An experimental device suitable for corrosion of metal pipe materials

Abstract

The invention belongs to the technical field of oil and gas exploitation, and specifically provides an experimental device suitable for metal pipe column material corrosion, comprising N 2 Gas source, fluid replenishment unit, CO 2 Gas circuit unit, mixing device, high temperature and high pressure corrosion experimental device unit and supercritical fluid chromatography analysis unit, outlet of liquid replenishment unit and CO 2 The outlet of the gas circuit unit is connected to the inlet of the mixing device, and the outlet of the mixing device is connected to N 2 The outlet of the gas source is connected to the inlet of the high temperature and high pressure corrosion experimental device unit, and the supercritical fluid chromatography analysis unit is connected to the high temperature and high pressure corrosion experimental device unit, which solves the problem of studying supercritical CO in the prior art. 2 When the fluid affects the corrosion of the metal pipe string, the phase change problem is not involved, and the corrosion problem of the pipe string in the actual production conditions cannot be truly and accurately evaluated. The present invention can more truly and accurately evaluate the safety performance of the pipe string in the actual production conditions, and can also be used for in-depth research on the corrosion mechanism and the evaluation of supporting anti-corrosion measures.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploitation, and in particular relates to an experimental device suitable for metal pipe column material corrosion. Background Art

[0002] Using supercritical CO 2 The high density, low viscosity, strong diffusion and strong solubility of the fluid can be used for CO2 treatment of low porosity (porosity < 10%), low permeability (permeability < 1md) and heterogeneous reservoirs. 2 Compared with water injection, displacement can further improve the recovery rate; in fact, in CO 2 During the oil recovery process test, liquid CO 2 Through the booster pump injection into the wellbore, as the formation temperature rises, CO 2 The fluid reaches a supercritical state in a certain section of the wellbore, and after being injected into the reservoir, it forms a miscible phase with the crude oil in the rock pores, effectively displacing the oil by reducing density and interfacial tension. However, in order to control the mobility ratio, the supercritical CO 2 The sweep coefficient is reduced, the gas emergence time is delayed, and WAG water-gas alternation (i.e., water slug and gas slug are injected alternately) is adopted. This process directly leads to supercritical CO 2 It contacts with the retained water in the formation and dissolves to form a corrosion electrolytic cell, which causes electrochemical corrosion to the metal pipe column. 2 After reaching the supercritical state, the solubility in water, ion diffusion rate, and electrochemical reaction rate all increase with increasing pressure. 2 / H 2 The corrosion of metal pipes by O system is more serious than that of low partial pressure CO 2 Acid corrosion is more serious, causing failure behaviors such as corrosion perforation and stress corrosion cracking of metal pipes, which can easily cause engineering problems such as gas channeling, directly affecting production safety and restricting CO 2 Therefore, in-depth research on different phases of CO 2 / H 2 The corrosion mechanism of pipe strings in O environment has important engineering guidance significance for the formulation of anti-corrosion measures in the subsequent construction process.

[0003] In CO 2 During the oil displacement experiment, CO 2 The fluid is not in a single phase, and the working conditions are complex and changeable: ① In underground working conditions, CO 2 , crude oil and formation water form CO under the action of miscibility and dissolution. 2 / H 2 O / Oil mixed system, CO 2 / H 2 The O system itself is corrosive, and crude oil is also corrosive to a certain extent because it contains sulfides or has a low acid value. 2 / H 2 The O / oil mixed system increases the complexity of its corrosion behavior on metal pipes; ②CO 2 / H 2 CO in O system 2 The solubility in water changes dynamically with the ambient temperature and pressure. 2 The water content of the water phase will also change, which will cause different degrees of corrosion; ③ In the entire CO 2 During the oil recovery process, as the pressure, temperature and other influencing factors change, CO 2 The fluid is also in noncritical CO 2 , subcritical CO 2 , supercritical CO 2 The corrosion conditions of the metal pipe column are non-critical CO 2 (Fu H 2 O phase + CO rich 2 phase), subcritical CO 2 (Fu H 2 O phase + CO rich 2 phase), supercritical CO 2 (Fu H 2 O phase + CO rich 2 There are at least 6 types of corrosion, and the severity and mechanism of corrosion vary greatly under different working conditions.

[0004] The harsh and complex wellbore working conditions have put forward higher requirements for corrosion simulation experimental equipment and corrosion experimental methods. 2 There are many research contents on the corrosion behavior of sour gas fields, and a large number of research results have been produced. However, in recent years, 2 The corrosion problems associated with the development of oil recovery technology have been less studied, and there are even fewer applicable metal pipe column corrosion evaluation methods. The existing methods mostly use high-temperature and high-pressure autoclaves for weight loss simulation, which has the following problems: ① The existing technology mainly studies supercritical CO 2 The influence of fluid corrosion does not involve the problem of phase change. Different phases have different effects on corrosion rate and electrochemical process. It is impossible to conduct systematic research using existing equipment and methods. 2 The injection and production environment is complex, and the medium composition is CO 2 The mixed system of fluid, crude oil and high-ore formation water, after forming a mixed phase, is affected by changes in temperature and pressure, and the water content and CO 2 The fluid density value will also change, and the corrosion test results will also be different. The existing technology has not conducted a systematic classification simulation study and cannot accurately evaluate the safety performance of the pipe string material under simulated working conditions; ③ The existing technology is limited by the device design and cannot accurately simulate the non-critical CO 2 (Fu H 2 O phase + CO rich2 phase), subcritical CO 2 (Fu H 2 O phase + CO rich 2 phase), supercritical CO 2 (Fu H 2 O phase + CO rich 2 Therefore, it is necessary to develop a simulation method for CO 2 CO in flooding and injection production environment 2 / H 2 Experimental device for evaluating corrosion of metal pipe materials corresponding to phase changes in the O system. Summary of the invention

[0005] The experimental device for metal pipe column corrosion provided by the present invention aims to overcome the existing technology of studying supercritical CO 2 When the fluid affects the corrosion of the metal pipe column, the phase change problem is not involved, and the existing equipment and methods cannot be used for systematic research; the second purpose is to overcome the CO 2 The injection and production environment is complex, and the medium composition is CO 2 The mixed system of fluid, crude oil and high-ore formation water, after forming a mixed phase, is affected by changes in temperature and pressure, and the water content and CO 2 The fluid density value will also change, resulting in different corrosion test results. The existing technology has not conducted systematic classification simulation research and cannot accurately evaluate the safety performance of the pipe string material under simulated working conditions. The third purpose is to overcome the limitations of the existing technology due to the design of the device and cannot accurately simulate the non-critical CO 2 (Fu H 2 O phase + CO rich 2 phase), subcritical CO 2 (Fu H 2 O phase + CO rich 2 phase), supercritical CO 2 (Fu H 2 O phase + CO rich 2 Therefore, it is necessary to develop a simulation method for CO 2 CO in flooding and injection production environment 2 / H 2 Problems with the experimental device for evaluating the corrosion of metal pipe materials corresponding to the phase changes of the O system.

[0006] To this end, the present invention provides an experimental device suitable for metal pipe column material corrosion, including N 2 Gas source, fluid replenishment unit, CO 2 Gas circuit unit, mixing device, high temperature and high pressure corrosion experiment device unit, supercritical fluid chromatography analysis unit and automatic potentiometric titration unit, outlet of liquid replenishment unit and CO 2The outlet of the gas circuit unit is connected to the inlet of the mixing device, and the outlet of the mixing device is connected to N 2 The outlets of the gas sources are connected to the inlets of the high-temperature and high-pressure corrosion experiment device units, the gas outlets of the high-temperature and high-pressure corrosion experiment device units are connected to the supercritical fluid chromatography analysis unit, and the liquid outlets of the high-temperature and high-pressure corrosion experiment device units are connected to the automatic potentiometric titration unit.

[0007] The N 2 The gas source is high-purity N with a purity of 99.99% 2 .

[0008] The rehydration unit comprises a rehydration tank and an injection pump, and the rehydration tank is connected to the inlet of the mixing device through the injection pump.

[0009] A mixed liquid of crude oil and water is added into the liquid replenishment tank.

[0010] The CO 2 Gas circuit unit includes CO 2 Gas source, temperature control device and constant flow metering plunger pump, CO 2 The inlets of the gas source, the temperature control device, the constant flow metering plunger pump and the mixing device are connected in sequence.

[0011] The CO 2 The gas source is 99.99% high purity CO2.

[0012] The temperature control device adopts two temperature control modes: electric heating and Freon cooling.

[0013] The high temperature and high pressure corrosion experimental device unit comprises a temperature and liquid level control device, a heating temperature control device, a stirrer, an alloy kettle cavity, a multi-layer coupon corrosion fixture, a gas phase environment corrosion coupon, a liquid phase environment corrosion coupon, a bottom probe tube and a pressure sensor. The temperature and liquid level control device and the sensing ends of the pressure sensor are both connected to the interior of the alloy kettle cavity. The side of the alloy kettle cavity is connected to the heating temperature control device. An observation window is provided in the front of the alloy kettle cavity. The stirring shaft of the stirrer penetrates into the interior of the alloy kettle cavity and is connected to the multi-layer coupon corrosion fixture. The upper layer of the multi-layer coupon corrosion fixture is connected to the gas phase environment corrosion coupon, which is located in the gas phase layer in the alloy kettle cavity. The lower layer of the multi-layer coupon corrosion fixture is connected to the liquid phase environment corrosion coupon, which is located in the liquid phase layer in the alloy kettle cavity. 2 The outlets of the gas source and the mixing device are merged through a pipeline and then connected to the interior of the alloy kettle chamber in two ways, wherein the lower end of one pipeline is located in the gas phase layer in the alloy kettle chamber, and the other pipeline is connected to a bottom probe tube and the lower end of the bottom probe tube is located in the liquid phase layer in the alloy kettle chamber; a liquid discharge port is provided at the bottom of the alloy kettle chamber.

[0014] The supercritical fluid chromatography analysis unit comprises a fidelity sampler, a supercritical fluid chromatography analyzer and a PC control device. The outlet of the alloy kettle cavity is connected to the supercritical fluid chromatography analyzer through the fidelity sampler, and the PC control device is electrically connected to the alloy kettle cavity and the supercritical fluid chromatography analyzer respectively.

[0015] The automatic potentiometric titration unit comprises a liquid storage tank, a titration cell, a potential indicator electrode and an automatic titration device. The liquid discharge port of the alloy kettle cavity is connected to the titration cell through the liquid storage tank. One end of the potential indicator electrode and one end of the automatic titration device are both connected to the liquid phase layer in the titration cell. The other end of the potential indicator electrode and the other end of the automatic titration device are both electrically connected to a PC control device.

[0016] Beneficial effects of the present invention:

[0017] 1. The experimental device for metal pipe column corrosion provided by the present invention fully considers the CO 2 The real working conditions during the injection and production process, the introduction of the fluid replenishment unit, through the CO 2 Gas circuit unit realizes supercritical CO 2 fluid, and CO is mixed by a mixing device (7) 2 Supercritical CO achieved by gas circuit unit 2 The fluid forms a mixture with the crude oil and formation water in the fluid replenishment unit; the mixture is input into the high temperature and high pressure corrosion test device unit to accurately control the dynamic changes of temperature, pressure and corrosive medium, so as to accurately simulate the non-critical CO 2 (Fu H 2 O phase + CO rich 2 phase), subcritical CO 2 (Fu H 2 O phase + CO rich 2 phase), supercritical CO 2 (Fu H 2 O phase + CO rich 2 According to the simulated corrosion conditions, the safety performance of the pipe string material under the simulated conditions can be accurately evaluated;

[0018] 2. The experimental device for metal column corrosion of the present invention introduces a supercritical fluid chromatography analysis unit, collects synchronously through a fidelity sampler, and connects to a supercritical fluid chromatography analysis to measure the CO in the alloy reactor cavity. 2 Water content and CO 2 The fluid density value is adjusted according to the data feedback value to adjust the environment inside the alloy reactor chamber;

[0019] 3. The experimental device for metal column corrosion of the present invention introduces an automatic potentiometric titration unit, and a certain volume of liquid is pumped into the titration cell by a peristaltic pump or other automatic sampling device. The PC control device controls the potential indicator electrode and the automatic titration device to measure the CO in the solution in the liquid phase of the titration cell. 3 2- or HCO 3 - concentration; to achieve the CO dissolved in the corrosive medium in the high temperature and high pressure reactor chamber 2 , and CO 2 Converted to CO 3 2- / HCO 3 - Concentration detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described in detail below with reference to the accompanying drawings.

[0021] Figure 1 It is a schematic diagram of the structure of an experimental device suitable for corrosion of metal pipe materials.

[0022] Description of reference numerals: 1, N 2 Gas source; 2. Fluid replenishment tank; 3. Injection pump; 4. CO 2 Gas source; 5. Temperature control device; 6. Constant flow metering plunger pump; 7. Mixing device; 8. Temperature and liquid level control device; 9. Heating temperature control device; 10. Agitator; 11. Strong corrosion resistant alloy kettle chamber; 12. Multilayer hanging piece corrosion fixture; 13. Gas phase environment corrosion hanging piece; 14. Liquid phase environment corrosion hanging piece; 15. Bottom tube; 16. Observation window; 17. Pressure sensor; 18. Fidelity sampler; 19. Supercritical fluid chromatograph; 20. PC control device; 21. Liquid storage tank; 22. Titration cell; 23. Potential indicator electrode; 24. Automatic titration device. DETAILED DESCRIPTION

[0023] Embodiment 1:

[0024] like Figure 1 As shown in FIG. 1 , an experimental device suitable for metal pipe column material corrosion includes N 2 Gas source 1, fluid replenishment unit, CO 2 Gas circuit unit, mixing device 7, high temperature and high pressure corrosion experimental device unit, supercritical fluid chromatography analysis unit and automatic potentiometric titration unit, outlet of liquid replenishment unit and CO 2 The outlet of the gas circuit unit is connected to the inlet of the mixing device 7, and the outlet of the mixing device 7 is connected to the N 2The outlets of the gas source 1 are connected to the inlet of the high temperature and high pressure corrosion experiment device unit, the gas outlet of the high temperature and high pressure corrosion experiment device unit is connected to the supercritical fluid chromatography analysis unit, and the liquid outlet of the high temperature and high pressure corrosion experiment device unit is connected to the automatic potentiometric titration unit.

[0025] The experimental device for metal pipe column corrosion provided by the present invention fully takes into account the CO 2 The real working conditions during the injection and production process, the introduction of the fluid replenishment unit, through the CO 2 Gas circuit unit realizes supercritical CO 2 fluid, and CO is mixed by the mixing device 7 2 Supercritical CO achieved by gas circuit unit 2 The fluid forms a mixture with the crude oil and formation water in the fluid replenishment unit; the mixture is input into the high temperature and high pressure corrosion test device unit and the temperature, pressure and dynamic changes of the corrosive medium are precisely controlled to achieve accurate simulation of non-critical CO 2 (Fu H 2 O phase + CO rich 2 phase), subcritical CO 2 (Fu H 2 O phase + CO rich 2 phase), supercritical CO 2 (Fu H 2 O phase + CO rich 2 According to the simulated corrosion conditions, the safety performance of the pipe string material under the simulated conditions can be accurately evaluated.

[0026] Embodiment 2:

[0027] On the basis of Example 1, further, the N 2 Gas source 1 is high purity N with a purity of 99.99% 2 .

[0028] N 2 Gas source 1 is directly connected to the high temperature and high pressure corrosion test device unit through a valve, N 2 After the gas source 1 is connected to the air inlet of the alloy kettle chamber 11, it can be used to displace the impurity gas in the alloy kettle chamber 11 before the corrosion experiment and displace the dissolved oxygen gas in the corrosive medium after the corrosive medium is added, reducing the dissolved oxygen content to the experimental requirements and preventing oxygen corrosion. High purity N with a purity of 99.99% 2 Medium 2 ≤0.01%, avoid the entry of additional oxygen when displacing dissolved oxygen in corrosive media. 2 Improve the accuracy of your experiments.

[0029] Further, the rehydration unit includes a rehydration tank 2 and an injection pump 3, and the rehydration tank 2 is connected to the inlet of the mixing device 7 via the injection pump 3. The injection pump 3 is convenient for injecting the liquid in the rehydration tank 2 into the mixing device 7, and has a simple structure.

[0030] Furthermore, a mixture of crude oil and water is added to the liquid replenishment tank 2. The mixture of crude oil and water is used to provide materials as needed, and then mixed with CO in the mixing device 7. 2 Supercritical CO achieved by gas circuit unit 2 Fluids are mixed to achieve supercritical CO 2 / Crude Oil / H 2 O mixed solution.

[0031] Furthermore, the CO 2 Gas circuit unit includes CO 2 Gas source 4, temperature control device 5 and constant flow metering plunger pump 6, CO 2 The gas source 4, the temperature control device 5, the constant flow metering plunger pump 6 and the inlet of the mixing device 7 are connected in sequence. The temperature control device 5 adopts two temperature control modes: electric heating and Freon cooling.

[0032] CO 2 The gas source 4 is connected to the temperature control device 5 through a valve. The temperature control device 5 includes two temperature control modes: electric heating and Freon cooling, which can accurately control the CO 2 Gas temperature, accuracy ±1℃, CO can be reduced according to experimental requirements 2 The temperature is controlled at 0-100°C. The temperature control device 5 is selected from an existing temperature control device according to actual conditions, and its specific structure is not introduced here. The CO2 gas source 4 is connected to the constant flow metering plunger pump 6 after being heated by the temperature control device 5. The constant flow metering plunger pump (6) has a pressure range of 0-20MPa, which can pressurize CO2 to a supercritical state and deliver it to the mixing device 7 at a constant flow rate.

[0033] Furthermore, the CO 2 Gas source 4 is 99.99% high purity CO 2 99.99% high purity CO 2 Medium 2 ≤0.01%, making supercritical CO 2 The fluid contains almost no oxygen, which improves the accuracy of the experiment.

[0034] Embodiment 3:

[0035] On the basis of Example 2, further, the high temperature and high pressure corrosion experimental device unit includes a temperature and liquid level control device 8, a heating temperature control device 9, a stirrer 10, an alloy kettle cavity 11, a multi-layer coupon corrosion fixture 12, a gas phase environment corrosion coupon 13, a liquid phase environment corrosion coupon 14, a bottom probe 15 and a pressure sensor 17, the temperature and liquid level control device 8 and the sensing end of the pressure sensor 17 are connected to the inside of the alloy kettle cavity 11, the side of the alloy kettle cavity 11 is connected to the heating temperature control device 9, the front (front wall) of the alloy kettle cavity 11 is provided with an observation window 16, the stirring shaft of the stirrer 10 penetrates into the alloy kettle cavity 11 and is connected to the multi-layer coupon corrosion fixture 12, the upper layer of the multi-layer coupon corrosion fixture 12 is connected to the gas phase environment corrosion coupon 13, the gas phase environment corrosion coupon 13 is located in the gas phase layer in the alloy kettle cavity 11, the lower layer of the multi-layer coupon corrosion fixture 12 is connected to the liquid phase environment corrosion coupon 14, the liquid phase environment corrosion coupon 14 is located in the liquid phase layer in the alloy kettle cavity 11, N 2 The outlets of the gas source 1 and the mixing device 7 are merged through a pipeline and then connected to the interior of the alloy kettle chamber 11 in two ways, wherein the lower end of one pipeline is located in the gas phase layer in the alloy kettle chamber 11, and the other pipeline is connected to the bottom probe tube 15 and the lower end of the bottom probe tube 15 is located in the liquid phase layer in the alloy kettle chamber 11; a liquid discharge port is provided at the bottom of the alloy kettle chamber 11.

[0036] Supercritical CO in mixing device 7 2 / Crude Oil / H 2 O mixture (corrosive medium) is connected to the air inlet of the alloy kettle chamber 11, and enters the upper gas phase environment and the lower liquid phase environment of the alloy kettle chamber 11 respectively. The gas phase environment corrosion hanging piece 13 is located in the gas phase layer of the alloy kettle chamber 11, so that the gas phase environment corrosion hanging piece 13 is in the supercritical CO 2 / H 2 O system (rich CO 2 phase) medium, the liquid phase environment corrosion hanging piece 14 is located in the liquid phase layer in the alloy kettle chamber 11, so that the liquid phase environment corrosion hanging piece 14 is in the supercritical CO 2 / H 2 O system (rich H 2O phase) medium. The heating temperature control device 9 heats the alloy kettle cavity 11 and controls its temperature. The temperature and liquid level control device 8 realizes the accurate measurement and storage of the medium temperature and liquid level height in the alloy kettle cavity 11, and can transmit the data to the PC control device in real time. Specifically, during the implementation of the experiment, the liquid level height can be controlled in the following three ways to ensure that the corrosive medium around the corrosion test piece is the preset corrosive environment of the experiment: ① Observe the change of the liquid level in the alloy kettle cavity 11 in real time through the observation window 16, and open or close the liquid replenishment tank or the drain port; ② Automatically identify the prompt through the temperature and liquid level control device 8, open or close the liquid replenishment tank or the drain port; ③ Use the temperature and liquid level control device 8 to automatically identify the prompt, and match the single-way solenoid valve component to realize the PC-side software to automatically open or close the liquid replenishment tank or the drain port. The temperature and liquid level control device 8 is an existing device, including a temperature sensor and a liquid level detector; the pressure sensor 17 monitors the internal pressure of the alloy kettle chamber 11 in real time, and adjusts the pressure in the alloy kettle chamber 11 at any time according to the monitoring situation to meet the experimental requirements; the agitator 10 drives the multi-layer coupon corrosion fixture 12 to rotate axially, and simulates the dynamic working conditions of the metal pipe string in the well through the angular velocity. The high temperature and high pressure corrosion experimental device unit can accurately simulate the CO 2 Injection and production environment, even if the medium composition is CO 2 The mixed system of fluid, crude oil and high-ore formation water, after forming a mixed phase, is affected by changes in temperature and pressure, and the water content and CO 2 The fluid density value will also change. The high temperature and high pressure corrosion experimental device unit can also accurately simulate, conduct systematic classification simulation research, and accurately evaluate the safety performance of the pipe string material under simulated working conditions. The observation window 16 is convenient for observing the corrosive medium in the alloy reactor chamber 11. The bottom probe 15 is introduced to ensure that CO 2 Liquids such as fluids or corrosion inhibitors can be fully dissolved in the liquid corrosive medium in the kettle cavity.

[0037] A drain port is provided at the bottom of the alloy kettle chamber 11; when the amount of liquid replenishment is large and the corrosive medium page rises, the liquid replenishment should be stopped and the liquid should be drained from the bottom of the alloy kettle chamber 11 to ensure the stability of the experimental environment of the gas phase environment corrosion hanging piece 13 and the liquid phase environment corrosion hanging piece 14.

[0038] Furthermore, the outside of the observation window 16 is provided with scale lines, which facilitates accurate measurement of the water level of the liquid medium in the alloy kettle chamber 11, and thus accurate filling of the medium.

[0039] The method for simulating the six phases is as follows: spatial stratification (gas phase layer and liquid phase layer) in the alloy reactor chamber 11 + stratification of the corrosive medium + stratification of the corrosion fixture (upper gas phase environment corrosion hanging piece 13 and lower liquid phase environment corrosion hanging piece 14), the upper corrosive medium is supercritical CO 2 Dissolved oil-bearing formation water (on-site sampling), dissolved CO in the lower formation water 2, in addition, when CO 2 When the supercritical state is not reached (i.e., non-critical and subcritical phases), the miscible phase cannot be formed. 2 The temperature and pressure phase change diagram determines the critical point. By setting the temperature and pressure values, CO 2 They are in non-critical, subcritical and supercritical phases respectively, and after mixing with formation water, they are respectively introduced into the upper and lower spaces of the reactor chamber.

[0040] Furthermore, the number of the gas phase environment corrosion hanging plates 13 and the liquid phase environment corrosion hanging plates 14 are both multiple, and the multiple gas phase environment corrosion hanging plates 13 are connected to the upper layer of the multi-layer hanging plate corrosion fixture 12 at equal intervals in the circumferential direction, and the multiple liquid phase environment corrosion hanging plates 14 are connected to the lower layer of the multi-layer hanging plate corrosion fixture 12 at equal intervals in the circumferential direction; this structure ensures that the axial rotation force of the agitator (10) is balanced, and at the same time, the multiple gas phase environment corrosion hanging plates 13 and the liquid phase environment corrosion hanging plates 14 can provide multiple experimental samples, thereby improving the accuracy of the experiment.

[0041] Furthermore, the temperature and liquid level control device 8 and the alloy kettle chamber 11 are both made of corrosion-resistant materials; the corrosion-resistant materials are selected from existing materials according to actual conditions and are not specifically limited here, so as to improve the service life of the device and equipment.

[0042] Furthermore, the stirrer 10 is a high-torque magnetically driven mechanical stirrer. Since the internal magnetic steel body and the stirring shaft of the high-torque magnetically driven mechanical stirrer are installed inside the sealing cover, and the plane between the sealing cylinder and the kettle body can be tightened by bolts with a metal graphite pad, the "dynamic seal" between the stirring shaft and the kettle body is fundamentally changed to a "static seal", thereby achieving no leakage under high temperature and high pressure, and improving the accuracy of the experiment.

[0043] Example 4

[0044] On the basis of Example 3, further, the supercritical fluid chromatography analysis unit includes a fidelity sampler 18, a supercritical fluid chromatography analyzer 19 and a PC control device 20. The outlet of the alloy kettle chamber 11 is connected to the supercritical fluid chromatography analyzer 19 through the fidelity sampler 18. The PC control device 20 is electrically connected to the alloy kettle chamber 11 and the supercritical fluid chromatography analyzer 19. The experimental device suitable for metal column material corrosion of the present invention is connected to the supercritical fluid chromatography analyzer 19 to measure the CO in the alloy kettle chamber. 2 Water content and CO 2 The fluid density value changes according to the data feedback value, and the environment inside the alloy reactor cavity is adjusted.

[0045] Furthermore, the automatic potentiometric titration unit includes a liquid storage tank 21, a titration cell 22, a potential indicator electrode 23 and an automatic titration device 24. The discharge port of the alloy kettle chamber 11 is connected to the titration cell 22 through the liquid storage tank 21. One end of the potential indicator electrode 23 and one end of the automatic titration device 24 are both connected to the liquid phase layer in the titration cell 22. The other end of the potential indicator electrode 23 and the other end of the automatic titration device 24 are both electrically connected to the PC control device 20.

[0046] The working principle of the automatic potentiometric titration unit is as follows: the discharge port of the alloy kettle chamber 11 is connected to the liquid storage tank 21, a certain volume of liquid is pumped into the titration cell 22 through a peristaltic pump or other automatic sampling device, and the PC control device 20 controls the potential indicator electrode 23 and the automatic titration device 24 to measure the CO in the solution. 3 2- or HCO 3 - concentration; to achieve the CO dissolved in the corrosive medium in the high temperature and high pressure reactor chamber 2 , and CO 2 Converted to CO 3 2- / HCO 3 - The automatic titration device 24 is an existing device with an automatic titration function, and its structure will not be described in detail here.

[0047] CO 2 and H 2 O mixed phase moisture content and CO 2 The density directly affects the corrosion rate of the metal specimen. The CO 2 and H 2 The mixed fluid of O can be connected to the supercritical fluid chromatograph 19 through the fidelity sampler 18 for real-time analysis, and the free CO in the lower liquid phase of the alloy reactor chamber 11 2 That is, CO2 that is dissolved in water 2 , including its relationship with H 2 O reacts to generate H 2 CO 3 , while H 2 CO 3 Depending on the pH of the solution, it will ionize into CO 3 2- or HCO 3 - , CO 3 2- and HCO 3 - Directly participate in the corrosion electrochemical cathode reaction, so it can be measured in real time by CO 3 2- or HCO3 - Concentration improves the accuracy of corrosion simulation and serves as an important acquisition parameter for corrosion mechanism studies.

[0048] The experimental device for metal column corrosion of the present invention introduces a supercritical fluid chromatography analysis unit, collects synchronously through a fidelity sampler 18, and connects to a supercritical fluid chromatography analysis 19 to prepare to measure CO in the alloy reactor chamber 11. 2 Water content and CO 2 The fluid density value is adjusted according to the data feedback value change to adjust the environment in the alloy kettle chamber 11. The PC control device 20 is an existing computer control device, which will not be introduced in detail here. The PC control device 20 controls the supercritical fluid chromatography analysis 19 and the high temperature and high pressure corrosion experimental device unit (temperature and liquid level control device 8, heating temperature control device 9, stirrer 10, pressure sensor 17, potential indicating electrode 23 and automatic titration device 24). The PC in the PC control device 20 is controlled by software: ① Control the temperature, pressure, speed and other parameters of the high temperature and high pressure corrosion experimental device. The temperature and liquid level control device and pressure sensor 17 connected to the alloy kettle chamber 11 transmit the temperature and pressure electrical signals to the PC end, and the PC responds and controls the temperature and pressure to make CO 2 ① Reach the preset phase state; ② Record the results of fluid chromatography analysis; Realize the automated control of the experimental device to improve the experimental accuracy and work efficiency.

[0049] The experimental device for metal column material corrosion of the present invention can also be used to evaluate the slow-release agent, especially for the evaluation of corrosion inhibitors in gas and liquid phases. The specific operation method is: the corrosion inhibitor is added to the lower water phase in the liquid replenishment tank 2 and the alloy kettle chamber 11 respectively, and the upper corrosion inhibitor is dissolved in the supercritical CO 2 / H 2 In the mixed phase of O, the lower corrosion inhibitor is dissolved in the formation water, and the upper and lower metal test pieces are used to evaluate the corrosion inhibition effect respectively. The operation is simple, the experimental effect is good, and the accuracy is high.

[0050] In the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "inside", it is based on the orientation or positional relationship shown in the drawings, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present invention.

[0051] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. An experimental device suitable for metal pipe column material corrosion, characterized by: It comprises an N2 gas source (1), a liquid replenishment unit, a CO2 gas circuit unit, a mixing device (7), a high temperature and high pressure corrosion experiment device unit, a supercritical fluid chromatography analysis unit and an automatic potentiometric titration unit, wherein the outlet of the liquid replenishment unit and the outlet of the CO2 gas circuit unit are both connected to the inlet of the mixing device (7), the outlet of the mixing device (7) and the outlet of the N2 gas source (1) are both connected to the inlet of the high temperature and high pressure corrosion experiment device unit, the gas outlet of the high temperature and high pressure corrosion experiment device unit is connected to the supercritical fluid chromatography analysis unit, and the liquid outlet of the high temperature and high pressure corrosion experiment device unit is connected to the automatic potentiometric titration unit; The high temperature and high pressure corrosion experimental device unit comprises a temperature and liquid level control device (8), a heating temperature control device (9), a stirrer (10), an alloy kettle chamber (11), a multi-layer hanging piece corrosion fixture (12), a gas phase environment corrosion hanging piece (13), a liquid phase environment corrosion hanging piece (14), a bottom probe tube (15) and a pressure sensor (17). The sensing ends of the temperature and liquid level control device (8) and the pressure sensor (17) are both connected to the inside of the alloy kettle chamber (11). The side of the alloy kettle chamber (11) is connected to the heating temperature control device (9). The front of the alloy kettle chamber (11) is provided with an observation window (16). The stirring shaft of the stirrer (10) penetrates into the inside of the alloy kettle chamber (11) and is connected to the multi-layer hanging piece corrosion fixture (12). The multi-layer hanging piece corrosion fixture (12) ) is connected to a gas phase environment corrosion hanging piece (13), and the gas phase environment corrosion hanging piece (13) is located in the gas phase layer in the alloy kettle chamber (11); the lower layer of the multi-layer hanging piece corrosion fixture (12) is connected to a liquid phase environment corrosion hanging piece (14), and the liquid phase environment corrosion hanging piece (14) is located in the liquid phase layer in the alloy kettle chamber (11); the outlets of the N2 gas source (1) and the mixing device (7) are merged through a pipeline and then divided into two paths to communicate with the interior of the alloy kettle chamber (11), wherein the lower end of one pipeline is located in the gas phase layer in the alloy kettle chamber (11), and the other pipeline is connected to a bottom probe tube (15), and the lower end of the bottom probe tube (15) is located in the liquid phase layer in the alloy kettle chamber (11); a liquid discharge port is provided at the bottom of the alloy kettle chamber (11); and scale lines are provided outside the observation window (16); The supercritical fluid chromatography analysis unit comprises a fidelity sampler (18), a supercritical fluid chromatography analyzer (19) and a PC control device (20); the outlet of the alloy kettle chamber (11) is connected to the supercritical fluid chromatography analyzer (19) via the fidelity sampler (18); and the PC control device (20) is electrically connected to the alloy kettle chamber (11) and the supercritical fluid chromatography analyzer (19) respectively; The automatic potentiometric titration unit comprises a liquid storage tank (21), a titration cell (22), a potential indicating electrode (23) and an automatic titration device (24); a liquid discharge port of the alloy kettle chamber (11) is connected to the titration cell (22) via the liquid storage tank (21); one end of the potential indicating electrode (23) and one end of the automatic titration device (24) are both connected to a liquid phase layer in the titration cell (22); and the other end of the potential indicating electrode (23) and the other end of the automatic titration device (24) are both electrically connected to a PC control device (20).

2. The experimental device for metal pipe column corrosion as claimed in claim 1, characterized in that: The N2 gas source (1) is high-purity N2 with a purity of 99.99%.

3. The experimental device for metal pipe column corrosion as claimed in claim 1, characterized in that: The liquid replenishment unit comprises a liquid replenishment tank (2) and an injection pump (3), and the liquid replenishment tank (2) is connected to the inlet of the mixing device (7) via the injection pump (3).

4. The experimental device for metal pipe column corrosion as claimed in claim 3, characterized in that: A mixed liquid of crude oil and water is added to the liquid replenishing tank (2).

5. The experimental device for metal pipe column corrosion as claimed in claim 1, characterized in that: The CO2 gas circuit unit comprises a CO2 gas source (4), a temperature control device (5) and a constant flow metering plunger pump (6), and the inlets of the CO2 gas source (4), the temperature control device (5), the constant flow metering plunger pump (6) and the mixing device (7) are connected in sequence.

6. The experimental device for metal pipe column corrosion as claimed in claim 5, characterized in that: The CO2 gas source (4) is 99.99% high-purity CO2.

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