Improving CO2 Foam for EOR Applications Using Polyelectrolyte Complex Nanoparticles Tolerant of High Salinity Produced Water

摘要

Although surfactant generated CO2 foam improves the mobility control for CO2 flooding, it suffers from instability in the presence of crude oil and in high salinity environments. The objective of this work is to improve the stability of the interface by lowering surfactant drainage and improving the stability of lamellae in high salinity produced water using polyelectrolyte complex nanoparticles and generate a more stable foam front in the presence of crude oil. This results in improving the recovery efficiency of foam floods. In this project, an optimized system of polyelectrolyte complex nanoparticles was used to improve scCO2 foams prepared in high salinity produced water. The effect of nanoparticles on the interfacial properties of the foam was studied. Thereafter, a set of core flooding experiments with and without the crude oil in the system was conducted to measure the apparent viscosity and the incremental oil recovery due to addition of polyelectrolyte and polyelectrolyte complex nanoparticles to the surfactant generated CO2 foam in high salinity produced water. Studying the interfacial properties of different foam systems shows that addition of polyelectrolytes and polyelectrolyte complex nanoparticles to the surfactant generated CO2 foam improves the elasticity of the interface. Furthermore, adding polyelectrolytes and polyelectrolyte complex nanoparticles to the surfactant generated CO2 foam, improves the efficiency of the oil recovery by improving the apparent viscosity and making the foam more stable in the presence of crude oil. Polyelectrolyte complex nanoparticles produced incremental oil when the surfactant foam system reached its residual oil and produced no more oil. Generating a very stable system of the foam by adding polyelectrolyte complex nanoparticles to the surfactant generated CO2 foam prepared in high salinity produced water, results in a longer lasting foam and increase the incremental oil recovery up to 10%. The sea water salinity is applicable for all the locations with access to the sea water as well as locations with produced water salinities close to sea water. The higher salinity system covers a wide range of the reservoirs in the United States and worldwide with access to produced water.