Anti-wax and anti-scaling detection device and method for oil pipe coating / coating layer

Abstract

The invention relates to the field of oil pipe anti-wax and anti-scaling detection, in particular to an oil pipe coating / coating anti-wax and anti-scaling detection device and method. A crude oil exploitation simulation system is arranged to provide a crude oil exploitation simulation environment for a to-be-tested coating / coating oil pipe sample; a crude oil circulation system for testing is arranged to provide crude oil for the crude oil exploitation simulation system and simulate the flow velocity and flow of the crude oil; by arranging the heating system, high-temperature environment simulation of the crude oil exploitation simulation system is achieved; by arranging the refrigerating system, the extremely cold environment of the coated / coated oil pipe sample to be tested is simulated; the corrosive mixed gas generation system is arranged to realize corrosion environment simulation, the control system is arranged to realize automatic control of the device, the device is simple, the oil extraction environment can be greatly restored, parameters are diversified and controllable, the detection efficiency is high, the result accuracy is good, and a scientific and reliable test basis is provided for oil field material selection. The problems of low efficiency and unreliable detection result of paraffin and scaling prevention detection of the oil pipe coating / coating layer are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wax and scale prevention detection for oil pipes, and specifically to a wax and scale prevention detection device and method for coatings on oil pipes. Background Art

[0002] Crude oil, especially high-wax and high-water-content crude oil, is a complex multi-component mixture. Currently, more than 90% of the produced crude oil is high-wax crude oil. During the exploitation and transportation of crude oil, due to the influence of environmental conditions such as in-pipe temperature, pressure, flow rate, and corrosive media, wax and inorganic salts in the crude oil are easily deposited and adsorbed on the inner wall of the oil pipe, resulting in wax and scale formation in the oil pipe, reducing the flow area of the oil pipe. As the wax or scale layer becomes thicker, the oil pressure continuously drops, and even the well may be blocked, seriously affecting the oil production of the oilfield.

[0003] Currently, materials with low surface energy, low roughness, or heat insulation properties are selected and coated on the inner wall of the oil pipe. By reducing the polarity and roughness of the inner wall of the oil pipe or increasing the in-pipe temperature, the purpose of wax and scale prevention for the oil pipe is achieved. In the prior art, the wax and scale prevention performance of the coating on the oil pipe is detected through a high-temperature and high-pressure autoclave coating performance detection and a static immersion test device. This method cannot accurately simulate the crude oil exploitation environment, the reliability of the detection result is low, and there are many human factors in the experimental process. The experimental results are not universal, resulting in large deviations in the detection results, unable to accurately test the wax and scale prevention effect of the coating on the oil pipe, and with high labor intensity and low detection efficiency.

[0004] Therefore, there is an urgent need for a high-efficiency and convenient wax and scale prevention detection device for small samples of coatings on oil pipes to improve the accuracy and detection efficiency of the wax and scale prevention detection results of coatings on oil pipes. Summary of the Invention

[0005] Aiming at the problems in the prior art that in the process of detecting the wax and scale prevention of coatings on oil pipes by humans, due to the inability to accurately simulate the crude oil exploitation environment and the large influence of human factors, the detection results are inaccurate, the detection efficiency is low, and a scientific test basis cannot be provided for oilfield material selection, the present invention provides a wax and scale prevention detection device and method for coatings on oil pipes.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A wax and scale prevention detection device for coatings on oil pipes includes a control system, a heating system, a refrigeration system, a corrosive mixed gas generation system, a test crude oil circulation system, and a crude oil exploitation simulation system;

[0008] The crude oil exploitation simulation system internally contains a test coated / covered oil pipe sample, and is used to provide a crude oil exploitation environment for the test coated / covered oil pipe sample;

[0009] The test crude oil circulation system is connected to the crude oil exploitation simulation system, and is used to provide crude oil for the crude oil exploitation simulation system, and simulate the environment where the crude oil flows through the test coated / covered tubing specimen.

[0010] The heating system is connected to the test crude oil circulation system and the crude oil exploitation simulation system, and is used to heat the test crude oil circulation system and provide a high-temperature environment for the crude oil exploitation simulation system.

[0011] The refrigeration system is connected to the crude oil exploitation simulation system, and is used to provide a low-temperature environment for the crude oil exploitation simulation system.

[0012] The corrosive mixed gas generation system is connected to the test crude oil circulation system, and is used to provide a corrosion environment for the crude oil exploitation simulation system together with the test crude oil circulation system.

[0013] The heating system, the corrosive mixed gas generation system and the test crude oil circulation system are all connected to the control system.

[0014] Further, the crude oil exploitation simulation system includes a sample chamber, a bracket is arranged inside the sample chamber, and the test coated / covered tubing specimen is placed on the bracket; a first oil bath heating device is arranged outside the sample chamber, a first thermocouple is inserted in the first oil bath heating device, and the first thermocouple is connected to the control system.

[0015] Preferably, the bracket is a stepped bracket.

[0016] Preferably, a first temperature controller is arranged on the first thermocouple, and the first temperature controller is connected to the control system.

[0017] Further, the test crude oil circulation system includes an oil storage tank, the oil storage tank is filled with test crude oil, a forward circulation oil pipe and a reverse circulation oil pipe are inserted in the test crude oil; the forward circulation oil pipe is connected to the input end of the crude oil exploitation simulation system, and the nozzle of the forward circulation oil pipe is aligned with the test coated / covered tubing specimen; the reverse circulation oil pipe is connected to the output end of the crude oil exploitation simulation system and is used to return the test crude oil entering the crude oil exploitation simulation system to the oil storage tank; circulation pumps are arranged on the forward circulation oil pipe and the reverse circulation oil pipe and are used to provide input and output power for the test crude oil in the crude oil exploitation simulation system, and the circulation pumps are connected to the control system.

[0018] Preferably, an oil flow controller is arranged on the circulation pump, and the oil flow controller is connected to the control system.

[0019] Furthermore, the heating system includes an oil bath tank disposed outside the oil storage tank. The oil bath tank is internally provided with heating oil, and a second oil bath heating device is arranged outside the oil bath tank. A second thermocouple is inserted into the oil bath tank, and the second thermocouple is connected to the control system.

[0020] Preferably, a second temperature controller is arranged on the second thermocouple, and the second temperature controller is connected to the control system.

[0021] Preferably, the refrigeration system includes a circulating liquid nitrogen generator, and the circulating liquid nitrogen generator is connected to the crude oil production simulation system for refrigerating the crude oil production simulation system.

[0022] A method for detecting wax and scale prevention of a tubing coating / coating layer using the above detection device includes the following steps:

[0023] Obtain the daily crude oil production, tubing specifications, and wellhead temperature of oilfield oil production;

[0024] Calculate the crude oil flow rate according to the daily crude oil production and tubing specifications of oilfield oil production;

[0025] Calculate the well depth temperature where wax or asphalt precipitation is likely to occur at the oil production site according to the wellhead temperature;

[0026] Place the tubing specimen with the coating / coating layer to be tested inside the crude oil production simulation system;

[0027] Apply the test crude oil to the tubing specimen with the coating / coating layer to be tested according to the calculated crude oil flow rate and well depth temperature, so that the test crude oil continuously flows through the tubing specimen with the coating / coating layer to be tested;

[0028] Take out the tubing specimen with the coating / coating layer to be tested at fixed time intervals, weigh it, measure the thickness, observe the surface of the tubing specimen with the coating / coating layer to be tested, and classify and analyze the wax and scale prevention of the tubing specimen with the coating / coating layer to be tested.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] An anti-wax and anti-scale detection device for the coating of oil pipes. By setting up a crude oil production simulation system, it provides a crude oil production simulation environment for the oil pipe sample with the coating to be tested. By connecting a test crude oil circulation system to the crude oil production simulation system, it realizes providing crude oil for the crude oil production simulation system and simulates the environment of crude oil flowing through the oil pipe sample with the coating to be tested. By setting up a heating system for the crude oil production simulation system, the heating system is connected to the test crude oil circulation system and the crude oil production simulation system, realizing the simulation of a high-temperature environment in the crude oil production simulation system. The refrigeration system is connected to the crude oil production simulation system, realizing the simulation of a low-temperature environment in the crude oil production simulation system and the rapid cooling of the detection device. The test crude oil circulation system is also connected to a corrosive mixed gas generation system, realizing the simulation of a corrosive environment in the crude oil production simulation system. The setting of the control system realizes the electrical control of the entire detection device, with stronger automation. This detection device can realize the composite simulation of the temperature, flow rate, flow volume, and corrosive environment of crude oil production, and can automatically simulate and detect the waxing or scaling degree of different oil pipe samples with the coating to be tested under different environments and different periods. At the same time, it can realize the research on the influence of different conditions on the performance of the oil pipe sample with the coating to be tested, providing a scientific basis for the improvement of the oil pipe with the coating to be tested. It has a high degree of automation, little influence of human factors in the test, high precision, and high efficiency, and can provide a reliable basis for the subsequent research on the applicability evaluation of the oil pipe coating. Compared with the current high-temperature and high-pressure autoclave coating performance detection and static immersion test devices, it has the advantages of highly simulating the on-site working conditions, automatic parameter control, and more reliable detection results.

[0031] The crude oil production simulation system includes a sample chamber. Inside the sample chamber, there is a bracket, and the oil pipe sample with the coating to be tested is placed on the bracket. Outside the sample chamber, there is a first oil bath heating device, and a first thermocouple is inserted in the first oil bath heating device. The first thermocouple is connected to the control system. The setting of the sample chamber provides a simulation space for the oil pipe sample with the coating to be tested, the bracket provides support for the oil pipe sample with the coating to be tested, and the first thermocouple and the first oil bath heating device keep the sample chamber warm, ensuring the stability of the simulated temperature in the sample chamber and further improving the accuracy of the detection.

[0032] The stepped bracket can provide a certain slope for the oil pipe sample with the coating to be tested, enabling the test crude oil to flow evenly through the wall of the oil pipe sample with the coating to be tested and improving the accuracy of the detection results.

[0033] The first thermocouple is provided with a first temperature controller, and the first temperature controller is connected to the control system, facilitating the control of the temperature in the sample chamber and ensuring temperature stability.

[0034] The settings of the oil storage tank, the forward circulation oil pipe, the reverse circulation oil pipe and the circulation pump enable the test crude oil in the crude oil exploitation simulation system to circulate through the to-be-tested coated / covered oil pipe, improving the stability of the detection device. At the same time, the recycling of crude oil is realized, meeting the detection requirements of small laboratory specimens.

[0035] The setting of the crude oil flow controller enables the automatic control of the flow rate and velocity of the test crude oil, further improving the simulation accuracy.

[0036] The settings of the oil bath tank, the second oil bath heating device and the second thermocouple enable the control of the oil temperature of the test crude oil, making the oil temperature of the specimen flowing through the to-be-tested coated / covered oil pipe more stable, less affected by the external environment, and further ensuring the simulation accuracy.

[0037] The setting of the second temperature controller enables the automatic control of the temperature of the second thermocouple.

[0038] The refrigeration system includes a circulating liquid nitrogen generator, which is connected to the crude oil exploitation simulation system. While providing refrigeration for the crude oil exploitation simulation system, it can also cool down the entire detection device.

[0039] The present invention also provides a method for detecting wax and scale prevention of the coated / covered layer of an oil pipe using the above detection device. This method calculates the crude oil flow rate by obtaining the daily crude oil production, oil pipe specifications and wellhead temperature of oilfield oil production, calculates the well depth temperature where wax is likely to form or asphalt precipitate at the oil production site, and uses the above detection device to realize the detection of wax and scale prevention of the to-be-tested coated / covered oil pipe specimen. The method is simple, easy to operate, and has high detection efficiency and good reliability. Description of the Drawings

[0040] Figure 1 It is a schematic diagram of a device for detecting wax and scale prevention of the coated / covered layer of an oil pipe according to the present invention.

[0041] Figure 2 It is a flow chart for detecting wax and scale prevention of the coated / covered layer of an oil pipe according to the present invention.

[0042] Figure 3 It is a structure diagram of the coated / covered layer of an oil pipe in an embodiment of the present invention.

[0043] Figure 4 It is the coated / covered layer 1# specimen before the test in an embodiment of the present invention.

[0044] Figure 5 It is the coated / covered layer 2# specimen before the test in an embodiment of the present invention.

[0045] Figure 6 It is the specimen without the coated / covered layer before the test in an embodiment of the present invention.

[0046] Figure 7 This is the wax deposition situation of the coating layer 1# sample of the embodiment of the present invention after 16 hours.

[0047] Figure 8 This is the wax deposition situation of the coating layer 2# sample of the embodiment of the present invention after 16 hours.

[0048] Figure 9 This is the wax deposition situation of the sample without coating layer of the embodiment of the present invention after 16 hours.

[0049] Among them, 1 - second oil bath heating device, 2 - heating resistance wire, 3 - heating oil, 4 - oil storage tank, 5 -, 6 - forward circulation oil pipe, 7 - reverse circulation oil pipe, 8 - first thermocouple, 9 - bracket, 10 - oil pipe sample of the coating layer to be tested, 11 - crude oil for the test, 12 - control system, 13 - second temperature controller, 14 - crude oil flow controller, 15 - first temperature controller, 16 - corrosive mixed gas generation system, 17 - sample chamber, 18 - first oil bath heating device, 19 - circulation pump, 20 - second thermocouple, 21 - gas flow controller, 22 - base pipe of the oil pipe, 23 - coating layer of the oil pipe. Detailed implementation manners

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0052] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0053] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0054] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0055] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] The following further elaborates on the present invention with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0057] See Figure 1 , the present invention discloses a wax and scale prevention detection device for a tubing coating, including a control system 12, a heating system, a refrigeration system, a corrosive mixed gas generation system 16, a test crude oil circulation system, and a crude oil production simulation system;

[0058] The crude oil production simulation system is used to provide a crude oil production environment for the tubing specimen 10 with the coating to be tested, including a sample chamber 17. Inside the sample chamber 17, there is a bracket 9. The bracket 9 is a stepped bracket with a cavity inside. The tubing specimen 10 with the coating to be tested is placed on the bracket 9. The tubing specimen 10 with the coating to be tested is in the shape of a tile. Outside the sample chamber 17, there is a first oil bath heating device 18. A first thermocouple 8 is inserted into the first oil bath heating device 18. The first thermocouple 8 is provided with a first temperature controller 15. Both the first temperature controller 15 and the first thermocouple 8 are connected to the control system 12.

[0059] The test crude oil circulation system is used to provide crude oil for the crude oil exploitation simulation system, simulating the environment where the crude oil flows through the test coated / covered tubing specimen 10, including a storage oil tank 4. An oil bath 4 is arranged outside the storage oil tank 4. The oil bath 4 is a stainless-steel oil bath. Heating oil 3 is arranged inside the oil bath 4. A second oil bath heating device 1 is arranged outside the oil bath 4, and the second oil bath heating device 1 is provided with heating resistance wires 2. A second thermocouple 20 is inserted into the oil bath 4. A second temperature controller 13 is arranged on the second thermocouple 20, and the second temperature controller 13 is connected to the control system 12. The storage oil tank 4 is internally filled with test crude oil 11. A forward circulation oil pipe 6 and a reverse circulation oil pipe 7 are inserted into the test crude oil 11. Both the forward circulation oil pipe 6 and the reverse circulation oil pipe 7 are silica gel pipes. The forward circulation oil pipe 6 is connected to the input end of the sample chamber 17, and the nozzle of the forward circulation oil pipe 6 is aligned with the test coated / covered tubing specimen 10. The reverse circulation oil pipe 7 is connected to the output end of the sample chamber 17, and is used to return the test crude oil 11 that enters the sample chamber 17 to the storage oil tank 4. A circulation pump 19 is arranged on the forward circulation oil pipe 6 and the reverse circulation oil pipe 7, and is used to provide input and output power for the test crude oil 11 in the sample chamber 17. The circulation pump 19 is a stepping motor high-precision circulation pump. An oil flow controller 14 is arranged on the circulation pump 19, and the oil flow controller 14 is connected to the control system.

[0060] The heating system is used to provide a high-temperature environment for the crude oil exploitation simulation system, including an oil bath 4 arranged outside the storage oil tank 4. Heating oil 3 is arranged inside the oil bath 4. A second oil bath heating device 1 is arranged outside the oil bath 4. A second thermocouple 20 is inserted into the oil bath 4. A second temperature controller 13 is arranged on the second thermocouple 20, and the second temperature controller 13 is connected to the control system 12.

[0061] The refrigeration system is used to provide a low-temperature environment for the crude oil exploitation simulation system, including a circulating liquid nitrogen generator. The output end of the circulating liquid nitrogen generator is connected to the internal cavity of the bracket 9, and is used to cool the test coated / covered tubing specimen 10 to simulate the working condition of a lower wellhead temperature in alpine regions. Preferably, a mixture of circulating liquid nitrogen and alcohol can be introduced.

[0062] The corrosive mixed gas generating system 16 is used to provide a corrosive environment for the crude oil exploitation simulation system together with the test crude oil circulation system. The corrosive mixed gas output end of the corrosive mixed gas generating system 16 is connected to the forward circulation oil pipe 6. A gas flow controller 21 is arranged on the corrosive mixed gas generating system 16, and the gas flow controller 21 is connected to the control system 12.

[0063] In use, the control system 12 controls the flow rate, temperature, temperature in the sample chamber, and corrosive mixed gas of the experimental crude oil 11 according to the temperature required for the experiment. The circulation pump 19 is turned on to draw the experimental crude oil 11 in the storage tank 5 through the forward circulation oil pipe 6 to the surface of the test coating / cladding oil pipe specimen 10. After the experimental crude oil 11 flows through the surface of the test coating / cladding oil pipe specimen 10, it enters the sample chamber 17 and then returns to the storage tank 5 through the reverse circulation oil pipe 7, realizing the continuous circulation of the high-temperature experimental crude oil 11 acting on the surface of the test coating / cladding oil pipe specimen 10. At the same time, according to the corrosive gas environment at the oil production site, the corrosive mixed gas is introduced into the sample chamber 17, and the circulation period is set according to the test requirements, realizing the crude oil at different temperatures flowing through the test coating / cladding oil pipe specimens 10 at different flow rates. Observe the wax or scale formation degree of the coating / cladding on the inner wall of the test coating / cladding oil pipe specimen 10 at different times, and evaluate the wax prevention performance of the oil pipe coating / cladding by means of specimen weight gain, wax morphology and thickness measurement, etc. The flow rate range is 0 - 6000 ml / min; the highest temperature is 200 °C, and the lowest temperature is -40 °C.

[0064] See Figure 2 , the present invention also provides a method for detecting wax and scale prevention of an oil pipe coating / cladding using the above detection device, including the following steps:

[0065] S1: Obtain the daily crude oil production, oil pipe specifications, and wellhead temperature of oilfield production;

[0066] S2: Calculate the crude oil flow rate according to the daily crude oil production and oil pipe specifications of oilfield production;

[0067] S3: Calculate the well depth temperature where wax or asphalt precipitation is likely to occur at the oil production site according to the wellhead temperature;

[0068] S4: Place the test coating / cladding oil pipe specimen 10 inside the crude oil production simulation system;

[0069] S5: Apply the experimental crude oil 11 to the test coating / cladding oil pipe specimen 10 according to the calculated crude oil flow rate and well depth temperature, so that the experimental crude oil 11 continuously flows through the test coating / cladding oil pipe specimen 10;

[0070] S6: Take out the test coating / cladding oil pipe specimen 10 at fixed time intervals, weigh it, measure the thickness, observe the surface of the test coating / cladding oil pipe specimen 10, and classify and analyze the wax and scale prevention of the test coating / cladding oil pipe specimen 10.

[0071] This method calculates the crude oil flow rate by obtaining the daily crude oil production, tubing specifications, and wellhead temperature in oilfield oil production, calculates the well depth temperature where wax or asphalt precipitation is likely to occur at the oil production site, and uses the above detection device to achieve the detection of wax and scale prevention for the tubing specimens of the coating / lining to be tested. The method is simple, easy to operate, and has high detection efficiency and good reliability.

[0072] Example 1

[0073] Two tubing specimens with different anti-corrosion coatings / lining of Φ73.02mm×5.51mm were subjected to an internal coating / lining wax prevention performance test. The specimen structure is shown in Figure 3 , including the tubing base pipe 22 and the tubing coating / lining 23. The specific steps are as follows:

[0074] According to the daily crude oil production and tubing specifications in oilfield oil production, the crude oil flow rate was calculated to be 2000 ml / min, and according to the wellhead temperature, the well depth temperature where wax or asphalt precipitation is likely to occur at the site was calculated to be 80 °C.

[0075] Three groups of specimens were cut from the on-site tubing and were respectively denoted as Coating 1#, Coating 2#, and Uncoated Specimen 3#, and were longitudinally cut and processed into tile-shaped specimens of 100mm×30mm×9.17mm;

[0076] 40 L of on-site oilfield crude oil was respectively filled into the storage tank 5 and the sample chamber 17, and the specimens of Coating 1#, Coating 2#, and Uncoated Specimen 3# were respectively placed on the support 9;

[0077] The two oil bath heating devices were set to the same temperature of 80 °C, and the test crude oil 11 and the specimens were heated simultaneously;

[0078] When the temperature reached the set temperature, the flow rate of the high-temperature crude oil was set to 2000 ml / min, and the circulation pump 19 was started. The high-temperature crude oil flowed continuously through the specimens of Coating 1#, Coating 2#, and Uncoated Specimen 3# at a certain flow rate;

[0079] At the time points of 16 h, 72 h, and 168 h of the experimental cycle, the specimens were respectively taken out, weighed, thickness measured, and photographed, as shown in Figures 4 to 9 , and the wax and scale prevention grading and applicability evaluation were carried out for different coating specimens.

[0080] Example 2

[0081] Two tubing specimens with different anti-corrosion coatings / lining of Φ88.9mm×9.17mm were subjected to an internal coating / lining wax prevention performance test. The specific steps are as follows:

[0082] According to the daily crude oil production of oil fields and the tubing specifications, the crude oil flow rate is calculated to be 1800 ml / min. According to the wellhead temperature, the well depth temperature where wax is likely to form or asphalt precipitate at the site is 40°C. At the same time, since the improvement is in a high-cold area in winter, the bottom surface temperature is -20°C.

[0083] Cut three groups of specimens from the on-site tubing and label them as inner coating 1#, inner coating 2#, and uncoated specimen 3# respectively. Longitudinally cut and process them into tile-shaped specimens of 100 mm × 30 mm × 9.17 mm.

[0084] Fill 40L of on-site crude oil from the oil field into storage tank 5 and sample chamber 17 respectively, and place inner coating 1#, inner coating 2#, and uncoated specimen 3# on support 9 respectively.

[0085] Set the temperature of the second oil bath heating device to 40°C and heat the test crude oil 11.

[0086] Pass a circulating liquid nitrogen and alcohol mixture into the cavity of support 9, and control the temperature of the inner coating 1#, inner coating 2#, and uncoated specimen 3# to be maintained at -20°C by controlling the temperature of the alcohol with liquid nitrogen passed in.

[0087] When the temperature reaches the set temperature, set the flow rate of the high-temperature crude oil to 1800 ml / min, turn on circulating pump 9, and the high-temperature crude oil continuously flows over the surfaces of inner coating 1#, inner coating 2#, and uncoated specimen 3# respectively.

[0088] At the time points of 16h, 72h, and 168h in the experimental cycle, take out the specimens respectively for thickness measurement, weighing, and photographing, and conduct wax and scale prevention grading and applicability evaluation on different coating specimens.

[0089] In summary, the present invention provides a device and method for detecting wax and scale prevention of oil pipe coatings. It can simulate different working conditions, set different test temperatures, and conduct constant-temperature flow tests. It can also set a temperature change program to conduct variable-temperature flow tests to detect the influence of different temperatures on the wax prevention performance of the oil pipe coatings. At the same time, when the wellhead temperature in alpine regions is relatively low, the device can simulate that the lowest temperature of the oil pipe can reach -40°C, and realize the detection of the wax prevention performance of the inner coating of the oil pipe when the crude oil temperature and the sample temperature are different. The device can simulate the flow rate of high-temperature crude oil under working conditions, conduct tests with a constant flow rate, or set a flow rate change program to detect the change law of the wax prevention performance of the oil pipe coatings at different flow rates. According to the requirements of oilfield users, the device can conduct detection tests at different time periods, set different high-temperature crude oil circulation cycles, and detect the influence of the time accumulation effect on the wax prevention performance of the oil pipe coatings. The device can simultaneously conduct wax prevention detection on multiple samples with different coatings under the same test conditions, and there is no secondary chemical pollution between the coatings and the crude oil, greatly saving the evaluation time. The test crude oil used in the device can be recycled or fresh crude oil can be continuously added for detection to meet the detection needs of laboratory small samples. The device highly integrates the control of parameters such as crude oil temperature, flow rate, oil pipe sample temperature, crude oil circulation cycle, and the addition of corrosive gases in an automated control module, improving the test accuracy and efficiency. It realizes the applicability evaluation of the oil pipe coatings based on the corresponding relationship between parameters such as the temperature difference between the crude oil and the surface of the oil pipe coating, the flow rate and flow of the crude oil, the content of corrosive gases, and time, and the degree of wax and scale formation on the surface of the oil pipe coating sample. It has the advantages of convenient operation, high detection efficiency, diverse and controllable parameters, and intuitive and reliable data, and can provide a scientific and reliable test basis for oilfield material selection.

[0090] The above are only the preferred embodiments of the present invention, and are not intended to limit the technical solutions of the present invention. Those skilled in the art should understand that without departing from the spirit and principles of the present invention, the technical solutions can be modified and replaced simply, and these modifications and replacements also fall within the protection scope covered by the claims.

Claims

1. An anti-wax and anti-scaling detection device for tubing coating Characterized in that it includes a control system (12), a heating system, a refrigeration system, a corrosive mixed gas generation system (16), a test crude oil circulation system, and a crude oil production simulation system; The crude oil production simulation system internally places a tubing specimen (10) with a coating to be tested, and is used to provide a crude oil production environment for the tubing specimen (10) with a coating to be tested; The test crude oil circulation system is connected to the crude oil production simulation system and is used to provide crude oil for the crude oil production simulation system to simulate the environment where crude oil flows through the tubing specimen (10) with a coating to be tested; The heating system is connected to the test crude oil circulation system and the crude oil production simulation system, and is used to heat the test crude oil circulation system and provide a high-temperature environment for the crude oil production simulation system; The refrigeration system is connected to the crude oil production simulation system and is used to provide a low-temperature environment for the crude oil production simulation system; The corrosive mixed gas generation system (16) is connected to the test crude oil circulation system and is used to provide a corrosion environment for the crude oil production simulation system together with the test crude oil circulation system; The heating system, the corrosive mixed gas generation system (16), and the test crude oil circulation system are all connected to the control system (12).

2. The anti-wax and anti-scaling detection device for tubing coating according to claim 1 Characterized in that The crude oil production simulation system includes a sample chamber (17), a bracket (9) is arranged inside the sample chamber (17), and the tubing specimen (10) with a coating to be tested is placed on the bracket (9); a first oil bath heating device (18) is arranged outside the sample chamber (17), a first thermocouple (8) is inserted in the first oil bath heating device (18), and the first thermocouple (8) is connected to the control system (12).

3. The anti-wax and anti-scaling detection device for tubing coating according to claim 2 Characterized in that The bracket (9) is a stepped bracket.

4. The anti-wax and anti-scaling detection device for tubing coating according to claim 2 Characterized in that A first temperature controller (15) is arranged on the first thermocouple (8), and the first temperature controller (15) is connected to the control system (12).

5. The anti-wax and anti-scaling detection device for tubing coating according to claim 1 Characterized in that The test crude oil circulation system includes a storage oil tank (4) which is filled with test crude oil (11) inside. A forward circulation oil pipe (6) and a reverse circulation oil pipe (7) are inserted into the test crude oil (11). The forward circulation oil pipe (6) is connected to the input end of the crude oil exploitation simulation system, and the nozzle of the forward circulation oil pipe (6) is aligned with the test tubing specimen (10) with coating. The reverse circulation oil pipe (7) is connected to the output end of the crude oil exploitation simulation system and is used to return the test crude oil (11) entering the crude oil exploitation simulation system to the storage oil tank (4). Circulation pumps (19) are arranged on the forward circulation oil pipe (6) and the reverse circulation oil pipe (7) to provide input and output power for the test crude oil (11) in the crude oil exploitation simulation system, and the circulation pumps (19) are connected to a control system (12).

6. The wax and scale prevention detection device for the tubing coating according to claim 5, characterized in that, an oil flow controller (14) is arranged on the circulation pump (19), and the oil flow controller (14) is connected to the control system.

7. The wax and scale prevention detection device for the tubing coating according to claim 5, characterized in that, the heating system includes an oil bath tank (4) arranged outside the storage oil tank (4). Heating oil (3) is arranged inside the oil bath tank (4), a second oil bath heating device (1) is arranged outside the oil bath tank (4), a second thermocouple (20) is inserted into the oil bath tank (4), and the second thermocouple (20) is connected to the control system (12).

8. The wax and scale prevention detection device for the tubing coating according to claim 7, characterized in that, a second temperature controller (13) is arranged on the second thermocouple (20), and the second temperature controller (13) is connected to the control system (12).

9. The wax and scale prevention detection device for the tubing coating according to claim 1, characterized in that, the refrigeration system includes a circulating liquid nitrogen generator which is connected to the crude oil exploitation simulation system and is used to refrigerate the crude oil exploitation simulation system.

10. A method for detecting wax and scale prevention of a tubing coating using the detection device according to any one of claims 1-9, characterized in that, it includes the following steps: Obtain the daily crude oil production, tubing specifications and wellhead temperature of oilfield oil production; Calculate the crude oil flow rate according to the daily crude oil production and tubing specifications of oilfield oil production; Calculate the well depth temperature where wax or asphalt precipitation is likely to occur at the oil production site according to the wellhead temperature; Place the test tubing specimen (10) with coating inside the crude oil exploitation simulation system; Apply the test crude oil (11) to the test tubing specimen (10) with coating according to the calculated crude oil flow rate and well depth temperature, so that the test crude oil (11) continuously flows through the test tubing specimen (10) with coating; Take out the test tubing specimen (10) with coating at fixed time intervals, weigh it, measure its thickness, observe the surface of the test tubing specimen (10) with coating, and classify and analyze the wax and scale prevention of the test tubing specimen (10) with coating.

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