四川盆地周缘牛蹄塘组页岩微观孔隙结构特征

以四川盆地周缘地区下寒武统牛蹄塘组富有机质页岩为研究对象,通过X衍射全岩分析、低温液氮吸/脱附等实验方法技术对研究区页岩储层微观孔隙结构进行了系统研究;并探讨了控制纳米尺度微观孔隙结构的主要原因。结果表明:四川盆地周缘牛蹄塘组富有机质页岩矿物组分中石英、长石等脆性矿物含量较高,其次是黏土矿物;页岩微孔结构复杂,多为开放型空隙,以管状孔和平行壁的狭缝状孔为主;微观孔隙孔径主要分布在2~10 nm,以微孔为主。通过分析控制该区页岩储层微观孔隙结构的主要因素,认为有机碳含量是控制纳米级孔隙发育的主要因素,同时也是页岩气赋存的重要物质基础。

Characteristics of microscopic porestructures of Niutitang Formation in margin of Sichuan Basin

Taking the Niutitang Shale in margin of Sichuan Basin as the target, we systematically studied the microscopic pore structures of the shale reservoir by using minerals composition analysis,Nitrogen Sorption-Desorption technology. Based on all of these, discussed the main factors to control the nanopore structure. The results revealed that, the micropores mainly consist of cylinder pores with two open ends, slit type pore with parallel plates. Pore diameters are in the range of 2-10nm with micropore predominant. In addition, organic carbon content is believed to be the major factors controlling the development of nanopores of the shale reservoirs and also the important substance to for the occurrence of shale gas.