流花16-2油田海底管道原油蜡沉积规律模拟分析北大核心CSCD

流花16-2油田海底管道原油在深水不保温输送过程中,管壁结蜡对管道全线总传热系数的变化影响很大。本文通过室内环道蜡沉积实验建立流花16-2油田管道蜡沉积预测模型,模拟研究了不同沉积时间条件下管道沿线结蜡速率及结蜡厚度的变化,并引入单位时间管道全线总结蜡量概念对管道全线结蜡速率进行了描述。结果表明,在管壁结蜡层的保温作用下,管道沿线最大蜡层厚度位置处的总传热系数迅速降低导致后管段油流温度升高,管道沿线蜡沉积速率峰值向管段末端移动;随着沉积时间的增长,管道全线结蜡区域逐渐扩大,导致单位时间管道全线总结蜡量增大;根据管道沿线最大蜡层厚度2 mm或管道全线总结蜡量10 m^3的沉积时间,推荐流花16-2海底管道清管周期为3~5 d,以保障海底管道的安全运行。     

中洛原油管道结蜡规律

通过建立濮阳原油蜡沉积模型,预测不同运行工况下中洛管道沿线的结蜡厚度分布。同一运行条件下,沿着管道输送方向,管壁结蜡厚度逐渐增大,到达结蜡高峰区后逐渐减小;随着运行时间的延长,结蜡最严重处略向后方偏移。随着出站温度的降低,中洛管线内出现蜡沉积的管段逐渐增长;结蜡最严重处逐渐向出站处推移,且蜡层厚度基本相同。     

姬塬油田黄9井区油井清蜡与防蜡技术应用效果分析

采用理论分析和现场生产实践相结合的方法，分析油井结蜡的过程及影响结蜡的因素，通过一系列油井清蜡与防蜡措施的实施，稳定了油井的产量，延长了油井结蜡的时间，保障油井的正常生产。     

外输管线清蜡周期的确定

要确定合理的清蜡周期,就必须了解管线的蜡层厚度.目前主要根据站间压降反算管线平均蜡层厚度,这种方法相对简单,数据比较容易得到,但大多数管线沿线结蜡分布不均匀,使得根据压降反算得到的平均蜡层厚度和管线实际蜡层厚度偏差较大.利用结蜡分布函数模拟管线沿线结蜡规律这种方法比根据压降反算的平均蜡层厚度更接近管线沿线实际蜡层分布.该方法首先由管线一个清蜡周期的运行参数计算出清蜡后不同时间的平均蜡层厚度,然后利用从动态结蜡试验中得出的结蜡分布函数来计算管线沿线蜡层.从经济的角度考虑,建议阿赛输油管线夏季通球周期为90天,冬季通球周期为60天；从安全的角度考虑,建议阿赛输油管线夏季通球周期为60天,冬季通球周期为30天.     

石蜡沉积动力学的测量和预测

讨论了在模拟运行流动条件下测量蜡沉积速度的试验技术，介绍了改进后的试验室试验方法和计算模型，以此来预测管道中的蜡沉积速度和长期积蜡对管道压降与温度分布的影响。该计算模型除了适用于计算沿管道的瞬时沉积速度外，还能模拟管道运行中结蜡的长期影响。计算结果表明，结蜡厚度和温度是位置、沉积量和压降的函数，而这些又都是时间的函数。文章还对海洋管道的蜡沉积进行了实例研究。研究结果表明，以该计算模型预计的大部分蜡     

集输油管道中的结蜡与防蜡

文章阐述了集输油管道中的结蜡问题，分析了原油中蜡沉积物的基本组成、集输油管道结．蜡机理，总结了影响结蜡的因素，并概述了目前主要的防蜡技术。同时还介绍了防蜡剂的防蜡机理、类型以及油田集输油管道中常用的防蜡剂产品。     

任京线正反输运行长期不清管条件下的结蜡规律

针对任京输油管道正反输运行长期不清管的情况,通过比较现有结蜡模型的优缺点．建立了适用于大庆冀东混合原油的结蜡模型;考虑结蜡过程的周期性和时效性,研究了任京线的结蜡规律;利用两次任京线改线工程的现场实测结蜡厚度进行了验证,实测值与预测值的最大相对误差为15．8％;分析了任京线管壁蜡沉积物的基本物性和结构强度。研究成果为任京线安全清管提供了理论依据。     

大庆原油管输结蜡规律与清管周期的确定

在确定不同流态区管壁处剪切应力、蜡晶溶解度系数、径向温度梯度及管道沿线温降分布的基础上,回归建立了适用于描述大庆油田某两联合站间输油管道蜡沉积的结蜡模型。根据差压法原理,建立了研究原油管输结蜡过程室内模拟试验装置,并覆盖该输油管道的典型工况条件开展了管输原油结蜡模拟试验。相对偏差分析表明,结蜡模型预测结果与试验值的适配性良好。进而在预测运行时间对该输油管道结蜡影响的基础上,结合结蜡层厚度对管道轴向温降及压降的作用,确定了年季节最高与最低土壤温度期的清管作业周期分别为4个月和3个月。     

油井井筒结蜡原因及治理措施研究

针对油井井筒结蜡问题，对油井结蜡原因及规律进行分析，并提出合理的结蜡治理措施，为保障油井井筒的生产效率奠定基础。研究表明：介质的组分、井筒内的温度、井筒内外温度差等因素都将对井筒结蜡问题产生重要影响。因此，需要从化学清蜡、热洗清蜡以及化学清防蜡等角度入手，采取多种类型清防蜡措施，防止结蜡对井筒生产作业产生影响。     

沈—抚高凝油管道清管厚度计算

采用热力及水力计算公式，对沈—抚高凝油管道“结蜡”后的进出站油温、摩阻损失、热力损失、动力损失等进行计算，确定出清管厚度（即“结蜡”厚度）为２０～３０ｍｍ，确保了管道的安全合理运行。     

MATHEMATICAL MODELLING OF WAX DEPOSITION IN CRUDE OIL PIPELINES (COMPARATIVE STUDY)

In this research, wax deposition in different crude oil pipeline systems was studied. In oil pipelines, the main mechanism for wax appearance is the temperature change along the pipeline. A computer program was developed to simulate the wax precipitation phenomena. Temperature profile along the pipeline was determined and solid liquid equilibrium constant, wax mole fraction and wax thickness along the pipeline were calculated. This computer program was applied to different crude oil pipeline systems in Iraq (Baiji-Daura, Rumaila-Zubair-Fao and Hadttha-Rumailia). In Haditha-Rumaila crude oil pipeline system, it was observed that wax thickness after a year is approximately 0.1 mm and temperature declined from 303 K to around 300.5 K. The wax mole fraction after a year is approximately 0.2. The solid-liquid equilibrium constant for the first component around 0.228 and around 165 for the second component after a year. Similar results were observed in other crude oil pipeline systems studied.     

MATHEMATICAL MODELLING OF WAX DEPOSITION IN CRUDE OIL PIPELINES (COMPARATIVE STUDY)

ABSTRACT

In this research, wax deposition in different crude oil pipeline systems was studied. In oil pipelines, the main mechanism for wax appearance is the temperature change along the pipeline. A computer program was developed to simulate the wax precipitation phenomena. Temperature profile along the pipeline was determined and solid liquid equilibrium constant, wax mole fraction and wax thickness along the pipeline were calculated. This computer program was applied to different crude oil pipeline systems in Iraq (Baiji-Daura, Rumaila-Zubair-Fao and Hadttha-Rumailia). In Haditha-Rumaila crude oil pipeline system, it was observed that wax thickness after a year is approximately 0.1 mm and temperature declined from 303 K to around 300.5 K. The wax mole fraction after a year is approximately 0.2. The solid-liquid equilibrium constant for the first component around 0.228 and around 165 for the second component after a year. Similar results were observed in other crude oil pipeline systems studied.     

Study of wax deposition law by cold finger device

Wax deposits in oil pipelines can reduce the effective inner diameter of such pipelines, which may lead to pipeline blockage accidents. In this study, a cold finger experimental device was constructed, and eight groups of experimental scenarios under cold flow conditions were performed in accordance with field conditions. The effects of deposition time and cold and hot bath temperatures on wax deposition were investigated. Results show that when the cold bath temperature remains unchanged, and only the hot bath temperature increases, the deposition quality and rate of mixed waxy crude oil will initially decrease and then increase. During this period, the temperature that corresponds to the maximum deposition mass is the starting point of the wax precipitation peak.     

蜡晶析出对天然气水合物生成动力学特性的影响

深海含蜡油气混输管道在低温、高压的输送环境下,容易引发蜡晶与天然气水合物(以下简称水合物)共存的现象并相互影响,加重管道堵塞。为了探明蜡晶析出对水合物生成动力学特性的影响情况,采用正庚烷(n-C_7)与正二十八烷(n-C_(28))混合液模拟含蜡输送体系,应用高压可视化反应釜观察水合物生成动力学实验,结合水合物生成过程中的可视化图像,研究不同蜡含量对水合物成核时间、耗气量和耗气速率的影响规律。实验结果表明:(1)在274.15 K、3.5 MPa的实验条件下,蜡晶析出加快了水合物的成核和生长过程,在蜡晶浓度(ω)为3.3%的体系中,水合物诱导时间最快缩短了56.9%;(2)同一温度、压力条件下,蜡晶析出增大了气体消耗量,并且蜡晶析出量越多累计耗气量就越大,在ω为3.3%的体系中,最大气体耗气率增加了2.15倍;(3)同一温度、压力条件下,含蜡体系中水合物的生长速率远远高于不含蜡体系。结论认为,蜡的存在会加速水合物的生成,增加水合物的沉积量,加大管道堵塞风险;为了确保深水油气混输管道的输送安全,应及时清理管道内析出的蜡晶。     

Effect of drag reducer and pour point depressant on the wax deposition of crude oil pipeline

In this paper, the data of wax precipitation before and after the addition of the additives showed that the addition of the drag reducing agent (DRA) and the pour point depressant (PPD) cannot change the wax appearance temperature (WAT) of crude oil. When the dosage of DRA is small, the DRA cannot increase, stop, or slow down the precipitation of wax crystals. The addition of PPDs has no influence on the amount of precipitated wax crystals. From the GPC analysis, the molecular weight of the wax deposit samples in Linpu pipeline is from 500 to 76,800, which indicates that there is no enrichment of DRA in wax deposit samples. The results of IR show that the C?O group was not detected in the wax deposit sample of the Wei Jing pipeline, which indicates that there is no enrichment of the PPDs in wax deposit samples. The results showed that the DRA and PPD have no obvious effect on crude oil pipeline wax deposition.     

Prediction of Wax Deposition in an Insulation Crude Oil Pipeline

This study establishes an insulation crude oil pipeline wax deposition experimental device and describes the experimental method for insulation crude oil pipeline wax deposition. The experimental program is based on the operational plan of Tieling–Huludao insulation crude oil pipeline. The data are analyzed according to the effect of varying oil temperature, insulation thickness, and flow on wax deposition. Using SPSS software, a Daqing crude oil wax deposition rate model is derived from the linear regression. The use of the wax deposition rate model forecasts the wax deposition of the Tieling–Huludao insulation crude oil pipeline during different seasons.     

Study on the wax deposition of waxy crude in pipelines and its application

An experimental loop for the wax deposition study is established; a novel method to determine the thickness of the wax deposition in the experimental loop is developed, taking into account the impact of the instant temperature decreasing of the test section wall which leads to the increasing of the viscosity of the crude oil near the pipe wall and the distortion of the flow field in the pipe. The wax deposition characteristics of the QH crude are studied using the experimental loop. For the QH crude oil, there is a peak area of the wax deposition when it is 40 °C around. And very little deposition emerges when the temperature is not only higher than the wax appearance point but also lower than the temperature of solidification. It is also proved in the lab that the shearing dispersion of the wax crystal particles plays little role in the wax deposition when the shearing rate is high. The observation of the pipe which is cut in the field shows that the laying of the wax deposition in the pipe is very clear, and the wax deposition caused by the shearing dispersion exists clearly. From the angel of the shutdown temperature drop and safely restart for the hot oil pipeline, it is concluded that there is a permissible critical thickness of the sedimentary layer for the low flow rate pipelines.     

降凝剂对管输原油含蜡的处理作用

本文介绍了含蜡原油在管道输油过程中的结蜡过程,以及利用降凝剂降低含蜡原油析蜡点的机理,通过控制管道中原油的粘度达到有效地利用降凝剂的目的。     

可溶性管道清蜡化学球的研究

适用于DN70管道清蜡用的65mm化学球，是由乙烯醋酸乙烯酯、聚乙烯、萘、三聚磷酸钠和煤油复配而成。通过现场投球试验，化学球的强度试验、溶解性试验和降凝降粘试验，共筛选出7个较好的化学球配方。试验结果表明，采用化学球清除管道积蜡，具有不堵塞管道，并对原油起到一定的降凝降粘作用等优点，是一种简便易行、行之有效的清除管道积蜡的好方法。