压实对页岩有机质孔隙发育控制作用——以四川盆地东南地区及周缘下古生界为例

Controlling effect of compaction upon organic matter pore development in shale: A case study on the Lower Paleozoic in southeastern Sichuan Basin and its periphery

陈前 闫相宾 刘超英 魏晓亮 程喆 秦伟军 洪太元

Qian Chen Xiangbin Yan Chaoying Liu Xiaoliang Wei Zhe Cheng Weijun Qin Taiyuan Hong

有机质孔隙是页岩储层中的重要储集空间，目前相关研究主要集中在孔隙的成因与描述上，而对地质条件下有机质孔隙所经历的次生压实改造关注较少。基于扫描电镜、孔隙定量统计和气体吸附技术，对川东南地区及周缘下古生界黑色页岩有机质孔隙的压实改造特点开展了研究。结果显示，有机质孔隙的变形与定向性排列为常见现象，其特征与有机质的赋存状态有关。顺层有机质中孔隙被压实破坏的现象最为普遍，充填有机质中的孔隙则局部被挤压发生形变，矿物集合体有机质孔隙的形变则主要与粘土矿物有关。除有机质赋存状态外，有机质孔隙被压实破坏的影响作用还受控于微观矿物格架的保护、由有机质含量所决定的岩石塑性以及有机质孔隙本身的大小。

Pores in organic matter are important storage space for gas or oil in shale. Present researches are focused more on the genesis and description of the pores and less on the secondary compaction that also plays a role in the modification of the pores under diverse geological conditions. This paper studies the modification of the pores under compaction with samples from the Lower Paleozoic black shale of southeastern Sichuan Basin and its periphery being observed with scanning electron microscopy (SEM) and analyzed with quantitative pore statistics and gas adsorption techniques. The results show that the deformation and orientation arrangement of pores commonly seen in the organic matter samples can be related to the actual occurrence of the organic matter: the pores are generally destroyed under compaction when in organic matter along beddings, or squeezed to deform locally when in organic matter serving as fillings in shale or just deformed by clay minerals when in organic matter-mineral aggregates. In addition to the occurrence, the pores are also affected by microscopic mineral framework, rock plasticity determined by organic matter content, and their own size.

10.11743/ogg20210107