With the development and increasing application of the intelligent technologies such as big data, Internet of Things, cloud computing and artificial intelligence, the management in pipeline industry is transferring from the traditional way towards the digital and intelligent manner. Under the target of “full digital handover, full intelligent operation and full life cycle management”, a new mode with the artificial intelligent technologies deeply combined with the pipeline industry was established by PipeChina West East Gas Pipeline Company based on the management and technology innovation by focusing on the intelligent pipeline network, so that the industrial internet, machine learning, intelligent control and other technologies were introduced based on the existing pipeline operation system, the core technologies including intelligent inspection of stations, intelligent control of distribution and intelligent verification of flowmeters were developed, and the development of the intelligent operation technology for natural gas pipelines and stations was further promoted. Besides, the core technologies such as the gas leakage detection, intelligent operation and maintenance management of stations and the intelligent monitoring of the compressor units and flowmeters were innovated by greatly developing the comprehensive intelligent perception technology for the key equipment of natural gas pipeline. Further, the key technologies such as risk intelligent identification, fiber optic safety warning and intelligent corrosion protection of pipeline were upgraded by building the technical system of intelligent risk management and control. On this basis, the operation efficiency of intelligent pipeline has been further improved by PipeChina West East Gas Pipeline Company and a prototype of intelligent pipeline network with the characteristics of “full perception, comprehensive prediction, integrated management and control, and adaptive optimization” was built, providing a valuable reference for the development of intelligent oil and gas pipelines in China. ( 2 Tables, 23 References)

With the main features of comprehensive perception, automatic prediction, self-adaptation, self-feedback and selflearning, the intelligent pipeline network has been developed rapidly in recent years. However, the focus of intelligent network varies at home and abroad. The focus is to upgrade the traditional technologies with modern models in foreign countries while the planning and overall design of intelligent system is focused in China. The construction of intelligent pipeline network in China is still in its early stages, it lacks of systematicness, planning and scientificity in construction of digital twins, sensing technology, accurate detection and evaluation, decision-making support, modeling, information sharing and deep mining of big data, and the basic model and intelligent decision-making are insufficient. The development and application of intelligent pipeline network in multiple pipelines of PipeChina were illustrated, with the coverage of such links as design, construction and operation realized. As for the existing problems, the following solutions were put forward: intelligent patrol, artificial intelligence of intelligent pipeline network, real-time video monitoring and intelligent recognition, intelligent emergency preparedness, construction of intelligent platform based on multi-source data, integrated intelligent monitoring and early warning of disasters, big data fusion, modeling and decision-making support of pipeline integrity, etc. It is recommended to further develop the full-life-cycle data standard of pipeline, build full-life-cycle database of pipeline, organize the platform design of intelligent pipeline network, including the asset management and control, operation control and decision-making support in the full-life-cycle of pipeline, and finally form an intelligent integrated management platform based on multi-source data fusion with the technologies of Internet of Things, cloud platform and blockchain, etc. (21 References)

Construction of high voltage direct current (HVDC) transmission system and long-distance oil and gas pipelines has greatly optimized the allocation of energy resources in China. However, attention should be paid to the strong direct current interference caused by the discharging of the HVDC grounding electrode to the buried pipelines. In order to further strengthen the management and control of the relevant risks, the development history of HVDC transmission grid in China was summarized, the typical characteristics of the influence of HVDC grounding electrode by discharging on the buried pipelines were analyzed, and the development direction of risk management and control was identified according to the actual conditions. The results indicate that the influence of HVDC lines and grounding electrodes on the nearby longdistance oil and gas pipelines in the same route has the characteristics of random time, complex interference mechanism, great interference intensity and difficulty in mitigation, and it is one of the prominent safety risks pipelines face to presently. During the commissioning or fault running of the HVDC transmission grid, discharging of single grounding electrode will accelerate the corrosion of buried pipelines. In the future, the level of inspection, research and governance should be enhanced by strengthening the communication, coordination and joint testing, studying the corrosion mechanism and rules in depth and taking the comprehensive governance measures, so as to guarantee the safety and stability of the national energy corridors in all rounds. (32 References)

Wax deposition is a severe flow assurance challenge for waxy crude oil transportation. Generally, mechanical pipeline pigging is used to remove the wax deposits on pipeline wall. However, the field pigging operation relies greatly on the experience due to the poor understanding of wax removal mechanism, and pig plugging and wax blockage occur frequently. Here, the fundamental issues in wax removal by pigging of crude oil pipeline were summarized, the research progress from the perspectives of wax removal mechanism, wax removal efficiency and wax breaking force was clarified, and it was also pointed out that the mechanical strength of wax deposits, rheological properties and flowing characteristics of the oil-wax slurry in front of the pig, as well as the critical condition for wax plug formation, would be key issues and main directions of future research in this field. (3 Figures, 41 References)

The era of big data has brought about great changes in industry. In order to improve the efficiency, security and automation level of industrial production, it is necessary to find out the hidden rules in the massive data by fully mining and utilizing the big data of industry, so as to improve the level of information management in industry, further providing reliable technical support for intelligent monitoring, operation and maintenance. Herein, the application solution and effect of data mining in load forecasting, safety warning, scheduling optimization and performance monitoring of natural gas pipeline network under the context of big data were analyzed with specific cases. Based on that, the development direction of data mining and other relevant technologies was discussed from the perspectives of multi-data fusion, establishment of integrated information platform and full-life-cycle management. Moreover, the application of data mining in natural gas pipeline network was prospected. (8 Figures, 22 References)

In terms of the requirements for simulating multi-phase transportation system, different topological structures and transportation technology of gathering and transportation pipeline networks in the intelligent construction of digital oilfields, a general data structure of pipeline network, capable of expressing the complex connection relationship, was designed on the base of the graph theory method and the target of pipeline network. A universal non-linear equation set of pipeline network was established by coupling the hydro-thermal mathematical model of a flow unit and the equilibrium relationship of nodes, and a solution method with high robustness was proposed. Computing software was developed for the independent use in the scenarios of design, operation and optimization of the gathering and transportation technologies of an oilfield or the integrated application in an integrated management system. By comparing the calculation results of commercial softwares, the adaptability and accuracy of the software were verified, and meanwhile, its application prospects were discussed from the aspect of engineering practice. (22 Figures, 1 Table, 32 References)

To solve the actual problems of accurate control of flow and quality during the verification of natural gas, an intelligent metrological verification system applicable to the medium-high pressure gas under the condition of multiple sources was researched and developed, so that the communication barriers between industrial control and data processing system during the original verification process were broken, with the data of multiple systems fused and interconnected with the instructions and interacted in real time, realizing the full intelligent control of verification equipment. With the system, a quality control system platform for standard equipment was established, the variation trend and impact of the deviation of standard equipment were assessed in real time through risk prediction, the performance evaluation business of flow meters was expanded, the operation status of flow meters in the full life cycle was analyzed and evaluated by establishing a multi-dimensional mathematical analysis model, the whole-process remote operation of the operation station control system of the data center was realized by reconstructing the operation mode of verification, and the intelligent assembling and disassembling of instruments with explosion-proof AGV vehicles, explosion-proof mechanical arms, and a customized vision measurement system was explored. Moreover, the prospect was made to the intelligent metrological verificatio technology of natural gas in the 3 aspects of the online verification and calibration technology, the intelligent upgrading of metering technology, and the industrialized metrological platform. (5 Figures, 19 References)

With the continuous promotion of urbanization in China in recent years, the surrounding environment of some pipelines is changing constantly, and the scope of the high-consequence areas of the pipeline section is also changing. Accurately and efficiently mastering the data of environment change to update the information of the high-consequence areas is very important for the safety management of the pipeline companies. According to the characteristics of less change of natural features but frequent change of artificial features along the pipeline in short term, a method for detection of the change of the high-consequence areas based on the multi-source remote sensing image with high-resolution orthoimage and multispectral image was put forward. In this method, the change information of multi-source data is extracted with the LBP-HOG fusion feature and spectral gradient difference method based on the super-pixel segmentation. Experiments show that, the change of artificial features along the pipeline can be detected accurately with this method, so that the efficiency for management of high-consequence areas could be improved effectively. (9Figures, 1Table, 20References)

Oil pipelines are characterized with long mileage, high risk of transportation medium and complex hydrogeological conditions. Once oil leaking occurs in environmentally sensitive areas, serious environmental pollution may be caused. Taking a high consequence area of an environment as example, a conceptual model, a water flow model and a solute transport model were established on the base of Visual-Modflow software to simulate the migration and diffusion law of petroleum hydrocarbon in groundwater under the situation of oil pipeline leakage. The state of groundwater was early warned with the improved Nemero comprehensive pollution index method, and the early-warning level of different wells was determined according to the relationship between the change rate of water quality and the early-warning level. As indicated in the results, evaluation on early warning of the pollution risk of groundwater in case that leakage occurs to an oil pipeline, could effectively pre-warn the leakage of oil and predict the diffusion trend of the leaked oil of the pipeline. (4 Figures, 6 Tables, 20 References)

In guided-wave based pipeline non-destructive inspection, it is inevitable that guided waves will interact with multiple defects, which makes damage identification more challenging. In this study, a numerical simulation was conducted to investigate the interaction of longitudinal guided waves with double notches in pipes. Firstly, a three-dimensional finite element model was established to simulate guided wave propagating in a pipe with a single notch. Then the established model was validated by comparing with existing experiments results. Based on the validated model, the guided wave reflection characteristics of two equal-sized notches of various relative positions were discussed systematically. The results show that, the relative circumferential positions of the two notches have little influence on the overall reflection, and the reflection coefficient rarely varies with the circumferential distance. However, the overall reflection of the two notches at the same circumferential location mainly depends on their axial positions, and the reflection coefficient varies periodically with the axial distance of the two notches. Moreover, the reflection coefficients of multiple notches within some axial range follow superposition principle approximately, which is very helpful for group corrosion detection. (10 Figures, 3 Tables, 20 References)

Natural gas venting will have a significant impact on the gas sources and users, and great safety risks may exist in engineering practice. Therefore, gas venting is one of the important tasks in the maintenance and construction of the gas pipeline. Determining the key parameters of venting with scientific tools based on the actual conditions of gas pipelines and requirements of the related standards and codes is critical to ensure the safety and economy of venting. Definitely, the initial pressure of venting was determined, a feasible venting method was selected, the venting time was calculated and its impact on the environment was evaluated through in-depth analysis of the China Myanmar Natural Gas Pipeline. Additionally, the practice of venting the China Myanmar main pipeline was discussed to provide important practical basis and technical support for reasonably organizing the maintenance and construction of gas pipelines and improving the decision-making level of gas production scheduling. (10 Figures, 4 Tables, 20 References)

Coupling alignment of the motor-driven centrifugal compressor unit will affect the operation stability of the unit. Therefore, it is necessary to verify and correct the cold alignment data of the compressor manufacturer on site to ensure the accuracy of cold alignment, thus improving the quality of cold alignment of the unit. According to the structure and operation characteristics of centrifugal compressor unit, the differences of the unit in cold state and normal operation state were analyzed, the factors affecting the cold alignment were obtained, and the formula for calculating and correcting the cold alignment data was proposed. The effect of cold alignment was analyzed from the four aspects of material thermal expansion, rising height of shaft and deflection of alignment tool. In the calculation process of thermal expansion values, an obvious linear relationship was found, which simplified the numerical calculation of thermal expansion. The rising height of the rotor shaft center was obtained from the condition monitoring tool, the jacking height of rotor in the process of cold alignment was corrected, and the corrected cold alignment data was obtained finally, which is of reference significance to guide the cold alignment of compressor. (9 Figures, 1 Table, 23 References)

With the deep development of domestic and international oil and gas fields, due to the complicated and harsh medium conditions, high density polyethylene (HDPE) lining technology becomes one of the important measures to control the corrosion leakage of the surface gathering & transportation system and water injection system in oil and gas fields and to extend the service life of pipelines. With the lining principle of isodiametric compression for HDPE liner and in accordance with the domestic and foreign standards and specifications, the material performance requirements of HDPE liner, the applicable conditions of HDPE lining technology, the fitness of liner with the base pipe and the design principles for vents were proposed from the 3 aspects of design, construction and economy. Moreover, the wall thickness of HDPE liner was determined based on the minimum thickness for installation & storage, the stability and the collapse resistance of liner, and through comparative analysis on the joint type of different HDPE liner technologies, it was proposed to consider the flange joint preferably. In addition, the construction & installation process of HDPE liner and the lining form of hot induction bend were introduced, the key points and requirements of construction quality control were summarized, and the economic efficiency of different material selection schemes for pipeline in oil and gas field was compared, so as to advance the application of HDPE liner technology in oil and gas fields and to solve the problem of pipeline corrosion leakage in the oil and gas fields. (2 Figures, 3 Tables, 20 References)

In order to reduce the frequency of false shutoff of the block valve in a long-distance gas pipeline and improve the reliability of the leakage detection system in a valve chamber, the leakage simulation model of a long-distance gas pipeline was established with SPS simulation software by referring to the theory of gas fluid mechanics based on the analysis on causes of a large number of false shutoff events occurred in valve chambers. With this simulation model, the influence rules of the conditions including the leakage location and operating pressure of a pipeline on the process of pressure drop during the leakage of a long-distance gas pipeline was studied, and on that basis, the process data of the possible maximum pressure drop during the leakage of a pipeline was calculated. Then, a judgment algorithm for false shutoff of block valves in a natural gas pipeline was designed, and a control procedure was developed for shutoff of block valves in a leaked pipeline.The simulation data and experimental results show that with the method, the false shutoff signal and the real leakage signal can be distinguished according to the characteristics of pressure change, and the rate of false shutoff of the system could be reduced. (5 Figures, 28 References)

In actual operation, the pigging period of wet-gas pipeline should be determined by some methods to guarantee the efficiency of pipeline transportation. In order to study the adaptability of common determination methods for pigging cycle of wet-gas pipeline in China, the disadvantages of minimum gas transmission efficiency method, maximum allowable pressure drop method and maximum liquid inventory method were analyzed. Additionally, the variation rules of pipeline transportation efficiency and liquid inventory after pigging were emphatically studied based on two actual pipelines. The results show that the key factor to determine the pigging cycle is the volume of liquid slug as a result of pigging rather than the liquid inventory in pipeline when the maximum liquid inventory method is adopted, and it is limited to determine the pigging cycle by static liquid inventory. In the case of large throughput of pipeline, the minimum gas transmission efficiency method and the maximum allowable liquid inventory method are also limited for the pigging cycle obtained is infinite. For actual pipelines, the pigging cycle obtained by the minimum gas transmission efficiency method or the maximum liquid inventory method is too short, which cannot provide guidance for determination of field pigging cycle. (6 Figures, 1 Table, 28 References)

For diesel transported by long-distance pipeline, its quality decreases with the increase of transportation distance. Here, the factors affecting the diesel transport quality of the Western Products Pipeline were studied through batch tracking and sampling test. The results show that the average flash point attenuation of 0# and －35# diesel at the terminal station are 5.75 ℃ and 3 ℃, respectively. Thus, the recommended minimum flash point of 0# and －35# diesel filled into the pipeline should be 66 ℃ and 48 ℃, respectively. In the case of batch transportation, the quality attenuation of diesel is relatively serious due to the great difference of the quality between adjacent oil products, and the quality of diesel attenuates more seriously with the increasing shutdown time of pipeline. Hence, the shutdown of pipeline should be minimized. The impurities in the pipeline can also result in the quality decrease of diesel transported. So, regular pipeline pigging is conductive to improving the quality of pipeline diesel. Additionally, change of pipeline flow, which is greater than the critical flow, has little influence on the quality of diesel transported. Conclusively, the research results could provide theoretical reference for economic and efficient operation of long-distance products pipelines. (4 Figures, 4 Tables, 23 References)

The difference of vapor cloud density and the variation of atmospheric turbulence caused by ambient temperature are the main factors influencing the leakage and diffusion of LNG.Hence,it is very necessary to study the influence of the variation of ambient temperature on the diffusion rules of LNG.With the component transport model and the Realizable k-ε turbulence model in Fluent software,a numerical model of vapor diffusion caused by the surface leakage of LNG was established to explore the influence of ambient temperature on the volume fraction distribution of methane, vapor cloud density and atmospheric turbulence intensity in the process of LNG leakage and diffusion.The results show that under the low ambient temperature,the volume fraction lines of methane in the LNG vapor cloud is in the shape of “sawtooth”,resulting in the increase of the horizontal diffusion range of the Low Flammability Limit (LFL) and 1/2 LFL of the methane, while under the high ambient temperature,the maximum range of diffusion of methane at LFL is 115m farther than that under the low ambient temperature which leads to the increase of the diffusion range of methane at 1/2LFL in the horizontal downwind direction. In addition, the increment of the turbulence intensity increases with the rise of the temperature in the area where the volume fraction of methane is greater than 1/2LFL,while it decreases with the rise of temperature in the area where the volume fraction is less than 1/2 LFL. In the range of 100-200m around the source of leakage, the increment of the turbulence intensity resulted by “temperature inversion” can be up to 0.79times.The research results could provide references for prediction on leakage region,safety storage and transportation and emergency rescue of LNG.(13 Figures,38 References)