Pressure, Pores, and CO2: The Formula for Better EOR

Lab experiments reveal how injection pressure and permeability steer CO2 EOR performance in US light oil reservoirs

13 Mar 2026

A new laboratory study is offering oil producers a clearer blueprint for designing CO2 injection programs in mature light oil fields. The research shows that recovery success hinges on two tightly linked variables: how hard CO2 is injected and the type of rock it moves through.

Published in January 2026 in the journal Gases, the study by Khaled Enab used core flooding experiments to examine how injection pressure and reservoir permeability interact. Two rock cores with different permeabilities were subjected to five injection pressures spanning immiscible, near-miscible, and fully miscible conditions. The result is one of the most structured experimental data sets yet produced for light oil CO2 enhanced oil recovery.

The findings reinforce a principle long discussed in theory but rarely mapped so clearly in controlled experiments. Higher injection pressure consistently improved recovery, with the most dramatic gains appearing once CO2 reached miscible conditions with the crude oil.

At that point, the gas behaves less like a simple pushing force and more like a solvent inside the reservoir. It dissolves into the oil, strips lighter hydrocarbons from rock surfaces, and reduces viscosity so the oil flows more freely toward production wells. When pressure falls out of the miscible range, the system loses much of that efficiency and residual oil saturation can rise by more than 20%.

What makes the study particularly useful for field operators is its focus on permeability. Rock with different pore structures alters how CO2 behaves underground, influencing the transition between gaseous, liquid, and supercritical states. Two reservoirs operating at the same injection pressure can therefore deliver very different recovery results if their pore networks differ.

For operators across Texas, Wyoming, Oklahoma, and Mississippi, where CO2 EOR already contributes more than 300,000 barrels per day, that insight adds practical precision. It suggests that flood design must account for rock characterization early rather than treating pressure targets as universal.

The work also highlights a strategic balancing act. Higher pressures that maximize oil recovery may reduce the amount of CO2 stored underground, an important factor for projects pursuing federal 45Q carbon storage incentives. As operators look to extend the life of aging fields, understanding that trade-off could shape the next generation of CO2 flood design.