Earth Science Frontiers ›› 2025, Vol. 32 ›› Issue (6): 350-366.DOI: 10.13745/j.esf.sf.2025.8.67

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Spatio-temporal fractal structures in sedimentary sequences and their geological significance

RUAN Zhuang1(), WANG Yueyun2, CHANG Qiuhong1, YU Bingsong1,*()   

  1. 1. School of Geosciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. Exploration and Development Research Institute, PetroChina Southwest Oil & Gasfield Company, Chengdu, 610041, China
  • Received:2025-05-20 Revised:2025-06-13 Online:2025-11-25 Published:2025-11-12
  • Contact: YU Bingsong

Abstract:

The formation of sedimentary sequences is controlled by tectonic activity, sea (lake)-level change, and climate evolution, resulting in complex multiscale spatiotemporal structures. While traditional methods struggle to reveal their intrinsic patterns, fractal theory offers a novel approach. Using the Shahejie Formation in the Jiyang Depression as a case study, this research systematically analyzes the spatiotemporal fractal structures of sedimentary sequences and their geological implications. First, the Hurst index quantifies temporal fractal characteristics to interpret sedimentary environment evolution. Second, power spectral density analysis reveals self-organized criticality (SOC) of the sedimentary system, and a filter-based technique for extracting long-range spatiotemporal correlations is proposed. Finally, fractal dimensions of pore structures are characterized to quantitatively evaluate their impact on reservoir permeability. Results demonstrate that: (1) The Hurst index quantifies long-term sedimentary trends; (2) SOC optimizes reservoir parameter analysis; (3) Fractal theory critically supports pore-throat structure evaluation. This study advances understanding of sedimentary complexity and provides new theoretical/methodological foundations for hydrocarbon exploration and reservoir assessment.

Key words: fractal theory, spatio-temporal fractal structure, Hurst index, power spectrum analysis, pore throat structure evaluation

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