| Summary: | A gas condensate reservoir in Northern Croatia was used as an example of a CO<sub>2</sub> injection site during natural gas production to test whether the entire process is carbon-negative. To confirm this hypothesis, all three elements of the CO<sub>2</sub> life cycle were included: (1) CO<sub>2</sub> emitted by combustion of the produced gas from the start of production from the respective field, (2) CO<sub>2</sub> that is separated at natural gas processing plant, i.e., the CO<sub>2</sub> that was present in the original reservoir gas composition, and (3) the injected CO<sub>2</sub> volumes. The selected reservoir is typical of gas-condensate reservoirs in Northern Croatia (and more generally in Drava Basin), as it contains about 50% CO<sub>2</sub> (mole). Reservoir simulations of history-matched model showed base case (production without injection) and several cases of CO<sub>2</sub> enhanced gas recovery, but with a focus on CO<sub>2</sub> storage rather than maximizing hydrocarbon gas production achieved by converting a production well to a CO<sub>2</sub> injection well. General findings are that even in gas reservoirs with such extreme initial CO<sub>2</sub> content, gas production with CO<sub>2</sub> injection can be carbon-negative. In almost all simulated CO<sub>2</sub> injection scenarios, the process is carbon-negative from the time of CO<sub>2</sub> injection, and in scenarios where CO<sub>2</sub> injection begins earlier, it is carbon-negative from the start of gas production, which opens up the possibility of cost-effective storage of CO<sub>2</sub> while producing natural gas with net negative CO<sub>2</sub> emissions.
|
|---|
