Investigation of the reasons for decreased efficiency of depressant additives during the pumping of paraffinic oils

Author(s):  
Alexander Y. Lyapin ◽  
◽  
Vladimir O. Nekuchaev ◽  
Sergei K. Ovchinnikov ◽  
Mikhail M. Mikheev ◽  
...  

The purpose of the research is to find out the reasons for the decrease in the effectiveness of the depressor additive DPN-1 as oil flows through the pipeline. The objects of the research are a mixture of paraffinic oils entering the Usa – Ukhta oil pipeline, either treated or untreated with DPN-1, as well as its mixture with highly-refined oil pumped from the Chikshino crude oil delivery and acceptance point. To achieve this goal, the rheological properties of oil were monitored at the main US oil pumping station, Chikshino and Ukhta-1 oil pumping stations; laboratory studies on the rheological properties attributed to simulated mixtures, compiled taking into account the volumes of oil delivered by various oil producers; and monitoring of the rheological properties of point samples of oils as they flow through the pipeline. The serial experiments resulted in establishing that the key factor in reduced efficiency of the DPN-1 additive used in the paraffinic oil mixture is the high pour point oil pumped from the Chikshino crude oil delivery and acceptance point (the share of which is 10 % of the total pumping volume).

Author(s):  
Hesham A. M. Abdou

The aged crude oil pipeline; 16″ × 166 km since November 1984, extends from Meleiha field at western desert to El-Hamra terminal at coast of the Mediterranean sea. Its original capacity was 100,000 BOPD using two pumping stations; one at Meleiha and the other is a boosting station, 83 km far from Meleiha. Planned pumped flow rate increased to 177,000 BOPD at the time that Maximum Allowable Working Pressure (MAWP) reduced from 1440 psi to 950 psi. This paper shows managing procedures led to pumping higher flow rate without exceeding MAWP, where two solutions to accommodate such increase in production were applied; firstly by looping the existing pipeline with a (16″ × 56 km), secondly by using a Drag Reducing Agent (DRA), so that could reduce hydraulic friction losses and Total Dynamic Pressure (TDP) in the system and could pumped more with reduced initial pumping pressure at Meleiha. So, the intermediate station was temporarily abandoned. Mathematical models are designed to simulate pumping operation through the whole system, where TDP is predicted for the three pipeline cases: 1- normal case without both looping & DRA. 2- case without DRA & with looping. 3- case with both looping & DRA. Laws of hydraulics are applied with the deduced formula represents performance of DRA in which percentage of drop in pressure losses is modeled as a function of DRA dose in ppm. Close agreement is remarked between values of the deduced theoretical values and actual values obtained for TDP, confirming validity of such mathematical models.


Author(s):  
T. T. Bekibayev ◽  
◽  
U. K. Zhapbasbayev ◽  
G. I. Ramazanova ◽  
A. D. Minghat ◽  
...  

The paper is devoted to the simulating of non-stationary processes of shutdown and restart on the example of a section of the Zhetybai-Uzen “hot” oil pipeline. A mathematical model of thermal-hydraulic calculation is given taking into account the rheological properties of the pumping oil. The special module of the SmartTran software developed by the work’s authors carried out the calculations. In the calculations, the decrease in time of oil temperature in the pipeline during cooling and the increase in oil pressure, temperature, velocity after the restart are determined. In addition, the calculations determine the power of pumping units, heating furnaces and the power consumption, which are necessary for restart of the pipeline after the shutdown. Simulation the processes of the pipeline cooling and restart after a shutdown makes it possible choosing the optimum parameters of pumping units at pumping stations and the time of safe shutdown of the oil pipeline.


2021 ◽  
Vol 18 (1) ◽  
pp. 145-162
Author(s):  
B Butchibabu ◽  
Prosanta Kumar Khan ◽  
P C Jha

Abstract This study aims for the protection of a crude-oil pipeline, buried at a shallow depth, against a probable environmental hazard and pilferage. Both surface and borehole geophysical techniques such as electrical resistivity tomography (ERT), ground penetrating radar (GPR), surface seismic refraction tomography (SRT), cross-hole seismic tomography (CST) and cross-hole seismic profiling (CSP) were used to map the vulnerable zones. Data were acquired using ERT, GPR and SRT along the pipeline for a length of 750 m, and across the pipeline for a length of 4096 m (over 16 profiles of ERT and SRT with a separation of 50 m) for high-resolution imaging of the near-surface features. Borehole techniques, based on six CSP and three CST, were carried out at potentially vulnerable locations up to a depth of 30 m to complement the surface mapping with high-resolution imaging of deeper features. The ERT results revealed the presence of voids or cavities below the pipeline. A major weak zone was identified at the central part of the study area extending significantly deep into the subsurface. CSP and CST results also confirmed the presence of weak zones below the pipeline. The integrated geophysical investigations helped to detect the old workings and a deformation zone in the overburden. These features near the pipeline produced instability leading to deformation in the overburden, and led to subsidence in close vicinity of the concerned area. The area for imminent subsidence, proposed based on the results of the present comprehensive geophysical investigations, was found critical for the pipeline.


2021 ◽  
Vol 1927 (1) ◽  
pp. 012021
Author(s):  
Junjiang Liu ◽  
Liang Feng ◽  
Dake Yang ◽  
Xianghui Li

2021 ◽  
Vol 205 ◽  
pp. 108881
Author(s):  
Xuedong Gao ◽  
Qiyu Huang ◽  
Xun Zhang ◽  
Yu Zhang ◽  
Xiangrui Zhu ◽  
...  

Author(s):  
Yuanyuan Chen ◽  
Jing Gong ◽  
Xiaoping Li ◽  
Nan Zhang ◽  
Shaojun He ◽  
...  

Pipeline commissioning, which is a key link from engineering construction to production operation, is aim to fill an empty pipe by injecting water or oil to push air out of it. For a large-slope crude oil pipeline with great elevation differences, air is fairly easy to entrap at downward inclined parts. The entrapped air, which is also called air pocket, will cause considerable damage on pumps and pipes. The presence of it may also bring difficulties in tracking the location of the liquid head or the interface between oil and water. It is the accumulated air that needed to be exhausted in time during commissioning. This paper focuses on the simulation of liquid-gas replacement in commissioning process that only liquid flow rate exists while gas stays stagnant in the pipe and is demanded to be replaced by liquid. Few previous researches have been found yet in this area. Consequently, the flow in a V-section pipeline consisted of a downhill segment and a subsequent uphill one is used here for studying both the formation and exhaustion behaviors of the intake air. The existing two-fluid model and simplified non-pressure wave model for gas-liquid stratified flow are applied to performance the gas formation and accumulation. The exhausting process is deemed to be a period in which the elongated bubble (Taylor bubble) is fragmented into dispersed small bubbles. A mathematical model to account for gas entrainment into liquid slug is proposed, implemented and incorporated in a computational procedure. By taking into account the comprehensive effects of liquid flow rate, fluid properties, surface tension, and inclination angle, the characteristics of the air section such as the length, pressure and mass can be calculated accurately. The model was found to show satisfactory predictions when tested in a pipeline. The simulation studies can provide theoretical support and guidance for field engineering application, which are meanwhile capable of helping detect changes in parameters of gas section. Thus corresponding control measures can be adopted timely and appropriately in commissioning process.


2013 ◽  
Vol 734-737 ◽  
pp. 2659-2663
Author(s):  
Yun Bin Ma ◽  
Dong Jie Tan ◽  
Hong Yuan Jing ◽  
Quan Xue ◽  
Cheng Zhi Zhang

The crude oil pipeline from MoHe to DaQing (hereafter called Mo-Da pipeline) is part of China-Russia oil pipeline. Mo-Da pipeline is the first pipeline that through high latitude cold regions of China. The pipeline is in so complicated geography environment that many kinds of permafrost hazard are easily to happen including frost heave, thaw settlement, slope instabilities, and collapse and so on. The pipeline and the permafrost act and react upon one another. On one hand, soil frost heave and thaw settlement can produce extra stresses on pipe walls, which may result in centralized stresses and plastic deformations under certain conditions, even causes pipeline faults. On the other hand, buried pipeline will disturb ambient environment and then degrade the permafrost soil and finally impact safety of the pipeline. This paper mainly introduces the permafrost hazards of Mo-Da pipeline and demonstrates some methods for monitoring the influence of permafrost.


Author(s):  
Берик Картанбаевич Саяхов ◽  
Александр Геннадьевич Дидух ◽  
Гульнара Амангельдиевна Габсаттарова ◽  
Марат Давлетович Насибулин ◽  
Жасулан Канатович Наурузбеков

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.


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