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Sustainable Development of Unconventional Geo-Energy

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "H: Geo-Energy".

Deadline for manuscript submissions: 20 October 2025 | Viewed by 881

Special Issue Editor


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Guest Editor
College of Resources and Civil Engineering, Northeastern University, Shenyang 110167, China
Interests: theory and application of sedimentology; petroleum geology; integration of unconventional petroleum geology and engineering

Special Issue Information

Dear Colleagues,

This Special Issue aims to bring together cutting-edge research achievements from multiple disciplinary perspectives, deeply explore the complex issues of unconventional energy in resource exploration, development technology, environmental impact, etc., and provide theoretical support and practical guidance for promoting the sustainable utilization of unconventional energy. In terms of resource exploration, with the continuous advancement of technology, the reserve assessment of unconventional energy sources such as shale gas, coalbed methane, oil shale, and deep-sea oil and gas has become increasingly accurate. However, how to achieve efficient and economical exploration under complex geological conditions remains an urgent problem to be solved. The innovation of development technologies is the key to increasing the output of unconventional energy sources, including the optimization of technologies such as horizontal drilling and hydraulic fracturing, as well as the research and development of new extraction technologies, such as microbial oil recovery and carbon dioxide flooding. These technologies, while enhancing the recovery rate, also need to take into account the impact on the ecological environment. Environmental impact assessment is an important indicator for measuring the sustainability of unconventional energy. From water consumption and the destruction of surface vegetation to greenhouse gas emissions, comprehensively and accurately quantifying these impacts and exploring effective environmental restoration and emission reduction strategies are inevitable requirements for achieving the green development of unconventional energy.

We sincerely invite researchers from multiple disciplines such as energy science, environmental science, economics, and policy studies to actively contribute their latest research achievements, innovative viewpoints, practical experiences, and case analyses. Let us work together to contribute wisdom and strength to the sustainable development of unconventional energy and jointly usher in a new era of unconventional energy development.

Dr. Yuying Zhang
Guest Editor

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Keywords

  • resource exploration
  • reservoir characteristics
  • drilling and completion
  • fracturing technology
  • enhanced oil recovery
  • optimization of the development program
  • safe life cycle
  • environmental impact assessment
  • green development technology
  • economic feasibility analysis
  • policy support and supervision
  • big data and AI applications
  • intelligent oil and gas fields
  • multidisciplinary integration

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Published Papers (2 papers)

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Research

20 pages, 6495 KiB  
Article
Fractal Characterization of Pore Structures in Marine–Continental Transitional Shale Gas Reservoirs: A Case Study of the Shanxi Formation in the Ordos Basin
by Jiao Zhang, Wei Dang, Qin Zhang, Xiaofeng Wang, Guichao Du, Changan Shan, Yunze Lei, Lindong Shangguan, Yankai Xue and Xin Zhang
Energies 2025, 18(15), 4013; https://doi.org/10.3390/en18154013 - 28 Jul 2025
Viewed by 273
Abstract
Marine–continental transitional shale is a promising unconventional gas reservoir, playing an increasingly important role in China’s energy portfolio. However, compared to marine shale, research on marine–continental transitional shale’s fractal characteristics of pore structure and complete pore size distribution remains limited. In this work, [...] Read more.
Marine–continental transitional shale is a promising unconventional gas reservoir, playing an increasingly important role in China’s energy portfolio. However, compared to marine shale, research on marine–continental transitional shale’s fractal characteristics of pore structure and complete pore size distribution remains limited. In this work, high-pressure mercury intrusion, N2 adsorption, and CO2 adsorption techniques, combined with fractal geometry modeling, were employed to characterize the pore structure of the Shanxi Formation marine–continental transitional shale. The shale exhibits generally high TOC content and abundant clay minerals, indicating strong hydrocarbon-generation potential. The pore size distribution is multi-modal: micropores and mesopores dominate, contributing the majority of the specific surface area and pore volume, whereas macropores display a single-peak distribution. Fractal analysis reveals that micropores have high fractal dimensions and structural regularity, mesopores exhibit dual-fractal characteristics, and macropores show large variations in fractal dimension. Characteristics of pore structure is primarily controlled by TOC content and mineral composition. These findings provide a quantitative basis for evaluating shale reservoir quality, understanding gas storage mechanisms, and optimizing strategies for sustainable of oil and gas development in marine–continental transitional shales. Full article
(This article belongs to the Special Issue Sustainable Development of Unconventional Geo-Energy)
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26 pages, 9458 KiB  
Article
Wettability Characteristics of Mixed Sedimentary Shale Reservoirs in Saline Lacustrine Basins and Their Impacts on Shale Oil Energy Replenishment: Insights from Alternating Imbibition Experiments
by Lei Bai, Shenglai Yang, Dianshi Xiao, Hongyu Wang, Jian Wang, Jin Liu and Zhuo Li
Energies 2025, 18(14), 3887; https://doi.org/10.3390/en18143887 - 21 Jul 2025
Viewed by 301
Abstract
Due to the complex mineral composition, low clay content, and strong heterogeneity of the mixed sedimentary shale in the Xinjiang Salt Lake Basin, the wettability characteristics of the reservoir and their influencing factors are not yet clear, which restricts the evaluation of oil-bearing [...] Read more.
Due to the complex mineral composition, low clay content, and strong heterogeneity of the mixed sedimentary shale in the Xinjiang Salt Lake Basin, the wettability characteristics of the reservoir and their influencing factors are not yet clear, which restricts the evaluation of oil-bearing properties and the identification of sweet spots. This paper analyzed mixed sedimentary shale samples from the Lucaogou Formation of the Jimsar Sag and the Fengcheng Formation of the Mahu Sag. Methods such as petrographic thin sections, X-ray diffraction, organic matter content analysis, and argon ion polishing scanning electron microscopy were used to examine the lithological and mineralogical characteristics, geochemical characteristics, and pore space characteristics of the mixed sedimentary shale reservoir. Alternating imbibition and nuclear magnetic resonance were employed to quantitatively characterize the wettability of the reservoir and to discuss the effects of compositional factors, lamina types, and pore structure on wettability. Research findings indicate that the total porosity, measured by the alternate imbibition method, reached 72% of the core porosity volume, confirming the effectiveness of alternate imbibition in filling open pores. The Lucaogou Formation exhibits moderate to strong oil-wet wettability, with oil-wet pores predominating and well-developed storage spaces; the Fengcheng Formation has a wide range of wettability, with a higher proportion of mixed-wet pores, strong heterogeneity, and weaker oil-wet properties compared to the Lucaogou Formation. TOC content has a two-segment relationship with wettability, where oil-wet properties increase with TOC content at low TOC levels, while at high TOC levels, the influence of minerals such as carbonates dominates; carbonate content shows an “L” type response to wettability, enhancing oil-wet properties at low levels (<20%), but reducing it due to the continuous weakening effect of minerals when excessive. Lamina types in the Fengcheng Formation significantly affect wettability differentiation, with carbonate-shale laminae dominating oil pores, siliceous laminae contributing to water pores, and carbonate–feldspathic laminae forming mixed pores; the Lucaogou Formation lacks significant laminae, and wettability is controlled by the synergistic effects of minerals, organic matter, and pore structure. Increased porosity strengthens oil-wet properties, with micropores promoting oil adsorption through their high specific surface area, while macropores dominate in terms of storage capacity. Wettability is the result of the synergistic effects of multiple factors, including TOC, minerals, lamina types, and pore structure. Based on the characteristic that oil-wet pores account for up to 74% in shale reservoirs (mixed-wet 12%, water-wet 14%), a wettability-targeted regulation strategy is implemented during actual shale development. Surfactants are used to modify oil-wet pores, while the natural state of water-wet and mixed-wet pores is maintained to avoid interference and preserve spontaneous imbibition advantages. The soaking period is thus compressed from 30 days to 3–5 days, thereby enhancing matrix displacement efficiency. Full article
(This article belongs to the Special Issue Sustainable Development of Unconventional Geo-Energy)
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