A Method to Determine the Safe Time for High Waxy Crude Pipeline With Uncertainty

2012 ◽  
Author(s):  
Bo Xu ◽  
Qing Miao ◽  
Hao Lan ◽  
Feng Yan ◽  
Donglei Liu
Keyword(s):  
Crude Oil ◽  
High Viscosity ◽  
Gel Point ◽  
Pipeline Transportation ◽  
Safety Risk ◽  
Related Data ◽  
Natural Temperature ◽  
Operation Parameters ◽  
Operation Pressure ◽  
Uncertainty Of Parameters

More than 80% crude oils produced in China has a high content of wax. Pipeline transportation for such high waxy Chinese crude has a serious safety risk due to its characteristics of high gel point (up to 30 degree) and high viscosity below the wax appearance temperature. In the case of pipeline shutdown the crude cools down. After a certain amount of time, depending on the crude oil properties, the crude oil temperature plot file, the hydraulic data as well as the pipeline construction and environmental related data, the required pressure to restart the pipeline might exceed the maximum allowable operation pressure (MAOP) which makes the restart of operation become very difficult or even impossible. To mitigate the safety risk in case of the pipeline shutdown or to avoid congeal accident, determining the safe time after which the pipeline is still able to restart is necessary. However, the complexity of the presented problem lies in the uncertainty of the operation parameters and the environmental related data, such as the uncertainly of the flow rate and natural temperature. A method is developed to predict the safe time based on the uncertainty of parameters. In the method, the field data is firstly collected, then processed and analyzed to obtain the static rules of these data. By doing so, the complexity of uncertainty is successfully handled. The method is then applied to two pipelines, the results show that the safety of the pipeline is ensured and the energy consumption is also significantly reduced.

Heavy crude oil viscosity reduction and rheology for pipeline transportation

Fuel ◽  
2010 ◽  
Vol 89 (5) ◽  
pp. 1095-1100 ◽  
Author(s):  
Shadi W. Hasan ◽  
Mamdouh T. Ghannam ◽  
Nabil Esmail
Keyword(s):  
Crude Oil ◽  
Viscosity Reduction ◽  
Heavy Crude Oil ◽  
Pipeline Transportation ◽  
Oil Viscosity ◽  
Heavy Crude

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.

Effect of non-aqueous phase liquid on biodegradation of PAHs in spilled oil on tidal flat

2003 ◽  
Vol 47 (7-8) ◽  
pp. 243-250 ◽  
Author(s):  
T. Kose ◽  
A. Miyagishi ◽  
T. Mukai ◽  
K. Takimoto ◽  
M. Okada
Keyword(s):  
Crude Oil ◽  
Tidal Flat ◽  
High Viscosity ◽  
Fuel Oil ◽  
Dissolution Rates ◽  
Decrease Rate ◽  
Oil Biodegradation ◽  
Polycyclic Aromatic ◽  
Phase Liquid ◽  
Spilled Oil

Biodegradation rates of polycyclic aromatic hydrocarbons (PAHs) in spilled oil stranded on tidal flats were studied using model reactors to clarify the effects of NAPL on the biodegradation of PAHs in stranded oil on tidal flat with special emphasis on the relationship between dissolution rates of PAHs into water and viscosity of NAPL. Biodegradation of PAHs in NAPL was limited by the dissolution rates of PAHs into water. Biodegradation rate of chrysene was smaller than that for acenaphthene and phenanthrene due to the smaller dissolution rates. Dissolution rates of PAHs in fuel oil C were smaller those in crude oil due to high viscosity of fuel oil C. Therefore, biodegradation rates of PAHs in fuel oil C were smaller than those in crude oil. Biodegradation rates of PAHs in NAPL with slow decrease rate like fuel oil C were slower than those in NAPL with rapid decrease like crude oil. The smaller decrease rate of fuel oil C than crude oil was due to higher viscosity of fuel oil C. Therefore, not only the dissolution rate of PAHs but also the decrease rates of NAPL were important factors for the biodegradation of PAHs.

A Test for the Wettability of Carbonate Rocks

1970 ◽  
Vol 10 (01) ◽  
pp. 3-4 ◽  
Author(s):  
E.M. Duyvis ◽  
L.J.M. Smits
Keyword(s):  
Crude Oil ◽  
Carbonate Rock ◽  
Cold Water ◽  
Extraction Procedure ◽  
Soxhlet Extraction ◽  
High Viscosity ◽  
Spontaneous Imbibition ◽  
Rock Surface ◽  
Test Plate ◽  
Water Saturated

Direct imbibition experiments to test carbonate-rock wettability are occasionally prevented by high viscosity of the oil or rigid films between oil and water. The oil must then be removed from the rock before the imbibition test. A new extraction procedure was tested on limestones born Middle East reservoirs. Samples were taken from rubber-sleeve cores under nitrogen in a polythene glove bag to avoid formation of surface-active compounds through oxidation of crude oil. Conventional Soxhlet extraction of crude oil made water-wet carbonate rock oil-wet. Obviously the hot, dry solvent removes the water before the oil is completely extracted; the oil then contacts the rock surface, making it oil-wet. The extraction procedure was therefore modified so that cold and water-saturated chloroform reached the sample. To remove the oil effectively, the material was crushed and then stirred vigorously during extraction. Fig. 1 shows the extraction apparatus. The chloroform in the extraction thimble was kept saturated with water by the initial addition of some water to the boiling vessel. The vapor from this vessel is then richer in water than cold, water-saturated chloroform. The alundum thimble was made oil-wet (by dimethyl dichlorosilane allowing the solvent to pass through. Blank tests with water-wet and oil-wet samples showed a 1-week test to be appropriate for the extraction. The samples were dried and the wettability was determined by imbibition. A small amount of the sample was placed as a ridge in a hollow of a test plate and was wetted with toluene. By placing plate and was wetted with toluene. By placing water and toluene on either side of the ridge, we could determine whether water displaces toluene from the sample. This can be detected easily because sample material wetted with water is much lighter than that wetted with toluene. If water was indeed imbibed the sample was water-wet. Those samples in which water was not imbibed were tested as follows:the material was mixed with watera edge was again formed in a hollow; andwater and oil were placed on either side to determine whether or not toluene displaced water. So far, we have never observed this spontaneous imbibition. We therefore mixed the fluids and the sample and observed whether the grains were now wetted by toluene (darkening of the grain surface). If so, the sample was called oil-wet. A sample showing no imbibition in either case was neutral. The reliability of the procedure was verified by subjecting limestone core samples to both dry Soxhlet extraction and our wet extraction. The parts of samples from the dry extraction were parts of samples from the dry extraction were oil-wet, and those from the wet extraction were water-wet. Thus, either the samples were originally water-wet and became oil-wet by dry extraction, or they were originally oil-wet and became water-wet through wet extraction. The oil-wet samples could not be made water-wet by subsequent prolonged wet extraction. Thus the original samples must have been water-wet. Wet extraction does change an oil-wet condition to neutral, but never to water-wet. Therefore, a sample found to be water-wet was water-wet before extraction, and a sample found to be neutral was either oil-wet or neutral before extraction. P. 3

Pipeline Transportation of Heavy/Viscous Crude Oil as Water Continuous Emulsion in

1998 ◽  
Author(s):  
Kuldip Sharma ◽  
V.K. Saxena ◽  
Avinish Kumar ◽  
H.C. Ghildiyal ◽  
A. Anuradha ◽  
...  
Keyword(s):  
Crude Oil ◽  
Pipeline Transportation

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.

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