Publication Date:
2018
Description:
〈p〉Publication date: February 2019〈/p〉
〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 173〈/p〉
〈p〉Author(s): Boyuan Li, Xiongqi Pang, Yuexia Dong, Junwen Peng, Ping Gao, Hao Wu, Chuang Huang, Xinhe Shao〈/p〉
〈div xml:lang="en"〉
〈h5〉Abstract〈/h5〉
〈div〉〈p〉Shale oil has gradually become the predominant target for unconventional hydrocarbon exploration in recent years. Unlike marine shales that have been extensively studied, lacustrine shales are not adequately characterized in the literature. In this study, we examined Shahejie Formation shales in the Nanpu Sag in the Bohai Bay Basin of China, and performed organic geochemistry, mineralogy, scanning electron microscopy (SEM), and N〈sub〉2〈/sub〉 and CO〈sub〉2〈/sub〉 gas adsorption analyses. The results show that the Shahejie shale can be divided into four lithofacies: siliceous shale, calcareous shale, argillaceous shale, and mixed shale. Calcareous shale was deposited in deep lacustrine environment, and usually has the highest total organic carbon (TOC) content with type I kerogen. Mixed shale, which was deposited in the transitional zone, has moderate TOC values. Argillaceous shale and siliceous shale were deposited in shallow lacustrine environment or near shore, and always have the lowest TOC values. Inorganic mineral pores are the dominant type of pore in all four shale groups. Argillaceous shale has a large amount of intraparticle pores with low average pore size and poor connectivity compared with calcareous shale. Limited organic matter pores are present in low matured lacustrine shales, whereas the porosity of some lacustrine shales may increase due to the occurrence of large number of organic pores leading to significant increase of total porosity. Micro-fissures within calcareous shale greatly improve reservoir quality. Overall, siliceous shale and argillaceous shale usually have low TOC, low residual hydrocarbon, relatively strong adsorption capacity, and poor connectivity of pores, which contain little free oil and are unfavorable for shale oil exploration. Calcareous shale has high TOC, high residual hydrocarbon, large pore size, and excellent fracturing nature, and should be the best target for lacustrine shale oil exploration.〈/p〉〈/div〉
〈/div〉
Print ISSN:
0920-4105
Electronic ISSN:
1873-4715
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Process Engineering, Biotechnology, Nutrition Technology
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