四川盆地海相富有机质页岩孔隙特征及赋存状态特征

本文利用低温液氮吸附实验和扫描电子显微镜,基于分子动力学研究了龙马溪组页岩的孔隙特征和甲烷生成特征。根据低温液氮吸附的BET模型,龙马溪组页岩的比表面积为4.32-29.50 m² / g,平均为13.78 m² / g。计算得出的页岩总孔隙体积为6.12-30.47cm³ / g,平均孔径分布范围为3.83-4.52nm,平均孔径为4.06nm。页岩气的吸附和生成也很容易与人工压裂产生的裂缝形成有效的连通。输送通道相对平滑,气体渗透条件良好,这有助于页岩气的开发。孔类型主要包括微裂纹,粒内孔和粒间孔。龙马溪组页岩储层中甲烷的吸附特性表明,随着孔径的变化,甲烷的吸附势能由正向负变化,并逐渐趋近于零。零点表示没有甲烷分子吸附在孔壁上。爆发从吸附变为自由。

Pore characteristics and occurrence characteristics of marine organic-rich shale in the Sichuan Basin

As a new unconventional energy source in the 21st century, shale gas has huge reserves in the Longmaxi Formation in the Sichuan Basin. This paper studies the pore characteristics of the Longmaxi Formation shale based on molecular dynamics by conducting low temperature liquid nitrogen adsorption experiments and scanning electron microscopy. And the study of methane occurrence characteristics. The conclusion is as follows: the maximum relative pressure p/p0 of the nitrogen adsorption of the Longmaxi Formation shale is about 0.99, and the total amount of adsorbed gas under this condition is considered to be the pore volume of the sample to be tested. The specific surface area of the study area shale in the BET model is 4.67 ~ 31.50 m² / g, with an average of 14.78 m² / g. The total pore volume of the shale is calculated to be 6.12~30.47cm³/g, the average pore size distribution range is 3.83~4.52nm, and the average pore diameter is 4.06nm. The adsorption of shale gas is also easy to form an effective communication with the crack generated by artificial fracturing. The migration channel is relatively smooth, and the gas seepage conditions are better, which is conducive to the exploitation of shale gas. The pore types mainly include micro-cracks, intragranular pores and intergranular pores. The characteristics of methane adsorption in the shale reservoir of Longmaxi Formation show that the potential of methane adsorption changes from positive to negative and then zero. When it reaches 0, it indicates that the pore wall has no adsorption to methane molecules. Has changed from an adsorption state to a free state.