Device and method for evaluating the displacement efficiency of cementing drilling fluid and the cleaning efficiency of flushing fluid

Abstract

The application provides a device and method for evaluating drilling fluid displacement efficiency and flushing efficiency of cementing, which comprises an annular fluid monitoring system, a circulation route, a simulated wellbore, an eccentricity adjusting tool and a deviation angle adjusting device. The annular fluid monitoring system comprises two high-power cameras and a computer system connected with the cameras. The circulation route comprises a circulating pump, a flow meter, a pressure gauge, a liquid storage tank and a hose. The simulated wellbore comprises a transparent cylindrical outer tube, two simulated wellbore covers at the ends and an eccentricity adjusting tool and an eccentricity adjuster support in the outer tube. The eccentricity adjusting tool comprises an eccentricity distance positioner and an eccentricity angle positioner. The deviation angle adjusting device comprises a deviation angle adjusting device base, a deviation angle adjusting disc and a simulated wellbore clamping seat. The application can provide reliable experimental data for designing the density difference of drilling fluid, preflush, spacer fluid and cement slurry, and can also evaluate the cleaning efficiency of flushing fluid, thus having a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling and completion technology, specifically to an apparatus and method for evaluating the displacement efficiency of cementing drilling fluid and the cleaning efficiency of flushing fluid. Background Technology

[0002] Currently, unconventional oil and gas resource exploration and development both domestically and internationally primarily utilizes long horizontal well technology. However, cementing operations in long horizontal wells present challenges such as difficulty in ensuring casing centering, low displacement efficiency of oil-based mud, and difficulty in cleaning oil-based mud cake, posing serious challenges to cementing quality. Therefore, accurately evaluating the displacement efficiency of drilling fluid and the cleaning efficiency of cleaning fluid under simulated casing eccentricity conditions is one of the key measures to improve the cementing quality of extended reach wells, horizontal wells, and ultra-long horizontal wells.

[0003] A patent search of existing "equipment for evaluating drilling fluid displacement efficiency and flushing fluid cleaning efficiency" revealed that the invention patent "A cementing flushing efficiency evaluation device and method" (CN 104863533B) is designed based on the principle of equal Reynolds number and can be used to evaluate the flushing efficiency of the flushing fluid on the first and second interfaces, but it cannot evaluate the flushing efficiency when the casing is eccentric; the utility model patent "Casing eccentricity adjustment mechanism" (CN 208918478 U) is applicable to the casing eccentricity adjustment mechanism of the cement slurry weight loss and gas channeling test device, which can realize continuous adjustment of casing eccentricity and solve the sealing problem of the device under casing eccentricity conditions, but it is not applicable to evaluating the flushing fluid cleaning efficiency; the utility model patent "A cementing flushing fluid test device" (CN 204627603 U) establishes a simulated wellbore and designs a support structure that can place the core or casing, but the support simply centers the core or casing and cannot adjust its eccentricity. The invention described above plays a good role in evaluating the mud cake removal efficiency under casing centering conditions. However, it cannot effectively simulate the cleaning efficiency of flushing fluid and observe the displacement efficiency of cement slurry under conditions of highly deviated or horizontal wells. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a device and method for evaluating the displacement efficiency of cementing drilling fluid and the cleaning efficiency of flushing fluid.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: constructing a device for evaluating the displacement efficiency of cementing drilling fluid and the cleaning efficiency of flushing fluid, including: annular fluid monitoring system, circulation route, simulated wellbore, eccentricity adjustment tool, and well inclination angle adjustment device;

[0006] The annular fluid monitoring system includes two high-magnification cameras located directly above and below the center of the simulated wellbore, and a computer connected to the two cameras.

[0007] The circulation route includes a circulation pump, a flow meter, a pressure gauge, a hose, a connecting joint, a gate valve, a No. 1 storage tank, and a No. 2 storage tank. The circulation pump is used to provide pressure to the simulated wellbore, so that the fluid flow in the pipeline is in a laminar, plug, or turbulent state. The pressure gauge is used to measure the pressure of the fluid entering the simulated wellbore, and the flow meter is used to measure the flow rate of the fluid entering the simulated wellbore. Both the No. 1 and No. 2 storage tanks have temperature control systems for heating the stored wellbore working fluid.

[0008] The simulated well casing includes a transparent cylindrical outer cylinder and simulated well casing covers at both ends. The eccentricity adjustment tool is set on an eccentricity adjuster bracket set inside the transparent cylindrical outer cylinder.

[0009] The eccentricity adjustment tool includes an eccentricity locator and an eccentricity angle locator. The eccentricity locator includes an upper nut, a lower nut, and a hollow short screw that slide freely on the eccentricity angle locator. The eccentricity angle locator is an eccentricity locator scale with graduations, a width slit in the middle, and spheres at both ends.

[0010] The well inclination angle adjuster includes a well inclination angle adjustment device base, a well inclination angle adjustment disc, and a simulated wellbore holder. The well inclination angle adjuster is an angle disc that adjusts the well inclination angle from 0 to 90°. The simulated wellbore holder fixes the simulated wellbore and has a fine threaded screw with a nut at the top and a hinge at the right angle of the bottom to the well inclination angle adjuster. The well inclination angle adjustment device base is the base that fixes the well inclination angle adjuster.

[0011] According to the above technical solution, the outer diameter of the two spheres at both ends of the eccentric angle locator is equal to the inner diameter of the hollow eccentric angle disk; the width of the crack allows for the free movement of the short screw; the thickness of the scale of the eccentric angle locator is less than the width of the circular crack in the inner ring of the eccentric angle disk; the eccentric angle disk is adjustable from 0 to 360°, and the thin-walled ring with a hollow center has a circular slit of a certain width along the innermost ring, the outer diameter of which is equal to the inner diameter of the simulated well shaft.

[0012] According to the above technical solution, the eccentricity adjuster support includes a cylinder for fixing the core or casing, two eccentricity adjusting tools, and four connecting columns for connecting the eccentricity adjusting tools. The cylinder for fixing the core or casing is connected by a screw inserted into a hollow short screw on the eccentricity positioner. The eccentricity adjusting tools are distributed at both ends of the eccentricity adjuster support and are connected by four connecting columns at equal intervals.

[0013] According to the above technical solution, the circulation route includes a circulation pump, a flow meter, a pressure gauge, a hose, a connecting joint, a gate valve, a No. 1 storage tank, and a No. 2 storage tank. The circulation pump can provide a certain pressure to the simulated wellbore, making the fluid flow in the pipeline laminar, plug, or turbulent state. The pressure gauge is used to measure the pressure of the fluid entering the simulated wellbore, and the flow meter is used to measure the flow rate of the fluid entering the simulated wellbore. Both the No. 1 and No. 2 storage tanks have temperature control systems that can heat the wellbore working fluids such as drilling fluid, pre-fluid, and cement slurry stored in the tank.

[0014] According to the above technical solution, the types of working fluids in the wellbore include drilling fluid, pre-flush fluid, and cement slurry.

[0015] The technical solution adopted by this invention to solve its technical problem is:

[0016] A method for evaluating the displacement efficiency of cementing drilling fluids, using the cementing drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device as described in the aforementioned technical solution, includes the following steps:

[0017] S1, Connect the entire loop route;

[0018] S2. Adjust the eccentricity angle dial and use the eccentricity adjustment tool to set the bushing eccentricity.

[0019] S3. Adjust the angle dial of the well inclination angle adjuster to set the well inclination angle;

[0020] S4. Fill the No. 1 storage tank with the drilling fluid to be tested and the No. 2 storage tank with the flushing fluid.

[0021] S5. Start the liquid storage tank heating program and set it to the experimental temperature;

[0022] S6. Open the gate valves in sequence and start the circulation pump to circulate for 30 minutes;

[0023] S7. Start the computer and turn on the two high-magnification cameras located directly above and below the center of the simulated well shaft;

[0024] S8. While closing all gate valves in the circulating drilling fluid channel, open the gate valve in the displacement fluid channel to replace the drilling fluid with flushing fluid.

[0025] S9. Based on the camera results obtained from the computer, calculate the time t required for the drilling fluid in the simulated wellbore to be completely replaced, record the data, and judge the effectiveness of different flushing fluids in replacing the same drilling fluid based on the length of time.

[0026] S10. Clean the entire experimental setup and end the experiment.

[0027] The technical solution adopted by this invention to solve its technical problem is:

[0028] A method for evaluating the cleaning efficiency of cementing flushing fluid, using the cementing drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device as described in the aforementioned technical solution, employing casing to simulate cementing casing and core samples to simulate formation, includes the following steps:

[0029] S1, Connect the entire loop route;

[0030] S2, Weigh the initial weight m0 of the casing or core;

[0031] S3. Adjust the eccentricity angle dial and use the eccentricity adjustment tool to set the bushing eccentricity.

[0032] S4. Adjust the angle dial of the well inclination angle adjuster to set the well inclination angle;

[0033] S5. Fill the No. 1 storage tank with the drilling fluid to be tested and the No. 2 storage tank with the flushing fluid.

[0034] S6. Start the liquid storage tank heating program and set it to the experimental temperature;

[0035] S7. Open the gate valves in sequence and start the circulation pump for 30 minutes.

[0036] S8. While closing all gate valves of the circulating drilling fluid channel, open the gate valve of the cleaning fluid circulation channel, replace the drilling fluid with flushing fluid, and clean the outer surface of the casing or core.

[0037] S9. Clean the outer surface of the casing or core according to the designed flushing fluid volume. After the flushing process is completed, take out the casing or core sample, dry it, and weigh it as m2.

[0038] S10, According to the formula Calculate the cleaning efficiency of the rinsing fluid;

[0039] S11. Clean the entire experimental setup and end the experiment.

[0040] Unlike existing technologies, the drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device and method for cementing in this invention can conveniently simulate the drilling fluid displacement efficiency and cementing flushing fluid cleaning efficiency under casing centering difference conditions in directional or horizontal wells. Furthermore, based on the readings of the flow meter and pressure gauge, the fluid flow pattern in the simulated wellbore can be easily controlled. It is easy to operate, multifunctional, and precisely adjustable, providing reliable experimental data for designing density differences between drilling fluid, cementing pre-flush fluid, isolation fluid, and cement slurry, and also evaluating the cleaning efficiency of the flushing fluid, showing promising application prospects. This device is characterized by simple operation, strong functionality, and wide applicability. Based on the flushing fluid cleaning efficiency evaluation, the flushing fluid system can be optimized; based on the measurement of flushing time, the flushing fluid dosage can be designed; and based on the displacement efficiency results, the density difference between the working fluids of the preceding and following processes in the wellbore can be designed. Attached Figure Description

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0042] Figure 1 This is a schematic diagram of the structure of a device for evaluating the displacement efficiency of cementing drilling fluid and the cleaning efficiency of flushing fluid provided by the present invention.

[0043] Figure 2 This is a schematic diagram of the structure of the drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device provided by the present invention when evaluating the flushing fluid cleaning efficiency.

[0044] Figure 3 This is a schematic diagram of the simulated wellbore structure in a drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device for cementing provided by the present invention.

[0045] Figure 4 This is a schematic diagram of the eccentricity adjustment tool in a cementing drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device provided by the present invention.

[0046] Figure 5 This is a schematic diagram of the eccentricity regulator bracket in a drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device for cementing provided by the present invention.

[0047] Figure 6 This is a schematic diagram illustrating an example of eccentricity adjustment in a drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device for cementing provided by the present invention.

[0048] Figure 7 This is a schematic diagram of a well inclination angle adjuster in a drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device provided by the present invention.

[0049] In the diagram: 1-Simulated well casing, 101-Simulated well casing cover, 102-Eccentricity adjuster bracket, 1021-Eccentricity adjustment tool, 10211-Eccentricity locator, 10212-Eccentricity locator scale, 10213-Eccentricity angle locator, 10214-Eccentricity adjuster bracket holder, 10215-Eccentricity angle adjustment disc, 10216-Eccentricity locator scale, 10217-Hollow short screw, 10218-Upper nut, 10219-Lower nut, 1022- Eccentricity locator; 1023-Fixed core or casing cylinder; 1024-Connecting column; 103-Core or casing; 2-Well inclination angle adjuster; 201-Well inclination angle adjuster base; 202-Well inclination angle adjuster angle adjustment disc; 203-Simulated wellbore holder; 3-Storage tank; 301-Storage tank No. 1; 302-Storage tank No. 2; 4-Circulation pump; 5-Displacement gauge; 6-Pressure gauge; 7-Connecting hose; 8-Right angle connector; 9-T-connector; 10-Gate valve; 11-Camera; 12-Computer. Detailed Implementation

[0050] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0051] See Figure 1 and Figure 2 The present invention provides an apparatus for evaluating the displacement efficiency of cementing drilling fluid and the cleaning efficiency of flushing fluid, including an annular fluid monitoring system, a circulation route, a simulated wellbore, an eccentricity adjustment tool, and a well inclination angle adjuster.

[0052] like Figure 1 As shown, the annular fluid monitoring system includes two high-magnification cameras 11 located directly above and below the center of the simulated wellbore 1, and a computer 12 connected to the two cameras 11;

[0053] like Figure 2 As shown, the circulation route includes a circulation pump 4, a flow meter 5, a pressure gauge 6, a hose 7, connecting joints 8 and 9, a gate valve 10, a storage tank 1 301, and a storage tank 2 302. The circulation pump 4 can provide a certain pressure to the simulated wellbore 1, making the fluid flow in the pipeline laminar, plug, or turbulent state. The pressure gauge 6 is used to measure the pressure of the fluid entering the simulated wellbore 1, and the flow meter 5 is used to measure the flow rate of the fluid entering the simulated wellbore 1. Both the storage tank 1 301 and the storage tank 2 302 have a temperature control system that can heat the wellbore working fluids such as drilling fluid, pre-fluid, and cement slurry stored in the tank.

[0054] like Figure 3As shown, the simulated well casing 1 includes a transparent cylindrical outer casing, simulated well casing covers at both ends, and an eccentricity adjustment tool 1021 and its eccentricity adjuster bracket 102 located inside the outer casing.

[0055] like Figure 4 As shown, the eccentricity adjustment tool 1021 includes an eccentricity locator 10211 and an eccentricity angle locator 10213. The eccentricity locator 10211 consists of an upper nut 10218, a lower nut 10219, and a hollow short screw 10217 that can slide freely on the eccentricity angle locator 10213. The eccentricity angle locator is an eccentricity locator scale 10212 with graduations, a certain width crack in the middle, and spheres at both ends of a certain thickness. The outer diameter of the spheres is equal to the inner diameter of the hollow eccentricity angle disk 10215. The width of the crack is sufficient to allow the free movement of the short screw 10217. The thickness of the thin cuboid is less than the width of the circular crack in the inner ring of the eccentricity angle disk 10215. The eccentricity angle disk 10215 can be adjusted from 0-360°, has a hollow thin-walled ring in the center, a circular slit of a certain width along the innermost ring, and its outer diameter is equal to the inner diameter of the simulated well shaft.

[0056] like Figure 5 As shown, the eccentricity adjuster bracket 102 includes a cylinder 1023 for fixing the core or casing, two eccentricity adjusting tools 1021, and four connecting columns 1024 connecting the eccentricity adjusting tools 1021. The cylinder 1023 for fixing the core or casing is connected by a screw inserted into a hollow short screw 10217 on the eccentricity locator 10211. The eccentricity adjusting tools 1021 are distributed at both ends of the eccentricity adjuster bracket 102 and are connected by the four connecting columns 1024 at equal intervals.

[0057] like Figure 6 The diagram shows the eccentricity of four types of cores or casings adjusted by the eccentricity adjustment tool 1021.

[0058] like Figure 7 As shown, the well inclination angle adjuster 2 includes a well inclination angle adjustment device base 201, a well inclination angle adjustment disc 202, and a simulated wellbore holder 203. The well inclination angle adjuster 2 is an angle disc 202 that can adjust the well inclination angle from 0 to 90°. The simulated wellbore holder 203 is a fine threaded rod with a nut at the top, which can fix the simulated wellbore 1 and has a hinge at the right angle between its bottom end and the well inclination angle adjuster. The well inclination angle adjustment device base 201 is a base for fixing the well inclination angle adjuster 2.

[0059] Furthermore, this invention provides a method for evaluating the displacement efficiency of cementing drilling fluid, using the cementing drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device as described in the foregoing technical solution, including the following steps:

[0060] S1, Connect the entire loop route;

[0061] S2. Adjust the eccentricity angle dial and use the eccentricity adjustment tool to set the bushing eccentricity.

[0062] S3. Adjust the angle dial of the well inclination angle adjuster to set the well inclination angle;

[0063] S4. Fill the No. 1 storage tank with the drilling fluid to be tested and the No. 2 storage tank with the flushing fluid.

[0064] S5. Start the liquid storage tank heating program and set it to the experimental temperature;

[0065] S6. Open the gate valves in sequence and start the circulation pump to circulate for 30 minutes;

[0066] S7. Start the computer and turn on the two high-magnification cameras located directly above and below the center of the simulated well shaft;

[0067] S8. While closing all gate valves in the circulating drilling fluid channel, open the gate valve in the displacement fluid channel to replace the drilling fluid with flushing fluid.

[0068] S9. Based on the camera results obtained from the computer, calculate the time t required for the drilling fluid in the simulated wellbore to be completely replaced, record the data, and judge the effectiveness of different flushing fluids in replacing the same drilling fluid based on the length of time.

[0069] S10. Clean the entire experimental setup and end the experiment.

[0070] This invention provides a method for evaluating the cleaning efficiency of cementing flushing fluid. The method uses the cementing drilling fluid displacement efficiency and flushing fluid cleaning efficiency evaluation device described in the foregoing technical solution to evaluate the efficiency. It utilizes casing to simulate cementing casing and core samples to simulate formation. The method includes the following steps:

[0071] S1, Connect the entire loop route;

[0072] S2, Weigh the initial weight m0 of the casing or core;

[0073] S3. Adjust the eccentricity angle dial and use the eccentricity adjustment tool to set the bushing eccentricity.

[0074] S4. Adjust the angle dial of the well inclination angle adjuster to set the well inclination angle;

[0075] S5. Fill the drilling fluid to be tested into storage tank 1 and storage tank 2 respectively, and fill the flushing fluid into storage tank 2.

[0076] S6. Start the liquid storage tank heating program and set it to the experimental temperature;

[0077] S7. Open the gate valves in sequence and start the circulation pump for 30 minutes.

[0078] S8. While closing all gate valves of the circulating drilling fluid channel, open the gate valve of the cleaning fluid circulation channel, replace the drilling fluid with flushing fluid, and clean the outer surface of the casing or core.

[0079] S9. Clean the outer surface of the casing or core according to the designed flushing fluid volume. After the flushing process is completed, take out the casing or core sample, dry it, and weigh it as m2.

[0080] S10, According to the formula Calculate the cleaning efficiency of the rinsing fluid;

[0081] S11. Clean the entire experimental setup and end the experiment.

[0082] This invention can conveniently simulate the drilling fluid displacement efficiency and cementing flushing fluid cleaning efficiency under casing centering difference conditions in directional or horizontal wells. Furthermore, based on the readings of the flow meter and pressure gauge, the fluid flow state of the simulated wellbore can be easily controlled. It is easy to operate, has multiple functions, and precise control. It can provide reliable experimental data for the design of density differences of drilling fluid, cementing pre-flush fluid, isolation fluid, and cement slurry, and can also evaluate the cleaning efficiency of flushing fluid, showing good application prospects.

[0083] The above are merely preferred embodiments of the present invention. Those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above. Any obvious improvements, substitutions or modifications made by those skilled in the art based on the present invention shall fall within the protection scope of the present invention.

Claims

1. A device for evaluating displacement efficiency and cleanup efficiency of a drilling fluid for cementing, characterized by, The application relates to a wellbore annulus fluid monitoring system, a circulating route, a simulated wellbore, an eccentricity adjusting tool and a well inclination adjusting device. The annulus fluid monitoring system comprises two high-power cameras located right above and below the center of the simulated wellbore and a computer connected with the two cameras. The circulating route comprises a circulating pump, a flow meter, a pressure gauge, a hose, a connecting joint, a gate valve, a No.1 liquid storage tank and a No.2 liquid storage tank. The simulated wellbore comprises a transparent cylindrical outer tube and two simulated wellbore covers at the ends. The eccentricity adjusting tool comprises an eccentricity distance positioner and an eccentricity angle positioner. The eccentricity distance positioner comprises an upper nut, a lower nut and a hollow short screw which are freely movable on the eccentricity angle positioner. The eccentricity angle positioner is a scale with a width crack in the middle and two spherical ends. The well inclination adjusting device comprises a well inclination adjusting device base, a well inclination adjusting disc and a simulated wellbore clamping seat.

2. The apparatus for evaluating displacement efficiency and cleanup efficiency of a drilling fluid for cementing according to claim 1, characterized in that: The eccentricity angle positioner has the same outer diameter as the hollow inner diameter of the eccentricity angle disc, the crack width satisfies the free movement of the short screw, and the thickness of the eccentricity distance positioner scale is smaller than the width of the circular crack in the inner circle of the eccentricity angle disc.

3. The apparatus for evaluating displacement efficiency and cleanup efficiency of a drilling fluid for cementing according to claim 1, characterized in that: The eccentricity angle disc adjusts 0-360 DEG and has a center hollow thin-wall ring with a certain width circular crack. The eccentricity adjusting tool is distributed at the two ends of the eccentricity adjusting device support and is connected by four connecting columns. The circulating route comprises a circulating pump, a flow meter, a pressure gauge, a hose, a connecting joint, a gate valve, a No.1 liquid storage tank and a No.2 liquid storage tank. The circulating pump can provide certain pressure for the simulated wellbore and make the fluid flow state in the pipeline be laminar flow, plug flow or turbulent flow. The pressure gauge is used for measuring the pressure of the fluid entering the simulated wellbore. The flow meter is used for measuring the flow size of the fluid entering the simulated wellbore. The No.1 liquid storage tank and the No.2 liquid storage tank have temperature control systems and can heat the stored drilling fluid, preflush and cement slurry wellbore working fluid.

4. The apparatus for evaluating the displacement efficiency of a drilling fluid and the cleaning efficiency of a spacer fluid for use in cementing a well as set forth in claim 2, wherein: The wellbore working fluid types include drilling fluid, preflush, cement slurry.

5. A method for evaluating the displacement efficiency of a cementing drilling fluid, using the apparatus for evaluating the displacement efficiency of a cementing drilling fluid and the cleaning efficiency of a flushing fluid according to any one of claims 1 to 4, characterized by: The method comprises the following steps: S1, connecting the whole circulation route; S2, adjusting the eccentric angle dial, and setting the casing eccentricity by using the eccentricity adjusting tool; S3, adjusting the angle dial of the hole inclination angle adjuster, and setting the hole inclination angle; S4, respectively loading the drilling fluid to be tested into the No. 1 liquid storage tank, and loading the flushing fluid into the No. 2 liquid storage tank; S5, starting the liquid storage tank temperature rising program, and setting the experimental temperature; S6, opening the gate valves in sequence, and starting the circulation pump to circulate for 30 min; S7, starting the computer, and opening the two high-magnification cameras located right above and right below the center of the simulated wellbore; S8, while closing the gate valves of the circulating drilling fluid channel, opening the gate valves of the displacement fluid channel, and displacing the drilling fluid with the flushing fluid; S9, according to the camera results obtained on the computer, calculating the time t for the drilling fluid in the simulated wellbore to be displaced clean, recording the data, and judging the displacement effect of different flushing fluids on the same drilling fluid according to the time length; S10, cleaning the whole experimental device, and ending the experiment.

6. A method for evaluating the cleaning efficiency of a flushing fluid for cementing, using the evaluation device for evaluating the displacement efficiency of a drilling fluid and the cleaning efficiency of a flushing fluid for cementing according to any one of claims 1 to 4, characterized by, The casing is used to simulate the cementing casing, and the core is used to simulate the formation, and the method comprises the following steps: S1, connecting the whole circulation route; S2, weighing the initial weight m0 of the casing or the core; S3, adjusting the eccentric angle dial, and setting the casing eccentricity by using the eccentricity adjusting tool; S4, adjusting the angle dial of the hole inclination angle adjuster, and setting the hole inclination angle; S5, respectively loading the drilling fluid to be tested into the No. 1 liquid storage tank, and loading the flushing fluid into the No. 2 liquid storage tank; S6, starting the liquid storage tank temperature rising program, and setting the experimental temperature; S7, opening the gate valves in sequence, and starting the circulation pump to circulate for 30 min; S8, while closing the gate valves of the circulating drilling fluid channel, opening the gate valves of the cleaning fluid circulation channel, displacing the drilling fluid with the cleaning fluid, and flushing the outer surface of the casing or the core; S9, according to the designed flushing fluid amount for cleaning the outer surface of the casing or the core, after the flushing process is completed, taking out the casing or the core sample to dry, and weighing the mass as m2; S10, according to the formula Calculate the cleaning efficiency of the rinse liquid; S11, cleaning the whole experimental device, and ending the experiment.

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