New insights on the retention and migration of shale oil within the hypersaline Qianjiang Formation in the Jianghan Basin, China

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

AAPG Bulletin Pub Date : 2024-03-01 DOI:10.1306/11022323026

Zhiliang He, Yuanjia Han, Qinglai Luo, Fu Wang, Furong Wang, Shiqiang Wu

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Abstract

Super giants of oil are present in the hypersaline Qianjiang shale of the Jianghan Basin. Although the oil in place of intersalt shale is controlled potentially by the total organic carbon (TOC) content, the extremely high values of the oil saturation index (OSI), ranging from 100 to 600 mg/g TOC, are widely revealed to be a result of lateral charging of self-sourced petroleum from deep sags. However, a comprehensive review of the literature combined with a case study of producing wells leads to new insights into the retention and migration of oil within the hypersaline Qianjiang shale. Except for the lateral migration, vertical oil migration and oil retention within sulfur-rich kerogen in situ are important replenishments, if not key factors, accounting for the enrichment of high-quality petroleum fluids in the Qianjiang shale. Intraformational migration of oil vertically from source rock layers to juxtaposed shale reservoirs is evidenced by (1) anomalously high OSI values of >400 mg/g TOC, (2) negative expulsion efficiency values, and (3) preferential expulsion of saturate hydrocarbons > aromatic hydrocarbons > polar compounds. Notably, the widely used maturity parameters are unsuitable for assessing the sulfur-rich Qianjiang shale play. Therefore, previous findings on the updip oil migration within individual cyclothem units are questionable. We believe that the present concerns regarding oil retention and migration within the hypersaline Qianjiang shale deserve the focus of much debate and suggest their re-examination.

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关于中国江汉盆地潜江超盐地层中页岩油滞留和迁移的新见解

江汉盆地的高盐度潜江页岩中存在超巨型石油。虽然盐间页岩的含油量可能受总有机碳（TOC）含量的控制，但石油饱和度指数（OSI）的极高值（100 至 600 mg/g TOC）被广泛认为是深陷自采石油横向充注的结果。然而，通过对文献的全面梳理和对生产井的案例研究，我们对石油在高盐度黔江页岩中的滞留和迁移有了新的认识。除横向迁移外，石油的垂直迁移和原地富硫角质层内的石油滞留是黔江页岩富含优质石油流体的重要补充，甚至是关键因素。石油从源岩层垂直向并列页岩储层的构造内迁移表现为：（1）异常高的 OSI 值（大于 400 mg/g TOC）；（2）负的排出效率值；（3）优先排出饱和烃 > 芳烃 > 极性化合物。值得注意的是，广泛使用的成熟度参数并不适合评估富含硫磺的黔江页岩区。因此，之前关于单个旋回单元内石油向下迁移的研究结果值得商榷。我们认为，目前有关黔江页岩中石油滞留和迁移的问题值得重点讨论，并建议重新研究。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

AAPG Bulletin 工程技术-地球科学综合

CiteScore

6.60

自引率

11.40%

发文量

审稿时长

4.8 months

期刊介绍： While the 21st-century AAPG Bulletin has undergone some changes since 1917, enlarging to 8 ½ x 11” size to incorporate more material and being published digitally as well as in print, it continues to adhere to the primary purpose of the organization, which is to advance the science of geology especially as it relates to petroleum, natural gas, other subsurface fluids, and mineral resources. Delivered digitally or in print monthly to each AAPG Member as a part of membership dues, the AAPG Bulletin is one of the most respected, peer-reviewed technical journals in existence, with recent issues containing papers focused on such topics as the Middle East, channel detection, China, permeability, subseismic fault prediction, the U.S., and Africa.