波罗的海盆地上奥陶统页岩孔隙演化的热压模拟实验

Thermal-pressure simulation experiment of pore evolution of Upper Ordovician shale in Baltic Basin

李楚雄 申宝剑 潘安阳 张文涛 李昂 丁江辉

LI Chuxiong SHEN Baojian PAN Anyang ZHANG Wentao LI Ang DING Jianghui

中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126 页岩油气富集机理与有效开发国家重点实验室, 江苏 无锡 214126

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China State Key Laboratory of Mechanism and Effective Development of Oil and Gas Enrichment in Shale, Wuxi, Jiangsu 214126, China

我国南方海相页岩大多处于高-过熟演化阶段，无法再现地质历史过程中孔隙的演化过程。选取欧洲地区波罗的海盆地上奥陶统页岩开展了近地质条件的室内热压模拟实验，以期揭示海相页岩孔隙的演化规律和赋存状态。结合实验样品的有机岩石学特征、模拟产物的定量化统计和扫描电镜微区分析，系统阐述了模拟实验页岩孔隙在有机质熟化过程中的演化特征和形成机理。实验条件下，页岩整体孔隙的发育程度随有机质热演化程度的增加而提高，孔隙之间趋于连通，由初始的孔隙不发育状态逐渐演变为复杂交错的孔隙网络。根据孔隙的形态和成因，将有机孔和无机矿物孔细分为8类：海绵状有机孔、有机质收缩孔和气泡状有机孔；铸膜孔、溶蚀孔、矿物粒间孔、黏土矿物层间孔和改造矿物孔。受有机显微组分的差异、有机质的转化和油气初次运移的影响，有机孔的分布表现出较强的非均质性，无机矿物孔的发育呈现出阶段性。孔隙的有效保存问题在高演化阶段页岩气勘探过程中需要重点关注。

Most of the marine shale in South China is highly over mature and the pore evolution history cannot be determined. The Upper Ordovician shale in the Baltic Basin in Europe was selected to conduct a laboratory thermal-pressure simulation experiment to emulate geological conditions in order to reveal the evolution and distribution of marine shale pores. The evolution characteristics and formation mechanism of the experimental shale pores during the maturation of organic matter were systematically explained based on the organic petrological characteristics of the raw shale samples, the quantitative statistics of the simulated products, and the scanning electron microscopy analysis. The development of the overall shale pores increases with the increase of the thermal evolution of organic matter. The pores tend to communicate with each other, and gradually evolve from the initial undeveloped state to a complex and interlaced pore network. Organic and inorganic pores are subdivided into 8 categories according to their morphology and origin: spongy organic matter (OM), shrinkage OM, bubble OM, mold, mineral dissolution, intergranular, clay mineral interlayer and modified mineral pores. The transformation degree of organic matter and the primary migration of oil and gas are influenced by the difference of organic macerals. The distribution of organic matter pores showed a strong heterogeneity, and the development of inorganic mineral pores occurred in stages. The effective preservation of pores needs special attention during the shale gas exploration in the high evolution stage.

国家油气重大专项 2017ZX05036-002;国家自然科学基金面上项目 41972164

https://doi.org/10.11781/sysydz202003434