Emulsion characterization under reservoir/ operational conditions

Abstract

Emulsions are complex systems, composed by two immiscible liquid phases in which one phase is dispersed into another by shear forces and/or turbulences. In oil production, water, oil and gas are coproduced and flow along the production lines from the well to the topside unities, being subjected to continuous changes in pressure and temperature.Along the lifting process, changes in pressure and temperature strongly affect the gas/liquid phase equilibrium and, as a consequence, the physical properties of all coproduced phases. Even though the viscosity and density are the parameters more straightly connected to PVT conditions (Ghaderi et al., 2014), a range of physicochemical processes may also occur in the bulk of both water and oil phases.In real production systems, several processes are dependent on the gas-liquid equilibrium, such as asphaltenes precipitation in the oil phase and salts precipitation in the water phase. Besides that, variations in viscosity and density of the oil phase, as a consequence of the gas-oil equilibrium, also impacts parameters of the emulsions such as mean size, size distribution, viscosity and rheological behavior of the emulsions. The possibility of asphaltene and/ or inorganic salt crystals as finely divided solids at specific conditions of P and T may make the system even more complex. In emulsions, fine solids are prone to adsorb at water/ oil interfaces and cause a series of changes of the interfacial properties and, consequently, on the viscosity, rheological behavior and emulsion stability by pickering (Sjoblom, 2007; Low et al., 2020). Thus, the intricate relationship among the phase composition, pressure and temperature turn the prediction of emulsion properties in reservoir conditions quite difficult from dead oil samples at ambient conditions.The studies will start with the development of a methodology to measure the emulsion properties of emulsions under P and T values representative of the production systems. The methodology will involve the procedure to prepare emulsions inside a PVT cell and the measurements of the emulsion properties, not yet well defined in the literature. It will be obtained among the P, T conditions and physical properties, such as viscosity and density, and if there are changes in viscosity and density trends in case of asphaltene and/ or salt precipitation. It will be also investigated if the pressure and temperature affect the mean size and size distribution of droplets. The tests will cover two distinct scenarios: heavy oil and light oil (pre-salt).