A method for pipeline cleaning and grouting

Abstract

This invention discloses a pipeline cleaning and grouting construction method. First, the grouting pit is excavated and supported. Then, a combined pipeline cleaning tool is used for physical cleaning 1-3 times, followed by chemical cleaning 1-3 times, and water cleaning 1-3 times. Finally, pipeline grouting is performed. This invention uses a grouting pump with a high-pressure connection for grouting, achieving a long grouting distance and high grouting density (approximately 7 kilometers). A water-push ball process is used to further increase the grouting density. The grouting material ratio is coordinated with the grouting pressure, and the initial grouting time coincides with the setting time of the grouting material, ensuring both the flow of the grouting material within the pipeline and timely solidification.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas pipeline waste treatment technology, specifically relating to a pipeline cleaning and grouting construction method. Background Technology

[0002] With the rapid development of the petroleum industry in my country, new pipelines are constantly being built and put into actual production and operation.

[0003] After long-term operation, oil and gas pipelines and their surrounding environments become complex, making it difficult to guarantee the reliability of pipeline abandonment construction. Environmental changes also significantly impact construction. While traditional open-cut pipeline disposal methods can remove the pipeline and eliminate safety hazards, the sheer volume of above-ground equipment and building demolition, coupled with the complexity of underground pipeline handling, presents significant challenges. For abandoned pipelines passing through above-ground buildings or farmland, in-situ disposal is more reasonable. Grouting and solidification is a commonly used in-situ pipeline abandonment technique, with key aspects focusing on pipe cleaning and internal filling. Optimizing the cleaning and filling processes based on the actual pipeline conditions, as well as selecting the best grouting system, is crucial for ensuring effective grouting and solidification. Existing methods using air compressors for grouting suffer from insufficient grout density and short grouting distances (approximately 1 kilometer). Summary of the Invention

[0004] The purpose of this invention is to provide a pipeline cleaning and grouting construction method.

[0005] A pipeline cleaning and grouting construction method is carried out according to the following steps:

[0006] (1) Grouting operation pit excavation and support: After the grouting operation pit is excavated, the pipe is cut by cold cutting, the grouting point is sealed with a cap, the exhaust inspection point is welded with a thick blind plate, and grouting holes and exhaust holes are installed on the top of the pipe; the foundation pit is excavated by slope to ensure the formation of the pipe trench, and steel sheet pile support is set.

[0007] (2) Pipeline cleaning: First, use a combination pipe cleaner to physically clean the pipe 1-3 times, then use chemical cleaning 1-3 times, and finally use water cleaning 1-3 times.

[0008] (3) Pipeline grouting: Select grouting points at an average interval of 1.5-2.5 km / s and perform grouting at each point. The grouting volume of the grouting pump is 15-25 m³ / s. 3 / h, once grouting begins in each section, it cannot be stopped until the grouting is completed. Air inside the pipeline is vented through the vent hole at the vent checkpoint to ensure that the cement slurry can completely fill the pipeline. When the grouting fluid pushes the pig to the checkpoint, the vent valve is closed, the mud pump is shut down, and the grouting work for this section is completed.

[0009] The thickness of the thick blind plate is 6-10mm.

[0010] When the work pit is being excavated in farmland, the topsoil at a depth of 0.3-0.7m from the work pit location should be stripped off and stored separately before excavation. The stripped soil should then be piled together and covered with tarpaulin.

[0011] The physical pigging process uses nitrogen gas to push the spool, with a vaporizer displacement of 1200-1800 m³ / h. 3 The nitrogen pushing pressure is approximately 0.4-0.8 MPa per hour.

[0012] The chemical cleaning process involves inserting two pigging balls at a time. The first ball is inserted into the old pipeline, while the second remains at the pipe opening. The cleaning agent is injected under pressure. The distance between the two pigging balls is required to be 8-12m, forming a cleaning system consisting of pigging balls, cleaning agent, and pigging balls. Nitrogen gas is used to drive the pigging device to begin cleaning, with the nitrogen-driven pigging ball operating at a speed of 2-3 km / h.

[0013] The cleaning agent is composed of the following components in parts by weight: 10-30 parts of 3-amino-1-hexanol, 10-30 parts of polyepoxysuccinic acid, 3-5 parts of sodium lignosulfonate, 3-5 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 0.5-1.5 parts of sodium hydroxide, and 500-800 parts of water.

[0014] The equipment used for pipeline grouting consists of a mixing tank, a storage tank, a grouting pump, and a water tank. The grouting material is transported to the site by bulk trucks. During the grouting process, one vehicle for transporting bulk cement and fly ash must be kept on standby, and one water supply truck must be provided to ensure that the grouting work can be carried out without interruption.

[0015] The grouting fluid is made by mixing grouting material and water in a mixing tank. The mass ratio of grouting material to water is 2:1. After mixing, the mixture is sent to a storage tank for later use.

[0016] The grouting material is composed of the following components in parts by weight: 40-100 parts fly ash, 5-20 parts cement, 1-3 parts alum stone powder, 1-3 parts styrene-butadiene-styrene block copolymer, 3-5 parts vinyl silicone oil, and 3-5 parts 1-adamantane ethylamine.

[0017] The beneficial effects of this invention are as follows: This invention uses a grouting pump and a high-pressure connection for grouting, resulting in a long grouting distance and high grouting density. The grouting distance is approximately 7 kilometers. The use of a water-push ball process further increases the grouting density. The ratio of the grouting material is coordinated with the grouting pressure, and the initial grouting time coincides with the setting time of the grouting material, which not only allows the grouting material to flow in the pipeline but also achieves the effect of timely setting. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0019] Example 1

[0020] A pipeline cleaning and grouting construction method is carried out according to the following steps:

[0021] (1) Grouting pit excavation and support: After the grouting pit is excavated, the pipe is cut by cold cutting. The grouting point is sealed with a cap. The exhaust inspection point is welded with an 8mm thick blind plate. Grouting holes and exhaust holes are installed on the top of the pipe. The pit is excavated by slope to ensure the formation of the pipe trench and is supported by steel sheet piles. When the pit is operated in farmland, the top 0.5m of the topsoil at the pit location is stripped and stored separately before excavation to prevent the restoration of the landform from affecting the growth of crops later. The stripped soil is piled together and covered with tarpaulin to prevent dust pollution. The pit is excavated after the topsoil is stripped. Since the pipeline to be treated has reached the end of its service life, it can be excavated in one go by equipment. The excavation depth is determined according to the pipeline burial depth. Construction should be carried out at the shallowest possible location.

[0022] (2) Pipeline cleaning: First, use a combination pipe cleaner to physically clean the pipe twice, then use chemical cleaning twice, and finally use water cleaning twice.

[0023] Physical cleaning mainly involves removing residual oil from the remaining pipelines. During physical cleaning, nitrogen is used to push the buoy, with a vaporizer displacement of approximately 1500 m³ / h and a nitrogen pushing pressure of 0.6 MPa. If only a small amount of residual oil remains in the pipeline after two cleanings, the cleaning is considered successful. If a large amount of residual oil remains, the cleaning process needs to be repeated to ensure the cleanliness of the pipeline. Once the oil in the pipeline is successfully cleaned, the next step of pipeline cleaning can be carried out.

[0024] The chemical cleaning process involves inserting two pigging balls at a time. The first ball is inserted into the old pipeline, while the second remains at the pipe opening. Cleaning agent is injected under pressure, with a 10m distance between the two pigging balls, forming a cleaning system of pigging balls + cleaning agent + pigging balls. Nitrogen gas is used to propel the pigging device, with a nitrogen-driven pigging speed of 2.5 km / h. The cleaning agent consists of the following components by weight: 20 parts 3-amino-1-hexanol, 20 parts polyepoxysuccinic acid, 4 parts sodium lignosulfonate, 4 parts 2-phosphonobutane-1,2,4-tricarboxylic acid, 1 part sodium hydroxide, and 600 parts water. The cleaning agent reacts fully with the oil adhering to the pipe wall inside the pipeline. Finally, at the pigging recovery point, a tanker truck collects the residual cleaning liquid. Before recovery, a geomembrane is laid around the recovery point to prevent the residual cleaning liquid from polluting the surrounding environment. After removing the pigging balls, this process is repeated at the starting point for a second chemical cleaning. After both cleanings are completed, the next step is performed.

[0025] The pipeline water cleaning and chemical cleaning methods are the same. Two cleaning balls are pushed in at one time. The first cleaning ball is pushed into the old pipeline, and the second cleaning ball is left at the pipe opening. Water is injected under pressure. The two cleaning balls are required to be 10m apart to form a cleaning system of cleaning balls + water + cleaning balls. Nitrogen gas is used to push the cleaning balls to start cleaning. After two chemical cleanings and two water cleanings are completed, the cleaning effect is observed at the ball collection cylinder. The purpose is to clean the oil and chemical cleaning agents adhering to the inner wall of the pipeline. The number of cleanings is determined based on the observation. If it is not up to standard, the above water cleaning system is continued until it is up to standard.

[0026] All oily wastewater and chemical cleaning oily wastewater generated during the cleaning process will be collected and transported to a professional hazardous waste treatment station for treatment. They must not be discharged at will. Oily wastewater will be collected in a collection pool on site and connected to an oil pipe. For areas prone to oil leakage, impermeable cloth will be laid on the ground to prevent leaked oil from seeping into the ground. Oil collection basins and oil-absorbing mats will be prepared in the surrounding area for emergency use.

[0027] The qualification standards for pipeline cleaning are as follows: visual inspection shows that the pipe wall is free of oil, wax, and liquid accumulation; the concentration of combustible gas is less than 10% of the lower explosive limit (LEL), and the old pipeline has been cleaned; the inner wall of the pipeline is inspected and verified, and excavation and pipe cutting are used for inspection as needed.

[0028] (3) Pipeline grouting: After pipeline cleaning, to prevent the accumulation of oil and gas in the abandoned pipelines and the resulting safety accidents, the entire cleaned pipeline is grouted. After grouting, pipelines crossing rivers or ditches are cut and dismantled. Based on the overall site survey and understanding of the terrain, grouting points are selected at an average of 2.0 km / s, and grouting is carried out separately. The equipment used for pipeline grouting consists of a mixing tank, a storage tank, a grouting pump, and a water tank. The grouting material is transported to the site by bulk trucks. During the grouting process, trucks transporting bulk cement and fly ash are also used. One vehicle must be kept on standby, and one water supply vehicle must be provided to ensure that the grouting work can be carried out without interruption. The grouting fluid is made by mixing grouting material and water in a mixing tank (the mass ratio of grouting material to water is 2:1), and then sending it to a storage tank. The grouting pump has a grouting capacity of 20 m3 / h. Once the grouting of each section begins, it cannot be stopped until the grouting is completed. The air inside the pipeline is vented through the vent hole at the vent checkpoint to ensure that the cement slurry can completely fill the pipeline. When the grouting fluid pushes the pipeline pig to the checkpoint, the vent valve is closed, the mud pump is shut down, and the grouting work of this section is completed.

[0029] The grouting material is composed of the following components in parts by weight: 40-100 parts fly ash, 5-20 parts cement, 1-3 parts alum stone powder, 1-3 parts styrene-butadiene-styrene block copolymer, 3-5 parts vinyl silicone oil, and 3-5 parts 1-adamantane ethylamine.

[0030] The starting point of each grouting pipe section is sealed with a thick blind flange. The grouting pump injects grout into the abandoned pipe, pushing the rubber cup to expel air from the pipe. This method ensures that the grouting is dense, and after the grout solidifies, it achieves a sealing effect. This construction method is relatively simple to operate, fast to construct, and safe to construct; moreover, it has a good sealing effect and can completely remediate abandoned pipelines.

[0031] Example 2: Performance Test of Cleaning Agent

[0032] Nine pipeline sections were selected for simulated pipeline cleaning, with each section spaced 2km apart. They were randomly divided into three groups, the same as the grouting points, to facilitate the detection of the cleaning effect. Physical cleaning was performed first, followed by two chemical cleanings. The cleaning equipment and steps were the same as in Example 1. Finally, the cleaning effect was detected.

[0033] The first group uses a cleaning agent with the following components: 20 parts of 3-amino-1-hexanol, 20 parts of polyepoxysuccinic acid, 4 parts of sodium lignosulfonate, 4 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 1 part of sodium hydroxide, and 600 parts of water.

[0034] The second group uses a cleaning agent with the following components: 40 parts of 3-amino-1-hexanol, 4 parts of sodium lignosulfonate, 4 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 1 part of sodium hydroxide, and 600 parts of water.

[0035] The third group uses a cleaning agent with the following components: 40 parts polyepoxysuccinic acid, 4 parts sodium lignosulfonate, 4 parts 2-phosphonobutane-1,2,4-tricarboxylic acid, 1 part sodium hydroxide, and 600 parts water.

[0036] The oil removal rate is calculated based on the amount of oil removed and the amount of oil remaining. The calculation formula is as follows:

[0037] Oil removal rate = (mass of oil removed) / (mass of oil removed + mass of remaining oil) × 100%.

[0038] Statistical analysis was performed using SPSS 24.0 software. The results of the quantitative data were analyzed using... ±s (mean ± standard deviation) indicates that the normality of the data was tested using the Kolmogorov-Smirnov test. For normally distributed data, the difference between the means of two groups was compared using the t-test, and P < 0.05 was considered statistically significant.

[0039] The results are shown in Table 1:

[0040] Table 1

[0041]

[0042] Note: * indicates that the p value is less than 0.05 compared with the first group.

[0043] Example 3: Performance Determination of Grouting Fluid

[0044] The first group uses grouting material with the following components: 70 parts fly ash, 15 parts cement, 2 parts alum powder, 2 parts styrene-butadiene-styrene block copolymer, 4 parts vinyl silicone oil, and 4 parts 1-adamantane ethylamine. The grouting solution is made by mixing the grouting material with water in a mixing tank (the mass ratio of grouting material to water is 2:1).

[0045] The second group uses grouting material with the following components: 70 parts fly ash, 15 parts cement, 4 parts alum powder, 4 parts vinyl silicone oil, and 4 parts 1-adamantane ethylamine. The grouting solution is made by mixing the grouting material with water in a mixing tank (the mass ratio of grouting material to water is 2:1).

[0046] The third group uses grouting material with the following components: 70 parts fly ash, 15 parts cement, 4 parts styrene-butadiene-styrene block copolymer, 4 parts vinyl silicone oil, and 4 parts 1-adamantane ethylamine. The grouting solution is made by mixing the grouting material with water in a mixing tank (the mass ratio of grouting material to water is 2:1).

[0047] The fourth group uses the following grouting material: 70 parts fly ash, 15 parts cement, 2 parts alum powder, 2 parts styrene-butadiene-styrene block copolymer, and 8 parts vinyl silicone oil. The grouting solution is made by mixing the grouting material with water in a mixing tank (the mass ratio of grouting material to water is 2:1).

[0048] The fifth group uses a grouting material with the following components: 70 parts fly ash, 15 parts cement, 2 parts alum powder, 2 parts styrene-butadiene-styrene block copolymer, and 8 parts 1-adamantane ethylamine. The grouting solution is made by mixing the grouting material with water in a mixing tank (the mass ratio of grouting material to water is 2:1).

[0049] Slump refers to the workability of concrete, specifically ensuring proper construction, including the concrete's water retention, fluidity, and cohesiveness. The slump test method is as follows: A slump cone, 100mm at the top, 200mm at the bottom, and 300mm high, is filled with concrete (or grout) and compacted. The cone is then lifted; the concrete (or grout) will collapse due to its own weight. The slump is calculated by subtracting the height of the highest point of the collapsed concrete (or grout) from the cone height (300mm). If the difference is 10mm, the slump is 10. A slump that is too large will cause significant dispersion in the concrete, reducing its strength. Each experiment is repeated 5 times, and the average value is taken.

[0050] The slump test results are shown in Table 2:

[0051] Table 2

[0052]

[0053] Note: * indicates that the p value is less than 0.05 compared with the first group.

[0054] In grouting operations, the hardening and development process of the injected cement grout can be divided into three zones: the fluid zone, the setting transition period, and the solid zone. Therefore, to ensure the success of the grouting operation, the cement grout in the pipeline must not set within the construction time limit (i.e., before the pipeline is fully filled). By adding a retarder, the cement hydration reaction can be delayed, thereby extending the setting time of the cement grout. This allows the newly prepared cement grout to maintain good fluidity for a longer period, facilitating grouting, improving construction efficiency, and at the same time, it will not adversely affect the later properties of the cement grout, ensuring that the pipeline is fully filled and meets the requirements for harmless treatment.

[0055] This invention investigated the effect of the type of retarder on the setting process of cement paste. The experimental results are shown in Table 3 (each experiment was repeated 5 times and the average was taken):

[0056] Table 3

[0057]

[0058] Note: * indicates that the p value is less than 0.05 compared with the first group.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A pipeline cleaning and grouting construction method, characterized in that, Follow these steps: (1) Grouting operation pit excavation and support: After the grouting operation pit is excavated, the pipe is cut by cold cutting, the grouting point is sealed with a cap, the exhaust inspection point is welded with a thick blind plate, and the grouting hole and exhaust hole are installed on the top of the pipe; the foundation pit is excavated by slope to ensure the formation of the pipe trench, and steel sheet pile support is set. (2) Pipeline cleaning: First, use a combination pipe cleaner to physically clean the pipe 1-3 times, then use chemical cleaning 1-3 times, and finally use water cleaning 1-3 times. The chemical cleaning process involves inserting two pigging balls at a time. The first ball is inserted into the old pipeline, while the second ball remains at the pipe opening. The cleaning agent is injected under pressure. The distance between the two pigging balls is required to be 8-12m, forming a cleaning system of pigging balls + cleaning agent + pigging balls. Nitrogen gas is used to push the pigging device to start cleaning, and the nitrogen-push-ball running speed is 2-3 km / h. The cleaning agent is composed of the following components in parts by weight: 10-30 parts of 3-amino-1-hexanol, 10-30 parts of polyepoxysuccinic acid, 3-5 parts of sodium lignosulfonate, 3-5 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid, 0.5-1.5 parts of sodium hydroxide, and 500-800 parts of water. (3) Pipeline grouting: Select grouting points at an average interval of 1.5-2.5 km / s and grout them separately. The grouting pump has a grouting capacity of 15-25 m³ / h. Once the grouting of each section begins, it cannot be stopped until the grouting is completed. Expel the air inside the pipeline through the vent hole at the vent check point so that the cement slurry can completely fill the pipeline. When the grouting fluid pushes the pipeline cleaning tool to the check point, close the vent valve, stop the mud pump, and complete the grouting work of this section. The grouting fluid is made by mixing grouting material and water in a mixing tank until uniform. The mass ratio of grouting material to water is 2:

1. After mixing evenly, it is sent to a storage tank for later use. The grouting material is composed of the following components in parts by weight: 40-100 parts fly ash, 5-20 parts cement, 1-3 parts alum stone powder, 1-3 parts styrene-butadiene-styrene block copolymer, 3-5 parts vinyl silicone oil, and 3-5 parts 1-adamantane ethylamine.

2. The pipeline cleaning and grouting construction method according to claim 1, characterized in that, The thickness of the thick blind plate is 6-10mm.

3. The pipeline cleaning and grouting construction method according to claim 1, characterized in that, When the work pit is being excavated in farmland, the topsoil of 0.3-0.7m above the work pit should be stripped off and stored separately before excavation. The stripped soil should then be piled together and covered with tarpaulin.

4. The pipeline cleaning and grouting construction method according to claim 1, characterized in that, The physical pigging process uses nitrogen to push the buoy, with a vaporizer displacement of approximately 1200-1800 m³ / h and a nitrogen pushing pressure of 0.4-0.8 MPa.

5. The pipeline cleaning and grouting construction method according to claim 1, characterized in that, The equipment used for pipeline grouting consists of a mixing tank, a storage tank, a grouting pump, and a water tank. The grouting material is transported to the site by bulk trucks. During the grouting process, one vehicle for transporting bulk cement and fly ash must be kept on standby, and one water supply truck must be provided to ensure that the grouting work can be carried out without interruption.

Images