岩浆岩环境煤层瓦斯异常赋存特征与动力灾害防控关键技术

Abnormal coal seam gas occurrence characteristics and the dynamic disaster control technologies in the magmatic rock intrusion area

  • 摘要: 为研究岩浆岩赋存环境对煤层瓦斯动力灾害的影响,综合理论分析、实验室试验、多手段数值模拟、工程实践等方法,对岩浆岩侵入煤系地层后的热变质作用特征、煤体化学结构和物理规律变化特性等进行了系统研究与对比分析,并探讨了岩浆岩赋存环境下煤岩瓦斯动力灾害发生机制及防控关键技术。结果表明:(1)岩浆冷却-向围岩传热的散热方式为热传导,其热演化和接触变质作用不仅提升了煤体的变质程度并使其呈现自然分区特征,还导致煤体内部脱氧、去氢、富碳的趋势逐渐明显;(2)岩浆岩侵入煤系地层后,构造应力叠加热演化作用易造成影响区内煤体发生构造煤化,导致煤中孔容和比表面积增大,对瓦斯的吸附解吸能力亦增强;(3)岩浆岩赋存环境中煤体发生“二次生烃”,而致密低渗岩床的圈闭作用进一步提高了异常应力环境下伏煤层的瓦斯含量和瓦斯压力,增大了其煤与瓦斯突出危险性;(4)煤炭开采导致厚硬岩浆岩床失稳破断产生的冲击载荷作用于下伏含瓦斯煤层后,应力叠加等同于加大了煤层埋深并使煤体产生塑性破坏,能量叠加使得煤体灾变潜能提高,是导致煤层瓦斯动力灾害发生的主要因素。在上述研究基础上,结合岩浆岩赋存环境中煤层及其瓦斯赋存特征,建立了煤岩动力灾害预测敏感指标体系,并提出了煤层瓦斯动力灾害防控关键技术。

     

    Abstract: To study the effect of magmatic rock occurrence on coal gas dynamic disasters, the thermal metamorphism of magmatic rocks intruding into coal measure strata and the variation of coal chemical structural and physical properties are studied comprehensively using the methods of theoretical analysis, laboratory testing, numerical simulation and engineering practice. Then, the mechanism of coal and rock gas dynamic disasters under the conditions of magmatic rock occurrence is discussed and the key control technologies are proposed. The results show that(1) the magma cools and transfers heat to the surrounding rocks through the heat conduction. The thermal evolution and thermodynamic contact metamorphism of magma not only increase the metamorphic grade and make it present the characteristics of zoning distribution, but also result in that the trend of deoxidation, dehydrogenation and carbon enrichment in coals become gradually evident.(2) The tectonic stress caused by the magmatic rock intrusion and the thermal evolution of magma is easy to cause the tectonic coalification of the underlying coal seams and the pores in coals are severely damaged. These result in the increase of the coal pore volume and specific surface area, and the enhancement of the ad-/desorption ability of coals to gas.(3) In the magmatic rock occurrence area, the secondary hydrocarbon generation in coals and the trap effects of the tight magmatic rocks result in that the gas content and gas pressure of the underlying coal seams increase greatly, which increases the risk of the coal and gas outburst.(4) When the impact load produced by the thick and hard magmatic rocks breakage is applied to the underlying coal seams, the stress superposition is equivalent to the increase of the buried depth of coal seams and causes the plastic failure of coals. In addition, the energy superposition makes the potential disaster-causing energy of coal and gas increase, which is the main factor of the coal gas dynamic disaster. On this basis, the sensitive index system and the control technologies for the accurate prediction of coal and rock dynamic disasters in the magmatic rock intrusion area were put forward combining with the occurrence characteristics of coal seams and gases.

     

/

返回文章
返回