Water Balance Changes in Regional Aquifer System Due to Coal Seam Gas Development

Dear Colleagues,

The exploitation of Coal Seam Gas (CSG), a critical unconventional energy resource, inevitably disturbs the natural equilibrium of regional groundwater systems. A primary concern is the alteration of the water balance within connected aquifer systems, stemming from intensive dewatering practices used to depressurize coal seams for gas desorption. Studies show that produced water originates not only from the target coal seams but also, significantly, from adjacent aquifers in the roof and floor strata, especially when hydraulic fracturing creates pathways. At a micro-scale, molecular simulation studies are clarifying gas–water interactions and occurrence states within deep coal nanopores, providing a theoretical basis for understanding water mobility and invasion potential under different reservoir pressures.

Despite some progress having been made, significant knowledge gaps and technical challenges remain. Accurately predicting and managing high water production is difficult due to complex geological controls. A critical, unresolved issue is the long-term impact of large-scale water extraction and reinjection on regional aquifer water levels, quality, and the recovery potential of these systems post development. Moreover, novel development mechanisms, such as the gas–water "imbibition-displacement" effect observed in deep coal seams following massive hydraulic fracturing, challenge traditional models and introduce new variables into the water balance equation.

Meanwhile, these challenges are closely linked to the water resource issues encountered in conventional coal mining. However, coal seam gas development may differ from conventional mining in terms of impact mechanisms and scale. Currently, systematic comparative and integrated research on the hydrogeological impacts of both practices remains insufficient. Incorporating insights gained from conventional coal mining into the water management framework for coal seam gas development could contribute to building more comprehensive prediction models and control strategies.

We invite industry experts and researchers to contribute to this vital discussion. This collective effort is essential for developing sustainable CSG practices that safeguard precious water resources.

All manuscripts related to the proposed topic are welcome, with research areas including, without being limited to, the following themes:

• Occurrence Relationship and Co-production Mechanism of Coal Seam Gas and Coal Measures Groundwater;
• Quantifying Groundwater Depletion and Aquifer Drawdown from CSG Dewatering;
• Inter-aquifer Connectivity and Cross-formational Water Flow Induced by CSG Operations;
• Impacts of Hydraulic Fracturing on Aquifer Water Budget and Flow Paths;
• Source Identification and Tracing of CSG-Produced Water and Coal Mine Water;
• Long-term Aquifer Recovery and Water Level Rebound Post CSG and Coal Development;
• Integration of Numerical Modeling and Field Monitoring for Water Balance Prediction in CSG and Coal Zones;
• Water Quality Evolution and Geochemical Alterations in Aquifers Adjacent to CSG and Coal Zones;
• Sustainable Produced Water Management Strategies and Aquifer Protection during Coal and Gas Co-mining;
• Mechanisms and Prevention Strategies of Water Hazards in Coal Mining Areas.

Dr. Chen Guo
Dr. Reza Taherdangkoo
Dr. Zheng Zhang
Guest Editors

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 250 words) can be sent to the Editorial Office for assessment.

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. Water is an international peer-reviewed open access semimonthly 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 2600 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.

• coal seam gas (CSG) development
• regional aquifer system
• groundwater balance
• inter-aquifer connectivity
• hydrochemistry evolution
• numerical groundwater modeling
• environmental impact assessment