CO2 can be used to recover more oil from shale formations and store carbon underground. A method called huff-n-puff was used to inject CO2 into the shale, increasing oil recovery by 10%. During this process, 27%–70% of the injected CO2 was trapped, with most of it dissolving in the shale oil. Economic analysis showed that the feasibility of CO2 injection depends on oil prices, and higher carbon taxes favor scenarios with more CO2 storage. This study supports the idea of storing CO2 in shale reservoirs and can help in forming carbon tax policies.