Microscopic scale interactions of water ions at crude oil/water interface and their impact on oil mobilization in advanced water flooding

These interesting results observed with calcium and magnesium ions at crude oil-water interface are expected to favorably impact oil mobilization in advanced water flooding processes. Such favorable interactions can quickly destabilize the interfacial film between oil and water (due to less viscous interfaces) to promote the coalescence between released oil droplets and enable faster oil mobilization. This coalescence process is also sequential and it would continue until the formation of small oil bank. The coalescence times measured between oil droplets confirmed the adverse impact of sulfate ions, to hinder the coalescence and delay oil mobilization, in consistent with interfacial shear rheology results. The new fundamental knowledge gained in this study would provide an important guidance on how to synergize water ion interactions at fluid-fluid interfaces with those at rock-fluids interfaces and optimize advanced water flooding processes in carbonate reservoirs.