摘要
煤层气的勘探开发已逐步转向埋深大于1 000m的煤层,以沁水盆地南部为研究背景,采集浅部与深部煤样,进行压汞和低温氮吸附实验,对比孔隙结构特征.结果表明：从浅部到深部,煤层微小孔的体积稍增多,中孔和大孔的略减.当煤层埋深小于750m,压汞曲线类型以Ⅱ型为主,孔隙形态以Ⅰ类开放孔为主,孔隙结构配置较好.当煤层埋深为750~1 100m,压汞曲线类型包括Ⅱ型和Ⅲ型,孔隙形态以Ⅱ类一端封闭型为主,孔隙结构复杂,存在一个过渡带.当煤层埋深大于1 100m,压汞曲线类型以Ⅲ型为主,孔隙形态主要为Ⅰ类开放孔,含有部分Ⅱ类和Ⅲ类孔,气体储存空间减小,孔隙结构配置较差.地应力是影响孔隙结构的关键因素,随着埋深的增大,地应力的分带性导致孔隙结构由较好,变为复杂的过渡带,最后变为较差.深煤层的过渡带物性参数显示较为复杂的变化特征,为深部煤层气的开发提供参考依据.
The exploration and exploitation of coalbed methane(CBM)have gradually turned into deep coal seams(beneath one thousand meters).Taking the southern Qinshui basin as the researching background,collecting shallow and deep coal samples and integrating with mercury injection and low temperature nitrogen adsorption experiments,this paper analyzes the difference of pore structure between shallow and deep coal seams.The results show that,with the increase of depth of the coal seams,the number of tiny pores increases slightly,but the number of mesopores and macropores decreases.If the depth is less than 750 m,the mercury curve is mainly typeⅡ,and the pore shape is mainly typeⅠ.The pore structure configuration is the best.When depth is between 750 mand 1 100 m,the pore structure is more complicated.The mercury curve has both typeⅡ and typeⅢ,and the pore shape is mainly typeⅡ.If the depth greater than 1 100 m,the mercury curve is mainly typeⅢ,and the poor morphology has3 types,but mainly type Ⅰ.The crustal stress is the key factor,which affecting the pore structure.With the depth increase,crustal stress is divided into 3zones,resulting in the pore structure from better into a complex transition zone,and finally becomes poor.In a word,the deep coal seam has a transition zone,and in this zone,the coal reservoir property is complicated variety.It is suggested that,during the exploitation of deep coal seams,we must take in corresponding measures.
出处
《东北石油大学学报》
CAS
北大核心
2015年第3期41-49,3-4,共9页
Journal of Northeast Petroleum University
基金
国家科技重大专项(2011ZX05042)
关键词
深煤层
孔隙结构
孔隙形态
压汞曲线
低温氮吸附
过渡带
deep coal seam
pore structure
pore morphology
mercury injection curve
low temperature nitrogen adsorption
transition zone
