摘要
采用扫描电镜、低温氮吸附实验相结合的方法,对大庆探区重点含煤盆地煤岩孔隙类型进行识别,探讨不同变形程度下煤岩分形维数与孔隙结构、气体吸附能力和构造位置之间的关系。研究表明:原生结构煤中孔隙以植物组织孔为主,孔隙相对独立;构造煤中孔隙以气孔和溶蚀孔为主。随着变形程度的增加,开启裂缝大量出现,增加了孔隙之间的连通性,提高了煤岩孔隙的渗流能力。将大庆探区煤岩低温氮吸附曲线划分为3种类型,其中大量"墨水瓶"状孔的出现是造成煤岩吸附能力差异的主要原因。构造煤的分形维数较原生结构煤高,褶皱发育区的煤分形维数最大,煤岩变形程度较强,微孔含量增加,孔径变小,比表面积以数量级增大,孔表面粗糙度增加,为甲烷分子提供了更多的赋存空间,增强了煤岩的吸附能力。褶皱发育区在今后煤层气勘探中应给予足够的重视。
Scanning electron microscope and low-temperature nitrogen adsorption method are combined to identify pore types of coal in Daqing exploration area and to analyze the relationship between the fraetal dimension and the pore struc- ture, gas adsorption capacity and structural location in different deformation grade. The results indicate that the pore in coal of original structure is dominated by plant tissue pores independent of each other, while the pore in tectonic coal is gas pore and solution pore. There are a lot of open fracture accompanied by increasing deformation grade, improving pore connectivi- ty and permeability. There are three types of low-temperature nitrogen adsorption curves in Daqing exploration area, and a large number of ＂inkbottle＂ pores are main cause of great difference in adsorption capacity of coal. The fractal dimension of tectonic coal is higher than that of original coal, and it is the highest in fold area. As deformation grade gets stronger, micro -pore content increases, pore diameter gets smaller, specific surface area rises by orders of magnitude, and pore surface gets rougher, offering more occurrence of space for methane molecules and enhancing adsorption capacity of coal. Fold area should be paid more attention in later CBM exploration.
出处
《非常规油气》
2015年第3期13-21,共9页
Unconventional Oil & Gas
基金
中国石油天然气集团公司科技攻关项目"煤层气勘探开发关键技术研究与示范工程"(2010E-2201)
"大庆探区非常规油气勘探开发关键技术研究与现场试验"(2012E-2603)
关键词
大庆探区
孔隙特征
低温氮吸附实验
分形维数
吸附能力
Daqing exploration area
pores characteristics
low-temperature nitrogen adsorption experiment
fractal di-mension
adsorption capacity
