Regional-Scale Greenhouse Gas Utilization Strategies for Enhanced Shale Oil Recovery and Carbon Management

Recent advances in shale oil development have largely outpaced efforts to manage associated greenhouse gas (GHG) emissions that pose significant environmental risks. In this work, we explore opportunities to leverage synergies between oil recovery and emission reduction targets through a regional case study in the Eagle Ford shale, where natural gas co-produced with oil (i.e., casinghead gas) is still frequently flared at the wellhead rather than sold due to a lack of pipeline infrastructure. We demonstrate that reinjecting casinghead gas for enhanced oil recovery (EOR) would be a profitable and environmentally favorable alternative to flaring, particularly considering the extent of oil that remains trapped in shales following primary recovery. On the basis of our projections of oil and casinghead gas production through 2025, this approach could prevent a cumulative 370 Bcf of flared gas (or abated emissions of 22 Mt CO2 eq) while recovering an additional 42.5 MMbbl of oil. Supplementing casinghead gas with anthropogenic CO2 emissions from natural gas processing facilities in the Haynesville shale could produce another 46.1 MMbbl of oil while sequestering 19.8 Mt CO2. We discuss the operational costs of this strategy, which could be competitive with traditional CO2-EOR (particularly in a carbon-constrained economy), but motivating industry adoption over cheaper conventional EOR approaches will require policy intervention and market assurances to mitigate long-term risks.