About this Research Topic
Natural gas is the cleanest fossil fuel and has been recognized as one of the most substantial energy resources due to its abundance and environmental reliability. The reserves of unconventional natural gas (e.g. shale gas, coalbed methane, tight gas, and natural gas hydrate) are approximately 2 times larger than the reserves of conventional natural gas. Over the past two decades, the significant demand growth on natural gas has motivated the production of unconventional natural gas. In recent years, CO2 injection (e.g. gaseous, liquid, or supercritical) has been considered as the most promising method for the recovery of unconventional natural gas in terms of technical and profitability aspects as it can not only enhance gas production but also sequester CO2 efficiently in underground reservoirs. Thus, the CO2 enhanced technology for unconventional natural gas production will make a significant contribution to CO2 mitigation and energy recovery. Moreover, further studies of this technology will maximize the potentials of unconventional natural gas production and improve the capacity of CO2 capture and sequestration in natural gas reservoirs.
Due to the advancement of CO2 enhanced recovery of natural gas in the past 10 years, this promising technology is undergoing the development from laboratory experiments and simulations to some field pilots. On the other hand, the efficiency and cost at present cannot meet the requirement of commercialization. This is because several problems still exist, including the diversity of natural gas reservoirs, the unknown thermophysical properties of gas reservoirs during CO2 injection, the unknown mechanisms of heat and mass transfer and the fluid transport in gas reservoirs, the CO2 promotion mechanism as well as the CO2 sequestration mechanism. In addition, the complexity of unconventional natural gas reservoirs is not well understood, especially the reservoirs with ultralow permeability or the reservoirs existing in ocean floors, and the superior models that can be employed for economic evaluation are not available. Therefore, this Research Topic presents both summaries on and the most recent developments in the studies of CO2 enhanced recovery of various unconventional natural gases including shale gas, coalbed methane, natural gas hydrate, etc., with a focus on the diversity and complexity of natural gas reservoirs, especially the reservoirs with ultralow permeability. The aim is to provide guidance for the development of CO2 enhanced technologies that will enable cost-effective natural gas recovery and CO2 sequestration in natural gas reservoirs.
The current Research Topic aims to cover promising and novel technology trends in CO2 enhanced recovery of unconventional natural gas. Article types including Original Research, Reviews, Mini Reviews, and Perspectives will be welcome. Areas to be covered in this Research Topic may include, but are not limited to:
• Characterization of unconventional natural gas reservoirs under CO2 effect
• Fundamentals of CO2 enhanced natural gas recovery
• Novel research of CO2 storage in natural gas reservoirs
• Economic evaluation of natural gas production and CO2 storage in gas reservoirs
• Novel research of CO2 capture and separation from natural gas
Keywords: CO2 capture and sequestration, natural gas, shale gas, coal bed methane, gas hydrates
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