Processes

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Special Issue Editors

Dr. Xiaoguang Wu

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Guest Editor

College of Carbon Neutral Energy, China University of Petroleum (Beijing), Beijing 102249, China
Interests: hydraulic fracturing; hydra-jet drilling and well completion; geothermal stimulation and development

Dr. Xianwei Dai

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Guest Editor

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China
Interests: PDC bit; rock breaking; hot dry rock; numerical simulation
Special Issues, Collections and Topics in MDPI journals

Dr. Xu Zhang

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Guest Editor Assistant

School of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102249, China
Interests: geothermal energy; hydraulic fracturing; numerical simulation

Special Issue Information

Dear Colleagues,

Unconventional reservoirs, with their vast reserves and extensive distribution, have become key to future energy development. Hydraulic fracturing is a stimulation technique utilized in low-permeability unconventional reservoirs such as tight sandstone, shale, certain coal beds, and geothermal reservoirs. However, there is a pressing need for intensified efforts to advance innovative hydraulic fracturing technologies. These advancements should focus on improving efficiency, ensuring cost-effectiveness, and mitigating environmental impact.

This Special Issue, titled “Innovations in Hydraulic Fracturing Technology for Unconventional Reservoirs”, aims to cover the recent advances in hydraulic fracturing technology in unconventional reservoirs. Topics of interest include, but are not limited to, the following areas:

New theories, models, and numerical simulation methods for hydraulic fracturing;
Innovative fracturing method and technology in low-permeability oil and gas reservoir (tight oil and gas, shale oil and gas, etc.), coalbed methane, natural gas hydrate, geothermal, etc.;
Cross-layer fracturing in laminated reservoirs;
Carbonate reservoir acid fracturing;
Ultra-deep high-temperature high-pressure reservoir fracturing;
CO₂ fracturing and CCUS technology;
Novel fracturing materials (fracturing fuild, proppant, etc.) and tools;
Non-aqueous fracturing technology;
Hydraulic fracturing assied by artificial intelligence, internet of things, and big data;
Monitoring and evaluation of hydraulic fracturing (fiber-optic cables, etc.);
Envoiromental risks and seism reduction.

Dr. Xiaoguang Wu
Dr. Xianwei Dai
Guest Editors

Dr. Xu Zhang
Guest Editor Assistant

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

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

unconventional reservoir
hydraulic fracturing
coalbed methane
natural gas hydrate
geothermal reservoir
ultra-deep reservoir
artificial intelligence
CCUS
fracturing monitoring techniques
novel fracturing materials

Published Papers (2 papers)

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Research

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22 pages, 8635 KiB

Open AccessArticle

Study on the Interaction Propagation Mechanism of Inter-Cluster Fractures under Different Fracturing Sequences

by Xiaojun Cai, Weixuan Zhao, Tianbao Hu, Xinwei Du, Haiyang Wang and Xiong Liu

Processes 2024, 12(5), 971; https://doi.org/10.3390/pr12050971 - 10 May 2024

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Abstract

Horizontal-well multi-cluster fracturing is one of the most important techniques for increasing the recovery rate in unconventional oil and gas reservoir development. However, under the influence of complex induced stress fields, the mechanism of interaction and propagation of fractures within each segment remains unclear. In this study, based on rock fracture criteria, combined with the boundary element displacement discontinuity method, a two-dimensional numerical simulation model of hydraulic fracturing crack propagation in a planar plane was established. Using this model, the interaction and propagation process of inter-cluster fractures under different fracturing sequences within horizontal well segments and the mechanism of induced stress field effects were analyzed. The influence mechanism of cluster spacing, fracture design length, and fracture internal pressure on the propagation morphology of inter-cluster fractures was also investigated. The research results indicate that, when using the alternating fracturing method, it is advisable to appropriately increase the cluster spacing to weaken the inhibitory effect of induced stress around the fractures created by prior fracturing on subsequent fracturing. Compared to the alternating fracturing method, the propagation morphology of fractures under the symmetrical fracturing method is more complex. At smaller cluster spacing, fractures created by prior fracturing are more susceptible to being captured by fractures from subsequent fracturing. The findings of this study provide reliable theoretical support for the optimization design of fracturing sequences and fracturing processes in horizontal well segments. Full article

(This article belongs to the Special Issue Innovations in Hydraulic Fracturing Technology for Unconventional Reservoirs)

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Review

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22 pages, 6498 KiB

Open AccessReview

Review of Shale Oil and Gas Refracturing: Techniques and Field Applications

by Liru Xu, Dajiang Wang, Lizhi Liu, Chen Wang, Haiyan Zhu and Xuanhe Tang

Processes 2024, 12(5), 965; https://doi.org/10.3390/pr12050965 - 9 May 2024

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Abstract

Shale oil and gas wells usually experience a rapid decline in production due to their extremely low permeability and strong heterogeneity. As a crucial technique to harness potential and elevate extraction rates in aged wells (formations), refracturing is increasingly employed within oil and gas reservoirs globally. At present, the selection processes for refracturing, both of wells and layers, are somewhat subjective and necessitate considerable field data. However, the status of fracturing technology is difficult to control precisely, and the difference in construction effects is large. In this paper, well selection, formation selection, and the fracturing technology of shale oil and gas refracturing are deeply analyzed, and the technological status and main technical direction of refracturing technology at home and abroad are analyzed and summarized. The applicability, application potential, and main technical challenges of existing technology for different wells are discussed, combined with the field production dynamics. The results show that well and layer selection is the key to the successful application of refracturing technology, and the geological engineering parameters closely related to the remaining reservoir reserves and formation energy should be considered as the screening parameters. General temporary plugging refracturing technology has a low cost and a simple process, but it is difficult to accurately control the location of temporary plugging, and the construction effect is very different. Mechanical isolation refracturing technology permits the exact refurbishment of regions untouched by the initial fracturing. However, it is costly and complex in terms of construction. Consequently, cutting the costs of mechanical isolation refracturing technology stands as a pivotal research direction. Full article

(This article belongs to the Special Issue Innovations in Hydraulic Fracturing Technology for Unconventional Reservoirs)

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