flow rates of the first and second gas injections, first inject the first gas at a fixed flow rate into the high-temperature and high-pressure dissolution tank for deoxygenation, and then inject the second gas at a fixed flow rate into the high-temperature and high-pressure dissolution tank;

[0019] The S3 pH measurement unit regularly measures the pH value of the formate buffer system in the high-temperature and high-pressure dissolution tank;

[0020] The S4 data monitoring system obtains the pH value of the formate buffer system in the high-temperature and high-pressure dissolution tank, and uses the pH value of the formate buffer system and the set second gas injection flow rate to establish a formate buffer system pH value-second gas injection flow rate curve;

[0021] S5 obtains the CO2 limit gas intrusion volume under different buffer components and addition conditions based on the pH value-second gas injection flow rate curve of the formate buffer system.

[0022] Furthermore, in S2, the temperature of the high-temperature and high-pressure dissolution tank is between room temperature and 300°C, and the pressure is between normal pressure and 100 MPa.

[0023] Furthermore, in S2, the first gas injection and the second gas injection are injected into the high-temperature and high-pressure dissolution tank at a pressure of not less than 1.2 KPa.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The present invention discloses a device for testing the gas intrusion resistance of a formate buffer solution. The device has a simple structure and requires only setting the flow rate of the intruding gas on a high-precision flow measurement controller and turning on the switches of a pH measurement unit and a high-temperature and high-pressure dissolution tank controller. Simultaneously, the high-temperature and high-pressure dissolution tank of the present invention can realistically simulate high-difficulty well drilling construction conditions under high temperature, high pressure, and CO2 gas intrusion conditions, effectively evaluating the gas intrusion resistance of the formate buffer solution and thus realizing the gas intrusion resistance test of the formate buffer solution. The device has low investment, short time consumption, and convenient operation.

[0026] Furthermore, the high-temperature and high-pressure dissolution tank has a good heat preservation effect, and the temperature detector reading is intuitive, the heater has high heating efficiency, the controller is easy to operate, and it has a simple structure, easy operation and low cost.

[0027] Furthermore, the high-precision flow measurement controller can effectively and stably control the flow rate of the intruding gas with high accuracy, thereby achieving accurate measurement of the injection amount of the intruding gas.

[0028] Furthermore, the pH measurement unit can regularly measure the pH value of the formate system under continuous gas intrusion conditions with high accuracy.

[0029] Furthermore, the data monitoring system can monitor the pH measurement unit readings in real time, reduce labor costs, and store the monitoring data.

[0030] The testing device of the present invention has a simple structure and is easy to install and use. It can quickly complete the test of the gas intrusion resistance of the formate buffer system itself by changing the temperature, pressure, flow rate of the intruding gas and the components of the formate buffer, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The gas intrusion resistance testing device of the formate buffer solution of the present invention;

[0032] Figure 2 Different components of Na2CO3-NaHCO3 (the total amount of corrosion inhibitor is 17kg / m 3 ) conditions, where the horizontal axis is the CO2 flow rate (CO2 flow rate = CO2 flow rate × time); the vertical axis is the pH meter reading.

[0033] In the attached figure: 1—gas injection system, 2—high-precision flow measurement controller, 3—high-temperature and high-pressure dissolution tank, 4—exhaust system, 5—pH measurement unit, 6—data monitoring system, 7—solution tank body, 8—solution tank liner, 9—solution tank transparent hollow layer, 10—thermal insulation material, 11—first hole, 12—second hole, 13—sealing cover, 14—temperature detector, 15—heater, 16—controller, 17—base, 18—safety valve, 19—pressure detector. DETAILED DESCRIPTION

[0034] The following further details the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings and a specific embodiment, to provide those skilled in the art with a better understanding of the present invention. It should be understood that the specific embodiments described herein are only a portion of the entire embodiment and do not limit the scope of the present invention. Furthermore, to avoid confusion regarding the concepts disclosed herein, descriptions of known structures and technologies are omitted. The scope of protection provided by the present invention is limited to the disclosed measurement method and does not include protection for the components involved in the test device.

[0035] In order to make the expression clear and intuitive, the structural schematic diagram of the embodiment of the present invention has been enlarged and omitted in proportion and details. Therefore, the components, shapes, sizes and relative positions in the figure are all exemplary and deviate from the actual ones. Those skilled in the art can further design the above elements to meet actual needs.

[0036] The present invention provides a device for testing the gas intrusion resistance of a formate buffer solution, comprising a gas injection system 1, a high-precision flow measurement controller 2, a high-temperature and high-pressure dissolution tank 3, an exhaust system 4, which are sequentially connected through a pipeline; a pH measurement unit 5, and a data monitoring system 6, wherein:

[0037] The gas injection system 1 is used to provide a gas source for the gas invasion experiment. A gas supply device such as a high-pressure gas cylinder can be selected. Specifically, it includes a first gas injection device and a second gas injection device. The first gas injection device is an inert gas injection device, such as a high-purity N2 gas cylinder, and the second gas injection device is a CO2 gas injection device, such as a high-purity CO2 gas cylinder.

[0038] The high-precision flow measurement controller 2 is used to control the flow rate of the intruding gas so that the gas invades into the high-temperature and high-pressure dissolution tank 3.

[0039] The high-temperature and high-pressure dissolution tank 3 includes a solution tank body 7 and an inner liner 8. The inner liner 8 is arranged in the solution tank body 7 and is used to hold the formate buffer system. A transparent hollow layer 9 is provided between the inner liner 8 and the solution tank body 7. The transparent hollow layer 9 is filled with a heat-insulating material 10 to play a heat-insulating role. The solution tank body 7 is provided with a first hole 11 and a second hole 12 to facilitate filling of the heat-insulating material.

[0040] A sealing cover 13 is fixed to the upper opening of the high-temperature and high-pressure dissolution tank 3 through a threaded connection, and the exhaust system 4, the high-precision flow measurement controller 2 and the pH measurement unit 5 are respectively connected to the sealing cover 13 through threads and sealing rings; a base 17 is fixed to the lower end of the high-temperature and high-pressure dissolution tank 3 and is fixed to the sealing cover 13 through threads and sealing rings.

[0041] The exhaust system 4 can use components such as a high-pressure exhaust sealing valve to adjust the amount of gas output.

[0042] The pH measuring unit 5 can be a laboratory pH meter or a portable pH meter. The electrode of the pH meter is immersed in the formate buffer system and fixed to the sealing cover 13 by means of a thread and a sealing ring.

[0043] The data monitoring system 6 may use a digital camera such as a home network camera to monitor the reading of the pH measurement unit 5 .

[0044] Preferably, the high-temperature and high-pressure dissolution tank 3 is also equipped with a temperature detector 14, a heater 15 and a controller 16. The temperature detector 14 is located on the side of the outer wall of the inner tank of the high-temperature and high-pressure dissolution tank and is used to detect the temperature of the formate buffer system; the heater 15 is located at the bottom of the outer wall of the inner tank of the high-temperature and high-pressure dissolution tank and is used to heat the formate buffer system; the controller 16 is connected to the heater 15 to control the heater 15 to heat.

[0045] Preferably, the high-temperature and high-pressure dissolution tank 3 is equipped with a pressure detector 19, which can detect the pressure inside the high-temperature and high-pressure dissolution tank 3 in real time.

[0046] Preferably, the temperature of the high-temperature and high-pressure dissolution tank 3 is about room temperature to 300° C., and the pressure is about normal pressure to 100 MPa.

[0047] Preferably, the sealing cover 13 is equipped with a safety valve 18 consisting of a valve body, a steel ball, and a spring. During use, when the pressure in the high-temperature and high-pressure dissolution tank 3 exceeds the compression force of the safety valve spring, the gas in the high-temperature and high-pressure dissolution tank 3 pushes the steel ball to be discharged outside the high-temperature and high-pressure dissolution tank 3, thus providing a safety function. The pressure in the high-temperature and high-pressure dissolution tank 3 can be adjusted. When there is pressure in the high-temperature and high-pressure dissolution tank 3, the sealing cover 13 is firmly fixed to the base 17 and cannot be opened.

[0048] Preferably, the high-precision flow measurement and controller 2 is an RS485 digital display high-precision gas flow measurement and controller (Shanghai Jishen Instrument Co., Ltd.).

[0049] A test method using the formate buffer solution gas intrusion resistance test device comprises the following steps:

[0050] S1: introducing the formate buffer system into the high temperature and high pressure dissolution tank 3;

[0051] S2: Using pH measuring unit 5 to measure the initial pH value of the formate buffer system;

[0052] S3: Turn on the high-precision flow measurement controller 2, connect the high-purity N2 gas cylinder, set the high-precision flow measurement controller 2, and make the high-purity N2 gas flow into the high-temperature and high-pressure dissolution tank 3 at a fixed flow rate for at least 1 hour to fully remove the O2 in the solution tank;

[0053] S4: Turn on the high-precision flow measurement controller 2, connect the high-purity CO2 gas cylinder, and set the high-precision flow measurement controller 2 so that the high-purity CO2 gas invades the high-temperature and high-pressure dissolution tank at a fixed flow rate;

[0054] S5: Turn on the pH measuring unit and regularly measure the pH value of the formate buffer system;

[0055] S6: Turn on the smart camera and regularly record the readings of the pH measurement unit 5;

[0056] S7: Draw a curve of pH value of the formate buffer system versus CO2 flow rate, where the ordinate of the curve is the pH value of the solution measured regularly during the test, and the abscissa of the curve is the CO2 flow rate introduced during the test (CO2 flow rate × time).

[0057] S8: Analyze the pH-CO2 inlet flow rate curve for the formate buffer system to determine the CO2 content required to enter the system at the lowest pH value permitted on-site under different buffer composition and dosage conditions. This allows the optimal buffer composition and dosage to be screened. The CO2 content at which the pH value stabilizes after continuous CO2 infusion is determined when the optimal buffer composition and dosage are added. This is the CO2 limit infusion rate.

[0058] Example 1

[0059] like Figure 1 The formate buffer solution gas intrusion resistance test device provided by the present invention comprises a gas injection system 1, a high-precision flow measurement and control meter 2, a high-temperature and high-pressure dissolution tank 3, an exhaust system 4, a pH measurement unit 5, and a data monitoring system 6. The gas injection system 1, the high-precision flow measurement and control meter 2, the high-temperature and high-pressure dissolution tank 3, the exhaust system 4, and the pH measurement unit 5 are sequentially connected by pipelines.

[0060] The gas injection system 1 provides a gas source. After the gas enters the high-precision flow measurement controller 2, it invades the high-temperature and high-pressure dissolution tank 3 at a set flow rate, and is then discharged from the exhaust system 4 at a set flow rate.

[0061] The high-precision flow measurement controller 2 is connected to the gas injection system 1 and the high-temperature and high-pressure dissolution tank 3 through pipelines, so that the gas invades the high-temperature and high-pressure dissolution tank 3 at a set flow rate with a pressure of not less than 1.2KPa.

[0062] The high-temperature and high-pressure dissolution tank 3 consists of a solution tank body 7, a solution tank liner 8, a transparent hollow layer 9 and a sealing cover 13. The transparent hollow layer 9 is filled with a heat-insulating material 10, which has a good heat-insulating effect. The solution tank body 7 is provided with a first hole 11 and a second hole 12, which are convenient for filling the heat-insulating material. A temperature detector 14 is installed on the side of the outer wall of the solution tank liner to detect the temperature of the formate buffer system in real time. A heater 15 is installed at the bottom of the outer wall of the solution tank liner to heat the formate buffer system. The controller 16 is located in the transparent hollow layer 9 and is connected to the temperature detector 14 and the heater 15 through pipelines for controlling the heating. The heater heats the formate buffer system, and the switch button of the controller 16 is exposed outside the solution tank body 7 for easy operation; the sealing cover 13 and the base 17 are fixed by threads, and have good airtightness; the high-temperature and high-pressure dissolution tank 3 is connected to the pH measurement unit 5 and the exhaust system 4 through pipelines, and the connections are fixed with threads and sealing rings to ensure good sealing; the sealing cover 13 of the high-temperature and high-pressure dissolution tank 3 is equipped with a safety valve 18. When the pressure in the high-temperature and high-pressure dissolution tank is too high, the gas is discharged through the safety valve 18 to play a safety role; the high-temperature and high-pressure dissolution tank 3 is equipped with a pressure detector 19 to detect the pressure in the high-temperature and high-pressure dissolution tank in real time.

[0063] The exhaust system 4 is connected to the high-temperature and high-pressure dissolution tank 3 through a pipeline, and the connection is fixed with threads and sealing rings to ensure good sealing; the exhaust system 4 controls the gas discharge at a set flow rate to ensure the stability of the pressure in the high-temperature and high-pressure dissolution tank 3.

[0064] The electrode of the pH measuring unit 5 penetrates the sealing cover 13 and enters the high-temperature and high-pressure dissolution tank. The electrode probe is in full contact with the formate buffer system. The connection between the electrode and the sealing cover 13 is fixed by threads and a sealing ring to ensure a good seal.

[0065] The data monitoring system 6 monitors the pH measurement unit reading in real time and stores the monitoring data.

[0066] The test steps using this device are as follows:

[0067] S1: introducing the formate buffer system into the high temperature and high pressure dissolution tank;

[0068] S2: Measure the initial pH value of the formate buffer system using a pH measuring cell;

[0069] S3: Turn on the high-precision flow measurement controller, connect the high-purity N2 gas cylinder, set the high-precision flow measurement controller, and allow the high-purity N2 gas to infiltrate the high-temperature and high-pressure dissolution tank at a fixed flow rate for at least 1 hour to fully remove the O2 in the solution tank;

[0070] S4: Turn on the high-precision flow measurement controller, connect the high-purity CO2 gas cylinder, and set the high-precision flow measurement controller to allow the high-purity CO2 gas to infiltrate the high-temperature and high-pressure dissolution tank at a fixed flow rate;

[0071] S5: Turn on the pH measuring unit and regularly measure the pH value of the formate buffer system;

[0072] S6: Turn on the smart camera and regularly record the pH measurement unit readings;

[0073] S7: Draw a curve of pH value of formate buffer system versus CO2 flow rate. The vertical axis of the curve is the pH value of the solution measured regularly during the test, and the horizontal axis of the curve is the CO2 flow rate (CO2 flow rate × time) during the test. Figure 2 As shown;

[0074] S8: Obtain the CO2 content introduced at the lower limit of the pH value allowed on site under different buffer composition and addition conditions through the formate buffer system pH value-CO2 inlet flow rate curve, thereby screening out the optimal buffer composition and addition amount. At the same time, obtain the lowest pH value after continuous CO2 introduction and the CO2 content after it begins to maintain stability when adding the optimal composition and addition amount of buffer, which is the CO2 limit gas intrusion amount; Figure 2 As shown, in the absence of a buffer or with the addition of NaOH / Na2CO3 to adjust the pH to 11, the pH of the formate solution decreased significantly with increasing CO2 intrusion levels. The resistance to CO2 intrusion gradually improved with increasing Na2CO3-NaHCO3 ratios (more Na2CO3). As the Na2CO3-NaHCO3 ratio increased (5:5 → 5:1), the amount of CO2 dissolved in the buffered formate solution increased as the pH decreased. The resistance to CO2 intrusion was highest at 5:1, followed by 5:2.

Claims

1. A formate buffer solution gas intrusion resistance testing device, characterized in that: The invention comprises a high-temperature and high-pressure dissolution tank (3) for containing a formate buffer solution, wherein the air inlet of the high-temperature and high-pressure dissolution tank (3) is connected to the outlet of the gas injection system (1) through a high-precision flow measurement controller (2) for controlling the flow of CO2 entering the high-temperature and high-pressure dissolution tank (3), the air outlet of the high-temperature and high-pressure dissolution tank (3) is connected to the inlet of the exhaust system (4), a pH measuring unit (5) is sealedly connected to the high-temperature and high-pressure dissolution tank (3), a measuring end of the pH measuring unit (5) extends into the high-temperature and high-pressure dissolution tank (3) for regularly detecting the pH value of the formate buffer solution, and a display end of the pH measuring unit (5) is connected to a data monitoring system (6) for obtaining the pH value of the formate buffer solution in real time.

2. A formate buffer solution gas intrusion resistance testing device according to claim 1, characterized in that: The high-temperature and high-pressure dissolution tank (3) comprises a solution tank body (7), a sealing cover (13), a temperature detector (14), a heater (15) and a pressure detector (19); the sealing cover (13) is sealed at an opening of the solution tank body (7); a plurality of openings are provided on the sealing cover (13); an exhaust system (4), a high-precision flow measurement controller (2) and a pH measurement unit (5) are sealedly connected to the sealing cover (13) through the openings; the temperature detector (14) and the heater (15) are provided in the solution tank body (7); and the pressure detector (19) is provided on the sealing cover (13).

3. A formate buffer solution gas intrusion resistance testing device according to claim 2, characterized in that: An inner liner (8) is provided in the solution pool body (7), a transparent hollow layer (9) is provided between the inner liner (8) and the solution pool body (7), the transparent hollow layer (9) is used to be filled with a heat insulating material (10), a temperature detector (14) and a heater (15) are both provided on the outer wall of the inner liner (8), and the temperature detector (14), the heater (15) and a controller (16) are connected to realize the detection of the temperature of the formate buffer system and the control of the power of the heater.

4. A formate buffer solution gas intrusion resistance testing device according to claim 2, characterized in that: A base (17) is fixed at the lower end of the high-temperature and high-pressure dissolution tank (3), and the base (17) is fixedly connected to the sealing cover (13).

5. A formate buffer solution gas intrusion resistance testing device according to claim 2, characterized in that: A safety valve (18) is also provided on the sealing cover (13) for regulating the pressure of the high-temperature and high-pressure dissolution tank (3).

6. A formate buffer solution gas intrusion resistance testing device according to claim 1, characterized in that: The exhaust system (4) is a high-pressure exhaust sealing valve assembly; the pH measurement unit (5) is a laboratory pH meter or a portable pH meter; and the data monitoring system (6) is a digital camera.

7. A formate buffer solution gas intrusion resistance testing device according to claim 1, characterized in that: The gas injection system (1) comprises a first gas injection device and a second gas injection device, wherein the first gas injection device is an inert gas injection device and the second gas injection device is a CO2 gas injection device.

8. A method for testing the gas intrusion resistance of a formate buffer solution, characterized in that: The test device according to any one of claims 1 to 7 is carried out, and the specific steps are as follows: S1 introduces the formate buffer system into the high-temperature and high-pressure dissolution tank (3), and uses the pH measurement unit (5) to measure the initial pH value of the formate buffer system; S2 connects the first gas injection device and the second gas injection device of the gas injection system (1) to the high-precision flow measurement controller (2), sets the flow rates of the first gas injection and the second gas injection, first injects the first gas injection at a fixed flow rate into the high-temperature and high-pressure dissolution tank (3) for deoxygenation, and then injects the second gas injection at a fixed flow rate into the high-temperature and high-pressure dissolution tank (3); S3 pH measurement unit (5) regularly measures the pH value of the formate buffer system in the high temperature and high pressure dissolution tank (3); The S4 data monitoring system (6) obtains the pH value of the formate buffer system in the high-temperature and high-pressure dissolution tank (3), and establishes a formate buffer system pH value-second gas injection flow rate curve using the pH value of the formate buffer system and the set second gas injection flow rate; S5 obtains the CO2 limit gas intrusion volume under different buffer components and addition conditions based on the pH value-second gas injection flow rate curve of the formate buffer system.

9. A method for testing the gas intrusion resistance of a formate buffer solution according to claim 8, characterized in that: In S2, the temperature of the high-temperature and high-pressure dissolution tank (3) is from room temperature to 300°C, and the pressure is from normal pressure to 100 MPa.

10. The method for testing the gas intrusion resistance of a formate buffer solution according to claim 8, wherein: In S2, the first gas injection and the second gas injection are injected into the high temperature and high pressure dissolution tank (3) at a pressure of not less than 1.2 KPa.

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