电驱法低渗透岩石低速渗流规律研究

发布时间：2018-03-05 15:37

本文选题：低渗透岩　切入点：非达西渗流　出处：《中国地质大学》2016年博士论文　论文类型：学位论文

【摘要】：低渗透岩石低速渗流规律研究是当前渗流力学领域的研究热点,对油气开发、污染迁移、危废填埋等都具有重大意义。国内外学在研究过程中均发现低渗透岩体在低速渗流阶段其渗流曲线与达西定律有明显偏差,但因受限于实验方法和条件,难于获取岩体在低速渗流特别是启动阶段的实验数据,使得在低渗透岩体低速渗流机理和相关理论研究方面尚未形成统一观点。研究能够直接测量低渗岩体启动压力梯度和低速渗流状态的方法是当前低速渗流研究的重点和难点,对于开展低速非达西流研究具有重大的理论意义和实际作用。本文对低渗岩低速非达西流研究中低速渗流状态测量方法、低流速渗流实验方法、启动压力梯度测量方法以及低速非达西流机理等问题,运用理论分析和室内实验的方法展开了深入研究,完成了以下工作：1.以动力学手段分析电解极化过程,提出了采用电解极化示踪法测量低速渗流状态,设计实现了低速渗流传感器、测控系统及数据处理方法,并通过模拟实验证明了电解极化示踪法能够测量μL·min-1级别的低速渗流状态；2.从电动现象的原理出发,分析了电渗泵的原理及设计方法,设计制作了用于低速渗流实验的电渗泵,进行了电渗泵的性能实验。结果表明,该电渗泵的最大输出压力为1.179MPa、流量的分辨率为73.48nL·μL·min-1·V-1,能够在保证输出压力的前提下为低速渗流实验提供μL·min-1级别的稳定流量；3.根据电渗泵的工作原理,提出了运用电渗泵进行低速渗流实验的电驱法,介绍了电驱法基本步骤和启动压力梯度的测量方法,设计了相应实验装置及测控系统,并采用等径毛细管束模拟岩心和真实低渗砂岩岩心进行了低速渗流实验。结果表明,电驱法可以直接测量启动压力梯度,能够在μL·min-1级别流量条件下获取更多的渗流状态实验数据,等径毛细管束模拟岩心的渗流曲线为不过原点的直线、毛细管存在启动压力梯度,低渗砂岩岩心具有启动压力梯度、存在低速非达西渗流；4.结合前人的研究成果,提出了非等径毛细管束低速非达西渗流理论模型,给出了孔喉分布与渗流状态的关系,分析了不同孔喉分布条件下的低速渗流状态,并通过理论模型推导了流量与压力梯度的关系。结果表明,孔喉分布差异是导致低速非达西流的主要原因。论文提出的电驱法为低渗透岩体低速渗流实验及启动压力梯度测量提供了一种新的方法和技术手段,能够直接测量岩体的启动压力梯度、可以更好的观察岩体中μL·min-1级别流速时的渗流状态。建立的非等径毛细管束理论模型,将岩体内部孔隙结构特征与渗流规律相结合,能够较好表征不同孔喉特征时的低速渗流特征,为低速渗流规律研究提供了理论依据和方向指导,解释了岩体在低速渗流时的不同渗流特征,具有一定的理论价值和应用前景。
[Abstract]:The study of low-velocity seepage in low-permeability rock is a hot research topic in the field of seepage mechanics. It is very important for oil and gas development and pollution migration. It is found that the seepage curve of low-permeability rock mass in low-velocity seepage stage is obviously different from Darcy's law, but limited by experimental methods and conditions. It is difficult to obtain the experimental data of rock mass at low velocity seepage, especially in the start-up stage. Because of the lack of a unified view on the mechanism of low-velocity seepage in low-permeability rock mass and related theoretical research, it is an important and difficult point to study the method of measuring the starting pressure gradient and low-velocity percolation state of low-permeability rock mass directly. It is of great theoretical and practical significance for the study of low-velocity non-Darcy flow. In this paper, the low-velocity seepage state measurement method and the low-velocity seepage experimental method in low-permeability rock low-velocity non-Darcy flow study are studied. The starting pressure gradient measurement method and the mechanism of low-speed non-Darcy flow are studied in depth by using theoretical analysis and laboratory experiments. The following work has been accomplished: 1. The electrolysis polarization process is analyzed by means of dynamics. In this paper, the electrolytic polarization tracer method is used to measure the low speed percolation state. The low speed seepage sensor, measurement and control system and data processing method are designed and realized. It is proved by simulation experiment that electrolysis polarization tracer method can measure the low speed seepage state of 渭 L 路min-1 level. Based on the principle of electric phenomenon, the principle and design method of electroosmotic pump are analyzed, and the electroosmotic pump used in low speed seepage experiment is designed and manufactured. The performance experiment of electroosmotic pump is carried out. The results show that, The maximum output pressure of the electroosmotic pump is 1.179 MPA and the resolution of flow rate is 73.48 nL 路渭 L 路min-1 路V-1.It can provide a stable flow rate of 渭 L 路min-1 level for the low speed seepage experiment under the premise of ensuring the output pressure. According to the working principle of the electroosmotic pump, In this paper, an electroflooding method using electroosmotic pump for low speed seepage experiment is put forward. The basic steps of electric flooding method and the measuring method of starting pressure gradient are introduced. The corresponding experimental device and measurement and control system are designed. The experiments of low velocity percolation were carried out by using the equal-diameter capillary bundle to simulate the core and the true low-permeability sandstone core. The results show that the starting pressure gradient can be measured directly by the electroflooding method. Under the condition of 渭 L 路min-1 flow rate, more experimental data of seepage state can be obtained. The seepage curve of the core simulated by equal-diameter capillary bundle is a straight line with no origin, and the capillary has a starting pressure gradient, and the low-permeability sandstone core has a starting pressure gradient. There exists low speed non Darcy percolation. Based on the previous research results, a low speed non Darcy seepage model of non equal diameter capillary beam is proposed, and the relationship between pore throat distribution and seepage state is given. The low velocity percolation state under different pore throat distribution conditions is analyzed, and the relationship between flow rate and pressure gradient is deduced by theoretical model. The results show that, The difference of pore throat distribution is the main cause of low velocity non-Darcy flow. The electric flooding method proposed in this paper provides a new method and technical means for low permeability rock mass flow experiment at low speed and the measurement of starting pressure gradient. The starting pressure gradient of rock mass can be measured directly, and the seepage state of rock mass at 渭 L 路min-1 level velocity can be observed better. The non-equal-diameter capillary beam theory model is established, which combines the pore structure characteristics of rock mass with the seepage law. It can better characterize the characteristics of low-velocity seepage under different pore throat characteristics, provide theoretical basis and direction guidance for the study of low-velocity seepage law, explain the different seepage characteristics of rock mass under low-velocity seepage, and have certain theoretical value and application prospect.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU45

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