下寒武统页岩孔隙结构与分形特征

Pore structure and fractal characteristics of Lower Cambrian shales

王濡岳 尹帅 龚大建 王冠平 杨滔 尚素芹6

中国石化石油勘探开发研究院，北京 100083 西安石油大学地球科学与工程学院，陕西 西安 710065 铜仁中能天然气有限公司，贵州 铜仁 554300 中国地质大学（北京）能源学院，北京 100083 中国石油大学（北京）地球科学学院，北京 102249 中国石化中原油田分公司濮东采油厂，河南 濮阳 457001

利用低温氮气吸附、矿物学与有机地球化学等资料，分析了黔东南下寒武统牛蹄塘组、变马冲组页岩孔隙结构与分形特征对储层的影响。下寒武统页岩孔隙结构复杂，分形维数D1，D2的均值分别为2.723和2.867。贫有机质页岩通常具有平板状孔，渗流能力较强，甲烷吸附性较差；富有机质页岩以墨水瓶状和狭缝状孔为主，墨水瓶状孔虽利于油气的滞留与富集，但渗流能力较差，狭缝状孔则兼具较强的渗透性与甲烷吸附性。孔隙结构主要受控于总有机碳质量分数TOC与矿物组分质量分数，随TOC的增加，孔隙结构趋于复杂。当TOC＞4.0%时，D2增幅有限，孔隙结构趋于稳定。

Using the data of low-pressure nitrogen adsorption, mineralogy, organic geochemistry, pore structure and fractal characteristics of Niutitang Formation and Bianmachong Formation of the Lower Cambrian black shales in the Southeast Guizhou area and their influence on reservoir quality were analyzed. The fractal dimensions D1 and D2 with average values of 2.723 and 2.867 indicate extremely complex pore structures. Organic-lean shale commonly has plate-like pores with the features of strong permeability and poor methane sorption; while organic-rich shale often has slit-like and ink bottle pores, the ink bottle pores have poor permeability but facilitate the retention and enrichment of oil and gas. Slit-like pores have both good permeability and methane sorption ability. The pore structure parameters are mainly controlled by the TOC and mineral contents. With the increase of TOC, the pore structure tends to be complex. When the TOC is greater than 4.0%, the increase of D2 is limited, and the pore structure tends to be homogenized and stable.

10.6056/dkyqt201805009