Improvement of Environmental Monitoring Technology on the basis of Carbon Mass Balance during CO2-enhanced Oil Recovery and Storage☆

Abstract This study reviewed the emission inventory of carbon injection, production, storage, and emission. Results indicated that only approximately 95% of injected CO 2 can be measured. Approximately 92% to 95% of carbon was stored, 0.01% was leaked from soil, and the residual 5% may have come from leak paths or may have leaked from near-surface sources, such as underground water, through biological metabolism. To develop a carbon mass balance model for CO 2 enhanced oil recovery projects, the emission part from soil and underground water, as well as the fixation by vegetation, should be carefully measured. The residual 5% that remains unmeasured should be proven, i.e., whether such amount is derived along leak paths or is emitted from near-surface sources. Findings could highlight the fate of carbon, provide some suggestions to guide the selection of environmental monitoring technology, and aid in establishing a common methodology to identify leak risks for carbon storage projects.