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Oil & Gas Storage and Transportation2021 11
ZHANG Jinjun1, LI Hongying1, HUANG Qian1, XIE Yiwei1, CHEN Chaohui1,2, MA Chenbo1,3, ZHANG Chaoyue1
Modification of crude oil is a basic method to improve the safety and economy of pipeline transportation. Definitely, high-voltage electric field treatment is a new approach to modify the crude oil based on its electrorheological effect. Herein, the progress of research on electric field treatment for modification of crude oil was summarized systematically, and the law of the electrorheological effect of crude oil was also concluded. The research results indicate that: applying an electric field (with an intensity of 0.2-5 kV/mm) to crude oil for several seconds can obtain the significant immediate modification effect. Specifically, the viscosity and yield stress can be reduced at a rate of 80% or higher, but the energy consumption is only 1% of that required for the same viscosity reduction rate by heating. After the removal of electric field, the viscosity and yield stress will recover gradually. The effect of viscosity reduction will disappear after about one day of placement. But the yield stress recovers slowly (at 90% of the reduction rate of yield stress two days later). The modification effect of electric field treatment is closely related to the composition of crude oil, and the presence of wax crystal, resin and asphaltene in the crude oil is essential for electric field treatment. In addition, the existing issues of the current research on electric field treatment technology were analyzed, and the development direction of the technology in the future was also proposed. (16 Figures, 50 References)
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YANG Fei1, WANG Bangwen2, LI Chuanxian1, LI Weiyu1
The marine oil spill accidents will not only result in the waste of energy, but also the unrecoverable destruction of the ecological environment. The superhydrophobic-superoleophilic 3D elastic porous materials are the most efficient oil adsorbents for the marine oil spill treatment, due to its low density, high porosity, strong elasticity, large oil adsorbing capacity and the convenient recovery of the materials and oil. Herein, based on the theoretical basis and the construction principles of the superhydrophobic-superoleophilic surface, the latest research progress was reviewed for three types of the superhydrophobic-superoleophilic 3D elastic porous materials respectively, i.e. the polymer-based, the carbon-based and the organism-based materials, in terms of the specific materials, the preparation method, and the application performance. Finally, the merits, defects and the faced challenges of the three types of the superhydrophobic-superoleophilic 3D elastic porous materials during their preparation and application were summarized, and the prospect was made for the development in future. (4 Figures, 67 References)
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TANG Yan, YU Haichao, FU Yingjie
On the 10th anniversary that the China-Russia Crude Oil Project (including the First and Second Mohe-Daqing Pipelines) was put into operation, its development history of the production and operation management in the 10 years was reviewed. Specifically, the pipeline overview was presented systematically, including the operation management mode of the First Mohe-Daqing Pipeline from scratch, the significance of capacity expansion and the key and difficult points thereof, the continuous intelligent improvement of the process system of the Second Mohe-Daqing Pipeline to be refined, and finally the comprehensive application of the regional management method. Additionally, the problems faced in the intellectualization of Mohe-Daqing Pipeline and the items to be perfected were summarized with reference to the strategic development goal of PipeChina. Finally, prospect was made from the macro perspective, namely, the enterprise upgrading and the intelligent development vision of oil pipelines will be brought about by the construction of a large intelligent interconnected pipeline network. (2 Tables, 21 References)
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LIU Xiaoben1, LIU Shen1, JI Beilei1, CHEN Pengchao2, ZHAO Xiaoli2, LI Rui2, ZHANG Hong1
Long-distance oil and gas pipelines passing through the areas with serious geological hazards are prone to bending deformation due to the external soil loads, which will threaten the safe operation of pipelines. The inline inspection technology based on the inertial measurement unit (IMU) is the main means to inspect the local deformation of pipelines at present. Herein, the characteristics of IMU data of the four typical locally-deformed pipeline sections, i.e. the buried pipeline elbows, the dented pipelines, the pipelines with bending deformation and the abnormal girth welds, were provided. Meanwhile, a IMU data pre-processing method based on wavelet denoising was put forward, a deep neural network model was established to identify the IMU data thermal map of the 4 types of typical locally-deformed pipeline sections, and a set of method was developed to identify the pipeline sections with bending deformation based on IMU data. By analyzing the 6-year IMU data of China-Russia Crude Oil Pipeline with the new method, totally 33 177 data of sample pipeline sections were formed, and an IMU bending strain database was set in China. The results of application example show that: the accuracy of the deep neural network model established based on the database to identify the pipeline sections with bending deformation is more than 90%, and the identification efficiency is up to 0.02 min/km. Hence, the method for identification of pipeline sections with bending deformation based on IMU data provides an effective technical means to identify the deformed pipeline sections with bending strain greater than 0.125% in the integrity assessment of pipelines. (9 Figures, 26 References)
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LIU Haipeng, GU Siyu, LIU Qingliang, ZHANG Jiankun, HAO Yu, WU Xiaocai, JIANG Yuanliang, WAN Peng
As an important part of pipeline integrity management, the alignment of the external and internal pipeline inspection data is to align the external inspection points to the internal inspection centerline, so as to fully mine the value of internal and external inspection data. Herein, from the perspective of the relationship between the surface marking points and the mileage piles of the pipelines, a relation model of internal inspection points and external inspection mileages was constructed using the machine learning algorithm based on the external and internal inspection data from the pipeline integrity management system of a long-distance pipeline company, and the mileage information of the internal inspection points in the external inspection was predicted to increase the mapping between the internal inspection points and the external inspection mileage, further realizing the data enhancement. In addition, the pipelines were segmented by the surface marking points and mileage piles, and the external inspection points were aligned to the internal inspection centerline with the linear stretching algorithm, so as to realize the alignment of the external and internal inspection data. The results show that the average absolute percent error is less than 0.10% and the determination coefficient is 99.99% for the internal inspection point based external inspection mileage prediction model established with the machine learning algorithm. Moreover, the model could capture the relationship between the internal inspection points and the external inspection mileages, so as to support the automatic alignment of the external and internal inspection data of the pipelines. (5 Figures, 1 Table, 21 References)
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ZHANG Xiyue, HU Jinqiu, ZHANG Laibin, DONG Shaohua, XU Kangkai
The textual generalization of accident risk factors is an important step to establish the knowledge graph of accident risk factors of the oil & gas storage and transportation enterprises. In order to solve the problem of semantic representation limitations and word segmentation errors for the textual generalization of risk factors accumulated in the production process of oil & gas storage and transportation enterprises by existing event text generalization methods, a textual generalization method of accident risk factors based on the Char-Word feature based AGNES (CW-AGNES) was put forward according to the complicated and changeable text expression of safety management. Definitely, the character feature and binary word feature vectors of the oil & gas storage and transportation enterprises were obtained by Word2vec method. The text of accident risk factors is vectorized according to the pre-trained word vector model. Then, the char-word features of the text are added with the agglomerative nesting method, and the error caused by word segmentation can be reduced on the basis of retaining the semantic information of the words, so as to realize the generalization of the risk factor text. Specifically, the CW-AGNES method was applied to the actual safety management texts of the oil & gas storage and transportation enterprises. Meanwhile, comparison was made with other generalization methods. The results show that: The CW-AGNES method has a better generalization effect with 2.44% –5.74% improvement in quantitative evaluation indicators such as AMI, ARI, V-Measure and FMI. Therefore, the proposed method could provide support for the construction of accident risk knowledge graph in the field of oil & gas storage and transportation. (3 Figures, 3 Tables, 20 References)
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FU Guangming1, LI Mingliang1, CHEN Jinghao2, PENG Yudan1, SUN Baojiang1, SHI Chen1
Compared with the traditional single-layer pipelines, the sandwich pipelines have a more complex structural configuration, and the problem of non-uniform filling thickness in the sandwich layer may occur easily in the manufacturing process, which could result in the decentraction of the inner and outer pipes, adversely affecting the external pressure bearing capacity of the pipelines. Therefore, a numerical model for the collapse strength of the eccentric sandwich pipelines under the external pressure was established with the finite element software ABAQUS, and the model was also verified with the experimental results of the existing literatures. In addition, the parametric modeling of the eccentric sandwich pipelines was realized with the Python script program, and the influence of the eccentricity with different initial ovality, inner pipe diameter to thickness ratio, material strength and interlayer bonding conditions on the compressive strength of the sandwich pipelines was studied. The results show that, with the increase of eccentricity, the collapse strength of the sandwich pipes decreases significantly. As the initial ovality increases, the collapse strength of the sandwich pipes decreases obviously. In the research condition, when the eccentricity is greater than 4 mm, the change of the diameter to thickness ratio of the inner pipe, the pipe material strength and the interlayer bonding conditions have more obvious effects on the collapse strength of the sandwich pipelines with the increase of eccentricity. The research results could provide reference for the engineering application of sandwich pipelines. (12 Figures, 2 Tables, 20 References)
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ZHANG Tieyao, SHUAI Jian, ZHANG Yinhui, REN Wei
To accurately obtain the true constitutive relationship of each material area in the girth welds of high-strength pipeline steel. Definitely, two kinds of notched round bar specimens were obtained by setting notches on the base metal and in the weld area of X80 steel respectively, and the tensile tests were carried out on the specimens, with the real-time images of specimen notches captured by the high-speed cameras during the tensile process. Then, based on the change law of gray value at the notch edge, an automatic measurement method, i.e. the minimum diameter tracing method, was proposed to measure the minimum sectional diameter of the notch area in real time. In addition, the true constitutive relationship between the base metal and the weld material can be obtained based on the minimum diameter tracing method and the modifier formula, and by fitting the curve obtained with the power law hardening model, the constitutive relationship parameters of corresponding materials can be gained. Finally, the test results were verified with the finite element method. The results show that both of the test method and the results are reliable and effective. The studied test method and the process are of great practical significance for obtaining the constitutive relationship between the base metal and the weld area and realizing the accurate test of the mechanical performance of the pipeline girth welds. (11 Figures, 5 Tables, 20 References)
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WANG Wenyue, WU Ying, YOU Xiao, CHEN Lang
The areas along the mountainous gas pipelines are complicated in geographic and geomorphic conditions, and thus greatly affected by earthquakes. Therefore, the safety and reliability assessment methods of mountainous gas pipelines under the influence of earthquakes were analyzed, which is of important strategic significance to ensure the safety of natural gas supply. From the prospective of the seismic risk and pipeline vulnerability factors, the method of calculating the weight of the index system under group decision-making with the improved Borda method was put forward. Meanwhile, the calculation methods of multi-index comprehensive measurement mentioned in the attribute recognition theory were divided into the types with “or” and “and” logics. Then, the calculation method of multi-index comprehensive measurement with “and” logics was proposed, and the assessment system for the seismic vulnerability of mountainous gas pipelines was established. In addition, the assessment system was applied to a mountainous gas pipeline in western Sichuan, and by introducing the attribute recognition theory, the attribute recognition was performed with the basic data combined with the expert opinions. In this way, the vulnerability level of the pipeline section was obtained. Generally, the results could provide reference for the prediction of the vulnerable pipeline sections in earthquakes and the development of the appropriate measures. (1 Figure, 8 Tables, 21 References)
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LIANG Fachun1,2, ZHAO Jingwen1, MENG Jia1, LI Qigui1, LI Naiming2
Liquid holdup is one of the most important parameters of gas-liquid two-phase flow. Affected by the image noise, the traditional liquid holdup measurement method based on image processing is difficult to accurately extract the gas-liquid interface, resulting in the great error of the liquid holdup measurement. Hence, a network model based on Deeplab V3+ was established with the semantic segmentation algorithm of deep learning, which was also trained by the image data set obtained from the slug flow pattern acquisition experiment, and then the interface of the gas and liquid flow area in the slug flow was identified and extracted to realize the measurement of the liquid holdup of the gas-liquid two-phase slug flow. The results show that the semantic segmentation model can extract the images of the gas-liquid two-phase flow online, and accurately divide the gas zone, liquid zone and background zone. In addition, the liquid holdup obtained by the top interface extraction is relatively high, while that obtained by the bottom interface extraction is relatively low, but the liquid holdup obtained by the average liquid film thickness is the closest to the true value measured by WMS (Wire-mesh Sensors) grid imaging sensors, with the maximum error less than 10%. The research results provide a new way for real-time monitoring of liquid holdup. (12 Figures, 18 References)
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GE Hua1, LI Kaihong1, WANG Leichao1, CHEN Sha1, XU Qiang1, ZHANG Bojun2, LI Zili2
Water accumulation in the low-lying areas of undulate pipelines will seriously threaten the operation of pipelines. Herein, the optimal pigging scheme for the initial pigging stage of the large undulate pipelines in mountainous areas was studied by test, and the calculation method for the volume of residual water in the low-lying area was proposed. The straight plate pig should be adopted in the initial pigging stage. Definitely, the optimum speed range of the straight plate pig should be 3.6-7.2 km/h, and the interference should be 4%-5%. Specifically, the water leakage of pigs was analyzed by changing the characteristics of pipelines, and thus the influence rules of different slope length, gradient, weld and elbows on water leakage were obtained. On this basis, the calculation method for the residual water volume and the average water film thickness on the pipeline wall in the low-lying areas was put forward through theoretical analysis. The research results could to provide reference and support for the subsequent deep pigging and drying operations. (14 Figures, 22 References)
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WANG Sen1, ZHU Liyun1, WANG Zhenbo1, HAN Xiao2
The connection pipes between the elbows of π-shaped pipelines can affect the movement of particles and the fluids, thereby greatly influencing the erosion of the elbows. Hence, the erosion of the gas-solid two-phase flow to the pipelines was simulated numerically with the Fluent software, and the erosion distribution and the changing law of erosion rate in the elbows of π-shaped pipelines under different connection pipe length were analyzed. The results show that the fourth elbow of the π-shaped pipeline was severely impacted by pitting corrosion, up to 5-10 times of other elbows. In addition, the variation of the length of the connection pipes would cause the change of the movement track of the solid particles, thus affecting the erosion distribution and the erosion rate of each elbow in the π-shaped pipelines. Definitely, with the increase of the length of the connection pipe, the erosion rate of the first three elbows changed little, but that of the fourth elbow decreased observably. When the length of the connection pipe increased to more than four times of the pipe diameter, the erosion rate of the fourth elbow decreased to 1/4-1/3 of that with the elbow connected directly, and the severity of pitting corrosion was reduced significantly. Generally, the research results herein could provide the theoretical guidance to the design, and maintenance of the π-shaped pipelines. (10 Figures, 3 Tables, 20 References)
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CUI Zhaoxue1, TIAN Lei2, DUAN Pengfei3, LI Luling3, LI Yuxing1, LIU Cuiwei1
The mixing of hydrogen will increase the leakage and explosion risk of natural gas pipelines. However, the pressure drop rate threshold of existing block valve in natural gas pipeline cannot meet the safety requirements of hydrogenblended natural gas pipeline transportation. Thereby, the pressure drop rate of the pipeline block valves under the leakage and distribution conditions was simulated and calculated by the SPS software, then a method for setting of the pipeline threshold was developed so that the changing rules of the pressure drop rate of the block valves and its appropriate threshold were gained by simulation under six influencing factors, and further the formulas for the pressure drop rate thresholds of the block valves were formed by fitting for pure gas and 10% hydrogen bending ratio natural gas pipelines respectively. The results show that: after the pipeline leaks, the upstream and downstream pressure drop rates increase with the increasing of the hydrogen blending ratio. The threshold of pressure drop rate increases with the hydrogen blended. The leakage position, pressure and length of the pipelines have great effect on the pressure drop rate threshold, but the flow, the pipeline diameter and the diameter of the leakage holes have little effect on the pressure drop rate threshold. Moreover, the calculated results of the threshold fitting formula are in good agreement with the simulation results. So, the research results could provide theoretical guidance for improving the intrinsic safety of the hydrogen-blend natural gas pipeline. (7 Figures, 1 Table, 24 References)
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YIN Yuanbo1, WANG Yazhen2, LIU Cuiwei1, LI Yuxing1
The leakage volume of natural gas is an important factor affecting the consequences of pipeline leakage and explosion. Restricted by the ratio of methane and air concentration, not all of the leakage gas will explode. Therefore, a calculation model for the explosive peak overpressure of premixed methane-air gas was established under unconstraint conditions. The relationship between the volume of premixed methane-air gas and the peak overpressure was simulated and analyzed with the Fluent software, and the calculation model was verified. Moreover, the law between the effective explosive volume of methane and the peak overpressure was obtained, and a method for calculating the effective volume was proposed. The results show that the propagation time of the explosion peak overpressure obtained by the numerical simulation model is consistent with the experimental results, and the attenuation law of the explosion peak overpressure is consistent with that as indicated by the existing research. Additionally, the effective volume of methane involved in the explosion is about 0.11 to 0.12 times the actual volume of the premixed gas, and the precision is high in the case the actual premixed gas volume is large. Hence, the results can provide a theoretical basis for the simulation and prediction of natural gas explosion, the consequence evaluation and the configuration of protection resources. (6 Figures, 6 Tables, 23 References)
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LI Xigui, TENG Lin, LI Weidong, HUANG Xin
In the process of hydrogen storage and transportation, if the high-pressure hydrogen in the storage tanks is released suddenly into the downstream pipelines, spontaneous ignition may occur, which can result in jet fire or explosion accidents. The obstacles such as the valves and welding slags inside the pipelines may affect the process and mechanism of spontaneous ignition of the leaked hydrogen. Therefore, a Computational Fluid Dynamics (CFD) model for the spontaneous ignition as a result of the high-pressure hydrogen leakage was developed and its reliability was validated by the experimental data. Subsequently, simulation analysis was performed for the spontaneous ignition process resulted from the high-pressure hydrogen leakage under the effect of obstacles at different locations in the pipelines. The results show that, the presence of obstacles has a significant influence on the shock wave propagation process in the pipelines, the variation of shock waves shows sensitivity to the obstacles, and the presence of obstacles in the pipelines will promote the flame propagation. In addition, the presence of obstacles increases the possibility of hydrogen spontaneous ignition in the pipelines, and the reflected shock waves generated by the obstacles will significantly change the spontaneous ignition mechanism of hydrogen. Generally, the research results could provide useful references for the design and safe operation of hydrogen pipelines. (9 Figures, 39 References)
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ZHANG Guoqiang1, LI Gang2, HAN Litao3
The Beijing-Shijiazhuang-Handan Gas Pipeline is characterized by large transportation capacity, multiple gas sources, large fluctuations in gas consumption, and frequent changes in operating parameters such as internal pressure, flow, and flow direction in the pipeline, which cause the major problems in pig operation speed control during pigging operations. In order to accurately control the operating speed of the pig, an online simulation model of Beijing–Shijiazhuang–Handan Gas Pipeline was established with PSIGanesi software. With the pig tracking function of the model, the location of pig in the pipeline, the average speed of the pig, the residual pigging distance and the remained pigging time can be calculated in real time, so as to provide the latest operation status of the pipeline network for the temporary adjustment of scheme for pigging operation. Herein, pigging operation with a cup pig, a straight plate pig and a brush pig in the pipeline section between Shijiazhuang Station and Xingtai Station was simulated in real time with the pig tracking function of PSIGanesi online simulation model. On this basis, the actual pigging time on site and real-time tracking time of the simulation model was compared, thereby the causes resulting in the deviations were analyzed and a correction method was developed. The research results could provide reference for the pipeline management departments to accurately locate the pig and control its operating speed. (5 Figures, 2 Tables, 21 References)
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About Journal
Administrator: China National Petroleum Corporation
Sponsor: PetroChina Pipeline Company
Editor and Publisher: Oil & Gas Storage and Transportation Journal Agency
Address: Oil & Gas Storage and Transportation Journal Agency, No.51, Jinguang Rd., Langfang City, Hebei Province, 065000, P.R. China
Post code: 065000
Tel: +86(316)2176173
Publication No: ISSN 1000-8241,CN 13-1093/TE
Periodicity: Monthly
Book Size: 16-mo
Establishment Year: 1977