煤层气抽采过程中煤储层参数动态响应物理模拟

Dynamic Response Physical Simulation of Coal Reservoir Parameters During Coalbed Methane Drainage

针对在煤层气抽采工程现场难以对煤储层参数动态响应进行深入研究的问题,提出了基于物理相似模拟技术,采用真实煤样建立相似物理模型,试验研究煤层气抽采过程中煤储层参数动态响应特征的方法,并利用自主研制的煤层气抽采物理模拟试验系统,开展了三维应力状态下单一储层煤层气抽采物理模拟试验,初步获得了煤储层抽采流量、气体压力、流场及温度等参数的动态演化规律:抽采流量在抽采初期急剧增大,然后逐渐降低;距离钻孔越近气体压力下降越快;靠近钻孔处气体流速较大;抽采初期,煤储层温度变化量小,抽采后期,随着吸附气体的解吸,温度变化量逐渐增大。研究结果可为数值模拟和煤层气抽采工程设计提供基础参数和理论依据。

According to the detail study on the evolution of the coal reservoir parameters hard to be conducted in the coalbed methane drainage project site,based on the physical simulation technology,real coal samples were applied to establish a similar physical model to experience and study the dynamic response feature method of the coal reservoir parameters during the coalbed methane drainage process.An independent research and developed physical simulation experiment system of the coalbed methane drainage was applied to the physical simulation experiment of the coalbed methane drainage in a single seam under a 3D stress condition.The dynamic evolution laws of the coal reservoir gas drainage flow,gas pressure,flow field,temperature and other parameters were obtained preliminarily.The gas drainage flow was sharply increased in the initial gas drainage period and then was steadily decreased.The gas pressure with a distance more closed to the borehole would be decreased more rapidly.The velocity of the gas flow closed to the borehole was high.At the initial gas drainage period,the temperature variation of the coal reservoir was small and in the late drainage period,with the desorption of the absorption gas,the temperature variation would be steadily increased.The study results could provide the basic parameters and theoretical basis to the design of the numerical simulation and the coalbed methane drainage project.