A method and system for evaluating the contamination of a casing

Abstract

The application provides a casing pollution evaluation method and system. The casing pollution evaluation method comprises the following steps: step 1, obtaining a first feature before drilling fluid circulation; step 2, performing drilling fluid circulation on the casing for a first preset time length; step 3, obtaining a second feature after drilling fluid circulation; and step 4, evaluating the pollution degree in the casing according to the first feature and the second feature. After the drilling fluid flows through the casing, residues are left on the inner wall of the casing, thereby forming pollution to the inner wall of the casing. The pollution degree of the casing is evaluated. Different drilling fluids can be replaced to evaluate the pollution degrees of the casing caused by different drilling fluids. Therefore, more real and accurate data information can be obtained as a reference. When applied to actual operations, the method can provide a reference for the selection of drilling fluids and cleaning fluids.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum drilling engineering, and particularly relates to a casing pollution evaluation method and system. BACKGROUND

[0002] In the petroleum drilling engineering, well cementation is an important link in the process of drilling and completion operation. Specifically, well cementation is the operation of lowering casing into the well and injecting cement into the annular space between the wellbore and the casing. The purpose is to protect and support the casing of the oil and gas well, and to seal the oil, gas and water formations.

[0003] Because drilling fluid is usually introduced into the casing during drilling, drilling fluid remains in the casing after well cementation, and the casing usually needs to be cleaned. However, the environment at the construction site is complex, and after drilling, it is not possible to determine the degree of pollution of the casing by the drilling fluid, so that the casing cannot be efficiently cleaned. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a casing pollution evaluation method and system to overcome the shortcomings of the prior art.

[0005] The technical solution of the present application to solve the above technical problem is as follows: a casing pollution evaluation method, comprising: step 1, obtaining a first feature before drilling fluid circulation;

[0006] Step 2, circulating drilling fluid in the casing for a first predetermined time;

[0007] Step 3, obtaining a second feature after drilling fluid circulation;

[0008] Step 4, evaluating the degree of pollution in the casing according to the first feature and the second feature.

[0009] The beneficial effects of the technical solution of the present application are: when evaluating the degree of pollution, the inner wall of the casing is polluted by the drilling fluid, specifically, the drilling fluid remains on the inner wall of the casing after flowing through the casing, thereby forming pollution of the inner wall of the casing. The degree of pollution of the casing is evaluated. Different drilling fluids can be replaced to evaluate the degree of pollution of the casing by different drilling fluids. The actual working conditions of the casing can be simulated, thereby reducing the error of the simulation results, and thus more accurate data information can be obtained as a reference. In practical operation, it can be used as a reference for the selection of drilling fluid and cleaning fluid, and efficient cleaning can be achieved.

[0010] Further, the step 4 further comprises: step 5, obtaining a third feature before cleaning fluid circulation;

[0011] Step 6, circulating cleaning fluid in the casing for a second predetermined time;

[0012] Step 7, obtaining a fourth feature after the cleaning fluid is circulated;

[0013] Step 8, evaluating the cleaning effect in the casing according to the third feature and the fourth feature.

[0014] The beneficial effects of the further technical solutions are: when the cleaning effect needs to be evaluated, the circulating cleaning fluid can be provided to the casing, and the residual drilling fluid on the inner wall of the casing can be removed to achieve the purpose of cleaning the casing. By replacing different cleaning fluids, the cleaning effect of different cleaning fluids on the contaminated casing can be evaluated.

[0015] Further, the first feature is a first particle size distribution graph, and the second feature is a second particle size distribution graph.

[0016] The step 4 includes: step 411, determining a first particle size median before the drilling fluid is circulated according to the first particle size distribution graph, and determining a second particle size median after the drilling fluid is circulated according to the second particle size distribution graph.

[0017] Step 412, calculating a contamination value in the casing according to the first particle size median before the drilling fluid is circulated and the second particle size median after the drilling fluid is circulated.

[0018] Step 413, evaluating the contamination degree in the casing according to the contamination value in the casing.

[0019] The third feature is a third particle size distribution graph, and the fourth feature is a fourth particle size distribution graph.

[0020] The step 8 includes: step 811, determining a third particle size median before the cleaning fluid is circulated according to the third particle size distribution graph, and determining a fourth particle size median after the cleaning fluid is circulated according to the fourth particle size distribution graph.

[0021] Step 812, calculating a cleaning effect value in the casing according to the third particle size median before the cleaning fluid is circulated and the fourth particle size median after the cleaning fluid is circulated.

[0022] Step 813, evaluating the cleaning effect in the casing according to the cleaning effect value in the casing.

[0023] The beneficial effect of the further technical scheme is that, in the drilling fluid circulation process, after the casing is contaminated, part of the components in the drilling fluid remains on the inner wall of the casing, and the particle size distribution of the drilling fluid in the circulation process changes compared with the particle size distribution of the original drilling fluid. The contamination degree in the casing can be judged by the particle size distribution change of the drilling fluid before and after contamination. Similarly, the particle size distribution of the cleaning fluid before and after cleaning also changes after the cleaning fluid is used to clean the casing, and thus the cleaning effect can be judged by the particle size distribution change of the cleaning fluid before and after cleaning the casing. The particle size distribution graph before and after the drilling fluid circulation is tested, and the particle size median before and after the drilling fluid circulation is determined according to the particle size distribution graph before and after the drilling fluid circulation. Similarly, the particle size distribution graph before and after the cleaning fluid circulation is tested, and the particle size median before and after the cleaning fluid circulation is determined according to the particle size distribution graph before and after the cleaning fluid circulation.

[0024] Further, the contamination value in the casing is calculated by the following formula:

[0025] η1=(D 50 a-D 50 b)÷D 50 a

[0026] Wherein, η1 is the contamination value in the casing, D 50 a is the first particle size median before the drilling fluid circulation, D 50 b is the second particle size median after the drilling fluid circulation;

[0027] The cleaning effect value in the casing is calculated by the following formula:

[0028] η2=(D 50 d-D 50 c)÷D 50 c

[0029] Wherein, η2 is the cleaning effect value in the casing, D 50 c is the third particle size median before the cleaning fluid circulation, D 50 d is the fourth particle size median after the cleaning fluid circulation.

[0030] The beneficial effect of the further technical scheme is that the contamination value in the casing is used for contamination degree evaluation; the greater the contamination value, the heavier the contamination degree, and the smaller the contamination value, the lighter the contamination degree. Similarly, the cleaning effect value is used for cleaning effect evaluation; the greater the cleaning effect value, the better the cleaning effect, and the smaller the cleaning effect value, the worse the cleaning effect.

[0031] Further, the first feature is a first weight value of the casing, and the second feature is a second weight value of the casing;

[0032] The step 4 comprises: step 421, acquiring first preset experimental data;

[0033] Step 422, calculating a first weight change value of the casing according to the first weight value and the second weight value;

[0034] Step 423, evaluating the contamination degree in the casing according to the first weight change value of the casing and the first preset experimental data;

[0035] The third feature is a third weight value of the casing, and the fourth feature is a fourth weight value of the casing;

[0036] The step 8 comprises:

[0037] Step 822, calculating a second weight change value of the casing according to the third weight value and the fourth weight value;

[0038] Step 823, evaluating the cleaning effect in the casing according to the second weight change value of the casing and the second preset experimental data.

[0039] The beneficial effects of the above further technical solutions are: after the casing is contaminated, the inner wall of the casing is left with drilling fluid, so the weight of the casing will change compared with the weight when the casing is not contaminated. Therefore, the contamination degree in the casing can also be judged by the weight change of the casing before and after contamination. Similarly, the weight of the casing before and after cleaning will also change, so the cleaning effect can be judged by the weight change of the casing before and after cleaning. Specifically, after the drilling fluid circulation is completed, the casing can be taken out for weighing to obtain the weight of the contaminated casing, and then compared with the weight of the casing before contamination. Thus, by comparing and analyzing the weight change of the casing with the preset experimental data, the contamination degree of the casing can be evaluated.

[0040] Further, the second feature is a first pollution grid number after the drilling fluid circulation,

[0041] The step 4 comprises:

[0042] Step 432, evaluating the contamination degree in the casing according to the ratio of the pollution grid number to the total number of grids;

[0043] The third feature is a second pollution grid number before the cleaning fluid circulation, and the fourth feature is a third pollution grid number after the cleaning fluid circulation,

[0044] The step 8 comprises:

[0045] Step 831, calculating a cleaning effect ratio of the difference between the second pollution grid number and the third pollution grid number to the second pollution grid number according to the second pollution grid number and the third pollution grid number.

[0046] Step 832, evaluating the cleaning effect in the sleeve according to the cleaning effect ratio.

[0047] The beneficial effect of the further technical solution is that the sleeve is provided with a detection window, the detection window is made of sapphire material and is grid divided; the detection window can be used to detect the light transmittance before and after the sleeve is contaminated and / or cleaned, and the number of contaminated grids is counted, so that the contamination degree and / or cleaning degree are evaluated based on the number of contaminated grids. During the circulation of the drilling fluid, after the sleeve is contaminated, the inner wall of the sleeve is left with the drilling fluid, and the light transmittance of the detection window after the sleeve is contaminated changes compared with the light transmittance of the detection window before the sleeve is contaminated. The contamination degree of the sleeve can be determined by the change of the light transmittance of the detection window before and after contamination. Similarly, after the sleeve is cleaned with the recycled cleaning fluid, the light transmittance of the detection window also changes before and after cleaning, so that the cleaning effect can be determined by the change of the light transmittance of the detection window before and after cleaning. The contamination degree is evaluated by the ratio of the number of contaminated grids of the detection window after the sleeve is contaminated to the total number of grids of the detection window; the greater the ratio of the number of contaminated grids of the detection window after the sleeve is contaminated to the total number of grids of the detection window, the more serious the contamination degree; the smaller the ratio of the number of contaminated grids of the detection window after the sleeve is contaminated to the total number of grids of the detection window, the less the contamination degree. The cleaning effect is evaluated by the ratio of the difference between the number of contaminated grids of the detection window before the sleeve is cleaned and the number of contaminated grids of the detection window after the sleeve is cleaned to the number of contaminated grids of the detection window before the sleeve is cleaned; the greater the ratio of the difference between the number of contaminated grids of the detection window before the sleeve is cleaned and the number of contaminated grids of the detection window after the sleeve is cleaned to the number of contaminated grids of the detection window before the sleeve is cleaned, the better the cleaning effect; the smaller the ratio of the difference between the number of contaminated grids of the detection window before the sleeve is cleaned and the number of contaminated grids of the detection window after the sleeve is cleaned to the number of contaminated grids of the detection window before the sleeve is cleaned, the worse the cleaning effect.

[0048] Further, the step 1 further comprises: obtaining a preset temperature value and a preset pressure value.

[0049] According to the preset temperature value and the preset pressure value, the temperature and the pressure inside the sleeve are controlled.

[0050] The beneficial effect of the further technical solution is that the actual temperature and the actual pressure in the well during drilling are simulated, the real working condition of the sleeve is simulated, the error of the simulation result is greatly reduced, and more real and accurate data information is obtained as a reference. When applied to actual operation, the selection of the drilling fluid and the cleaning fluid can be referenced, and efficient cleaning is realized.

[0051] Further, the application also provides a casing pollution evaluation system, comprising: a casing simulation device provided with a casing, a liquid circulating subsystem, a processor and a detection device, the detection device and the liquid circulating subsystem are connected with the casing simulation device, the processor is connected with the detection device, the detection device is used for acquiring a first feature before drilling fluid circulation; the liquid circulating subsystem is used for carrying out drilling fluid circulation on the casing for a first preset time length; the detection device is further used for acquiring a second feature after drilling fluid circulation; the processor is used for evaluating the pollution degree in the casing according to the first feature and the second feature.

[0052] The beneficial effects of the technical scheme of the application are: when the pollution degree is evaluated, the inner wall of the casing is polluted by the drilling fluid, specifically, the drilling fluid will remain on the inner wall of the casing after flowing through the casing, and then the pollution of the inner wall of the casing is formed. The pollution degree of the casing is evaluated. Then different drilling fluids can be replaced to evaluate the pollution degree of the casing caused by different drilling fluids. The real working condition of the casing can be simulated, thereby reducing the error of the simulation result, so that more real and accurate data information can be obtained as a reference. When applied to actual operation, it can be used as a reference for the selection of drilling fluid and cleaning fluid, and efficient cleaning can be realized.

[0053] Further, the detection device is further used for acquiring a third feature before cleaning fluid circulation; the liquid circulating subsystem is further used for carrying out cleaning fluid circulation on the casing for a second preset time length; the detection device is further used for acquiring a fourth feature after cleaning fluid circulation; and the processor is further used for evaluating the cleaning effect in the casing according to the third feature and the fourth feature.

[0054] The beneficial effects of the above further technical scheme are: when the cleaning effect needs to be evaluated, the circulating cleaning fluid can be provided to the casing, and the remaining drilling fluid on the inner wall of the casing can be removed by the cleaning fluid to achieve the purpose of cleaning the casing. Different cleaning fluids can be replaced to evaluate the cleaning effect of different cleaning fluids on the polluted casing.

[0055] Further, the detection device is a particle size analyzer, the particle size analyzer is connected with pipelines between the liquid circulating subsystem and the casing simulation device, the particle size analyzer is used for acquiring a first particle size distribution graph, a second particle size distribution graph, a third particle size distribution graph and a fourth particle size distribution graph; the processor is further used for determining a first particle size median value before the drilling fluid circulation according to the first particle size distribution graph, and determining a second particle size median value after the drilling fluid circulation according to the second particle size distribution graph; the processor is further used for calculating a pollution value in the casing according to the first particle size median value before the drilling fluid circulation and the second particle size median value after the drilling fluid circulation; the processor is further used for evaluating a pollution degree in the casing according to the pollution value in the casing; the processor is further used for determining a third particle size median value before the cleaning fluid circulation according to the third particle size distribution graph, and determining a fourth particle size median value after the cleaning fluid circulation according to the fourth particle size distribution graph; the processor is further used for calculating a cleaning effect value in the casing according to the third particle size median value before the cleaning fluid circulation and the fourth particle size median value after the cleaning fluid circulation; and the processor is further used for evaluating a cleaning effect in the casing according to the cleaning effect value in the casing.

[0056] Or,

[0057] The detection device is a weighing sensor, the weighing sensor is connected with the casing simulation device, the weighing sensor is used for acquiring a first weight value, a second weight value, a third weight value and a fourth weight value; the processor is further used for acquiring first preset experimental data; the processor is further used for calculating a first weight change value of the casing according to the first weight value and the second weight value; the processor is further used for evaluating a pollution degree in the casing according to the first weight change value of the casing and the first preset experimental data; the processor is further used for acquiring second preset experimental data; the processor is further used for calculating a second weight change value of the casing according to the third weight value and the fourth weight value; and the processor is further used for evaluating a cleaning effect in the casing according to the second weight change value of the casing and the second preset experimental data.

[0058] The beneficial effects of the further technical scheme are as follows: in the drilling fluid circulation process, after the casing is contaminated, part of the components in the drilling fluid remains on the inner wall of the casing, and the particle size distribution of the drilling fluid in the circulation process changes compared with the particle size distribution of the original drilling fluid. The contamination degree in the casing can be determined by the particle size distribution change of the drilling fluid before and after contamination. Similarly, the particle size distribution of the cleaning fluid before and after cleaning also changes, and thus the cleaning effect can be determined by the particle size distribution change of the cleaning fluid before and after cleaning. The particle size distribution graph before and after the drilling fluid circulation is tested, and the particle size median before and after the drilling fluid circulation is determined according to the particle size distribution graph before and after the drilling fluid circulation. Similarly, the particle size distribution graph before and after the cleaning fluid circulation is tested, and the particle size median before and after the cleaning fluid circulation is determined according to the particle size distribution graph before and after the cleaning fluid circulation. Or, after the casing is contaminated, the drilling fluid remains on the inner wall of the casing, so the weight of the casing changes compared with the weight when the casing is not contaminated. Thus, the contamination degree in the casing can also be determined by the weight change before and after contamination. Similarly, the weight before and after the casing cleaning also changes, and thus the cleaning effect can be determined by the weight change before and after the casing cleaning. Specifically, after the drilling fluid circulation is completed, the casing can be taken out for weighing to obtain the weight of the contaminated casing, and then compared with the weight of the casing before contamination, so that the contamination degree of the casing can be evaluated by comparing and analyzing the weight change of the casing with the preset test data.

[0059] The advantages of the additional aspects of the application will be, in part, apparent and, in part, apparent from the following description, or will be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 A module schematic diagram of a casing contamination evaluation system provided for an embodiment of the application is shown in the figure;

[0061] Figure 2 A structural schematic diagram of a casing contamination evaluation system provided for an embodiment of the application is shown in the figure;

[0062] Figure 3 A structural schematic diagram of another casing contamination evaluation system provided for an embodiment of the application is shown in the figure;

[0063] Figure 4 A structural schematic diagram of still another casing contamination evaluation system provided for an embodiment of the application is shown in the figure;

[0064] Figure 5 A structural schematic diagram of a casing simulation device in a casing contamination evaluation system provided for an embodiment of the application is shown in the figure;

[0065] Figure 6 A structural schematic diagram of another casing simulation device in a casing contamination evaluation system provided for an embodiment of the application is shown in the figure;

[0066] Figure 7 Structure diagram of another casing simulation device in a casing pollution evaluation system provided by an embodiment of the present application;

[0067] Figure 8 Structure diagram of a detection window in a casing pollution evaluation system provided by an embodiment of the present application;

[0068] Figure 9 Particle size distribution diagram before circulation of cleaning liquid in an embodiment of the present application;

[0069] Figure 10 Particle size distribution diagram after circulation of cleaning liquid in an embodiment of the present application;

[0070] Figure 11 Schematic flow chart of a casing pollution evaluation method provided by an embodiment of the present application.

[0071] BRIEF DESCRIPTION OF DRAWINGS 100, casing simulation device; 110, shell; 120, casing; 121, detection window; 130, weighing sensor; 200, temperature control device; 210, heating jacket; 220, temperature controller; 300, pressure control device; 310, gas storage tank; 320, pressure gauge; 330, gas guide pipe; 340, air pressure valve; 400, liquid circulation subsystem; 410, circulation pump; 420, liquid storage tank; 421, first liquid storage tank; 422, second liquid storage tank; 430, pipeline; 440, on-off valve; 450, particle size analyzer. DETAILED DESCRIPTION

[0072] The principles and features of the present application are described below in conjunction with the accompanying drawings, and the examples are only used to explain the present application and not to limit the scope of the present application.

[0073] As shown in Figure 11 , an embodiment of the present application provides a casing pollution evaluation method, comprising:

[0074] Step 1, obtaining a first feature before circulation of drilling fluid;

[0075] Step 2, circulating drilling fluid on the casing for a first preset time;

[0076] Step 3, obtaining a second feature after circulation of drilling fluid;

[0077] Step 4, evaluating the pollution degree in the casing according to the first feature and the second feature.

[0078] The beneficial effect of the technical scheme is that when the pollution degree is evaluated, the inner wall of the casing is polluted by the drilling fluid, specifically, the drilling fluid remains on the inner wall of the casing after flowing through the casing, and then the pollution of the inner wall of the casing is formed. The pollution degree of the casing is evaluated. Then, different drilling fluids can be replaced to evaluate the pollution degree of the casing caused by different drilling fluids. The real working condition of the casing can be simulated, thereby reducing the error of the simulation result, and thus more real and accurate data information can be obtained as a reference. When applied to actual operation, the selection of the drilling fluid and the cleaning fluid can be referenced, and efficient cleaning is realized.

[0079] It should be noted that the first feature, the second feature, the third feature and the fourth feature can be various apparent features changed before and after the drilling fluid circulation and before and after the cleaning fluid circulation, and features measured by different ways. The first feature, the second feature, the third feature and the fourth feature can be, but are not limited to, particle size distribution change, particle size median change, weight change and / or pollution grid number change, and the particle size distribution change, the particle size median change, the weight change and the pollution grid number change can be evaluated at the same time in multiple combinations.

[0080] Further, the step 4 comprises:

[0081] Step 5, obtaining a third feature before the cleaning fluid circulation;

[0082] Step 6, circulating the cleaning fluid in the casing for a second preset time length;

[0083] Step 7, obtaining a fourth feature after the cleaning fluid circulation;

[0084] Step 8, evaluating the cleaning effect in the casing according to the third feature and the fourth feature.

[0085] The beneficial effect of the above further technical scheme is that when the cleaning effect needs to be evaluated, the circulating cleaning fluid can be provided to the casing, and the remaining drilling fluid on the inner wall of the casing can be removed by the cleaning fluid to achieve the purpose of cleaning the casing. Different cleaning fluids can be replaced to evaluate the cleaning effect of different cleaning fluids on the polluted casing.

[0086] Further, the first feature is a first particle size distribution graph, and the second feature is a second particle size distribution graph.

[0087] The step 4 comprises:

[0088] Step 411, determining a first particle size median before the drilling fluid circulation according to the first particle size distribution graph, and determining a second particle size median after the drilling fluid circulation according to the second particle size distribution graph;

[0089] Step 412, calculating a pollution value in the casing according to the first median particle size before circulation of the drilling fluid and the second median particle size after circulation of the drilling fluid;

[0090] Step 413, evaluating the pollution degree in the casing according to the pollution value in the casing;

[0091] The third feature is a third particle size distribution graph, and the fourth feature is a fourth particle size distribution graph;

[0092] The step 8 comprises:

[0093] Step 811, determining a third median particle size before circulation of the cleaning fluid according to the third particle size distribution graph, and determining a fourth median particle size after circulation of the cleaning fluid according to the fourth particle size distribution graph;

[0094] Step 812, calculating a cleaning effect value in the casing according to the third median particle size before circulation of the cleaning fluid and the fourth median particle size after circulation of the cleaning fluid;

[0095] Step 813, evaluating the cleaning effect in the casing according to the cleaning effect value in the casing.

[0096] The beneficial effects of the above further technical solutions are: in the process of circulation of the drilling fluid, after the casing is polluted, part of components in the drilling fluid remains on the inner wall of the casing, and the particle size distribution of the drilling fluid in the circulation process changes compared with the particle size distribution of the original drilling fluid. The pollution degree in the casing can be judged by the change of the particle size distribution of the drilling fluid before and after pollution. Similarly, the particle size distribution of the cleaning fluid also changes before and after the cleaning fluid is used to clean the casing, and thus the cleaning effect can be judged by the change of the particle size distribution of the cleaning fluid before and after the casing is cleaned. The particle size distribution graphs before and after circulation of the drilling fluid are tested, and the median particle sizes before and after circulation of the drilling fluid are determined according to the particle size distribution graphs before and after circulation of the drilling fluid. Similarly, the particle size distribution graphs before and after circulation of the cleaning fluid are tested, and the median particle sizes before and after circulation of the cleaning fluid are determined according to the particle size distribution graphs before and after circulation of the cleaning fluid.

[0097] Further, the pollution value in the casing is calculated by the following formula:

[0098] η1=(D 50 a-D 50 b)÷D 50 a

[0099] Wherein, η1 is the pollution value in the casing, D 50 a is the first median particle size before circulation of the drilling fluid, and D 50 b is the second median particle size after circulation of the drilling fluid;

[0100] The cleaning effect value in the casing is calculated by the following formula:

[0101] η2 = (D 50 d - D 50 c) ÷ D 50 c

[0102] Wherein, η2 is the cleaning effect value in the casing, D 50 c is the third particle size median before the cleaning fluid circulation, D 50 d is the fourth particle size median after the cleaning fluid circulation.

[0103] The beneficial effects of the above further technical solutions are: the pollution value in the casing is used to evaluate the pollution degree; the greater the pollution value, the heavier the pollution degree, and the smaller the pollution value, the lighter the pollution degree. Similarly, the cleaning effect value is used to evaluate the cleaning effect; the greater the cleaning effect value, the better the cleaning effect, and the smaller the cleaning effect value, the worse the cleaning effect.

[0104] Further, the first feature is a first weight value of the casing, and the second feature is a second weight value of the casing.

[0105] The step 4 comprises:

[0106] Step 421, acquiring first preset experimental data;

[0107] Step 422, calculating a first weight change value of the casing according to the first weight value and the second weight value;

[0108] Step 423, evaluating the pollution degree in the casing according to the first weight change value of the casing and the first preset experimental data;

[0109] The third feature is a third weight value of the casing, and the fourth feature is a fourth weight value of the casing.

[0110] The step 8 comprises:

[0111] Step 821, acquiring second preset experimental data;

[0112] Step 822, calculating a second weight change value of the casing according to the third weight value and the fourth weight value;

[0113] Step 823, evaluating the cleaning effect in the casing according to the second weight change value of the casing and the second preset experimental data.

[0114] The beneficial effects of the further technical solutions are: since the inner wall of the casing is left with the drilling fluid after the casing is contaminated, the weight of the casing will change compared with the weight when the casing is not contaminated. Thus, the degree of contamination in the casing can also be determined by the weight change of the casing before and after contamination. Similarly, the weight of the casing will also change before and after cleaning, and thus the cleaning effect can be determined by the weight change of the casing before and after cleaning. Specifically, after the drilling fluid circulation is completed, the casing can be taken out for weighing to obtain the weight of the contaminated casing, and then compared with the weight of the casing before contamination. Thus, by comparing the weight change of the casing with the preset test data, the degree of contamination of the casing can be evaluated.

[0115] Further, the second feature is the first number of contaminated grids after the drilling fluid circulation,

[0116] The step 4 comprises:

[0117] Step 431, obtaining the total number of grids of the detection window of the casing;

[0118] Step 432, evaluating the degree of contamination in the casing according to the ratio of the number of contaminated grids to the total number of grids;

[0119] The third feature is the second number of contaminated grids before the cleaning fluid circulation, and the fourth feature is the third number of contaminated grids after the cleaning fluid circulation,

[0120] The step 8 comprises:

[0121] Step 831, calculating the cleaning effect ratio of the difference between the second number of contaminated grids and the third number of contaminated grids to the second number of contaminated grids according to the second number of contaminated grids and the third number of contaminated grids;

[0122] Step 832, evaluating the cleaning effect in the casing according to the cleaning effect ratio.

[0123] The beneficial effects of the further technical scheme are that the detection window is provided on the casing, the detection window is made of sapphire material and is grid divided, the light transmittance of the detection window is detected before and after the casing is contaminated and / or cleaned, the number of contaminated grids is counted, and the contamination degree and / or cleaning degree are evaluated based on the number of contaminated grids. During the drilling fluid circulation, the inner wall of the casing is left with the drilling fluid after the casing is contaminated, and the light transmittance of the detection window changes after the casing is contaminated compared with that before the casing is contaminated. The contamination degree of the casing can be determined by the change of the light transmittance of the detection window before and after the casing is contaminated. Similarly, the light transmittance of the detection window also changes before and after the casing is cleaned by the recycled cleaning fluid, and thus the cleaning effect can be determined by the change of the light transmittance of the detection window before and after the casing is cleaned. The contamination degree is evaluated by the ratio of the number of contaminated grids of the detection window of the casing after the casing is contaminated to the total number of grids of the detection window of the casing. The greater the ratio of the number of contaminated grids of the detection window of the casing after the casing is contaminated to the total number of grids of the detection window of the casing, the more serious the contamination degree. The smaller the ratio of the number of contaminated grids of the detection window of the casing after the casing is contaminated to the total number of grids of the detection window of the casing, the less serious the contamination degree. The cleaning effect is evaluated by the ratio of the difference between the number of contaminated grids of the detection window of the casing before the casing is cleaned and the number of contaminated grids of the detection window of the casing after the casing is cleaned to the number of contaminated grids of the detection window of the casing before the casing is cleaned. The greater the ratio of the difference between the number of contaminated grids of the detection window of the casing before the casing is cleaned and the number of contaminated grids of the detection window of the casing after the casing is cleaned to the number of contaminated grids of the detection window of the casing before the casing is cleaned, the better the cleaning effect. The smaller the ratio of the difference between the number of contaminated grids of the detection window of the casing before the casing is cleaned and the number of contaminated grids of the detection window of the casing after the casing is cleaned to the number of contaminated grids of the detection window of the casing before the casing is cleaned, the worse the cleaning effect.

[0124] Further, the step 1 further comprises:

[0125] obtaining a preset temperature value and a preset pressure value;

[0126] controlling the temperature and the pressure inside the casing according to the preset temperature value and the preset pressure value.

[0127] The beneficial effects of the further technical scheme are that the actual temperature and the actual pressure in the well during the drilling are simulated, the real working condition of the casing is simulated, the error of the simulation result is greatly reduced, and thus more real and accurate data information can be obtained as a reference. When applied to the actual operation, the selection of the drilling fluid and the cleaning fluid can be referenced, and efficient cleaning can be realized.

[0128] The casing contamination evaluation method and system provided by the present application can be used for the casing contamination and cleaning evaluation method and system.

[0129] The first aspect of the present application provides a casing contamination evaluation system, comprising a casing simulation device, a temperature control device, a pressure control device and a liquid circulation subsystem;

[0130] The casing simulation device is internally provided with a casing;

[0131] The temperature control device is arranged in the casing simulation device and used for controlling the temperature in the casing simulation device;

[0132] The pressure control device is connected with the casing simulation device and used for controlling the pressure in the casing simulation device;

[0133] The liquid circulation subsystem is connected with the casing simulation device and used for inputting circulating drilling fluid and circulating cleaning fluid into the casing;

[0134] The casing is provided with a visual detection window which is divided into grids; and / or the liquid circulation subsystem is provided with a particle size analyzer used for monitoring the particle size of the circulating drilling fluid and the circulating cleaning fluid.

[0135] In combination with the first aspect, in a possible implementation, the material of the visual detection window which is divided into grids is sapphire.

[0136] In combination with the first aspect, in a possible implementation, the casing is detachable.

[0137] In combination with the first aspect, in a possible implementation, the casing simulation device further comprises a weighing sensor, which is connected with the casing and used for detecting the weight of the casing.

[0138] In combination with the first aspect, in a possible implementation, the casing is arranged in a vertical direction, and the weighing sensor is supported below the casing or the casing is hung below the weighing sensor.

[0139] In combination with the first aspect, in a possible implementation, the liquid circulation subsystem comprises two circulating pumps and two liquid storage tanks;

[0140] The two liquid storage tanks are respectively used for storing drilling fluid and cleaning fluid;

[0141] Each of the circulating pumps is connected with the casing and one of the liquid storage tanks through a pipeline.

[0142] In combination with the first aspect, in a possible implementation, the liquid circulation subsystem comprises one circulating pump and two liquid storage tanks;

[0143] The two liquid storage tanks are respectively used for storing drilling fluid and cleaning fluid;

[0144] The circulating pump is connected with the sleeve and the two liquid storage tanks through pipelines, wherein a switch valve is arranged on the pipeline between the circulating pump and the corresponding liquid storage tank.

[0145] In combination with the first aspect, in a possible implementation, the temperature control device comprises a heating sleeve and a temperature controller, the heating sleeve is sleeved on the outer circumferential surface of the sleeve simulation device, and the temperature controller is electrically connected with the heating sleeve and used for controlling the heating temperature of the heating sleeve.

[0146] In combination with the first aspect, in a possible implementation, the pressure control device comprises a gas storage tank and a pressure gauge, the gas storage tank is connected with the sleeve simulation device through a gas guide pipe, and the pressure gauge is arranged on the gas guide pipe.

[0147] In the second aspect, the present application further provides a sleeve pollution evaluation method, which applies the sleeve pollution evaluation system provided in the first aspect.

[0148] The circulating drilling fluid is input into the sleeve, and the temperature and the pressure in the sleeve simulation device are controlled.

[0149] After the drilling fluid circulates for a first preset time length, the pollution grid number of the sleeve pollution detection window after pollution is obtained and / or the particle size median before and after the circulation of the drilling fluid is obtained, and the pollution degree is evaluated according to the pollution grid number of the sleeve pollution detection window after pollution and / or the particle size median before and after the circulation of the drilling fluid.

[0150] The circulating cleaning fluid is input into the sleeve, and the temperature and the pressure in the sleeve simulation device are controlled.

[0151] After the cleaning fluid circulates for a second preset time length, the pollution grid number of the sleeve detection window before and after cleaning is obtained and / or the particle size median before and after the circulation of the cleaning fluid is obtained, and the cleaning effect is evaluated according to the change of the pollution grid number of the sleeve detection window before and after cleaning and / or the change of the particle size median before and after the circulation of the cleaning fluid.

[0152] In combination with the second aspect, in a possible implementation, the pollution degree is evaluated according to the pollution grid number of the sleeve pollution detection window after pollution, which comprises: the pollution degree is evaluated according to the ratio of the pollution grid number of the sleeve pollution detection window after pollution to the total number of grids of the sleeve detection window.

[0153] The greater the ratio of the pollution grid number of the sleeve pollution detection window after pollution to the total number of grids of the sleeve detection window, the more serious the pollution degree; the smaller the ratio of the pollution grid number of the sleeve pollution detection window after pollution to the total number of grids of the sleeve detection window, the less serious the pollution degree.

[0154] With reference to the second aspect, in a possible implementation of the second aspect, the cleaning effect is evaluated according to a change in the number of contaminated grids of the detection window before and after the cleaning of the casing, and the evaluating the cleaning effect according to the change in the number of contaminated grids of the detection window before and after the cleaning of the casing includes: evaluating the cleaning effect according to a ratio of a difference between the number of contaminated grids of the detection window before the cleaning of the casing and the number of contaminated grids of the detection window after the cleaning of the casing to the number of contaminated grids of the detection window before the cleaning of the casing.

[0155] The greater the ratio of the difference between the number of contaminated grids of the detection window before the cleaning of the casing and the number of contaminated grids of the detection window after the cleaning of the casing to the number of contaminated grids of the detection window before the cleaning of the casing, the better the cleaning effect; the smaller the ratio of the difference between the number of contaminated grids of the detection window before the cleaning of the casing and the number of contaminated grids of the detection window after the cleaning of the casing to the number of contaminated grids of the detection window before the cleaning of the casing, the worse the cleaning effect.

[0156] With reference to the second aspect, in a possible implementation of the second aspect, the pollution degree is evaluated according to a change in the median particle size before and after the circulation of the drilling fluid, and the evaluating the pollution degree according to the change in the median particle size before and after the circulation of the drilling fluid includes: evaluating the pollution degree according to a ratio of a difference between the median particle size before the circulation of the drilling fluid and the median particle size after the circulation of the drilling fluid to the median particle size before the circulation of the drilling fluid.

[0157] The greater the ratio of the difference between the median particle size before the circulation of the drilling fluid and the median particle size after the circulation of the drilling fluid to the median particle size before the circulation of the drilling fluid, the more serious the pollution degree; the smaller the ratio of the difference between the median particle size before the circulation of the drilling fluid and the median particle size after the circulation of the drilling fluid to the median particle size before the circulation of the drilling fluid, the less serious the pollution degree.

[0158] With reference to the second aspect, in a possible implementation of the second aspect, the cleaning effect is evaluated according to a change in the median particle size before and after the circulation of the cleaning fluid, and the evaluating the cleaning effect according to the change in the median particle size before and after the circulation of the cleaning fluid includes: evaluating the cleaning effect according to a ratio of a difference between the median particle size after the circulation of the cleaning fluid and the median particle size before the circulation of the cleaning fluid to the median particle size before the circulation of the cleaning fluid.

[0159] The greater the ratio of the difference between the median particle size after the circulation of the cleaning fluid and the median particle size before the circulation of the cleaning fluid to the median particle size before the circulation of the cleaning fluid, the better the cleaning effect; the smaller the ratio of the difference between the median particle size after the circulation of the cleaning fluid and the median particle size before the circulation of the cleaning fluid to the median particle size before the circulation of the cleaning fluid, the worse the cleaning effect.

[0160] With reference to the second aspect, in a possible implementation of the second aspect, the casing is arranged along a vertical direction, a flow direction of the drilling fluid in the casing is from a lower end of the casing to an upper end of the casing, and a flow direction of the cleaning fluid is opposite to the flow direction of the drilling fluid.

[0161] With reference to the second aspect, in a possible implementation of the second aspect, the method further includes:

[0162] After the drilling fluid circulates for a first preset time length, the weight before and after the casing is polluted is acquired, and the pollution degree is evaluated according to the weight change before and after the casing is polluted.

[0163] In combination with the second aspect, in a possible implementation, the method further includes:

[0164] After the cleaning fluid circulates for a second preset time length, the weight before and after the casing is cleaned is acquired, and the cleaning effect is evaluated according to the weight change before and after the casing is cleaned.

[0165] The casing pollution evaluation method and system provided by the application, wherein the casing pollution evaluation system controls the temperature and pressure of the casing simulation device through the temperature control device and the pressure control device, thereby simulating the actual working condition, and then simulates the pollution of the drilling fluid to the casing through the liquid circulation subsystem, evaluates the pollution degree through the grid pollution condition and / or drilling fluid particle size distribution change of the grid of the visual detection window. Then, the liquid circulation subsystem simulates the cleaning of the casing by the cleaning fluid, and then evaluates the cleaning effect through the pollution grid number change and / or cleaning fluid particle size distribution change of the grid of the visual detection window. Therefore, the casing pollution evaluation system provided by the application can simulate the real working condition of the casing, thereby greatly reducing the error of the simulation result, and thus more real and accurate data information can be obtained as a reference. When applied to actual operation, it can be used as a reference for the selection of drilling fluid and cleaning fluid, and high-efficiency cleaning can be realized.

[0166] As shown in Figures 1 to 10 In addition, the application further provides a casing pollution evaluation system, comprising: a casing simulation device provided with a casing, a liquid circulation subsystem, a processor and a detection device, the detection device and the liquid circulation subsystem are connected with the casing simulation device, the processor is connected with the detection device,

[0167] The detection device is used to acquire a first feature before the drilling fluid circulates.

[0168] The liquid circulation subsystem is used to circulate the drilling fluid to the casing for a first preset time length.

[0169] The detection device is further used to acquire a second feature after the drilling fluid circulates.

[0170] The processor is used to evaluate the pollution degree in the casing according to the first feature and the second feature.

[0171] The beneficial effects of the technical scheme are as follows: when the pollution degree is evaluated, the inner wall of the casing is polluted by the drilling fluid, specifically, the drilling fluid remains on the inner wall of the casing after flowing through the casing, and then the pollution of the inner wall of the casing is formed. The pollution degree of the casing is evaluated. Then, different drilling fluids can be replaced to evaluate the pollution degrees of the casing caused by different drilling fluids. The real working conditions of the casing can be simulated, so that the error of the simulation result is reduced, and thus more real and accurate data information can be obtained as a reference. When applied to actual operation, the selection of the drilling fluid and the cleaning fluid can be referenced, and efficient cleaning is realized.

[0172] Further, the detection device is further used to obtain a third feature before the cleaning fluid circulation;

[0173] The liquid circulation subsystem is further used to circulate the cleaning fluid in the casing for a second preset time length.

[0174] The detection device is further used to obtain a fourth feature after the cleaning fluid circulation.

[0175] The processor is further used to evaluate the cleaning effect in the casing according to the third feature and the fourth feature.

[0176] The beneficial effects of the above further technical scheme are as follows: when the cleaning effect needs to be evaluated, the circulating cleaning fluid can be provided to the casing, and the remaining drilling fluid on the inner wall of the casing can be removed by the cleaning fluid, so that the casing is cleaned. Different cleaning fluids can be replaced to evaluate the cleaning effects of the polluted casing caused by different cleaning fluids.

[0177] Further, the detection device is a particle size analyzer, and the particle size analyzer is connected with the liquid circulation subsystem and the casing simulation device through a pipeline,

[0178] The particle size analyzer is used to obtain a first particle size distribution graph, a second particle size distribution graph, a third particle size distribution graph and a fourth particle size distribution graph.

[0179] The processor is further used to determine a first particle size median value before the drilling fluid circulation according to the first particle size distribution graph, and determine a second particle size median value after the drilling fluid circulation according to the second particle size distribution graph.

[0180] The processor is further used to calculate a pollution value in the casing according to the first particle size median value before the drilling fluid circulation and the second particle size median value after the drilling fluid circulation.

[0181] The processor is further used to evaluate the pollution degree in the casing according to the pollution value in the casing.

[0182] The processor is further configured to determine a third particle size median value before the cleaning liquid is circulated according to the third particle size distribution map and determine a fourth particle size median value after the cleaning liquid is circulated according to the fourth particle size distribution map;

[0183] The processor is further configured to calculate a cleaning effect value in the sleeve according to the third particle size median value before the cleaning liquid is circulated and the fourth particle size median value after the cleaning liquid is circulated;

[0184] The processor is further configured to evaluate the cleaning effect in the sleeve according to the cleaning effect value in the sleeve;

[0185] Or,

[0186] The detection device is a weighing sensor, and the weighing sensor is connected with the sleeve simulation device,

[0187] The weighing sensor is configured to obtain a first weight value, a second weight value, a third weight value and a fourth weight value.

[0188] The processor is further configured to obtain first preset experimental data.

[0189] The processor is further configured to calculate a first weight change value of the sleeve according to the first weight value and the second weight value.

[0190] The processor is further configured to evaluate the pollution degree in the sleeve according to the first weight change value of the sleeve and the first preset experimental data.

[0191] The processor is further configured to obtain second preset experimental data.

[0192] The processor is further configured to calculate a second weight change value of the sleeve according to the third weight value and the fourth weight value.

[0193] The processor is further configured to evaluate the cleaning effect in the sleeve according to the second weight change value of the sleeve and the second preset experimental data.

[0194] The beneficial effect of the further technical scheme is that in the drilling fluid circulation process, after the casing is contaminated, part of the components in the drilling fluid remains on the inner wall of the casing, and the particle size distribution of the drilling fluid in the circulation process changes compared with the particle size distribution of the original drilling fluid. The contamination degree in the casing can be judged by the particle size distribution change of the drilling fluid before and after contamination. Similarly, the particle size distribution of the cleaning fluid before and after cleaning also changes, and thus the cleaning effect can be judged by the particle size distribution change of the cleaning fluid before and after cleaning. The particle size distribution graph before and after the drilling fluid circulation is tested, and the particle size median before and after the drilling fluid circulation is determined according to the particle size distribution graph before and after the drilling fluid circulation. Similarly, the particle size distribution graph before and after the cleaning fluid circulation is tested, and the particle size median before and after the cleaning fluid circulation is determined according to the particle size distribution graph before and after the cleaning fluid circulation. Or, since the inner wall of the casing is contaminated, the drilling fluid remains on the inner wall of the casing, and thus the weight of the casing changes compared with the weight when the casing is not contaminated. Thus, the contamination degree in the casing can also be judged by the weight change before and after contamination. Similarly, the weight before and after cleaning of the casing also changes, and thus the cleaning effect can be judged by the weight change before and after cleaning of the casing. Specifically, after the drilling fluid circulation is completed, the casing can be taken out for weighing to obtain the weight of the contaminated casing, and then compared with the weight of the casing before contamination, and thus the contamination degree of the casing can be evaluated by comparing and analyzing the weight change of the casing with the preset test data.

[0195] Embodiment one

[0196] As shown in Figure 1 and Figure 2 , the embodiment provides a casing contamination evaluation system, which belongs to the technical field of petroleum drilling and production engineering. The arrows on the pipeline in the figure represent the valves.

[0197] As shown in Figure 1 , in the embodiment, the casing contamination evaluation system comprises a casing simulation device 100, a temperature control device 200, a pressure control device 300 and a liquid circulation subsystem 400.

[0198] The casing simulation device 100 comprises a shell 110, and the casing 120 is built-in the shell 110. The shell 110 is used to support the casing 120, and the casing 120 is arranged in the vertical direction. In the illustration of the embodiment, the vertical direction is indicated by the letter “Z” and the arrow (see Figure 5 or Figure 6 ).

[0199] The temperature control device 200 is arranged on the shell 110 of the casing simulation device 100. The temperature control device 200 can control the temperature in the casing simulation device 100 by heating, and thus the actual temperature in the well during drilling can be simulated.

[0200] The pressure control device 300 is connected with the casing simulation device 100, and the pressure control device 300 can control the pressure in the casing simulation device 100 by pressurization, thereby simulating the actual downhole pressure during drilling.

[0201] The liquid circulation subsystem 400 is connected with the casing simulation device 100, and the liquid circulation subsystem 400 is used to provide circulating drilling fluid and circulating cleaning fluid to the casing 120.

[0202] The liquid circulation subsystem 400 is provided with a particle size analyzer 450 for monitoring the particle size distribution of the circulating drilling fluid and the circulating cleaning fluid.

[0203] Since the casing 120 is arranged in the vertical direction, the circulating drilling fluid and the circulating cleaning fluid flow in the vertical direction in the casing 120. In this embodiment, the directions in which the circulating drilling fluid and the circulating cleaning fluid flow in the casing 120 are opposite.

[0204] It can be understood that the liquid circulation subsystem 400 can realize switching delivery of the drilling fluid and the cleaning fluid. When the evaluation of the pollution degree is performed, the liquid circulation subsystem 400 provides the circulating drilling fluid to the casing 120, and the inner wall of the casing 120 is polluted by the drilling fluid. Specifically, the drilling fluid remains on the inner wall of the casing 120 after flowing through the casing 120, thereby forming pollution to the inner wall of the casing 120. When the evaluation of the cleaning effect is performed, the liquid circulation subsystem 400 provides the circulating cleaning fluid to the casing 120, and the remaining drilling fluid on the inner wall of the casing 120 can be removed by the cleaning fluid, so as to achieve the purpose of cleaning the casing 120.

[0205] It can also be understood that, during the circulation of the drilling fluid, after the casing 120 is polluted, part of the components in the drilling fluid remains on the inner wall of the casing 120, and the particle size distribution of the drilling fluid during the circulation changes compared with the particle size distribution of the original drilling fluid. The pollution degree in the casing 120 can be judged by the change of the particle size distribution of the drilling fluid before and after the pollution. Similarly, the particle size distribution of the cleaning fluid before and after the cleaning of the casing 120 by the circulating cleaning fluid also changes, and thus the cleaning effect can be judged by the change of the particle size distribution of the cleaning fluid before and after the cleaning of the casing 120.

[0206] Therefore, the casing pollution and cleaning evaluation system provided in this embodiment integrates the evaluation of the pollution degree and the evaluation of the cleaning effect, and the temperature and pressure of the casing simulation device 100 are controlled by the temperature control device 200 and the pressure control device 300, thereby simulating the real downhole working condition.

[0207] Further, the embodiment also provides a casing pollution evaluation method, which is applied to the casing pollution evaluation system provided above. The casing pollution evaluation method comprises the following steps:

[0208] S100: input circulating drilling fluid into the casing 120, and control the temperature and pressure in the casing simulation device 100.

[0209] Specifically, the circulating drilling fluid is input into the casing 120 by the liquid circulation subsystem 400, heated by the temperature control device 200 to make the temperature in the casing simulation device 100 reach the actual temperature condition of the well, and pressurized by the pressure control device 300 to make the pressure in the casing simulation device 100 reach the actual pressure condition of the well. Thus, the authenticity of the simulation is ensured, so that the subsequent pollution degree evaluation is more valuable.

[0210] S200: after the first preset time length of drilling fluid circulation, the median particle size before and after the drilling fluid circulation (corresponding to the pollution of the casing 120 before and after) is obtained, and the pollution degree is evaluated according to the change of the median particle size before and after the drilling fluid circulation.

[0211] Specifically, the first preset time length is set according to the needs of the simulation, and in this embodiment, the first preset time length is not specifically limited, and the user can select according to actual needs.

[0212] Specifically, the particle size analyzer 450 is used to test the particle size distribution graph before and after the drilling fluid circulation, and the median particle size before and after the drilling fluid circulation is determined according to the particle size distribution graph before and after the drilling fluid circulation.

[0213] Specifically, the median particle size D 50 a before the drilling fluid circulation is used as a reference value, and the median particle size D 50 b after the drilling fluid circulation is used as a reference value, and the pollution degree is evaluated according to the ratio η1 of the difference D 50 a between the median particle size D 50 b after the drilling fluid circulation and the median particle size D 50 a before the drilling fluid circulation. 50 a) is greater, the pollution degree is more serious, and the η1 value is smaller, the pollution degree is lighter.

[0214] Wherein, a and b are only used to distinguish the median particle size.

[0215] S300: input circulating cleaning fluid into the casing 120, and control the temperature and pressure in the casing simulation device 100.

[0216] Specifically, the circulating cleaning fluid is input into the casing 120 by the liquid circulation subsystem 400, and can also be heated by the temperature control device 200 and pressurized by the pressure control device 300 to make the temperature and pressure in the casing simulation device 100 reach the actual temperature and pressure conditions of the well, so as to ensure the authenticity of the simulation, and further obtain more valuable data.

[0217] S400: After the second preset time of cleaning fluid circulation, obtain the median particle size before and after cleaning fluid circulation (corresponding to before and after cleaning of sleeve 120), and evaluate the cleaning effect based on the change in the median particle size before and after cleaning fluid circulation.

[0218] Specifically, the second preset duration is set according to the needs of the simulation. In this embodiment, the second preset duration is not specifically limited.

[0219] Specifically, the particle size distribution before and after the cleaning fluid circulation was tested using a particle size analyzer 450, and the median particle size before and after the cleaning fluid circulation was determined based on the particle size distribution before and after the cleaning fluid circulation.

[0220] Specifically, using the median particle size D after the cleaning fluid circulation 50 d and the median particle size D before cleaning fluid circulation 50 The difference between c and the median particle size D before the cleaning fluid circulation. 50 The ratio of c to η2 (η2=(D) 50 dD 50 c)÷D 50 c) Evaluate the cleaning effect; the larger the η2 value, the better the cleaning effect, and the smaller the η2 value, the worse the cleaning effect.

[0221] Among them, c and d are only used to distinguish the median particle size.

[0222] Median particle size is the median particle size, expressed in D. 50 This refers to the particle size at which the cumulative particle size distribution percentage of a sample reaches 50%. Physically, it means that 50% of the particles are larger than this size, and 50% are smaller. (D) 50 Also called median diameter or median particle size. D 50 It is often used to represent the average particle size of powder.

[0223] In one embodiment, the particle size distribution of the cleaning fluid before circulation is as follows: Figure 9 As shown, the particle size distribution after the cleaning fluid circulation is as follows: Figure 10 As shown. Furthermore, since the casing 120 is vertically oriented, it has an upper end and a lower end along the vertical direction. In this embodiment, the drilling fluid flows from the lower end to the upper end of the casing 120. The cleaning fluid flows in the opposite direction to the drilling fluid, i.e., from the upper end to the lower end of the casing 120.

[0224] in, Figure 9 and Figure 10 The horizontal axis represents particle size in micrometers, the vertical axis represents differential distribution, and Size in the figure represents peak size.

[0225] It can be understood that, in some embodiments, the casing contamination and cleaning evaluation system can also only perform steps S100 and S200 to only evaluate the contamination degree of the casing 120. Further, different drilling fluids can be replaced to evaluate the contamination degree of the casing 120 by different drilling fluids.

[0226] In other embodiments, the casing contamination and cleaning evaluation system can also only perform steps S300 and S400 to only evaluate the cleaning effect of the casing 120. Further, different cleaning fluids can be replaced to evaluate the cleaning effect of the contaminated casing 120 by different cleaning fluids.

[0227] The casing contamination and cleaning evaluation system provided by the embodiment can simulate the real working conditions of the casing 120, thereby greatly reducing the error of the simulation result, and thus more real and accurate data information can be obtained as a reference. When applied to actual operations, it can provide a reference for the selection of drilling fluids and cleaning fluids, and at the same time, efficient cleaning can be achieved.

[0228] It can be understood that, since the casing 120 is contaminated, drilling fluid remains on the inner wall of the casing 120, and thus the weight of the casing 120 will change compared to the weight when it is not contaminated. Therefore, the contamination degree in the casing 120 can also be determined by the weight change of the casing 120 before and after contamination. Similarly, the weight of the casing 120 will also change before and after cleaning, and thus the cleaning effect can be determined by the weight change of the casing 120 before and after cleaning. Based on this, in some embodiments, step S200 can further obtain the weight of the casing 120 before and after contamination, and evaluate the contamination degree according to the weight change of the casing 120 before and after contamination. Specifically, after the drilling fluid circulation is completed, the casing 120 can be taken out to weigh, to obtain the weight of the contaminated casing 120, and then compared with the weight of the casing 120 before contamination. Thus, by comparing and analyzing the weight change of the casing 120 with the preset test data, the contamination degree of the casing 120 can be evaluated. Based on this, in some embodiments, step S400 can further obtain the weight of the casing 120 before and after cleaning, and evaluate the cleaning effect according to the weight change of the casing 120 before and after cleaning. Specifically, the casing 120 can be taken out to weigh, to obtain the weight of the cleaned casing 120, and then compared with the weight of the casing 120 before cleaning. Thus, by comparing and analyzing the weight change of the casing 120 with the preset test data, the cleaning effect of the casing 120 can be evaluated.

[0229] Embodiment Two

[0230] Please refer to Figure 1 , Figure 3 , Figure 4 , Figure 8The embodiment provides a casing pollution evaluation system, and the embodiment is an improvement on the basis of the technical solution in the above-mentioned embodiment one. Compared with the above-mentioned embodiment one, the difference lies in that:

[0231] In the embodiment, the casing 100 is provided with a detection window 121, the detection window 121 is made of sapphire and is grid-divided (as shown in Figure 8 The detection window 121 can be used to detect the light transmittance before and after the casing 100 is polluted and / or before and after the casing 100 is cleaned, count the number of pollution grids, and thus evaluate the pollution degree and / or the cleaning degree based on the number of pollution grids.

[0232] The casing pollution evaluation method and system can be a casing pollution and cleaning evaluation method and system.

[0233] In the casing pollution evaluation system provided in the embodiment, the liquid circulation subsystem 400 can be provided with a particle size analyzer 450 (see Figure 4 ) for monitoring the particle size distribution of the circulating drilling fluid and the circulating cleaning fluid. Figure 3 ) can not be provided.

[0234] It can be understood that, during the circulation of the drilling fluid, the casing 120 is polluted, and the inner wall of the casing 120 is left with the drilling fluid. The light transmittance of the detection window 121 after the casing 120 is polluted changes compared with the light transmittance of the detection window 121 before the casing 120 is polluted. The pollution degree in the casing 120 can be determined by the change in the light transmittance of the detection window 121 before and after the pollution. Similarly, the casing 120 is cleaned by the circulating cleaning fluid, and the light transmittance of the detection window 121 before and after the cleaning also changes. Thus, the cleaning effect can be determined by the change in the light transmittance of the detection window 121 before and after the cleaning of the casing 120.

[0235] Further, the embodiment also provides a casing pollution evaluation method, which is applied to the casing pollution evaluation system provided in the embodiment. The casing pollution evaluation method provided in the embodiment is an improvement on the basis of the technical solution in the above-mentioned embodiment one. Compared with the above-mentioned embodiment one, the difference lies in that:

[0236] In step S200, after the drilling fluid circulates for the first preset time length, the number of pollution grids of the detection window 121 after the casing 120 is polluted is obtained, and the pollution degree is evaluated according to the number of pollution grids of the detection window 121 after the casing 120 is polluted.

[0237] Specifically, the pollution degree is evaluated by using the ratio of the number of polluted grids of the detection window 121 after the contamination of the sleeve 120 to the total number of grids of the detection window 121 of the sleeve 120; the greater the ratio of the number of polluted grids of the detection window 121 after the contamination of the sleeve 120 to the total number of grids of the detection window 121, the more serious the pollution degree; the smaller the ratio of the number of polluted grids of the detection window 121 after the contamination of the sleeve 120 to the total number of grids of the detection window 121, the less serious the pollution degree; in a specific embodiment, the number of grids of the detection window 121 is 15x15, i.e. 225, and the number of polluted grids of the detection window 121 after the contamination of the sleeve 120 is 180, at which time the pollution degree is 180÷225=80%;

[0238] In step S400, after the cleaning liquid is circulated for the second preset time length, the number of polluted grids of the detection window 121 after the cleaning of the sleeve 120 is obtained, and the cleaning effect is evaluated according to the change in the number of polluted grids of the detection window 121 before and after the cleaning of the sleeve 120.

[0239] Specifically, the cleaning effect is evaluated by using the ratio of the difference between the number of polluted grids of the detection window 121 before the cleaning of the sleeve 120 and the number of polluted grids of the detection window 121 after the cleaning of the sleeve 120 to the number of polluted grids of the detection window 121 before the cleaning of the sleeve 120; the greater the ratio of the difference between the number of polluted grids of the detection window 121 before the cleaning of the sleeve 120 and the number of polluted grids of the detection window 121 after the cleaning of the sleeve 120 to the number of polluted grids of the detection window 121 before the cleaning of the sleeve 120, the better the cleaning effect; the smaller the ratio of the difference between the number of polluted grids of the detection window 121 before the cleaning of the sleeve 120 and the number of polluted grids of the detection window 121 after the cleaning of the sleeve 120 to the number of polluted grids of the detection window 121 before the cleaning of the sleeve 120, the worse the cleaning effect.

[0240] In the sleeve pollution evaluation method provided in the embodiment, in S200, the particle size distribution graph before and after the circulation of the drilling fluid (corresponding to before and after the contamination of the sleeve 120) is obtained after the drilling fluid is optionally circulated for a first preset time length, and the pollution degree is evaluated according to the change in the particle size distribution before and after the circulation of the drilling fluid.

[0241] In the sleeve pollution and cleaning evaluation method provided in the embodiment, in S400, the particle size distribution graph before and after the circulation of the cleaning liquid (corresponding to before and after the cleaning of the sleeve 120) is obtained after the cleaning liquid is optionally circulated for a second preset time length, and the cleaning effect is evaluated according to the change in the particle size distribution before and after the circulation of the cleaning liquid.

[0242] Embodiment Three

[0243] Please refer to Figures 1 to 7The embodiment provides a casing pollution evaluation system, and the embodiment is improved on the basis of the technical solutions in the above-mentioned embodiment one and embodiment two, and the difference from the above-mentioned embodiment one and embodiment two is that:

[0244] In the embodiment, the casing simulation device 100 further comprises a weighing sensor 130 connected with the casing 120 and used for detecting the weight of the casing 120. By arranging the weighing sensor 130, the weight of the casing 120 in the casing 110 can be detected in real time, so that the casing 120 does not need to be disassembled and weighed, and the operation is more convenient.

[0245] In some embodiments, as shown in Figure 5 , the casing 120 is arranged in the vertical direction, and the weighing sensor 130 is supported below the casing 120. Therefore, the weighing sensor 130 is pressed by the casing 120.

[0246] In other embodiments, as shown in Figure 6 , the casing 120 is hung below the weighing sensor 130, and the weighing sensor 130 is pulled by the casing 120.

[0247] Please refer to Figures 1 to 4 , further, in the embodiment, the liquid circulating subsystem 400 comprises a circulating pump 410 and two liquid storage tanks 420. In order to more clearly describe the technical solutions of the present application, the two liquid storage tanks 420 are defined as a first liquid storage tank 421 and a second liquid storage tank 422.

[0248] The first liquid storage tank 421 is used for storing drilling fluid, and the second liquid storage tank 422 is used for storing cleaning fluid. The circulating pump 410 is connected with the casing 120 and the two liquid storage tanks 420 through pipelines 430, and a switch valve 440 is further arranged on the connecting pipeline 430 between the circulating pump 410 and the corresponding liquid storage tank 420. Therefore, by switching the on-off state of the switch valve 440, the drilling fluid and the cleaning fluid can be delivered into the casing 120.

[0249] Please refer to Figure 1 , Figure 2 , Figure 4 , further, in the embodiment, the liquid circulating subsystem 400 comprises a circulating pump 410; wherein the circulating pump 410 is connected with the casing 120 through pipelines 430; wherein the pipeline 430 between the circulating pump 410 and the casing 120 is connected with a particle size analyzer 450, and a switch valve 440 is further arranged on the connecting pipeline between the particle size analyzer 450 and the pipeline 430. Therefore, by switching the on-off state of the switch valve 440, the drilling fluid and the cleaning fluid in circulation can be sampled and the particle size distribution can be detected by using the particle size analyzer 450.

[0250] In some embodiments, the liquid circulating subsystem 400 comprises two circulating pumps 410 and two liquid storage tanks 420. In order to more clearly describe the technical solutions of the present application, the two circulating pumps 410 are defined as a first circulating pump (not shown) and a second circulating pump (not shown), and the two liquid storage tanks 420 are defined as a first liquid storage tank 421 and a second liquid storage tank 422.

[0251] The first liquid storage tank 421 is used for storing drilling fluid, and the second liquid storage tank 422 is used for storing cleaning fluid. The first circulating pump and the second circulating pump are both connected to the casing 120 through a pipeline 430. The first circulating pump 410 is further connected to the first liquid storage tank 421 through the pipeline 430, and the second circulating pump 410 is further connected to the second liquid storage tank 422 through the pipeline 430.

[0252] Further, the temperature control device 200 comprises a heating jacket 210 and a temperature controller 220. The heating jacket 210 is sleeved on the outer circumferential surface of the casing 110 of the casing simulation device 100. The temperature controller 220 is electrically connected (electrically connected) to the heating jacket 210. The temperature controller 220 is used for controlling the heating temperature of the heating jacket 210. When the heating temperature reaches a preset value, the temperature controller 220 controls the heating jacket 210 to stop heating.

[0253] Optionally, the heating temperature of the heating jacket 210 ranges from 25°C to 300°C, so as to simulate the actual temperature condition in the well. It should be understood that the above is only an example and does not limit the protection scope of the present application.

[0254] The pressure control device 300 comprises a gas storage tank 310 and a pressure gauge 320. The gas storage tank 310 is connected to the casing 120 of the casing simulation device 100 through a gas guide pipe 330. The gas storage tank 310 stores compressed gas with a preset pressure. The pressure gauge 320 is arranged on the gas guide pipe 330. In this way, the gas storage tank 310 can provide gas pressure to the casing 120, and the pressure gauge 320 can detect the size of the gas pressure in the casing 120. When the gas pressure detected by the pressure gauge 320 reaches a preset value, the gas supply of the gas storage tank 310 is stopped.

[0255] Further, the gas guide pipe 330 is further provided with a gas pressure valve 340, which is located between the pressure gauge 320 and the casing simulation device 100. The gas pressure valve 340 is used for controlling the on-off of the gas guide pipe 330.

[0256] Optionally, the gas stored in the gas storage tank 310 can be nitrogen, oxygen, carbon dioxide, or compressed air. It should be understood that the above is only an example and does not limit the protection scope of the present application.

[0257] Further, in some embodiments, a sealing member is arranged between the detection window 121 and the casing 120 to prevent liquid leakage.

[0258] Further, in some embodiments, a transparent window (not shown) can be provided on the heating jacket 210 and the housing 110, so that the contamination and cleaning conditions inside the tube can be observed without disassembling the sleeve 120.

[0259] Further, in some embodiments, the sleeve 120 can be disassembled.

[0260] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating the contamination of a bushing, characterized by, The method comprises the following steps: Step 1, obtaining a first characteristic before drilling fluid circulation; Step 2, performing drilling fluid circulation on the casing for a first preset time length; Step 3, obtaining a second characteristic after drilling fluid circulation; Step 4, evaluating the contamination degree in the casing according to the first characteristic and the second characteristic; After the step 4, the method comprises the following steps: Step 5, obtaining a third characteristic before cleaning fluid circulation; Step 6, performing cleaning fluid circulation on the casing for a second preset time length; Step 7, obtaining a fourth characteristic after cleaning fluid circulation; Step 8, evaluating the cleaning effect in the casing according to the third characteristic and the fourth characteristic; Before the step 1, the method comprises the following steps: obtaining a preset temperature value and a preset pressure value; controlling the temperature and pressure inside the casing according to the preset temperature value and the preset pressure value; The first characteristic is a first particle size distribution diagram, and the second characteristic is a second particle size distribution diagram; The step 4 comprises the following steps: Step 411, determining a first particle size median value before drilling fluid circulation according to the first particle size distribution diagram, and determining a second particle size median value after drilling fluid circulation according to the second particle size distribution diagram; Step 412, calculating a contamination value in the casing according to the first particle size median value before drilling fluid circulation and the second particle size median value after drilling fluid circulation; Step 413, evaluating the contamination degree in the casing according to the contamination value in the casing; The third characteristic is a third particle size distribution diagram, and the fourth characteristic is a fourth particle size distribution diagram; The step 8 comprises the following steps: Step 811, determining a third particle size median value before cleaning fluid circulation according to the third particle size distribution diagram, and determining a fourth particle size median value after cleaning fluid circulation according to the fourth particle size distribution diagram; Step 812, calculating a cleaning effect value in the casing according to the third particle size median value before cleaning fluid circulation and the fourth particle size median value after cleaning fluid circulation; Step 813, evaluating the cleaning effect in the casing according to the cleaning effect value in the casing; The contamination value in the casing is calculated by the following formula: η1= (D 50 a-D 50 b)÷D 50 a wherein η1is the contamination value inside the casing, D 50 a is the first median particle size before circulation of the drilling fluid, D 50 b is the second median particle size after circulation of the drilling fluid; The cleaning effect value in the casing is calculated by the following formula: η2= (D 50 d-D 50 c) ÷ D 50 c wherein η2 is a cleaning effect value in the sleeve, D 50 c is a third median particle size before circulation of the cleaning liquid, D 50 d is a fourth median particle size after circulation of the cleaning liquid; Or the first characteristic is a first pollution grid number before drilling fluid circulation, and the second characteristic is a second pollution grid number after drilling fluid circulation, The step 4 comprises the following steps: Step 431, obtaining a total number of grids of a detection window of the casing; Step 432, calculating a contamination degree ratio of a difference between the second pollution grid number and the first pollution grid number to the total number of grids according to the first pollution grid number and the second pollution grid number; Step 433, evaluating the contamination degree in the casing according to the contamination degree ratio; The third characteristic is a third pollution grid number before cleaning fluid circulation, and the fourth characteristic is a fourth pollution grid number after cleaning fluid circulation; The step 8 comprises the following steps: Step 831, calculating a cleaning effect ratio of a difference between the third pollution grid number and the fourth pollution grid number to the third pollution grid number according to the third pollution grid number and the fourth pollution grid number; Step 832, evaluating the cleaning effect in the casing according to the cleaning effect ratio.

2. A system for evaluating the contamination of a casing for use in the method of evaluating the contamination of a casing according to claim 1, characterized by The casing simulation device comprises a casing simulation device provided with a casing, a liquid circulating subsystem, a processor and a detection device, the detection device and the liquid circulating subsystem are connected with the casing simulation device, the processor is connected with the detection device, The detection device is used for acquiring a first feature before drilling fluid circulation; The liquid circulating subsystem is used for carrying out drilling fluid circulation on the casing for a first preset time length; The detection device is further used for acquiring a second feature after drilling fluid circulation; The processor is used for evaluating the pollution degree in the casing according to the first feature and the second feature; The detection device is further used for acquiring a third feature before cleaning fluid circulation; The liquid circulating subsystem is further used for carrying out cleaning fluid circulation on the casing for a second preset time length; The detection device is further used for acquiring a fourth feature after cleaning fluid circulation; The processor is further used for evaluating the cleaning effect in the casing according to the third feature and the fourth feature; The detection device is a particle size analyzer, and the particle size analyzer is connected with pipelines between the liquid circulating subsystem and the casing simulation device, The particle size analyzer is used for acquiring a first particle size distribution graph, a second particle size distribution graph, a third particle size distribution graph and a fourth particle size distribution graph; The processor is further used for determining a first particle size median value before drilling fluid circulation according to the first particle size distribution graph, and determining a second particle size median value after drilling fluid circulation according to the second particle size distribution graph; The processor is further used for calculating a pollution value in the casing according to the first particle size median value before drilling fluid circulation and the second particle size median value after drilling fluid circulation; The processor is further used for evaluating the pollution degree in the casing according to the pollution value in the casing; The processor is further used for determining a third particle size median value before cleaning fluid circulation according to the third particle size distribution graph, and determining a fourth particle size median value after cleaning fluid circulation according to the fourth particle size distribution graph; The processor is further used for calculating a cleaning effect value in the casing according to the third particle size median value before cleaning fluid circulation and the fourth particle size median value after cleaning fluid circulation; The processor is further used for evaluating the cleaning effect in the casing according to the cleaning effect value in the casing; The detection device is further used for acquiring a total number of grids of a detection window of the casing; The processor is further used for calculating a pollution degree ratio of a difference between the second pollution grid number and the first pollution grid number to the total number of grids according to the first pollution grid number and the second pollution grid number; The processor is further used for evaluating the pollution degree in the casing according to the pollution degree ratio; The processor is further used for calculating a cleaning effect ratio of a difference between the third pollution grid number and the fourth pollution grid number to the third pollution grid number according to the third pollution grid number and the fourth pollution grid number; The processor is further used for evaluating the cleaning effect in the casing according to the cleaning effect ratio.

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