Experimental characterization of CO2-oil slug flows near the supercritical state

This work presents an experimental characterization of CO₂-oil two-phase flows at pressures and temperatures near the critical conditions of CO₂. A high-pressure test bench with a 30 m long, one-inch pipe was developed to investigate flow conditions relevant to carbon capture, utilization, and storage applications and to Brazilian Pre-salt oil production. Dense CO₂ was injected into a light oil stream, and the resulting flow was observed through optical windows rated up to 80 bar. High-speed imaging and a Shadow Sizer system were used to identify long bubbles and to obtain distributions of bubble velocity, liquid-slug length, and bubble length. Single-phase oil measurements were also performed to characterize the friction factor of the test section. For the conditions reported here, the CO₂ density was approximately 200 kg m⁻³, producing a much smaller oil-to-gas density ratio than in conventional air-oil flows. The results show how this reduced density ratio affects the morphology and dynamics of slug flows and provide experimental data for model development and validation of high-pressure CO₂-oil flows.