Properties and phenomena relevant to CH₄‐CO₂ replacement in hydrate‐bearing sediments

<jats:p>The injection of carbon dioxide, CO<jats:sub>2</jats:sub>, into methane hydrate‐bearing sediments causes the release of methane, CH<jats:sub>4</jats:sub>, and the formation of carbon dioxide hydrate, even if global pressure‐temperature conditions remain within the CH<jats:sub>4</jats:sub> hydrate stability field. This phenomenon, known as CH<jats:sub>4</jats:sub>‐CO<jats:sub>2</jats:sub> exchange or CH<jats:sub>4</jats:sub>‐CO<jats:sub>2</jats:sub> replacement, creates a unique opportunity to recover an energy resource, methane, while entrapping a greenhouse gas, carbon dioxide. Multiple coexisting processes are involved during CH<jats:sub>4</jats:sub>‐CO<jats:sub>2</jats:sub> replacement, including heat liberation, mass transport, volume change, and gas production among others. Therefore, the comprehensive analysis of CH<jats:sub>4</jats:sub>‐CO<jats:sub>2</jats:sub> related phenomena involves physico‐chemical parameters such as diffusivities, mutual solubilities, thermal properties, and pressure‐ and temperature‐dependent phase conditions. We combine new experimental results with published studies to generate a data set we use to evaluate reaction rates, to analyze underlying phenomena, to explore the pressure‐temperature region for optimal exchange, and to anticipate potential geomechanical implications for CH<jats:sub>4</jats:sub>‐CO<jats:sub>2</jats:sub> replacement in hydrate‐bearing sediments.</jats:p>