An Automated Sandpack as a New Intermediate Test for EOR Foam Formulation Design

摘要

Foams are now a well-accepted method for conformance control in a wide range of EOR gas floods, from produced gas re-injection in the North Sea to CO2 EOR applications in the US. To maximize the chances of success of a foam process, both the composition of the aqueous foaming solution (salinity, surfactants, polymers...) and the process parameters (foam gas fraction, injection flow rates,...) must be optimized. This is generally done by combining bulk foam experiments and heavy petrophysics application tests, which limits the number of experiments carried out for the process optimization. We present here a new experimental approach based on an automated porous media set-up with in-situ flow visualization. This sandpack design allows changing automatically the injection velocity and gas fraction and thus speeding-up an extensive mapping of performances of numerous formulations. This helps selecting the most adapted formulation. In addition to automation, the direct flow visualization through thick rectangular glass windows allows to characterize the transport of the colored aqueous and oil phases by a proper selection of dyes. The possibilities of in-situ velocities measurement thus brings new insight on foam flow in porous media with and without oil. Moreover, this tool, through the generated set of data, helps clarifying the relation between the bulk foam properties such as foamability, foam stability and the performances in porous media such as relative mobility reduction and conditions for efficient foam generation. Stability of bulk foam but also the ability for a formulation to create foam lamellae are evidenced as key parameters to control the apparent viscosity in porous media. Overall, this study presents both a new high-throughput tool as an intermediate test between bulk foam and petrophysics measurements, and a set of data generated with this sandpack which brings new insights on foam flows in EOR processes.