摘要
为了揭示黏土矿物在含气页岩储层中所扮演的角色，选择以不同黏土矿物为主的黏土岩进行了孔隙～表面积测量和甲烷等温吸附实验。测量显示，黏土矿物以3～100nm微孔隙为主，并出现3～6nm和20～70hm2个主要分布区。其中，蒙脱石黏土以小孔占优势，伊／蒙混层黏土以小孔和中一大孔同时发育为特征，高岭石、绿泥石和伊利石黏土均以中一大孔为主。蒙脱石、伊／蒙混层和高岭石黏土为孔隙发育类型，总孔隙体积和表面积分别达到0．04mL／g和11．47m^2／g以上。不同类型黏土岩的甲烷吸附能力有较大差异，利用朗格缪尔方程拟合计算的蒙脱石黏土、伊／蒙混层、高岭石黏土、绿泥石黏土、伊利石黏土、粉砂岩及石英岩小于270目试样的最大甲烷吸附容量分别为8．12mL／g、3．66mL／g、2．70mL／g、2．28mL／g、1．72mL／g、0．97mL／g和0．70mL／g。黏土岩的表面积不仅取决于总孔隙体积和孔隙率，而且与孔隙尺寸的分布关系更为密切。黏土岩中小于100nm微孔隙体积与甲烷最大吸附量显示良好的线性关系，因此，页岩微孔隙体积的大小反映其天然气的吸附能力，而气体吸附能力的大小受其内孔隙，特别是小于20nm微孔隙发育程度的控制。不同黏土矿物由于形态结构、孔隙大小和孔隙率的不同，导致其气体吸附性上的差异，而这种差异不仅与黏土的类型有关，而且受岩石成因和成岩作用的影响。
The pore size, surface area and methane adsorption isotherm of clay-rich rocks are measured. Clay minerals mainly contain micropore of 3-100nm,and have two main intervals of 3-6nm and 20-70nm. Smec- rite is of micropore-dominant. Illite-smectite mixed layer developed micropore and macropore in the same time,and kaolinite, chlorite and illite are of mesopore and macropore. Smectite, illite-smectite mixed layer and kaolinite are the polyporous type, their total pore volume and surface area are more than 0.04 mL/g and 11.47mZ/g,respectively. Adsorption capacity of clay rocks is quite different. The maximum methane adsorption capacity of smectite, illite-smectite mixed layer, kaolinite, chlorite, illite, sandstone and quartzite in the granularity of less than 270 mesh sequentially are 8.12 mL/g,3.66 mL/g,2.70 mL/g,2.28 mL/g, 1.72 mL/g,0.97 mL/g and 0. 70 mL/g. Surface area of clay minerals depends not only on the total pore volume and porosity,also on the pore size distribution closely. There is a good linear relationship between the micropore volume of clay minerals and the maximum amount of methane adsorption. Therefore, the mi- cropore volume of shale reflects its adsorption capacity for natural gas. The adsorption capacity is con- trolled by the development degree of internal micropores, in particular less than 20nm micropores. The difference of clay minerals in morphological structure, pore size and porosity results in the differences of their adsorption capacity. This difference is associated not only with the clay type,also with its causes and the diagenesis experienced.
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2014年第2期141-152,共12页
Natural Gas Geoscience
基金
国家科技重大专项(编号:2011ZX05008-002-22)
国家重点基础研究"973"计划(编号:2012CB214704-02)联合资助
