With the rapid depletion of conventional energy production means such as coal and oil, more attention is paid to other sources of energy production such as natural gas, geothermal energy, and other renewable energy means, for example solar. On the other hand, the high carbon emission associated with oil and coal raises the importance of searching for new green energy technologies. Natural gas, such as coal seam gas is thus becoming a popular topic in the energy field. However, this involves a lot of limitations, mainly due to the lack of knowledge relating to the subject, the highly complex subsurface environment in coal seam gas reservoirs, and available ultra-low permeability.

In recent years, an appreciable amount of research is being conducted around the world to identify the complex multiphase system and fluid flow behavior in coal seam gas reservoirs, productivity enhancement techniques such as horizontal well drilling, hydraulic fracturing and in-situ leaching, and environmental and legal issues and costs associated with the various coal seam gas production techniques.

This Special Issue aims to collate original research and review articles that make a significant contribution to the coal seam gas extraction field. We seek to receive comprehensive reviews, micro to macro scale experimental evaluations and field studies, and analytical and numerical techniques related to coal seam gas extraction.

Potential topics include but are not limited to the following:

• Basic coal seam gas extraction technics, such as dewatering and their limitations
• Reservoir stimulation techniques, such as hydro fracking and gas-based fracturing
• Fracture network improving technics, such as chemical leaching, CO2 phase transition causing volume change, and thermal energy release.
• Image processing techniques to evaluate the water/gas flow behavior in rock matrix and fractures
• Potential hazards during coal seam gas extraction, such as seismic events, outbursts, ground water aquifer pollution
• Coupled hydro-thermo-mechanical process in coal seam gas reservoirs
• Changing of the multiphase flow behavior in coal seam gas reservoirs by reservoir stimulation techniques
• Water production during gas extraction and related issues
• Cost models and legal issues in coal seam gas extraction