Method for preventing corrosion of oil well in CO2 flooding bottom water sandstone reservoir and inhibitor injection device

Abstract

The application discloses a CO2 flooding bottom water sandstone reservoir oil well corrosion prevention method and an inhibitor injection device, and relates to the field of oil well corrosion prevention. The application discloses a CO2 flooding bottom water sandstone reservoir oil well corrosion prevention method and an inhibitor injection device, and relates to the field of oil well corrosion prevention. The application discloses a CO2 flooding bottom water sandstone reservoir oil well corrosion prevention method and an inhibitor injection device, and relates to the field of oil well corrosion prevention. The application discloses a CO2 flooding bottom water sandstone reservoir oil well corrosion prevention method and an inhibitor injection device, and relates to the field of oil well corrosion prevention. The application discloses a CO2 flooding bottom water sandstone reservoir oil well corrosion prevention method and an inhibitor injection device, and relates to the field of oil well corrosion prevention. The application discloses a CO2 flooding bottom water sandstone reservoir oil well corrosion prevention method and an inhibitor injection device, and relates to the field of oil well corrosion prevention.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil exploitation, and particularly relates to a method for preventing corrosion of oil wells in CO2 flooding bottom water sandstone reservoirs and a slow-release agent injection device. BACKGROUND

[0002] The part provided in this section is merely background information related to the present application, which does not necessarily have to be prior art.

[0003] The bottom water sandstone reservoir belongs to a faulted anticline, medium-porosity, medium-high permeability sandstone reservoir, and the bottom water energy is large, mainly developed by horizontal wells. The bottom water sandstone reservoirs are widely distributed at home and abroad, and most of the reservoirs are currently in a high water cut development stage, with serious water flooding of oil wells, and most of the bottom water sandstone reservoirs lack effective treatment means and are stopped or abandoned. Recently, the CO2 flooding pilot test of the bottom water sandstone reservoir has been successful, and the test proves that the CO2 flooding technology has good effect on the exploitation of the bottom water sandstone reservoir. However, the bottom water sandstone reservoir often has many complex factors such as high water cut (the comprehensive water cut of some well groups is as high as 93%), high salt (the salinity of some well groups is 20-21×104mg / L, Cl - content 6.8-12×104mg / L), high temperature (97-110℃), and low pH value (pH 5.8-6.1), and therefore, the method for preventing corrosion of oil wells in CO2 flooding bottom water sandstone reservoirs becomes the key to the smooth exploitation of such reservoirs.

[0004] In the actual research of oil well corrosion prevention, the CO2 corrosion rules and mechanisms under different temperatures, different media, and different ion contents are different, and the corrosion mechanism is quite complex. Even for the same position of the same oil well, the corrosion conditions will change greatly with time. The bottom water sandstone reservoir with high temperature, high salt, and low pH value has a very special corrosion environment, and no relevant corrosion mechanism research has been carried out under this environment, which brings great difficulties to the oil well corrosion prevention of CO2 flooding bottom water sandstone reservoirs and great challenges to the exploitation of CO2 flooding bottom water sandstone reservoirs.

[0005] At present, there is no suitable corrosion prevention method for the oil wells of CO2 flooding bottom water sandstone reservoirs. In order to solve the corrosion problem, the amount of corrosion inhibitor has to be increased to achieve the effect of oil well corrosion prevention, which greatly increases the cost of oil well corrosion prevention of CO2 flooding bottom water sandstone reservoirs, and further increases the exploitation cost of such reservoirs. SUMMARY

[0006] The present application proposes a method for preventing corrosion of oil wells in CO2 flooding bottom water sandstone reservoirs and a slow-release agent injection device, aiming to solve the problem of corrosion prevention of oil wells in CO2 flooding bottom water sandstone reservoirs and provide technical support for the exploitation of such reservoirs. The purpose is achieved by the following technical solutions:

[0007] The first aspect of the present application provides a corrosion prevention method for oil wells of CO2 flooding bottom water sandstone reservoirs, comprising the following steps:

[0008] S1: determining the metal material used in the oil wells of the CO2 flooding bottom water sandstone reservoirs that needs to be prevented from corrosion;

[0009] S2: preparing a metal sample according to the metal material determined in S1, simulating the working condition of the CO2 flooding bottom water sandstone reservoir to conduct corrosion test, and determining the corrosion factors of the metal sample in the oil wells of the CO2 flooding bottom water sandstone reservoir;

[0010] S3: determining the corrosion resistance of the metal material used in the oil wells under different corrosion conditions according to the corrosion factors determined in S2;

[0011] S4: selecting the corrosion inhibitor according to the corrosion resistance of the metal material used in the oil wells under different corrosion conditions, and loading the selected corrosion inhibitor into the corrosion inhibitor injection device;

[0012] S5: determining the concentration of the corrosion inhibitor required in the produced liquid of the current set time period in combination with the corrosion resistance of the metal material under different corrosion conditions and the corrosion condition of the produced liquid of the current set time period;

[0013] S6: determining and adjusting the injection amount and injection speed of the corrosion inhibitor of the corrosion inhibitor injection device in the adjacent next set time period according to the concentration of the corrosion inhibitor required in the produced liquid of the current set time period determined in S5, so that the corrosion rate of the oil well is less than 0.076 mm / a (millimeter per year).

[0014] The present application determines the metal material used in the oil wells of the CO2 flooding bottom water sandstone reservoirs that needs to be prevented from corrosion, uses the corresponding metal material as a sample to simulate the working condition of the CO2 flooding bottom water sandstone reservoir to conduct corrosion test, further determines the corrosion factors of the oil wells of the CO2 flooding bottom water sandstone reservoir, and thus solves the corrosion problem of the oil wells of the CO2 flooding bottom water sandstone reservoir. The corrosion prevention method developed accordingly can more scientifically solve the corrosion problem of the oil wells of such reservoirs, and can provide technical support for the exploitation of a large number of such reservoirs that have been stopped and abandoned.

[0015] In addition, the present application determines the concentration of the corrosion inhibitor required in the oil wells of the CO2 flooding bottom water sandstone reservoir by studying the corrosion of the oil wells of the CO2 flooding bottom water sandstone reservoir and analyzing the corrosion condition of the produced liquid, further determines the injection amount and injection speed of the corrosion inhibitor in the adjacent next set time period according to the way of adding the corrosion inhibitor, and controls the corrosion inhibitor injection device, thereby avoiding the problems such as high exploitation cost caused by the blind corrosion prevention method of increasing the corrosion inhibitor.

[0016] As some preferred embodiments of the present application, the corrosion factors determined in step S2 are further selectively selected to include temperature, CO2 partial pressure, flow rate, and crude oil water cut; and the metal sample is at least one of a sample made of P110S steel, a sample made of P110-13Cr steel, a sample made of P110 steel, and a sample made of N80 steel.

[0017] As some preferred embodiments of the present application, in step S2, the temperature is further selectively selected to be in the range of 35-120°C; and / or the CO2 partial pressure is further selectively selected to be in the range of 0.5-2.0 MPa; and / or the flow rate is further selectively selected to be in the range of 0.5-2.0 m / s; and / or the crude oil water cut is further selectively selected to be in the range of 20-95%.

[0018] As some preferred embodiments of the present application, step S3 further selectively includes:

[0019] S31: uniformly mixing crude oil and water in a set proportion to form an oil-water mixture, and loading the oil-water mixture and a metal sample into a reaction vessel;

[0020] S32: adjusting the temperature in the reaction vessel to a set temperature, and adjusting the pressure in the reaction vessel to a set pressure;

[0021] S33: adjusting the flow rate of the oil-water mixture in the reaction vessel according to a set flow rate;

[0022] S34: allowing the weighed metal sample to react at the set temperature, the set pressure, and the set flow rate for a set period of time;

[0023] S35: removing the reacted metal sample, and cleaning, drying, and weighing the metal sample;

[0024] S36: determining the corrosion rate of the metal sample according to the mass difference of the metal sample before and after reaction.

[0025] The present application can more realistically simulate the corrosion environment of CO2 flooding bottom water sandstone reservoirs by supplying CO2 into the oil-water mixture before adjusting the temperature and pressure in the reaction vessel, thereby avoiding the influence of oxygen on the test results, making the research results more objective and scientific. In addition, the test results without supplying CO2 into the oil-water mixture can be compared, thereby reflecting the corrosion degree of CO2 on oil wells, and providing guidance or reference for the corrosion prevention work of CO2 flooding oil wells.

[0026] As some preferred embodiments of the present application, in step S5, the concentration of the corrosion inhibitor required in the produced fluid in the set time period is calculated according to the following formula:

[0027]

[0028] C is the concentration of the corrosion inhibitor required in the produced liquid;

[0029] β is a correction coefficient;

[0030] V is the corrosion rate of the produced liquid of the current set time period to the oil well;

[0031] a is the percentage content of carbon dioxide in the produced liquid of the current set time period;

[0032] η is the water cut in the produced liquid of the current set time period;

[0033] C0 is the concentration of the corrosion inhibitor required by the oil well when the corrosion rate reaches 0.076 mm / a.

[0034] The application can estimate the concentration of the corrosion inhibitor required in the produced liquid of the current set time period by the above formula, and then estimate the injection amount and injection speed of the corrosion inhibitor of the adjacent next set time period according to the value. Based on the formula, the corrosion inhibitor injection device can correct the injection amount and injection speed of the corrosion inhibitor according to the actual analysis of the produced liquid. It is found through verification that, compared with the traditional corrosion inhibitor injection method, the estimation of the injection amount and injection speed by the above calculation formula can achieve better corrosion prevention effect while using less corrosion inhibitor, thereby effectively reducing the corrosion prevention cost of the oil well and having great popularization significance. In addition, in specific implementation, the above formula can be used as an algorithm for controlling the corrosion inhibitor injection device, thereby providing a basis for realizing the automatic control of the corrosion inhibitor injection device.

[0035] It should be noted that the correction coefficient β is a correction value set based on the complex corrosion factors of the CO2 flooding bottom water sandstone reservoir, which is obtained through experimental analysis of the corrosion factors, including temperature, salt type, salt content, material selection of the oil well, and flow rate. The corrected calculation formula makes the corrosion prevention measures for the oil wells of this type of reservoir more reliable and effectively avoids the problem of substandard corrosion of the oil well due to changes in the corrosion environment.

[0036] As some preferred embodiments of the application, the determination of the injection amount of the corrosion inhibitor of the adjacent next set time period in the S6 step further selectively includes the following steps:

[0037] S61: determining the produced liquid amount Q1 of the oil well in the current set time period;

[0038] S62: determining the water cut f in the produced liquid amount Q1 of the current set time period;

[0039] S63: determining the concentration C1 of the corrosion inhibitor injected into the oil well in the next adjacent set time period;

[0040] The injection amount Q of the corrosion inhibitor in the next adjacent set time period is determined according to the following formula:

[0041]

[0042] The application can determine the injection amount of the corrosion inhibitor in the next adjacent set time period through the calculation formula. It is verified that, compared with the traditional setting method of the injection amount, the injection amount of the corrosion inhibitor determined by the technical method has the advantages of more saving of the corrosion inhibitor and the like while meeting the corrosion prevention requirements. Moreover, the control of the corrosion inhibitor injection device is provided, and many problems (such as increasing labor cost, not timely adjustment and the like) caused by manual field sampling are avoided.

[0043] As some preferred embodiments of the application, the corrosion inhibitor is selectively injected into the oil well in a continuous injection manner in the step S6, and the calculation formula of the injection speed v of the corrosion inhibitor in the next adjacent set time period is:

[0044]

[0045] Wherein: t is the time length of the next adjacent set time period;

[0046] Q is the injection amount of the corrosion inhibitor in the next adjacent set time period;

[0047] v is the injection speed of the corrosion inhibitor in the next adjacent set time period.

[0048] The application injects the corrosion inhibitor in a continuous injection manner, and the injection speed of the corrosion inhibitor in the set time period can be calculated through the calculation formula. It is verified that the injection amount of the corrosion inhibitor determined by the technical method has the advantages of more saving of the corrosion inhibitor and the like while meeting the corrosion prevention requirements.

[0049] As some preferred embodiments of the application, the step S4 is further selectively included as follows when the corrosion inhibitor is selected:

[0050] S41: selecting a plurality of corrosion inhibitors, and performing water solubility experiment on each corrosion inhibitor to determine whether the corrosion inhibitor has emulsification tendency;

[0051] S42: selecting the corrosion inhibitor without emulsification tendency, and testing the slow-release rate of the corrosion inhibitor under the set condition;

[0052] S43: screening out the corrosion inhibitor with the slow-release rate greater than the set value to evaluate the corrosion rate under the simulated working condition; when the corrosion rate of the metal sample is less than 0.076 mm / a, the slow-release inhibitor is qualified; when the corrosion rate of the metal sample is greater than or equal to 0.076 mm / a, the corrosion inhibitor is unqualified.

[0053] As some preferred embodiments of the present application, the current set time period is further selectively set to any value in 1 hour to 72 hours, and the next set time period is set to any value in 1 hour to 72 hours. By setting the time period to any value between 1 hour and 72 hours, the present application can effectively adjust the implementation of the corrosion prevention process. Avoid adjusting the time too long, which can cause problems caused by changes in the corrosion environment, and can also avoid adjusting the time too short.

[0054] In a second aspect, the present application discloses a corrosion inhibitor injection device for implementing the oil well corrosion prevention method of the CO2 flooding bottom water sandstone reservoir.

[0055] The corrosion inhibitor storage unit is used for storing the corrosion inhibitor;

[0056] The corrosion inhibitor variable pumping unit is used for connecting the corrosion inhibitor storage unit with the annular space between the production pipe and the wellbore;

[0057] The information acquisition module includes a carbon dioxide content detection unit, a water cut detection unit and a corrosion rate detection unit, the carbon dioxide content detection unit is used for detecting the content of carbon dioxide in the produced fluid, the water cut detection unit is used for detecting the water cut in the produced fluid, and the corrosion rate detection unit is used for detecting the corrosion rate of the produced fluid to the oil well;

[0058] The control unit is signal connected with the carbon dioxide content detection unit, the water cut detection unit and the corrosion rate detection unit; and the corrosion inhibitor variable pumping unit is signal connected with the control unit.

[0059] The information processing module is used for processing the information collected by the information acquisition module; the information processing module is signal connected with the control unit and the information acquisition module.

[0060] The above description is only a summary of the technical solutions of the embodiments of the present application, in order to more clearly understand the technical means of the embodiments of the present application, the embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the embodiments of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 The flowchart of the oil well corrosion prevention method mentioned in the present application;

[0062] Figure 2 A structural schematic diagram of an inhibitor injection device is schematically shown.

[0063] Figure 3 A schematic diagram of a monitoring unit of the inhibitor injection device involved in the present application.

[0064] The reference signs are as follows:

[0065] 1 inhibitor variable pumping unit;

[0066] 2 information acquisition module;

[0067] 3 control unit;

[0068] 4 information processing module;

[0069] 5 early warning unit;

[0070] 6 information storage module;

[0071] 7 information remote transmission module;

[0072] 81 liquid storage tank, 82 heating assembly, 83 liquid level meter;

[0073] 91 production pipe, 92 wellbore, 93 annular space. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative work under the premise that the embodiments in the present application are within the scope of protection of the present application.

[0075] Unless otherwise defined, all technical and scientific terms used in the present application have the same meanings as those commonly understood by those skilled in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments of the present application, and are not intended to limit the present application; the terms “include” and “have” and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms “first”, “second” and the like in the specification and claims of the present application or the above description of drawings are used to distinguish different objects, and are not intended to describe a particular order or primary and secondary relationship.

[0076] Reference to an "implementation" in this application means that a particular feature, structure, or characteristic described in connection with an implementation can be included in at least one implementation of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same implementation, nor is it necessarily referring to a separate or alternative implementation to the other implementations.

[0077] In the description of the application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0078] The term "and / or" in this application is only to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the front and rear associated objects.

[0079] In a first aspect, the application provides a method for preventing corrosion of oil wells in CO2 flooding bottom water sandstone reservoirs, as shown in the following steps: Figure 1 S1: determining the metal material used in the oil well of the CO2 flooding bottom water sandstone reservoir which needs to be prevented from corrosion; S2: preparing a metal sample according to the metal material determined in S1, simulating the working condition of the CO2 flooding bottom water sandstone reservoir to conduct corrosion test, and determining the corrosion factors of the metal sample in the oil well of the CO2 flooding bottom water sandstone reservoir; S3: determining the corrosion resistance of the metal material used in the oil well under different corrosion conditions according to the corrosion factors determined in S2; S4: selecting a corrosion inhibitor according to the corrosion resistance of the metal material used in the oil well under different corrosion conditions, and loading the selected corrosion inhibitor into a corrosion inhibitor injection device; S5: determining the concentration of the corrosion inhibitor required in the produced liquid of the current setting period in combination with the corrosion resistance of the metal material under different corrosion conditions and the corrosion condition of the produced liquid of the current setting period; S6: determining and adjusting the injection amount and injection speed of the corrosion inhibitor of the corrosion inhibitor injection device in the adjacent next setting period according to the concentration of the corrosion inhibitor required in the produced liquid of the current setting period determined in S5, so that the corrosion rate of the oil well is less than 0.076 mm / a (millimeter per year).

[0080] It should be noted that there is no necessary sequence between S1, S2, S3, S4, S5 and S6, which are only symbols representing each step; for example, S1 is a symbol representing the step of "determining the metal material that needs to be protected from corrosion for the oil well of the CO2 flooding bottom water sandstone reservoir"; similarly, S2, S3, S4, S5 and S6 are only symbols representing each corresponding step. This writing method is only for convenience of description.

[0081] It should be noted that in this application, the so-called "metal material that needs to be protected from corrosion for the oil well" refers to the material that exists in the corrosion condition during the use of the oil well of the CO2 flooding bottom water sandstone reservoir; for example, the metal material used in the wellbore, oil pipe, sucker rod, etc.; the corrosion protection process is mainly for the inner surface of the wellbore, the inner and outer surfaces of the oil pipe, and the outer surface of the sucker rod, etc. It should be pointed out that the metal material that needs to be protected from corrosion can be one or more, for example, one, two, three, four, five or more than six, and it should be noted that more than a certain number includes the number, for example, more than six includes six.

[0082] It should be noted that in this application, the so-called "simulating the working condition of the CO2 flooding bottom water sandstone reservoir" refers to simulating the environment condition in which the structure, component or assembly that needs to be protected from corrosion is located during the actual use of the oil well of the CO2 flooding bottom water sandstone reservoir. The working condition environment is not limited specifically, which is determined according to the specific situation of the studied oil well.

[0083] It should be noted that in this application, the so-called "concentration of the corrosion inhibitor required to be reached in the produced liquid of the current set time period" refers to the concentration of the corrosion inhibitor required to be reached when the corrosion rate of the produced liquid of the current set time period to the oil well is less than 0.076 mm / a.

[0084] It should be noted that in this application, the so-called "corrosion condition of the produced liquid of the current set time period" refers to the corrosion factor that causes corrosion to the material that needs to be protected from corrosion used in the oil well of the current set time period, for example, the water content and CO2 content in the produced liquid.

[0085] In specific implementation, step S3 can be optionally selected to include the following process: screening the corrosion factors that cause corrosion in the CO2 flooding bottom water sandstone reservoir, and taking the corrosion factors as test variables; determining several metal samples that need to be protected from corrosion used in the oil well of the bottom water sandstone reservoir; adjusting the parameters of the test variables to form different test conditions, and grouping the corrosion rates of the metal samples for testing; determining the corrosion rate of each metal sample under different set conditions according to the test results, and determining the corrosion resistance of the metal sample under different test conditions through comparison of the corrosion rates; and determining the corrosion protection measures for the oil well of the CO2 flooding bottom water sandstone reservoir according to the corrosion resistance of the metal sample.

[0086] It should be noted that the so-called "corrosion factors" refer to factors that can cause corrosion to the oil well, and can selectively include temperature, CO2 partial pressure, flow rate and crude oil water cut, but are not limited to including temperature, CO2 partial pressure, flow rate and crude oil water cut. It can also include other factors that can cause corrosion to the oil well, such as the type of salt, the proportion of salt, etc.

[0087] It should be noted that the structure of the metal sample is not specifically limited, and in specific implementation, the metal sample is preferably provided in a sheet structure with the same surface area, which can also be referred to as a metal test piece; in order to avoid confusion, the metal sample tested is preferably marked in specific implementation.

[0088] It should be noted that the so-called "adjusting the parameters of the test variables" refers to adjusting parameters including temperature, CO2 partial pressure, flow rate and crude oil water cut. In addition, it should be noted that the so-called "corrosion resistance" refers to the ability of the metal sample to resist corrosion.

[0089] In specific implementation, the corrosion reaction test can be selectively performed in a reaction kettle.

[0090] The present application can determine the corrosion resistance of metal samples of different materials under different test conditions by screening the corrosion factors that cause corrosion in bottom water sandstone reservoirs and testing the corrosion rates of metal materials used in oil wells of CO2 flooding bottom water sandstone reservoirs in different environments. Based on the test results, the corrosion prevention process for CO2 flooding bottom water sandstone reservoirs is further determined, and the corrosion prevention process determined accordingly can effectively prevent corrosion of the oil well and achieve better corrosion prevention effect. In addition, according to the test results, the selection and arrangement of materials for CO2 flooding bottom water sandstone reservoirs can be guided, such as arranging wellbores, oil pipes, etc. of different materials according to the corrosion conditions at different positions in the well depth direction. The oil well constructed accordingly has better corrosion resistance and can effectively reduce the corrosion prevention cost of the oil well. In addition, during the construction of the oil well, the materials of the wellbore, oil pipe, etc. can be selected according to the different corrosion environments at different positions of the oil well, thereby reducing the construction cost of the oil well.

[0091] In specific implementation, the corrosion rate of the metal sample is further selectively determined according to the mass difference of the metal sample before and after the reaction, and the calculation formula of the corrosion rate is:

[0092]

[0093] V = (m1-m2) / t corr The corrosion rate is mm / a;

[0094] Δm is the weight loss of the metal sample, Δm = m0-m1, m0 is the weight of the metal sample before corrosion test, m1 is the weight of the metal sample after corrosion test, and the unit is g;

[0095] ρ is the density of the metal sample, and the unit is g / cm 3 ;

[0096] t is the reaction time, and the unit is h;

[0097] S is the surface area of the metal sample, and the unit is cm 2 .

[0098] The application can more accurately calculate the corrosion rate of the metal sample through the mass of the metal sample before the test and the mass of the metal sample after the test by the above corrosion rate calculation formula.

[0099] The application determines the metal material required for corrosion prevention used in the oil well of the CO2 flooding bottom water sandstone reservoir, and uses the corresponding metal material as a sample to simulate the working condition environment of the CO2 flooding bottom water sandstone reservoir for corrosion test, further determines the corrosion factors of the oil well of the CO2 flooding bottom water sandstone reservoir, and determines the corrosion prevention basis of the oil well of the CO2 flooding bottom water sandstone reservoir, thereby solving the corrosion prevention problem of the oil well of the CO2 flooding bottom water sandstone reservoir, and the corrosion prevention method formulated accordingly can more scientifically and specifically solve the corrosion prevention problem of the oil well of the CO2 flooding bottom water sandstone reservoir, and can provide technical support for the exploitation of a large number of such oil reservoirs that have stopped and abandoned.

[0100] In addition, the application determines the inhibitor concentration required for the oil well of the CO2 flooding bottom water sandstone reservoir through corrosion research on the oil well of the CO2 flooding bottom water sandstone reservoir and analysis of the corrosion conditions of the produced liquid, and further determines the injection amount and injection speed of the inhibitor in the next set time period according to the way of adding the inhibitor, thereby controlling the inhibitor injection device and avoiding the problem of high exploitation cost caused by the blind increase of the corrosion prevention method of the inhibitor.

[0101] As some preferred embodiments of the application, the corrosion factors determined in the S2 step are further selectively selected to include temperature, CO2 partial pressure, flow rate, and water content of crude oil; and the metal sample is at least one of a sample made of P110S steel material, a sample made of P110-13Cr steel material, a sample made of P110 steel material, and a sample made of N80 steel material.

[0102] Based on previous experiments and a large amount of research work, the present application selects temperature, CO2 partial pressure, flow rate and water content of crude oil as the main test variables of the oil well of the CO2 flooding bottom water sandstone reservoir, different test conditions are formed by adjusting the test variables, and the corrosion environment of the oil well of the bottom water sandstone reservoir can be better restored. The test results based on this can more objectively reflect the corrosion environment of the CO2 flooding bottom water sandstone reservoir, and the results obtained by the test provide more objective and effective guidance for the development of the corrosion prevention process of the CO2 flooding bottom water sandstone reservoir. Specifically, according to the analysis of these corrosion factors and the guidance of the development of the corrosion prevention process of the oil well of this type of reservoir, the corrosion prevention can meet the corrosion prevention requirements, while the waste of the corrosion inhibitor can be avoided, and the mining cost of this type of reservoir can be reduced.

[0103] It should be noted that the bottom water sandstone reservoir often uses metal products with P110-13Cr steel material, P110S steel material, P110 steel material and N80 steel material (for example, the wellbore is often made of P110-13Cr steel material, P110S steel material, P110 steel material and N80 steel material), because the materials are different, the metal products also have a big difference in price, so it is very important to study the corrosion reasons of the CO2 flooding bottom water sandstone reservoir for the development and corrosion prevention of this type of reservoir.

[0104] The present application makes the metal sample include the sample with P110S steel material, the sample with P110-13Cr steel material, the sample with P110 steel material and the sample with N80 steel material, by taking the commonly used material of the oil well as the main research object, the corrosion rate of each material under different environments and conditions can be studied according to the specific corrosion environment of the CO2 flooding bottom water sandstone reservoir, and a more scientific basis for the corrosion prevention process and strategy of the CO2 flooding bottom water sandstone reservoir can be provided according to the corrosion resistance of each metal material in different corrosion environments. In addition, in the depth direction of the oil well, the corrosion conditions are different, and the corrosion resistance of the sample with P110S steel material, the sample with P110-13Cr steel material, the sample with P110 steel material and the sample with N80 steel material is also different under different corrosion conditions, and there is no rule to follow. The test results obtained by taking the above materials as test objects provide scientific reference and basis for the material selection of the oil well, for example, different materials can be selected for the wellbore, tubing and the like at different depths of the same oil well according to the different corrosion resistance of different materials under different corrosion conditions.

[0105] As some preferred embodiments of the present application, further selectively in step S2, the temperature is selected in the range of 35-120℃; and / or, the CO2 partial pressure is selected in the range of 0.5-2.0 MPa; and / or, the flow rate is selected in the range of 0.5-2.0 m / s; and / or, the water content of the crude oil is selected in the range of 20%-95%.

[0106] By selecting the temperature, CO2 partial pressure, flow rate, and water content of the crude oil in the above numerical ranges, the present application can cover the corrosion environment of CO2 flooding bottom water sandstone reservoirs in different geographical locations, making the research of the corrosion environment more sufficient, and providing more comprehensive guidance for the corrosion prevention method of such reservoirs. Specifically, by selecting the temperature, CO2 partial pressure, flow rate, and water content of the crude oil in the above ranges, the selected numerical range can cover the corrosion environment at different depths of the bottom water sandstone reservoir. Based on this, different positions of the bottom water sandstone reservoir can be tested, and further according to the research results, the material of the wellbore, tubing, etc. can be selected in combination with the material cost, corrosion difficulty, corrosion cost, etc., and the wellbore can be arranged in the well depth direction according to the corrosion rate at different positions. Specifically, different materials of the wellbore can be selected according to the different positions of the well depth to achieve the effect of reducing the cost and the corrosion cost in the oil production process. In specific implementation, the test selected value of the temperature can further be selected to include 35℃, 60℃, 90℃, and 120℃; and / or, the test selected value of the CO2 partial pressure can further be selected to include 0.5 MPa, 1 MPa, 1.5 MPa, and 2 MPa; and / or, the test selected value of the flow rate can further be selected to include 0.5 m / s, 1 m / s, 1.5 m / s, and 2 m / s; and / or, the test selected value of the water content of the crude oil can further be selected to include 20%, 50%, 80%, and 95%.

[0107] As some preferred embodiments of the present application, step S3 further selectively includes:

[0108] S31: uniformly mixing the crude oil and water according to a set proportion to form an oil-water mixture, and loading the oil-water mixture and a metal sample into a reaction container;

[0109] S32: adjusting the temperature in the reaction container to a set temperature, and adjusting the pressure in the reaction container to a set pressure;

[0110] S33: adjusting the flow rate of the oil-water mixture in the reaction container according to a set flow rate;

[0111] S34: making the weighed metal sample react for a set time at the set temperature, the set pressure, and the set flow rate;

[0112] S35: taking out the reacted metal sample, and cleaning, drying, and weighing the metal sample;

[0113] S36: determining the corrosion rate of the metal sample according to the mass difference of the metal sample before and after the reaction.

[0114] It should be noted that the "set ratio" in S31 is set according to the test requirements. For example, the crude oil accounts for 20%, and the water accounts for 80%, or the crude oil accounts for 30%, and the water accounts for 70%, etc. In specific implementation, the selective setting is performed according to the setting of the test conditions. In specific implementation, preferably, the test water is taken from the formation of the studied bottom water sandstone reservoir, and the crude oil is taken from the formation of the studied bottom water sandstone reservoir; in this way, the corrosion conditions of the studied bottom water sandstone reservoir can be more accurately and objectively simulated. Similarly, in S34, the set temperature, the set pressure, the set flow rate, and the set time length are also selectively set according to the setting of the test conditions. In specific implementation, preferably, the crude oil is collected from the reservoir that needs to be prevented from corrosion, and further preferably, the water is also collected from the reservoir that needs to be prevented from corrosion.

[0115] It should be noted that when step S32 is performed, the temperature can be adjusted first, and then the pressure is adjusted; or the pressure is adjusted first, and then the temperature is adjusted.

[0116] The present application can more accurately reflect the corrosion conditions of different corrosion environments by mixing the crude oil and the water in a set ratio, further adjusting the conditions of the temperature, the pressure, and the flow rate according to the actual corrosion environment of the wellbore, and then making the research conclusion more meaningful.

[0117] As some preferred embodiments of the present application, further selectively in S34, the set reaction time length of the metal sample in the reaction container is greater than or equal to 72 hours. In specific implementation, the reaction time length can be selectively set to 72 hours, 96 hours, 120 hours, 144 hours, 168 hours, 192 hours, 216 hours, or 240 hours; etc. Here, no specific limitation is made, and in specific implementation, the set reaction time length of the metal sample in the reaction container is not limited to the above-mentioned time lengths, and it can be any reaction time length greater than 72 hours.

[0118] As some preferred embodiments of the present application, further selectively, between S31 and S32, CO2 is supplied into the oil-water mixture to remove oxygen in the oil-water mixture.

[0119] The application can simulate the corrosion environment of CO2 flooding bottom water sandstone reservoir more truly, avoid the influence of oxygen on the test results, make the research results more objective and more referential by supplying CO2 into the oil-water mixture before adjusting the temperature and pressure in the reaction container.

[0120] In the specific implementation, the oil-water mixture is loaded into the reaction kettle, and sufficient CO2 gas is supplied into the oil-water mixture to remove the oxygen in the oil-water mixture.

[0121] As some preferred embodiments of the application, the S31 and S32 further selectively comprise: supplying CO2 into the oil-water mixture to remove the oxygen in the oil-water mixture.

[0122] The application can simulate the corrosion environment of CO2 flooding bottom water sandstone reservoir more truly, avoid the influence of oxygen on the test results, make the research results more objective and more referential by supplying CO2 into the oil-water mixture before adjusting the temperature and pressure in the reaction container.

[0123] As some preferred embodiments of the application, the concentration of the corrosion inhibitor required in the produced liquid in the current setting time period is calculated according to the following formula in the S5 step.

[0124]

[0125] Wherein: C is the concentration of the corrosion inhibitor required in the produced liquid (Kg / m 3 );

[0126] β is a correction coefficient;

[0127] V is the corrosion rate of the produced liquid of the current setting time period to the oil well (mm / a);

[0128] a is the percentage content of carbon dioxide in the produced liquid of the current setting time period (%);

[0129] η is the water content in the produced liquid of the current setting time period (%);

[0130] C0 is the concentration of the corrosion inhibitor required by the oil well when the corrosion rate is 0.076 mm / a (Kg / m 3 ).

[0131] It should be noted that the corrosion rate of the produced liquid to the oil well can be detected by the corrosion rate detection device and the relevant detection information can be obtained; similarly, the percentage content of carbon dioxide in the produced liquid and the water content in the produced liquid can also be detected by the corresponding detection unit respectively.

[0132] The application can estimate the concentration of the corrosion inhibitor required in the produced liquid in the set period of time through the above formula, and then estimate the injection amount and injection speed of the corrosion inhibitor in the adjacent next set period of time according to the value. Based on this formula, the corrosion inhibitor injection device can correct the injection amount and injection speed of the corrosion inhibitor according to the actual analysis of the produced liquid. It is found through verification that, compared with the traditional corrosion inhibitor injection method, the use of the above calculation formula for estimating the injection amount and injection speed can achieve better corrosion prevention effect while using less corrosion inhibitor, thereby effectively reducing the corrosion prevention cost of the oil well and having great popularization significance. In addition, in specific implementation, the above formula can be used as an algorithm for controlling the corrosion inhibitor injection device, thereby providing a basis for realizing the automatic control of the corrosion inhibitor injection device.

[0133] It should be noted that the correction coefficient β is a correction value set based on the complex corrosion factors of CO2 flooding bottom water sandstone reservoir, which can be obtained through experimental analysis of corrosion factors, including temperature, salt type, salt content, oil well material selection and produced liquid flow rate, etc. The corrected calculation formula and the corrosion prevention measures implemented for the oil wells of this type of reservoir are more reliable, effectively avoiding the problem of substandard oil well corrosion due to the deterioration of the corrosion environment. It should be pointed out that the correction coefficient β≥0.

[0134] As some preferred embodiments of the application, the determination of the injection amount of the corrosion inhibitor in the adjacent next set period of time in the S6 step further selectively includes the following steps:

[0135] S61: determining the produced liquid amount Q1(T or m 3 ) of the oil well in the current set period of time;

[0136] S62: determining the water content f(%) in the produced liquid amount Q1 in the current set period of time;

[0137] S63: determining the concentration C1(Kg / m 3 ) of the corrosion inhibitor injected into the oil well in the adjacent next set period of time

[0138] The injection amount Q(T or m 3 ) of the corrosion inhibitor in the adjacent next set period of time is determined according to the following formula:

[0139]

[0140] C = (C0- C1) / t 3 The application can determine the injection amount of the corrosion inhibitor in the next adjacent setting time period through the calculation formula. It is verified that, compared with the traditional setting method of the injection amount, the injection amount of the corrosion inhibitor determined by the technical method has the advantages of saving the corrosion inhibitor and meeting the corrosion prevention requirements. Moreover, the application provides a basis for the control of the corrosion inhibitor injection device, avoiding many problems caused by manual field sampling.

[0141] As some preferred embodiments of the application, the corrosion inhibitor is selectively injected into the oil well in a continuous injection manner in the step S6, and the calculation formula of the injection speed v of the corrosion inhibitor in the next adjacent setting time period is:

[0142]

[0143] Wherein, t is the next adjacent setting time period.

[0144] The application injects the corrosion inhibitor in a continuous injection manner, and calculates the injection speed of the corrosion inhibitor in the setting time period through the calculation formula. It is verified that the injection amount of the corrosion inhibitor determined by the technical method has the advantages of saving the corrosion inhibitor and meeting the corrosion prevention requirements.

[0145] As some preferred embodiments of the application, the step S4 further selectively includes the following steps when the corrosion inhibitor is selected:

[0146] S41: Selecting a plurality of corrosion inhibitors, and performing water solubility experiments on each corrosion inhibitor to determine whether the corrosion inhibitor has an emulsification tendency;

[0147] S42: Selecting the corrosion inhibitor without the emulsification tendency, and testing the release rate of the corrosion inhibitor under the set conditions;

[0148] S43: Screening the corrosion inhibitor with the release rate greater than the set value to evaluate the corrosion rate under the simulated working conditions; when the corrosion rate of the metal sample is less than 0.076 mm / a, the release agent is qualified, and when the corrosion rate of the metal sample is greater than or equal to 0.076 mm / a, the corrosion inhibitor is unqualified.

[0149] As some preferred embodiments of the application, the current setting time period is selectively set to any value in the range of 1 hour to 72 hours, and the next setting time period is selectively set to any value in the range of 1 hour to 72 hours. The application sets the setting time period to any value in the range of 1 hour to 72 hours, so that the implementation of the corrosion prevention process can be adjusted in time. The adjustment time is not too long, and the problem caused by the change of the corrosion environment is avoided.

[0150] It should be noted that the duration of the "current set time period" and the duration of the "adjacent next set time period" in this application are not specifically limited. They can be selectively set according to actual production needs. For example, the "current set time period" and the "adjacent next set time period" can be selectively set to any time period between 1 hour and 72 hours. Specifically, the set time period can be any value from 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, 40 hours, 42 hours, 44 hours, 46 hours, 48 ​​hours, 50 hours, 52 hours, 54 hours, 56 hours, 58 hours, 60 hours, 62 hours, 64 hours, 66 hours, 68 hours, 70 hours, and 72 hours. Of course, in practice, the set time period is not limited to the data listed above; it can be any value between 1 hour and 72 hours, such as 7 hours or 7.5 hours. When setting the time period, it should be selectively set according to the actual situation of the oil well and specifically based on the information provided by the produced fluid. In practice, the duration of the "current set time period" and the "next set time period" can be made the same, or the duration of the "current set time period" and the "next set time period" can be made different.

[0151] Secondly, this application discloses a corrosion inhibitor injection device for implementing the oil well corrosion prevention method for CO2-driven bottom water sandstone reservoirs described in any of the foregoing embodiments, such as... Figure 2 As shown, the corrosion inhibitor injection device includes a corrosion inhibitor storage unit, a corrosion inhibitor variable pumping unit, an information acquisition module, a control unit, and an information processing module. The corrosion inhibitor storage unit is used to store corrosion inhibitors. The corrosion inhibitor storage unit is connected to the annular space 93 between the production tubing 91 and the wellbore 92 via the corrosion inhibitor variable pumping unit 1. The information acquisition module 2 includes a carbon dioxide content detection unit, a water cut detection unit, and a corrosion rate detection unit. The carbon dioxide content detection unit is used to detect the carbon dioxide content in the produced fluid, the water cut detection unit is used to detect the water cut in the produced fluid, and the corrosion rate detection unit is used to detect the rate of corrosion of the oil well by the produced fluid. The control unit 3 is signal-connected to the carbon dioxide content detection unit, the water cut detection unit, and the corrosion rate detection unit. The corrosion inhibitor variable pumping unit 1 is signal-connected to the control unit 3. The information processing module 4 is used to process the information acquired by the information acquisition module. The information processing module 4 is signal-connected to the control unit 3 and the information acquisition module 2.

[0152] It should be noted that the structure of the corrosion inhibitor storage unit in the present application is not specifically limited, which can be any structure capable of storing corrosion inhibitors, for example, the corrosion inhibitor storage unit is provided as a tank or a box. Similarly, the type of the corrosion inhibitor variable pumping unit 1 is not specifically limited, which can be any variable pump capable of pumping corrosion inhibitors and adjusting the pumping flow; in specific implementation, it can be selectively selected as a gear pump, a vane pump, a impeller pump, a plunger pump, etc.

[0153] It should be noted that the information acquisition module 2 in the present application includes but is not limited to a carbon dioxide content detection unit, a water cut detection unit, and a corrosion rate detection unit; it can also include other detection units for information acquisition. For example, in specific implementation, the information acquisition module 2 can also selectively include a produced fluid metering unit (or a produced fluid flow rate detection unit), a temperature detection unit, etc.

[0154] In specific implementation, the information processing module 4 calculates the required concentration of corrosion inhibitors in the produced fluid according to the carbon dioxide concentration information, the water cut information, and the corrosion rate information of the produced fluid collected by the information acquisition module 2; and calculates the injection amount and the injection speed of the corrosion inhibitors required by the adjacent next set time period according to the liquid production of the oil well in the set time period, the water cut of the produced fluid of the oil well in the set time period, the required concentration of the corrosion inhibitors in the produced fluid, and the concentration of the corrosion inhibitors injected into the oil well.

[0155] The present application makes the corrosion inhibitor injection device include a control unit 3, and makes the control unit 3 control the corrosion inhibitor injection device according to the information collected by the information acquisition module 2, so that the corrosion inhibitor injection device can process the collected information and automatically adjust the flow of the corrosion inhibitor variable pumping unit 1 according to the processing result, thereby achieving the purpose of automatically adjusting the injection amount and the injection speed of the corrosion inhibitors.

[0156] The present application sets the information processing module 4, and makes the information processing module 4 process the collected carbon dioxide concentration information, water cut information, and corrosion rate information, and further calculates the injection amount of the corrosion inhibitors required in the set time period, and sends the injection amount information to the control unit 3 to control the corrosion inhibitor injection device, thereby realizing the automatic control of the corrosion inhibitor injection device. As a preferred embodiment, the corrosion inhibitor injection device further selectively includes a remote information transmission unit, thereby realizing the remote transmission of information, and making the corrosion inhibitor injection device have the function of remote control to reduce the workload of manual on-site inspection.

[0157] As some preferred embodiments of the present application, the corrosion inhibitor storage unit further selectively includes a liquid storage tank 81 and a heating assembly 82, wherein the liquid storage tank 81 is used to store corrosion inhibitors (such as Figure 3As shown, the heating component 82 is used to heat the corrosion inhibitor in the storage tank 81, and the heating component 82 is connected to the control unit 3 by signal. The information acquisition module 2 also includes a temperature detection unit, which is used to detect the temperature of the corrosion inhibitor in the storage tank 81, and the temperature detection unit is connected to the control unit 3 by signal.

[0158] It should be noted that the structure and shape of the storage tank 81 in this application are not specifically limited. It can be a tank capable of storing a certain amount of corrosion inhibitor. The capacity of the storage tank 81 is selectively set according to the needs of the oil well to be protected, so as to avoid frequent on-site addition of corrosion inhibitor by staff.

[0159] It should be noted that the heating component 82 in this application is not specifically limited; it can be a heating rod (such as a heat pipe) installed inside the storage tank 81 that can heat the corrosion inhibitor. Figure 3 As shown in the figure, it can also be a heating component (not shown) that covers the outer wall of the storage tank 81 and is capable of heating the corrosion inhibitor, such as an electric blanket. In specific implementation, it is preferable to use electric heating for heating; in order to avoid causing a fire, the maximum heating temperature of the heating component is limited to a safe operating temperature range.

[0160] It should be noted that the temperature detection unit in this application is used to detect the temperature of the corrosion inhibitor in the storage tank 81 and is connected to the control unit 3 via a signal connection. In specific implementation, when the temperature of the corrosion inhibitor in the storage tank 81 detected by the temperature detection unit is lower than a set value, the control unit 3 receives the temperature information detected by the temperature detection unit and controls the heating component 82 to heat the corrosion inhibitor to avoid the corrosion inhibitor freezing due to low ambient temperature. Therefore, this application, by setting up a temperature detection unit and a heating component, avoids the corrosion inhibitor freezing due to excessively low temperature and the series of problems caused therefrom.

[0161] As some preferred embodiments of this application, such as Figure 3 As shown, the corrosion inhibitor injection device may be further selectively configured to include an early warning unit 5, which is signal-connected to the carbon dioxide content detection unit and the control unit 3. Preferably, the corrosion inhibitor storage unit may also be further selectively configured to include a level gauge 83, which is signal-connected to the early warning unit 5.

[0162] The application comprises a pre-warning unit 5 in the corrosion inhibitor injection device, and the pre-warning unit 5 is signal connected with the carbon dioxide content detection unit, when the concentration of carbon dioxide collected by the carbon dioxide content detection unit is greater than the set value, the pre-warning unit 5 sends a pre-warning information. The application sets the liquid level meter 83 to monitor the corrosion inhibitor in the corrosion inhibitor storage unit, and further signal connects the liquid level meter 83 with the pre-warning unit 5, and then the liquid level of the corrosion inhibitor can be monitored to send a prompt information to the staff, so that the staff can supplement the corrosion inhibitor in time.

[0163] As some preferred embodiments of the application, the corrosion inhibitor injection device further selectively comprises an information storage module 6, and the information storage module 6 is signal connected with the information acquisition module 2 to store the information collected by the information acquisition module 2.

[0164] The application sets the information storage module 6, and the information collected by the information acquisition module 2 is stored through the information storage module 6, and the stored information is used as an important reference for the oil displacement process and the corrosion prevention process.

[0165] As some preferred embodiments of the application, the corrosion inhibitor injection device further selectively comprises an information remote transmission module 7, and the information remote transmission module 7 is signal connected with the information acquisition module 2 and the control unit 3. The application sets the information remote transmission module 7 to realize the remote transmission function of the information, and signal connects the information remote transmission module 7 with the control unit 3, so that the corrosion inhibitor injection device can be remotely controlled, and the inspection frequency of the staff is reduced.

[0166] The above is only the preferred embodiment of the application, but the protection scope of the application is not limited to this, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A method for preventing corrosion in oil wells in CO2-driven bottom water sandstone reservoirs, characterized in that, The steps include the following: S1: Determine the metal materials that need corrosion protection for oil wells in CO2-driven bottom water sandstone reservoirs; S2: Prepare metal samples based on the metal materials determined in S1, simulate the working conditions of CO2-driven bottom water sandstone reservoirs to conduct corrosion tests, and determine the corrosion factors of the metal samples in oil wells of CO2-driven bottom water sandstone reservoirs. S3: Based on the corrosion factors determined in S2, determine the corrosion resistance of the metal materials used in the oil well under different corrosion conditions; S4: Select a corrosion inhibitor based on the corrosion resistance of the metal material used in the oil well under different corrosion conditions, and load the selected corrosion inhibitor into the corrosion inhibitor injection device; S5: Based on the corrosion resistance of the metal material under different corrosion conditions and the corrosion conditions of the produced fluid in the current set time period, determine the required concentration of corrosion inhibitor in the produced fluid in the current set time period. S6: Based on the concentration of corrosion inhibitor required in the produced fluid during the current set time period determined in S5, determine and adjust the injection amount and injection rate of the corrosion inhibitor injection device in the next adjacent set time period so that the corrosion rate of the oil well is less than 0.076 mm / a. In step S5, the required concentration of corrosion inhibitor in the produced fluid during the current set time period is calculated according to the following formula: Where: C is the required concentration of corrosion inhibitor in the produced fluid; β is the correction factor; V represents the corrosion rate of the produced fluid on the oil well during the current set time period. a represents the percentage of carbon dioxide in the extracted fluid during the currently set time period; η is the water content in the extracted fluid during the currently set time period; C0 is the concentration of corrosion inhibitor required for an oil well to achieve a corrosion rate of 0.076 mm / a.

2. The method for preventing corrosion of oil wells in CO2-driven bottom water sandstone reservoirs according to claim 1, characterized in that, The corrosion factors determined in step S2 include temperature, CO2 partial pressure, flow rate, and crude oil water content. The metal sample is at least one of the following: a sample made of P110S steel, a sample made of P110-13Cr steel, a sample made of P110 steel, and a sample made of N80 steel.

3. The method for preventing corrosion of oil wells in CO2-driven bottom water sandstone reservoirs according to claim 2, characterized in that, In step S2: The selected temperature range is 35℃-120℃; and / or, The CO2 partial pressure is selected within the range of 0.5 MPa-2.0 MPa; and / or, The selected flow velocity range is 0.5 m / s to 2.0 m / s; and / or, The selected range for the water content of the crude oil is 20%-95%.

4. The method for preventing corrosion of oil wells in CO2-driven bottom water sandstone reservoirs according to claim 1, characterized in that, Step S3 includes: S31: Mix crude oil and water evenly according to a set ratio to form an oil-water mixture, and load the oil-water mixture and the metal sample into a reaction vessel; S32: Adjust the temperature inside the reaction vessel to the set temperature, and adjust the pressure inside the reaction vessel to the set pressure; S33: Adjust the flow rate of the oil-water mixture in the reaction vessel according to the set flow rate; S34: Allow the weighed metal sample to react for a set time at a set temperature, a set pressure, and a set flow rate. S35: Remove the metal sample after the reaction, and clean, dry and weigh the metal sample; S36: Determine the corrosion rate of the metal sample based on the mass difference before and after the reaction.

5. The method for preventing corrosion of oil wells in CO2-driven bottom water sandstone reservoirs according to claim 1, characterized in that, In step S6, determining the injection amount of corrosion inhibitor for the next adjacent set time period includes the following steps: S61: Determine the fluid production volume Q1 of the oil well in the current set time period; S62: Determine the water content f in the liquid volume Q1 collected during the current set time period; S63: Determine the concentration C1 of the corrosion inhibitor injected into the oil well in the next adjacent set time period; The injection amount Q of the corrosion inhibitor for the next adjacent set time period is determined according to the following formula:

6. The method for preventing corrosion of oil wells in CO2-driven bottom water sandstone reservoirs according to claim 5, characterized in that, In step S6, corrosion inhibitors are injected into the oil well using a continuous injection method, and the formula for calculating the injection rate v of the corrosion inhibitor in the next adjacent set time period is: Where: t is the duration of the next adjacent set time period.

7. The method for preventing corrosion of oil wells in CO2-driven bottom water sandstone reservoirs according to claim 1, characterized in that, In step S4, the selection of corrosion inhibitor includes the following steps: S41: Select several corrosion inhibitors and conduct water solubility tests on each corrosion inhibitor to determine whether the corrosion inhibitor has an emulsification tendency; S42: Select a corrosion inhibitor with no tendency to emulsify and test the release rate of the corrosion inhibitor under the set conditions; S43: Screen out corrosion inhibitors with a release rate greater than the set value and evaluate the corrosion rate under simulated working conditions; when the corrosion rate of the metal sample is less than 0.076 mm / a, the release inhibitor is qualified; when the corrosion rate of the metal sample is greater than or equal to 0.076 mm / a, the corrosion inhibitor is unqualified.

8. The method for preventing corrosion of oil wells in CO2-driven bottom water sandstone reservoirs according to claim 1, characterized in that, The current set time period is set to any value between 1 hour and 72 hours, and the next set time period is set to any value between 1 hour and 72 hours.

9. A corrosion inhibitor injection device for implementing the oil well corrosion prevention method for CO2-driven bottom water sandstone reservoirs according to any one of claims 1 to 8, characterized in that, The corrosion inhibitor injection device includes: Corrosion inhibitor storage unit, used to store corrosion inhibitor; A corrosion inhibitor variable pumping unit, wherein the corrosion inhibitor storage unit is connected to the annular space between the oil production pipe and the wellbore via the corrosion inhibitor variable pumping unit; The information acquisition module includes a carbon dioxide content detection unit, a water content detection unit, and a corrosion rate detection unit. The carbon dioxide content detection unit is used to detect the carbon dioxide content in the produced fluid, the water content detection unit is used to detect the water content in the produced fluid, and the corrosion rate detection unit is used to detect the rate at which the produced fluid corrodes the oil well. The control unit is signal-connected to the carbon dioxide content detection unit, the moisture content detection unit, and the corrosion rate detection unit; the corrosion inhibitor variable pumping unit is signal-connected to the control unit. An information processing module is used to process the information collected by the information acquisition module; the information processing module is signal-connected to the control unit and the information acquisition module.

Images