煤层中一氧化碳的渗透规律研究

发布时间：2018-05-12 09:09

本文选题：渗透率 + 围压　；参考：《河北联合大学》2014年硕士论文

【摘要】：火灾事故不仅危害职工安全也浪费大量优质煤炭资源，给国家带来了难以估计的损失，研究如何准确的预测预报煤矿火灾也成为矿井安全的重点。煤层中产生的CO来自于煤层中自然发火或其它火灾，还有一部分来源于煤层伴生，现阶段对于煤层赋存CO的研究刚刚开始。CO的出现与运移和煤储层渗透性有直接或间接的关系。煤层渗透性受到煤的变质程度、煤岩孔隙结构、外界围压、温度变化和气体压力等方面影响。实验研究发现：随煤变质程度的增加固定碳和灰分而升高，挥发分含量随煤变质程度的升高而降低。分形维数D1随着煤级的升高而出现递减的趋势，可以验证煤中大、中孔隙因煤级的升高而减小。当外界温度和气体压力保持恒定时，随着围压的增加CO气体通过煤层的渗透率逐减变小；并存在一个临界点，过了这一点又有增加的趋势。主要是由于随围压变大而有效应力随之变大，使得煤样内孔隙裂隙先被压缩变小之后趋于稳定，最后渗透率趋于稳定。当外界压力和气体压力保持恒定时，环境温度的升高导致煤层渗透率的相对减小。因为外界有压力的作用，使得高温产生的膨胀作用不能向外延伸，转而向内作用，挤压孔隙，致使流体通道变窄，，流速降低，渗透率变小。当外界压力和温度都保持恒定时，在气体压力P小于1.5MPa时，随着孔隙气体压力的增加煤层渗透率越来越小；当煤体通过有动力源的气体时，在高气压下渗透率又随着气压的升高而升高。
[Abstract]:Fire accident not only endangers the safety of workers but also wastes a large number of high-quality coal resources, which brings the country a loss that is difficult to estimate. The research on how to accurately predict and forecast the coal mine fire has also become the key point of mine safety. The CO produced in coal seam comes from spontaneous combustion or other fire in coal seam, and some comes from coal seam associated with CO. At present, the occurrence of CO in coal seam has a direct or indirect relationship with migration and permeability of coal reservoir. Coal seam permeability is affected by coal metamorphism, coal pore structure, external confining pressure, temperature change and gas pressure. The experimental study found that: With the increase of coal metamorphism, the fixed carbon and ash content increased, and the volatile matter content decreased with the increase of coal metamorphic degree. The fractal dimension D1 decreases with the increase of coal rank. It can be proved that the coal is large and the porosity decreases with the increase of coal grade. When the external temperature and gas pressure remain constant, the permeability of CO gas through coal seams decreases gradually with the increase of confining pressure, and there is a critical point, over which there is an increasing trend. The main reason is that the effective stress increases with the increase of confining pressure, which makes the pore fissure in the coal sample become smaller first and then stabilize, and finally the permeability becomes stable. When the external pressure and gas pressure remain constant, the increase of ambient temperature leads to the relative decrease of coal seam permeability. Because of the external pressure, the expansion produced by high temperature can not extend outward, but inwards, squeezing the pores, causing the fluid channel to narrow, the velocity of flow to decrease, and the permeability to become smaller. When the external pressure and temperature remain constant, when the gas pressure P is less than 1.5MPa, with the increase of pore gas pressure, the permeability of coal seam becomes smaller and smaller, and when the coal body passes through the gas with power source, At high pressure, the permeability increases with the increase of pressure.
【学位授予单位】：河北联合大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TD75

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