A performance testing method for high-temperature sealing thread grease for oil casing.

Abstract

This invention belongs to the field of drilling technology for oil and gas wells or geothermal wells, specifically relating to a performance testing method for high-temperature sealing thread grease used in oil casing. The method includes at least the following steps: 1) Performing thread grease performance testing according to standards to verify whether the performance meets the standard requirements; measuring the friction coefficient of the thread grease to obtain friction coefficient parameters; 2) Conducting full-scale physical tests to test the performance of the thread grease: threading and unthreading tests, wherein before threading and unthreading, the threading torque is corrected using the thread grease friction coefficient obtained in step 1), and after unthreading, the thread grease is cleaned, the threads are inspected, and the lubricity of the thread grease is verified; 3) A high-temperature sealing verification test, wherein the sample obtained in step 2) is dried at a set temperature for a drying time of not less than 12 hours, and after drying, the high-temperature sealing verification test in step 3) is performed to verify the sealing performance of the thread grease. This method can meet the performance testing requirements for high-temperature sealing thread grease.

Description

Technical Field

[0001] This invention belongs to the field of drilling technology for oil and gas wells or geothermal wells, and specifically relates to a performance testing method for high-temperature sealing thread grease for oil casing. Background Technology

[0002] As the energy industry deepens its exploration of extreme and complex geological environments, oil and gas extraction is shifting from conventional to unconventional development. The connection technology of oil casing and tubing has become a key factor in ensuring the safety and efficiency of exploration and development, especially in deep and ultra-deep wells and high-temperature, high-pressure gas well drilling. The sealing safety and reliability of threaded connections directly affect the success of the operation. Thread grease, as a key material for improving the performance of threaded connections, not only lubricates and seals the threads, but its quality and performance must also meet requirements to prevent failure of the threaded connection structure and seal.

[0003] As drilling conditions in oil and gas fields become increasingly demanding, traditional API thread greases can no longer meet the requirements of these demanding conditions. Many companies have begun to produce thread greases with special performance characteristics. However, due to the inconsistent quality and performance of these products, traditional testing methods cannot verify their quality and performance, and there is a lack of effective quality and performance evaluation methods. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a performance testing method for high-temperature sealing thread grease used in oil casing, to meet the testing requirements for high-temperature sealing thread grease.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for testing the performance of high-temperature sealing thread grease for oil casing includes at least the following steps:

[0007] 1) According to the standard (e.g. GB / T 23512 standard), the density, dropping point, evaporation, oil separation, cone penetration, flash point, water leaching, water resistance, gas escape, corrosivity and corrosion resistance of the thread grease samples are tested to screen out the samples whose physical and chemical properties meet the standard requirements; the friction coefficient of the thread grease samples is measured, the friction coefficient is calculated, and the friction coefficient parameters of the thread grease are obtained.

[0008] Based on the above technical solution, the performance of thread grease can be effectively evaluated.

[0009] Furthermore, the performance testing method for high-temperature sealing thread grease for oil casing also includes the following steps:

[0010] 2) Conduct full-scale physical tests to test the performance of threadlocker grease:

[0011] Full-size physical threading and unthreading tests: First, the thread parameters and geometric dimensions of the threading and unthreading tubing are measured to eliminate the influence of thread machining on the threading and unthreading performance. Second, the thread surface is cleaned and the thread grease is applied evenly to verify that the amount of thread grease meets the standard or technical requirements. The tubing or casing is tested for threading and unthreading according to standard methods (e.g., GB / T 21267). Before threading and unthreading, the threading torque is revised using the thread grease friction coefficient obtained in step 1). After threading and unthreading, the thread grease is cleaned and the thread surface is checked to verify the lubricity of the thread grease, thereby determining whether the lubricity of the thread grease meets the usage requirements.

[0012] 3) High-temperature sealing performance verification test: The sample obtained in step 2) is dried at a set temperature for a drying time of not less than 12 hours; after drying, a sealing verification test is performed at a set temperature. The test pressurizing medium is dry nitrogen gas. The pressurization is performed according to the actual use requirements to verify the high-temperature sealing performance of the thread grease.

[0013] Based on the above technical solutions, it is possible to comprehensively evaluate whether the performance of thread grease meets the design and usage requirements.

[0014] Furthermore, step 1) also includes any one or more of the following tests, and the results are used as the basis for screening the performance of high-temperature sealing thread grease:

[0015] Microscopic morphology test: Measure the microscopic morphology of the sealing grease under different component contents and forms;

[0016] Viscoelastic behavior test: Measure the storage modulus and loss modulus of thread grease under different component contents and morphologies;

[0017] Viscosity-temperature characteristic test: Measure the change in viscosity of threadlocker grease as temperature increases;

[0018] Dynamic thermomechanical property testing: Measuring the relationship between the dynamic thermomechanical properties of thread grease and time, temperature, or frequency;

[0019] Differential scanning calorimetry test: Measure the relationship between heat absorption and release of thread grease and temperature to obtain the change in its stability with temperature;

[0020] Thermogravimetric analysis: measures the thermal decomposition information and thermal stability of thread grease.

[0021] Based on the above technical solution, the accuracy of optimal sample screening can be further improved.

[0022] In the above technical solution:

[0023] Examining the microstructure can clarify the composition and distribution of thread grease.

[0024] Examining viscoelastic behavior can help avoid substandard viscoelasticity in thread grease and quantify viscoelastic values.

[0025] Examining viscosity-temperature characteristics can clarify the sensitivity of thread grease viscosity to temperature changes.

[0026] Examining dynamic thermomechanical properties can quantify the dynamic mechanical properties of thread grease.

[0027] Examining the stability of thread grease as it changes with temperature can determine its maximum applicable temperature.

[0028] Examining the results of thermogravimetric analysis can clarify the sensitivity of thread grease quality to temperature changes.

[0029] Specifically: through step 1), the solid particle content and the ratio of base oil to base grease of the optimal sample are obtained.

[0030] Specifically: The micromorphology test is performed by using scanning electron microscopy to analyze the influence of the number and size of the mixed particles in the thread grease on their distribution morphology.

[0031] Specifically, the viscoelastic behavior test measures the storage modulus and loss modulus of thread grease to analyze its ability to recover its original shape after being deformed under stress.

[0032] Specifically, the thermogravimetric analysis calculates the thermal stability parameters of the thread grease material by measuring the mass change at different temperatures, including the peak temperature and peak height of the weight loss peak.

[0033] Preferably, the fastening and unfastening tests are performed at least three times.

[0034] Preferably, the high-temperature sealing thread grease is used in oil well pipe thread connection structures in drilling technology fields such as oil wells, gas wells, or geothermal wells.

[0035] The beneficial effects of this invention are:

[0036] The present invention provides a performance testing method for high-temperature sealing thread grease for oil casing. This method uses experimental methods to determine the microscopic, physicochemical properties, solid particle content, and morphological distribution of the thread grease, thereby determining the optimal grease content and component ratio. Furthermore, the friction coefficient of the thread grease is obtained through friction coefficient testing, and the threading and unthreading torques of the oil casing are corrected. The lubricity and high-temperature ultimate sealing performance of the thread grease are verified through threading and unthreading tests and high-temperature sealing tests. Attached Figure Description

[0037] Figure 1 This is an example of the microstructure of thread grease with different graphite powder particle sizes in Example 3.

[0038] Figure 2 This is an example of the microstructure of the sealing grease under different component ratios in Example 4.

[0039] Figure 3 This is an example of the storage modulus G' of thread sealant with different particle sizes and graphite powder doping amounts in Example 3.

[0040] Figure 4 This is an example of the storage modulus G' of the thread sealing grease under different component ratios in Example 4.

[0041] Figure 5 This is an example of the viscosity curves of thread sealing grease under different component ratios in Example 4.

[0042] Figure 6 This is an example of the dynamic thermomechanical property curves of thread grease with different component ratios in Example 4.

[0043] Figure 7 This is an example of the TG thermogravimetric curve of the thread grease in Example 4. Detailed Implementation

[0044] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0045] Unless otherwise specified, the test methods used in the embodiments are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0046] Example 1

[0047] The performance testing method for high-temperature sealing thread grease for oil casing includes the following steps:

[0048] 1) Measurement of basic performance parameters: According to the standard, the density, dropping point, evaporation, oil separation, cone penetration, flash point, water leaching, water resistance, gas escape, corrosivity and corrosion resistance of the thread grease samples are tested, and samples that meet the standard requirements are screened.

[0049] 2) Friction coefficient measurement: The friction coefficient of the thread grease sample was measured according to the standard, the friction coefficient was calculated, and the friction coefficient parameter of the thread grease was obtained as 0.8.

[0050] 3) Thread parameter and geometric dimension measurement: Determine the range of error in the measurement of oil casing thread parameters and geometric dimensions, measure the thread parameters and geometric dimensions of oil casing for top and bottom threading, remove samples with large thread parameter deviations, and eliminate the influence of thread processing on top and bottom threading performance;

[0051] 4) Threading and unthreading test: Apply the thread grease to the tubing or casing and perform three threading and unthreading tests according to the standard method. Before threading and unthreading, revise the threading and unthreading torque using the friction coefficient of the thread grease. If the actual threading torque is 20,000 N·m, then the revised threading torque is 16,000 N·m. Record the threading and unthreading torque for each threading and unthreading test. After each unthreading test, clean the thread grease and check the thread surface to verify the lubricity of the thread grease.

[0052] 5) High-temperature sealing test: The sample obtained in step 4) was dried at a set temperature of 180℃ for 12 hours. After drying, a sealing verification test was conducted at a set temperature of 180℃. The test pressurizing medium was dry nitrogen, and the loading pressure was 60MPa to verify the high-temperature sealing performance of the thread grease.

[0053] Example 2

[0054] The performance testing method for high-temperature sealing thread grease for oil casing includes the following steps:

[0055] 1) Measurement of basic performance parameters: According to the standard, the density, dropping point, evaporation, oil separation, cone penetration, flash point, water leaching, water resistance, gas escape, corrosivity and corrosion resistance of the thread grease samples are tested, and samples that meet the standard requirements are screened.

[0056] 2) Friction coefficient measurement: The friction coefficient of the thread grease sample was measured according to the standard, the friction coefficient was calculated, and the friction coefficient parameter of the thread grease was obtained as 1.2.

[0057] 3) Thread parameter and geometric dimension measurement: Determine the range of error in the measurement of oil casing thread parameters and geometric dimensions, measure the thread parameters and geometric dimensions of oil casing for top and bottom threading, remove samples with large thread parameter deviations, and eliminate the influence of thread processing on top and bottom threading performance;

[0058] 4) Coupling and uncoupling test: The thread grease to be verified is used to perform three coupling and uncoupling tests on the oil pipe or casing according to the standard method. Before coupling, the coupling torque is revised with the friction coefficient of the thread grease. The revised coupling torque is 24000 N·m. The coupling and uncoupling torques must be recorded for each coupling and uncoupling. After each uncoupling, the thread grease is cleaned and the thread surface is checked to verify the lubricity of the thread grease.

[0059] 5) High-temperature sealing test: The sample obtained in step 4) is dried at a set temperature of 180℃ for 12 hours. After drying, a sealing verification test is performed at a set temperature of 180℃. The test medium is dry nitrogen. The pressure is applied according to the actual use requirements, with a loading pressure of 60MPa, to verify the high-temperature sealing performance of the thread grease.

[0060] Example 3

[0061] The performance testing method for high-temperature sealing thread grease for oil casing includes the following steps:

[0062] 1) Microscopic morphology test: Samples with the same composition ratio but different filler contents, sizes, and morphologies were selected. A small amount of sample was placed on the stage using a scanning electron microscope (SEM). The equipment was evacuated, and the working voltage and current were set. Selective areas were selected, and the test samples were photographed. The data was saved. Analysis showed that in this embodiment, when the content of 15%–25% 100-mesh graphite powder or flakes was 15%–25%, the resulting thread grease was uniform. Figure 1 As shown;

[0063] 2) Viscoelastic behavior test: The storage modulus G' and loss modulus G" of the selected thread grease samples were measured. Analysis showed that the 15%–18% graphite-doped thread grease in this embodiment exhibited good viscoelasticity. Figure 3 As shown;

[0064] 3) Viscosity-temperature characteristic test: The viscosity-temperature characteristic test was carried out on the thread grease sample selected in 2). The analysis showed that the viscosity of the 400 mesh and 800 mesh graphite-doped thread grease in this embodiment fluctuated greatly with temperature, which showed that the viscosity was unstable with temperature.

[0065] 4) Dynamic thermomechanical test: The thread grease sample from 3) was selected for dynamic thermomechanical performance test. The analysis showed that when the graphite content was 15% in this embodiment, the dynamic storage modulus G', loss modulus G”, and loss tangent all showed an increasing trend. The thread grease did not undergo glass transition and its sealing performance was good.

[0066] Combining the analysis of steps 1) to 4) above, select thread grease samples with uniform microstructure, good viscoelasticity, and stable viscosity-temperature characteristics for step 5) to 8) measurement to test the sealing performance of high-temperature sealing thread grease.

[0067] 5) Measurement of basic performance parameters: density, dropping point, evaporation rate, oil separation rate, cone penetration, flash point, water leaching, water resistance, gas escape rate, corrosivity and corrosion resistance of the sample;

[0068] 6) Friction coefficient measurement: The friction coefficient of the thread grease sample is measured according to the standard, the friction coefficient is calculated, and the friction coefficient of the thread grease is obtained.

[0069] 7) Thread parameter and geometric dimension measurement: Determine the range of error for the variation of oil casing thread parameters and geometric dimensions, measure the thread parameters and geometric dimensions of oil casing for top and bottom threading, remove samples with large thread parameter deviations, and eliminate the influence of thread processing on top and bottom threading performance;

[0070] 8) Coupling and uncoupling test: The thread grease to be verified shall be applied to the oil pipe or casing and subjected to three coupling and uncoupling tests according to the standard method. Before coupling, the coupling torque shall be corrected by the friction coefficient of the thread grease. The corrected coupling torque shall be 24000 N·m. The coupling and uncoupling torque shall be recorded for each coupling and uncoupling test. After each uncoupling test, the thread grease shall be cleaned and the thread surface shall be checked to verify the lubricity of the thread grease.

[0071] 9) High-temperature sealing test: The sample obtained in step 8) is dried at a set temperature of 180℃ for 12 hours. After drying, a sealing verification test is performed at a set temperature of 180℃. The test medium is dry nitrogen gas. The pressure is applied according to the actual use requirements, with a loading pressure of 60MPa, to verify the high-temperature sealing performance of the thread grease.

[0072] Example 4

[0073] The performance testing method for high-temperature sealing thread grease for oil casing includes the following steps:

[0074] 1) Microscopic morphology test: Different proportions of components A and B were selected. A small sample was placed on the stage using a scanning electron microscope (SEM). The equipment was evacuated, and the operating voltage and current were set. Selective areas were selected, and the test samples were photographed. The data was saved, and analysis showed that in this embodiment, after the addition of A and B, no lumpy graphite appeared, and the thread grease was more uniform. Figure 2 As shown;

[0075] 2) Viscoelastic behavior test: Storage modulus G' and loss modulus G" were measured on the thread grease samples selected in 1). Analysis showed that in this embodiment, the thread grease with an A to B ratio of 2.5% to 2.5% had the highest storage modulus, indicating that the thread grease with this ratio has good elasticity. Figure 4 As shown;

[0076] 3) Viscosity-temperature characteristic test: The thread grease sample from step 2) was selected for viscosity-temperature characteristic testing. The viscosity-temperature characteristic curve was obtained. Analysis showed that in this embodiment, when the ratio of A to B was 3%–2%, the viscosity change with increasing temperature was minimal. Figure 5 As shown;

[0077] 4) Dynamic thermomechanical performance test: Dynamic thermomechanical performance tests were conducted on the thread grease samples selected in step 3). Analysis showed that in this embodiment, when the ratio of A to B was 3%–2%, the dynamic storage modulus G', loss modulus G”, and loss tangent of the thread grease exhibited a trend of first decreasing and then increasing with increasing test temperature. The thread grease demonstrated good sealing and lubrication properties at high temperatures. Figure 6 As shown;

[0078] 5) Differential Scanning Calorimetry (DSC) Test: The thread grease sample from step 4) was subjected to DSC test. Analysis showed that in this embodiment, there was essentially no heat absorption or release within the 25℃~100℃ range. A significant exothermic peak occurred within the 100℃~170℃ range. Slow heat absorption was observed within the 200℃~350℃ range. Within the 25℃~100℃ range, the thread grease exhibited a certain degree of performance stability.

[0079] 6) Thermogravimetric Analysis: Thermogravimetric analysis was performed on the thread grease sample from step 5). The analysis showed that in this embodiment, there was essentially no mass loss within the temperature range of 25℃ to 100℃. When the temperature was raised to approximately 180℃, the thread grease lost about 5% of its mass. When the temperature reached 325℃, the remaining mass decreased rapidly. Figure 7 As shown;

[0080] Based on the analysis of steps 1) to 6) above, select thread grease samples with uniform microstructure, good viscoelasticity, stable viscosity-temperature characteristics, and good dynamic thermomechanical properties for measurement in steps 7) to 10). Test the high-temperature sealing performance of the thread grease according to the applicable temperature determined by the tests in steps 5) to 6).

[0081] 7) Measurement of basic performance parameters: density, dropping point, evaporation rate, oil separation rate, cone penetration, flash point, water leaching, water resistance, gas escape rate, corrosivity and corrosion resistance of the sample;

[0082] 8) Friction coefficient measurement: The friction coefficient of the thread grease sample is measured according to the standard, the friction coefficient is calculated, and the friction coefficient of the thread grease is obtained.

[0083] 9) Thread parameter and geometric dimension measurement: Determine the range of error in the measurement of oil casing thread parameters and geometric dimensions, measure the thread parameters and geometric dimensions of oil casing for top and bottom threading, remove samples with large thread parameter deviations, and eliminate the influence of thread processing on top and bottom threading performance.

[0084] 10) Coupling and uncoupling test: The thread grease to be applied is used to perform three coupling and uncoupling tests on the oil pipe or casing according to the standard method. Before coupling, the coupling torque is corrected by the friction coefficient of the thread grease. The corrected coupling torque is 24000 N·m. The coupling and uncoupling torques must be recorded for each coupling and uncoupling. After each uncoupling, the thread grease is cleaned and the thread surface is checked to verify the lubricity of the thread grease.

[0085] 11) High-temperature sealing test: The sample obtained in step 10) is dried at a set temperature of 180℃ for 12 hours. After drying, a sealing verification test is performed at a set temperature of 180℃. The test medium is dry nitrogen gas. The pressure is applied according to the actual use requirements, with a loading pressure of 60MPa, to verify the high-temperature sealing performance of the thread grease.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing the performance of high-temperature sealing thread grease for oil casing, characterized in that, At least the following steps are included: According to the standard, the density, dropping point, evaporation rate, oil separation rate, cone penetration, flash point, water leaching, water resistance, gas escape rate, corrosivity and corrosion resistance of thread grease samples were tested to screen out samples whose physicochemical properties meet the standard requirements. The friction coefficient of the thread grease sample was measured according to the standard, the friction coefficient was calculated, and the friction coefficient parameter of the thread grease was obtained.

2. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 1, characterized in that, Includes the following steps: 1) According to the standard, the density, dropping point, evaporation, oil separation, cone penetration, flash point, water leaching, water resistance, gas escape, corrosivity and corrosion resistance of the thread grease samples were tested, and the samples whose physical and chemical properties meet the standard requirements were screened out. The friction coefficient of the thread grease sample was measured according to the standard, the friction coefficient was calculated, and the friction coefficient parameter of the thread grease was obtained. 2) Conduct full-scale physical tests to test the performance of threadlocker grease: Full-size physical threading and unthreading tests: First, the thread parameters and geometric dimensions of the oil sleeve used for threading and unthreading are measured to eliminate the influence of thread machining on the threading and unthreading performance. Second, the thread surface is cleaned and the thread grease is applied evenly to the thread surface to verify that the amount of thread grease meets the standard or technical requirements. The oil tube or sleeve is tested for threading and unthreading according to the standard method. Before threading and unthreading, the threading torque is revised using the thread grease friction coefficient obtained in step 1). After threading and unthreading, the thread grease is cleaned and the thread surface condition is checked to verify the lubricity of the thread grease, thereby determining whether the lubricity of the thread grease meets the usage requirements. 3) High-temperature sealing performance verification test: The sample obtained in step 2) is dried at a set temperature for a drying time of not less than 12 hours; after drying, a sealing verification test is performed at a set temperature. The test pressurizing medium is dry nitrogen gas. The pressurization is performed according to the actual use requirements to verify the high-temperature sealing performance of the thread grease.

3. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 1, characterized in that, Step 1) also includes any one or more of the following tests, and the results will be used as the basis for screening the performance of high-temperature sealing thread grease: Microscopic morphology test: Measure the microscopic morphology of the sealing grease under different component contents and forms; Viscoelastic behavior test: Measure the storage modulus and loss modulus of thread grease under different component contents and morphologies; Viscosity-temperature characteristic test: Measure the change in viscosity of threadlocker grease as temperature increases; Dynamic thermomechanical property testing: Measuring the relationship between the dynamic thermomechanical properties of thread grease and time, temperature, or frequency; Differential scanning calorimetry test: Measure the relationship between heat absorption and release of thread grease and temperature to obtain the change in its stability with temperature; Thermogravimetric analysis: measures the thermal decomposition information and thermal stability of thread grease.

4. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 3, characterized in that: Step 1) yields the data on the solid particle content and the ratio of base oil to base grease for the optimal sample.

5. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 3, characterized in that: The microstructure test was performed by using scanning electron microscopy to analyze the influence of the number and size of the mixed particles in the thread grease on their distribution morphology.

6. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 3, characterized in that: The viscoelastic behavior test measures the storage modulus and loss modulus of the thread grease and analyzes its ability to recover its original shape after being deformed under stress.

7. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 3, characterized in that: The thermogravimetric analysis is performed to calculate the thermal stability parameters of the thread grease material by measuring the mass change at different temperatures, including the peak temperature and peak height of the weight loss peak.

8. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 2, characterized in that: The fastening and unfastening tests shall be performed at least three times.

9. The performance testing method for high-temperature sealing thread grease for oil casing according to any one of claims 1 to 8, characterized in that: The tested high-temperature sealing thread grease has an operating temperature of up to 180℃.

10. The performance testing method for high-temperature sealing thread grease for oil casing according to claim 9, characterized in that: The high-temperature sealing thread grease is used in oil wells, gas wells, or geothermal wells.

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