Logging identification and prediction of lithofacies of lacustrine shale system in Shichang Sub-Sag, Nanpu Depression

Autor: Bang Zeng, Xiaoping Liu, Guoyong Liu, Shaochun Wang, Guoyong Li
Jazyk: čínština
Rok vydání: 2021
Předmět:
Zdroj: 地质科技通报, Vol 40, Iss 1, Pp 69-79 (2021)
Druh dokumentu: article
ISSN: 2096-8523
DOI: 10.19509/j.cnki.dzkq.2021.0103
Popis: The study of the lithofacies of shale formation is the basic work for shale oil exploration.Due to the limited distribution of the continental lacustrine basin and the fast variations of lithofacies, it is difficult to accurately identify and predict the lithofacies.With high precision and good continuity in vertical direction, the logging curve can be used to accurately identify and predict the lithofacies.Based on the experimental data of whole-rock X-ray diffraction(XRD), thin-section identification and geochemical analysis data, the lithofacies can be divided according to the division scheme named three classes & ternary plots.Fitting logging data with TOC value and mineral content, the lithofacies can be comprehensively identified.Finally, the cycle superposition model of lithofacies is established under the high-resolution sequence frame to study the distribution of lithofacies.The results show that the area is a set of oil-bearing lacustrine source rocks with Ⅰ and Ⅱ1 kerogen, which can be divided into 18 types of lithofacies, among which organic-rich argillaceous lamellar shale and organic-rich mixed lamellar shale are the dominant lithofacies.The evaluation indexes of the lithofacies can be calculated and predicted through the logging curve.There is a coupling relationship between the lithofacies and the sequence so that the lithofacies are predictable under the isochronous stratigraphic framework.The lithofacies of shale formation of the Es34 sub-member are under this framework, forming two organic-rich layers located in the middle of MSC1 and MSC2 middle cycles and four sedimentary tectonic development zones corresponding to the SQ5-SQ8 ascending semi-cycling.
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