Surfactant Foam assisted CO2 EOR, though getting traction for its environomic mobility control potential, faces numerous challenges for deployment in HPHTHS heterogeneous carbonate reservoirs. Amongst the major challenges, the first is the lack of a surfactant formulation compatible with our carbonate reservoirs and the second is the absence of a foam and CO2 front monitoring tool either at laboratory or field scale.

In this study, a novel monitoring technique has been developed to track quality of the foam while core-flooding. This is essential to capture the onset formation, development rate and break-through of the said foam across varying length of core-plugs. This has been previously conducted in lab-scale by virtue of pressure response with or without expensive imaging methods. This tool complements the conventional method of studying pressure response with resistance measurements across the core allowing tracking of the foam generation and propagation. Various preconditioning smart brines (SB) were alternatively injected with the non-ionic surfactant APG, co-injected with gas, to generate foam in-situ in carbonate reservoir samples. In addition, we briefly discuss a new idea involving resistivity and pressure measurements for the optimization of foam (and CO2 foam) injection into porous media

The foam generation, stability and breakthrough were studied as a function of salinity, ion composition and injected pore volumes of the various brines and surfactant. Core-plugs of 2 different rock types were flooded with 4 variations of smart brines at a constant flow rate. The tested formulations were ramped up from 2 to 8 pore volumes. The response of the ΔP/PV integrated with the Δρ/PV curves were analysed to detect foam generation and breakthrough. This allowed an immediate characterization of the foam performance providing capability of tracking the foam formation/dissipation across the length of the core-plugs, essential for compatible successful foam formulation.

This novel method allowed for instantaneous resistance observations in lab-scale along with the pressure response. The performance of the monitoring technique provided a new dimension in understanding foam flooding. This was integrated to provide comprehensive analysis of the formulated foam. Our innovative method provides the capability of quicker screening to successfully generate foam in-situ in high salinity, hardness and heterogenic environment.

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