Slugging process characteristics

Typical EOR surfactant-polymer flooding operations include a sequence of slugs (see Fig. 10.3) that are injected into an oil reservoir [109, 113, 114, 119]. The main idea is to wrap up a process to recover most of the oil still in place (at least much more than what waterflooding does) by preserving at the correct level the main characteristics and functions of the different slugs, particularly the surfactant one, as they pass through the reservoir from the injector to the producer wells. Some of the typical slugs and their main features are described below. 

In microfluidic devices, multiphase flows are created when two (or more) immiscible fluids come into contact. Depending on the interaction between the mterfacial and viscous forces, the resulting multiphase flow can take different forms, such as suspended droplets, slugs (droplets occupying the whole channel) or stratified flow (parallel) [141, 142]. In addition to the forces exerted between the two liquids, the channel geometry and physical characteristics also play an important role in the process [143]. In this respect, the use of hydrophobic channels is suitable for the formation of water-m-oil emulsions, whereas hydrophilic channels favor the creation of oil-m-water emulsions [144]. 

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