Adaptability of large-diameter long-distance oil and gas pipelines without excavation and crossing Zhang Baoqiang 1 Jiao Ruyi 1 Yuan Huizan 2 Zhang Qian 1 Liu Yanli 1 1. China National Petroleum Pipeline Research Institute, Langfang 065000, Hebei; China National Petroleum Pipeline Bureau Emergency Center, Langfang Hebei 065000, Zhang Baoqiang, etc. The adaptability of large-diameter long-distance oil and gas pipelines through trenchless excavation. Oil and gas storage and transportation, 2012, 1 and success or failure. Three types of commonly used large-diameter long-distance oil and gas pipelines, horizontal directional drilling, pipe jacking and shield tunneling, were compared and analyzed from the aspects of geological conditions, crossing length, pipe diameter, pipeline protection and maintenance, construction efficiency, economy and limitations. Limitations and adaptability of traversal methods, and give general selection principles. If the geological conditions are suitable, directional drilling should be preferred, followed by pipe jacking and shielding. If the geology is not suitable for horizontal directional drilling crossing or the crossing distance is short (within 800m) due to the influence of the minimum radius of curvature of the pipeline, the pipe jacking crossing should be selected. When the crossing distance is greater than 800m, a shield is adopted.
In recent years, China has newly constructed large-diameter long-distance oil and gas pipelines with more than 5000km each year. It often uses trenchless crossing methods when crossing rivers. Among them, horizontal directional drilling, pipe jacking and shielding are the three most commonly used trenchless crossings for oil and gas pipelines. Construction methods. Due to the influence of factors such as the complexity of the geological crossing river, construction period and economy, in the actual design and construction process, the adaptability of the trenchless crossing method should be analyzed and analyzed in detail according to the actual situation of the project and the successful cases For comparison, choose the best trenchless crossing method.
When selecting the non-excavation crossing method for large-diameter long-distance oil and gas pipelines, comprehensive consideration should be given to factors such as geological conditions, crossing length, pipe diameter, pipeline protection and maintenance, construction efficiency, economy, and limitations, and the weight of each factor should be clear , To determine the risk assessment system of trenchless crossing method, and finally determine the scientific and reasonable trenchless crossing method.
Engineering practice shows that the adaptability of geological conditions is the most critical factor in the choice of trenchless crossing method for large-diameter long-distance oil and gas pipelines. Directional drilling, pipe jacking and shield tunneling have different adaptability to geological conditions due to different construction techniques, geotechnical cutting and transportation methods, and hole support methods.
Horizontal directional drilling usually adopts the non-excavation crossing method of drill pipe to transmit cutting power, reamer reaming, mud retaining wall and cuttings transportation. When a horizontal directional drilling traverses the rock section of the project about 1 600m, when the insert rock reamer is used to pass through the hard rock section with a uniaxial compressive strength of about 60MPa, each drill pipe takes up to 10h, and the construction speed is very slow. Because the swing of the drill rod in the hole will cause power loss, the cutting torque of the reamer is smaller than the torque of the cutting cutter of the pipe jacking machine and shield machine. Therefore, the 7 horizontal directional drilling is most suitable for clay, sand, and pie. In mud, mudstone, soft rock and other stable formations that are easy to form pores, it is not suitable to pass through gravel layers, pebble layers and broken hard rock layers with a content of more than 50%. Casing isolation, grouting, solidification, opening Measures such as digging, replacing and filling.
Pipe jacking is usually carried out by hydraulic jacking. The pipe jack of the pipe jacking machine cuts the rock and soil, and the pipe jacking well is used as the pressure wall. Each section of pipe is pushed into the soil layer by root according to the design elevation, azimuth and slope until it passes through the terminal. The geological adaptability of pipe jacking is wider than that of directional drilling. It can traverse various complex formations with high water pressure and strong permeability. It can be used in unstable formations and hard formations such as medium coarse sand, gravel, and broken zone that directional drilling is difficult to penetrate. Cross in the rock. However, due to its poor ability to rectify, remove obstacles and deal with accidents than shields, it is not suitable for long-distance excavation in strata with high content of boulders, boulders, and large pebbles.
Shield tunneling equipment is more complex and complete in structure and function than pipe jacking, and has stronger rectification, obstacle clearance and accident handling capabilities. Its geological adaptability is compared to Table 1. Comprehensive construction of horizontal directional drilling, pipe jacking and shield construction in oil and gas pipeline engineering Efficiency crossing method Project name Pipe diameter Pipe length Geological conditions Effective working time / d 24h crossing length / m West second line Weihe crossing medium coarse sand horizontal directional drilling Western second line Hubei Shahe crossing muddy sandstone layer, high rock hardness West second line Sanlitang crossing powder Silty clay and silt The Yitong River rock passes through sandy mudstone, with a maximum pressure of 40 MPa. The east section of the Second West Second Line Nanchang-Shanghai Branch Line Xinganghe Tunnel passes through the silty clay layer. The east section of the Second West Second Line. The Suichuan River passes through gravel sandstone, strong and weathered Rock Qiantang River Shield Project Sand, clay, silty soil with silt Dunzhong County-Yichang Yangtze River Crossing Project Muddy siltstone, sand pebble structure West-East Gas Pipeline Jiujiang Yangtze River Shield Project 800m silty mudstone, mud Silty sandstone, 1800m silty Changji gas pipeline Songhuajiang shield project 350m strong weathered granite, 530m fault fracture zone Note: The effective operating time of directional drilling is specified to drill from the pilot hole The time taken for the pipeline to be pulled back, and the effective working time of pipe jacking and shielding means that the time from jacking to penetration is extensive to drilling and pipe jacking. In addition to not being suitable for crossing large geological caves and weak formations with low bearing capacity, it can Traverse various complex geology.
The shield is smoother than the jack pipe when passing through the fracture zone and fault. When encountering the lone rock, you can first grouting and consolidate the soil layer, and then enter the front cabin to manually use the pneumatic spear to break the rock or use the shield machine to directly break the rock Su Yong. Construction Technology of Horizontal Directional Drilling Crossing of Yangchang River on Tieqin Line.
Petroleum engineering construction, continued in 2009. Directional construction guide for trenchless pipelines. Beijing: Student of the Petroleum Industry Publishing Management Committee. The influence and treatment of big drift stone in shield type selection. Construction Mechanization, 2008 (4): Han Xuanjiang. Construction principle and application of large underground pipe jacking. Beijing: China Construction Industry Press, 2008: 15-16. (: 201 Bu 12-09; Editor: Sun Ling) 2 Choice of Trenchless Crossing Method: Zhang Baoqiang, engineer, born in 1980, graduated from PetroChina in 2006 The university (Beijing) majored in mechanical design and theory. Now it is mainly engaged in trenchless technology and equipment. As mentioned above, when comparing and selecting trenchless crossing methods, the research work should be carried out from the ground.
Quality, crossing length, pipeline protection and maintenance, construction efficiency, economy and administration
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