scholarly journals Study on Low Flow Rate Operating Characteristics of Hot Waxy Crude Oil Pipelines Based on an Unsteady-State Calculation Method

2015 ◽  
Vol 6 (0) ◽  
pp. 620848-620848 ◽  
Author(s):  
P. Yu ◽  
J. Zhang ◽  
B. Yu ◽  
Y. Wang ◽  
G. Yu
Keyword(s):  
Crude Oil ◽  
Flow Rate ◽  
Calculation Method ◽  
Low Flow ◽  
Unsteady State ◽  
Operating Characteristics ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
State Calculation ◽  
Oil Pipelines

scholarly journals Study on Optimizing Operation of Preheating Commissioning for Waxy Crude Oil Pipelines

2014 ◽  
Vol 6 ◽  
pp. 894256
Author(s):  
Jian Zhang ◽  
Yi Wang ◽  
Xinran Wang ◽  
Handu Dong ◽  
Jinping Huang ◽  
...  
Keyword(s):  
Crude Oil ◽  
Outlet Temperature ◽  
Fluid Temperature ◽  
Governing Equations ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Oil Pipeline ◽  
Single Station ◽  
Oil Pipelines ◽  
Volume Method

A mathematical model is established for the preheating commissioning process of waxy crude oil pipelines. The governing equations are solved by the finite volume method and the finite difference method. Accordingly, numerical computations are made for the Niger crude oil pipeline and the Daqing-Tieling 3rd pipeline. The computational results agree well with the field test data. On this basis, fluid temperature in the process of the preheating commissioning is studied for single station-to-station pipeline. By comparing different preheating modes, it is found that the effect of forward preheating is the best. Under different preheating commissioning conditions, the optimal combination of outlet temperature and flow rate is given.

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.

Wax Deposition Prediction and Control in Waxy Crude Oil Tieback Flowlines for South China Sea Deepwater Oil Development

2018 ◽  
Author(s):  
Xichong Yu ◽  
Chunsheng Wang ◽  
Qingping Li ◽  
Yan Li ◽  
Xiaosong Zhu ◽  
...  
Keyword(s):  
South China Sea ◽  
Crude Oil ◽  
Flow Rate ◽  
South China ◽  
Transient Flow ◽  
Wax Deposition ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
China Sea ◽  
Oil Development

Crude oils are generally very complex chemical systems consisting predominantly of hundreds to thousands of hydrocarbon compounds from simple low-molecular-weight paraffin to high-molecular-weight waxes. There are many factors effecting wax deposition such as the fluid composition, pressure and temperature and so on. Wax deposition is complex dynamic process related to transient heat and mass transfer, therefore it is very difficult to predict wax deposition velocity accumulation amounts on the wall in waxy crude oil tieback flowlines. There exist many waxy crude oil tieback flowlines for South China Sea deepwater oil development, which can cause many flow assurance problems. It is very important to carry out wax deposition prediction calculation and effective measures are adopted to solve flow assurance problems. In this study, based on certain waxy crude oil tieback flowlines for South China Sea deepwater oil development, OLGA software is used to simulate transient flow characteristics in waxy crude oil tieback flowlines such as wax precipitation rate, thickness of wax layer deposited at wall, pigging frequency and so on. OLGA software simulation results is coincident with field pigging operation results, finally obtaining a good simulation methods to predict transient flow characteristics in waxy crude oil tieback flowlines and giving good suggestions to determine pigging periods and frequency. The study results show two 10 inch non-insulation steel flowlines are recommended to develop deepwater waxy crude oil field and pigging periods should comprehensive consider thickness of wax layer deposited at wall and the increase of pressure caused by wax deposition. It is reasonable to 35 days pigging periods during 2 year after put into production, 60 days pigging periods after 2 years. The results show maximum liquid flow rate for a 10 inch flowline is 7000m3/d, and it is reasonable that one flowline is used to transport when flow rate is lower than 7000m3/d, and two flowlines are used to transport when flow rate is more than 7000m3/d. The pump pressure at FPSO is kept at 6000kPaA, and required maximum liquid flow rate of pigging at FPSO is 4200m3/d (175m3/h).

EXPERIMENTAL ANALYSIS OF THE FLOW START-UP OF GELLED WAXY CRUDE OIL IN A PIPELINE PREVIOUSLY SUBMITTED TO DIFFERENT PRESSURIZATIONS

2016 ◽  
Author(s):  
Gabriel Tanaka Nunes ◽  
Fernando Kroetz ◽  
Tainan Gabardo ◽  
Nezia de Rosso ◽  
Cezar Otaviano Ribeiro Negrao
Keyword(s):  
Crude Oil ◽  
Experimental Analysis ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Start Up

The role of shearing effect in evolution of the microscopic behavior of wax crystals

2021 ◽  
Author(s):  
Yuanhao Li ◽  
Jian Zhao ◽  
Hang Dong ◽  
Xiangrui Xi
Keyword(s):  
Crude Oil ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Dynamical Behaviors ◽  
Physical Phenomena ◽  
Wax Crystals

The microstructure and dynamical behaviors of wax crystals in waxy crude oil are the fundamental reasons for a series of physical phenomena in the process of transportation. In order to...

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