Reservoir scaling evaluation method in water injection process and application and device thereof

Abstract

The invention provides a reservoir scaling evaluation method in a water injection process and application and a device thereof. The evaluation method comprises the following steps: acquiring ion concentration and solid-phase particle size quantity cumulative distribution before experimental fluid displacement and rock core permeability before experimental rock core displacement; displacing the experimental rock core by using the experimental fluid to obtain the multi-point pressure and rock core permeability of the experimental rock core in the displacement process and / or after the displacement, the cumulative distribution of the number of the solid-phase particle sizes after the displacement corresponding to at least two cumulative displacement flows, and the ion concentration after the displacement; acquiring ion concentration change according to the ion concentration before and after displacement; according to the cumulative distribution of the solid-phase particle sizes before and after displacement, the minimum interception particle size in the rock core is obtained; according to the multi-point pressure, the scaling position condition is obtained; acquiring the damage degree of the rock core according to the rock core permeability before and after displacement; and reservoir scaling evaluation in the water injection process is completed. The invention further provides application of the evaluation method and an evaluation device.

Description

Technical Field

[0001] The 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 produced wastewater has increased. The demand for water injection has increased, so the reinjection of produced wastewater has become the main development method. However, since carbonate reservoirs contain CO2 and H2S acid gases, CO2 and H2S acid gases are dissolved in the produced wastewater, resulting in acidic produced water and high mineralization. TDS = (17-28) × 10 4 ppm, resulting in highly corrosive produced wastewater, causing serious corrosion to the water injection pipeline, and physical blockage of the reservoir by corrosion products. In addition, the hydrogen sulfide, carbon dioxide dissolved in the produced water, and the iron ions produced by corrosion react chemically with the carbonate reservoir rocks and reservoir fluids, resulting in the formation of scale or salt crystals, which leads to near-wellbore reservoir pollution, reduced injection capacity, and increased water injection pressure, which seriously affects the effectiveness of water injection development. In order to remove pollution, carbonate reservoirs are usually decontaminated by acid washing, but the residual acid system produced after acid washing enters the reservoir, causing ion concentration disturbances after the subsequent injection water and reservoir water are mixed, and potential scaling and crystallization reactions will occur, resulting in secondary pollution of the reservoir.

[0003] At present, the methods for evaluating reservoir pollution usually include conventional core displacement method and five sensitivity tests. Conventional core displacement method is to simulate the injection water of different water qualities to displace the core under the temperature and pressure environment of the reservoir, and calculate the change of core permeability according to the displacement volume and displacement pressure, so as to determine the pollution of the reservoir by the solid content, oil content and suspended matter content in the injected water. This method can effectively evaluate the degree of reservoir pollution caused by the physical blockage of the reservoir by the solid impurities in the injected water during the water injection process, but it is impossible to monitor the particle size and blockage position of the solid particles that block the core online, and it is also impossible to evaluate the pollution caused by pipe corrosion and water quality compatibility to the reservoir scaling. Five sensitivity tests are five sensitivity test methods for evaluating sandstone reservoirs to water, salt, acid, alkali and flow rate. It is a method used to evaluate the sensitivity of sandstone reservoirs to external fluids. Due to the obvious differences between the physical properties and lithology of carbonate rocks and sandstones, the five sensitivity tests cannot well evaluate the pollution characteristics of carbonate reservoirs.

[0004] In summary, the incompatibility between the injected water and the formation water, the chemical reaction between the high-salinity acidic produced water and the reservoir fluid and the reservoir rock, and the chemical reaction between the acid washing fluid and the reservoir cannot be effectively evaluated in the current core displacement test and five-sensitivity test during the carbonate rock water injection development process. However, since large-scale water injection development of large carbonate reservoirs and the reinjection of high-salinity acidic produced water have become the main development mode of carbonate rocks, it is of great guiding significance to establish a scaling pollution evaluation method during the carbonate reservoir water injection process, clarify the chemical mechanism of the reservoir during the water injection process, and accurately evaluate the permeability changes caused by reservoir scaling on the reservoir, which is of great guiding significance for water injection development. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is 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 the cumulative distribution of the solid phase particle size of the experimental fluid before displacement (the cumulative distribution of the solid phase particle size is the percentage of the solid phase 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 displacement; displace the experimental core with the experimental fluid, obtain the multi-point pressure of the experimental core during and / or after the displacement (i.e., the pressure at different positions of the experimental core), obtain the cumulative distribution of the solid phase particle size after displacement corresponding to at least two cumulative displacement flow rates, obtain the core permeability of the experimental core during and / or after the displacement, and record it as the core permeability after displacement;

[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 according to the ion concentration of the experimental fluid before displacement and the ion concentration after displacement;

[0011] According to the cumulative distribution of solid phase particle size before and after displacement of the experimental fluid, the minimum interception particle size inside the core is obtained;

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

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

[0014] Complete reservoir scaling evaluation during waterflooding.

[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 the field construction, and measure the parameter changes during and after the displacement; S3 is to analyze the data collected by S1 and S2, evaluate the scaling 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 core damage degree, and simulate the scaling inside the reservoir during and after the fluid injection.

[0016] In the above evaluation method, the experimental fluid is filtered before entering the fluid container. That is, the above evaluation method includes: filtering the experimental fluid before S1 (filtering the experimental fluid and then injecting the filtered experimental fluid into the fluid container.) The filtering process can remove solid particles carried by the experimental fluid itself, such as oil, mud, sand, impurities and insoluble suspended matter, to avoid affecting the evaluation results. In some specific embodiments, the pore size of the filter used in the filtering process can be 0.45μm.

[0017] According to a specific embodiment of the present invention, the acidic fluid may include acidic produced wastewater with dissolved acidic gas and / or residual acid system obtained after pickling operation, etc. The produced wastewater may be acidic high-salt produced wastewater, such as on-site produced wastewater, indoor simulated produced water, etc. During the on-site construction process, the acidic fluid contains 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, and scale will be generated, increasing the solid content in the water. The above changes will lead to scaling pollution of the reservoir.

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

[0019] In some specific embodiments, the simulated corrosion process can be carried out in a high-temperature autoclave. Before the simulated corrosion process is carried out, the above step S0 may further include: calculating the partial pressure value of the acidic gas in the acidic fluid according to the concentration of the acidic gas dissolved in the on-site acidic fluid, introducing the acidic gas into the acidic fluid of the high-temperature autoclave according to the partial pressure value, and keeping the pressure in the autoclave unchanged during the corrosion process. In some specific embodiments, nitrogen can be injected into the high-temperature autoclave to adjust the total pressure in the autoclave, and the temperature and pressure in the autoclave can be controlled by the temperature and pressure control equipment connected to the high-temperature autoclave to keep the concentration of the acidic gas in the acidic fluid constant.

[0020] According to a specific embodiment of the present invention, the displacement fluid can be used to simulate the scale contamination degree of different types of injection fluids on the reservoir. In some specific embodiments, the displacement fluid can include one or a combination of two or more of river water, sea water, and formation water. In some specific embodiments, the above-mentioned displacement fluid can be used after deoxygenation (for example, injected into a fluid storage tank after deoxygenation).

[0021] According to a specific embodiment of the present invention, the above evaluation method can be used to simulate the scaling of a reservoir using a single fluid, that is, using an acidic fluid or a displacement fluid to displace the experimental core. At this time, S1 may include obtaining the ion concentration and the cumulative distribution of the solid phase particle size of the acidic fluid or the displacement fluid before displacement; the process of S2 may include using the acidic fluid or the displacement fluid to displace an experimental core alone, and obtaining the ion concentration, the cumulative distribution of the solid phase particle size, and the core permeability after the single displacement.

[0022] According to a specific embodiment of the present invention, the above evaluation method can be used to simulate the scaling of a reservoir using a mixed fluid. At this time, S1 includes detecting the ion concentration and the cumulative distribution of the solid phase particle size of the acidic fluid and the displacement fluid before displacement; S2 uses the experimental fluid to displace the experimental core, including: using the acidic fluid and the displacement fluid to alternately displace the same experimental core. The number of alternations of the acidic fluid and the displacement fluid can be determined according to 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 the acidic produced water and the displacement fluid, and the alternating displacement process may include: cyclically displacing the experimental core in the order of acidic fluid-displacing fluid or displacing fluid-acidic fluid.

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

[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 utilizes acidic fluid and displacing fluid as a mixed fluid to alternately displace the same experimental core, the ion concentration before displacement is the weighted average of the pre-displacement ion concentration of the acidic fluid and the pre-displacement ion concentration of the displacing fluid, wherein the weighting coefficient is determined based on the total displacement flow of the acidic fluid and the total displacement flow of the displacing 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 of the acidic fluid before displacement, 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 as that of b, 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 is subjected to 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 carried out in an alternating manner of "acidic fluid-displacing fluid", the ion concentration after displacement is obtained by measuring the ion concentration of the displacing fluid of the last displacement; if the displacement is carried out in an alternating manner of "displacing fluid-acidic fluid", the ion concentration after displacement is obtained by measuring the ion concentration of the acidic fluid of the last displacement.

[0033] According to a specific embodiment of the present invention, a method for evaluating reservoir scaling based on ion concentration changes may be: ions with ion concentration changes less than 0 are regarded as scaling ions. Ion concentration changes less than 0 correspond to a decrease in the content of corresponding ions in the fluid discharged after displacement, indicating that such ions in the fluid remain in the experimental core to form scale, and therefore ions with ion concentration changes less than 0 are regarded as scaling ions.

[0034] According to a specific embodiment of the present invention, the above ion concentration change can also be used to evaluate the compatibility between two or more fluids. For example, if two or more fluids are alternately displaced in the experimental core, the calculated ion concentration changes of most anions and cations are less than 0, which may be due to the easy generation of inorganic scaling after mixing different fluids, indicating that the fluids are obviously incompatible.

[0035] According to a specific embodiment of the present invention, the above-mentioned evaluation method may include obtaining D90 according to the cumulative distribution of solid phase particle size, wherein D90 is the particle size corresponding to the cumulative distribution frequency of particle size reaching 90%; the minimum interception particle size inside the core is determined according to D90 before displacement and D90 after displacement. In some specific embodiments, the minimum interception 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, in the process of S2 data collection, 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 interception 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 rate. The cumulative displacement flow rate corresponding to the minimum interception particle size is m. When the cumulative displacement flow rate increases from 0 to m, the fluid used for displacement and the core, or the fluid used for displacement (such as acidic fluid and displacement fluid and rock in the process of alternating displacement) will form scale, and the scale growth will cause 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 the accumulation of scaling. At this time, the solid phase of large particle size is blocked in the core, 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 rate 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 interception particle size.

[0037] According to a specific embodiment of the present invention, the cumulative displacement flow rate m corresponding to the minimum interception particle size can be used as the minimum displacement flow rate for reservoir scaling pollution damage, which is the optimal flow rate for a single construction in anti-scaling measures or descaling measures. Injecting a fluid with a flow rate of m into the reservoir can prevent scaling in the reservoir and clogging the core. Injecting a fluid with a flow rate greater than m will cause the fluid to cause scaling pollution to 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 the 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 rate of the acidic fluid and the total displacement flow rate 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] Where D90 is the particle size corresponding to the cumulative distribution frequency of the particle size reaching 90%, (D90)0 is the D90 before displacement, (D90) N The D90 after displacement is measured after 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 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 of the acidic fluid during the alternating displacement process to the total displacement flow 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 of the minimum retained particle size inside the core can take all integers from 1 to n, and n is the total number of cycles, so as to obtain more D90 particle size data after displacement and improve the accuracy of judging 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 the solid phase particle size after displacement is the cumulative distribution of the solid phase particle size 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 pressure, middle pressure and end pressure of the core.

[0047] According to a specific embodiment of the present invention, the method of using multi-point pressure to determine the location of reservoir scaling is: 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 pressure refers to 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 5PV respectively, and the total cumulative flow rate is 10PV, then the displacement flow rate corresponding to the multi-point pressure measured at this time is 10PV. In some specific embodiments, the multi-point pressure of one displacement flow rate can be measured as needed, or the multi-point pressure of more than two displacement flows can be measured.

[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] Among them, λ is the core damage degree, K is the core permeability after displacement, and K0 is the core permeability before displacement. According to the core damage degree calculated above, the degree 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 may be:

[0052] K=ΔP×A / (Q×μ×L)

[0053] ΔP is the pressure difference between the two ends of the fluid passing through the rock (i.e. the absolute value of the pressure difference between the inlet and outlet 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 passing 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 clamping device comprises a core clamp having a pressure measuring hole;

[0058] The detection system includes an ion concentration online monitor and a particle size analyzer 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 contain 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 contain the acidic fluid, and the liquid storage tank is used to contain 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 and high pressure 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-salt 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 of the reservoir during the water injection process. In some specific embodiments, hanging plates can be hung in the high temperature and high pressure autoclave. Furthermore, the high temperature and high pressure autoclave can also be connected to a temperature and pressure control device 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, and the above parameters of the acidic fluid can be detected using an online ion concentration monitor and a 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, thereby simulating the injection water temperature at the site. The injection water temperature is generally 10-30°C lower than the formation temperature, and accordingly, the temperature of the displacement fluid in the fluid storage tank may 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 measuring holes, and each core clamp is respectively provided with 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 liquid storage tank, and the outlet of the first core clamp and the outlet of the second core clamp are respectively connected to the detection system.

[0066] According to a specific embodiment of the present invention, the core clamping device (the first core clamp and the second core clamp) is a core clamp with more than two pressure measuring holes, which can continuously monitor the pressure of multiple positions of the core in real time. The pressure change at each position in the core clamp can reflect the location where scaling blockage occurs and judge the depth of scaling pollution.

[0067] In some specific embodiments, the core holder with the pressure measuring hole may be connected to a pressure control device, and the pressure control device may 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 respectively connected to pressure sensors for detecting the pressure difference between the two ends of the core holder.

[0069] In the above specific implementation scheme, 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 one of the inlets 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 one of the inlets 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 relationship between the high-temperature autoclave and the first core clamp, and the first multi-way valve and the second multi-way valve can jointly control the connection relationship between the high-temperature autoclave and the detection system; the third multi-way valve can directly control the connection relationship between the liquid storage tank and the second core clamp, and the second multi-way valve and the third multi-way valve can jointly control the connection relationship 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 relationship between the high-temperature autoclave and the second core clamp, and the first multi-way valve, the second multi-way valve, and the third multi-way valve can jointly control the connection relationship between the liquid storage tank and the first core clamp.

[0073] According to a specific embodiment of the present invention, 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, that is, the first multi-way valve is respectively connected to the outlet of the high temperature and high pressure 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 the first multi-way valve may 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 the third multi-way valve 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 exhaust device for exhausting fluids in 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 ion concentration online monitor and a particle size analyzer. Among them, the ion concentration online monitor can detect the concentration of different types of ions in the experimental fluid. The particle size analyzer can detect the cumulative distribution of the solid phase particle size of the experimental fluid, and can also detect the particle size distribution frequency.

[0078] According to the above specific embodiments, 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 and high pressure 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 online ion concentration 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 respectively 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;

[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 the detection system respectively.

[0088] According to a specific embodiment of the present invention, the evaluation device may further include a fourth multi-way valve, which belongs to a connection system, and the fourth multi-way valve 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 through 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 may 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 may be a four-way valve; alternatively, a fifth multi-way valve may 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 advection pump, which is arranged 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 more than two 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 achieve connection between the above-mentioned devices in the system. The pipeline may specifically be 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 an application of the above evaluation method in evaluating reservoir scaling during carbonate rock water injection. During the development of carbonate rocks, the produced wastewater obtained is generally high-salinity, acidic produced wastewater with dissolved acidic gases. The above evaluation method provided by the present invention is suitable for evaluating the scaling of high-salinity, acidic produced wastewater injected into the reservoir.

[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 scaling pollution degree caused by different water injection sources and water injection after acidification operation in the process of reservoir water injection development, and grasp the water quality changes in the displacement process through ion concentration and particle size analysis, and obtain the reservoir scaling law and scaling influencing factors. The evaluation method can simulate the dynamic scaling process and the static scaling process, and can be applied to the scaling pollution evaluation in the process of carbonate oil reservoir water injection development. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 This is a schematic diagram of the structure of the evaluation device of Example 1.

[0098] Explanation of symbols: high-temperature and high-pressure autoclave 1, stirring rod 11, metal hanging plate 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, purposes 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 construed as limiting the applicable scope of the present invention.

[0100] In the description of the invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on 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 the 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 stipulated 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 high temperature and high pressure autoclave 1 is used to contain the acidic fluid. A metal hanging sheet 12 is hung in the high temperature and high pressure autoclave 1. The corrosive fluid and the hanging sheet corrode in the autoclave to simulate the composition of the acidic produced water injected into the formation on site or the residual acid system produced after the pickling operation. A stirring rod 11 can also be provided in the high temperature and high pressure autoclave to stir the acidic fluid during the corrosion process to simulate the 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 clamp 3 and a second core holder, which are used to accommodate and fix the core. The first core clamp 3 and the second core holder are both core clamps with pressure measuring holes, which can detect the pressure at various positions of the core, that is, multi-point pressure, in real time. In this embodiment, the core clamp with pressure measuring holes is provided with pressure measuring holes at both ends and the middle of the core, respectively, and the pressure at both ends (the first end and the tail end) and the middle of the core can be measured.

[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 ion concentration online monitor 5 and a particle size analyzer 6. The ion concentration online monitor 5 can realize online rapid and continuous monitoring of key anion and cation concentrations, and the particle size analyzer 6 can monitor the particle size distribution in the fluid (including the cumulative distribution of the number of solid particle sizes and the distribution frequency of each particle size range). The ion concentration online monitor 5 and the particle size analyzer 6 are connected to each other.

[0110] The temperature and pressure control system can be regarded as 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-measurement 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 multi-way valve 71, the second multi-way valve 72, and the third multi-way valve 73 are used to coordinately control the connection relationship 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 the liquid flowing out of 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 realize the connection between 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 the pipeline L1, connected to the second multi-way valve 72 through the pipeline L3, and connected to the inlet of the first core holder 3 through the 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 through the pipeline L5, and is connected to the ion concentration online monitor 5 through the pipeline L7. In addition, the second multi-way valve 72 is also connected to the emptying device for emptying 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, and 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, for providing 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 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 in a water injection process using acidic fluid displacement alone, the method comprising the following steps:

[0129] 1. Take produced sewage on site, and calculate the partial pressure of acidic gas hydrogen sulfide to be 0.6MPa based on the content of hydrogen sulfide in produced sewage of 120ppm. Introduce N2 and H2S, maintain the total pressure at 4MPa, and the H2S partial pressure at 0.6MPa. Filter the produced sewage with a filter with a pore size of 0.45μm.

[0130] A hanging piece is set in the high-temperature and high-pressure autoclave 1, and then the filtered produced wastewater is injected. The temperature in the high-temperature and high-pressure autoclave 1 is controlled to be 60°C and the H2S partial pressure is 0.6MPa to maintain the dissolved hydrogen sulfide content in the solution system; dynamic stirring is turned on to simulate the flow process of produced water in the metal pipe column before being injected into the formation. The process is maintained for one week to allow a certain degree of corrosion to occur between the acidic produced water and the hanging piece, 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, and flows 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, and 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 sewage 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, use the produced wastewater to displace the experimental core, and disconnect the connection between the high-temperature autoclave 1 and the first core holder 3 after the displacement is completed;

[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, the middle of the core, and the core end;

[0135] The ion concentration C1 after the displacement is completed, the cumulative distribution of the solid phase particle size D1 (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 the solid phase particle size after displacement first increases and then decreases), and the test results of D1 including D90 are measured by using an ion concentration online detector 5 and a particle size analyzer 6, and the total displacement flow rate of the produced wastewater is recorded. The pressure difference of the pipeline where the inlet and outlet ends of the first core holder 3 are located is measured by a pressure sensor;

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

[0137] ΔC=C1-C0,

[0138] Where: C0=C 10 .

[0139] For ions whose concentration changes are all less than 0, they are judged to be ions that will cause scaling inside the core. For ions with large absolute values ​​of ΔC, it means that the scaling degree of these ions is large, which may cause pressure changes inside the core.

[0140] 5. Compare the cumulative distribution of solid phase particle size before displacement D 10 The D90 of the cumulative distribution of solid phase particle size after displacement, D1, and the largest D90 is selected as the minimum interception particle size inside the core; the minimum interception particle size inside the core means that scaling products larger than this particle size will be retained in the core and block the seepage channel, causing core pollution. The cumulative displacement flow corresponding to this particle size can be defined as the minimum displacement flow for reservoir scaling pollution damage. This cycle is the optimal displacement flow for on-site implementation of unblocking measures, anti-scaling measures, and scale removal 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 passing 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] Among them, λ is the core damage degree, K is the core permeability after displacement, and K0 is the core permeability before displacement. The core damage degree λ is used to evaluate the reservoir scaling degree caused by the water injection process.

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

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

[0150] 1. 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; 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 the seawater as the displacement fluid, and make the displacement fluid 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 result of D90), after the measurement, 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. Regulate the second multi-way valve 72 and the third multi-way valve 73, open the connection between the liquid storage tank 2 and the second core holder 4, use the displacement fluid to displace the experimental core, displace 30-100 PV, and 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, the middle of the core, and the core end;

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

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

[0156] ΔC=C1-C0,

[0157] Where: C0=C 10 .

[0158] For ions whose concentration changes are all less than 0, they are judged to be ions that will cause scaling inside the core. For ions with large absolute values ​​of ΔC, it means that the scaling degree of these ions is large, which may cause pressure changes inside the core.

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

[0160] The minimum interception particle size inside the core means that scaling products larger than this particle size will be retained in the core and block the seepage channel, causing core pollution. The cumulative displacement flow corresponding to this particle size can be defined as the minimum displacement flow for reservoir scaling pollution damage. This cycle is the optimal displacement flow for on-site implementation of unblocking measures, anti-scaling measures, and scale removal 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 ends 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 passing 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] Among them, λ is the core damage degree, K is the core permeability after displacement, and K0 is the core permeability before displacement. The core damage degree λ is used to evaluate the reservoir scaling degree caused by the water injection process.

[0168] The above process completed the evaluation of the scaling of carbonate reservoirs by injecting seawater alone into the reservoir through four aspects: change in ion concentration, minimum retained particle size inside the core, scaling location indicated by multi-point pressure, and degree of core damage.

[0169] Example 3

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

[0171] 1. Take produced sewage on site, filter it with a filter with a pore size of 0.45 μm, set a hanging plate in the high-temperature autoclave, and then inject the produced sewage into the high-temperature autoclave 1, control the temperature in the high-temperature autoclave 1 to 60°C, the H2S partial pressure to 0.05MPa, and the CO2 partial pressure to 0.065MPa to keep the content of the two acidic gases in the produced sewage constant; start dynamic stirring to simulate the flow process of produced water in the metal pipe column before injection into the formation, keep it for one week to cause a certain degree of corrosion between the acidic produced water and the hanging plate, and the obtained produced sewage is 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, and 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 sewage 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 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 river water is used as the displacement fluid to make the river water 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 the ion concentration C of the river water before displacement is measured by 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 result of D90), after the measurement, 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. Regulate the first multi-way valve 71 and the second multi-way valve 72, open the connection between the high-temperature and high-pressure autoclave 1 and the first core holder 3, use the produced wastewater to displace the experimental core, and disconnect the connection between the high-temperature and high-pressure autoclave 1 and the core holder where the experimental core is located after the displacement is completed; open the connection between the liquid storage tank 2 and the core holder where the experimental core is located, use river water to displace the experimental core, and disconnect the connection between the liquid storage tank 2 and the core holder where the experimental core is located after the displacement is completed, completing a "produced wastewater-river water" cycle, the displacement volume of produced wastewater and river water each time is 1PV, and a total of 5 cycles, i.e. 10 alternating displacements, 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 pressures corresponding to different displacement flow rates, and 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 the 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 the 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 sewage 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 by a pressure sensor;

[0179] 5. Using the ion concentration of the produced wastewater before displacement C 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 concentration before and after displacement

[0184]

[0185] It can be seen that, except for carbonate, magnesium, iron and hydroxide, the changes in the ion concentrations of other ions are less than 0, and other ions will scale inside the core. For ions with a large absolute value of ΔC, it means that the scaling degree of these ions is large, which may cause pressure changes inside the core. According to Table 1, during the above-mentioned alternating displacement process, calcium sulfate, magnesium sulfate, iron carbonate, iron oxide precipitation and inorganic salt crystals such as sodium chloride and potassium chloride are present inside 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 sewage, the total displacement flow of river water, the solid phase particle size distribution D1 after alternating displacement, and the minimum interception particle size D inside the core are calculated as:

[0187] D=max{(D90)0,(D90) N}; (D90)0 is the D90 before displacement, (D90) N The D90 after displacement is 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 particle size before acidic fluid displacement, obtained based on the cumulative distribution of solid phase particle size before acidic fluid displacement; (D90) 20 It is the D90 particle size before displacement by the displacing fluid, obtained according to the cumulative distribution of solid phase particle size before displacement by the displacing fluid; 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.

[0190] The minimum interception particle size inside the core means that scaling products larger than this particle size will be retained in the core and block the seepage channel, causing core pollution. The cumulative displacement flow corresponding to this particle size can be defined as the minimum displacement flow for reservoir scaling pollution damage. This cycle is the optimal displacement flow for on-site implementation of unblocking measures, anti-scaling measures, and scale removal measures.

[0191] See Table 2 for the results.

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

[0193]

[0194] After 5 rounds of alternate displacement injection, the displacement volume totaled 10PV, and the particle size distribution before displacement was 0.15-1.05μm, D90 = 0.7μm; by comparing the particle size distribution after alternate displacement of 4PV, 8PV, and 10PV, it can be seen that with the increase in displacement, the particle size distribution range increases, and D90 also increases from 0.75μm (after displacement of 4PV) to 1.05μm (after displacement of 8PV), indicating that the solid phase particle size formed by scaling continues to increase; but after displacement of 10PV, D90 = 0.9μm was found, indicating that as the particle size of scaling products increases, they will be retained inside the core, forming blockages, thereby causing D90 to decrease. The maximum value of D90 can be defined as the minimum interception particle size inside the core. Scaling products larger than this particle size will be retained in the core, blocking the core seepage channel and causing core pollution. 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 affected by 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 Displacing 4PV 0.1 0.16 0.04 0.8 Displacing 8PV 0.4 0.6 0.02 1 Displacement 10PV 0.57 0.84 0.03 1.5

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

[0199] It can be seen from Table 3 that 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 volume 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 passing 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] As can be seen from Table 4, the initial permeability of the core is 83mD. When the displacement is 4PV, the permeability drops to 69.8mD, a decrease of 15.9%; when the displacement increases to 8PV, the permeability of the core drops to 53.5, a decrease of 35.5%; and when the displacement reaches 10PV, the permeability drops by 45.5%. Therefore, the greater the displacement, the deeper the damage to the core. This shows that during the alternating displacement process, scale is constantly generated in the core, which continuously blocks the core roar, resulting in a decrease in permeability and an increase in the degree of core damage.

[0209] The above process completed the evaluation of the scaling condition of carbonate reservoirs using the mixed injection technology of produced wastewater and river water through four aspects: changes in ion concentration, minimum retained particle size inside the core, scaling location indicated by multi-point pressure, 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 process of alternating injection of residual acid system and seawater, and simulates the process of injecting seawater after the on-site acidification and augmentation process. Specifically, the method 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 a residual acid system.

[0213] A hanging sheet is arranged in the high temperature and high pressure autoclave 1, and the residual acid system is filtered by a filter with a pore size of 0.45 μm, and then the filtered residual acid system is injected into the high temperature and high pressure autoclave 1, and the temperature in the high temperature and high pressure autoclave 1 is controlled to be 60° C. without adding pressure; dynamic stirring is started to simulate the flow process of the residual acid system through the water injection string before being injected into the formation, and the process is maintained for one week to allow a certain degree of corrosion to occur between the acidic produced water and the hanging sheet, so as to obtain 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 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, 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 with a filter having 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 make the seawater 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 result of D90), after the measurement, 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, open the connection between the liquid storage tank 2 and the core holder where the experimental core is located, use seawater to displace the experimental core, and disconnect the connection between the liquid storage tank 2 and the core holder where the experimental core is located after the displacement is completed; regulate the first multi-way valve 71 and the second multi-way valve 72, open the connection between the high-temperature and high-pressure autoclave 1 and the first core holder 3, use the residual acid system to displace the experimental core, and disconnect the connection between the high-temperature and high-pressure autoclave 1 and the core holder where the experimental core is located after the displacement is completed; complete a cycle of "seawater-residual acid system", the displacement volume of seawater and residual acid system each time is 2PV, and a total of 5 cycles are performed, that is, 10 alternating displacements, with a total displacement volume of 20PV;

[0218] The first core holder 3 is used to measure the multi-point pressures corresponding to different displacement flow rates during the alternating displacement process, and 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, measure the cumulative distribution D1 of the solid phase particle size 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 the solid phase particle size after displacement first increases and then decreases), and D1 includes the test results of D90;

[0220] After the alternating displacement is completed, 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 are recorded;

[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 concentration before and after displacement

[0226]

[0227] It can be seen that the concentrations of anions and cations have changed significantly after displacement, indicating that the residual acid system is obviously incompatible with seawater and easily causes the formation of inorganic scale. Table 5 lists the changes in the concentrations of major anions and cations. According to the analysis of the types of anions and cations, it is believed that Fe(OH)3, CaSO4, MgCO3, BaSO4 and other precipitates are 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, the cumulative distribution of the solid phase particle size before the alternating displacement D0 can be calculated; the largest D90 of the cumulative distribution of the solid phase particle size before the alternating displacement D0 and the cumulative distribution of the solid phase particle size after the alternating displacement of different cumulative displacement flow rates D1 is taken as the minimum interception particle size D inside the core:

[0229] D=max{(D90)0,(D90) N}; (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 (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 particle size before acidic fluid displacement, obtained based on the cumulative distribution of solid phase particle size before acidic fluid displacement; (D90) 20It is the D90 particle size before displacement by the displacing fluid, obtained according to the cumulative distribution of solid phase particle size before displacement by the displacing fluid; 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.

[0232] See Table 6 for the results.

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

[0234]

[0235] After 5 rounds of alternate injection, the displacement volume totaled 20 PV, the particle size distribution before displacement was 0.10-1.5um, and D90 = 0.9 μm; by comparing the particle size distribution after alternate displacement of 8 PV, 12 PV, and 16 PV, it can be seen that with the increase in displacement, the particle size distribution range increases, and D90 also increases from 1.1 μm (after displacement of 8 PV) to 1.3 μm (after displacement of 12 PV), indicating that the solid phase particle size formed by scaling continues to increase; but after displacement of 16 PV, D90 = 0.9 μm was found, indicating that as the particle size of scaling products increases, they will be retained inside the core, forming blockages, thereby causing D90 to decrease. The maximum value of D90 can be defined as the minimum interception particle size inside the core. Scaling products larger than this particle size will be retained in the core, blocking the core seepage channel and causing core pollution. 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 affected by 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 Displacing 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 head end pressure of the core, P2 is the middle pressure, P3 is the end pressure, and ΔP is the pressure difference between the inlet end of the first core holder 3 and the pipeline where the outlet pipe is located.

[0240] It can be seen that as the displacement volume increases, the pressure at each point increases, indicating that scaling occurs in the entire core section, not just at the core port. As the alternating displacement volume increases, the pressure at each point increases, indicating that the scaling volume increases and the permeability of the core decreases more significantly. Among them, the pressure in the middle of the core is the highest, indicating that the reservoir blockage and scaling in the middle of the core are the most serious.

[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 passing 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: change in ion concentration, minimum retained particle size inside the core, scaling location indicated by multi-point pressure, 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, obtaining the core permeability before experimental core flooding; The experimental core is displaced with the experimental fluid to obtain the multi-point pressure of the experimental core during and / or after the displacement, to obtain the cumulative distribution of the solid phase particle size after the 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 the displacement; and to detect the fluid discharged from the experimental core after the displacement to obtain the ion concentration after the displacement; S3, obtaining a change in ion concentration according to the ion concentration of the experimental fluid before displacement and the ion concentration after displacement; According to the cumulative distribution of solid phase particle size before and after displacement of the experimental fluid, the minimum interception particle size inside the core is obtained; Obtain the scaling location based on the multi-point pressure of the test core during and / or after the displacement; The degree of core damage is obtained based on the core permeability before and after displacement; Complete reservoir scaling evaluation during waterflooding.

2. The evaluation method according to claim 1, wherein: The evaluation method further comprises filtering the test fluid before S1.

3. The evaluation method according to claim 1 or 2, 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; Preferably, S0 includes filtering the acidic fluid first, and then using the filtered acidic fluid to simulate the corrosion process.

4. The evaluation method according to claim 1, wherein: When the experimental fluid includes an acidic fluid and a displacement fluid; S1 includes obtaining the ion concentration and the cumulative distribution of the solid phase particle size 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 acid fluid and the displacement fluid.

5. The evaluation method according to claim 4, wherein: The acidic fluid includes acidic produced wastewater and / or residual acid system after pickling operation.

6. The evaluation method according to claim 5, 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 process of alternating displacement in S2 includes: cyclically displacing the experimental core in the order of acidic fluid-displacing fluid or displacing fluid-acidic fluid.

7. The evaluation method according to any one of claims 1 to 6, 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.

8. The evaluation method according to claim 7, 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 displacement fluid, wherein the weighting coefficient is determined according to the total displacement flow of the acidic fluid and the total displacement flow of the displacement fluid in the alternating displacement process; Preferably, when S2 is an alternating displacement process, the calculation method of the ion concentration change 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, C 10 is the ion concentration of the acidic fluid before displacement, 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.

9. The evaluation method according to any one of claims 1 to 6, wherein: The D90 particle size is obtained according to the cumulative distribution of solid phase particle size, and the D90 particle size is the particle size corresponding to the cumulative distribution frequency of the particle size number reaching 90%; the minimum interception particle size inside the core is determined according to the D90 before displacement and the D90 after displacement; Preferably, 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; Preferably, the cumulative displacement flow rate corresponding to the D90 particle size before displacement is 0, and 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; Preferably, the cumulative displacement flow corresponding to the minimum interception particle size inside the core is the minimum displacement flow for reservoir scaling pollution damage.

10. The evaluation method according to claim 9, wherein: When S2 is an alternating displacement process, the cumulative distribution of the solid phase particle size before displacement is a 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 displacement fluid, and the weighting coefficient is determined according to the total displacement flow of the acidic fluid and the total displacement flow of the displacement fluid in the alternating displacement process; Preferably, 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.

11. The evaluation method according to claim 1, wherein: The method for determining the location where scaling occurs in the reservoir 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 location where scaling occurs.

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

13. Application of the evaluation method according to any one of claims 1 to 12 in evaluating reservoir scaling during carbonate rock water injection.

14. A reservoir scaling evaluation device during water injection, the evaluation device comprising: Fluid containers, core holding equipment, detection systems; The core clamping device comprises a core clamp having a pressure measuring hole; The detection system includes an ion concentration online monitor and a particle size analyzer connected to each other; The fluid container comprises a high temperature and high pressure autoclave and a liquid storage tank, wherein the high temperature and high pressure autoclave is used to contain an acidic fluid, and the liquid storage tank is used to contain a displacement fluid; The outlet of the high-temperature and high-pressure reactor is respectively connected to the inlet of the core clamping device and the inlet of the detection system; the outlet of the liquid storage tank is respectively connected to the inlet of the core clamping device and the inlet of the detection system.

15. The evaluation device according to claim 14, 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.

16. The evaluation device according to claim 15, 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 arranged in the connecting pipeline between the liquid storage tank and the second core clamp, 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.

17. The evaluation device according to claim 16, wherein: The evaluation device further comprises a fourth multi-way valve, and the fourth multi-way valve is respectively connected to an outlet of the first core holder, an outlet of the second core holder, and an inlet of a detection system.

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