焦石坝地区龙马溪组页岩有机质孔隙特征

页岩气作为非常规天然气,其载体页岩为低孔低渗的致密岩,天然气在致密的页岩中的赋存形式、储存场所及富集机理一直是地质家们研究的问题。对川东南焦石坝龙马溪组富有机质页岩储层研究过程中,发现页岩中除了常规储层中常见的孔隙类型外,有机质颗粒内孔隙发育程度很高。通过扫描电镜观察、氮气吸附以及大量测试分析资料综合研究认为,焦石坝龙马溪组富有机质泥页岩富含无机孔隙和有机孔隙,有机孔隙是页岩中优势孔隙类型,发育程度具有非均质性,形态多样,平面上通常为泡泡状、似椭圆状、港湾状及其他不规则形状,孔径范围2～900 nm不等。另外,有机质微小的孔隙、粗糙的表面特性,为吸附甲烷提供了比表面积,其亲油（气）的特性使其优先吸附、储集天然气,对页岩气富集起了重要作用。

Pore Characteristics of Organic Matter in Shale of Longmaxi Formation,Jiaoshiba Area

For shale gas,a kind of unconventional gas,the carrier of shale is just low-permeability and low-porosity tight rock.Its modes of occurrence,storage place,accumulation mechanism are the problems studied by geologists.After a study on the Longmaxi shale reservoir with rich organic matter,Jiaoshiba area in southeastern Sichuan Basin,it is found that,in addition to common porous types discovered in conventional reservoirs,the growth of pore within organic-matter particle is the highest in the shale.Moreover,after another comprehensive study on the SEM observation and the nitrogen absorption testing,it is deemed that（1） in mud shale with abundant organic matter in Longmaxi Formation,rich inorganic and organic pores are always found;and（2） for organic pore,the major kind,the growth is characterized by heterogeneity,various shapes（bubble,quasi-ellipse,harbor,and other irregularity in shape often found on plane）,and pore radius ranging from 2 to 900 nm;（3） pore with tiny organic matter and tough surface may provide specific surface area for methane adsorption,which its features of oil-or gasprone make pore adsorb and store gas priority,playing an important role in shale-gas accumulation.