Abstract: Micro pore structure of tight oil reservoir holds the key to research of tight oil reservoir. It is also a main headache for tight oil exploration and development. Micro pore structure of tight oil reservoir is difficult for description of characteristics, classification and appraisal as well as forecast. In addition, pore structure is in complicated relations to oil and gas absorption and filtration. Some progress has been made in overseas study of micro pore structure of tight oil reservoir. For example, nano-pore throats have been discovered and the follow-up study was made on their genesis, thus developing a series of methods for micro-structure analysis and inspection. The digital-core technology was developed to quantitatively analyze components of minerals and their functions in micro flow, effectively clarify and characterize micro fractures, and make comparison and analysis of the sizes of various pores and fluidic molecules in the reservoir. Based on the foreign experience, this article discusses the mindset and method for study of micro pore structure of tight oil reservoir in Ordos Basin, aiming to make breakthrough in testing micro pore structure of tight oil reservoir, confirm existence of nano-pores in tight oil reservoir and its contribution, unveil the matching relations of pores and throats in tight oil reservoir, understand development of micro fracture in tight oil reservoir and its distribution law, and explore the methods for transformation and protection of tight oil reservoir.

Key words: Ordos Basin; tight oil; pore structure; nano-pores; digital core

摘要： 致密油储层微观孔隙结构是致密油储层研究的重点和难点,也是制约致密油勘探、开发的关键问题,主要表现在:致密油储层微观孔隙结构表征难、分类评价难、预测难,并且孔隙结构与油气赋存和渗流的关系复杂等。国外在致密油储层微观孔隙结构研究方面取得了一些进展:发现了纳米孔喉储集类型并研究了其成因;逐级深入,形成了微观尺度分析测试系列方法;发展了数字岩心技术;定量分析了矿物成分及其在微观渗流中的作用;有效识别和表征了微裂缝;对比分析了储层中各类孔隙及流体分子的尺度。根据国外的经验,探讨了鄂尔多斯盆地致密油储层微观孔隙结构研究的思路和方法,指出要在致密油储层微观孔隙结构测试手段上有所突破;要证实致密油储层中纳米级孔隙的存在与否及其贡献;要揭示致密油储层中孔隙和喉道的配置关系;要认识致密油储层中微裂缝发育及分布规律;要探讨致密油储层改造及储层保护的手段。

关键词: 鄂尔多斯盆地, 致密油, 孔隙结构, 纳米孔隙, 数字岩心