Abstract:

With the development of technology and research, more and more scholars have realized that the study of shale oil reservoir characteristics is very important for the selection of “sweet spots/segments”. By studying the “four characteristics” of the shale oil reservoir in the Second Member of Funing Formation, Subei basin, such as oil content, reservoir property, mobility， and compressibility, the reservoir space characteristics are described in detail, and the main controlling factors affecting the reservoir property are analyzed, which provides strong support for further exploration and evaluation and large-scale development in this area. The results show that the Second Member of Funing Formation mainly develops laminated or layered shale, and its mineral composition is clay minerals (35.4% on average), felsic minerals (39.1% on average), and carbonate minerals (19.8% on average), w(TOC) is 0.5%-2.0%, Ro is 0.9%-1.1%, and porosity is 1.8%-5.2%. The lamellar structure is the most prominent fabric feature of the shale in the Second Member of Funing Formation, which is mainly composed of felsic and clay lamination. According to the characteristics of “abundant organic matter + structural characteristics + lithology”, the shale of the Second Member of Funing Formation can be divided into 6 lithofacies. According to the comprehensive evaluation of “four characteristics”, the medium organic laminated/layered shales are the favorable lithofacies. The main reservoir space types are bedding seams, structural seams, intergranular pores, and clay mineral intercrystalline pores. However, the reservoir space types differ among lithofacies, mainly affected by lithology, mineral composition, and the degree of lamination development, as well as minor structural effects. Comprehensively analyzing the “four properties” of the six lithofacies of the Funing Formation, the middle and lower parts of the organic-rich laminated/layered shale are the geological sweet spots for shale oil exploration and development.

Key words: Subei basin')">

Subei basin, Qintong depression, Funing Formation, shale oil, storage space, influence factor, oil and gas