Method for evaluating gas channeling resistance of ductile material and application thereof

Abstract

This invention discloses a method for evaluating the gas channeling resistance of tough materials. The tough material to be tested is added to a cement-based slurry to prepare a cement slurry. This slurry is poured into a mold and then placed in a cement stone pressurized curing vessel. Channeling gas is introduced into the vessel, and the volume concentration, curing pressure, and curing temperature of the channeling gas are adjusted. Continuous curing is performed for the required time, and the outlet gas flow rate of the cement stone pressurized curing vessel is recorded. The gas channeling resistance of the tough material is evaluated based on the changes in the outlet gas flow rate. This method for evaluating the gas channeling resistance of tough materials can assess the gas channeling resistance of tough materials under different gas types and concentrations, providing a new approach and method for evaluating the long-term sealing integrity of cement stone, and has significant theoretical and practical value.

Description

Technical Field

[0001] This invention relates to a method for evaluating the gas channeling resistance of tough materials and its application. Background Technology

[0002] Energy storage is considered a key element of the 21st-century energy supply chain. It can significantly improve the absorption of renewable energy sources such as photovoltaics and wind power, enhance grid stability, improve the efficiency of the energy system, promote the replacement of fossil fuels with renewable energy, and increase the proportion of renewable energy.

[0003] In the field of gas storage and energy storage, the quality of the anti-gas channeling performance of the toughening materials used in the cementing construction of large-size horizontal wells has a significant impact on the sealing performance, operational safety, and service life of the gas storage facility. Currently, the performance evaluation of toughening materials in preventing gas channeling uses the method in SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5". However, this method can only evaluate the gas channeling performance from a single perspective of the cement paste, which has limitations. Because there are many causes of gas channeling, the evaluation results from a single perspective are incomplete and cannot reflect the sealing integrity of the cement paste or the usability of the toughening materials. Therefore, we must accelerate the research on evaluation methods for high-strength and tough cement materials and conduct research on factors affecting the performance of cement slurry systems to improve production efficiency. Summary of the Invention

[0004] To further optimize the evaluation method for the gas channeling resistance of tough materials and enrich the selection space of evaluation methods, this invention is proposed to provide a highly sensitive evaluation method for the gas channeling resistance of tough materials. The evaluation method for the gas channeling resistance of tough materials provided by this invention involves preparing the tough material into a cement slurry, curing it under certain temperature, pressure, and gas flow conditions, and then evaluating the gas channeling resistance of the tough material based on the gas flow rate passing through the cement paste.

[0005] As one aspect of the present invention, a method for evaluating the gas channeling resistance of a tough material is provided, comprising: adding the tough material to be tested to a cement-based slurry to prepare a cement slurry; pouring the cement slurry into a mold and then placing it into a cement stone pressurized curing vessel; introducing channeling gas into the cement stone pressurized curing vessel; adjusting the volume concentration of the channeling gas in the cement stone pressurized curing vessel; setting the curing pressure and curing temperature; performing continuous curing; recording the outlet gas flow rate of the cement stone pressurized curing vessel; and evaluating the gas channeling resistance of the tough material based on the change in the outlet gas flow rate of the cement stone pressurized curing vessel.

[0006] In a feasible specific embodiment, the cement slurry includes cement and the toughening material, wherein the mass of the toughening material is 1.5 to 7% of the mass of the cement.

[0007] In a feasible specific implementation, the flow rate of the cross-flow gas introduced into the cement stone pressurization curing vessel is 100-1200 mL / min.

[0008] In a feasible specific implementation, the maintenance pressure is 0.1 to 110 MPa.

[0009] In a feasible specific implementation, the curing temperature is 23–150°C.

[0010] In a feasible specific implementation, the continuous maintenance period is 24 hours to 70 days.

[0011] In a feasible specific implementation, the cross-flow gas in the cement stone pressurized curing autoclave is one of hydrogen, helium, carbon dioxide and methane or any combination thereof.

[0012] In a feasible specific implementation, the volume concentration of hydrogen in the cement stone pressurized curing autoclave is 80-99.9%.

[0013] In a feasible specific implementation, the volume concentration of helium in the cement stone pressurization curing vessel is 80-99.9%.

[0014] In a feasible specific implementation, the volume concentration of carbon dioxide in the cement stone pressurized curing autoclave is 50-90%.

[0015] In a feasible specific implementation, the volume concentration of methane in the cement stone pressurized curing kettle is 50-90%.

[0016] As another aspect of the present invention, the application of the evaluation method for the gas channeling prevention performance of the above-mentioned tough materials in the cementing construction of gas storage facilities is discussed.

[0017] The present invention provides a method for evaluating the gas channeling resistance of tough materials, enabling the evaluation of tough material performance under different gas types and concentrations. It simultaneously achieves lateral stress evaluation, longitudinal stress evaluation, and circumferential multi-directional integrity evaluation of cement stone. This invention simultaneously evaluates cement stone from various dimensions, simulating the stress state of the downhole cement sheath and assessing whether the cement stone exhibits good performance under the plastic and elastic changes during injection and production. It effectively evaluates whether micro-gaps are generated after expansion and contraction of the cement stone under multiple stress conditions, creating channels for gas and water channeling. This provides a new approach and method for evaluating whether cement stone can maintain long-term sealing integrity, and has significant theoretical and practical value. Detailed Implementation

[0018] The dimensions of the molds described in the embodiments and comparative examples of this invention are as follows:

[0019] The No. 1 mold has the following characteristics: steel sleeve height 200mm, outer steel sleeve outer diameter 90mm, wall thickness 10mm, inner steel sleeve outer diameter 27.17mm, and annular space clearance 21.415mm.

[0020] The No. 2 mold has the following characteristics: steel sleeve height 200mm, outer steel sleeve outer diameter 80mm, wall thickness 10mm, inner steel sleeve outer diameter 17.17mm, and annular space clearance 21.415mm.

[0021] The No. 3 mold has the following characteristics: steel sleeve height 200mm, outer steel sleeve outer diameter 70mm, wall thickness 10mm, inner steel sleeve outer diameter 7.17mm, and annular space clearance 21.415mm.

[0022] In the embodiments and comparative examples of this invention, the G-grade cement is from Jiahua Cement Plant, the quartz sand is from Chaoyang Minghua Company, the oil well cement dispersant GWD-1S is from Great Wall Drilling Engineering Co., Ltd., the oil well cement fluid loss reducer GWF-200L is from Great Wall Drilling Engineering Co., Ltd., the oil well cement retarder GWR-300L is from Great Wall Drilling Engineering Co., Ltd., the oil well cement defoamer GWX-1L is from Great Wall Drilling, the oil well cement anti-gas channeling agent DRT-100S is from China Petroleum Engineering Technology Research Institute, the oil well cement toughening material DRE-3S is from China Petroleum Engineering Technology Research Institute, and the oil well cement toughening material JXE-3S is from Panjin Hongbo Petrochemical Company.

[0023] Example 1

[0024] Prepare the cement slurry system according to the formula and experimental requirements:

[0025] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0026] Comparison slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L + 1.5% (BWOC) oil well cement anti-gas channeling agent DRT-100S.

[0027] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0028] The anti-gas channeling performance of cement-based slurry and contrast slurry was evaluated using the method specified in SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0029] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry.

[0030] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0031] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0032] Evaluation was performed using the method of the present invention:

[0033] Pour the cement-based slurry and the contrast slurry into mold No. 1, then place them into a cement stone pressure curing autoclave. Introduce helium gas into the cement stone pressure curing autoclave at a flow rate of 250 mL / min. Adjust the volume concentration of helium gas in the cement stone pressure curing autoclave to 99.9%. Adjust the curing pressure of the cement stone pressure curing autoclave to 50 MPa and the curing temperature to 100℃. Curing is carried out continuously for 70 days.

[0034] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 7, 14, 28, 42, 56, and 70 days of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 70 days of curing, and the changes in gas flow rate were recorded. The results are shown in Table 1.

[0035] Table 1:

[0036]

[0037] As can be seen from the test results in Table 1, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0038] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0039] The results obtained by the method of this invention are consistent with the actual situation.

[0040] Example 2

[0041] Prepare the cement slurry system according to the formula and experimental requirements:

[0042] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0043] Comparative slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 7% (BWOC) oil well cement toughening material DRE-3S.

[0044] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0045] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 2 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method of Cement Admixtures for Oil Wells: Part 5".

[0046] Evaluation results: Gas channeling occurred in both cement-based slurry and contrast slurry.

[0047] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0048] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0049] Evaluation was performed using the method of the present invention:

[0050] The cement-based slurry and the contrast slurry were poured into mold No. 2, and then placed into a cement stone pressure curing kettle. Hydrogen gas was introduced into the cement stone pressure curing kettle at a flow rate of 1200 mL / min. The volume concentration of hydrogen gas in the cement stone pressure curing kettle was adjusted to 90%. The curing pressure of the cement stone pressure curing kettle was adjusted to 31.5 MPa and the curing temperature to 63℃. The curing was carried out continuously for 7 days.

[0051] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 2, 3, 4, 5, 6 and 7 days of curing were measured by a gas flow meter; the sealing integrity of the cement ring in the mold after 7 days of curing was observed and the changes in gas flow rate were recorded; the results are shown in Table 2.

[0052] Table 2:

[0053]

[0054] As can be seen from the test results in Table 2, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0055] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0056] The results obtained by the method of this invention are consistent with the actual situation.

[0057] Example 3

[0058] Prepare the cement slurry system according to the formula and experimental requirements:

[0059] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0060] Comparison slurry: 500g G grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 3% (BWOC) oil well cement toughening material JXE-3S.

[0061] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0062] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 3 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0063] Evaluation results: No gas channeling occurred in either the cement-based slurry or the control slurry.

[0064] It was observed that there were no micro-gaps in the cement stone after curing of both cement-based slurry and contrast slurry, indicating that no air channeling actually occurred in the cement-based slurry and contrast slurry.

[0065] The evaluation results are consistent with the actual situation.

[0066] Evaluation was performed using the method of the present invention:

[0067] Pour the cement-based slurry and the contrast slurry into mold No. 3, then place them into a cement stone pressure curing autoclave. Introduce carbon dioxide into the cement stone pressure curing autoclave at a flow rate of 100 mL / min. Adjust the volume concentration of carbon dioxide in the cement stone pressure curing autoclave to 50%. Adjust the curing pressure of the cement stone pressure curing autoclave to 0.1 MPa and the curing temperature to 23℃. Curing is carried out continuously for 24 hours.

[0068] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 2, 4, 8, 12, 16, 20 and 24 hours of curing were measured using a gas flow meter. The sealing integrity of the cement ring in the mold after 24 hours of curing was observed and the changes in gas flow rate were recorded. The results are shown in Table 3.

[0069] Table 3:

[0070]

[0071] As shown in Table 3, the flow rate of helium gas through the cement stone was 0 for both the cement-based slurry and the control slurry in this embodiment as the curing time increased, indicating that no gas channeling occurred in either the cement-based slurry or the control slurry in this embodiment.

[0072] In this embodiment, the cement rings inside the mold after curing of both the cement-based slurry and the control slurry showed no micro-gaps, indicating that no gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0073] The results obtained by the method of this invention are consistent with the actual situation.

[0074] Example 4

[0075] Prepare the cement slurry system according to the formula and experimental requirements:

[0076] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0077] Comparison slurry: 500g G grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 5% (BWOC) oil well cement toughening material DRE-3S.

[0078] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0079] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 4 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0080] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry.

[0081] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0082] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0083] Evaluation was performed using the method of the present invention:

[0084] Pour the cement-based slurry and the contrast slurry into mold No. 3, then place them into a cement stone pressure curing autoclave. Introduce helium into the cement stone pressure curing autoclave at a flow rate of 600 mL / min. Adjust the volume concentration of helium in the cement stone pressure curing autoclave to 80%. Adjust the curing pressure of the cement stone pressure curing autoclave to 110 MPa and the curing temperature to 150℃. Curing is carried out continuously for 28 days.

[0085] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 2, 4, 7, 14, 21, and 28 days of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 28 days of curing, and the changes in gas flow rate were recorded. The results are shown in Table 4.

[0086] Table 4:

[0087]

[0088] As can be seen from the test results in Table 4, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0089] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0090] The results obtained by the method of this invention are consistent with the actual situation.

[0091] Example 5

[0092] Prepare the cement slurry system according to the formula and experimental requirements:

[0093] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0094] Comparison slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L + 7% (BWOC) oil well cement toughening material JXE-3S.

[0095] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0096] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 5 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0097] Evaluation results: No gas channeling occurred in either the cement-based slurry or the control slurry.

[0098] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0099] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0100] Evaluation was performed using the method of the present invention:

[0101] Pour the cement-based slurry and the contrast slurry into mold No. 1, then place them into a cement stone pressure curing kettle. Introduce methane into the cement stone pressure curing kettle at a flow rate of 1000 mL / min. Adjust the volume concentration of methane in the cement stone pressure curing kettle to 90%. Adjust the curing pressure of the cement stone pressure curing kettle to 20 MPa and the curing temperature to 40℃. Curing is carried out continuously for 48 hours.

[0102] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 2, 6, 12, 18, 24, 36, and 48 hours of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 48 hours of curing, and the changes in gas flow rate were recorded. The results are shown in Table 5.

[0103] Table 5:

[0104]

[0105] As can be seen from the test results in Table 5, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0106] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0107] The results obtained by the method of this invention are consistent with the actual situation.

[0108] Example 6

[0109] Prepare the cement slurry system according to the formula and experimental requirements:

[0110] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0111] Comparison slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 3% (BWOC) oil well cement anti-gas channeling agent DRT-100S.

[0112] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0113] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 6 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0114] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry;

[0115] However, it was observed that both cement-based slurry and contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and contrast slurry.

[0116] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0117] Evaluation was performed using the method of the present invention:

[0118] Pour the cement-based slurry and the contrast slurry into mold No. 2, then place them into a cement stone pressure curing kettle. Introduce hydrogen gas into the cement stone pressure curing kettle at a flow rate of 500 mL / min. Adjust the volume concentration of hydrogen gas in the cement stone pressure curing kettle to 90%. Adjust the curing pressure of the cement stone pressure curing kettle to 60 MPa and the curing temperature to 120℃. Curing is carried out continuously for 14 days.

[0119] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 2, 4, 6, 8, 10, 12 and 14 days of curing were measured by a gas flow meter; the sealing integrity of the cement ring in the mold after 14 days of curing was observed and the changes in gas flow rate were recorded; the results are shown in Table 6.

[0120] Table 6:

[0121]

[0122] As can be seen from the test results in Table 6, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0123] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0124] The results obtained by the method of this invention are consistent with the actual situation.

[0125] Example 7

[0126] Prepare the cement slurry system according to the formula and experimental requirements:

[0127] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0128] Comparison slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 7% (BWOC) oil well cement anti-gas channeling agent DRT-100S.

[0129] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0130] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 7 was evaluated using the method in "SY / T 5504.5-2022 Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0131] Evaluation results: No gas channeling occurred in either the cement-based slurry or the control slurry.

[0132] However, it was observed that both the cement-based slurry and the contrast slurry had tiny micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0133] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0134] Evaluation was performed using the method of the present invention:

[0135] Pour the cement-based slurry and the contrast slurry into mold No. 1, then place them into a cement stone pressure curing kettle. Introduce carbon dioxide into the cement stone pressure curing kettle at a flow rate of 100 mL / min. Adjust the volume concentration of carbon dioxide in the cement stone pressure curing kettle to 90%. Adjust the curing pressure of the cement stone pressure curing kettle to 80 MPa and the curing temperature to 120℃. Curing is carried out continuously for 7 days.

[0136] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 2, 3, 4, 5, 6 and 7 days of curing were measured using a gas flow meter; the sealing integrity of the cement ring in the mold after 7 days of curing was observed and the changes in gas flow rate were recorded; the results are shown in Table 7.

[0137] Table 7:

[0138]

[0139] As can be seen from the test results in Table 7, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0140] In this embodiment, both the cement-based slurry and the control slurry had tiny micro-gaps in the cement ring inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0141] The results obtained by the method of this invention are consistent with the actual situation.

[0142] Example 8

[0143] Prepare the cement slurry system according to the formula and experimental requirements:

[0144] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0145] Comparison slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L + 1.5% (BWOC) oil well cement toughening material JXE-3S.

[0146] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0147] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 8 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0148] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry.

[0149] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0150] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0151] Evaluation was performed using the method of the present invention:

[0152] The cement-based slurry and the contrast slurry were poured into mold No. 3, and then placed into a cement stone pressure curing kettle. Hydrogen gas was introduced into the cement stone pressure curing kettle at a flow rate of 800 mL / min. The volume concentration of hydrogen gas in the cement stone pressure curing kettle was adjusted to 99.9%. The curing pressure of the cement stone pressure curing kettle was adjusted to 10 MPa and the curing temperature to 30℃. The curing was carried out continuously for 70 days.

[0153] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 7, 14, 28, 42, 56, and 70 days of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 70 days of curing, and the changes in gas flow rate were recorded. The results are shown in Table 8.

[0154] Table 8:

[0155]

[0156] As can be seen from the test results in Table 8, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0157] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0158] The results obtained by the method of this invention are consistent with the actual situation.

[0159] Example 9

[0160] Prepare the cement slurry system according to the formula and experimental requirements:

[0161] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0162] Comparative slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 1.5% (BWOC) oil well cement toughening material DRE-3S.

[0163] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0164] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 9 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0165] Evaluation results: Gas channeling occurred in both cement-based slurry and contrast slurry.

[0166] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0167] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0168] Evaluation was performed using the method of the present invention:

[0169] Pour the cement-based slurry and the contrast slurry into mold No. 1, then place them into a cement stone pressure curing kettle. Introduce methane into the cement stone pressure curing kettle at a flow rate of 1000 mL / min. Adjust the volume concentration of methane in the cement stone pressure curing kettle to 50%. Adjust the curing pressure of the cement stone pressure curing kettle to 30 MPa and the curing temperature to 60℃. Curing is carried out continuously for 14 days.

[0170] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 2, 4, 6, 8, 10, 12, and 14 days of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 14 days of curing, and the changes in gas flow rate were recorded. The results are shown in Table 9.

[0171] Table 9:

[0172]

[0173] As can be seen from the test results in Table 9, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0174] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0175] The results obtained by the method of this invention are consistent with the actual situation.

[0176] Example 10

[0177] Prepare the cement slurry system according to the formula and experimental requirements:

[0178] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0179] Comparison slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 5% (BWOC) oil well cement toughening material JXE-3S.

[0180] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0181] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 10 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0182] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry.

[0183] However, it was observed that both the cement-based slurry and the contrast slurry had tiny micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0184] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0185] Evaluation was performed using the method of the present invention:

[0186] Pour the cement-based slurry and the contrast slurry into mold No. 2, then place them into a cement stone pressure curing kettle. Introduce carbon dioxide into the cement stone pressure curing kettle at a flow rate of 250 mL / min. Adjust the volume concentration of carbon dioxide in the cement stone pressure curing kettle to 70%. Adjust the curing pressure of the cement stone pressure curing kettle to 110 MPa and the curing temperature to 150℃. Curing is carried out continuously for 28 days.

[0187] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 2, 4, 7, 14, 21, and 28 days of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 28 days of curing, and the changes in gas flow rate were recorded. The results are shown in Table 10.

[0188] Table 10:

[0189]

[0190] As can be seen from the test results in Table 10, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0191] In this embodiment, both the cement-based slurry and the control slurry had tiny micro-gaps in the cement ring inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0192] The results obtained by the method of this invention are consistent with the actual situation.

[0193] Example 11

[0194] Prepare the cement slurry system according to the formula and experimental requirements:

[0195] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0196] Comparative slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 3% (BWOC) oil well cement toughening material DRE-3S.

[0197] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0198] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 11 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0199] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry.

[0200] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0201] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0202] Evaluation was performed using the method of the present invention:

[0203] The cement-based slurry and the contrast slurry were poured into mold No. 2, and then placed into a cement stone pressure curing autoclave. Helium gas was introduced into the cement stone pressure curing autoclave at a flow rate of 1200 mL / min. The volume concentration of helium gas in the cement stone pressure curing autoclave was adjusted to 90%. The curing pressure of the cement stone pressure curing autoclave was adjusted to 0.1 MPa and the curing temperature to 23℃. The autoclave was continuously cured for 48 hours.

[0204] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 2, 6, 12, 18, 24, 36, and 48 hours of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 48 hours of curing, and the changes in gas flow rate were recorded. The results are shown in Table 11.

[0205] Table 11:

[0206]

[0207] As can be seen from the test results in Table 11, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0208] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0209] The results obtained by the method of this invention are consistent with the actual situation.

[0210] Example 12

[0211] Prepare the cement slurry system according to the formula and experimental requirements:

[0212] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0213] Comparison slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 5% (BWOC) oil well cement anti-gas channeling agent DRT-100S.

[0214] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0215] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 12 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method of Cement Admixtures for Oil Wells: Part 5".

[0216] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry.

[0217] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0218] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0219] Evaluation was performed using the method of the present invention:

[0220] Pour the cement-based slurry and the contrast slurry into mold No. 3, then place them into a cement stone pressure curing kettle. Introduce methane into the cement stone pressure curing kettle at a flow rate of 500 mL / min. Adjust the volume concentration of methane in the cement stone pressure curing kettle to 70%. Adjust the curing pressure of the cement stone pressure curing kettle to 40 MPa and the curing temperature to 80℃. Curing is carried out continuously for 7 days.

[0221] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 2, 3, 4, 5, 6 and 7 days of curing were measured by a gas flow meter; the sealing integrity of the cement ring in the mold after 7 days of curing was observed and the changes in gas flow rate were recorded; the results are shown in Table 12.

[0222] Table 12:

[0223]

[0224] As can be seen from the test results in Table 12, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0225] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0226] The results obtained by the method of this invention are consistent with the actual situation.

[0227] Example 13

[0228] Prepare the cement slurry system according to the formula and experimental requirements:

[0229] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0230] Comparative slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 1.5% (BWOC) oil well cement toughening material DRE-3S.

[0231] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0232] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 13 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0233] Evaluation results: Gas channeling occurred in both cement-based slurry and contrast slurry.

[0234] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0235] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0236] Evaluation was performed using the method of the present invention:

[0237] The cement-based slurry and the contrast slurry were poured into mold No. 1, and then placed into a cement stone pressure curing kettle. Carbon dioxide was introduced into the cement stone pressure curing kettle at a flow rate of 1000 mL / min. The volume concentration of carbon dioxide in the cement stone pressure curing kettle was adjusted to 80%. The curing pressure of the cement stone pressure curing kettle was adjusted to 31.5 MPa and the curing temperature to 63℃. The curing was carried out continuously for 70 days.

[0238] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 7, 14, 28, 42, 56, and 70 days of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 70 days of curing, and the changes in gas flow rate were recorded. The results are shown in Table 13.

[0239] Table 13:

[0240]

[0241] As can be seen from the test results in Table 13, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0242] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0243] The results obtained by the method of this invention are consistent with the actual situation.

[0244] Example 14

[0245] Prepare the cement slurry system according to the formula and experimental requirements:

[0246] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0247] Comparison slurry: 500g G-grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 7% (BWOC) oil well cement anti-gas channeling agent DRT-100S.

[0248] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0249] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 14 was evaluated using the method in "SY / T 5504.5-2022 Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0250] Evaluation results: No gas channeling occurred in either the cement-based slurry or the control slurry.

[0251] However, it was observed that both the cement-based slurry and the contrast slurry had tiny micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0252] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0253] Evaluation was performed using the method of the present invention:

[0254] Pour the cement-based slurry and the contrast slurry into mold No. 2, then place them into a cement stone pressure curing autoclave. Introduce hydrogen gas into the cement stone pressure curing autoclave at a flow rate of 200 mL / min. Adjust the volume concentration of hydrogen gas in the cement stone pressure curing autoclave to 80%. Adjust the curing pressure of the cement stone pressure curing autoclave to 80 MPa and the curing temperature to 140℃. Curing is carried out continuously for 24 hours.

[0255] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 2, 4, 8, 12, 16, 20 and 24 hours of curing were measured using a gas flow meter. The sealing integrity of the cement ring in the mold was observed after 24 hours of curing, and the changes in gas flow rate were recorded. The results are shown in Table 14.

[0256] Table 14:

[0257]

[0258] As can be seen from the test results in Table 14, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0259] In this embodiment, both the cement-based slurry and the control slurry had tiny micro-gaps in the cement ring inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0260] The results obtained by the method of this invention are consistent with the actual situation.

[0261] Example 15

[0262] Prepare the cement slurry system according to the formula and experimental requirements:

[0263] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0264] Comparison slurry: 500g G grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 3% (BWOC) oil well cement toughening material JXE-3S.

[0265] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0266] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 15 was evaluated using the method of SY / T 5504.5-2022 "Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0267] Evaluation results: Gas channeling occurred in both cement-based slurry and contrast slurry.

[0268] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0269] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0270] Evaluation was performed using the method of the present invention:

[0271] Pour the cement-based slurry and the contrast slurry into mold No. 1, then place them into a cement stone pressure curing autoclave. Introduce helium into the cement stone pressure curing autoclave at a flow rate of 800 mL / min, adjust the volume concentration of helium in the cement stone pressure curing autoclave to 85%, adjust the curing pressure of the cement stone pressure curing autoclave to 70 MPa and the curing temperature to 150℃, and cure continuously for 14 days.

[0272] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 2, 4, 6, 8, 10, 12 and 14 days of curing were measured by a gas flow meter; the sealing integrity of the cement ring in the mold after 14 days of curing was observed and the changes in gas flow rate were recorded; the results are shown in Table 15.

[0273] Table 15:

[0274]

[0275] As can be seen from the test results in Table 15, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0276] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0277] The results obtained by the method of this invention are consistent with the actual situation.

[0278] Example 16

[0279] Prepare the cement slurry system according to the formula and experimental requirements:

[0280] Cement-based slurry: 500g of Grade G cement + 300g of quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g of oil well cement defoamer GWX-1L.

[0281] Comparison slurry: 500g G grade cement + 300g quartz sand + 10% (BWOC) oil well cement dispersant GWD-1S + 3.5% (BWOC) oil well cement fluid loss reducer GWF-200L + 4% (BWOC) oil well cement retarder GWR-300L + 42% distilled water (BWOC) + 1.6g oil well cement defoamer GWX-1L + 5% (BWOC) oil well cement toughening material DRE-3S.

[0282] In the above formula, BWOC represents: the mass fraction of the grade G cement, calculated based on 100% of the mass of the grade G cement.

[0283] The anti-gas channeling performance of the cement-based slurry and the control slurry of Example 16 was evaluated using the method in "SY / T 5504.5-2022 Evaluation Method for Cement Admixtures in Oil Wells: Part 5".

[0284] Evaluation results: Gas channeling occurred in the cement-based slurry, while no gas channeling occurred in the control slurry.

[0285] However, it was observed that both the cement-based slurry and the contrast slurry had obvious micro-gaps after curing, indicating that gas channeling actually occurred in the cement-based slurry and the contrast slurry.

[0286] The discrepancy between the evaluation results and the actual situation indicates that the evaluation method is flawed.

[0287] Evaluation was performed using the method of the present invention:

[0288] The cement-based slurry and the contrast slurry were poured into mold No. 3, and then placed into a cement stone pressure curing kettle. Methane was introduced into the cement stone pressure curing kettle at a flow rate of 250 mL / min. The volume concentration of methane in the cement stone pressure curing kettle was adjusted to 80%. The curing pressure of the cement stone pressure curing kettle was adjusted to 60 MPa and the curing temperature to 120℃. The curing was carried out continuously for 28 days.

[0289] The initial flow rate at the gas outlet and the gas flow rate through the cement stone after 1, 2, 4, 7, 14, 21, and 28 days of curing were measured using a gas flow meter. The sealing integrity of the cement ring inside the mold was observed after 28 days of curing, and the changes in gas flow rate were recorded. The results are shown in Table 16.

[0290] Table 16:

[0291]

[0292] As can be seen from the test results in Table 16, the flow rate of helium gas through the cement stone increased with the increase of curing time in both the cement-based slurry and the control slurry in this embodiment, indicating that gas channeling occurred in both the cement-based slurry and the control slurry in this embodiment.

[0293] In this embodiment, both the cement-based slurry and the control slurry showed obvious micro-gaps in the cement rings inside the mold after curing, indicating that gas channeling actually occurred in the cement-based slurry and the control slurry in this embodiment.

[0294] The results obtained by the method of this invention are consistent with the actual situation.

Claims

1. A method for evaluating the gas channeling resistance of tough materials, characterized in that, include: The toughness material to be tested is added to the cement-based slurry to prepare a cement slurry. The cement slurry is poured into a mold and then placed in a cement stone pressurized curing vessel. Cross-flow gas is introduced into the cement stone pressurized curing vessel, and the volume concentration of the cross-flow gas in the cement stone pressurized curing vessel is adjusted. The curing pressure and curing temperature are set, and continuous curing is carried out. The outlet gas flow rate of the cement stone pressurized curing vessel is recorded. The anti-gas cross-flow performance of the toughness material is evaluated based on the change in the outlet gas flow rate.

2. The method for evaluating the gas channeling resistance of the tough material according to claim 1, characterized in that, The cement slurry includes cement and the toughening material, wherein the mass of the toughening material is 1.5 to 7% of the mass of the cement.

3. The method for evaluating the anti-gas channeling performance of the tough material according to claim 1, wherein the flow rate of the channeling gas introduced into the cement stone pressurized curing vessel is 100-1200 mL / min.

4. The method for evaluating the gas channeling resistance of the tough material according to claim 1, characterized in that, The curing pressure is 0.1–110 MPa, the curing temperature is 23–150°C, and the continuous curing time is 24 hours to 70 days.

5. The method for evaluating the gas channeling resistance of the tough material according to claim 1, wherein the channeling gas in the cement stone pressurized curing autoclave is one or any combination of hydrogen, helium, carbon dioxide and methane.

6. The method for evaluating the gas channeling resistance of the tough material according to claim 5, characterized in that, The volume concentration of hydrogen in the cement stone pressurized curing autoclave is 80-99.9%.

7. The method for evaluating the gas channeling resistance of the tough material according to claim 5, characterized in that, The volume concentration of helium in the cement stone pressurized curing autoclave is 80-99.9%.

8. The method for evaluating the gas channeling resistance of the tough material according to claim 5, characterized in that, The volume concentration of carbon dioxide in the cement stone pressurized curing autoclave is 50-90%.

9. The method for evaluating the gas channeling resistance of the tough material according to claim 5, characterized in that, The volume concentration of methane in the cement stone pressurized curing autoclave is 50-90%.

10. The application of the evaluation method for the gas channeling prevention performance of tough materials in gas storage well cementing construction, characterized in that... The method for evaluating the gas channeling resistance of the tough material is the same as the method for evaluating the gas channeling resistance of the tough material according to any one of claims 1-9.

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