均质流体及多孔介质温度分布的磁共振测量

发布时间：2018-03-01 09:26

  本文关键词： 磁共振成像 温度分布 多孔介质 均质流体 同步测量　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：碳封存(CCS, Carbon Capture and Storage)技术捕集二氧化碳、运输并将其封存于储层以缓解温室效应,特别是二氧化碳驱油技术,在减少二氧化碳排放量同时增产原油和天然气。本文利用磁共振成像技术测量了大体积均质流体及多孔介质的温度分布特性,探讨了大体积均质流体速度温度同步测量技术,研究成果可为CO2咸水层和二氧化碳强化采油封存场地安全性及高效性提供依据。具体研究内容如下：设计了测量均质流体及多孔介质内部温度分布和流体速度温度同步测量的实验系统,包括磁共振成像(MRI)、液体注入排出、温度监控、温度压力控制系统等。该系统可以精确控制样品的温度,并使用热电偶测量样品的温度及流动进出口温度,从而验证MRI温度测量精度,该实验平台可用于确定均质流体和多孔介质的速度温度分布。利用磁共振成像技术,标定了纯水、饱和二氧化碳水及正癸烷大体积均质样品的纵向弛豫时间、纵向平衡磁化强度及自扩散系数与温度的关系。实验结果表明一定温度范围内这三个参数均与温度存在良好的线性关系,自扩散系数法测量均质流体样品精度最高、温度敏感度最高；而纵向弛豫时间法和纵向平衡磁化强度法测量均质流体样品温度分布耗时较长,精度有限。随后利用自扩散系数法测量纯水样品冷却过程中的温度分布,随着温度梯度的减小,测得的流体温度变化减慢且核磁管壁面温度低于样品中心。开发了磁共振成像同步测量流体温度速度的技术,开展了测量不同流速下流体的速度温度实验,获得了不同速度分布及温度分布图。用FLUENT模拟同实验条件下的速度分布及温度分布,模拟结果表明该方法不仅可以可视化流场速度分布,而且可以获得较高精度温度测量结果,温度测量误差在2℃以内。模拟结果与实验测得的温度速度场结果吻合很好。开发了多孔介质内流体温度分布的测量方法,研究了多孔介质内饱和水的自扩散系数、纵向弛豫时间与温度关系特性,并用自扩散系数法得到多孔介质冷却过程的降温趋势图和温度分布图,MRI自扩散系数法测量的温度值与热电偶测量值误差基本在1℃以内,探析了多孔介质内温度分布特性。本研究确立了MRI技术测量均质流体及水饱和多孔介质温度分布的有效性,能准确地得到储层岩心的微观孔隙结构和多孔介质模拟岩心的温度分布,为以后详细研究多孔介质和均质流体内的传质传热特性提供了重要实验方法和实验手段、为二氧化碳封存的高效及安全性提供了保障。
[Abstract]:CCS (Carbon Capture and Storage) technology traps, transports and stores carbon dioxide in reservoirs to ease Greenhouse Effect, especially carbon dioxide displacement. In this paper, the temperature distribution characteristics of large volume homogeneous fluid and porous medium are measured by magnetic resonance imaging, and the simultaneous measurement technology of velocity temperature of large volume homogeneous fluid is discussed. The research results can provide the basis for the safety and efficiency of CO2 salt water layer and CO2 enhanced oil recovery storage site. The specific contents of the study are as follows: the temperature distribution and velocity temperature in homogeneous fluid and porous media are measured. An experimental system for synchronous measurement, This system can accurately control the temperature of the sample, and use thermocouple to measure the temperature of the sample and the inlet and outlet temperature of the flow. The experimental platform can be used to determine the velocity and temperature distribution of homogeneous fluid and porous media. The pure water is calibrated by magnetic resonance imaging. Longitudinal relaxation time of saturated carbon dioxide water and decane bulk homogenized samples, The experimental results show that there is a good linear relationship between the three parameters and temperature in a certain temperature range, and the self-diffusion coefficient method has the highest accuracy in measuring homogeneous fluid samples. The temperature distribution of homogeneous fluid samples measured by the longitudinal relaxation time method and the longitudinal equilibrium magnetization method is the highest, and the temperature distribution in the cooling process of the pure water sample is measured by the self-diffusion coefficient method. With the decrease of temperature gradient, the measured fluid temperature changes slowly and the wall temperature of nuclear magnetic tube is lower than the center of the sample. A technique for simultaneous measurement of fluid temperature velocity by magnetic resonance imaging (MRI) is developed. In this paper, the velocity and temperature distribution of fluid at different velocity is measured, and the velocity distribution and temperature distribution are obtained. The velocity distribution and temperature distribution under the same experimental conditions are simulated by FLUENT. The simulation results show that this method can not only visualize the velocity distribution of the flow field, but also obtain high precision temperature measurement results. The temperature measurement error is less than 2 鈩，

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