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The technology related to oil and gas pipelines abroad has developed rapidly in recent years; many new technologies, processes, materials, and equipment are being used in the construction of new pipelines and the renovation of existing ones. This has effectively reduced project costs, improved construction quality, and ensured the smooth commissioning of newly built pipelines. Due to the long construction times for pipelines abroad and the serious safety risks associated with them, pipeline companies in those countries are actively pursuing technological innovations aimed at reducing energy consumption and ensuring safe operations. They conduct regular inspections and integrity assessments of existing pipelines, and use computer systems to optimize operational management. We keep track of the latest developments in pipeline technology abroad, with the aim of identifying gaps and clarifying directions, so as to provide references for future research initiatives in the field of oil and gas pipelines in our country. In 1928, the Soviet Union built a welded steel long-distance crude oil pipeline from Grozny to Tuapse, marking the beginning of the development of the modern pipeline industry. To date, after more than 70 years of development, the global pipeline industry, especially in industrially advanced regions such as Europe and the United States, has made significant progress in areas ranging from pipe manufacturing and design to construction, as well as in transportation processes, pipeline automation control, and operation management. Oil and gas pipelines are playing an increasingly important role in the world’s transportation sector. At the same time, various new processes, technologies, materials, equipment, and products related to pipeline transportation have emerged in large numbers. In particular, starting from the 1960s, the pipeline industry entered a period of rapid development, and oil and gas pipeline companies around the world placed great emphasis on the research and development of advanced technologies; many pipelines made extensive use of the latest research findings during their design and construction. The use of highly automated technologies not only ensures the safe and reliable operation of pipelines, but also reduces the need for operators, **lowers operating costs, and helps companies achieve better profit levels. This article summarizes the main development trends in the transportation technologies for crude oil, refined products, and natural gas pipelines abroad. I. Development trends in foreign crude oil pipeline transportation technology At present, for the long-distance transportation of high-viscosity and easy-to-solidify crude oil worldwide, heating and dilution are still the two main methods used. In light of the declining throughput of existing pipelines year by year and the increasing exploitation of heavy oil, research on various new technologies and combined processes aimed at improving pipeline operation safety and reducing energy consumption has become a focus. Studies on various processes such as physical field treatment (magnetic treatment, vibration-based viscosity reduction), water transportation (liquid ring, suspension, emulsification), device-based transportation (sliding box, membrane bag), gas injection for viscosity reduction (using saturated gas to increase throughput), mixed transportation, and sequential transportation have already reached the stage of industrial testing and short-distance trial operations in some cases. Overall, the transportation technologies for crude oil pipelines abroad are evolving toward diversification and innovation. For crude oil of a specific quality, a transportation process is effective only under specific conditions. In other words, different transportation processes are used for different types of crude oil and in different geographical environments. Although there are differences in the level of development of the pipeline industry across countries around the world, the criteria for evaluating the quality of a transportation process should be consistent, mainly including the following points: (1) Efficiency. It has a significant viscosity-reducing and drag-reducing effect, or it is effective for a certain type of viscous oil. (2) Adaptability. It has a wide range of applications and exhibits high adaptability to the properties of oil products, the distance between stations, the volume of transport, and the transportation environment. (3) Simplicity. The process equipment is simple, easy to use and maintain, features a high degree of automation, and facilitates centralized control and management. (4) Economical efficiency. Low energy consumption, low cost, and high efficiency. Advanced crude oil pipelines abroad generally employ closed-transmission systems, high-efficiency heating furnaces, and energy-saving oil transfer pumps ； Highly automated computer simulation systems are used to simulate pipeline operation and accident scenarios, carry out leak detection, and optimize pipeline scheduling and management ； Regular safety inspections and integrity assessments are carried out on existing pipelines. For example, the Transcontinental Pipeline System in the United States is one of the most advanced pipelines for transporting crude oil by heat in the world. With a total length of 2,715 km and a diameter of 760 mm, it relies on a computer-based monitoring and control system (SCSS). Operators at the control center can use computers to achieve automatic control over pipeline flow rates, pressures, as well as various equipment such as pumps, boilers, and valves. Simulation software enables functions such as leak detection, location determination, optimal equipment configuration, operational simulation, and training simulations. At present, long-distance crude oil pipelines in China, as well as in countries such as the United States, the Soviet Union, and Indonesia, widely employ heating-based transmission methods. In terms of these technical approaches, China is on par with foreign countries; however, there are still certain gaps in pipeline operation management and the effective utilization of key transmission equipment. 1. Current status of heating furnace application technology Heating furnaces are the main energy-consuming devices in oil pipelines for transporting hot crude oil. The Soviet Union primarily used direct-type heating furnaces, while the United States used both direct-type and indirect-type heating furnaces. Since the late 1980s, China has begun to use indirect heating furnaces on a large scale. Compared with foreign countries, their degree of automation is low; the corrosion resistance of key components such as heat exchangers and furnace tubes is poor, and the actual performance of the automatic control and regulation systems in these furnaces is insufficient. Waste heat recovery devices commonly suffer from corrosion, dust accumulation, and low heat transfer efficiency. In the future, efforts should be made from an energy-saving perspective to develop new technologies and equipment for improving combustion efficiency, particularly in the areas of new types of high-efficiency burners, waste heat recovery devices, and fuel additives. 2. Speed regulation and energy-saving technology for oil transfer pumps According to statistics, the operating efficiency of oil transfer pumps in China is 10% to 20% lower than that of advanced foreign systems. A considerable number of these pumps operate at partial load, with flow rates far below their rated values, while the operating pressures are much higher than the rated values. Valve throttling has been traditionally used; although it is effective in practical applications, it results in significant energy waste and represents an uneconomical operating method. Currently, large oil transfer pumps abroad generally use motor speed control, which can achieve a power savings rate of up to 40%, resulting in very significant energy-saving effects. In our country, the application scope of speed-regulating and energy-saving technologies for oil transfer pumps is relatively limited, and the following problems mainly exist: (1) The speed-regulating device should be selected based on the different operating patterns of the pump (referring to the range of flow rates and the duration of operation at each flow rate). The operating patterns of pumps can generally be divided into four types: high-flow variation type, low-flow variation type, full-flow variation type, and full-flow intermittent type. For high-flow variable applications, speed control methods such as thyristor cascading and hydraulic couplings are recommended ； Pumps with low-flow variable mode and full-flow intermittent mode generally use variable frequency speed control, but they should be equipped with a device for automatic switching between low speed and full speed ； For pumps with variable flow rates, variable frequency speed control is more suitable when operating at low flow rates for extended periods; whereas for long periods of operation at high flow rates, cascade speed control or less efficient speed control devices are used. (2) The capacity of the pump should be taken into account when selecting a speed control device. For large oil transfer pumps of 100 kW and above, energy savings are significant; therefore, high-efficiency speed control devices should be given priority when selecting such devices. For small-capacity pumps of 100kW or less, the initial investment in speed control devices should be kept as low as possible. (3) Pay attention to the speed control range of the motor. The speed adjustment range of the pump motor should not be too large; typically, the minimum speed is not less than 50% of the rated speed, and it generally lies between 70% and 100%. Because when the speed is below 40% to 50%, the pump’s efficiency drops significantly, which is uneconomical. Furthermore, from both technical and economic perspectives, attention should also be paid to the reliability and maintainability of the speed control device, as well as the impact of the power factor and higher harmonics on the power grid; an optimal solution should be selected through comprehensive analysis and comparison. 3. Automatic metering system for crude oil storage tanks Currently, there are mainly two methods for measuring crude oil in storage tanks: one is based on volume, and the other is based on mass. Most foreign oil companies use volume measurement methods. Their tank automatic metering systems consist of a measurement system and a computer monitoring system, among which the measurement of the average temperature of the oil in the tank is key to determining the accuracy of measurement. For oil-gas mixed transport pipelines, foreign countries are currently researching and developing multiphase flow mass flow meters. Such meters can simplify the process flow, allowing for direct measurement without the need for separation of oil, gas, and water; they eliminate the need for metering separators and metering manifolds, thereby reducing construction and maintenance costs. II. Finished Oil Pipeline Transportation Technology The United States leads the world in finished oil pipeline transportation, with its main pipelines accounting for over 50% of the total length of such pipelines worldwide; Canada, Western Europe, and the Soviet Union follow behind. Foreign refined oil pipelines are commercial pipelines that deliver products in multiple batches, across various varieties, and to different destinations, targeting consumption centers and end-users. They feature a high level of automation in operation, with automatic control over operational parameters, leak detection, monitoring of mixture concentrations, tracking of fluid interfaces, and oil separation. The main trends in their development include the following: (1) Refined oil pipelines are evolving towards larger diameters, higher flow rates, and the ability to handle multiple batches of products; in addition to transporting refined oil, they also carry other liquid hydrocarbon compounds. The transportation plans are highly comprehensive; for example, the Colonial Pipeline system in the United States, the world’s largest pipeline system for refined oil products, can transport three times as much volume after its dual-track version is completed. The two tracks allow for the sequential transportation of 118 different grades of refined oil products, with each sequential cycle taking only 5 days. (2) Widely adopt pipeline optimization operation management software systems to reasonably arrange the transfer times for different batches of oil products. The system can automatically generate scheduling plans in a very short time, conduct dynamic graphical analysis of the flow of oil within the pipelines, and remotely control the start and stop of pumps and valves to provide proactive protection against water hammer effects. (3) Currently, ultrasonic testing is the emerging trend for detecting the oil mixture interface in the sequential transportation of refined oil, with the United States holding a leading technological position in this area. III. Development of natural gas pipeline transportation technology Foreign countries began developing long-distance natural gas pipelines quite early on; as early as the 1950s, the Soviet Union started constructing such pipelines. By the 1980s, it had built 6 ultra-large central gas transmission systems with a total length of nearly 20,000 km and pipe diameters ranging from 1,220 to 1,420 mm – these are the largest pipeline projects in the world today. After more than half a century of development, foreign long-distance natural gas pipelines have made significant progress in terms of design, construction, operation and management, as well as in pipeline materials, prime movers, and storage and peak-shaving technologies. In particular, the construction technology for large-diameter, high-pressure main pipelines is at the forefront, offering many valuable experiences and mature techniques that can be utilized as references. Currently, the development of foreign gas pipeline technology features mainly the following aspects: (1) Increasing the pipe diameter. The diameter of main natural gas pipelines abroad is generally over 1000 mm; for example, the pipeline that carried gas from the Soviet Union to Europe had a diameter of 1420 mm, while the famous Azeri-Turkmen gas pipeline had a diameter of 1220 mm. Moreover, the construction technology for large-diameter pipelines abroad is highly advanced, whereas China is still somewhat lacking in this area. (2) Increase the gas transmission pressure. Currently, the gas pipeline pressures in Western Europe and North America are generally above 10 MPa; for example, the Ayy pipeline reaches a maximum outlet pressure of 21 MPa at its crossing points, while the Norwegian Statepipe pipeline operates at a pressure of 13.5 MPa. The newly built Alliance pipeline has a maximum allowable operating pressure of 12 MPa. (3) Widely adopt internal coating drag-reduction technology to improve transportation capacity. The use of internal coatings in foreign gas pipelines generally allows an increase in gas transmission capacity by 6% to 10%; at the same time, it also helps to reduce equipment wear and the frequency of pipe cleaning, thereby extending the pipeline’s service life. (4) To improve the toughness of pipes and increase their wall thickness, pipe manufacturing technology is developing rapidly. X70 grade pipes are commonly used in foreign gas pipelines, and X80 grade pipes have also been employed in pipeline construction. German company RuhrgasAG used X80-grade pipes for the first time on its pipeline running from Hessen to Werne (φ 1219mm). According to relevant literature, using X80 grade pipes can save 7% in construction costs compared to X65 grade pipes. Currently, gas pipelines in countries such as Canada and France use X80-grade pipes; in addition, steel pipe manufacturers in Japan and Europe are developing X100-grade pipes. (5) Advanced peak-shaving technology. To ensure a reliable, safe, and continuous supply of gas to users, developed countries use metal gas storage tanks and underground gas storage facilities for peak-demand gas supply. Currently, in the West, **seasonal peak shaving primarily relies on porous and salt cavern underground gas storage facilities, while short-term peak shaving such as daily and weekly adjustments is accomplished using gas storage at the ends of pipelines and in underground pipe networks. Natural gas storage tanks are mainly high-pressure spherical tanks, with the maximum geometric volume of such tanks abroad reaching 5.55 × 104 m3. (6) Increase the power of compression units, widely adopt regenerative cycle gas turbines, and use these gas turbines to provide power or generate electricity. Compressor units used in foreign long-distance gas transmission pipelines are generally of high power; for example, the average power of each compressor unit at Gazprom’s compressor stations in Russia is over 10 MW. The same is true in Europe and the United States. The MS300 regenerative cycle gas turbine produced by General Electric in the U.S. has a rated power of 10.5 MW, the LM2500 model has a power of 22 MW, and the MS5000 model has a power of 24 MW. The use of gas turbine regenerative cycles and combined cycle systems has achieved excellent energy-saving results. For example, in the famous Ayy pipeline project, the gas turbine units at the Messina compressor station were upgraded to use regenerative combined cycle systems, resulting in an increase in the overall thermal efficiency of each gas turbine from 36.5% to 47.5%. Abroad, new technologies such as mechanical dry sealing for compressors, magnetic bearings, and fault diagnosis are also widely used. These technologies not only extend the service life of bearings, eliminate the need for a lubrication system, and reduce the operating costs of compressors, but they also significantly improve the reliability and integrity of the entire unit. In addition to the above features, foreign natural gas pipelines have also made some new advances in metering technology, leak detection, and storage technology. 1. Calorific value measurement technology for natural gas Measurement plays an extremely important role in natural gas testing technologies. Accurate measurement not only helps to avoid various issues in the upstream, midstream, and downstream stages of natural gas trading, but also improves the efficiency of pipeline management. Foreign natural gas metering technology has gone through three development stages: volume metering, mass metering, and calorific value metering. After the 1980s, the use of calorific value metering technology became increasingly widespread in Western Europe and North America, and it has now become the direction of development for natural gas metering technology. The measurement of natural gas’s calorific value is a more scientific and fair method compared to volume- or mass-based measurement. Since the composition of natural gas remains relatively stable, pricing based on its calorific value allows higher-quality gas to be priced higher; this approach is widely used abroad as a basis for pricing. With China’s accession to the WTO, and in order to improve the level of energy management in the country and align it with international standards, China will also promote the use of calorific value measurement technology in the future. There are two methods for determining the calorific value of natural gas: direct measurement and indirect calculation. The traditional indirect calculation method involves first measuring the concentrations of various components in the natural gas, and then calculating the calorific value of the mixture. In recent years, direct measurement techniques for natural gas calorific value have developed rapidly, with significant improvements in terms of automation, continuity, and accuracy. 2. Infrared radiation detectors American natural gas utilities typically use flame ionization detection technology (FID) to detect leaks in main pipelines and urban distribution networks, and this technology is very effective. However, due to the slow speed of the inspection vehicle (usually only 3–7 m/h), the high labor intensity, and the high costs, these factors directly affect the quality of the inspection results. Currently, the Gas Research Institute (GRI) in the United States is conducting research on laser-based remote sensing leak detection technology, which utilizes the property of infrared spectroscopy (IR) to absorb methane in order to detect gas leaks. This remote sensing system consists of an infrared spectrum receiver and an on-vehicle detector, enabling rapid large-area scanning of the heat plumes resulting from gas leaks from a distance. Field tests have shown that the leak detection efficiency has increased by over 50% compared to previous methods, while costs have been significantly reduced. In addition, countries such as Canada, the United States, and Russia **also install infrared or laser remote sensing detectors on helicopters for gas leak detection**, which reduces inspection cycles and expands the detection range. 3. Research and application of natural gas pipeline drag reducers (DRA) Chevron Petroleum Technology Co. in the United States conducted field tests on a gas transmission pipeline in the Gulf of Mexico using natural gas drag reducers (DRA). The results show that the flow rate can be increased by 10% to 15%, while the maximum pressure can decrease by up to 20%. The main chemical component of this drag-reducing agent is polyamide. By using an injection system, the agent is injected into natural gas pipelines at regular intervals and in a certain concentration. It forms a smooth protective layer on the inner surface of the pipes; this layer significantly reduces transportation friction and also provides some anti-corrosion protection. The gas pipeline drag reducer developed by Chevron has a limited service life inside the pipes; after a certain period of time, the film will peel off on its own, and the drag-reduction efficiency will decrease as well. Field tests have shown that the effective lifespan of DRA can reach 400 hours. 4. Natural gas storage technology From a commercial perspective, foreign pipeline companies attach great importance to the research on technologies aimed at minimizing the amount of gas required to fill large-scale storage facilities. Currently, research is being conducted on using a low-volatility and inexpensive gas as a \"working gas\" to serve as a buffer cushion in gas storage caverns. Other gas storage technologies of interest include natural gas injection, extraction metering, improved monitoring and automation, as well as information on the temperature effects in salt cavern gas stores.