拟静水压力条件下二氧化碳驱替煤层瓦斯试验研究

发布时间：2018-05-07 06:04

本文选题：煤层气 + 二氧化碳　；参考：《太原理工大学》2013年硕士论文

【摘要】：煤层气是一种自生自储的非常规天然气,是近30年来新兴的、蕴藏量巨大的潜在能源之一。我国的煤层气资源十分丰富,但由于煤层渗透率普遍低于工业化开采条件,常规开采方法在国内的应用受到限制。针对我国煤层自身特点,建议采用二氧化碳驱替煤层瓦斯技术,以提高煤层气的采收率,同时可将二氧化碳储存于煤层中,减少对大气的污染。本文首先研究与总结了气体在煤层中的吸附、解吸以及运移机理,分析了温度、体积应力、气体压力对气体储存与运移的影响,对二氧化碳与甲烷在煤层中的置换、驱替过程进行了理论研究。在此基础上,使用大尺寸(100mm X100mm X200mm)贫瘦煤试件,进行了拟静水压力下渗透率测定试验与二氧化碳驱替甲烷试验研究。渗透试验结果表明：室温条件下,气体在煤体中的渗透率受静水压力与渗透压双重影响。煤体处于静水压力环境时,其内部收缩变形比较均匀,未有剪切破坏发生,其物理特性更接近于各向同性多孔介质,回归分析发现,渗透压力不变时,随着静水压力的增加,渗透率呈现负指数规律衰减,主要由静水压力的加载导致煤体的收缩变形作用引起；体积应力不变时,随渗透压增加渗透率的降低存在最小值,此后随着渗透压增大,渗透率开始上升。置换与驱替试验结果表明：二氧化碳对贫瘦煤中所吸附甲烷的置换比为1.43-2.17,表现为体积应力越小,置换比越高；同时温度对置换过程有重要影响,温度越高置换效果越好。在不同体积应力与驱替压力下,三个试件中,二氧化碳对瓦斯的驱替效率分别为57.1%、40.3%、43.9%,驱替效率受体积应力与驱替压力双重影响,其中体积应力下降将导致驱替效率上升,而驱替压力上升将导致驱替效率下降。同时与前人工作对比发现,驱替压力对驱替效率的影响最为显著。
[Abstract]:Coal bed methane (CBM) is a self-generated and self-stored unconventional natural gas, which is one of the potential energy sources in recent 30 years. The coal bed methane resources in China are very rich, but because the coal seam permeability is generally lower than the industrial mining condition, the application of conventional mining method in China is limited. According to the characteristics of coal seams in China, it is suggested that carbon dioxide displacement technology should be used to improve the recovery efficiency of coalbed methane and to store carbon dioxide in coal seams to reduce atmospheric pollution. In this paper, the mechanism of gas adsorption, desorption and migration in coal seam is studied and summarized. The effects of temperature, volume stress and gas pressure on gas storage and migration are analyzed, and the displacement of carbon dioxide and methane in coal seam is analyzed. The displacement process is studied theoretically. On this basis, the permeability measurement test and carbon dioxide displacement test of methane under pseudohydrostatic pressure were carried out using the lean coal sample with a large size of 100mm X100mm x 200mm. The results of permeability test show that the permeability of gas in coal is influenced by hydrostatic pressure and osmotic pressure at room temperature. When the coal body is in hydrostatic pressure environment, its internal shrinkage and deformation are more uniform, no shear failure occurs, and its physical characteristics are closer to isotropic porous media. Regression analysis shows that the static water pressure increases with the constant permeation pressure. Permeability shows negative exponential attenuation, which is mainly caused by shrinkage and deformation of coal body caused by hydrostatic pressure. When volume stress is constant, the decrease of permeability is minimum with the increase of osmotic pressure, and then increases with osmotic pressure. The penetration rate began to rise. The results of displacement and displacement tests show that the replacement ratio of carbon dioxide to methane adsorbed in lean coal is 1.43-2.17, which shows that the smaller the volume stress, the higher the displacement ratio, and the more the temperature is, the better the displacement effect is. Under different volume stress and displacement pressure, the displacement efficiency of carbon dioxide to gas is 57.1 / 40.3and 43.9, respectively. The displacement efficiency is affected by volume stress and displacement pressure, and the decrease of volume stress will lead to the increase of displacement efficiency. The displacement efficiency will decrease when the displacement pressure rises. At the same time, it is found that displacement pressure has the most significant effect on displacement efficiency.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TD712.6

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