scholarly journals Safety Study on Wax Deposition in Crude Oil Pipeline

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1572
Author(s):  
Bin Yao ◽  
Deyin Zhao ◽  
Zhi Zhang ◽  
Cheng Huang
Keyword(s):  
Crude Oil ◽  
Cloud Point ◽  
Freezing Point ◽  
Development Trend ◽  
Wax Deposition ◽  
Scanning Calorimetry ◽  
Long Distance ◽  
Wax Precipitation ◽  
Oil Pipeline ◽  
Precipitation Characteristics

The Shunbei crude oil pipeline is prepared to use the unheated transportation process to transport waxy crudes. However, the wax formation in the pipeline is unknown. In order to predict the wax deposition of the pipeline, the physical property experiment of Shunbei crude oil was carried out through field sampling. The density, freezing point, hydrocarbon composition, and viscosity–temperature characteristics of crude oil are obtained. The cloud point and wax precipitation characteristics of the crude oil were obtained using the differential scanning calorimetry (DSC) thermal analysis method. Then, the wax deposition rate of the pipeline was predicted by two methods: OLGA software and wax deposition kinetic model. Finally, the optimal pigging cycle of the pipeline was calculated on this basis. The results show that: Shunbei crude oil is a light crude oil with low wax content, a low freezing point, and a high cloud point. Comparing the OLGA simulation results with the calculation results of the Huang Qiyu model, the development trend of wax deposition along the pipeline was the same under different working conditions. The relative error of the maximum wax layer thickness was 6%, proving that it is feasible for OLGA to simulate wax deposition in long-distance crude oil pipelines. Affected by the wax precipitation characteristics of Shunbei crude oil, there was a peak of wax precipitation between the pipeline section where crude oil temperature was 9.31–13.31 °C and the recommended pigging cycle at the lowest throughput was 34 days in winter and 51 days in spring and autumn.

Oil Temperature Prediction of Long-Distance Hot-Crude-Oil Pipeline Based on GA-BP Optimization

2020 ◽  
Author(s):  
Tao Yu ◽  
Peng Dong ◽  
Yang Yu ◽  
Jinzhou Song ◽  
Jie Zhang
Keyword(s):  
Prediction Model ◽  
Crude Oil ◽  
Pour Point ◽  
Theoretical Formula ◽  
Production Data ◽  
Influence Coefficient ◽  
Long Distance ◽  
Temperature Prediction ◽  
Oil Pipeline ◽  
Actual Production

Abstract Due to the high pour point of the oil products transported in the long-distance high wax crude oil pipeline, in order to ensure the operation safety, it is necessary to adopt heating transmission technology, so as to ensure that the oil temperature along the pipeline is 3–5 °C higher than the pour point, that is to say, the oil temperature is the most important operation parameter of the long-distance hot oil pipeline, and the accurate prediction and control of the oil temperature is the premise of the pipeline safety optimization. Aiming at the problems of large prediction error and poor applicability of the previous theoretical formula, this paper studies the establishment of oil temperature prediction model by using data mining algorithms such as Back Propagation (BP) neural network, and improves the prediction efficiency and accuracy of the model by using Genetic Algorithm (GA) optimization. The correlation coefficient formula is used to calculate the influence coefficient of oil temperature, ground temperature, pipeline transportation and other parameters on the inlet oil temperature of the downstream station, so as to obtain the input parameters of the model. The actual production data training model is downloaded through SCADA system, and the prediction accuracy of the control model is ±0.5 °C. Compared with BP model and other theoretical formulas, the accuracy and efficiency of GA-BP oil temperature prediction model are greatly improved, and the adaptability is better. The GA-BP oil temperature prediction model trained according to the actual production data can be effectively applied to the future pipeline big data platform, which lays a theoretical foundation for the intelligent control of the pipeline.

scholarly journals Unavoidable Destroyed Exergy in Crude Oil Pipelines due to Wax Precipitation

Entropy ◽  
2019 ◽  
Vol 21 (1) ◽  
pp. 58
Author(s):  
Qinglin Cheng ◽  
JinWei Yang ◽  
Anbo Zheng ◽  
Lu Yang ◽  
Yifan Gan ◽  
...  
Keyword(s):  
Crude Oil ◽  
Design Parameters ◽  
Burial Depth ◽  
Outlet Temperature ◽  
Waxy Crude Oil ◽  
Wax Precipitation ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Oil Pipelines ◽  
Operation Parameters

Based on the technological requirements related to waxy crude oil pipeline transportation, both unavoidable and avoidable destroyed exergy are defined. Considering the changing characteristics of flow pattern and flow regime over the course of the oil transportation process, a method of dividing station oil pipelines into transportation intervals is suggested according to characteristic temperatures, such as the wax precipitation point and abnormal point. The critical transition temperature and the specific heat capacity of waxy crude oil are calculated, and an unavoidable destroyed exergy formula is derived. Then, taking the Daqing oil pipeline as an example, unavoidable destroyed exergy in various transportation intervals are calculated during the actual processes. Furthermore, the influential rules under various design and operation parameters are further analyzed. The maximum and minimum unavoidable destroyed exergy are 381.128 kJ/s and 30.259 kJ/s. When the design parameters are simulated, and the maximum unavoidable destroyed exergy is 625 kJ/s at the diameter about 250 mm. With the increase of insulation layer thickness, the unavoidable destroyed exergy decreases continuously, and the minimum unavoidable destroyed exergy is 22 kJ/s at 30 mm. And the burial depth has little effect on the unavoidable destroyed exergy. When the operation parameters are simulated, the destroyed exergy increases, but it is less affected by the outlet pressure. The increase amplitude of unavoidable destroyed exergy will not exceed 2% after the throughput rises to 80 m3/h. When the outlet temperature increases until 65 °C, the loss increase range will not exceed 4%. Thus, this study provides a theoretical basis for the safe and economical transportation of waxy crude oil.

Study of Wax Deposition Rate in Waxy Crude Oil Pipeline

2013 ◽  
Vol 401-403 ◽  
pp. 891-894 ◽  
Author(s):  
Qing Lin Cheng ◽  
Xu Xu Wang ◽  
Xian Li Li ◽  
Wei Sun ◽  
Ling De Meng
Keyword(s):  
Crude Oil ◽  
Deposition Rate ◽  
Normal Operation ◽  
Wax Deposition ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Oil Transportation ◽  
Different Seasons ◽  
Deposition Tendency

In waxy crude oil transportation process, wax crystals start to precipitate as the oil temperature drops to wax appearance point, and then form a network structure gradually which attaches to the wall. The problem of wax deposition seriously affects the normal operation of pipeline. Based on the wax deposition tendency coefficient method, combined with experimental data, the parameters related to wax deposition tendency coefficient is fitted, and the wax deposition rate equation of crude oil is determined finally. The variation law of wax deposition rate along the pipeline is analyzed, and the influence of different seasons and different throughput the on wax deposition rate is discussed subsequently.

Analysis of Hot Oil Pipeline Stress Influencing Factors

2014 ◽  
Vol 887-888 ◽  
pp. 899-902
Author(s):  
Xiao Nan Wu ◽  
Shi Juan Wu ◽  
Hong Fang Lu ◽  
Jie Wan ◽  
Jia Li Liu ◽  
...  
Keyword(s):  
Crude Oil ◽  
High Viscosity ◽  
Analysis Model ◽  
Long Distance ◽  
Oil Pipeline ◽  
Software Analysis ◽  
Key Points ◽  
Temperature And Pressure ◽  
Pressure Changes ◽  
The Impact

In order to reduce the viscosity of crude oil for transport, we often use the way of heating delivery for high pour point, high wax, and high viscosity oil. Crude oil at high temperature, through long-distance transmission, the temperature and pressure changes on the piping stress greater impact. In this paper, in order to explore the main factor of hot oil pipeline stress and the location of key points, we build the XX hot oil pipeline stress analysis model used CAESAR II software, analysis of the impact of changes in temperature and pressure on piping stress when hot oil pipeline running, draw hot oil pipeline stress distribution, clearly identifies the location of key points of stress concentration, and we have come to that temperature is a major factor in generating pipe stress.

Prediction of Wax Deposition in an Insulation Crude Oil Pipeline

2015 ◽  
Vol 33 (15-16) ◽  
pp. 1499-1507 ◽  
Author(s):  
Z. Hu ◽  
M. Wu ◽  
K. Hu ◽  
J. Liu
Keyword(s):  
Crude Oil ◽  
Wax Deposition ◽  
Oil Pipeline

The Model of Wax Precipitation and Experimental Validation

2012 ◽  
Vol 463-464 ◽  
pp. 1182-1185 ◽  
Author(s):  
Bing Qiang Zhang ◽  
Da Shuai Xue ◽  
Ji Cheng Yang
Keyword(s):  
Rheological Property ◽  
Pour Point ◽  
Wax Deposition ◽  
Wax Precipitation ◽  
Oil Pipeline ◽  
Waxy Oil ◽  
The Past ◽  
Oil Pipelines ◽  
Experimental Values ◽  
Pipeline Safety

A comprehensive review of literature concerning rheological property, and wax deposition during involving the pipeline safety problems is presented. The deposition and gelation of waxy oil pose great flow assurance risks, especially in submarine oil pipeline. Even though there have been a lot of studies and breakthroughs in understanding the wax precipitation and deposition in the past few years, there still continue to be some challenges that have remained unsolved. In order to well understand the rheological property of the crude oil, First of all, the issue need to be solved is study the wax precipitation property of the oil. In this paper, an accurate model of wax precipitation in laboratory condition undergoing a cooling process is established. And then we predicted the wax appearance temperature, pour point and the weight of the wax appearance about the oil sample. Here, the calculated results of model are much close to the experimental values, which shows that the model of wax precipitation developed is correct and reasonable. By accurate prediction the WAT, pour point, we can well understand the rheological property, which will help the operators make an impeccable flow restart plan for the planned or emergency production shut-down of waxy oil pipelines

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