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

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.

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.

scholarly journals Wax inhibitor performance comparison for waxy crude oil from Fang oilfield

2021 ◽  
Vol 294 ◽  
pp. 06005
Author(s):  
Kreangkrai Maneeintr ◽  
Tanapol Ruengnam ◽  
Thodsaporn Taweeaphiradeemanee ◽  
Treetasase Tuntitanakij
Keyword(s):  
Crude Oil ◽  
Pour Point ◽  
High Efficiency ◽  
Performance Comparison ◽  
Wax Deposition ◽  
Cold Finger ◽  
Waxy Crude Oil ◽  
Waxy Oil ◽  
Point Reduction ◽  
Higher Temperature

In petroleum chemistry, waxy oil from paraffins can cause operating problems for oil production. The chemical method is used to remove by using chemicals or additives to prevent the wax problem. In this study, the performance of wax inhibitor are evaluated by the measurement of pour-point reduction and wax deposition of crude oil from Mae Soon area, Fang oilfield. Wax deposition is determined by cold finger technique. Wax inhibitors, hexane, Poly(maleic anhydride-alt-1-octadecene) (PMAO) and monoethanolamine (MEA) are mixed in oil sample at various concentrations. From the experiment, it is presented that hexane is used to reduce pour-point temperature up to 19.55 % and to reduce wax deposit up to 92.56 %. Moreover, MEA and PMAO have less effect on pour-point reduction. However, they have high efficiency to prevent wax deposition. PMAO provide the better wax deposition performance than MEA. The amount of wax deposit is lower at the same conditions. The percentage of wax deposit is from 39.19 % to 83.02 % for MEA and from 58.54 % to 88.51 % for PMAO. Furthermore, from the results, the preferred concentration of hexane can be at 10 % and PMAO can be 7500 ppm at low temperature or 5000 ppm for higher temperature. The results of this research can be applied to the practical way for wax deposition prevention operation in Mae Soon area in Fang oilfield to reduce the wax problem in the future.

Study of the causes for wax deposition under the operating conditions of main oil pipelines

2020 ◽  
Vol 10 (6) ◽  
pp. 610-619
Author(s):  
Rustam Z. Sunagatullin ◽  
◽  
Rinat M. Karimov ◽  
Radmir R. Tashbulatov ◽  
Boris N. Mastobaev ◽  
...  
Keyword(s):  
Phase Diagrams ◽  
Total Content ◽  
Operating Conditions ◽  
Wax Deposition ◽  
Oil Saturation ◽  
Oil Pipelines ◽  
Thermobaric Conditions ◽  
Wall Zone ◽  
Significant Factors ◽  
Commercial Oil

The results of investigations of the main causes and the most significant factors of intensification of paraffin deposition in main oil pipelines are presented. A comprehensive analysis of the composition and properties of commercial oils and their sediments was carried out, according to which phase diagrams of equilibrium of oil dispersed systems were obtained using the example of commercial oils from Bashkir fields. Based on the phase diagrams, a curve of wax oil saturation was constructed, the analysis of which confirms that the existing thermobaric conditions during the operation of main oil pipelines do not allow transporting oil without the risk of waxing. It was noted a special influence of the value of the temperature gradient in the near-wall zone and the imbalance of the ratio of high-molecular oil components in commercial batches formed in the process of joint pumping on the intensity of waxing of sections of oil pipelines complicated by deposits, which was confirmed by statistical data on the frequency of pigging. The regularities obtained in this way are proposed to be used as an express method for predicting complications associated with intensive waxing of main oil pipelines. In order to quickly assess the risks of waxing of sections of main oil pipelines, an indicator is introduced that characterizes the ratio of the content of solid paraffins to the total content of resins and asphaltenes of oil, called the criterion of instability of a commercial oil batch.

Using clusterization principles for the selection of repair sections of main oil pipelines based on diagnostic data

2011 ◽  
Vol 8 (1) ◽  
pp. 201-210
Author(s):  
R.M. Bogdanov
Keyword(s):  
Cluster Analysis ◽  
Defect Density ◽  
Density Variation ◽  
Distance Functions ◽  
Oil Pipeline ◽  
Oil Pipelines ◽  
Classification Of Images ◽  
Main Oil Pipeline ◽  
Selection Of

The problem of determining the repair sections of the main oil pipeline is solved, basing on the classification of images using distance functions and the clustering principle, The criteria characterizing the cluster are determined by certain given values, based on a comparison with which the defect is assigned to a given cluster, procedures for the redistribution of defects in cluster zones are provided, and the cluster zones parameters are being changed. Calculations are demonstrating the range of defect density variation depending on pipeline sections and the universal capabilities of linear objects configuration with arbitrary density, provided by cluster analysis.

scholarly journals Role of Shearing Dispersion and Stripping in Wax Deposition in Crude Oil Pipelines

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4325
Author(s):  
Zhihua Wang ◽  
Yunfei Xu ◽  
Yi Zhao ◽  
Zhimin Li ◽  
Yang Liu ◽  
...  
Keyword(s):  
Crude Oil ◽  
Flow Rate ◽  
Critical Flow ◽  
Wax Deposition ◽  
Dominant Effect ◽  
Critical Flow Rate ◽  
Oil Pipelines ◽  
Oil Flow ◽  
Shearing Mechanism

Wax deposition during crude oil transmission can cause a series of negative effects and lead to problems associated with pipeline safety. A considerable number of previous works have investigated the wax deposition mechanism, inhibition technology, and remediation methods. However, studies on the shearing mechanism of wax deposition have focused largely on the characterization of this phenomena. The role of the shearing mechanism on wax deposition has not been completely clarified. This mechanism can be divided into the shearing dispersion effect caused by radial migration of wax particles and the shearing stripping effect caused by hydrodynamic scouring. From the perspective of energy analysis, a novel wax deposition model was proposed that considered the flow parameters of waxy crude oil in pipelines instead of its rheological parameters. Considering the two effects of shearing dispersion and shearing stripping coexist, with either one of them being the dominant mechanism, a shearing dispersion flux model and a shearing stripping model were established. Furthermore, a quantitative method to distinguish between the roles of shearing dispersion and shearing stripping in wax deposition was developed. The results indicated that the shearing mechanism can contribute an average of approximately 10% and a maximum of nearly 30% to the wax deposition process. With an increase in the oil flow rate, the effect of the shearing mechanism on wax deposition is enhanced, and its contribution was demonstrated to be negative; shear stripping was observed to be the dominant mechanism. A critical flow rate was observed when the dominant effect changes. When the oil flow rate is lower than the critical flow rate, the shearing dispersion effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. When the oil flow rate is higher than the critical flow rate, the shearing stripping effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. This understanding can be used to design operational parameters of the actual crude oil pipelines and address the potential flow assurance problems. The results of this study are of great significance for understanding the wax deposition theory of crude oil and accelerating the development of petroleum industry pipelines.

Study of the physical, chemical and rheological properties of oil mixtures transported through the Uzen - Atyrau - Samara pipeline

2021 ◽  
pp. 420-427
Author(s):  
Берик Картанбаевич Саяхов ◽  
Александр Геннадьевич Дидух ◽  
Гульнара Амангельдиевна Габсаттарова ◽  
Марат Давлетович Насибулин ◽  
Жасулан Канатович Наурузбеков
Keyword(s):  
Rheological Properties ◽  
Pour Point ◽  
Heating Temperature ◽  
High Viscosity ◽  
Rheological Parameters ◽  
Polarization Microscopy ◽  
Oil Pipeline ◽  
Physical Chemical ◽  
Wide Range ◽  
Oil Mixtures

На начальных участках магистрального нефтепровода Узень - Атырау - Самара формируются партии низкозастывающих бузачинских и высокозастывающих мангышлакских нефтей. По маршруту транспортировки осуществляются дополнительные подкачки нефтей с различными физико-химическими и реологическими характеристиками, что может оказывать существенное влияние на свойства перекачиваемых нефтесмесей. Цель настоящей работы - исследование физико-химических и реологических свойств бузачинской и мангышлакской нефтесмесей на маршруте поставки Узень - Атырау, а также диапазона и причин изменений характеристик бузачинской нефти (основной в компонентном составе нефтесмесей, перекачиваемых по нефтепроводу Узень - Атырау - Самара). По результатам исследований установлено, что свойства мангышлакской нефтесмеси изменяются в незначительных пределах. Для бузачинской нефтесмеси свойственна нестабильность реологических параметров, которые могут изменяться в широком диапазоне в результате путевой подкачки на различных участках нефтепровода. Колебания реологических параметров наиболее показательных проб партий бузачинской нефтесмеси рекомендуется учитывать для решения задач повышения текучести высоковязких нефтей и оптимизации технологических режимов работы трубопроводов, по которым осуществляется перекачка таких нефтей. Методами газохроматографического анализа молекулярно-массового распределения тугоплавких парафинов и поляризационной микроскопии определена температура нагрева бузачинской и мангышлакской нефтесмесей, оптимальная для ввода депрессорной присадки. At the initial sections of the Uzen - Atyrau - Samara main oil pipeline, batches of low pour point Buzachinsky and high pour point Mangyshlak oils are formed. Additional pumping of oils with different physical, chemical and rheological characteristics is carried out along the transportation route, which can have a significant effect on the properties of the pumped oil mixtures. The purpose of this study is to examine the physical, chemical and rheological properties of Buzachi and Mangyshlak oil mixtures on the Uzen - Atyrau supply route, as well as the range and causes of changes in the characteristics of Buzachinsky oil (the main oil mixture in the blend composition pumped through the Uzen - Atyrau - Samara pipeline). According to the research results, it was found that the properties of the Mangyshlak oil mixture vary within insignificant limits. The Buzachinsky oil mixture is characterized by instability of rheological parameters, which can vary in a wide range as a result of route pumping at different pipeline sections. Fluctuations of the rheological parameters of the most indicative samples of batches of the Buzachinsky oil mixture are recommended to be taken into account in order to increase the fluidity of high-viscosity oils and optimize the process modes of operation of pipelines through which such oils are pumped. Using the methods of gas chromatographic analysis of the molecular weight distribution of high-melting-point paraffins, as well as polarization microscopy, the optimal heating temperature for the introduction of a pour point depressant into the Buzachinsky and Mangyshlak oil mixtures has been determined.

Modified equations for hydraulic calculation of thermally insulated oil pipelines for the case of a power-law fluid

2021 ◽  
pp. 388-395
Author(s):  
Марат Замирович Ямилев ◽  
Азат Маратович Масагутов ◽  
Александр Константинович Николаев ◽  
Владимир Викторович Пшенин ◽  
Наталья Алексеевна Зарипова ◽  
...  
Keyword(s):  
Power Law ◽  
Analytical Calculation ◽  
High Viscosity ◽  
Hydraulic Calculation ◽  
Flow Index ◽  
Pipeline System ◽  
Power Law Fluid ◽  
Simplified Approach ◽  
Oil Pipeline ◽  
Oil Pipelines

Теплогидравлический расчет неизотермических трубопроводов является наиболее важным гидравлическим расчетом в рамках решения задач обеспечения надежности и безопасности работы нефтепроводной системы. Для практических расчетов применяются формулы Дарси - Вейсбаха и Лейбензона. При этом в ряде случаев (короткие теплоизолированные участки, поверхностный обогрев нефтепроводов) можно использовать упрощенный подход к расчету, пренебрегая изменением температуры или учитывая температурные поправки. В настоящее время формулы для аналитического расчета движения высоковязких нефтей в форме уравнения Лейбензона получены только для ньютоновской и вязкопластичной жидкостей. Для степенной жидкости соответствующие зависимости отсутствуют, расчет ведется с использованием формулы Дарси - Вейсбаха. Целью настоящей статьи является представление формулы Дарси - Вейсбаха для изотермических течений степенной жидкости в форме уравнения Лейбензона. Данное представление позволит упростить процедуру проведения аналитических выкладок. В результате получены модифицированные уравнения Лейбензона для определения потери напора на участке нефтепровода в диапазоне индекса течения от 0,5 до 1,25. В указанном диапазоне относительное отклонение от результатов расчетов с использованием классических формул Метцнера - Рида и Ирвина не превышает 2 %. The thermal-hydraulic calculation of non-isothermal pipelines is the most important hydraulic calculation in the framework of solving the problems of ensuring the reliability and safety of the oil pipeline system. For practical calculations, the Darcy - Weisbach and Leibenson formulas are used. Moreover, in a number of cases (short heat-insulated sections, surface heating of oil pipelines), a simplified approach to the calculation can be used, neglecting temperature changes or taking into account temperature corrections. At present, formulas for the analytical calculation of the motion of high-viscosity oils in the form of the Leibenson equation have been obtained only for Newtonian and viscoplastic fluids. For a power-law fluid, there are no corresponding dependences; the calculation is carried out using the Darcy - Weisbach formula. The purpose of this article is to present the Darcy - Weisbach formula for isothermal flows of a power-law fluid in the Leibenzon form, which will simplify the procedure for performing analytical calculations. The modified Leibenzon equations are obtained to determine the head loss in the oil pipeline section in the range of the flow index from 0.5 to 1.25. In the specified range, the relative deviation from the results of calculations using the classical Metzner - Reed and Irwin formulas does not exceed 2 %.

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