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ORIGINAL RESEARCH article

Front. Earth Sci.
Sec. Solid Earth Geophysics
Volume 13 - 2025 | doi: 10.3389/feart.2025.1537217
This article is part of the Research Topic Advances in Petrophysics of Unconventional Oil and Gas View all articles

Three-dimensional Reconstruction and Connectivity Analysis of REV-size Organic Matter in Shales

Provisionally accepted
Dongchen Liu Dongchen Liu 1,2Xuefeng Yang Xuefeng Yang 1Shengxian Zhao Shengxian Zhao 1Deliang Zhang Deliang Zhang 1Shan Huang Shan Huang 1Ning Zhu Ning Zhu 1Jianqi Rong Jianqi Rong 3,4Bowen Shi Bowen Shi 3,4Zhiwei Wang Zhiwei Wang 3,4*Chao-Zhong Qin Chao-Zhong Qin 3,4*
  • 1 PetroChina Southwest Oil and Gasfield Company, Chengdu, Sichuan Province, China
  • 2 State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu, Sichuan Province, China
  • 3 State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China
  • 4 School of Resources and Safety Engineering, Chongqing University, Chongqing, China

The final, formatted version of the article will be published soon.

    Organic matter (OM) serves as a crucial site for shale gas generation and occurrence. Its content and spatial connectivity significantly influence gas flow ability and gas occurrence. However, in characterizing the three-dimensional (3D) connectivity of OM, current imaging techniques such as FIB-SEM and nano-CT cannot balance field of view (FoV) and image resolution. To address this gap, in this work, we develop a novel workflow for numerical reconstruction of REV-size digital rocks of OM that integrates high-resolution information of pore structures in large-view MAPS (modular automated processing system) images. Specifically, the open source code, SliceGAN, is used in the 3D reconstruction of digital rocks of OM, while the high-resolution information of OM pore structures is integrated into the digital rocks in terms of the classification of OM in the MAPS images. The classification of OM is solely based on the surface or 2D porosity of individual OM watersheds. As a first attempt, we propose three types of OM including Type A with high porosity (>20%), Type B with medium porosity (10%~20%), and Type C with low porosity (<10%). Based on the case studies of three in-situ shale samples with different OM contents, we show that at the REV size the three types of OM, as a whole, can form conducting pathways throughout the domains, but each type of OM is disconnected. Type A and Type B OM have poor connectivity, while Type C OM holds the best connectivity dominating gas transport at the REV scale. Moreover, the reconstructed 3D digital rocks of OM can be used in the numerical modeling of REV-size gas transport in shales.

    Keywords: ：organic matter, MAPS images, REV size, connectivity, 3D reconstruction of digital rocks

    Received: 30 Nov 2024; Accepted: 09 Jan 2025.

    Copyright: © 2025 Liu, Yang, Zhao, Zhang, Huang, Zhu, Rong, Shi, Wang and Qin. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Zhiwei Wang, State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China
    Chao-Zhong Qin, State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.