LOW-SALINITY WATER-FLOODING

1. Whether ALL of the four different following mechanisms remain to behave ‘similar’ both @ laboratory-scale as well as at field-scale?

(a) The presence of lower-salinity water causing the electrical double layer between the clay platelets present in the reservoir to expand and release fines, which act as a surfactant, and alter the permeability of the reservoir;

(b) Due to the increase in pH during a low-salinity injection, the interfacial tension getting reduced, and eventually, leading to a wettability alteration, where, the carboxylic compounds in the oil is assumed to be desorbed from the clay as a result of the pH increase;

(c) Using multicomponent ionic exchange (MIE), where, divalent cations residing in the formation water attract oil to the clay by forming a bridge across the thin film of water separating the oil and the clay, and thereby, binding the negatively charged carboxylate ions on the oil surface to the negatively charged exchange sites on the clay surface;

(d) As the concentration of divalent ions in the injected water gets decreased, the ions attracting the oil to the clay migrate into the bulk liquid, and are replaced by monovalent ions, allowing the release of oil, where, the thin film of water between the oil and clay keeps expanding in the low-salinity regime, due to electric double-layer expansion, reducing the attraction of the oil to the clay surface, and thus assisting the release of oil.

2. Could we predict the thickness of the thin layer of water between the clay and oil (resulting from the balancing of the capillary pressure and electro-osmotic pressure associated with DVLO theory of colloidal stability, where, the disjoining pressure is assumed to be taken to be the same as between two flat plates), if the film thickness below the moving oil-droplet remains to depend on the velocity at which the oil-droplet moves (considering it as a dynamic model that considers Bretherton effects, as against considering it using conventional static model using the assumption of static meniscus)?