Reservoir scaling evaluation method during water injection and its application and device

Abstract

The present invention provides a method for evaluating reservoir scaling during water injection, and its application and device. The evaluation method includes: obtaining the ion concentration and cumulative distribution of solid phase particle size before experimental fluid displacement, and the core permeability of the experimental core before displacement; displacing the experimental core with the experimental fluid, obtaining the multi-point pressure and core permeability of the experimental core during and / or after displacement, the cumulative distribution of solid phase particle size after displacement corresponding to at least two cumulative displacement flow rates, and the ion concentration after displacement; obtaining the change in ion concentration based on the ion concentration before and after displacement; obtaining the minimum retained particle size inside the core based on the cumulative distribution of solid phase particle size before and after displacement; obtaining the scaling location based on the multi-point pressure; obtaining the degree of core damage based on the core permeability before and after displacement; and completing the evaluation of reservoir scaling during water injection. The present invention also provides the application and evaluation device of the above evaluation method.

Description

Technical Field

[0001] The present invention relates to the technical field of oil production engineering, and in particular to a reservoir scaling evaluation method during water injection, and an application and device thereof. Background Art

[0002] With the large-scale water injection development of high-salinity acidic carbonate reservoirs, the water content of the reservoirs has increased, and the amount of produced wastewater has increased. As the demand for water injection has increased, the reinjection of produced wastewater has become the main development method. However, since carbonate reservoirs contain CO2 and H2S acid gases, the produced wastewater contains CO2 and H2S acid gases, resulting in acidic produced water and high mineralization. TDS = (17-28) × 10 4 ppm, resulting in highly corrosive produced water, causing severe corrosion to injection pipelines and physical blockage of reservoirs by corrosion products. Furthermore, hydrogen sulfide, carbon dioxide dissolved in produced water, and iron ions produced by corrosion react chemically with carbonate reservoir rocks and reservoir fluids, leading to the formation of scale or salt crystals. This, in turn, contaminates near-wellbore reservoirs, reduces injection capacity, and increases injection pressure, seriously impacting the effectiveness of water injection development. To decontaminate carbonate reservoirs, acid washing is typically used. However, the residual acid system produced after acid washing enters the reservoir, causing ion concentration disturbances after subsequent injection water and reservoir water mix, potentially leading to scaling and crystallization reactions, and thus secondary contamination of the reservoir.

[0003] Current methods for evaluating reservoir contamination typically include conventional core flooding and the five-sensitivity test. The conventional core flooding method involves flooding a core with injected water of varying quality under simulated reservoir temperature and pressure conditions. The change in core permeability is calculated based on the displacement volume and displacement pressure, thereby determining the impact of the injected water's solids content, oil content, and suspended solids content on the reservoir. This method effectively assesses the extent of reservoir contamination caused by physical blockage of the reservoir by solid impurities in the injected water during injection. However, it cannot monitor the particle size and location of the solid particles blocking the core online, nor can it assess contamination caused by pipe corrosion and water compatibility on reservoir scaling. The five-sensitivity test evaluates the sensitivity of sandstone reservoirs to water, salt, acid, alkali, and flow rate. It is used to assess the sensitivity of sandstone reservoirs to external fluids. However, due to the significant differences in the physical and lithological properties of carbonate rocks and sandstone, the five-sensitivity test cannot effectively assess the contamination characteristics of carbonate reservoirs.

[0004] In summary, current core flooding and five-sensitivity tests cannot effectively evaluate the incompatibility between injected water and formation water, chemical reactions between high-salinity, acidic produced water, reservoir fluids, and reservoir rocks, and chemical interactions between pickling fluids and the reservoir during carbonate waterflooding. However, as large-scale waterflooding of large carbonate reservoirs and reinjection of high-salinity, acidic produced water have become the primary development model for carbonate reservoirs, establishing a scaling contamination evaluation method during carbonate reservoir waterflooding, clarifying the chemical interaction mechanism of the reservoir during waterflooding, and accurately evaluating the permeability changes caused by reservoir scaling are of great guiding significance for waterflooding development. Summary of the Invention

[0005] In order to solve the above problems, the present invention aims to provide a method and application and device for evaluating reservoir scaling during water injection. The evaluation device and evaluation method can effectively evaluate the scaling of carbonate rocks during the reservoir process.

[0006] In order to achieve the above object, the present invention provides a method for evaluating reservoir scaling during water injection, the evaluation method comprising:

[0007] S1. Obtaining the ion concentration and cumulative distribution of solid phase particle size of the experimental fluid before displacement (the cumulative distribution of solid phase particle size is the percentage of solid phases with a solid phase particle size smaller than a certain particle size value in the total solid phase); the experimental fluid includes an acidic fluid and / or a displacement fluid;

[0008] S2. Obtain the core permeability of the experimental core before flooding; flood the experimental core with the experimental fluid, obtain multi-point pressures of the experimental core during and / or after the flooding (i.e., pressures at different positions of the experimental core), obtain the cumulative distribution of solid phase particle sizes after flooding corresponding to at least two cumulative flooding flow rates, and obtain the core permeability of the experimental core during and / or after the flooding, which is recorded as the core permeability after flooding;

[0009] After the displacement is completed, the fluid discharged from the experimental core is tested to obtain the ion concentration after the displacement;

[0010] S3. Obtaining a change in ion concentration based on the ion concentration of the experimental fluid before and after displacement;

[0011] The minimum retained particle size inside the core is obtained based on the cumulative distribution of solid phase particle size before and after displacement of the experimental fluid;

[0012] Obtain the scaling location based on the multi-point pressure of the test core during and / or after the flooding;

[0013] The degree of core damage is obtained based on the core permeability before and after flooding;

[0014] Complete reservoir scaling evaluation during water injection.

[0015] In the above evaluation method, S1 is to collect the parameters of the experimental fluid before displacement, S2 is to use the experimental fluid to displace the core, simulate the fluid injection process in on-site construction, and measure the parameter changes during and after the displacement; S3 is to analyze the data collected by S1 and S2, and evaluate the scaling situation inside the core during the injection of the experimental fluid from four aspects: ion concentration change, minimum retention particle size inside the core, scaling location and degree of core damage, and simulate the scaling situation inside the reservoir during and after the fluid injection.

[0016] In the above-described evaluation method, the test fluid undergoes filtration before entering the fluid container. Specifically, the above-described evaluation method includes filtering the test fluid prior to S1 (filtering the test fluid and then injecting the filtered test fluid into the fluid container). This filtration removes solid particles, such as oil, mud, sand, impurities, and insoluble suspended matter, carried by the test fluid itself, thereby preventing them from affecting the evaluation results. In some specific embodiments, the filter used in the filtration process may have a pore size of 0.45 μm.

[0017] According to a specific embodiment of the present invention, the acidic fluid may include acidic produced wastewater containing dissolved acidic gases and / or a residual acid system obtained after pickling operations. The produced wastewater may be acidic high-salt produced wastewater, such as on-site produced wastewater, indoor simulated produced water, etc. During on-site construction, the acidic fluid contains dissolved acidic gases such as hydrogen sulfide and / or carbon dioxide, which are corrosive and will corrode the metal pipes along the way during transportation. The corrosion products will affect the water quality of the acidic fluid, and the ion type and ion concentration in the acidic fluid will change. At the same time, scale will be generated, increasing the solid content in the water. The above changes will lead to scaling and contamination of the reservoir.

[0018] In some specific embodiments, when the test fluid includes an acidic fluid, the evaluation method may further include performing step S0 before step S1: utilizing the acidic fluid to corrode the metal product to simulate the corrosion process, and using the acidic fluid after the simulated corrosion process as the test fluid. Furthermore, step S0 may include first filtering the acidic fluid, and then using the filtered acidic fluid to simulate the corrosion process.

[0019] In some specific embodiments, the simulated corrosion process can be performed in a high-temperature autoclave. Prior to performing the simulated corrosion process, step S0 can further include calculating the partial pressure of the acidic gas in the acidic fluid based on the concentration of the acidic gas dissolved in the on-site acidic fluid, introducing the acidic gas into the acidic fluid in the high-temperature autoclave based on the partial pressure, and maintaining the pressure within the autoclave constant during the corrosion process. In some specific embodiments, nitrogen can be injected into the high-temperature autoclave to adjust the total pressure within the autoclave, and the temperature and pressure within the autoclave can be controlled by temperature and pressure control equipment connected to the high-temperature autoclave to maintain a constant concentration of the acidic gas in the acidic fluid.

[0020] According to specific embodiments of the present invention, the displacement fluid can be used to simulate the degree of scaling contamination of the reservoir by different types of injected fluids. In some specific embodiments, the displacement fluid can include one or a combination of two or more of river water, seawater, and formation water. In some specific embodiments, the displacement fluid can be used after being deoxygenated (e.g., after deoxygenation, it is injected into a fluid storage tank).

[0021] According to a specific embodiment of the present invention, the above-mentioned evaluation method can be used to simulate scaling in a reservoir using a single fluid, that is, to flood a test core with either an acidic fluid or a displacement fluid. In this case, S1 may include obtaining the ion concentration and cumulative distribution of solid phase particle size of the acidic fluid or the displacement fluid before displacement; S2 may include flooding a test core with either the acidic fluid or the displacement fluid alone, and obtaining the ion concentration, cumulative distribution of solid phase particle size, and core permeability after the displacement.

[0022] According to a specific embodiment of the present invention, the above-described evaluation method can be used to simulate scaling in reservoirs using mixed fluids. In this case, S1 includes measuring the ion concentration and cumulative distribution of solid phase particle size of the acidic fluid and the displacement fluid before displacement. S2 involves flooding the experimental core with the experimental fluid, which includes alternating the acidic fluid and the displacement fluid in the same experimental core. The number of alternating cycles between the acidic fluid and the displacement fluid can be determined based on actual needs.

[0023] In some specific embodiments, when the acidic fluid is a residual acid system after a pickling operation, the alternating displacement process may include: cyclically displacing the experimental core in the order of displacement fluid-acidic fluid to simulate the scaling of the reservoir during the "water injection-pickling-water injection" cycle during field construction.

[0024] In some specific embodiments, when the acidic fluid is acidic produced water, there is no special requirement for the injection sequence of acidic produced water and displacement fluid, and the alternating displacement process may include: cyclically displacing the experimental core in the order of acidic fluid-displacement fluid or displacement fluid-acidic fluid.

[0025] According to a specific embodiment of the present invention, the ion concentrations before and after the flooding are generally the concentrations of various types of ions. The ion concentration change is the difference between the ion concentration before and after the flooding, that is, ion concentration change = ion concentration after flooding - ion concentration before flooding.

[0026] According to a specific embodiment of the present invention, when S2 is used as the experimental fluid to displace the experimental core alone using acidic fluid or displacement fluid, the ion concentration before displacement and the ion concentration after displacement are the results obtained by directly measuring the ion concentration of the experimental fluid before / after displacement, and the ion concentration can be measured by an ion concentration online monitor.

[0027] According to a specific embodiment of the present invention, when S2 is a mixed fluid using acidic fluid and displacement fluid to alternately displace the same experimental core, the ion concentration before displacement is a weighted average of the ion concentration before displacement of the acidic fluid and the ion concentration before displacement of the displacement fluid, wherein the weighting coefficient is determined based on the total displacement flow of the acidic fluid and the total displacement flow of the displacement fluid during the alternating displacement process.

[0028] According to a specific embodiment of the present invention, for the alternating displacement process, the calculation method of the ion concentration change can be:

[0029] Ion concentration change = C1-C0,

[0030] Where: C0=(C 10 ×a+C 20 ×b) / (a+b);

[0031] C0 is the ion concentration before displacement, C1 is the ion concentration after displacement (the ion concentration measured after the last displacement), C 10 is the ion concentration before displacement of acidic fluid, C 20 is the ion concentration of the displacement fluid before displacement, C0, C1, C 10 、C 20 The unit of a is the same, for example, mg / L; the ratio of a to b is equal to the ratio of the total displacement flow of the acidic fluid in the alternating displacement process to the total displacement flow of the displacing fluid in the alternating displacement process.

[0032] According to a specific embodiment of the present invention, when S2 undergoes an alternating displacement process, the ion concentration after displacement is the ion concentration of the fluid discharged from the core during the last displacement. For example, if the displacement is performed in an "acidic fluid-displacing fluid" alternating manner, the ion concentration after displacement is obtained by measuring the ion concentration of the displacing fluid during the last displacement; if the displacement is performed in a "displacing fluid-acidic fluid" alternating manner, the ion concentration after displacement is obtained by measuring the ion concentration of the acidic fluid during the last displacement.

[0033] According to a specific embodiment of the present invention, a method for evaluating reservoir scaling based on ion concentration changes can include: ions with an ion concentration change of less than 0 are considered scaling ions. An ion concentration change of less than 0 corresponds to a decrease in the content of the corresponding ion in the fluid discharged after displacement, indicating that the ion in the fluid remains in the experimental core and forms scaling. Therefore, ions with an ion concentration change of less than 0 are considered scaling ions.

[0034] According to specific embodiments of the present invention, the aforementioned ion concentration changes can also be used to evaluate the compatibility between two or more fluids. For example, if two or more fluids are alternately displacing a test core, and the calculated ion concentration changes for most anions and cations are less than 0, this may be due to the tendency for inorganic scaling to form after mixing the different fluids, indicating significant incompatibility between the fluids.

[0035] According to a specific embodiment of the present invention, the above-mentioned evaluation method may include obtaining D90 based on the cumulative distribution of solid phase particle size, where D90 is the particle size corresponding to the cumulative distribution frequency of particle size reaching 90%; the minimum retained particle size inside the core is determined based on D90 before displacement and D90 after displacement. In some specific embodiments, the minimum retained particle size inside the core is the largest D90 particle size among D90 before displacement and D90 after displacement. According to a specific embodiment of the present invention, the collection of the cumulative distribution of solid particle size needs to meet the following conditions: at least one cumulative displacement flow corresponding to D90 after displacement is greater than the cumulative displacement flow corresponding to the minimum retention rate of the core. That is, the cumulative displacement flow corresponding to D90 before displacement is 0, and in all D90 data collected by S1 and S2, as the cumulative displacement flow increases, D90 first increases and then decreases. Accordingly, during the data collection process of S2, at least D90 must first increase (the increase can be relative to D90 before displacement, or relative to D90 with a smaller cumulative displacement flow rate) and then decrease before the collection of the cumulative distribution of solid particle size after displacement can be stopped.

[0036] The minimum retention particle size determined by the present invention is the inflection point of the D90 particle size during the process of increasing the cumulative displacement flow. The cumulative displacement flow corresponding to the minimum retention particle size is m. When the cumulative displacement flow increases from 0 to m, scale will be formed between the fluid used for displacement and the core, or the fluid used for displacement (such as between the acidic fluid and the displacement fluid and the rock in the alternating displacement process). With the increase of the cumulative displacement flow, the scaling growth causes the particle size to grow. Although new scale is constantly generated, the overall embodiment is that the proportion of large particle size increases and D90 increases. When the cumulative displacement amount reaches more than m, the core is significantly blocked due to scaling accumulation. At this time, the solid phase of large particle size is blocked in the core, and the number of solid phase particles discharged from the core is reduced, and the proportion of small particle size is increased, so D90 is reduced. The D90 when the cumulative displacement flow is m is the inflection point in all D90 data. At this time, the solid phase of the solid phase particles with a particle size greater than the D90 begins to be trapped in the core due to core blockage, so the D90 is used as the minimum retention particle size.

[0037] According to a specific embodiment of the present invention, the cumulative displacement flow rate m corresponding to the minimum retained particle size can be used as the minimum displacement flow rate for reservoir scaling and contamination damage, representing the optimal flow rate for a single operation in scale prevention or descaling measures. Injecting a fluid flow rate of m into the reservoir prevents scale formation and core clogging. Injecting a fluid flow rate greater than m can cause scaling and contamination of the reservoir.

[0038] According to a specific embodiment of the present invention, when S2 performs an alternating displacement process, the cumulative distribution of the solid phase particle size before displacement is a weighted average of the solid phase particle size distribution before displacement of the acidic fluid and the cumulative distribution of the solid phase particle size before displacement of the displacing fluid, and the weighting coefficient is determined according to the total displacement flow of the acidic fluid and the total displacement flow of the displacing fluid during the alternating displacement process.

[0039] According to a specific embodiment of the present invention, when S2 is an alternating displacement process, the calculation formula for the minimum retained particle size D inside the core is:

[0040] D=max{(D90)0,(D90) N}

[0041] Among them, D90 is the particle size corresponding to the cumulative distribution frequency of particle size reaching 90%, (D90)0 is the D90 before displacement, (D90) N is the D90 after displacement measured by performing N cycles of alternating displacement, where N is a natural number greater than or equal to 1;

[0042] (D90)0=((D90) 10 ×a+(D90) 20 ×b) / (a+b);

[0043] (D90) 10D90 is the D90 particle size before acidic fluid displacement, (D90) 20 is the D90 particle size before displacement by the displacement fluid, and the ratio of a to b is equal to the ratio of the total displacement flow rate of the acidic fluid during the alternating displacement process to the total displacement flow rate of the displacement fluid during the alternating displacement process.

[0044] According to a specific embodiment of the present invention, the cumulative distribution of the solid phase particle size after displacement can be measured after each cycle of alternating displacement. That is, N in the above formula for the minimum retained particle size inside the core can take all integers from 1 to n, where n is the total number of cycles, so as to obtain more D90 particle size data after displacement and improve the accuracy of the judgment of the minimum retained particle size inside the core.

[0045] According to a specific embodiment of the present invention, when S2 performs an alternating displacement process, the cumulative distribution of solid phase particle sizes after displacement is the cumulative distribution of solid phase particle sizes of the fluid discharged from the core measured after each cyclic displacement.

[0046] According to a specific embodiment of the present invention, the multi-point pressure of the experimental core includes one or a combination of two or more of the head end pressure, middle pressure and end pressure of the core.

[0047] According to a specific embodiment of the present invention, the method for determining the location of reservoir scaling using multi-point pressures is to compare the multi-point pressures of the experimental core corresponding to the same displacement flow rate and select the location with the highest pressure as the scaling location. The displacement flow rate corresponding to the multi-point pressures is the total cumulative flow rate of the acidic fluid and the displacement fluid. For example, if the displacement flow rates of the acidic fluid and the displacement fluid are 5 PV respectively, and the total cumulative flow rate is 10 PV, then the displacement flow rate corresponding to the measured multi-point pressures is 10 PV. In some specific embodiments, the multi-point pressures of one displacement flow rate or two or more displacement flow rates can be measured as needed.

[0048] According to a specific embodiment of the present invention, the method for calculating the core damage degree may be:

[0049] λ=(K0-K) / K0×100%,

[0050] Where λ is the core damage degree, K is the core permeability after flooding, and K0 is the core permeability before flooding. Based on the core damage degree calculated above, the extent of reservoir damage during fluid injection can be evaluated.

[0051] According to a specific embodiment of the present invention, the calculation method of the core permeability can be:

[0052] K=ΔP×A / (Q×μ×L)

[0053] ΔP is the pressure difference between the front and back ends of the fluid passing through the rock (i.e., the absolute value of the pressure difference between the inlet and outlet ends of the core clamping device), MPa; A is the cross-sectional area of ​​the fluid passing through the rock, cm 2 ; Q is the flow rate of fluid through the core per unit time, cm 3 / s; μ is the viscosity of the fluid; L is the length of the core, cm.

[0054] According to a specific embodiment of the present invention, the core permeability after displacement is generally calculated using the above method, and the core permeability before displacement can be calculated using the above formula. The fluid used to measure the core permeability before displacement is generally clean water; or, if the experimental core is a standard core, the core permeability of the experimental core is known.

[0055] According to a specific embodiment of the present invention, the core permeability after displacement can be calculated based on parameters collected during the displacement process, or can be calculated based on parameters collected during the last displacement.

[0056] The present invention also provides a reservoir scaling evaluation device during water injection, the evaluation device comprising: a fluid container, a core clamping device, and a detection system;

[0057] The core holding device includes a core holder having a pressure measuring hole;

[0058] The detection system includes an ion concentration online monitor and a particle size analyzer that are connected to each other;

[0059] The outlet of the fluid container is connected to the inlet of the core clamping device and the inlet of the detection system respectively, and the outlet of the core clamping device is connected to the detection system.

[0060] According to a specific embodiment of the present invention, valves may be provided between the outlet of the fluid container and the inlet of the core clamping device, between the outlet of the fluid container and the inlet of the detection system, and between the outlet of the core clamping device and the inlet of the detection system.

[0061] According to a specific embodiment of the present invention, the fluid container is used to hold the experimental fluid. The fluid container may specifically include a high-temperature and high-pressure autoclave and a liquid storage tank, wherein the high-temperature and high-pressure autoclave is used to hold the acidic fluid, and the liquid storage tank is used to hold the displacement fluid. Accordingly, the outlet of the high-temperature and high-pressure reactor can be connected to the inlet of the core clamping device and the inlet of the detection system respectively; the outlet of the liquid storage tank can be connected to the inlet of the core clamping device and the inlet of the detection system respectively. In some specific embodiments, valves may be provided between the outlet of the high-temperature and high-pressure reactor and the inlet of the core clamping device, between the outlet of the high-temperature and high-pressure reactor and the inlet of the detection system, between the outlet of the liquid storage tank and the inlet of the core clamping device, and between the outlet of the liquid storage tank and the inlet of the detection system.

[0062] According to a specific embodiment of the present invention, the acidic fluid contained in the high-temperature autoclave has a certain degree of corrosiveness and can undergo a corrosion process with metal products (such as metal hanging plates, etc.) to simulate the corrosion effect of the acidic fluid used on site (such as highly corrosive high-hydrochloric acid produced water, residual acid system after acidification operation, etc.) on metal pipes during transportation. The corrosion products and related ions formed by the above corrosion process will affect the scaling process inside the reservoir. By simulating the above corrosion process, it is helpful to improve the accuracy of the evaluation of the scaling situation of the reservoir during the water injection process. In some specific embodiments, hanging plates can be hung in the high-temperature autoclave. Furthermore, the high-temperature autoclave can also be connected to temperature and pressure control equipment to control the temperature and pressure in the autoclave. After the corrosion process is completed, the ion concentration and solid content of the strongly acidic fluid in the autoclave will change. The above parameters of the acidic fluid can be detected using the ion concentration online monitor and particle size analyzer in the detection system.

[0063] According to a specific embodiment of the present invention, the fluid storage tank may be connected to a heating device to adjust the temperature of the displacement fluid to simulate the injection water temperature in the field. The injection water temperature is generally 10-30°C lower than the formation temperature. Accordingly, the temperature of the displacement fluid in the fluid storage tank can be 10-30°C lower than the formation temperature.

[0064] According to a specific embodiment of the present invention, in the core clamping device, the pressure measuring hole can be connected to an external pressure sensor, so that the pressure at different positions of the core can be detected in real time by using the pressure measuring hole.

[0065] According to a specific embodiment of the present invention, depending on the type of experimental fluid, the core clamping device may include one or more core clamps with pressure taps, each core clamp having an inlet for receiving the experimental fluid and an outlet for discharging the experimental fluid. In some specific embodiments, the core clamping device includes a first core clamp and / or a second core clamp. The inlet of the first core clamp is connected to the outlet of the high-temperature and high-pressure autoclave, the inlet of the second core clamp is connected to the outlet of the fluid storage tank, and the outlets of the first and second core clamps are respectively connected to a detection system.

[0066] According to a specific embodiment of the present invention, the core holder (first and second core holders) is a core holder with two or more pressure taps, capable of continuously monitoring the pressure at multiple locations within the core in real time. Pressure changes at various locations within the core holder can indicate the location of scaling and blockage, and determine the depth of scaling contamination.

[0067] In some specific embodiments, the core holder having the pressure measuring hole may be connected to a pressure control device, which can be used to simulate the formation confining pressure so that the core in the core holder can simulate the reservoir under the formation pressure environment.

[0068] In some specific embodiments, the inlet and outlet ends of the core holder having the pressure measuring hole may be connected to pressure sensors respectively for detecting the pressure difference between the two ends of the core holder.

[0069] In the above specific embodiment, the temperature and pressure control equipment connected to the high-temperature and high-pressure autoclave, the heating equipment connected to the liquid storage tank, and the pressure control equipment connected to the core clamp with a pressure measuring hole can constitute the temperature and pressure control system in the above evaluation device.

[0070] According to a specific embodiment of the present invention, the outlet of the high-temperature and high-pressure reactor is optionally connected to the inlet of the first core holder, the inlet of the detection system, or the inlet of the second core holder; the outlet of the liquid storage tank is optionally connected to the inlet of the second core holder, the inlet of the detection system, or the inlet of the first core holder.

[0071] According to a specific embodiment of the present invention, the evaluation device may further include a connection system, which can control the connection relationship between the fluid container and the core clamping device and the detection system respectively, thereby simulating the scaling process inside the reservoir after different types of fluids are injected into the reservoir.

[0072] According to a specific embodiment of the present invention, the evaluation device includes a first multi-way valve, a second multi-way valve, and a third multi-way valve. The first multi-way valve can directly control the connection between the high-temperature autoclave and the first core holder, and the first multi-way valve and the second multi-way valve can jointly control the connection between the high-temperature autoclave and the detection system; the third multi-way valve can directly control the connection between the liquid storage tank and the second core holder, and the second multi-way valve and the third multi-way valve can jointly control the connection between the liquid storage tank and the detection system; the first multi-way valve, the second multi-way valve, and the third multi-way valve can jointly control the connection between the high-temperature autoclave and the second core holder, and the first multi-way valve, the second multi-way valve, and the third multi-way valve can jointly control the connection between the liquid storage tank and the first core holder.

[0073] According to a specific embodiment of the present invention, the first multi-way valve is provided in the connecting pipeline between the high-temperature autoclave and the first core holder, and the first multi-way valve is also connected to the second multi-way valve. That is, the first multi-way valve is respectively connected to the outlet of the high-temperature autoclave, the second multi-way valve, and the inlet of the first core holder. The first multi-way valve has at least three passages and can be a three-way valve.

[0074] According to a specific embodiment of the present invention, the third multi-way valve is provided in the connecting pipeline between the liquid storage tank and the second core holder, and the third multi-way valve is also connected to the second multi-way valve. That is, the third multi-way valve is respectively connected to the outlet of the liquid storage tank, the second multi-way valve, and the inlet of the second core holder. The third multi-way valve has at least three passages and can be a three-way valve.

[0075] According to a specific embodiment of the present invention, the second multi-way valve is connected to the first multi-way valve, the detection system, and the third multi-way valve respectively. The second multi-way valve has at least three passages and can be a three-way valve.

[0076] In some specific embodiments, the second multi-way valve may also be connected to an emptying device for discharging fluid from equipment such as a detection system. In this case, the second multi-way valve has at least four passages and may be a four-way valve.

[0077] According to a specific embodiment of the present invention, the detection system specifically includes an online ion concentration monitor and a particle size analyzer. The online ion concentration monitor can detect the concentrations of different ions in the experimental fluid. The particle size analyzer can detect the cumulative distribution of solid phase particle size in the experimental fluid and can also detect the particle size distribution frequency.

[0078] According to the above specific embodiment, the evaluation device of the present invention may specifically include: a high temperature and high pressure autoclave, a liquid storage tank, a first core holder, a second core holder, a detection system and a connection system;

[0079] The high-temperature autoclave is used to contain the acidic fluid;

[0080] The liquid storage tank is used to contain the displacement fluid;

[0081] The first core holder and the second core holder are core holders with pressure measuring holes, respectively, and the core holders with pressure measuring holes can detect the multi-point pressure of the core in real time;

[0082] The detection system includes an ion concentration online monitor and a particle size analyzer;

[0083] The connection system includes a first multi-way valve, a second multi-way valve, and a third multi-way valve;

[0084] The first multi-way valve is connected to the second multi-way valve, the outlet of the high-temperature and high-pressure autoclave, and the inlet of the first core holder respectively;

[0085] The second multi-way valve is connected to the first multi-way valve, the detection system, and the third multi-way valve;

[0086] The third multi-way valve is connected to the outlet of the second multi-way valve liquid storage tank and the inlet of the second core holder respectively;

[0087] The outlet of the first core holder and the outlet of the second core holder are connected to a detection system respectively.

[0088] According to a specific embodiment of the present invention, the evaluation device may further include a fourth multi-way valve. The fourth multi-way valve is part of a connection system and is respectively connected to the outlet of the first core holder, the outlet of the second core holder, and the inlet of the detection system. That is, the outlet of the first core holder and the outlet of the second core holder are respectively connected to the detection system via the fourth multi-way valve. In some specific embodiments, the fourth multi-way valve has at least three passages and may be a three-way valve.

[0089] In some specific embodiments, the fourth multi-way valve can also be connected to an emptying device for discharging the fluid in the core clamping device (the first core clamp, the second core clamp) and the detection system. In this case, the fourth multi-way valve has at least four passages and can be a four-way valve; alternatively, a fifth multi-way valve can be arranged between the fourth multi-way valve (having at least three passages) and the core clamping device. The fifth multi-way valve is respectively connected to the fourth multi-way valve, the core clamping device, and the emptying device. On the one hand, it controls the relationship between the fourth multi-way valve and the core clamping device, and on the other hand, it can discharge the fluid in the core clamping device and the detection device.

[0090] According to a specific embodiment of the present invention, the connection system further comprises at least one horizontal flow pump, which is provided between the first multi-way valve and the inlet of the first core holder and / or between the third multi-way valve and the inlet of the second core holder.

[0091] According to a specific embodiment of the present invention, the connection system also includes at least one circulation pump, which can be arranged in one or a combination of two or more of the following positions: between the outlet of the first core clamp and the detection system, between the online ion concentration detector and the particle size analyzer, between the outlet of the liquid storage tank and the third multi-way valve, and between the outlet of the second core clamp and the fourth multi-way valve.

[0092] According to a specific embodiment of the present invention, the connection system may further include a pipeline, which is used to connect the above-mentioned devices in the system. The pipeline can be specifically a temperature-resistant, pressure-resistant and corrosion-resistant pipeline.

[0093] The above-mentioned evaluation device can implement the above-mentioned evaluation method provided by the present invention.

[0094] The present invention also provides the application of the aforementioned evaluation method to assess reservoir scaling during carbonate rock water injection. During carbonate rock development, produced wastewater is typically high-salinity, acidic produced wastewater containing dissolved acidic gases. The evaluation method provided by the present invention is suitable for evaluating scaling in reservoirs caused by the injection of high-salinity, acidic produced wastewater.

[0095] The beneficial effects of the present invention are:

[0096] The evaluation method provided by the present invention can simulate the on-site water injection process and is used to evaluate the degree of scaling contamination caused by different injection water sources and post-acidification water injection during reservoir waterflooding. Ion concentration and particle size analysis are used to analyze changes in water quality during the displacement process, revealing the patterns and influencing factors of reservoir scaling. This evaluation method can simulate both dynamic and static scaling processes and is applicable to scaling contamination assessment during waterflooding in carbonate reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 Schematic diagram of the evaluation device structure of Example 1.

[0098] Explanation of symbols: high-temperature and high-pressure autoclave 1, stirring rod 11, metal hanging piece 12, liquid storage tank 2, first core clamp 3, second core clamp 4, ion concentration online monitor 5, particle size analyzer 6, first multi-way valve 71, second multi-way valve 72, third multi-way valve 73, fourth multi-way valve 74, fifth multi-way valve 75, first horizontal flow pump 81, second horizontal flow pump 82, first circulation pump 91, second circulation pump 92, third circulation pump 93, fourth circulation pump 94, pipelines: L1, L3 to L8. DETAILED DESCRIPTION

[0099] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0100] In the description of the invention, it should be understood that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the invention, unless otherwise specified, "several" means one or more than two.

[0101] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two components.

[0102] Example 1

[0103] This embodiment provides a reservoir scaling evaluation device during water injection, such as Figure 1 As shown, the evaluation device includes: a fluid container, a core clamping device, a detection system, a connection system and a temperature and pressure control system.

[0104] The fluid container includes a high-temperature autoclave 1 and a liquid storage tank 2.

[0105] The autoclave 1 is used to contain acidic fluids. A metal hanger 12 is suspended within the autoclave. The corrosive fluid and the hanger corrode within the autoclave, simulating the composition of acidic produced water injected into the formation or the residual acid system generated after pickling operations. A stirring rod 11 can also be provided within the autoclave to agitate the acidic fluid during the corrosion process, simulating a dynamic corrosion process.

[0106] The liquid storage tank 2 is used to contain displacement fluid, such as injection water such as river water, seawater, formation water, etc. The number of liquid storage tanks 2 is adjusted according to the actual situation such as the type of displacement fluid. In this embodiment, two liquid storage tanks 2 are provided.

[0107] The core clamping device includes a first core holder 3 and a second core holder, which are used to hold and secure the core. Both the first core holder 3 and the second core holder are equipped with pressure taps, enabling real-time monitoring of pressure at various locations on the core, i.e., multi-point pressure. In this embodiment, the core holder with pressure taps is equipped with pressure taps at both ends and in the middle of the core, enabling pressure measurement at both ends (head and tail) and in the middle of the core.

[0108] The inlet and outlet pipelines of the first core holder 3 and the inlet and outlet pipelines of the second core holder 4 may also be provided with pressure sensors for measuring the pressure difference between the two ends (inlet end and outlet end) of the first core holder 3 and the second core holder 4 .

[0109] The detection system includes an online ion concentration monitor 5 and a particle size analyzer 6. The online ion concentration monitor 5 enables rapid and continuous online monitoring of key anion and cation concentrations, while the particle size analyzer 6 monitors the particle size distribution in the fluid (including the cumulative distribution of solid particle sizes and the distribution frequency of each particle size range). The online ion concentration monitor 5 and particle size analyzer 6 are interconnected.

[0110] The temperature and pressure control system can be considered the sum of the supporting equipment of the high-temperature and high-pressure reactor, the liquid storage tank 2, and the core holder with a pressure measuring hole. The temperature and pressure control system includes temperature and pressure control equipment, heating equipment, and pressure control equipment.

[0111] The temperature and pressure control equipment is connected to the high-temperature and high-pressure autoclave 1 and is used to control the pressure and temperature in the autoclave to keep the acid gas content in the acidic fluid constant.

[0112] The heating device is connected to the liquid storage tank 2 and can adjust the temperature of the displacement fluid to simulate the injection water temperature on site.

[0113] The pressure control device is connected to the multi-point core holder to simulate the formation confining pressure.

[0114] The connection system includes temperature-resistant, pressure-resistant and corrosion-resistant pipelines, a first multi-way valve 71, a second multi-way valve 72, a third multi-way valve 73, a fourth multi-way valve 74, a fifth multi-way valve 75, a first horizontal flow pump 81, a second horizontal flow pump 82, a first circulation pump 91, a second circulation pump 92, a third circulation pump 93, and a fourth circulation pump 94.

[0115] The first multi-way valve 71 is a three-way valve, the second multi-way valve 72 is a four-way valve, and the third multi-way valve 73 is a three-way valve. The first, second, and third multi-way valves 71, 72, and 73 are used to coordinately control the connections between the high-temperature autoclave 1, the liquid storage tank 2, the first core holder 3, the second core holder 4, and the detection system.

[0116] The fourth multi-way valve 74 is used to control the connection relationship between the first core holder 3, the second core holder 4 and the detection system respectively.

[0117] The fifth multi-way valve 75 is used to discharge liquid from the first core holder 3, the second core holder 4 and the detection system.

[0118] The temperature-resistant, pressure-resistant and corrosion-resistant pipelines are used to connect the above-mentioned equipment, including pipeline L1, pipeline L3, pipeline L4, pipeline L5, pipeline L6, pipeline L7 and pipeline L8.

[0119] The first multi-way valve 71 is connected to the outlet of the high-temperature autoclave 1 through a pipeline L1, connected to the second multi-way valve 72 through a pipeline L3, and connected to the inlet of the first core holder 3 through a pipeline L6.

[0120] The second multi-way valve 72 is connected to the first multi-way valve 71, and is connected to the third multi-way valve 73 via pipeline L5, and is connected to the ion concentration online monitor 5 via pipeline L7. In addition, the second multi-way valve 72 is also connected to the drain device for draining the fluid discharged from the ion concentration online monitor 5.

[0121] The third multi-way valve 73 is connected to the second multi-way valve 72 and the inlet of the second core holder 4 respectively, and is connected to the outlet of the liquid storage tank 2 through the pipeline L4.

[0122] The fourth multi-way valve 74 is connected to the outlet of the first core holder 3 , the particle size analyzer 6 , and the fifth multi-way valve 75 .

[0123] The fifth multi-way valve 75 is connected to the fourth multi-way valve 74 and connected to the outlet of the second core holder 4 through the pipeline L8. In addition, the fifth multi-way valve 75 is also connected to the emptying device for emptying the fluid discharged from the core holding device and the detection system.

[0124] The first horizontal flow pump 81 is arranged at the head end of the first core clamp 3, on the pipeline L6 between the inlet of the first core clamp 3 and the first multi-way valve 71. The second horizontal flow pump 82 is arranged at the head end of the second core clamp 4, between the inlet of the second core clamp 4 and the third multi-way valve 73, and is used to provide power for the injected fluid.

[0125] The first circulation pump 91 is arranged between the first core clamp 3 and the fourth multi-way valve 74, the second circulation pump 92 is arranged between the particle size analyzer 6 and the ion concentration online monitor 5, the third circulation pump 93 is arranged at the outlet end of the liquid storage tank 2, the pipeline L4 between the outlet of the liquid storage tank 2 and the third multi-way valve 73, and the fourth circulation pump 94 is arranged at the end of the second core clamp 4, the pipeline L8 between the second core clamp 4 and the fifth multi-way valve 75. The above-mentioned circulation pumps provide power for the fluid transported in the system.

[0126] The evaluation methods of the following Examples 2 to 5 are all implemented using the evaluation device of Example 1.

[0127] Example 2

[0128] This embodiment provides a method for evaluating reservoir scaling during water injection using acidic fluid displacement alone, the method comprising the following steps:

[0129] 1. Collect produced wastewater on-site. Based on a hydrogen sulfide content of 120 ppm, calculate the partial pressure of the acidic gas hydrogen sulfide to be 0.6 MPa. Introduce nitrogen and hydrogen sulfide, maintaining a total pressure of 4 MPa and an H2S partial pressure of 0.6 MPa. Filter the produced wastewater through a filter with a pore size of 0.45 μm.

[0130] A hanging plate was placed in the high-temperature and high-pressure autoclave 1, and filtered produced wastewater was injected. The temperature in the high-temperature and high-pressure autoclave 1 was controlled at 60°C and the H2S partial pressure was 0.6 MPa to maintain the dissolved hydrogen sulfide content in the solution system. Dynamic stirring was started to simulate the flow process of produced water in the metal pipe column before injection into the formation. The stirring was maintained for one week to allow a certain degree of corrosion to occur between the acidic produced water and the hanging plate, thereby obtaining simulated produced wastewater.

[0131] 2. By adjusting the first multi-way valve 71 and the second multi-way valve 72, the connection between the high-temperature autoclave 1 and the detection system is opened, and the produced wastewater is simulated to flow out of the high-temperature autoclave 1, through the pipeline L1, the first multi-way valve 71, the pipeline L3, the second multi-way valve 72 and the pipeline L7 to the ion concentration online monitor 5 and the particle size analyzer 6 in sequence. The ion concentration C of the produced wastewater before displacement is measured by the ion concentration online monitor 5 and the particle size analyzer 6. 10 and the cumulative distribution of solid phase particle size D 10 After the measurement is completed, the connection between the high-temperature autoclave 1 and the detection system is disconnected, and the produced wastewater is discharged from the device through the fourth multi-way valve 74 and the fifth multi-way valve 75;

[0132] The core in the first core holder 3 is used as an experimental core (simulating a carbonate reservoir), and the core permeability K0 of the experimental core before displacement is measured using clean water. If the experimental core is a standard core, the core permeability K0 before displacement is known.

[0133] 3. Regulate the first multi-way valve 71 and the second multi-way valve 72 to open the connection between the high-temperature autoclave 1 and the first core holder 3, and use the produced wastewater to displace the experimental core. After the displacement is completed, disconnect the connection between the high-temperature autoclave 1 and the first core holder 3;

[0134] Using the first core holder 3 to measure the multi-point pressure corresponding to at least one displacement flow rate during or at the end of the displacement, the pressure measurement positions include the core head end, the core middle end, and the core end;

[0135] The ion concentration C1 and the cumulative distribution of solid phase particle size D1 after the displacement are measured using an online ion concentration detector 5 and a particle size analyzer 6 (corresponding to at least two cumulative displacement flow rates; as the displacement flow rate increases, D90 in the cumulative distribution of solid phase particle size after displacement should be observed to first increase and then decrease). The test results of D1 including D90 are recorded, and the total displacement flow rate of the produced wastewater is recorded. The pressure difference between the inlet and outlet of the first core holder 3 is measured using a pressure sensor.

[0136] 4. Using the ion concentration C of the produced wastewater before displacement 10 , the ion concentration C1 after displacement alone is used to calculate the ion concentration change ΔC, and the calculation formula is:

[0137] ΔC=C1-C0,

[0138] Where: C0=C 10 .

[0139] Ions with concentration changes less than 0 are considered to be scaling ions within the core. Ions with large absolute ΔC values ​​indicate a high degree of scaling, potentially causing pressure changes within the core.

[0140] 5. Compare the cumulative distribution of solid phase particle size before displacement D 10 The largest D90 is selected as the minimum retained particle size within the core. This refers to the particle size at which scaling products larger than this size will remain in the core, blocking seepage channels and causing core contamination. The cumulative displacement flow rate corresponding to this particle size is defined as the minimum displacement flow rate for reservoir scaling contamination. This cycle represents the optimal displacement flow rate for implementing on-site deblocking, anti-scaling, and descaling measures.

[0141] 6. Compare the pressures at multiple points corresponding to the same displacement flow rate and select the location with the highest pressure as the location where scaling occurs.

[0142] 7. Calculate the permeability of the core after displacement:

[0143] K=ΔP×A / (Q×μ×L)

[0144] ΔP is the pressure difference between the front and rear ends of the fluid passing through the rock at the end of displacement (i.e., the absolute value of the pressure difference between the inlet and outlet of the first core holder 3), MPa; A is the cross-sectional area of ​​the fluid passing through the rock, cm 2 ; Q is the flow rate of fluid through the core per unit time, cm 3 / s; μ is the viscosity of the displacement fluid; L is the length of the core, cm.

[0145] Calculate the degree of core damage:

[0146] λ=(K0-K) / K0×100%

[0147] Where λ is the core damage degree, K is the core permeability after flooding, and K0 is the core permeability before flooding. The core damage degree λ is used to evaluate the degree of reservoir scaling caused by the water injection process.

[0148] The above process completed the evaluation of the scaling condition of carbonate reservoirs caused by the injection of produced wastewater alone into the reservoir through four aspects: changes in ion concentration, retention rates in different particle size ranges, scaling locations indicated by multi-point pressure, and the degree of core damage.

[0149] This embodiment also provides a method for evaluating reservoir scaling during water injection using seawater displacement alone, the method comprising the following steps:

[0150] 1. Filter seawater using a filter with a pore size of 0.45 μm and inject the filtered seawater into the liquid storage tank 2; open the connection between the liquid storage tank 2 and the detection system by adjusting the third multi-way valve 73 and the first multi-way valve 71, use seawater as the displacement fluid, and allow the displacement fluid to flow out of the liquid storage tank 2, through the pipeline L4, the third circulation pump 93, the third multi-way valve 73, the pipeline L5, the second multi-way valve 72 and the pipeline L7 to the ion concentration online monitor 5 and the particle size analyzer 6, and use the ion concentration online monitor 5 and the particle size analyzer 6 to measure the ion concentration C of the displacement fluid before displacement. 20 and the cumulative distribution of solid phase particle size D 10 (including the test results of D90), after the measurement is completed, the connection between the liquid storage tank 2 and the detection system is disconnected, and the displacement fluid is discharged from the device through the fourth multi-way valve 74 and the fifth multi-way valve 75;

[0151] The core in the second core holder 4 is used as an experimental core (simulating a carbonate reservoir), and the core permeability K0 of the experimental core before displacement is measured using clean water. If the experimental core is a standard core, the core permeability K0 before displacement is known.

[0152] 2. Adjust the second multi-way valve 72 and the third multi-way valve 73 to open the connection between the liquid storage tank 2 and the second core holder 4, and use the displacement fluid to displace the experimental core at a displacement pressure of 30-100 PV. After the displacement is completed, disconnect the connection between the liquid storage tank 2 and the core holder where the experimental core is located;

[0153] Using the second core holder 4 to measure the multi-point pressure corresponding to at least one displacement flow rate during or at the end of the displacement, the pressure measurement positions include the core head end, the core middle end, and the core end;

[0154] The ion concentration C1 and the cumulative distribution of solid phase particle size D1 after the displacement are measured using an ion concentration online monitor 5 and a particle size analyzer 6 (at least two cumulative displacement flow rates; as the displacement flow rate increases, D90 in the cumulative distribution of solid phase particle size after displacement should be observed to first increase and then decrease), and the test results of D1 including D90 are recorded. The total displacement flow rate of the displacement fluid is also recorded. The pressure difference between the inlet and outlet of the second core holder 4 is measured using a pressure sensor.

[0155] 3. Using the ion concentration C of the displacement fluid before displacement 10 , the ion concentration C1 after displacement alone is used to calculate the ion concentration change ΔC, and the calculation formula is:

[0156] ΔC=C1-C0,

[0157] Where: C0=C 10 .

[0158] Ions with concentration changes less than 0 are considered to be scaling ions within the core. Ions with large absolute ΔC values ​​indicate a high degree of scaling, potentially causing pressure changes within the core.

[0159] 4. Compare the cumulative distribution of solid phase particle size before displacement D 10 D90 of the core, D90 of the cumulative distribution of solid phase particle size after displacement D1, and the largest D90 is selected as the minimum retained particle size inside the core;

[0160] The minimum retention particle size within the core refers to the particle size above which scaling products will be retained in the core, blocking seepage channels and causing core contamination. The cumulative displacement flow rate corresponding to this particle size can be defined as the minimum displacement flow rate for reservoir scaling contamination damage. This cycle represents the optimal displacement flow rate for implementing on-site deblocking, anti-scaling, and descaling measures.

[0161] 5. Compare the pressures at multiple points corresponding to the same displacement flow rate and select the location with the highest pressure as the location where scaling occurs.

[0162] 6. Calculate the permeability of the core after displacement:

[0163] K=ΔP×A / (Q×μ×L)

[0164] ΔP is the pressure difference between the front and rear ends of the fluid passing through the rock at the end of displacement (i.e., the absolute value of the pressure difference between the inlet and outlet of the second core holder 4), MPa; A is the cross-sectional area of ​​the fluid passing through the rock, cm 2 ; Q is the flow rate of fluid through the core per unit time, cm 3 / s; μ is the viscosity of the displacement fluid; L is the length of the core, cm.

[0165] Calculate the degree of core damage:

[0166] λ=(K0-K) / K0×100%

[0167] Where λ is the core damage degree, K is the core permeability after flooding, and K0 is the core permeability before flooding. The core damage degree λ is used to evaluate the degree of reservoir scaling caused by the water injection process.

[0168] The above process completes the evaluation of the scaling condition of carbonate reservoirs caused by injecting seawater alone into the reservoir through four aspects: changes in ion concentration, minimum retained particle size inside the core, scaling location indicated by multiple pressure points, and degree of core damage.

[0169] Example 3

[0170] This embodiment provides a method for evaluating reservoir scaling during alternating displacement water injection. The method simulates actual water injection conditions in an oil field and specifically includes the following steps:

[0171] 1. Produced wastewater was collected on-site and filtered through a filter with a pore size of 0.45 μm. A hanging plate was placed in a high-temperature autoclave, and the produced wastewater was injected into the autoclave 1. The temperature in the autoclave 1 was controlled at 60°C, the H2S partial pressure at 0.05 MPa, and the CO2 partial pressure at 0.065 MPa to maintain constant contents of the two acidic gases in the produced wastewater. Dynamic stirring was initiated to simulate the flow of produced water in the metal pipe before injection into the formation. This was maintained for one week to allow a certain degree of corrosion to occur between the acidic produced water and the hanging plate. The resulting produced wastewater was used as the acidic fluid.

[0172] 2. By adjusting the first multi-way valve 71 and the second multi-way valve 72, the connection between the high-temperature autoclave 1 and the detection system is opened, and the produced wastewater flows out of the high-temperature autoclave 1, passes through the pipeline L1, the first multi-way valve 71, the pipeline L3, the second multi-way valve 72 and the pipeline L7 in sequence to the ion concentration online monitor 5 and the particle size analyzer 6. The ion concentration C of the produced wastewater before displacement is measured by the ion concentration online monitor 5 and the particle size analyzer 6. 10 and the cumulative distribution of solid phase particle size D 10 (including the test results of D90), after the measurement is completed, the connection between the high-temperature autoclave 1 and the detection system is disconnected, and the produced wastewater is discharged from the device through the fourth multi-way valve 74 and the fifth multi-way valve 75;

[0173] 3. Filter the river water using a filter with a pore size of 0.45 μm and inject the filtered river water into liquid storage tank 2. By adjusting the third multi-way valve 73 and the second multi-way valve 72, the connection between liquid storage tank 2 and the detection system is opened. The river water is used as the displacement fluid and flows out of liquid storage tank 2 through pipeline L4, the third circulation pump 93, the third multi-way valve 73, pipeline L5, the second multi-way valve 72, and pipeline L7 to the ion concentration online monitor 5 and the particle size analyzer 6. The ion concentration C of the river water before displacement is measured using the ion concentration online monitor 5 and the particle size analyzer 6. 20 and the cumulative distribution of solid phase particle size D 20 (including the test results of D90), after the measurement is completed, the connection between the liquid storage tank 2 and the detection system is disconnected, and the river water is discharged from the device through the fourth multi-way valve 74 and the fifth multi-way valve 75;

[0174] The core in the first core holder 3 is used as an experimental core (simulating a carbonate reservoir), and the core permeability K0 of the experimental core before displacement is measured using clean water. If the experimental core is a standard core, the core permeability K0 before displacement is known.

[0175] 4. Adjust the first multi-way valve 71 and the second multi-way valve 72 to open the connection between the high-temperature and high-pressure autoclave 1 and the first core holder 3, and use the produced wastewater to displace the experimental core. After the displacement is completed, disconnect the connection between the high-temperature and high-pressure autoclave 1 and the core holder where the experimental core is located; open the connection between the liquid storage tank 2 and the core holder where the experimental core is located, and use river water to displace the experimental core. After the displacement is completed, disconnect the connection between the liquid storage tank 2 and the core holder where the experimental core is located, completing a "produced wastewater-river water" cycle. The displacement volume of produced wastewater and river water each time is 1PV. A total of 5 cycles, i.e., 10 alternating displacements, are performed, with a total displacement volume of 10PV.

[0176] During the alternating displacement process, the first core holder 3 is used to measure the multi-point pressure corresponding to different displacement flow rates. The pressure measurement positions include the core head, the middle of the core, and the core end.

[0177] Use the detection system to measure the ion concentration C1 after the last alternating displacement, and the cumulative distribution of solid phase particle size D1 in the Nth cycle (corresponding to at least two cumulative displacement flow rates; as the displacement flow rate increases, it should be observed that D90 in the cumulative distribution of solid phase particle size after displacement first increases and then decreases). D1 includes the test results of D90;

[0178] After the alternating displacement is completed, the total displacement flow rate a of the produced wastewater and the total displacement flow rate b of the river water are recorded, and the pressure difference between the inlet and outlet ends of the first core holder 3 is measured using a pressure sensor;

[0179] 5. Using the ion concentration C of the produced wastewater before displacement 10 , ion concentration of river water before displacement C 20 , the ratio of the total displacement flow of produced sewage to the total displacement flow of river water a / b, and the ion concentration C1 after alternating displacement to calculate the ion concentration change ΔC, the calculation formula is:

[0180] ΔC=C1-C0,

[0181] Where: C0=(C 10 ×a+C 20 ×b) / (a+b).

[0182] The results are shown in Table 1:

[0183] Table 1 Ion concentrations before and after displacement

[0184]

[0185] It can be seen that, with the exception of carbonate, magnesium, iron, and hydroxide, the ion concentration changes for all other ions are less than 0, indicating that scaling of these ions occurs within the core. For ions with large absolute ΔC values, this indicates a high degree of scaling, potentially leading to pressure changes within the core. Table 1 shows that during the aforementioned alternating flooding process, calcium sulfate, magnesium sulfate, iron carbonate, and iron oxide precipitates, as well as crystals of inorganic salts such as sodium chloride and potassium chloride, were formed within the core.

[0186] 6. Use the solid phase particle size distribution D of the produced wastewater before displacement 10 , Solid phase particle size distribution of river water before displacement D 20 , the total displacement flow of produced wastewater, the total displacement flow of river water, the solid phase particle size distribution D1 after alternating displacement, and the minimum retained particle size D inside the core are calculated as:

[0187] D=max{(D90)0,(D90) N}; (D90)0 is D90 before displacement, (D90) N is the D90 after displacement measured by performing N cycles of alternating displacement, where N is a natural number greater than or equal to 1 (in this embodiment, N is 2, 4, or 5);

[0188] (D90)0=((D90) 10 ×a+(D90) 20 ×b) / (a+b);

[0189] Among them, (D90) 10 D90 is the particle size before acidic fluid displacement, obtained based on the cumulative distribution of solid phase particle size before acidic fluid displacement; (D90) 20 is the D90 particle size before displacement by the displacement fluid, obtained based on the cumulative distribution of solid phase particle size before displacement by the displacement fluid; the ratio of a to b is equal to the ratio of the total displacement flow rate of the acidic fluid during the alternating displacement process to the total displacement flow rate of the displacing fluid during the alternating displacement process.

[0190] The minimum retention particle size within the core refers to the particle size above which scaling products will be retained in the core, blocking seepage channels and causing core contamination. The cumulative displacement flow rate corresponding to this particle size can be defined as the minimum displacement flow rate for reservoir scaling contamination damage. This cycle represents the optimal displacement flow rate for implementing on-site deblocking, anti-scaling, and descaling measures.

[0191] See Table 2 for the results.

[0192] Table 2 Particle size distribution before and after displacement

[0193]

[0194] After five cycles of alternating displacement injection, totaling 10PV, the pre-displacement particle size distribution ranged from 0.15 to 1.05μm, with a D90 of 0.7μm. Comparing the particle size distribution after 4, 8, and 10PV of alternating displacement, it can be seen that with increasing displacement volume, the particle size distribution range widened, and D90 also increased from 0.75μm (after 4PV) to 1.05μm (after 8PV), indicating that the solid phase particle size of scaling continued to increase. However, after 10PV of displacement, D90 was found to be 0.9μm, indicating that as the particle size of scaling products increased, they became trapped within the core, forming a blockage and thus causing a decrease in D90. The maximum D90 can be defined as the minimum retained particle size within the core. Scaling products larger than this size will remain in the core, blocking the core seepage channel and causing core contamination. The cumulative displacement flow corresponding to the maximum D90 is 8PV, so the optimal cycle of on-site anti-scaling or descaling measures is 1 time / 8PV (PV here is the pore volume of the reservoir water flooding).

[0195] 7. The multi-point pressures corresponding to different displacement flow rates during the alternating displacement process are shown in Table 3.

[0196] Table 3 Multi-point pressure records

[0197] <![CDATA[P1]]> <![CDATA[P2]]> <![CDATA[P3]]> ΔP Displacement of 4PV 0.1 0.16 0.04 0.8 Displacement 8PV 0.4 0.6 0.02 1 Displacement 10PV 0.57 0.84 0.03 1.5

[0198] P1 is the pressure at the head end of the core, P2 is the pressure in the middle, P3 is the pressure at the end, and ΔP is the pressure difference between the inlet end and the outlet end of the first core holder.

[0199] As can be seen from Table 3, the pressure in the middle of the core is the highest, indicating that reservoir blockage pollution mainly occurs in the middle of the reservoir. As the displacement amount increases, the displacement pressure increases.

[0200] 8. Calculate the permeability of the core after displacement:

[0201] K=ΔP×A / (Q×μ×L)

[0202] ΔP is the pressure difference between the front and rear ends of the fluid passing through the rock at the end of displacement (i.e., the absolute value of the pressure difference between the inlet and outlet of the first core holder 3), MPa; A is the cross-sectional area of ​​the fluid passing through the rock, cm 2 ; Q is the flow rate of fluid through the core per unit time, cm 3 / s; μ is the viscosity of the fluid (the fluid used in the last displacement); L is the length of the core, cm.

[0203] Calculate the degree of core damage:

[0204] λ=(K0-K) / K0×100%

[0205] Among them, λ is the degree of core damage, K is the core permeability after displacement, and K0 is the core permeability before displacement. The results are shown in Table 4:

[0206] Table 4 Reservoir permeability changes at different displacement flow rates

[0207]

[0208] Table 4 shows that the core's initial permeability was 83 mD. When the displacement was 4 PV, the permeability dropped to 69.8 mD, a 15.9% decrease. When the displacement increased to 8 PV, the permeability dropped to 53.5, a 35.5% decrease. And when the displacement reached 10 PV, the permeability dropped by 45.5%. Therefore, the greater the displacement, the more severe the core damage. This suggests that during the alternating displacement process, scale continuously formed in the core, blocking the core ducts, leading to a decrease in permeability and increasing core damage.

[0209] The above process completed the evaluation of the scaling condition of carbonate reservoirs using the mixed injection process of produced wastewater and river water through four aspects: ion concentration changes, minimum retained particle size inside the core, scaling location indicated by multiple pressure points, and degree of core damage.

[0210] Example 4

[0211] This embodiment provides a method for evaluating reservoir scaling during alternating displacement water injection. The method simulates the alternating injection process of a residual acid system and seawater, and simulates the process of seawater injection after an in-situ acidification and augmentation process. The method specifically includes the following steps:

[0212] 1. Prepare 1000 ml of 5% HCl system, take 20 kg of on-site core, soak for more than 2 hours until the acid salt reaction stops, and make the residual acid system.

[0213] A hanging plate was set in the high-temperature and high-pressure autoclave 1, and the residual acid system was filtered using a filter with a pore size of 0.45 μm. The filtered residual acid system was then injected into the high-temperature and high-pressure autoclave 1. The temperature in the high-temperature and high-pressure autoclave 1 was controlled to 60° C. and no pressure was applied. Dynamic stirring was started to simulate the flow process of the residual acid system through the water injection string before injection into the formation. The stirring was maintained for one week to allow a certain degree of corrosion to occur between the acidic produced water and the hanging plate, thereby obtaining the residual acid system as the acidic fluid.

[0214] 2. By adjusting the first multi-way valve 71 and the second multi-way valve 72, the connection between the high-temperature autoclave 1 and the detection system is opened, and the ion concentration C of the acidic fluid before displacement is measured using the ion concentration online monitor 5 and the particle size analyzer 6. 10 and the cumulative distribution of solid phase particle size D 10 (including the test results of D90), after the measurement is completed, disconnect the connection between the high-temperature autoclave 1 and the detection system, and the residual acid system discharge device;

[0215] 3. Filter the seawater using a filter with a pore size of 0.45 μm and inject the filtered seawater into the liquid storage tank 2. By adjusting the third multi-way valve 73 and the second multi-way valve 72, the connection between the liquid storage tank 2 and the detection system is opened, and the seawater is used as the displacement fluid to flow out of the liquid storage tank 2. Then, the ion concentration online monitor 5 and the particle size analyzer 6 are used to measure the seawater to obtain the ion concentration C of the displacement fluid before displacement. 20 and the cumulative distribution of solid phase particle size D 20 (including the test results of D90), after the measurement is completed, the connection between the liquid storage tank 2 and the detection system is disconnected, and the displacement fluid is discharged from the device through the fourth multi-way valve 74 and the fifth multi-way valve 75;

[0216] The core in the first core holder 3 is used as an experimental core (simulating a carbonate reservoir), and the core permeability K0 of the experimental core before displacement is measured using clean water.

[0217] 4. Regulate the third multi-way valve 73 and the second multi-way valve 72 to open the connection between the liquid storage tank 2 and the core holder where the experimental core is located, and use seawater to displace the experimental core. After the displacement is completed, disconnect the connection between the liquid storage tank 2 and the core holder where the experimental core is located. Regulate the first multi-way valve 71 and the second multi-way valve 72 to open the connection between the high-temperature and high-pressure autoclave 1 and the first core holder 3, and use the residual acid system to displace the experimental core. After the displacement is completed, disconnect the connection between the high-temperature and high-pressure autoclave 1 and the core holder where the experimental core is located. Complete one "seawater-residual acid system" cycle, with the seawater and residual acid system displacing 2PV each time. Perform a total of 5 cycles, i.e., 10 alternating displacements, with a total displacement volume of 20PV.

[0218] The first core holder 3 is used to measure the multi-point pressure corresponding to different displacement flow rates during the alternating displacement process. The pressure measurement positions include the core head, the middle of the core, and the core end.

[0219] Use the detection system to measure the ion concentration C1 after the last alternating displacement, the cumulative distribution of solid phase particle size D1 after the Nth cycle displacement (corresponding to at least two cumulative displacement flow rates; as the displacement flow rate increases, it should be observed that D90 in the cumulative distribution of solid phase particle size after displacement first increases and then decreases). D1 includes the test results of D90;

[0220] After the alternating displacement is completed, record the total displacement flow rate a of the residual acid system, the total displacement flow rate b of the seawater, and the pressure difference between the inlet and outlet of the first core holder 3;

[0221] 5. Using the ion concentration C of the residual acid system before displacement 10 , the ion concentration of seawater before displacement C 20, the total displacement flow of the residual acid system, the total displacement flow of seawater, and the ion concentration C1 after alternating displacement to calculate the ion concentration change ΔC. The calculation formula is:

[0222] ΔC=C1-C0,

[0223] Where: C0=(C 10 ×a+C 20 ×b) / (a+b). The ratio of a to b is equal to the ratio of the total displacement flow of the residual acid system during the alternating displacement process to the total displacement flow of seawater during the alternating displacement process.

[0224] The results are shown in Table 5:

[0225] Table 5 Ion concentrations before and after displacement

[0226]

[0227] It can be seen that the concentrations of anions and cations changed significantly after the displacement, indicating that the residual acid system is significantly incompatible with seawater, which easily leads to the formation of inorganic scale. Table 5 lists the changes in the concentrations of the main anions and cations. Based on the analysis of the anion and cation types, it is believed that Fe(OH)3, CaSO4, MgCO3, and BaSO4 precipitates were formed during the alternating displacement process.

[0228] 6. Using the solid phase particle size distribution D of the residual acid system before displacement 10 , solid phase particle size distribution of seawater before displacement D 20 The total displacement flow of the residual acid system and the total displacement flow of seawater can be used to calculate the cumulative distribution of solid phase particle size D0 before alternating displacement; the largest D90 among the D90 of the cumulative distribution of solid phase particle size D0 before alternating displacement and the cumulative distribution of solid phase particle size D1 after alternating displacement at different cumulative displacement flow rates is taken as the minimum retained particle size D inside the core:

[0229] D=max{(D90)0,(D90) N}; (D90)0 is D90 before displacement, (D90) N is the D90 after displacement measured by performing N cycles of alternating displacement, where N is a natural number greater than or equal to 1 (in this embodiment, N is 2, 3, and 4 respectively);

[0230] (D90)0=((D90) 10 ×a+(D90) 20 ×b) / (a+b);

[0231] Among them, (D90) 10 D90 is the particle size before acidic fluid displacement, obtained based on the cumulative distribution of solid phase particle size before acidic fluid displacement; (D90) 20is the D90 particle size before displacement by the displacement fluid, obtained based on the cumulative distribution of solid phase particle size before displacement by the displacement fluid; the ratio of a to b is equal to the ratio of the total displacement flow rate of the acidic fluid during the alternating displacement process to the total displacement flow rate of the displacing fluid during the alternating displacement process.

[0232] See Table 6 for the results.

[0233] Table 6 Particle size distribution before and after displacement

[0234]

[0235] After five rounds of alternating injection, a total displacement volume of 20 PV was achieved. The particle size distribution before displacement was 0.10-1.5 μm, with a D90 of 0.9 μm. Comparing the particle size distribution after 8, 12, and 16 PV of alternating displacement, it can be seen that with increasing displacement volume, the particle size distribution range widens, and D90 also increases from 1.1 μm (after 8 PV of displacement) to 1.3 μm (after 12 PV of displacement), indicating that the solid phase particle size formed by scaling continues to increase. However, after 16 PV of displacement, D90 was found to be 0.9 μm, indicating that as the particle size of scaling products increases, they will be retained in the core, forming a blockage, which will cause a decrease in D90. The maximum D90 value can be defined as the minimum retained particle size within the core. Scaling products larger than this particle size will be retained in the core, blocking the core seepage channel and causing core contamination. The cumulative displacement flow corresponding to the maximum D90 is 12PV, so the optimal cycle of on-site anti-scaling or descaling measures is 1 time / 12PV (PV here is the pore volume of the reservoir water flooding).

[0236] 7. The multi-point pressures corresponding to different displacement flow rates during the alternating displacement process are shown in Table 7.

[0237] Table 7 Multi-point pressure records

[0238] <![CDATA[P1,MPa]]> <![CDATA[P2,MPa]]> <![CDATA[P3,MPa]]> ΔP, MPa Displacement 8PV 0.08 0.10 0.11 0.03 Displacement 12PV 0.2 0.29 0.37 0.17 Displacement 16PV 0.28 0.53 0.34 0.25

[0239] P1 is the pressure at the head end of the core, P2 is the pressure in the middle, P3 is the pressure at the end, and ΔP is the pressure difference between the inlet end of the first core holder 3 and the outlet pipe.

[0240] As displacement volume increases, pressure at all points increases, indicating scaling throughout the core, not just at the core end. As alternating displacement increases, pressure at all points increases, indicating that increasing scaling leads to a more pronounced decrease in core permeability. The highest pressure is found in the center of the core, indicating the most severe reservoir blockage and scaling there.

[0241] 8. Calculate the permeability of the core after displacement:

[0242] K=ΔP×A / (Q×μ×L)

[0243] ΔP is the pressure difference between the front and rear ends of the fluid passing through the rock at the end of displacement (i.e., the absolute value of the pressure difference between the inlet and outlet of the first core holder 3), MPa; A is the cross-sectional area of ​​the fluid passing through the rock, cm 2 ; Q is the flow rate of fluid through the core per unit time, cm 3 / s; μ is the viscosity of the fluid (the fluid used in the last displacement); L is the length of the core, cm.

[0244] Calculate the degree of core damage: λ = (K0-K) / K0×100%

[0245] Among them, λ is the degree of core damage, K is the core permeability after displacement, and K0 is the core permeability before displacement. The results are shown in Table 8:

[0246] Table 8 Core permeability changes

[0247]

[0248] It can be seen from Table 8 that with the increase of displacement volume, the core permeability gradually decreases. When the displacement volume reaches 16PV, the core permeability decreases from 58.9mD to 41.55mD, and the core damage degree is 29.46%.

[0249] The above process completed the evaluation of the scaling condition of carbonate reservoirs by alternating injection of residual acid system and seawater (simulating acidification and post-seawater injection process) through four aspects: ion concentration change, minimum retained particle size inside the core, scaling location indicated by multiple pressure points, and degree of core damage.

Claims

1. A method for evaluating reservoir scaling during water injection, the method comprising: S1. Obtaining the ion concentration and the cumulative distribution of the solid phase particle size of the experimental fluid before displacement; the experimental fluid includes an acidic fluid and / or a displacement fluid; S2. Obtain the core permeability before experimental core flooding; The experimental core is displaced with the experimental fluid to obtain multi-point pressures of the experimental core during and / or after the displacement, to obtain a cumulative distribution of solid phase particle sizes after displacement corresponding to at least two cumulative displacement flow rates, to obtain the core permeability of the experimental core during and / or after the displacement, and to record it as the core permeability after displacement; and the fluid discharged from the experimental core after the displacement is tested to obtain the ion concentration after displacement; S3. Obtaining a change in ion concentration based on the ion concentration of the experimental fluid before and after displacement; The minimum retained particle size inside the core is obtained based on the cumulative distribution of solid phase particle size before and after displacement of the experimental fluid; Obtain the scaling location based on the multi-point pressure of the test core during and / or after the flooding; The degree of core damage is obtained based on the core permeability before and after flooding; Complete reservoir scaling evaluation during water injection; Wherein, the change in ion concentration is the difference between the ion concentration before displacement and the ion concentration after displacement, and ions with an ion concentration change less than 0 are regarded as scaling ions; The method for determining the location of reservoir scaling is to compare the pressures at multiple points in the experimental core corresponding to the same displacement flow rate and select the location with the highest pressure as the location of scaling.

2. The evaluation method according to claim 1, wherein The evaluation method further includes filtering the experimental fluid before S1.

3. The evaluation method according to claim 1, wherein: When the experimental fluid includes an acidic fluid, the evaluation method further includes: S0, using the acidic fluid to corrode the metal product to perform a simulated corrosion process, and using the acidic fluid after the simulated corrosion process as the experimental fluid.

4. The evaluation method according to claim 3, wherein: S0 includes filtering the acidic fluid first, and then using the filtered acidic fluid to simulate the corrosion process.

5. The evaluation method according to claim 1, wherein: When the test fluid includes acidic fluid and displacement fluid: S1 includes obtaining the ion concentration and solid phase particle size cumulative distribution of the acidic fluid and the displacement fluid before displacement; The process of displacing the experimental core with the experimental fluid in S2 includes: alternately displacing the same experimental core with the acidic fluid and the displacement fluid.

6. The evaluation method according to claim 5, wherein: The acidic fluid includes acidic produced wastewater and / or residual acid system after pickling operation.

7. The evaluation method according to claim 6, wherein: When the acidic fluid is a residual acid system after pickling operation, the process of alternating displacement in S2 includes: cyclically displacing the experimental core in the order of displacement fluid-acidic fluid; When the acidic fluid is acidic produced water, the alternating displacement process in S2 includes: cyclically displacing the experimental core in the order of acidic fluid-displacing fluid or displacing fluid-acidic fluid.

8. The evaluation method according to claim 5, wherein: When S2 is an alternating displacement process, the ion concentration before displacement is a weighted average of the ion concentration before displacement of the acidic fluid and the ion concentration before displacement of the displacing fluid, wherein the weighting coefficient is determined according to the total displacement flow of the acidic fluid and the total displacement flow of the displacing fluid in the alternating displacement process.

9. The evaluation method according to claim 8, wherein: When S2 is an alternating displacement process, the calculation method for the change in ion concentration is: Ion concentration change = C1-C0, Where: C0=(C 10 ×a+C 20 ×b) / (a+b); C0 is the ion concentration before displacement, C1 is the ion concentration after displacement, and C 10 is the ion concentration before displacement of acidic fluid, C 20 is the ion concentration of the displacement fluid before displacement, C0, C1, C 10 、C 20 The unit is mg / L; the ratio of a to b is equal to the ratio of the total displacement flow of the acidic fluid during the alternating displacement process to the total displacement flow of the displacing fluid during the alternating displacement process.

10. The evaluation method according to any one of claims 1 to 4 and 6, wherein: The D90 particle size is obtained based on the cumulative distribution of solid phase particle size. The D90 particle size is the particle size corresponding to the cumulative distribution frequency of the particle size number reaching 90%. The minimum retained particle size inside the core is determined based on the D90 before displacement and the D90 after displacement.

11. The evaluation method according to claim 10, wherein: The minimum retained particle size inside the core is the largest D90 particle size between the D90 particle size before displacement and the D90 particle size after displacement.

12. The evaluation method according to claim 11, wherein: The cumulative displacement flow rate corresponding to the D90 particle size before displacement is 0. Among all the D90 particle sizes obtained in S1 and S2, as the cumulative displacement flow rate increases, the D90 particle size corresponding to each cumulative displacement flow rate first increases and then decreases.

13. The evaluation method according to claim 12, wherein: The cumulative displacement flow rate corresponding to the minimum retained particle size inside the core is the minimum displacement flow rate for reservoir scaling pollution damage.

14. The evaluation method according to claim 5, wherein: The D90 particle size is obtained based on the cumulative distribution of solid phase particle size. The D90 particle size is the particle size corresponding to the cumulative distribution frequency of the particle size number reaching 90%. The minimum retained particle size inside the core is determined based on the D90 before displacement and the D90 after displacement.

15. The evaluation method according to claim 14, wherein: The minimum retained particle size inside the core is the largest D90 particle size between the D90 particle size before displacement and the D90 particle size after displacement.

16. The evaluation method according to claim 15, wherein: The cumulative displacement flow rate corresponding to the D90 particle size before displacement is 0. Among all the D90 particle sizes obtained in S1 and S2, as the cumulative displacement flow rate increases, the D90 particle size corresponding to each cumulative displacement flow rate first increases and then decreases.

17. The evaluation method according to claim 16, wherein: The cumulative displacement flow rate corresponding to the minimum retained particle size inside the core is the minimum displacement flow rate for reservoir scaling pollution damage.

18. The evaluation method according to claim 14, wherein: When S2 is an alternating displacement process, the cumulative distribution of the solid phase particle size before displacement is the weighted average of the cumulative distribution of the solid phase particle size before displacement of the acidic fluid and the cumulative distribution of the solid phase particle size before displacement of the displacing fluid, and the weighting coefficient is determined according to the total displacement flow of the acidic fluid and the total displacement flow of the displacing fluid in the alternating displacement process.

19. The evaluation method according to claim 18, wherein: When S2 is an alternating displacement process, the calculation formula for the minimum retained particle size D inside the core is: D=max{(D90)0,(D90) N } Where, (D90)0 is the D90 particle size before displacement, (D90) N is the D90 particle size after displacement measured after N cycles of alternating displacement, where N is a natural number greater than or equal to 1; (D90)0=((D90) 10 ×a+(D90) 20 ×b) / (a+b); (D90) 10 、(D90) 20 are the D90 particle sizes of the acidic fluid and the displacement fluid before displacement, respectively. The ratio of a to b is equal to the ratio of the total displacement flow of the acidic fluid during the alternating displacement process to the total displacement flow of the displacement fluid during the alternating displacement process.

20. The evaluation method according to claim 1, wherein: The calculation method of the core damage degree is: λ=(K0-K) / K0×100% Where λ is the core damage degree, K is the core permeability after displacement, and K0 is the core permeability before displacement.

21. Application of the evaluation method according to any one of claims 1 to 20 in evaluating reservoir scaling during carbonate rock water injection.

22. A reservoir scaling evaluation device during water injection, the evaluation device being used to implement the evaluation method according to any one of claims 1 to 20, the evaluation device comprising: Fluid containers, core holding equipment, and detection systems; The core holding device includes a core holder having a pressure measuring hole; The detection system includes an ion concentration online monitor and a particle size analyzer that are connected to each other; The fluid container includes a high-temperature autoclave and a liquid storage tank, wherein the high-temperature autoclave is used to contain acidic fluid, and the liquid storage tank is used to contain displacement fluid; The outlet of the high-temperature and high-pressure reactor is connected to the inlet of the core clamping device and the inlet of the detection system respectively; the outlet of the liquid storage tank is connected to the inlet of the core clamping device and the inlet of the detection system respectively.

23. The evaluation device according to claim 22, wherein: The core clamping device includes a first core clamp and a second core clamp, the inlet of the first core clamp is connected to the outlet of the high-temperature and high-pressure autoclave, the inlet of the second core clamp is connected to the outlet of the liquid storage tank, and the outlets of the first core clamp and the second core clamp are respectively connected to the inlet of the detection system.

24. The evaluation device according to claim 23, wherein: The evaluation device includes a first multi-way valve, a second multi-way valve and a third multi-way valve; The first multi-way valve is provided in a connecting pipeline between the high-temperature and high-pressure autoclave and the first core holder, and the first multi-way valve is also connected to the second multi-way valve; The third multi-way valve is provided in the connecting pipeline between the liquid storage tank and the second core holder, and the third multi-way valve is also connected to the second multi-way valve; The second multi-way valve is connected to the first multi-way valve, the detection system, and the third multi-way valve respectively.

25. The evaluation device according to claim 24, wherein The evaluation device further includes a fourth multi-way valve, which is respectively connected to the outlet of the first core holder, the outlet of the second core holder, and the inlet of the detection system.

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