Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment

Topic Information

Dear Colleague,

In recent years, the success of shale oil and gas production in North America has not only cemented the United States’ position as a leader in the global energy landscape but also driven significant advances in geological theory and the development of technologies for shale resources. In China, Cambrian–Ordovician–Silurian marine shales—characterized by high total organic carbon (TOC) and extensive pore–fracture networks—have been used in commercial-scale production. Meanwhile, in Asia, countries such as India, Saudi Arabia, and Pakistan are rapidly advancing unconventional hydrocarbon exploration and pilot projects. This topic brings together the latest insights into the geological mechanisms and technological innovations underpinning shale oil and gas—such as multi-scale pore–fracture characterization, integrated sedimentary–structural–diagenetic modeling, and AI-driven sweet-spot prediction and production optimization—while also incorporating economic evaluation and environmental sustainability to promote efficient, safe, and low-carbon unconventional hydrocarbon development. This topic invites the submission of original research and review articles that integrate geological mechanisms, engineering technologies, and economic–environmental sustainability assessments into a unified, interdisciplinary framework. Themes of interest include, but are not limited to, the following: Global resource appraisal and development management; Fault–fracture networks and their impact on reservoir continuity and productivity; Organic matter enrichment processes and diagenetic evolution; Stratigraphic architecture and facies characterization; Multi-scale pore–fracture network quantification; CO₂-enhanced oil recovery (EOR) and carbon capture, utilization, and storage (CCUS) strategies in unconventional plays; Full life-cycle economic cost–benefit analysis and low-carbon pathway assessment; Hydraulic fracturing design and real-time monitoring; Digital oilfield technologies and closed-loop production control; Environmental, social, and governance (ESG) performance evaluation frameworks; Dependence on mineral resource extraction and challenges in the green-energy transition.

Dr. Hu Li
Dr. Kun Zhang
Topic Editors

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Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.2	7.3	2008	16.8 Days	CHF 2600	Submit
Geosciences geosciences	2.1	5.1	2011	23.6 Days	CHF 1800	Submit
Processes processes	2.8	5.5	2013	14.9 Days	CHF 2400	Submit
Sustainability sustainability	3.3	7.7	2009	17.9 Days	CHF 2400	Submit

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Published Papers (7 papers)

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14 pages, 16451 KB  

Open AccessArticle

Study on Flow Mechanisms in Shale Oil Horizontal Wells Using Fiber-Optic DTS Production Logging

by Hong Zhuo, Si Li, Shaohua Li, Zhangying Han, Xiuling He, Guishan Li and Jianwei Ren

Geosciences 2026, 16(5), 194; https://doi.org/10.3390/geosciences16050194 - 12 May 2026

Abstract

In response to the challenges in monitoring the production profile during the development of the Qingcheng shale oil field in the Changqing Oilfield, this study systematically investigates the application mechanism and practical effectiveness of Distributed Temperature Sensing (DTS) technology for dynamic monitoring in [...] Read more.

In response to the challenges in monitoring the production profile during the development of the Qingcheng shale oil field in the Changqing Oilfield, this study systematically investigates the application mechanism and practical effectiveness of Distributed Temperature Sensing (DTS) technology for dynamic monitoring in horizontal wells. By establishing a coupled model of fracture–matrix dual-porosity media flow and wellbore thermodynamics, which integrates mass, momentum, and energy conservation equations solved via the finite difference method, an interpretation method for the production profile based on the Joule–Thomson effect is proposed. The model was calibrated using shut-in temperature data and validated by comparing simulated temperature profiles with DTS measurements under constant-rate production. Field tests conducted in six horizontal wells in the Qingcheng oil field enabled the quantitative analysis of cluster-level production contributions along the horizontal section, with a water-producing zone localization accuracy of ±3.5 m. The results indicate that shale oil wells exhibit a non-uniform production characteristic of “high at the front and low at the rear” during the early production stage, where the production contribution from fully fractured segments can be up to 2.8 times that of adjacent segments. Inversion of the fiber-optic monitoring data reveals that differences in the conductivity of hydraulic fractures are the primary cause of flow heterogeneity. This research provides a theoretical foundation and technical support for the efficient development of shale oil, contributing to the transition of China’s continental shale oil development from “experience-driven” to “data-driven.” Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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18 pages, 5653 KB  

Open AccessArticle

Evaluation of Geo-Engineering Sweet Spots in Deep Shale Gas Reservoirs of the Northern Luzhou Block

by Shaojun Liu, Xuefeng Yang, Shengxian Zhao, Hao Xu, Yue Lei, Yongyang Liu, Lieyan Cao, Bo Li, Yuanhan He, Ziqiang Xia and Meixuan Yin

Processes 2026, 14(4), 594; https://doi.org/10.3390/pr14040594 - 9 Feb 2026

Viewed by 398

Abstract

The deep formations (burial depth: 3500–4000 m) in the northern Luzhou Block boast favorable geological conditions for shale gas accumulation. However, field development is hindered by the frequent casing deformation of shale gas wells and significant variations in single-well productivity. These issues severely [...] Read more.

The deep formations (burial depth: 3500–4000 m) in the northern Luzhou Block boast favorable geological conditions for shale gas accumulation. However, field development is hindered by the frequent casing deformation of shale gas wells and significant variations in single-well productivity. These issues severely restrict the efficient development of shale gas resources. Existing studies mainly focus on the identification and optimization of geo-engineering dual sweet spots, but few have established a systematic and comprehensive evaluation system from the perspective of engineering risk prevention and control. Based on traditional research on geo-engineering dual sweet spots, this study integrates engineering risk factors. It innovatively establishes a geo-engineering dual sweet spot evaluation system that incorporates engineering risks. Four key evaluation indicators for shale matrix geo-engineering sweet spots are selected: the continuous thickness of a Class I reservoir, the structural location, the fault scale, and natural fracture characteristics. Accordingly, shale matrix geo-engineering sweet spots are classified into three categories: Class I-A Area, Class I-B Area, and Class II Area. Meanwhile, three key indicators affecting fault slip—the angle between fractures and the maximum horizontal in situ stress direction, fracture dip angle, and friction coefficient—are optimized to establish the fault slip risk evaluation criteria. Combined with the distribution characteristics of slip faults, the engineering risks are divided into three levels: high, medium, and low. Finally, by coupling the geo-engineering sweet spots of a shale matrix with engineering risk zones, the geo-engineering sweet spots of shale reservoirs in the study area are classified into four categories (I, II, III, IV). Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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24 pages, 543 KB  

Open AccessArticle

Digital Siphoning and Resource Lock-In: The Distortion and Spatial Divergence of the Digital Economy’s Green Effects

by Xiaodan Gao, Yinhui Wang and Hu Li

Sustainability 2026, 18(2), 1136; https://doi.org/10.3390/su18021136 - 22 Jan 2026

Viewed by 477

Abstract

As digital technologies increasingly permeate urban governance and economic systems, the digital economy (DE) is widely regarded as a key driver of green urban transformation. However, its environmental effects remain complex under the dual constraints of resource dependence (RD) and spatial structure. Drawing [...] Read more.

As digital technologies increasingly permeate urban governance and economic systems, the digital economy (DE) is widely regarded as a key driver of green urban transformation. However, its environmental effects remain complex under the dual constraints of resource dependence (RD) and spatial structure. Drawing on panel data from 277 Chinese prefecture-level cities from 2011 to 2019, this study systematically evaluates the green impacts of the DE across varying resource conditions and urban lifecycle stages. The results reveal a dual-effect pattern: while digitalization significantly promotes local green sustainable development (GSD), it simultaneously suppresses the green performance of neighboring cities through siphoning effects, creating spatial divergence. Cities with lower levels of RD are more likely to benefit from digital dividends, whereas in high-dependence settings, the green effects of digitalization reverse beyond a critical threshold. Grouped regressions for resource-based (RBCs) and non-resource-based cities (NRBCs) further confirm this moderating mechanism. Moreover, lifecycle heterogeneity among RBCs leads to differentiated green outcomes. By introducing the dual mechanisms of “resource lock-in” and “digital siphoning” into the framework of GSD, this study expands the theoretical understanding of the interaction between digitalization and RD. The findings provide empirical support for interpreting the structural divergence in DE–GSD linkages and offer a quantitative basis for differentiated policy strategies in resource-intensive urban contexts. Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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28 pages, 21767 KB  

Open AccessArticle

Reservoir Characteristics and Productivity Controlling Factors of the Wufeng–Longmaxi Formations in the Lu203–Yang101 Well Block, Southern Sichuan Basin, China

by Zhi Gao, Tian Tang, Cheng Yang, Jing Li, Yijia Wu, Ying Wang, Jingru Ruan, Yi Xiao, Hu Li and Kun Zhang

Energies 2026, 19(2), 444; https://doi.org/10.3390/en19020444 - 16 Jan 2026

Viewed by 397

Abstract

The Wufeng–Longmaxi (WF–LMX) shale gas reservoirs at depths > 3500 m in the Lu203–Yang101 well block, southern Sichuan Basin, possess great exploration potential, but their reservoir characteristics and high-production mechanisms remain unclear. In this study, we employed multi-scale analyses—including core geochemistry, X-ray diffraction [...] Read more.

The Wufeng–Longmaxi (WF–LMX) shale gas reservoirs at depths > 3500 m in the Lu203–Yang101 well block, southern Sichuan Basin, possess great exploration potential, but their reservoir characteristics and high-production mechanisms remain unclear. In this study, we employed multi-scale analyses—including core geochemistry, X-ray diffraction (XRD), scanning electron microscopy (SEM), low-pressure N₂ adsorption, and nuclear magnetic resonance (NMR)—to characterize the macro- and micro-scale characteristics of these deep shales. By comparing with shallower shales in adjacent areas, we investigated differences in pore structure between deep and shallow shales and the main controlling factors for high gas-well productivity. The results show that the Long 11 sub-member shales are rich in organic matter, with total organic carbon (TOC) content decreasing upward. The mineral composition is dominated by quartz (averaging ~51%), which slightly decreases upward, while clay content increases upward. Porosity ranges from 1% to 7%; the Long11-1-3 sublayers average 4–6%, locally >6%. Gas content correlates closely with TOC and porosity, highest in the Long11-1 sublayer (6–10 m³/t) and decreasing upward, and the central part of the study area has higher gas content than adjacent areas. The micro-pore structure exhibits pronounced stratigraphic differences: the WF Formation top and Long11-1 and Long11-3 sublayers are dominated by connected round or bubble-like organic pores (50–100 nm), whereas the Long11-2 and Long11-4 sublayers contain mainly smaller isolated organic pores (5–50 nm). Compared to shallow shales nearby, the deep shales have a slightly lower proportion of organic pores, smaller pore sizes with more isolated pores, inorganic pores of mainly intraparticle types, and more developed microfractures, confirming that greater burial depth leads to a more complex pore structure. Type I high-quality reservoirs are primarily distributed from the top of the WF Formation to the Long11-3 sublayer, with a thickness of 15.6–38.5 m and a continuous thickness of 13–23 m. The Lu206–Yang101 area has the thickest high-quality reservoir, with a cumulative thickness of Type I + II exceeding 60 m. Shale gas-well high productivity is jointly controlled by multiple factors: an oxygen-depleted, stagnant deep-shelf environment, with deposited organic-rich, biogenic siliceous shales providing the material basis for high yields; abnormally high pore-fluid pressure with preserved abundant large organic pores and increased free gas content; and effective multi-stage massive fracturing connecting a greater reservoir volume, which is the key to achieving high gas-well production. This study provides a scientific basis for evaluating deep marine shale gas reservoirs in southern Sichuan and understanding the enrichment patterns for high productivity. Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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25 pages, 7223 KB  

Open AccessArticle

Depositional Environment as Main Controlling Factor for Low TOC Sediments in the Early Carboniferous Dawuba Formation of the Qiannan Depression

by Yuzuo Liu, Jiao Wang, Tuo Lin, Dongxiao Li, Jie Chen, Shengzhu Wang, Wanzhong Shi, Ren Wang, Xiaoming Zhang, Xiaofeng Xu and Kai Liu

Geosciences 2025, 15(12), 442; https://doi.org/10.3390/geosciences15120442 - 21 Nov 2025

Cited by 1 | Viewed by 713

Abstract

The evolution of the sedimentary environment in the Early Carboniferous Dawuba Formation of the Qiannan Depression significantly controlled the distribution of low-total organic carbon (TOC) sediments. In this study, the core samples were analyzed by thin section microscopy, field emission-scanning electron microscopy, pyrite [...] Read more.

The evolution of the sedimentary environment in the Early Carboniferous Dawuba Formation of the Qiannan Depression significantly controlled the distribution of low-total organic carbon (TOC) sediments. In this study, the core samples were analyzed by thin section microscopy, field emission-scanning electron microscopy, pyrite morphology, X-ray diffraction, and geochemical analysis (TOC, sulfur, organic petrography, and major and trace elements). The formation is vertically divided into two members from bottom to top: Member 1 (average TOC = 1.15%) and Member 2 (average TOC = 0.88%). Depositional environment parameters indicate that Member 1 was in a suboxic-oxic transition environment, with weak detrital influx, and moderate paleoproductivity (more developed algae). Member 2 evolved into a stable oxic environment, with significantly enhanced detrital influx and reduced paleoproductivity. The correlations between multiple geochemical proxies (paleoredox, paleoproductivity, and terrestrial detrital influx) and TOC content indicate that high productivity in Member 1 was the main driver of organic matter accumulation, but the suboxic-oxic environment limited preservation efficiency (1.00% < TOC < 2.00%). Member 2, deposited during sea-level fall, experienced long-term oxic conditions and low productivity due to shallower water. Nevertheless, the partial reduction in the exposure time of organic matter within the oxic water column-driven by rapid detrital accumulation-represents a critical mechanism favoring organic-poor sediments (TOC < 1.00%). In conclusion, the development of low-TOC sediments in the Dawuba Formation reflects a transition from a relatively deep to shallow water column, where the synergistic effects of redox conditions, paleoproductivity, and terrigenous detrital influx controlled the distribution and enrichment of organic matter. Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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30 pages, 20231 KB  

Open AccessArticle

Effect of Sedimentary Environment on Mudrock Lithofacies and Organic Matter Enrichment in a Freshwater Lacustrine Basin: Insight from the Triassic Chang 7 Member in the Ordos Basin, China

by Meizhou Zhang, Xiaomin Zhu, Wenming Ji, Xingyue Lin and Lei Ye

Sustainability 2025, 17(22), 10248; https://doi.org/10.3390/su172210248 - 16 Nov 2025

Cited by 2 | Viewed by 972

Abstract

Gradually replacing fossil fuels with renewable energy constitutes a long-term strategy for achieving sustainable development. In the short term, it is necessary to explore unconventional oil and gas resources to support current economic sustainability and to secure essential time for the energy transition. [...] Read more.

Gradually replacing fossil fuels with renewable energy constitutes a long-term strategy for achieving sustainable development. In the short term, it is necessary to explore unconventional oil and gas resources to support current economic sustainability and to secure essential time for the energy transition. With the continuous growth in global energy demand, unconventional resources such as shale oil and shale gas have become important alternative energy sources. Lacustrine mudrock successions demonstrate significant potential for unconventional oil and gas resources. However, the unclear understanding of how paleoenvironmental evolution influences lithofacies and organic matter enrichment restricts the optimization of shale oil reservoirs and evaluation of shale oil resources, thereby hindering the progress of lacustrine shale oil exploration and development. The mudrocks in the Chang 7 Member of the Triassic Yanchang Formation, Ordos Basin, were deposited in a pro-delta to a deep lacustrine environment and are rich in shale oil resources. Through petrographic, sedimentological, sequence stratigraphic, and geochemical analyses, this study reveals how the evolution of the paleoenvironment controlled the development of mudrocks and the enrichment of organic matter, and establishes a sedimentary model for freshwater lacustrine systems. Six lithofacies have been identified within the mudrock interval of the Chang 7 Member. According to the T-R (transgressive–regressive) sequence model, the Chang 7 Member can be subdivided into three fourth-order sequences, termed Parasequence Set 1–3 (PPS1–3). Mudrock is predominantly developed in the fourth-order sequences PSS1 and PSS2. The PSS1 and the lower part of PSS2 consist of lithofacies 1–4, representing semi-deep to deep lacustrine deposits. The upper part of PSS2 develops lithofacies 5, representing shallow lacustrine to pro-delta deposits. Fluctuations of the lake level controlled the vertical stacking of lithofacies and the transition in depositional mechanisms. During lake-level rise, bottom currents shifted to suspension settling, whereas the opposite occurred during lake-level fall. The organic matter is derived from algae, and its enrichment is jointly controlled by productivity and the redox conditions. Volcanic–hydrothermal activity and a humid climate promoted high productivity in the water body. This high productivity promotes dyoxic conditions in the bottom water. Fourth-order relative lake-level fluctuations also influence organic matter enrichment. During lake-level rise, increased productivity coupled with reduced consumption and dilution favors organic matter enrichment. Conversely, organic matter accumulation is inhibited during lake-level fall. Ultimately, a depositional model for a freshwater lacustrine basin under a humid to semi-humid climatic background was established. This paper elucidates the influence of sedimentary environment on mudrock lithofacies and organic matter enrichment, providing a theoretical basis for optimizing shale oil reservoir selection and resource assessment, thereby promoting efficient exploration and low-carbon development of shale oil in lacustrine basins. Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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16 pages, 2261 KB  

Open AccessArticle

From Shale to Value: Dual Oxidative Route for Kukersite Conversion

by Kristiina Kaldas, Kati Muldma, Aia Simm, Birgit Mets, Tiina Kontson, Estelle Silm, Mariliis Kimm, Villem Ödner Koern, Jaan Mihkel Uustalu and Margus Lopp

Processes 2025, 13(8), 2421; https://doi.org/10.3390/pr13082421 - 30 Jul 2025

Viewed by 990

Abstract

The increasing need for sustainable valorization of fossil-based and waste-derived materials has gained interest in converting complex organic matrices such as kerogen into valuable chemicals. This study explores a two-step oxidative strategy to decompose and valorize kerogen-rich oil shale, aiming to develop a [...] Read more.

The increasing need for sustainable valorization of fossil-based and waste-derived materials has gained interest in converting complex organic matrices such as kerogen into valuable chemicals. This study explores a two-step oxidative strategy to decompose and valorize kerogen-rich oil shale, aiming to develop a locally based source of aliphatic dicarboxylic acids (DCAs). The method combines air oxidation with subsequent nitric acid treatment to enable selective breakdown of the organic structure under milder conditions. Air oxidation was conducted at 165–175 °C using 1% KOH as an alkaline promoter and 40 bar oxygen pressure (or alternatively 185 °C at 30 bar), targeting 30–40% carbon conversion. The resulting material was then subjected to nitric acid oxidation using an 8% HNO₃ solution. This approach yielded up to 23% DCAs, with pre-oxidation allowing a twofold reduction in acid dosage while maintaining efficiency. However, two-step oxidation was still accompanied by substantial degradation of the structure, resulting in elevated CO₂ formation, highlighting the need to balance conversion and carbon retention. The process offers a possible route for transforming solid fossil residues into useful chemical precursors and supports the advancement of regionally sourced, sustainable DCA production from unconventional raw materials. Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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