To mitigate the challenge of climate change caused by carbon dioxide (CO₂) and other greenhouse gases produced due to human-activities, two aspects of effort are being made globally. The way of capturing and storing the greenhouse-gas released from combustion of the first one is through fossil fuels, to reduce the amount of the gas emission into the atmosphere or the marine accumulation of the gas. The second one is to develop alternative, renewable energy resources that are of zero or much less greenhouse-gas emission to reduce or to replace the use of fossil fuels.

Sequestration of the greenhouse-gas in geological formations and utilisation of CO₂ to enhance extraction of geothermal energy from the subsurface are, amid many other techniques, two typical practices towards the goal of controlling or slowing the trend of climate change whose destructive impacts to the earth have already been observed. Over the past two decades, there have been a number of pioneering field-trials in the world for geological storage of CO₂ and other greenhouse gases. Additionally, there have been many successful applications for enhancing production of the geothermal energy.

Geological sequestration of the greenhouse-gas and extraction of the geoenergy from the subsurface are two opposite flow processes. Nevertheless, they share a lot in common; both disturb the (dynamic) equilibria of the natural environment in the subsurface and may result in complex physical, chemical, mechanical, and thermal changes to the local geological circumstance. These changes would, in turn, affect the relevant operational efficiency and could also give rise to additional, unexpected environmental safety and security issues. Therefore, it is crucial to have in-depth understanding to what changes may be introduced there, and how the fluid flow behaves under these changes.

We solicit high-quality, original research articles as well as review papers focused on geological sequestration of CO₂/other greenhouse gases and the utilisation of CO₂ to extract geoenergy from the subsurface. The work can be based on theoretical and numerical analyses, or the laboratory tests. Case or field-oriented studies, which bring in new insights with practical observations, are also welcome.

Potential topics include but are not limited to the following:

• Nonisothermal flow behaviour of stored CO₂ and other greenhouse gases in geological formations
• The use of CO₂ for enhancing recovery of subsurface energies such as oil, gas, and geothermal resources
• Mechanical failure of storage or sealing formations due to injected CO₂ and other greenhouse gases
• Hydrothermal-mechanical coupling processes associated with CO₂ transport in sedimentary rocks
• Risk and safety assessment for stored CO₂ and other greenhouse gases in geological formations and the potential impacts on geological environments
• Chemical reactions induced by injected CO₂ and other greenhouse gases with sedimentary rocks
• Theory, numerical simulation, and operation techniques in relation to geothermal energy exploration and development
• Application of hydraulic fracturing to geothermal energy utilisation and its impact on geological environment
• Direct imaging of CO₂ distribution in cores
• Performance standards and site-specific assessments of geochemical and hydrological conditions