超声波作用下的煤层气吸附一解吸规律实验  

Experiment on CBM adsorption-desorption rules under the effect of ultrasonic pressure waves

作　　者：赵丽娟[1] 

机构地区：[1]山西大同大学煤炭工程学院

出　　处：《天然气工业》2016年第2期21-25,共5页Natural Gas Industry

基　　金：国家科技支撑计划(编号:2012BAK04B00);大同市基础研究计划项目(编号:2015113)

摘　　要：目前,对于超声波作用下的煤层气吸附—解吸规律及超声波促进煤层气解吸机理的研究还有待于进一步深入。为此,利用自行设计的实验平台,开展了超声波作用下的煤样等温吸附—解吸实验(实验煤样采自山西晋城成庄煤矿和高平建业煤矿的下二叠统山西组15号煤层)。实验结果显示,未加载超声波时,伴随着压力的逐渐增大,煤样对CH_4的吸附量逐渐增加;但在加载超声波后,随着超声波功率的增大,煤样的吸附能力逐渐减弱,且随着系统压力的释放,煤样的解吸速率逐步增大。超声波使得煤样吸附能力降低的原因主要在于:①超声波的热效应使得煤样内部温度升高,降低了煤样的吸附能力:②煤岩表面势能的提高以及超声波作用下色散力的产生,使得CH_4气体分子被吸附的概率降低。而煤样解吸速率增大的原因可解释为:在施加超声波的情况下,煤体内部质点发生微位移并产生新的裂隙、微裂隙和孔隙,从而促进了煤层气的解吸和扩散。结论认为:超声波功率与煤样Langmuir常数呈负相关关系,利用所得到的实验数据可以拟合Langmuir常数与超声波功率之间的函数关系,据此可建立超声波与煤岩吸附特性之间的数值关系。For the identification of the CBM adsorption-desorption rules and the mechanism of CBM desorption under the effect of ultrasonic waves, isothermal adsorption-desorption experiments were carried out on coal samples by using the independently designed experimental platform. The samples were taken from No. 15 coalbed of the Lower Permian Shanxi Fm in Chengzhuang Coal Mine and Gaoping Construction Coal Mine, Jincheng, Shanxi Province. Experimental results show that the CH4 adsorption of samples increases gradually with the increasing of pressure if no ultrasonic pressure waves are applied. However, the adsorptive capacity reduces gradually with the increasing of ultrasonic power if applied. And with the release of the system pressure, the desorption rate of coal samples increases gradu- ally. Such reduction of adsorption capacity is mainly attributed to two aspects. Firstly, due to the heat effect of ultrasonic waves, the internal temperature of coal samples rises and the adsorptive capacity decreases. And secondly, the surface potential of coals increases and the dispersion force is generated under the effect of ultrasonic pressure waves. Based on the interpretation, CBM desorption and diffusion are promoted, because mass points inside the coal bodies experience micro-displacement under the effect of ultrasonic waves and meanwhile cracks, micro-cracks and pores are newly formed. It is concluded that the ultrasonic power is negatively related with the Langmuir con- stant of coal samples. With the experimental data, the function relations between Langmuir constant of the coal samples and the ultrasonic power are fitted. In this way, the numerical relationship is established between the ultrasonic pressure waves and the coal adsorption.

关 键 词：实验室试验 煤层气 超声波 吸附 解吸 Langmuir常数 热效应 物性参数 函数 

分 类 号：TE37[石油与天然气工程—油气田开发工程]