中国南方海相高演化富有机质页岩有机孔保存机理研究

Pore space for the high-maturity marine organic-rich shales in the South China is dominated by organic matter pores. The development of organic matter pores display distinctly differences for the different types of organic-rich, different formations and different areas, which have important relationships with the preservation conditions of organic matter pores. In this project, we focus on the marine organic-rich shales in Niutitang and Wufeng-Longmaxi formations for the typical areas in the south China. The research methods and technologies of mineralogy, geochemistry, geofluids as well as physical simulation experiments are used to study the relationship between the organic matter pores preservation and evolution of pore fluid pressure, supporting capability from the framework minerals grain, organic matter shape and hydrocarbons expulsion efficiencies. The purpose of this project is to reveal the mechanisms for the organic matter pores preservation, confirm the main factors to control the organic matter pores preservation and explain the difference of organic matter pores development in the organic-rich shales with different geology conditions. The research results can provide scientific evidence to reveal the mechanisms for shale gas enrichment and assessment of shale gas exploration potentials of the marine shales in the south China.

我国南方海相高演化富有机质页岩以发育有机孔为主，不同地区、不同层位、不同类型页岩有机孔发育程度的差异性与有机孔保存条件具有重要关系。本研究以我国南方典型地区牛蹄塘组和五峰—龙马溪组海相富有机质页岩为研究对象，在确定页岩孔隙度和孔隙结构、有机孔和无机孔的相对贡献以及有机孔发育特征的基础之上，运用矿物学、地球化学、地质流体的研究思路和技术结合物理模拟实验综合分析孔隙流体压力演化、刚性矿物颗粒支撑、有机质形态以及页岩排烃效率与有机孔保存之间的关系，揭示富有机质页岩有机孔保存机理，明确不同类型页岩有机孔保存的主要控制因素，阐明不同地质条件下富有机质页岩有机孔发育差异性形成原因。该研究成果可为揭示我国南方海相页岩气富集机理和页岩气勘探潜力评价提供科学依据。

中国南方海相高演化富有机质页岩以发育有机孔为主，不同含气性页岩有机孔发育的差异性与有机孔保存条件密切。本研究以我国南方典型地区牛蹄塘组和五峰—龙马溪组页岩为研究对象，在确定富有机质页岩有机孔和无机孔的相对贡献的基础之上，从孔隙流体压力演化、刚性矿物颗粒支撑、有机质形态以及页岩排烃效率与有机孔保存之间的关系，揭示富有机质页岩有机孔保存机理。研究结果表明中国南方海相富有机质页岩主要发育孔径小于15nm的有机微孔和介孔，不同保存条件的页岩有机孔形状存在一定的差异。有机孔体积占总孔隙体积的49%～77%，有机孔比表面积占总孔隙比表面积的50%～84%，有机孔隙为富有机质页岩甲烷吸附和有利区提供主要的储存空间。不同含气性地区的页岩断层和裂缝、储层流体演化以及古压力是控制页岩有机孔保存与页岩气富集的关键因素。该研究成果对认识我国南方海相页岩气富集机理和页岩气勘探潜力评价提供科学依据。