Advanced Technology in Unconventional Resource Development

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Chemical Processes and Systems".

Deadline for manuscript submissions: 31 December 2025 | Viewed by 2920

Special Issue Editors


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Guest Editor
School of Petroleum Engineering, China University of Petroleum, Beijing 102249, China
Interests: unconventional gas and oil development
Special Issues, Collections and Topics in MDPI journals
College of Petroleum and Natural Gas Engineering, Southwest Petroleum University, Chengdu, China
Interests: enhanced oil recovery (EOR); carbon capture, use and storage (CCUS)
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The development of tight oil reservoirs and other unconventional resources has been attracting increasing attention. Recently, there has been a rising number of works showcasing new and advanced technologies in tight oil research, including seepage law, Interfacial phenomena, production mechanisms, new chemical agent development, and methods to simulate multiphase flow in porous media based on laboratory work and reservoir simulation.

This Special Issue on “Advanced Technology in Unconventional Resource Development” seeks high-quality works focusing on the latest methodological and technological advances in the development of tight oil and other unconventional resources. Topics include, but are not limited to, the following:

  • Advanced methods in characterizing tight oil reservoirs;
  • Multiphase flow in tight oil reservoirs;
  • EOR methods in tight oil reservoir development;
  • Machine learning or big data application in tight oil reservoir development.

Dr. Xiuyu Wang
Dr. Xiao Wang
Guest Editors

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • tight oil reservoir
  • seepage law
  • spontaneous imbibition
  • CO2 flooding
  • chemical flooding

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Published Papers (6 papers)

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Research

16 pages, 2080 KiB  
Article
Quantitative Characterization and Risk Classification of Frac Hit in Deep Shale Gas Wells: A Machine Learning Approach Integrating Geological and Engineering Factors
by Bo Zeng, Yuliang Su, Jianfa Wu, Dengji Tang, Ke Chen, Yi Song, Chen Shen, Yongzhi Huang, Yurou Du and Wenfeng Yu
Processes 2025, 13(6), 1785; https://doi.org/10.3390/pr13061785 - 5 Jun 2025
Viewed by 207
Abstract
With the continued advancement of shale gas development, the issue of frac hit has become increasingly prominent and has emerged as a key factor influencing the production of shale gas wells. Quantitative evaluation of the impact of frac hit on shale gas wells [...] Read more.
With the continued advancement of shale gas development, the issue of frac hit has become increasingly prominent and has emerged as a key factor influencing the production of shale gas wells. Quantitative evaluation of the impact of frac hit on shale gas wells and proposing different methods to prevent frac hit are of great significance for the efficient development of shale gas. This research puts forward a machine learning-based workflow that incorporates geological and engineering factors to evaluate the impacts of frac hit. The “Frac Hit Pressure Integral Index (FPI)” quantifies the dynamic pressure responses by means of the ratios of initial pressure to shut-in pressure. Pearson analysis is employed to reduce the dimensionality of parameters, and Random Forest and K-means++ algorithms are utilized to classify the risks of frac hit. Among numerous influencing factors, it has been found that the brittleness index and well spacing possess the highest weights among the geological and engineering influencing factors, reaching 20.4 and 16.1, respectively. The L well area of southern Sichuan shale gas lies in the Fuji syncline of the Huaying Mountain tectonic system’s low-fold Fujian zone. When applied to the L well area in the Sichuan Basin, the results pinpoint the brittleness index, fluid intensity, and well spacing as crucial factors. It is recommended that, for reservoirs with high fracturability, reducing fluid intensity and increasing well spacing can minimize inter-well interference. This workflow classifies risks into low (FPI ≤ 265.43), medium (265.43 < FPI < 658.56), and high levels (FPI ≥ 658.56) and recalibrates natural fracture zones based on pressure and flowback data, thereby enhancing the alignment between geological and engineering aspects by 10%. This framework optimizes fracturing designs and mitigates inter-well interference, providing support for the efficient development of shale gas. Full article
(This article belongs to the Special Issue Advanced Technology in Unconventional Resource Development)
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22 pages, 1252 KiB  
Article
Probabilistic Modeling and Interpretation of Inaccessible Pore Volume in Polymer Flooding
by Chuanfeng Zhao, Yifan Zhao and Shengyun Zhan
Processes 2025, 13(6), 1720; https://doi.org/10.3390/pr13061720 - 30 May 2025
Viewed by 247
Abstract
Inaccessible pore volume fraction (IPV) significantly affects polymer transport and retention in porous media during enhanced oil recovery. Conventional methods typically estimate IPV using deterministic or empirical models. These approaches often overlook the randomness in pore and polymer size distributions. This study introduces [...] Read more.
Inaccessible pore volume fraction (IPV) significantly affects polymer transport and retention in porous media during enhanced oil recovery. Conventional methods typically estimate IPV using deterministic or empirical models. These approaches often overlook the randomness in pore and polymer size distributions. This study introduces a probabilistic framework that redefines IPV as a stochastic outcome of size exclusion interactions between polymer molecules and pore throats. Ten mathematically equivalent formulations were developed based on the expectation or event probability logic, and from both polymer- and pore-centered perspectives. All models were analytically verified for consistency. Case studies using representative pore and polymer size distributions (0.1–20 μm and 1–5 μm) confirm that the models yield consistent IPV values across formulations. Sensitivity analysis shows that the results respond to the key parameters, such as the exclusion threshold. The results were computed from probability distributions, weighted based on exclusion rules derived from absolute size values. For instance, increasing the exclusion parameter from 3.0 to 5.0 led to a sharp rise in IPV from 0.0367 to 0.3713. Fundamentally, this framework offers a new perspective. It redefines IPVF as a derived probabilistic quantity governed by physically meaningful size distributions, rather than a fixed empirical input. By decoupling estimation from raw size data and emphasizing distribution-driven computation, the method improves robustness and interpretability and enables integration into uncertainty-aware simulators and data-driven workflows. Full article
(This article belongs to the Special Issue Advanced Technology in Unconventional Resource Development)
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12 pages, 2326 KiB  
Article
Study of Specific Problems Arising in the Blending Processes of Crude Oils (Based on the Examples of Azerbaijan Oils)
by Xiuyu Wang, Gafar Ismayilov, Elman Iskandarov, Elnur Alizade and Fidan Ismayilova
Processes 2025, 13(5), 1500; https://doi.org/10.3390/pr13051500 - 13 May 2025
Viewed by 296
Abstract
Experiences in the production, transportation and preparation of crude oil for transportation have shown that specific problems arise related to their mixing, including water contamination. In recent years, interest in studying these problems has significantly increased, mainly due to the development of extraction [...] Read more.
Experiences in the production, transportation and preparation of crude oil for transportation have shown that specific problems arise related to their mixing, including water contamination. In recent years, interest in studying these problems has significantly increased, mainly due to the development of extraction technologies for heavy oil samples and bitumen. Along with various difficulties encountered during the pipeline transportation of complex rheological crude oil blended with each other and with light oil, including condensate (such as sedimentation, etc.), imbalances are also observed during storage, as well as in the processes of delivery and reception. During the dehydration of oil mixtures, a synergistic effect is observed in the consumption of demulsifier. The article investigates, in accordance with international standards and based on laboratory tests, how the physico-chemical properties (density, viscosity, freezing point, saturated vapor pressure, chemical composition) of mixtures formed by blending various grades and compositions of Azerbaijani oil examples with each other and with condensate change and how the efficiency of dehydration of oil mixtures is affected by the mixing ratio of the oil involved. It was found that the quality indicators (physico-chemical parameters) of oil mixtures differ non-additively from the initial parameters of the blended products and in some cases, this difference is even observed with anomalies. Moreover, depending on the mixing ratio of the oil, variations in the consumption of demulsifier were also identified. Full article
(This article belongs to the Special Issue Advanced Technology in Unconventional Resource Development)
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12 pages, 2765 KiB  
Article
Comparative Analysis of Microscopic Pore Throat Heterogeneity in the Chang 6 Tight Sandstone Reservoir: Implications for Production Dynamics and Development Strategies in the Wuqi-Dingbian Region, Ordos Basin
by Jun Li, Mingwei Wang, Yan Li, Kaitao Yuan, Liang Liu and Lingdong Meng
Processes 2025, 13(4), 1109; https://doi.org/10.3390/pr13041109 - 7 Apr 2025
Viewed by 218
Abstract
This study systematically investigates the heterogeneity of the Chang 6 reservoir in the Wuqi–Dingbian region of the Ordos Basin through integrated petrographic analysis using scanning electron microscopy (SEM), thin-section petrography, and mercury intrusion porosimetry. The results reveal that this feldspathic sandstone reservoir exhibits [...] Read more.
This study systematically investigates the heterogeneity of the Chang 6 reservoir in the Wuqi–Dingbian region of the Ordos Basin through integrated petrographic analysis using scanning electron microscopy (SEM), thin-section petrography, and mercury intrusion porosimetry. The results reveal that this feldspathic sandstone reservoir exhibits significant compositional and textural variations controlled by depositional environments. Dingbian samples displayed elevated feldspar (avg. 42.3%), lithic fragments (18.1%), and carbonate cementation (15.7%), accompanied by intense mechanical compaction and cementation processes. Pore systems in Dingbian were dominated by residual intergranular pores (58–62% of total porosity) and secondary dissolution pores. In contrast, Wuqi reservoirs demonstrated superior pore connectivity through well-developed intergranular pores (65–72%), grain boundary pores, and microfracture networks. Pore throat characterization revealed distinct architectural patterns: Wuqi exhibited broad bimodal/multimodal distributions (0.1–50 μm) with 35–40% macro-throat (>10 μm) contribution to flow capacity, while Dingbian showed narrow unimodal distributions (1–10 μm) with <15% macro-throat participation. These microstructural divergences fundamentally governed contrasting production behaviors. Wuqi wells achieved higher initial flow rates (15–20 m3/d) with 60–70% water cut, yet maintained stable production through effective displacement systems enabled by dominant macropores. Conversely, Dingbian wells produced lower yields (5–8 m3/d) with 75–85% water cut, experiencing rapid 30–40% initial declines that transitioned to prolonged low-rate production phases. This petrophysical framework provides critical insights for optimized development strategies in heterogeneous tight sandstone reservoirs, particularly regarding water management and enhanced oil recovery potential. Full article
(This article belongs to the Special Issue Advanced Technology in Unconventional Resource Development)
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20 pages, 4837 KiB  
Article
Nano-Grafted Polymer Suspension Stabilizers for Oil Well Cement: Polymerization Innovation Dominated by Acrylamide and Breakthroughs in High-Temperature Applications
by Lifang Song, Chengwen Wang, Jingping Liu and Yang Li
Processes 2025, 13(2), 376; https://doi.org/10.3390/pr13020376 - 30 Jan 2025
Viewed by 722
Abstract
A high-temperature resistant suspension stabilizer, SIAM-1, for high-density cement slurry used in deep/ultra-deep well cementing has been successfully developed. This suspension stabilizer is based on the temperature-resistant monomers 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and N,N-dimethylacrylamide (NNDMA). Meanwhile, two functional monomers, long-hydrophobic-side-chain [...] Read more.
A high-temperature resistant suspension stabilizer, SIAM-1, for high-density cement slurry used in deep/ultra-deep well cementing has been successfully developed. This suspension stabilizer is based on the temperature-resistant monomers 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and N,N-dimethylacrylamide (NNDMA). Meanwhile, two functional monomers, long-hydrophobic-side-chain temperature-sensitive monomers and temperature-resistant monomer-modified nano-SiO2 monomers, were introduced. To enhance the participation of two functional monomers in the polymerization process, a method combining a small amount of acrylamide (AM) and emulsion polymerization was employed, leading to the successful synthesis of SIAM-1 with a high content of functional monomers. The study also explores the effects of polymerization method and AM on the conformational characteristics of the resulting polymers. The results confirm that the polymer structure aligns with the designed configuration, and SIAM-1 demonstrates excellent high-temperature resistance, with a tolerance of up to 210 °C. The optimal dosage of AM was found to be 4% of the total monomer mass. SIAM-1 exhibits excellent high-temperature rheological properties, maintaining a viscosity as high as 128 mP·s at 210 °C. Moreover, it effectively improves the suspension stability of the cement slurry at 210 °C. The density differences in the conventional-density and high-density cement slurries are 0.006 g∙cm−3 and 0.039 g∙cm−3, respectively. This research is beneficial for increasing the viscosity of the cement slurry at high temperatures, effectively preventing the settlement of solid-phase particles under high-temperature and high-pressure well conditions. Consequently, it enhances the cementing effect of deep/ultra-deep wells and reduces cementing-related risks. Full article
(This article belongs to the Special Issue Advanced Technology in Unconventional Resource Development)
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16 pages, 2661 KiB  
Article
Pressure Transient Analysis for Fractured Shale Gas Wells Using Trilinear Flow Model
by Li Liu, Liang Xue and Jiangxia Han
Processes 2024, 12(12), 2652; https://doi.org/10.3390/pr12122652 - 25 Nov 2024
Viewed by 832
Abstract
Shale gas, a low-permeability, unconventional resource, requires horizontal drilling and multi-stage fracturing for commercial production. This study develops a trilinear flow model for fractured horizontal wells in shale gas formations, incorporating key mechanisms such as adsorption, desorption, diffusion, wellbore storage, and skin effects. [...] Read more.
Shale gas, a low-permeability, unconventional resource, requires horizontal drilling and multi-stage fracturing for commercial production. This study develops a trilinear flow model for fractured horizontal wells in shale gas formations, incorporating key mechanisms such as adsorption, desorption, diffusion, wellbore storage, and skin effects. The model delineates seven distinct flow regimes, providing insights into gas migration processes and the factors controlling production. Sensitivity analyses reveal that desorption plays a critical role under low-pressure and low-production conditions, significantly enhancing gas transfer rates from the matrix to the fracture network and contributing to overall production. Monte Carlo simulations further highlight the variability in pressure responses under different input conditions, offering a comprehensive understanding of the model’s behavior in complex reservoir environments. These findings advance the characterization of shale gas flow dynamics and inform the optimization of production strategies. Full article
(This article belongs to the Special Issue Advanced Technology in Unconventional Resource Development)
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